bims-auttor Biomed News
on Autophagy and mTOR
Issue of 2023‒11‒19
87 papers selected by
Viktor Korolchuk, Newcastle University
  1. Activation of Lysosomal Function Ameliorates Amyloid-β-Induced Tight Junction Disruption in the Retinal Pigment Epithelium.
  2. NCoR1: a key player regulating mycobacterium tuberculosis pathogenesis.
  3. Autophagy: A Silent Protagonist in Kidney Transplantation.
  4. Aerobic exercise attenuates autophagy-lysosomal flux deficits by ADRB2/β2-adrenergic receptor-mediated V-ATPase assembly factor VMA21 signaling in APP-PSEN1/PS1 mice.
  5. Ups and downs of lysosomal pH: conflicting roles of LAMP proteins?
  6. PDZD8 promotes autophagy at ER-Lysosome contact sites to regulate synaptogenesis.
  7. Autophagy gene expression in skeletal muscle of older individuals is associated with physical performance, muscle volume and mitochondrial function in the Study of Muscle, Mobility and Aging (SOMMA).
  8. Involvement of Lipophagy and Chaperone-Mediated Autophagy in the Pathogenesis of Non-Alcoholic Fatty Liver Disease by Regulation of Lipid Droplets.
  9. CELLULAR, A Cell Autophagy Imaging Dataset.
  10. Conversion of methylmercury into inorganic mercury via organomercurial lyase (MerB) activates autophagy and aggresome formation.
  11. Targeted suppression of mTORC2 reduces seizures across models of epilepsy.
  12. Engineering cannabidiol synergistic carbon monoxide nanocomplexes to enhance cancer therapy via excessive autophagy.
  13. Local membrane source gathering by p62 body drives autophagosome formation.
  14. Activation of moderate autophagy promotes survival of fat graft.
  15. A drug-like molecule engages nuclear hormone receptor DAF-12/FXR to regulate mitophagy and extend lifespan.
  16. SCD1 and monounsaturated lipids are required for autophagy and survival of adipocytes.
  17. Multi-modal proteomic characterization of lysosomal function and proteostasis in progranulin-deficient neurons.
  18. Drug discovery by targeting the protein-protein interactions involved in autophagy.
  19. Autophagy in Disease Onset and Progression.
  20. Kinesin family member 18B activates mTORC1 signaling via actin gamma 1 to promote the recurrence of human hepatocellular carcinoma.
  21. Role of mitophagy in ocular neurodegeneration.
  22. Autophagy regulates tumor growth and metastasis.
  23. New Insights into Plant Autophagy: Molecular Mechanisms and Roles in Development and Stress Responses.
  24. Integration of FUNDC1-associated mitochondrial protein import and mitochondrial quality control contributes to TDP-43 degradation.
  25. Autophagy machinery in glioblastoma: The prospect of cell death crosstalk and drug resistance with bioinformatics analysis.
  26. Restraint Stress, Foot Shock and Corticosterone Differentially Alter Autophagy in the Rat Hippocampus, Basolateral Amygdala and Prefrontal Cortex.
  27. mTOR inhibition suppresses salinomycin-induced ferroptosis in breast cancer stem cells by ironing out mitochondrial dysfunctions.
  28. TOR Complex 1: Orchestrating Nutrient Signaling and Cell Cycle Progression.
  29. Role and molecular regulatory mechanisms of Hippo signaling pathway in Caenorhabditis elegans and mammalian cell models of Alzheimer's disease.
  30. Branched-Chain Amino Acid Accumulation Fuels the Senescence-Associated Secretory Phenotype.
  31. Knockout or inhibition of USP30 protects dopaminergic neurons in a Parkinson's disease mouse model.
  32. Targeting autophagy in Alzheimer's disease: Animal models and mechanisms.
  33. CTCF modulates adipocyte lipolysis via directly regulating the expression of Beclin 1 with the cooperation of PPARγ.
  34. Pycard deficiency inhibits microRNA maturation and prevents neointima formation by promoting chaperone-mediated autophagic degradation of AGO2/argonaute 2 in adipose tissue.
  35. Reprogramming tumor-associated macrophages to outcompete endovascular endothelial progenitor cells and suppress tumor neoangiogenesis.
  36. The Sonic hedgehog pathway inhibitor GDC0449 induces autophagic death in human Medulloblastoma Daoy cells.
  37. Macrophage autophagy deficiency-induced CEBPB accumulation alleviates atopic dermatitis via impairing M2 polarization.
  38. Collapse of late endosomal pH elicits a rapid Rab7 response via V-ATPase and RILP.
  39. Knockdown of Y-box binding protein 1 induces autophagy in early porcine embryos.
  40. CHOP upregulation and dysregulation of the mature form of the SNAT2 amino acid transporter in the placentas from small for gestational age newborns.
  41. APOL1-G2 accelerates nephrocyte cell death by inhibiting the autophagy pathway.
  42. Evaluation of hepatic AMP-activated protein kinase (AMPK), mechanistic target of rapamycin kinase complex 1 (mTORC1) and autophagy-lysosomal pathway in cows with mild or moderate fatty liver.
  43. RapaLink-1 outperforms rapamycin in alleviating allogeneic graft rejection by inhibiting the mTORC1-4E-BP1 pathway in mice.
  44. Intermittent Fasting Attenuates Metabolic-Dysfunction-Associated Steatohepatitis by Enhancing the Hepatic Autophagy-Lysosome Pathway.
  45. Autophagy activates EGR1 via MAPK/ERK to induce FGF2 in renal tubular cells for fibroblast activation and fibrosis during maladaptive kidney repair.
  46. Current Advances in the Regulatory Effects of Bioactive Compounds from Dietary Resources on Nonalcoholic Fatty Liver Disease: Role of Autophagy.
  47. Autophagy core protein BECN1 is vital for spermatogenesis and male fertility in mice.
  48. ATR promotes mTORC1 activation via de novo cholesterol synthesis in p16-low cancer cells.
  49. Active growth signaling promotes senescence and cancer cell sensitivity to CDK7 inhibition.
  50. The PtdIns3P phosphatase MtMP promotes symbiotic nitrogen fixation via mitophagy in Medicago truncatula.
  51. TFEB SUMOylation in macrophages accelerates atherosclerosis by promoting the formation of foam cells through inhibiting lysosomal activity.
  52. Activation of mitophagy improves cognitive dysfunction in diabetic mice with recurrent non-severe hypoglycemia.
  53. METTL3-mediated maturation of miR-192-5p targets ATG7 to prevent Schwann cell autophagy in peripheral nerve injury.
  54. Iron deficiency-induced ferritinophagy impairs skeletal muscle regeneration through RNF20-mediated H2Bub1 modification.
  55. PHB2 Alleviates Neurotoxicity of Prion Peptide PrP106-126 via PINK1/Parkin-Dependent Mitophagy.
  56. Efficient protocol for the differentiation of kidney podocytes from induced pluripotent stem cells, involving the inhibition of mTOR.
  57. Inhibition of excessive autophagy alleviates renal injury and inflammation in a rat model of immunoglobulin A nephropathy.
  58. Lipid structure matters in lysosomal storage disease.
  59. Targeting PKD2 aggravates ferritinophagy-mediated ferroptosis via promoting autophagosome-lysosome fusion and enhances efficacy of carboplatin in lung adenocarcinoma.
  60. FKBP5 activates mitophagy by ablating PPAR-γ to shape a benign remyelination environment.
  61. Docosahexaenoic acid (DHA) inhibits abdominal fat accumulation by promoting adipocyte apoptosis through PPARγ-LC3-BNIP3 pathway-mediated mitophagy.
  62. New tools can propel research in lysosomal storage diseases.
  63. Detoxified pneumolysin derivative ΔA146Ply inhibits triple- negative breast cancer metastasis mainly via mannose receptor-mediated autophagy inhibition.
  64. Knockdown of neuronal DAF-15/Raptor promotes healthy aging in C. elegans.
  65. Mitochondrial dysfunction in Parkinson's disease - a key disease hallmark with therapeutic potential.
  66. DDIT4 is essential for DINP-induced autophagy of ovarian granulosa cells.
  67. Transcription factor FOXM1 specifies chromatin DNA to extracellular vesicles.
  68. The Role of mRNA Quality Control in the Aging of Caenorhabditis elegans.
  69. Inhibition of Hedgehog signaling ameliorates foam cell formation by promoting autophagy in early atherosclerosis.
  70. Skeletal muscle TFEB signaling promotes central nervous system function and reduces neuroinflammation during aging and neurodegenerative disease.
  71. Targeting DGAT1 inhibits prostate cancer cells growth by inducing autophagy flux blockage via oxidative stress.
  72. Adjusted vascular contractility relies on integrity of progranulin pathway: Insights into mitochondrial function.
  73. ER-Specific Autophagy or ER-Phagy in Cardiac Myocytes Protects the Heart Against Doxorubicin-Induced Cardiotoxicity.
  74. CPT1A mediates chemoresistance in human hypopharyngeal squamous cell carcinoma via ATG16L1-dependent cellular autophagy.
  75. Unlocking the Secrets of Aging: Epigenetic Reader BRD4 as the Target to Combatting Aging-Related Diseases.
  76. Miriplatin-loaded liposome, as a novel mitophagy inducer, suppresses pancreatic cancer proliferation through blocking POLG and TFAM-mediated mtDNA replication.
  77. ZnO nanoparticles impair autophagic flux and cell viability through the TRIM16-NRF2-p62 pathway in inflammatory keratinocytes.
  78. Inhibition of autophagy initiation: A novel strategy for oral squamous cell carcinomas.
  79. TORC pathway intersects with a calcium sensor kinase network to regulate potassium sensing in Arabidopsis.
  80. Mitochondria-associated membrane collapse impairs TBK1-mediated proteostatic stress response in ALS.
  81. Hippocampal TMEM55B overexpression in the 5XFAD mouse model of Alzheimer's disease.
  82. Placental extract suppresses lipid droplet accumulation by autophagy during the differentiation of adipose-derived mesenchymal stromal/stem cells into mature adipocytes.
  83. Aloperine targets lysosomes to inhibit late autophagy and induces cell death through apoptosis and paraptosis in glioblastoma.
  84. The intensity-dependent effects of exercise and superimposing environmental heat stress on autophagy in peripheral blood mononuclear cells from older men.
  85. FAT1 inhibits AML autophagy and proliferation via downregulating ATG4B expression.
  86. Endoplasmic Reticulum Selective Autophagy Alleviates Anthracycline-Induced Cardiotoxicity.
  87. Melatonin-mediated mitophagy protects against long-term impairments after repeated neonatal sevoflurane exposures.
  1. Mol Cells. 2023 Nov 30. 46(11): 675-687
    Activation of Lysosomal Function Ameliorates Amyloid-β-Induced Tight Junction Disruption in the Retinal Pigment Epithelium.
    Dong Hyun Jo, Su Hyun Lee, Minsol Jeon, Chang Sik Cho, Da-Eun Kim, Hyunkyung Kim, Jeong Hun Kim.
      Accumulation of pathogenic amyloid-β disrupts the tight junction of retinal pigment epithelium (RPE), one of its senescence-like structural alterations. In the clearance of amyloid-β, the autophagy-lysosome pathway plays the crucial role. In this context, mammalian target of rapamycin (mTOR) inhibits the process of autophagy and lysosomal degradation, acting as a potential therapeutic target for age-associated disorders. However, efficacy of targeting mTOR to treat age-related macular degeneration remains largely elusive. Here, we validated the therapeutic efficacy of the mTOR inhibitors, Torin and PP242, in clearing amyloid-β by inducing the autophagy-lysosome pathway in a mouse model with pathogenic amyloid-β with tight junction disruption of RPE, which is evident in dry age-related macular degeneration. High concentration of amyloid-β oligomers induced autophagy-lysosome pathway impairment accompanied by the accumulation of p62 and decreased lysosomal activity in RPE cells. However, Torin and PP242 treatment restored the lysosomal activity via activation of LAMP2 and facilitated the clearance of amyloid-β in vitro and in vivo. Furthermore, clearance of amyloid-β by Torin and PP242 ameliorated the tight junction disruption of RPE in vivo. Overall, our findings suggest mTOR inhibition as a new therapeutic strategy for the restoration of tight junctions in age-related macular degeneration.
    Keywords:  LAMP2; PP242; Torin; age-related macular degeneration; amyloid-β; autophagy-lysosome pathway
    DOI:  https://doi.org/10.14348/molcells.2023.0056
  2. Autophagy. 2023 Nov 12. 1-2
    NCoR1: a key player regulating mycobacterium tuberculosis pathogenesis.
    Kaushik Sen, Viplov Kumar Biswas, Arup Ghosh, Subhasish Prusty, Sourya Prakash Nayak, Sreeparna Podder, Bhawna Gupta, Sunil Kumar Raghav.
      Mycobacterium tuberculosis (Mtb) employs a multifaceted arsenal to elude host defense mechanisms, including those associated with autophagy and lysosome function. Within the realm of host-pathogen interactions, NCOR1, a well-recognized transcriptional co-repressor, is known to associate with a multitude of protein complexes to effect the repression of a diverse spectrum of genes. However, its role in regulating macroautophagy/autophagy, lysosome biogenesis, and, by extension, Mtb pathogenesis remains unexplored. The depletion of NCOR1 assumes a pivotal role in the control of the AMPK-MTOR-TFEB signaling axis, thereby fine-tuning cellular ATP homeostasis. This finely orchestrated adjustment further alters the profile of proteins involved in autophagy and lysosomal biogenesis through its master regulator, TFEB, culminating in the increased Mtb survival within the host milieu. Furthermore, the treatment of NCOR1-depleted cells with either rapamycin, antimycin A, or metformin demonstrates a capacity to restore the TFEB activity and LC3-II levels, consequently restoring the capacity of host cells to clear Mtb. Additionally, exogenous NCOR1 expression rescues the AMPK-MTOR-TFEB signaling axis and essentially the autophagic induction machinery. Overall, these findings demonstrate a crucial role of NCOR1 in regulating Mtb pathogenesis within myeloid cells and sheds light toward its involvement in the development of novel host-directed therapies.
    Keywords:  AMPK; MTOR; NCOR1; TFEB; mycobacterium tuberculosis
    DOI:  https://doi.org/10.1080/15548627.2023.2277583
  3. Transplantation. 2023 Nov 13.
    Autophagy: A Silent Protagonist in Kidney Transplantation.
    Claudio Ponticelli, Francesco Reggiani, Gabriella Moroni.
      Autophagy is a lysosome-dependent regulated mechanism that recycles unnecessary cytoplasmic components. It is now known that autophagy dysfunction may have a pathogenic role in several human diseases and conditions, including kidney transplantation. Both defective and excessive autophagy may induce or aggravate several complications of kidney transplantation, such as ischemia-reperfusion injury, alloimmune response, and immunosuppressive treatment and side effects. Although it is still complicated to measure autophagy levels in clinical practice, more attention should be paid to the factors that may influence autophagy. In kidney transplantation, the association of low doses of a mammalian target of rapamycin inhibitor with low doses of a calcineurin inhibitor may be of benefit for autophagy modulation. However, further studies are needed to explore the role of other autophagy regulators.
    DOI:  https://doi.org/10.1097/TP.0000000000004862
  4. Autophagy. 2023 Nov 15. 1-17
    Aerobic exercise attenuates autophagy-lysosomal flux deficits by ADRB2/β2-adrenergic receptor-mediated V-ATPase assembly factor VMA21 signaling in APP-PSEN1/PS1 mice.
    Jia-Jun Wu, Haitao Yu, Shu-Guang Bi, Zhong-Xuan Wang, Juan Gong, Yu-Ming Mao, Fang-Zhou Wang, Yu-Qi Zhang, Yun-Juan Nie, Gao-Shang Chai.
      Growing evidence suggests that macroautophagy/autophagy-lysosomal pathway deficits contribute to the accumulation of amyloid-β (Aβ) in Alzheimer disease (AD). Aerobic exercise (AE) has long been investigated as an approach to delay and treat AD, although the exact role and mechanism are not well known. Here, we revealed that AE could reverse autophagy-lysosomal deficits via activation of ADRB2/β2-adrenergic receptor, leading to significant attenuation of amyloid-β pathology in APP-PSEN1/PS1 mice. Molecular mechanism research found that AE could reverse autophagy deficits by upregulating the AMP-activated protein kinase (AMPK)-MTOR (mechanistic target of rapamycin kinase) signaling pathway. Moreover, AE could reverse V-ATPase function by upregulating VMA21 levels. Inhibition of ADRB2 by propranolol (antagonist, 30 μM) blocked AE-attenuated Aβ pathology and cognitive deficits by inhibiting autophagy-lysosomal flux. AE may mitigate AD via many pathways, while ADRB2-VMA21-V-ATPase could improve cognition by enhancing the clearance of Aβ through the autophagy-lysosomal pathway, which also revealed a novel theoretical basis for AE attenuating pathological progression and cognitive deficits in AD.
    Keywords:  ADRB2; Alzheimer disease; V-ATPase; aerobic exercise; amyloid-β; autophagy
    DOI:  https://doi.org/10.1080/15548627.2023.2281134
  5. Autophagy. 2023 Nov 14. 1-4
    Ups and downs of lysosomal pH: conflicting roles of LAMP proteins?
    Jonathan Handy, Gustavo C Macintosh, Andreas Jenny.
      The acidic pH of lysosomes is critical for catabolism in eukaryotic cells and is altered in neurodegenerative disease including Alzheimer and Parkinson. Recent reports using Drosophila and mammalian cell culture systems have identified novel and, at first sight, conflicting roles for the lysosomal associated membrane proteins (LAMPs) in the regulation of the endolysosomal system.Abbreviation: AD: Alzheimer disease; LAMP: lysosomal associated membrane protein; LTR: LysoTracker; PD: Parkinson disease; TMEM175: transmembrane protein 175; V-ATPase: vacuolar-type H+-translocating ATPase.
    Keywords:  Alzheimer; Autophagy; LAMP proteins; Parkinson; lysosome; pH
    DOI:  https://doi.org/10.1080/15548627.2023.2274253
  6. bioRxiv. 2023 Oct 30. pii: 2023.10.30.564828. [Epub ahead of print]
    PDZD8 promotes autophagy at ER-Lysosome contact sites to regulate synaptogenesis.
    Rajan S Thakur, Kate M O'Connor-Giles.
      Building synaptic connections, which are often far from the soma, requires coordinating a host of cellular activities from transcription to protein turnover, placing a high demand on intracellular communication. Membrane contact sites (MCSs) formed between cellular organelles have emerged as key signaling hubs for coordinating an array of cellular activities. We have found that the endoplasmic reticulum (ER) MCS tethering protein PDZD8 is required for activity-dependent synaptogenesis. PDZD8 is sufficient to drive ectopic synaptic bouton formation through an autophagy-dependent mechanism and required for basal synapse formation when autophagy biogenesis is limited. PDZD8 functions at ER-late endosome/lysosome (LEL) MCSs to promote lysosome maturation and accelerate autophagic flux. Mutational analysis of PDZD8's SMP domain further suggests a role for lipid transfer at ER-LEL MCSs. We propose that PDZD8-dependent lipid transfer from ER to LELs promotes lysosome maturation to increase autophagic flux during periods of high demand, including activity-dependent synapse formation.GRAPHICAL ABSTRACT:
    DOI:  https://doi.org/10.1101/2023.10.30.564828
  7. medRxiv. 2023 Nov 05. pii: 2023.11.04.23297979. [Epub ahead of print]
    Autophagy gene expression in skeletal muscle of older individuals is associated with physical performance, muscle volume and mitochondrial function in the Study of Muscle, Mobility and Aging (SOMMA).
    Paul M Coen, Zhiguang Huo, Gregory J Tranah, Haley N Barnes, Peggy M Cawthon, Russell T Hepple, Frederico G S Toledo, Daniel S Evans, Olaya Santiago Fernández, Ana Maria Cuervo, Steven B Kritchevsky, Anne B Newman, Steven R Cummings, Karyn A Esser.
      Autophagy is an essential component of proteostasis and a key pathway in aging. Identifying associations between autophagy gene expression patterns in skeletal muscle and physical performance outcomes would further our knowledge of mechanisms related with proteostasis and healthy aging. Muscle biopsies were obtained from participants in the Study of Muscle, Mobility and Aging (SOMMA). For 575 participants, RNA was sequenced and expression of 281 genes related to autophagy regulation, mitophagy and mTOR/upstream pathways were determined. Associations between gene expression and outcomes including mitochondrial respiration in muscle fiber bundles (MAX OXPHOS), physical performance (VO 2 peak, 400m walking speed, and leg power), and thigh muscle volume were determined using negative binomial regression models. For autophagy, key transcriptional regulators including TFE3 and NFKB-related genes (RELA, RELB, NFKB1) were negatively associated with outcomes. On the contrary, regulators of oxidative metabolism that also promote overall autophagy, mitophagy and pexophagy (PPARGC1A, PPARA, EPAS1) were positively associated with multiple outcomes. In line with this, several mitophagy, fusion and fission related genes (NIPSNAP2, DNM1L, OPA1) were also positively associated with outcomes. For mTOR pathway and related genes, expression of WDR59 and WDR24, both subunits of GATOR2 complex (an indirect inhibitor of mTORC1) and PRKAG3, which is a regulatory subunit of AMPK, were negatively correlated with multiple outcomes. Our study identifies autophagy and selective autophagy such as mitophagy gene expression patterns in human skeletal muscle related to physical performance, muscle volume and mitochondrial function in older persons which may lead to target identification to preserve mobility and independence.
    DOI:  https://doi.org/10.1101/2023.11.04.23297979
  8. Int J Mol Sci. 2023 Nov 02. pii: 15891. [Epub ahead of print]24(21):
    Involvement of Lipophagy and Chaperone-Mediated Autophagy in the Pathogenesis of Non-Alcoholic Fatty Liver Disease by Regulation of Lipid Droplets.
    Eleftheria M Mastoridou, Anna C Goussia, Panagiotis Kanavaros, Antonia V Charchanti.
      Non-alcoholic fatty liver disease (NAFLD) is defined as the accumulation of lipids in the form of lipid droplets in more than 5% of hepatocytes. It is regarded as a range of diverse pathologies, including simple steatosis and steatohepatitis. The structural characteristics of lipid droplets, along with their protein composition, mainly including perilipins, have been implicated in the etiology of the disease. These proteins have garnered increasing attention as a pivotal regulator since their levels and distinct expression appear to be associated with the progression from simple steatosis to steatohepatitis. Perilipins are target proteins of chaperone-mediated autophagy, and their degradation is a prerequisite for lipolysis and lipophagy to access the lipid core. Both lipophagy and chaperone-mediated autophagy have significant implications on the development of the disease, as evidenced by their upregulation during the initial phases of simple steatosis and their subsequent downregulation once steatosis is established. On the contrary, during steatohepatitis, the process of chaperone-mediated autophagy is enhanced, although lipophagy remains suppressed. Evidently, the reduced levels of autophagic pathways observed in simple steatosis serve as a defensive mechanism against lipotoxicity. Conversely, in steatohepatitis, chaperone-mediated autophagy fails to compensate for the continuous generation of small lipid droplets and thus cannot protect hepatocytes from lipotoxicity.
    Keywords:  chaperone-mediated autophagy; lipophagy; non-alcoholic fatty liver disease; perilipins
    DOI:  https://doi.org/10.3390/ijms242115891
  9. Sci Data. 2023 Nov 16. 10(1): 806
    CELLULAR, A Cell Autophagy Imaging Dataset.
    Amani Al Outa, Steven Hicks, Vajira Thambawita, Siri Andresen, Jorrit M Enserink, Pål Halvorsen, Michael A Riegler, Helene Knævelsrud.
      Cells in living organisms are dynamic compartments that continuously respond to changes in their environment to maintain physiological homeostasis. While basal autophagy exists in cells to aid in the regular turnover of intracellular material, autophagy is also a critical cellular response to stress, such as nutritional depletion. Conversely, the deregulation of autophagy is linked to several diseases, such as cancer, and hence, autophagy constitutes a potential therapeutic target. Image analysis to follow autophagy in cells, especially on high-content screens, has proven to be a bottleneck. Machine learning (ML) algorithms have recently emerged as crucial in analyzing images to efficiently extract information, thus contributing to a better understanding of the questions at hand. This paper presents CELLULAR, an open dataset consisting of images of cells expressing the autophagy reporter mRFP-EGFP-Atg8a with cell-specific segmentation masks. Each cell is annotated into either basal autophagy, activated autophagy, or unknown. Furthermore, we introduce some preliminary experiments using the dataset that can be used as a baseline for future research.
    DOI:  https://doi.org/10.1038/s41597-023-02687-x
  10. Sci Rep. 2023 Nov 15. 13(1): 19958
    Conversion of methylmercury into inorganic mercury via organomercurial lyase (MerB) activates autophagy and aggresome formation.
    Yasukazu Takanezawa, Kouhei Ishikawa, Shunsuke Nakayama, Ryosuke Nakamura, Yuka Ohshiro, Shimpei Uraguchi, Masako Kiyono.
      Methylmercury (MeHg) is converted to inorganic mercury (iHg) in several organs; however, its impact on tissues and cells remains poorly understood. Previously, we established a bacterial organomercury lyase (MerB)-expressing mammalian cell line to overcome the low cell permeability of iHg and investigate its effects. Here, we elucidated the cytotoxic effects of the resultant iHg on autophagy and deciphered their relationship. Treatment of MerB-expressing cells with MeHg significantly increases the mRNA and protein levels of LC3B and p62, which are involved in autophagosome formation and substrate recognition, respectively. Autophagic flux assays using the autophagy inhibitor chloroquine (CQ) revealed that MeHg treatment activates autophagy in MerB-expressing cells but not in wild-type cells. Additionally, MeHg treatment induces the accumulation of ubiquitinated proteins and p62, specifically in MerB-expressing cells. Confocal microscopy revealed that large ubiquitinated protein aggregates (aggresomes) associated with p62 are formed transiently in the perinuclear region of MerB-expressing cells upon MeHg exposure. Meanwhile, inhibition of autophagic flux decreases the MeHg-induced cell viability of MerB-expressing cells. Overall, our results imply that cells regulate aggresome formation and autophagy activation by activating LC3B and p62 to prevent cytotoxicity caused by iHg. These findings provide insights into the role of autophagy against iHg-mediated toxicity.
    DOI:  https://doi.org/10.1038/s41598-023-47110-y
  11. Nat Commun. 2023 Nov 14. 14(1): 7364
    Targeted suppression of mTORC2 reduces seizures across models of epilepsy.
    James Okoh, Jacqunae Mays, Alexandre Bacq, Juan A Oses-Prieto, Stefka Tyanova, Chien-Ju Chen, Khalel Imanbeyev, Marion Doladilhe, Hongyi Zhou, Paymaan Jafar-Nejad, Alma Burlingame, Jeffrey Noebels, Stephanie Baulac, Mauro Costa-Mattioli.
      Epilepsy is a neurological disorder that poses a major threat to public health. Hyperactivation of mTOR complex 1 (mTORC1) is believed to lead to abnormal network rhythmicity associated with epilepsy, and its inhibition is proposed to provide some therapeutic benefit. However, mTOR complex 2 (mTORC2) is also activated in the epileptic brain, and little is known about its role in seizures. Here we discover that genetic deletion of mTORC2 from forebrain neurons is protective against kainic acid-induced behavioral and EEG seizures. Furthermore, inhibition of mTORC2 with a specific antisense oligonucleotide robustly suppresses seizures in several pharmacological and genetic mouse models of epilepsy. Finally, we identify a target of mTORC2, Nav1.2, which has been implicated in epilepsy and neuronal excitability. Our findings, which are generalizable to several models of human seizures, raise the possibility that inhibition of mTORC2 may serve as a broader therapeutic strategy against epilepsy.
    DOI:  https://doi.org/10.1038/s41467-023-42922-y
  12. Acta Pharm Sin B. 2023 Nov;13(11): 4591-4606
    Engineering cannabidiol synergistic carbon monoxide nanocomplexes to enhance cancer therapy via excessive autophagy.
    Chang Xiao, Yue Sun, Jialong Fan, William Nguyen, Simin Chen, Ying Long, Wei Chen, Aiguo Zhu, Bin Liu.
      Although carbon monoxide (CO)-based treatments have demonstrated the high cancer efficacy by promoting mitochondrial damage and core-region penetrating ability, the efficiency was often compromised by protective autophagy (mitophagy). Herein, cannabidiol (CBD) is integrated into biomimetic carbon monoxide nanocomplexes (HMPOC@M) to address this issue by inducing excessive autophagy. The biomimetic membrane not only prevents premature drugs leakage, but also prolongs blood circulation for tumor enrichment. After entering the acidic tumor microenvironment, carbon monoxide (CO) donors are stimulated by hydrogen oxide (H2O2) to disintegrate into CO and Mn2+. The comprehensive effect of CO/Mn2+ and CBD can induce ROS-mediated cell apoptosis. In addition, HMPOC@M-mediated excessive autophagy can promote cancer cell death by increasing autophagic flux via class III PI3K/BECN1 complex activation and blocking autolysosome degradation via LAMP1 downregulation. Furthermore, in vivo experiments showed that HMPOC@M+ laser strongly inhibited tumor growth and attenuated liver and lung metastases by downregulating VEGF and MMP9 proteins. This strategy may highlight the pro-death role of excessive autophagy in TNBC treatment, providing a novel yet versatile avenue to enhance the efficacy of CO treatments. Importantly, this work also indicated the applicability of CBD for triple-negative breast cancer (TNBC) therapy through excessive autophagy.
    Keywords:  Autolysosome degradation; Autophagic flux; Cannabidiol; Carbon monoxide therapy; Excessive autophagy; Metastases; Reactive oxygen species; Triple-negative breast cancer
    DOI:  https://doi.org/10.1016/j.apsb.2023.05.019
  13. Nat Commun. 2023 Nov 13. 14(1): 7338
    Local membrane source gathering by p62 body drives autophagosome formation.
    Xuezhao Feng, Daxiao Sun, Yanchang Li, Jinpei Zhang, Shiyu Liu, Dachuan Zhang, Jingxiang Zheng, Qing Xi, Haisha Liang, Wenkang Zhao, Ying Li, Mengbo Xu, Jiayu He, Tong Liu, Ayshamgul Hasim, Meisheng Ma, Ping Xu, Na Mi.
      Autophagosomes are double-membrane vesicles generated intracellularly to encapsulate substrates for lysosomal degradation during autophagy. Phase separated p62 body plays pivotal roles during autophagosome formation, however, the underlying mechanisms are still not fully understood. Here we describe a spatial membrane gathering mode by which p62 body functions in autophagosome formation. Mass spectrometry-based proteomics reveals significant enrichment of vesicle trafficking components within p62 body. Combining cellular experiments and biochemical reconstitution assays, we confirm the gathering of ATG9 and ATG16L1-positive vesicles around p62 body, especially in Atg2ab DKO cells with blocked lipid transfer and vesicle fusion. Interestingly, p62 body also regulates ATG9 and ATG16L vesicle trafficking flux intracellularly. We further determine the lipid contents associated with p62 body via lipidomic profiling. Moreover, with in vitro kinase assay, we uncover the functions of p62 body as a platform to assemble ULK1 complex and invigorate PI3KC3-C1 kinase cascade for PI3P generation. Collectively, our study raises a membrane-based working model for multifaceted p62 body in controlling autophagosome biogenesis, and highlights the interplay between membraneless condensates and membrane vesicles in regulating cellular functions.
    DOI:  https://doi.org/10.1038/s41467-023-42829-8
  14. FASEB J. 2023 12;37(12): e23289
    Activation of moderate autophagy promotes survival of fat graft.
    Su-Jun Pei, Yuan-Zheng Zhu, Juan-Min Yang, Min-Chen Zhang, Chen-Long Shi, Ying Ding, Yang-Yan Yi.
      Clinically unpredictable retention following fat grafting remains outstanding problems because of the unrevealed mechanism of grafted fat survival. The role of autophagy, a process to maintain cellular homeostasis through recycling cellular debris, has yet been to be reported in fat grafting. This study aims to improve the survival of fat grafting through the autophagy. First, the relationship between cell death and autophagy in the early stage of fat grafting was evaluated through immunostaining, RNA sequencing, and western blot. Next, rapamycin, an autophagic agonist, was used for the culturing of adipose-derived stem cells and adipocytes during ischemia. Cell death, autophagy, and reactive oxygen species (ROS) were assayed. Finally, rapamycin was used to assist fat grafting in nude mice. The results demonstrated that the peak of cell death at the early stage of fat grafting was accompanied by a decrease in autophagy. In vitro, during ischemia, 25 nM was confirmed as the optimal dose of rapamycin that reduces cell death with enhanced autophagy and mitophagy, improved mitochondrial quality as well as decreased ROS accumulation. In vivo, promoted mitophagy, alleviated oxidative stress, and decreased cell apoptosis of rapamycin-treated fat grafts were observed in the early stage. In addition, rapamycin increased the survival of fat grafts with increased neovascularization and reduced fibrosis. We suggested that moderate autophagy induced by rapamycin contribute to enhanced ischemic tolerance and long term survival of fat grafts through mitochondrial quality control.
    Keywords:  autophagy; fat grafting; ischemic tolerance; mitochondrial quality control; mitophagy
    DOI:  https://doi.org/10.1096/fj.202300892R
  15. Nat Aging. 2023 Nov 13.
    A drug-like molecule engages nuclear hormone receptor DAF-12/FXR to regulate mitophagy and extend lifespan.
    Manish Chamoli, Anand Rane, Anna Foulger, Shankar J Chinta, Azar Asadi Shahmirzadi, Caroline Kumsta, Dhanya K Nambiar, David Hall, Angelina Holcom, Suzanne Angeli, Minna Schmidt, Sharon Pitteri, Malene Hansen, Gordon J Lithgow, Julie K Andersen.
      Autophagy-lysosomal function is crucial for maintaining healthy lifespan and preventing age-related diseases. The transcription factor TFEB plays a key role in regulating this pathway. Decreased TFEB expression is associated with various age-related disorders, making it a promising therapeutic target. In this study, we screened a natural product library and discovered mitophagy-inducing coumarin (MIC), a benzocoumarin compound that enhances TFEB expression and lysosomal function. MIC robustly increases the lifespan of Caenorhabditis elegans in an HLH-30/TFEB-dependent and mitophagy-dependent manner involving DCT-1/BNIP3 while also preventing mitochondrial dysfunction in mammalian cells. Mechanistically, MIC acts by inhibiting ligand-induced activation of the nuclear hormone receptor DAF-12/FXR, which, in turn, induces mitophagy and extends lifespan. In conclusion, our study uncovers MIC as a promising drug-like molecule that enhances mitochondrial function and extends lifespan by targeting DAF-12/FXR. Furthermore, we discovered DAF-12/FXR as a previously unknown upstream regulator of HLH-30/TFEB and mitophagy.
    DOI:  https://doi.org/10.1038/s43587-023-00524-9
  16. bioRxiv. 2023 Oct 27. pii: 2023.10.27.564376. [Epub ahead of print]
    SCD1 and monounsaturated lipids are required for autophagy and survival of adipocytes.
    Hiroyuki Mori, Sydney K Peterson, Rachel Simmermon, Katherine A Overmyer, Akira Nishii, Emma Paulsson, Ziru Li, Annie Jen, Romina M Uranga, Jessica Maung, Warren T Yacawych, Kenneth T Lewis, Rebecca L Schill, Taryn Hetrick, Ryo Seino, Ken Inoki, Joshua J Coon, Ormond A MacDougald.
      Exposure of adipocytes to 'cool' temperatures often found in the periphery of the body induces expression of Stearoyl-CoA Desaturase-1 (SCD1), an enzyme that converts saturated fatty acids to monounsaturated fatty acids. In this study, we employed Scd1 knockout cells and mouse models, along with pharmacological SCD1 inhibition, to investigate further the roles of SCD1 in adipocytes. Our study reveals that production of monounsaturated lipids by SCD1 is necessary for fusion of autophagosomes to lysosomes and that with a SCD1-deficiency, autophagosomes accumulate. In addition, SCD1-deficiency impairs lysosomal and autolysosomal acidification resulting in vacuole accumulation and eventual cell death. Blocking autophagosome formation or supplementation with monounsaturated fatty acids maintains vitality of SCD1-deficient adipocytes. Taken together, our results demonstrate that in vitro inhibition of SCD1 in adipocytes leads to autophagy-dependent cell death, and in vivo depletion leads to loss of bone marrow adipocytes.
    DOI:  https://doi.org/10.1101/2023.10.27.564376
  17. Mol Neurodegener. 2023 Nov 16. 18(1): 87
    Multi-modal proteomic characterization of lysosomal function and proteostasis in progranulin-deficient neurons.
    Saadia Hasan, Michael S Fernandopulle, Stewart W Humble, Ashley M Frankenfield, Haorong Li, Ryan Prestil, Kory R Johnson, Brent J Ryan, Richard Wade-Martins, Michael E Ward, Ling Hao.
      BACKGROUND: Progranulin (PGRN) is a lysosomal glycoprotein implicated in various neurodegenerative diseases, including frontotemporal dementia and neuronal ceroid lipofuscinosis. Over 70 mutations discovered in the GRN gene all result in reduced expression of the PGRN protein. Genetic and functional studies point toward a regulatory role for PGRN in lysosome functions. However, the detailed molecular function of PGRN within lysosomes and the impact of PGRN deficiency on lysosomes remain unclear.METHODS: We developed multifaceted proteomic techniques to characterize the dynamic lysosomal biology in living human neurons and fixed mouse brain tissues. Using lysosome proximity labeling and immuno-purification of intact lysosomes, we characterized lysosome compositions and interactome in both human induced pluripotent stem cell (iPSC)-derived glutamatergic neurons (i3Neurons) and mouse brains. Using dynamic stable isotope labeling by amino acids in cell culture (dSILAC) proteomics, we measured global protein half-lives in human i3Neurons for the first time.
    RESULTS: Leveraging the multi-modal proteomics and live-cell imaging techniques, we comprehensively characterized how PGRN deficiency changes the molecular and functional landscape of neuronal lysosomes. We found that PGRN loss impairs the lysosome's degradative capacity with increased levels of v-ATPase subunits on the lysosome membrane, increased hydrolases within the lysosome, altered protein regulations related to lysosomal transport, and elevated lysosomal pH. Consistent with impairments in lysosomal function, GRN-null i3Neurons and frontotemporal dementia patient-derived i3Neurons carrying GRN mutation showed pronounced alterations in protein turnover, such as cathepsins and proteins related to supramolecular polymerization and inherited neurodegenerative diseases.
    CONCLUSION: This study suggested PGRN as a critical regulator of lysosomal pH and degradative capacity, which influences global proteostasis in neurons. Beyond the study of progranulin deficiency, these newly developed proteomic methods in neurons and brain tissues provided useful tools and data resources for the field to study the highly dynamic neuronal lysosome biology.
    Keywords:  Frontotemporal dementia; Half-life; Lysosome; Neuron; PGRN; Progranulin; Proteomics; Turnover; dSILAC; iPSC
    DOI:  https://doi.org/10.1186/s13024-023-00673-w
  18. Acta Pharm Sin B. 2023 Nov;13(11): 4373-4390
    Drug discovery by targeting the protein-protein interactions involved in autophagy.
    Honggang Xiang, Mi Zhou, Yan Li, Lu Zhou, Renxiao Wang.
      Autophagy is a cellular process in which proteins and organelles are engulfed in autophagosomal vesicles and transported to the lysosome/vacuole for degradation. Protein-protein interactions (PPIs) play a crucial role at many stages of autophagy, which present formidable but attainable targets for autophagy regulation. Moreover, selective regulation of PPIs tends to have a lower risk in causing undesired off-target effects in the context of a complicated biological network. Thus, small-molecule regulators, including peptides and peptidomimetics, targeting the critical PPIs involved in autophagy provide a new opportunity for innovative drug discovery. This article provides general background knowledge of the critical PPIs involved in autophagy and reviews a range of successful attempts on discovering regulators targeting those PPIs. Successful strategies and existing limitations in this field are also discussed.
    Keywords:  Autophagy regulation; Drug discovery; Protein–protein interactions; Small-molecule regulators
    DOI:  https://doi.org/10.1016/j.apsb.2023.07.016
  19. Aging Dis. 2023 Sep 14.
    Autophagy in Disease Onset and Progression.
    Hao Wang, Xiushen Li, Qi Zhang, Chengtao Fu, Wenjie Jiang, Jun Xue, Shan Liu, Qingxue Meng, Lisha Ai, Xuejun Zhi, Shoulong Deng, Weizheng Liang.
      Autophagy is a biological phenomenon whereby components of cells can self-degrade using autophagosomes. During this process, cells can clear dysfunctional organelles or unwanted elements. Autophagy can recycle unnecessary biomolecules into new components or sometimes, even destroy the cells themselves. This cellular process was first observed in 1962 by Keith R. Porter et al. Since then, autophagy has been studied for over 60 years, and much has been learned on the topic. Nevertheless, the process is still not fully understood. It has been proven, for example, that autophagy can be a positive force for maintaining good health by removing older or damaged cells. By contrast, autophagy is also involved in the onset and progression of various conditions caused by pathogenic infections. These diseases generally involve several important organs in the human body, including the liver, kidney, heart, and central nervous system. The regulation of the defects of autophagy defects may potentially be used to treat some diseases. This review comprehensively discusses recent research frontiers and topics of interest regarding autophagy-related diseases.
    DOI:  https://doi.org/10.14336/AD.2023.0815
  20. Oncogenesis. 2023 Nov 13. 12(1): 54
    Kinesin family member 18B activates mTORC1 signaling via actin gamma 1 to promote the recurrence of human hepatocellular carcinoma.
    Qian Li, Mengqing Sun, Yao Meng, Mengqing Feng, Menglan Wang, Cunjie Chang, Heng Dong, Fangtian Bu, Chao Xu, Jing Liu, Qi Ling, Yiting Qiao, Jianxiang Chen.
      The mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway is frequently reported to be hyperactivated in hepatocellular carcinoma (HCC) and contributes to HCC recurrence. However, the underlying regulatory mechanisms of mTORC1 signaling in HCC are not fully understood. In the present study, we found that the expression of kinesin family member 18B (KIF18B) was positively correlated with mTORC1 signaling in HCC, and the upregulation of KIF18B and p-mTOR was associated with a poor prognosis and HCC recurrence. Utilizing in vitro and in vivo assays, we showed that KIF18B promoted HCC cell proliferation and migration through activating mTORC1 signaling. Mechanistically, we identified Actin gamma 1 (γ-Actin) as a binding partner of KIF18B. KIF18B and γ-Actin synergistically modulated lysosome positioning, promoted mTORC1 translocation to lysosome membrane, and prohibited p70 S6K from entering lysosomes for degradation, which finally led to the enhancement of mTORC1 signaling transduction. Moreover, we found that KIF18B was a direct target of Forkhead box M1, which explains the potential mechanism of KIF18B overexpression in HCC. Our study highlights the potential of KIF18B as a therapeutic target for the treatment of HCC.
    DOI:  https://doi.org/10.1038/s41389-023-00499-7
  21. Front Neurosci. 2023 ;17 1299552
    Role of mitophagy in ocular neurodegeneration.
    Calvin D Brooks, Bindu Kodati, Dorota L Stankowska, Raghu R Krishnamoorthy.
      Neurons in the central nervous system are among the most metabolically active cells in the body, characterized by high oxygen consumption utilizing glucose both aerobically and anaerobically. Neurons have an abundance of mitochondria which generate adequate ATP to keep up with the high metabolic demand. One consequence of the oxidative phosphorylation mechanism of ATP synthesis, is the generation of reactive oxygen species which produces cellular injury as well as damage to mitochondria. Mitochondria respond to injury by fusion which serves to ameliorate the damage through genetic complementation. Mitochondria also undergo fission to meet an increased energy demand. Loss of mitochondria is also compensated by increased biogenesis to generate new mitochondria. Damaged mitochondria are removed by mitophagy, an autophagic process, in which damaged mitochondria are surrounded by a membrane to form an autophagosome which ultimately fuses with the lysosome resulting in degradation of faulty mitochondria. Dysregulation of mitophagy has been reported in several central nervous system disorders, including, Alzheimer's disease and Parkinson's disease. Recent studies point to aberrant mitophagy in ocular neurodegenerative disorders which could be an important contributor to the disease etiology/pathology. This review article highlights some of the recent findings that point to dysregulation of mitophagy and it's underlying mechanisms in ocular neurodegenerative diseases, including, glaucoma, age-related macular degeneration and diabetic retinopathy.
    Keywords:  age-related macular degeneration; diabetic retinopathy; glaucoma; mitochondria; mitophagy; neurodegeneration
    DOI:  https://doi.org/10.3389/fnins.2023.1299552
  22. bioRxiv. 2023 Nov 03. pii: 2023.10.31.564991. [Epub ahead of print]
    Autophagy regulates tumor growth and metastasis.
    Lei Qiang, Baozhong Zhao, Mei Ming, Ning Wang, Tong-Chuan He, Seungmin Hwang, Andrew Thorburn, Yu-Ying He.
      The role of autophagy in tumorigenesis and tumor metastasis remains poorly understood. Here we show that inhibition of autophagy stabilizes the transcription factor Twist1 through Sequestosome-1 (SQSTM1, also known as p62) and thus increases cell proliferation, migration, and epithelial-mesenchymal transition (EMT) in tumor development and metastasis. Inhibition of autophagy or p62 overexpression blocks Twist1 protein degradation in the proteasomes, while p62 inhibition enhances it. SQSTM1/p62 interacts with Twist1 via the UBA domain of p62, in a Twist1-ubiquitination-dependent manner. Lysine 175 in Twist1 is critical for Twist1 ubiquitination, degradation, and SQSTM1/p62 interaction. For squamous skin cancer and melanoma cells that express Twist1, SQSTM1/p62 increases tumor growth and metastasis in mice. Together, our results identified Twist1 as a key downstream protein for autophagy and suggest a critical role of the autophagy/p62/Twist1 axis in cancer development and metastasis.
    DOI:  https://doi.org/10.1101/2023.10.31.564991
  23. J Exp Bot. 2023 Nov 18. pii: erad459. [Epub ahead of print]
    New Insights into Plant Autophagy: Molecular Mechanisms and Roles in Development and Stress Responses.
    Mako Yagyu, Kohki Yoshimoto.
      Autophagy is an evolutionarily conserved eukaryotic intracellular degradation process. Although the molecular mechanisms of plant autophagy share similarities with those in yeast and mammals, certain unique mechanisms have been identified. Recent studies have highlighted the importance of autophagy during vegetative growth stages as well as in plant-specific developmental processes, such as seed development, germination, flowering, and somatic reprogramming. Autophagy enables plants to adapt to and manage severe environmental conditions, such as nutrient starvation, high-intensity light stress and heat stress, leading to intracellular remodeling and physiological changes in response to stress. In the past, plant autophagy research lagged behind similar studies in yeast and mammals; however, recent advances have greatly expanded our understanding of plant-specific autophagy mechanisms and functions. This review summarizes the current state of knowledge and latest research findings on the mechanisms and roles of plant autophagy with the objective of improving our understanding of this vital process in plants.
    Keywords:  Autophagosome formation; Development; Macroautophagy; Mega-autophagy; Microautophagy; Organelle; Plant; Stress; Vacuole
    DOI:  https://doi.org/10.1093/jxb/erad459
  24. Cell Death Dis. 2023 11 11. 14(11): 735
    Integration of FUNDC1-associated mitochondrial protein import and mitochondrial quality control contributes to TDP-43 degradation.
    Jinfa Ma, Lei Liu, Lu Song, Jianghong Liu, Lingyao Yang, Quan Chen, Jane Y Wu, Li Zhu.
      Though TDP-43 protein can be translocated into mitochondria and causes mitochondrial damage in TDP-43 proteinopathy, little is known about how TDP-43 is imported into mitochondria. In addition, whether mitochondrial damage is caused by mitochondrial mislocalization of TDP-43 or a side effect of mitochondria-mediated TDP-43 degradation remains to be investigated. Here, our bioinformatical analyses reveal that mitophagy receptor gene FUNDC1 is co-expressed with TDP-43, and both TDP-43 and FUNDC1 expression is correlated with genes associated with mitochondrial protein import pathway in brain samples of patients diagnosed with TDP-43 proteinopathy. FUNDC1 promotes mitochondrial translocation of TDP-43 possibly by promoting TDP-43-TOM70 and DNAJA2-TOM70 interactions, which is independent of the LC3 interacting region of FUNDC1 in cellular experiments. In the transgenic fly model of TDP-43 proteinopathy, overexpressing FUNDC1 enhances TDP-43 induced mitochondrial damage, whereas down-regulating FUNDC1 reverses TDP-43 induced mitochondrial damage. FUNDC1 regulates mitochondria-mediated TDP-43 degradation not only by regulating mitochondrial TDP-43 import, but also by increasing LONP1 level and by activating mitophagy, which plays important roles in cytosolic TDP-43 clearance. Together, this study not only uncovers the mechanism of mitochondrial TDP-43 import, but also unravels the active role played by mitochondria in regulating TDP-43 homeostasis.
    DOI:  https://doi.org/10.1038/s41419-023-06261-6
  25. Cancer Lett. 2023 Nov 15. pii: S0304-3835(23)00433-0. [Epub ahead of print] 216482
    Autophagy machinery in glioblastoma: The prospect of cell death crosstalk and drug resistance with bioinformatics analysis.
    Yi Qin, Shengjun Xiong, Jun Ren, Gautam Sethi.
      Brain tumors are common malignancies with high mortality and morbidity in which glioblastoma (GB) is a grade IV astrocytoma with heterogeneous nature. The conventional therapeutics for the GB mainly include surgery and chemotherapy, however their efficacy has been compromised due to the aggressiveness of tumor cells. The dysregulation of cell death mechanisms, especially autophagy has been reported as a factor causing difficulties in cancer therapy. As a mechanism contributing to cell homeostasis, the autophagy process is hijacked by tumor cells for the purpose of aggravating cancer progression and drug resistance. The autophagy function is context-dependent and its role can be lethal or protective in cancer. The aim of the current paper is to highlight the role of autophagy in the regulation of GB progression. The cytotoxic function of autophagy can promote apoptosis and ferroptosis in GB cells and vice versa. Autophagy dysregulation can cause drug resistance and radioresistance in GB. Moreover, stemness can be regulated by autophagy and overall growth as well as metastasis are affected by autophagy. The various interventions including administration of synthetic/natural products and nanoplatforms can target autophagy. Therefore, autophagy can act as a promising target in GB therapy.
    Keywords:  Apoptosis; Autophagy; Chemoresistance; Glioblastoma; Stemness
    DOI:  https://doi.org/10.1016/j.canlet.2023.216482
  26. Neurochem Res. 2023 Nov 13.
    Restraint Stress, Foot Shock and Corticosterone Differentially Alter Autophagy in the Rat Hippocampus, Basolateral Amygdala and Prefrontal Cortex.
    Yanmei Chen, Xiaotao Zhou, Boling Chu, Qunqun Xie, Zhenkun Liu, Di Luo, Jichuan Zhang.
      Autophagy is a conserved lysosomal degradation process that has recently been found to be associated with stress-related psychological diseases. However, previous studies have yielded inconsistent results regarding the effects of various stress patterns on autophagy in different brain regions. This discrepancy may arise from differences in autophagy flux across nuclei, the type of stress experienced, and the timing of autophagy assessment after stress exposure. In this study, we assessed autophagy flux in the rat hippocampus (HPC), medial prefrontal cortex (mPFC), and basal lateral amygdala (BLA) by quantifying protein levels of p-ULK1, LC3-I, LC3-II, and p62 via Western blot analysis at 15 min, 30 min, and 60 min following various stress paradigms: restraint stress, foot shock, single corticosterone injection, and chronic corticosterone treatment. We found that: (1) hippocampal autophagy decreased within 1 h of restraint stress, foot shock, and corticosterone injection, except for a transient increase at 30 min after restraint stress; (2) autophagy increased 1 h after restraint stress and corticosterone injection but decreased 1 h after foot shock in mPFC; (3) In BLA, autophagy increased 1 h after foot shock and corticosterone injection but decreased 1 h after restraint stress; (4) Chronic corticosterone increased autophagy in mPFC and BLA but had no effects in HPC. These findings suggest that stress regulates autophagy in a brain region- and stressor-specific manner within 1 h after stress exposure, which may contribute to the development of stress-related psychological disorders.
    Keywords:  Autophagy; BLA; Hippocampus; Stress; mPFC
    DOI:  https://doi.org/10.1007/s11064-023-04048-x
  27. Cell Death Dis. 2023 Nov 15. 14(11): 744
    mTOR inhibition suppresses salinomycin-induced ferroptosis in breast cancer stem cells by ironing out mitochondrial dysfunctions.
    Emma Cosialls, Emeline Pacreau, Clémence Duruel, Sara Ceccacci, Rima Elhage, Christophe Desterke, Kevin Roger, Chiara Guerrera, Romane Ducloux, Sylvie Souquere, Gérard Pierron, Ivan Nemazanyy, Mairead Kelly, Elise Dalmas, Yunhua Chang, Vincent Goffin, Maryam Mehrpour, Ahmed Hamaï.
      Ferroptosis constitutes a promising therapeutic strategy against cancer by efficiently targeting the highly tumorigenic and treatment-resistant cancer stem cells (CSCs). We previously showed that the lysosomal iron-targeting drug Salinomycin (Sal) was able to eliminate CSCs by triggering ferroptosis. Here, in a well-established breast CSCs model (human mammary epithelial HMLER CD24low/CD44high), we identified that pharmacological inhibition of the mechanistic target of rapamycin (mTOR), suppresses Sal-induced ferroptosis. Mechanistically, mTOR inhibition modulates iron cellular flux and thereby limits iron-mediated oxidative stress. Furthermore, integration of multi-omics data identified mitochondria as a key target of Sal action, leading to profound functional and structural alteration prevented by mTOR inhibition. On top of that, we found that Sal-induced metabolic plasticity is mainly dependent on the mTOR pathway. Overall, our findings provide experimental evidence for the mechanisms of mTOR as a crucial effector of Sal-induced ferroptosis pointing not only that metabolic reprogramming regulates ferroptosis, but also providing proof-of-concept that careful evaluation of such combination therapy (here mTOR and ferroptosis co-targeting) is required in the development of an effective treatment.
    DOI:  https://doi.org/10.1038/s41419-023-06262-5
  28. Int J Mol Sci. 2023 Oct 30. pii: 15745. [Epub ahead of print]24(21):
    TOR Complex 1: Orchestrating Nutrient Signaling and Cell Cycle Progression.
    Magdalena Foltman, Alberto Sanchez-Diaz.
      The highly conserved TOR signaling pathway is crucial for coordinating cellular growth with the cell cycle machinery in eukaryotes. One of the two TOR complexes in budding yeast, TORC1, integrates environmental cues and promotes cell growth. While cells grow, they need to copy their chromosomes, segregate them in mitosis, divide all their components during cytokinesis, and finally physically separate mother and daughter cells to start a new cell cycle apart from each other. To maintain cell size homeostasis and chromosome stability, it is crucial that mechanisms that control growth are connected and coordinated with the cell cycle. Successive periods of high and low TORC1 activity would participate in the adequate cell cycle progression. Here, we review the known molecular mechanisms through which TORC1 regulates the cell cycle in the budding yeast Saccharomyces cerevisiae that have been extensively used as a model organism to understand the role of its mammalian ortholog, mTORC1.
    Keywords:  S. cerevisiae; TOR; TORC1; budding yeast; cell cycle; cell growth
    DOI:  https://doi.org/10.3390/ijms242115745
  29. Neurobiol Aging. 2023 Sep 28. pii: S0197-4580(23)00233-6. [Epub ahead of print]134 9-20
    Role and molecular regulatory mechanisms of Hippo signaling pathway in Caenorhabditis elegans and mammalian cell models of Alzheimer's disease.
    Man Zhu, Huan Gu, Hua Bai, Yixin Li, Chidi Zhong, Xiaowei Huang.
      Although there is increasing evidence for the involvement of Hippo signaling in Alzheimer's disease (AD), the detailed functions and regulatory mechanisms are not fully understood, given the diverse biological effects of this pathway. In the present work, we used Caenorhabditis elegans and mammalian cell models to investigate changes in the Hippo signaling pathway in response to Aβ and the downstream effects on AD development. Aβ1-42 production in the AD models decreased phosphorylation of the upstream CST-1/WTS-1 kinase cascade and promoted an interaction between LIN-10 and YAP-1, leading to the nuclear translocation of YAP-1 and inducing gene transcription in conjunction with the transcription factor EGL-44. The YAP-1/EGL-44 complex suppressed the autophagy-lysosome pathway by modulating mTOR signaling, which enhanced Aβ1-42 accumulation and promoted AD progression. These results demonstrate for the first time that crosstalk between Hippo and mTOR signaling contributes to AD development by enhancing Aβ production, resulting in inhibition of Hippo signaling and autophagy-lysosome pathway and Aβ accumulation, suggesting potential therapeutic targets for the treatment or prevention of AD.
    Keywords:  Alzheimer’s disease; Autophagy-lysosome pathway; Caenorhabditis elegans; Hippo pathway; LIN-10
    DOI:  https://doi.org/10.1016/j.neurobiolaging.2023.09.015
  30. Adv Sci (Weinh). 2023 Nov 15. e2303489
    Branched-Chain Amino Acid Accumulation Fuels the Senescence-Associated Secretory Phenotype.
    Yaosi Liang, Christopher Pan, Tao Yin, Lu Wang, Xia Gao, Ergang Wang, Holly Quang, De Huang, Lianmei Tan, Kun Xiang, Yu Wang, Peter B Alexander, Qi-Jing Li, Tso-Pang Yao, Zhao Zhang, Xiao-Fan Wang.
      The essential branched-chain amino acids (BCAAs) leucine, isoleucine, and valine play critical roles in protein synthesis and energy metabolism. Despite their widespread use as nutritional supplements, BCAAs' full effects on mammalian physiology remain uncertain due to the complexities of BCAA metabolic regulation. Here a novel mechanism linking intrinsic alterations in BCAA metabolism is identified to cellular senescence and the senescence-associated secretory phenotype (SASP), both of which contribute to organismal aging and inflammation-related diseases. Altered BCAA metabolism driving the SASP is mediated by robust activation of the BCAA transporters Solute Carrier Family 6 Members 14 and 15 as well as downregulation of the catabolic enzyme BCAA transaminase 1 during onset of cellular senescence, leading to highly elevated intracellular BCAA levels in senescent cells. This, in turn, activates the mammalian target of rapamycin complex 1 (mTORC1) to establish the full SASP program. Transgenic Drosophila models further indicate that orthologous BCAA regulators are involved in the induction of cellular senescence and age-related phenotypes in flies, suggesting evolutionary conservation of this metabolic pathway during aging. Finally, experimentally blocking BCAA accumulation attenuates the inflammatory response in a mouse senescence model, highlighting the therapeutic potential of modulating BCAA metabolism for the treatment of age-related and inflammatory diseases.
    Keywords:  BCAA; SASP; age-related inflammation; mTORC1; senescence
    DOI:  https://doi.org/10.1002/advs.202303489
  31. Nat Commun. 2023 Nov 13. 14(1): 7295
    Knockout or inhibition of USP30 protects dopaminergic neurons in a Parkinson's disease mouse model.
    Tracy-Shi Zhang Fang, Yu Sun, Andrew C Pearce, Simona Eleuteri, Mark Kemp, Christopher A Luckhurst, Rachel Williams, Ross Mills, Sarah Almond, Laura Burzynski, Nóra M Márkus, Christopher J Lelliott, Natasha A Karp, David J Adams, Stephen P Jackson, Jin-Feng Zhao, Ian G Ganley, Paul W Thompson, Gabriel Balmus, David K Simon.
      Mutations in SNCA, the gene encoding α-synuclein (αSyn), cause familial Parkinson's disease (PD) and aberrant αSyn is a key pathological hallmark of idiopathic PD. This α-synucleinopathy leads to mitochondrial dysfunction, which may drive dopaminergic neurodegeneration. PARKIN and PINK1, mutated in autosomal recessive PD, regulate the preferential autophagic clearance of dysfunctional mitochondria ("mitophagy") by inducing ubiquitylation of mitochondrial proteins, a process counteracted by deubiquitylation via USP30. Here we show that loss of USP30 in Usp30 knockout mice protects against behavioral deficits and leads to increased mitophagy, decreased phospho-S129 αSyn, and attenuation of SN dopaminergic neuronal loss induced by αSyn. These observations were recapitulated with a potent, selective, brain-penetrant USP30 inhibitor, MTX115325, with good drug-like properties. These data strongly support further study of USP30 inhibition as a potential disease-modifying therapy for PD.
    DOI:  https://doi.org/10.1038/s41467-023-42876-1
  32. Zool Res. 2023 Nov 18. pii: 2095-8137(2023)06-1132-14. [Epub ahead of print]44(6): 1132-1145
    Targeting autophagy in Alzheimer's disease: Animal models and mechanisms.
    Xiao-Wen Zhang, Xiang-Xing Zhu, Dong-Sheng Tang, Jia-Hong Lu.
      Alzheimer's disease (AD) is an age-related progressive neurodegenerative disorder that leads to cognitive impairment and memory loss. Emerging evidence suggests that autophagy plays an important role in the pathogenesis of AD through the regulation of amyloid-beta (Aβ) and tau metabolism, and that autophagy dysfunction exacerbates amyloidosis and tau pathology. Therefore, targeting autophagy may be an effective approach for the treatment of AD. Animal models are considered useful tools for investigating the pathogenic mechanisms and therapeutic strategies of diseases. This review aims to summarize the pathological alterations in autophagy in representative AD animal models and to present recent studies on newly discovered autophagy-stimulating interventions in animal AD models. Finally, the opportunities, difficulties, and future directions of autophagy targeting in AD therapy are discussed.
    Keywords:  Alzheimer’s disease; Animal models; Autophagy; Aβ metabolism; Tau pathology
    DOI:  https://doi.org/10.24272/j.issn.2095-8137.2023.294
  33. Cell Signal. 2023 Nov 10. pii: S0898-6568(23)00383-2. [Epub ahead of print]113 110968
    CTCF modulates adipocyte lipolysis via directly regulating the expression of Beclin 1 with the cooperation of PPARγ.
    Haorui Qin, Zhiqiang Han, Wenkai Zhang, Rongquan He, Shuhua Zeng, Chunhui Qi, Shuting Zhou, Yingchun Chen.
      Dysregulated lipolysis is a risk factor contributing to metabolic diseases and autophagy is known to be important in lipolysis. CTCF is involved in diverse cellular processes including adipogenesis, yet its role in lipolysis or autophagy remains unknown. We identified lipolytic genes were downregulated in CTCF knockdown adipocytes based on the RNA-seq data. Further validation showed that CTCF knockdown restrained adipocyte lipolysis while overexpression of CTCF had opposite effects. Similarly, overexpression and knockdown studies demonstrated that CTCF was a positive regulator of autophagy. Treatment with autophagy inducer relieved the suppression of lipolysis caused by CTCF knockdown, while autophagy inhibitor treatment alleviated lipolysis stimulated by CTCF overexpression, indicating that CTCF regulates adipocyte lipolysis through autophagy. Mechanistically, CTCF interacted with PPARγ to coordinately enhanced lipolytic capacity. Data of chip-seq, chip-qPCR and further experiments confirmed that CTCF and PPARγ separately stimulated transactivation of autophagy regulatory protein Beclin 1, while co-expression of the two displayed synergistic effects to regulate autophagy flux. Expectedly, overexpression of Beclin 1 abolished the blockage of lipolysis and autophagy caused by CTCF knockdown. Collectively, CTCF cooperates with PPARγ to regulate autophagy via directly modulating BECLIN 1 transcription, thereby leading to increased adipocyte lipolysis.
    Keywords:  Autophagy; Beclin 1; CTCF; Lipolysis; PPARγ
    DOI:  https://doi.org/10.1016/j.cellsig.2023.110968
  34. Autophagy. 2023 Nov 14. 1-16
    Pycard deficiency inhibits microRNA maturation and prevents neointima formation by promoting chaperone-mediated autophagic degradation of AGO2/argonaute 2 in adipose tissue.
    Jian Li, Hongmin Yao, Fujie Zhao, Junqing An, Qilong Wang, Jing Mu, Zhixue Liu, Ming-Hui Zou, Zhonglin Xie.
      PYCARD (PYD and CARD domain containing), a pivotal adaptor protein in inflammasome assembly and activation, contributes to innate immunity, and plays an essential role in the pathogenesis of atherosclerosis and restenosis. However, its roles in microRNA biogenesis remain unknown. Therefore, this study aimed to investigate the roles of PYCARD in miRNA biogenesis and neointima formation using pycard knockout (pycard-/-) mice. Deficiency of Pycard reduced circulating miRNA profile and inhibited Mir17 seed family maturation. The systemic pycard knockout also selectively reduced the expression of AGO2 (argonaute RISC catalytic subunit 2), an important enzyme in regulating miRNA biogenesis, by promoting chaperone-mediated autophagy (CMA)-mediated degradation of AGO2, specifically in adipose tissue. Mechanistically, pycard knockout increased PRMT8 (protein arginine N-methyltransferase 8) expression in adipose tissue, which enhanced AGO2 methylation, and subsequently promoted its binding to HSPA8 (heat shock protein family A (Hsp70) member 8) that targeted AGO2 for lysosome degradation through chaperone-mediated autophagy. Finally, the reduction of AGO2 and Mir17 family expression prevented vascular injury-induced neointima formation in Pycard-deficient conditions. Overexpression of AGO2 or administration of mimic of Mir106b (a major member of the Mir17 family) prevented Pycard deficiency-mediated inhibition of neointima formation in response to vascular injury. These data demonstrate that PYCARD inhibits CMA-mediated degradation of AGO2, which promotes microRNA maturation, thereby playing a critical role in regulating neointima formation in response to vascular injury independently of inflammasome activity and suggest that modulating PYCARD expression and function may represent a powerful therapeutic strategy for neointima formation.Abbreviations: 6-AN: 6-aminonicotinamide; ACTB: actin, beta; aDMA: asymmetric dimethylarginine; AGO2: argonaute RISC catalytic subunit 2; CAL: carotid artery ligation; CALCOCO2: calcium binding and coiled-coil domain 2; CMA: chaperone-mediated autophagy; CTSB: cathepsin B; CTSD: cathepsin D; DGCR8: DGCR8 microprocessor complex subunit; DOCK2: dedicator of cyto-kinesis 2; EpiAdi: epididymal adipose tissue; HSPA8: heat shock protein family A (Hsp70) member 8; IHC: immunohistochemical; ISR: in-stent restenosis; KO: knockout; LAMP2: lysosomal-associated membrane protein 2; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; miRNA: microRNA; NLRP3: NLR family pyrin domain containing 3; N/L: ammonium chloride combined with leupeptin; PRMT: protein arginine methyltransferase; PVAT: peri-vascular adipose tissues; PYCARD: PYD and CARD domain containing; sDMA: symmetric dimethylarginine; ULK1: unc-51 like kinase 1; VSMCs: vascular smooth muscle cells; WT: wild-type.
    Keywords:  AGO2; PYCARD; chaperone-mediate autophagy; miRNA maturation; neointima formation
    DOI:  https://doi.org/10.1080/15548627.2023.2277610
  35. Immunity. 2023 Nov 14. pii: S1074-7613(23)00451-X. [Epub ahead of print]56(11): 2555-2569.e5
    Reprogramming tumor-associated macrophages to outcompete endovascular endothelial progenitor cells and suppress tumor neoangiogenesis.
    Mytrang H Do, Wei Shi, Liangliang Ji, Erik Ladewig, Xian Zhang, Raghvendra M Srivastava, Kristelle J Capistrano, Chaucie Edwards, Isha Malik, Briana G Nixon, Efstathios G Stamatiades, Ming Liu, Shun Li, Peng Li, Chun Chou, Ke Xu, Ting-Wei Hsu, Xinxin Wang, Timothy A Chan, Christina S Leslie, Ming O Li.
      Tumors develop by invoking a supportive environment characterized by aberrant angiogenesis and infiltration of tumor-associated macrophages (TAMs). In a transgenic model of breast cancer, we found that TAMs localized to the tumor parenchyma and were smaller than mammary tissue macrophages. TAMs had low activity of the metabolic regulator mammalian/mechanistic target of rapamycin complex 1 (mTORC1), and depletion of negative regulator of mTORC1 signaling, tuberous sclerosis complex 1 (TSC1), in TAMs inhibited tumor growth in a manner independent of adaptive lymphocytes. Whereas wild-type TAMs exhibited inflammatory and angiogenic gene expression profiles, TSC1-deficient TAMs had a pro-resolving phenotype. TSC1-deficient TAMs relocated to a perivascular niche, depleted protein C receptor (PROCR)-expressing endovascular endothelial progenitor cells, and rectified the hyperpermeable blood vasculature, causing tumor tissue hypoxia and cancer cell death. TSC1-deficient TAMs were metabolically active and effectively eliminated PROCR-expressing endothelial cells in cell competition experiments. Thus, TAMs exhibit a TSC1-dependent mTORC1-low state, and increasing mTORC1 signaling promotes a pro-resolving state that suppresses tumor growth, defining an innate immune tumor suppression pathway that may be exploited for cancer immunotherapy.
    Keywords:  TSC; cell competition; endothelial progenitor cell; mTORC1; tumor-associated macrophage
    DOI:  https://doi.org/10.1016/j.immuni.2023.10.010
  36. Ultrastruct Pathol. 2023 Nov 12. 1-11
    The Sonic hedgehog pathway inhibitor GDC0449 induces autophagic death in human Medulloblastoma Daoy cells.
    Qi Zhang, Wanjing Zou, Longtao He, Cuiping Zhang, Ying Wang.
      Medulloblastoma (MB) is a frequently occurring malignant brain tumor in children, and many of these tumors are identified by the abnormal activation of the Sonic Hedgehog (SHH) pathway. Although the Shh inhibitor GDC0449 initially shows some effectiveness in certain tumors, they eventually recur due to drug resistance mechanisms, highlighting the need for new treatment options. In this study, we explore whether GDC0449 induces autophagy in the human MB cell lines. To investigate the ultrastructural pathology changes of GDC0449-treated Daoy and D283 cells, we employed Transmission Electron Microscopy (TEM) technology to identify the expression of autophagic vacuoles. Our results indicate that GDC0449 only increases autophagy in Daoy cells by increasing the LC3-II/LC3-I ratio and autophagosome formation.We also analyzed Beclin1, LC3, Bax, and Cleaved-caspase3 protein and mRNA expression levels of autophagic and apoptotic markers using fluorescence confocal microscopy, RT-PCR, and Western blot. We found that cell autophagy and apoptosis increased in a dose-dependent manner with GDC0449 treatment. Additionally, we observed increased mammalian target of rapamycin (mTOR) phosphorylation and decreased protein kinase B (AKT/PKB), Ribosomal Protein S6, eIF4E-binding protein (4EBP1) phosphorylation in GDC0449-treated Daoy cells. It was observed that inhibiting autophagy using Beclin1 siRNA significantly blocked the apoptosis-inducing effects of GDC0449, suggesting that GDC0449 mediates its apoptotic effects by inducing autophagy.Our data suggests that GDC0449 inhibits the growth of human MB Daoy cells by autophagy-mediated apoptosis. The mechanism of GDC0449-induced autophagy in Daoy cells may be related to the inhibition of the PI3K/AKT/mTOR signaling pathway.
    Keywords:  Apoptosis; GDC0449; MB; PI3K/Akt/mTOR; autophagy
    DOI:  https://doi.org/10.1080/01913123.2023.2270676
  37. Cell Rep. 2023 Nov 13. pii: S2211-1247(23)01442-0. [Epub ahead of print]42(11): 113430
    Macrophage autophagy deficiency-induced CEBPB accumulation alleviates atopic dermatitis via impairing M2 polarization.
    Yongcheng Zhu, Yunyao Liu, Yuxiang Ma, Liu Chen, He Huang, Siting Huang, Huiling Zhang, Yuying He, Cheng Tan, Yuan He, Lei Qiang.
      Macroautophagy/autophagy plays a pivotal role in immune regulation. Its significance is evident in modulation of immune cell differentiation and maturation, physiologically and pathologically. Here, we investigate the role of macrophage autophagy on the development of atopic dermatitis (AD). By employing an MC903-induced AD mice model, we observe reduced cutaneous inflammation in macrophage Atg5 cKO mice compared with WT mice. Notably, there is a decreased infiltration of M2 macrophages in lesional skin from Atg5 cKO mice. Furthermore, impaired STAT6 phosphorylation and diminished expression of M2 markers are detected in autophagy-deficient macrophages. Our mechanistic exploration reveals that CEBPB drives the transcription of SOCS1/3 and SQSTM1/p62-mediated autophagy degrades CEBPB normally. Autophagy deficiency leads to CEBPB accumulation, and further promotes the expression of SOCS1/3. This process inhibits JAK1-STAT6 pathway activation and M2 marker expression. Together, our study indicates that autophagy is required for M2 activation and macrophage autophagy may be a promising target for AD intervention.
    Keywords:  CEBPB; CP: Immunology; M2 activation; SOCS1 and SOCS3; SQSTM1/p62; atopic dermatitis; autophagy
    DOI:  https://doi.org/10.1016/j.celrep.2023.113430
  38. bioRxiv. 2023 Oct 25. pii: 2023.10.24.563658. [Epub ahead of print]
    Collapse of late endosomal pH elicits a rapid Rab7 response via V-ATPase and RILP.
    R J Mulligan, M M Magaj, S Redemann, C C Yap, B Winckler.
      Endosomal-lysosomal trafficking entails progressive acidification of endosomal compartments by the H + -V-ATPase to reach low lysosomal pH. Disruption of proper pH affects lysosomal function and the balance of protein synthesis and degradation (proteostasis). Disruption of endosomal pH also impairs endocytic maturation upstream of the lysosome. Using a lysosomal damage model (LLOMe), we identify the late endosomal small GTPase Rab7 as a rapid responder to endosomal/lysosomal pH neutralization. Luminal pH neutralization in LLOMe leads to increased assembly of the V 1 G 1 subunit of the V-ATPase on endosomal membranes and stabilization of Rab7 in the GTP-bound form. Rab7 stabilization is driven by a combination of pump assembly and the Rab7 effector RILP, while contributing to loss of late endosome tubulation and recycling of membrane receptors, like CI-M6PR. Our findings suggest a physiological cascade on late endosomes driven by V-ATPase assembly and Rab7 stabilization to counteract pH neutralization, and a novel model of how late endosomes broadly contribute to cellular stress responses, including LLOMe-mediated damage.Summary: Using a lysosomal damage model, Mulligan et al. demonstrates that pH collapse in otherwise undamaged late endosomes leads to V-ATPase- and RILP-mediated hyperactivation of the small GTPase Rab7, disrupting normal late endosome tubulation behavior and biosynthetic receptor trafficking. These findings suggest a pH driven late endosomal stress response.
    DOI:  https://doi.org/10.1101/2023.10.24.563658
  39. Front Cell Dev Biol. 2023 ;11 1238546
    Knockdown of Y-box binding protein 1 induces autophagy in early porcine embryos.
    Wen-Jie Jiang, Song-Hee Lee, Geun Heo, Hak Jae Chung, Eun Seok Cho, Soo Jin Sa, Shinichi Hochi, Xiang-Shun Cui.
      Y-box binding protein 1 (YBX1) plays important roles in RNA stabilization, translation, transcriptional regulation, and mitophagy. However, its effects on porcine preimplantation embryos remain unclear. In this study, we knocked down YBX1 in the one-cell (1C) stage embryo via small interfering RNA microinjection to determine its function in porcine embryo development. The mRNA level of YBX1 was found to be highly expressed at the four-cell (4C) stage in porcine embryos compared with one-cell (1C) and two-cell (2C) stages. The number of blastocysts was reduced following YBX1 knockdown. Notably, YBX1 knockdown decreased the phosphatase and tensin homolog-induced kinase 1 (PINK1) and parkin RBR E3 ubiquitin protein ligase (PRKN) mRNA levels. YBX1 knockdown also decreased PINK1, active mitochondria, and sirtuin 1 levels, indicating reduced mitophagy and mitochondrial biogenesis. Furthermore, YBX1 knockdown increased the levels of glucose-regulated protein 78 (GRP78) and calnexin, leading to endoplasmic reticulum (ER) stress. Additionally, YBX1 knockdown increased autophagy and apoptosis. In conclusion, knockdown of YBX1 decreases mitochondrial function, while increasing ER stress and autophagy during embryonic development.
    Keywords:  YBX1; autophagy; er stress; mitochondria; pig
    DOI:  https://doi.org/10.3389/fcell.2023.1238546
  40. Cell Commun Signal. 2023 Nov 13. 21(1): 326
    CHOP upregulation and dysregulation of the mature form of the SNAT2 amino acid transporter in the placentas from small for gestational age newborns.
    Emma Barroso, Marta Díaz, Ana Cristina Reguera, Mona Peyman, Jesús Balsinde, Javier Jurado-Aguilar, Meijian Zhang, Adel Rostami, Xavier Palomer, Lourdes Ibáñez, Manuel Vázquez-Carrera.
      BACKGROUND: The placentas from newborns that are small for gestational age (SGA; birth weight < -2 SD for gestational age) may display multiple pathological characteristics. A key determinant of fetal growth and, therefore, birth weight is placental amino acid transport, which is under the control of the serine/threonine kinase mechanistic target of rapamycin (mTOR). The effects of endoplasmic reticulum (ER) stress on the mTOR pathway and the levels of amino acid transporters are not well established.METHODS: Placentas from SGA and appropriate for gestational age (AGA) newborns and the human placental BeWo cell line exposed to the ER stressor tunicamycin were used.
    RESULTS: We detected a significant increase in the levels of C/EBP homologous protein (CHOP) in the placentas from SGA newborns compared with those from AGA newborns, while the levels of other ER stress markers were barely affected. In addition, placental mTOR Complex 1 (mTORC1) activity and the levels of the mature form of the amino acid transporter sodium-coupled neutral amino acid transporter 2 (SNAT2) were also reduced in the SGA group. Interestingly, CHOP has been reported to upregulate growth arrest and DNA damage-inducible protein 34 (GADD34), which in turn suppresses mTORC1 activity. The GADD34 inhibitor guanabenz attenuated the increase in CHOP protein levels and the reduction in mTORC1 activity caused by the ER stressor tunicamycin in the human placental cell line BeWo, but it did not recover mature SNAT2 protein levels, which might be reduced as a result of defective glycosylation.
    CONCLUSIONS: Collectively, these data reveal that GADD34A activity and glycosylation are key factors controlling mTORC1 signaling and mature SNAT2 levels in trophoblasts, respectively, and might contribute to the SGA condition. Video Abstract.
    Keywords:  CHOP; ER stress; GADD34; Placenta; SNAT2; mTORC1
    DOI:  https://doi.org/10.1186/s12964-023-01352-5
  41. Dis Model Mech. 2023 Nov 16. pii: dmm.050223. [Epub ahead of print]
    APOL1-G2 accelerates nephrocyte cell death by inhibiting the autophagy pathway.
    Jun-Yi Zhu, Jin-Gu Lee, Yulong Fu, Joyce van de Leemput, Patricio E Ray, Zhe Han.
      People of African ancestry carrying the APOL1 risk alleles (RA) G1 or G2 are at high risk of developing kidney diseases through not fully understood mechanisms that impair the function of podocytes. It is also not clear whether the APOL1-G1 and G2 RA affect these cells through similar mechanisms. Previously, we developed transgenic Drosophila fly lines expressing either the human APOL1 reference allele (G0) or APOL1-G1 specifically in nephrocytes, the cells homologous to mammalian podocytes. We found that nephrocytes that expressed the APOL1-G1 RA displayed accelerated cell death, in a manner similar to cultured human podocytes and APOL1 transgenic mouse models. Here, to compare how the APOL1-G1 and G2 RA affect the structure and function of nephrocytes in vivo, we generated nephrocyte-specific transgenic flies that expressed the APOL1-G2 or G1G2 RA (on the same allele). We found that G2 and G1G2-expressing nephrocytes developed more severe changes in autophagic pathways, acidification of organelles, and the structure of the slit diaphragms, compared to G1 nephrocytes, leading to their premature death. We conclude that both RA affect similar key cell trafficking pathways, leading to reduced autophagy, and suggesting new therapeutic targets to prevent APOL1-kidney diseases.
    Keywords:   Drosophila ; APOL1; Autophagy; Endocytosis; Nephrocyte; Podocyte
    DOI:  https://doi.org/10.1242/dmm.050223
  42. J Dairy Sci. 2023 Nov 15. pii: S0022-0302(23)00809-3. [Epub ahead of print]
    Evaluation of hepatic AMP-activated protein kinase (AMPK), mechanistic target of rapamycin kinase complex 1 (mTORC1) and autophagy-lysosomal pathway in cows with mild or moderate fatty liver.
    Xiliang Du, Meng Chen, Zhiyuan Fang, Qi Shao, Hao Yu, Xue Hao, Xinxing Gao, Lingxue Jv, Chenxu Li, Yuting Yang, Yuxiang Song, Lin Lei, Guowen Liu, Xinwei Li.
      The aim of the present study was to investigate the activity of AMP-activated protein kinase (AMPK) and mechanistic target of rapamycin kinase complex 1 (mTORC1) as well as transcription factor EB (TFEB) transcriptional activity and autophagy-lysosomal function in the liver of dairy cows with mild fatty liver (FL) and cows with moderate FL. Liver and blood samples were collected from healthy dairy cows (n = 10; hepatic triglyceride content < 1% wet weight) and cows with mild FL (n = 10; 1% ≤ hepatic triglyceride content < 5% wet weight) or moderate FL (n = 10; 5% ≤ hepatic triglyceride content < 10% wet weight) that had a similar number of lactations (median = 3, range = 2 to 4) and DIM (median = 6 d, range = 3 to 9). Blood parameters were determined using a Hitachi 3130 autoanalyzer with commercially-available kits. Protein and mRNA abundance was determined using Western blotting and quantitative real-time PCR, respectively. Activity of calcineurin and β-N-Acetylglucosaminidase was measured with commercial assay kits. Data were analyzed using one-way ANOVA with subsequent Bonferroni correction. Blood concentrations of glucose were lower in moderate FL cows (3.03 ± 0.21 mM) than in healthy (3.71 ± 0.14 mM) and mild FL cows (3.76 ± 0.14 mM). Blood concentrations of β-hydroxybutyrate (BHB, 1.37 ± 0.15 mM in mild FL, 1.88 ± 0.17 mM in moderate FL) and free fatty acids (FFA, 0.69 ± 0.05 mM in mild FL, 0.96 ± 0.09 mM in moderate FL) were greater in FL cows than in healthy cows (BHB, 0.76 ± 0.12 mM; FFA, 0.42 ± 0.04 mM). Compared with healthy cows, phosphorylation of AMPK and its downstream target acetyl-CoA carboxylase 1 was greater and lower in cows with mild and moderate FL, respectively. Phosphorylation of mTOR was lower in cows with mild FL compared with healthy cows. In cows with moderate FL, phosphorylation of mTOR and its downstream effectors was greater than in healthy cows and cows with mild FL. The mRNA abundance of TFEB was downregulated in cows with moderate FL compared with healthy cows and mild FL cows. In mild FL cows, the mRNA and protein abundance of TFEB was greater than in healthy cows. Compared with healthy cows, the mRNA abundance of autophagy markers sequestosome-1 and microtubule-associated protein 1 light chain 3-II, the protein and mRNA abundance of lysosome-associated membrane protein 1 and cathepsin D were increased in mild FL cows, but decreased in moderate FL cows. Compared with healthy cows, the mRNA abundance of mucolipin 1 and activities of β-N-acetylglucosaminidase and calcineurin were higher in cows with mild FL, but lower in cows with moderate FL. These data demonstrate that hepatic AMPK signaling pathway, TFEB transcriptional activity and autophagy-lysosomal function are increased in dairy cows with mild FL, hepatic mTORC1 signaling pathway is inhibited in mild FL cows but activated in moderate FL cows, and activities of AMPK and TFEB as well as autophagy-lysosomal function are impaired in moderate FL cows.
    Keywords:  TFEB; autophagy; energy metabolism; fatty liver
    DOI:  https://doi.org/10.3168/jds.2023-24000
  43. Int Immunopharmacol. 2023 Nov 09. pii: S1567-5769(23)01498-4. [Epub ahead of print]125(Pt B): 111172
    RapaLink-1 outperforms rapamycin in alleviating allogeneic graft rejection by inhibiting the mTORC1-4E-BP1 pathway in mice.
    Ning Wang, Ke Zhou, Zhi Liang, Ruiqi Sun, Hong Tang, Zhentao Yang, Wentao Zhao, Yiyang Peng, Penghong Song, Shusen Zheng, Haiyang Xie.
      Inhibition of mammalian target of rapamycin (mTOR), which is a component of both mTORC1 and mTORC2, leads to clinical benefits for organ transplant recipients. Pathways to inhibit mTOR include strengthening the association of FKBP12-mTOR or competing with ATP at the active site of mTOR, which have been applied to the design of first- and second-generation mTOR inhibitors, respectively. However, the clinical efficacy of these mTOR inhibitors may be limited by side effects, compensatory activation of kinases and attenuation of feedback inhibition of receptor expression. A new generation of mTOR inhibitors possess a core structure similar to rapamycin and covalently link to mTOR kinase inhibitors, resulting in moderate selectivity and potent inhibition of mTORC1. Since the immunosuppressive potential of this class of compounds remains unknown, our goal is to examine the therapeutic efficacy of a third-generation mTOR inhibitor in organ transplantation. In this study, RapaLink-1 outperformed rapamycin in inhibiting T-cell proliferation and significantly prolonged graft survival time. Mechanistically, the ameliorated rejection induced by RapaLink-1 is associated with a reduction in p-4E-BP1 in T cells, resulting in an elevation in Treg cells alongside a decline in Th1 and Th17 cells. For the first time, these studies demonstrate the effectiveness of third-generation mTOR inhibitors in inhibiting allograft rejection, highlighting the potential of this novel class of mTOR inhibitors for further investigation.
    Keywords:  Allogeneic graft rejection; Immunosuppression; RapaLink-1; Rapamycin; mTOR; p-4E-BP1
    DOI:  https://doi.org/10.1016/j.intimp.2023.111172
  44. Nutrients. 2023 Oct 27. pii: 4574. [Epub ahead of print]15(21):
    Intermittent Fasting Attenuates Metabolic-Dysfunction-Associated Steatohepatitis by Enhancing the Hepatic Autophagy-Lysosome Pathway.
    Kyung Eun Kim, Hyun Joo Shin, Yeajin Ju, Youngae Jung, Hyeong Seok An, So Jeong Lee, Eun Ae Jeong, Jaewoong Lee, Geum-Sook Hwang, Gu Seob Roh.
      An intermittent fasting (IF) regimen has been shown to protect against metabolic dysfunction-associated steatohepatitis (MASH). However, the precise mechanism remains unclear. Here, we explored how IF reduced hepatic lipid accumulation, inflammation, and fibrosis in mice with MASH. The mice were fed a high-fat diet (HFD) for 30 weeks and either continued on the HFD or were subjected to IF for the final 22 weeks. IF reduced body weight, insulin resistance, and hepatic lipid accumulation in HFD-fed mice. Lipidome analysis revealed that IF modified HFD-induced hepatic lipid composition. In particular, HFD-induced impaired autophagic flux was reversed by IF. The decreased hepatic lysosome-associated membrane protein 1 level in HFD-fed mice was upregulated in HFD+IF-fed mice. However, increased hepatic lysosomal acid lipase protein levels in HFD-fed mice were reduced by IF. IF attenuated HFD-induced hepatic inflammation and galectin-3-positive Kupffer cells. In addition to the increases in hepatic hydroxyproline and lumican levels, lipocalin-2-mediated signaling was reversed in HFD-fed mice by IF. Taken together, our findings indicate that the enhancement of the autophagy-lysosomal pathway may be a critical mechanism of MASH reduction by IF.
    Keywords:  autophagy; intermittent fasting; lysosome; non-alcoholic steatohepatitis
    DOI:  https://doi.org/10.3390/nu15214574
  45. Autophagy. 2023 Nov 18. 1-22
    Autophagy activates EGR1 via MAPK/ERK to induce FGF2 in renal tubular cells for fibroblast activation and fibrosis during maladaptive kidney repair.
    Man J Livingston, Ming Zhang, Sang-Ho Kwon, Jian-Kang Chen, Honglin Li, Santhakumar Manicassamy, Zheng Dong.
      Macroautophagy/autophagy contributes to maladaptive kidney repair by inducing pro-fibrotic factors such as FGF2 (fibroblast growth factor 2), but the underlying mechanism remains elusive. Here, we show that EGR1 (early growth response 1) was induced in injured proximal tubules after ischemic acute kidney injury (AKI) and this induction was suppressed by autophagy deficiency in inducible, renal tubule-specific atg7 (autophagy related 7) knockout (iRT-atg7 KO) mice. In cultured proximal tubular cells, TGFB1 (transforming growth factor beta 1) induced EGR1 and this induction was also autophagy dependent. Egr1 knockdown in tubular cells reduced FGF2 expression during TGFB1 treatment, leading to less FGF2 secretion and decreased paracrine effects on fibroblasts. ChIP assay detected an increased binding of EGR1 to the Fgf2 gene promoter in TGFB1-treated tubular cells. Both Fgf2 and Egr1 transcription was inhibited by FGF2 neutralizing antibody, suggesting a positive feedback for EGR1-mediated FGF2 autoregulation. This feedback was confirmed using fgf2-deficient tubular cells and fgf2-deficient mice. Upstream of EGR1, autophagy deficiency in mice suppressed MAPK/ERK (mitogen-activated protein kinase) activation in post-ischemic renal tubules. This inhibition correlated with SQSTM1/p62 (sequestosome 1) aggregation and its sequestration of MAPK/ERK. SQSTM1/p62 interacted with MAPK/ERK and blocked its activation during TGFB1 treatment in autophagy-deficient tubular cells. Inhibition of MAPK/ERK suppressed EGR1 and FGF2 expression in maladaptive tubules, leading to the amelioration of renal fibrosis and improvement of renal function. These results suggest that autophagy activates MAPK/ERK in renal tubular cells, which induces EGR1 to transactivate FGF2. FGF2 is then secreted into the interstitium to stimulate fibroblasts for fibrogenesis.Abbreviation: 3-MA: 3-methyladenine; ACTA2/α-SMA: actin alpha 2, smooth muscle, aorta; ACTB/β-actin: actin, beta; AKI: acute kidney injury; aa: amino acid; ATG/Atg: autophagy related; BUN: blood urea nitrogen; ChIP: chromatin immunoprecipitation; CKD: chronic kidney disease; CM: conditioned medium; COL1A1: collagen, type I, alpha 1; COL4A1: collagen, type IV, alpha 1; CQ: chloroquine; DBA: dolichos biflorus agglutinin; EGR1: early growth response 1; ELK1: ELK1, member of ETS oncogene family; FGF2: fibroblast growth factor 2; FN1: fibronectin 1; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; HAVCR1/KIM-1: hepatitis A virus cellular receptor 1; IP: immunoprecipitation; LIR: LC3-interacting region; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MAP2K/MEK: mitogen-activated protein kinase kinase; MAPK: mitogen-activated protein kinase; NFKB: nuclear factor kappa B; PB1: Phox and Bem1; PFT: pifithrin α; PPIB/cyclophilin B: peptidylprolyl isomerase B; RT-qPCR: real time-quantitative PCR; SQSTM1/p62: sequestosome 1; TGFB1/TGF-β1: transforming growth factor beta 1; VIM: vimentin.
    Keywords:  Interstitial fibrosis; SQSTM1/p62; ischemic acute kidney injury; kidney repair; tubulo-interstitial communication
    DOI:  https://doi.org/10.1080/15548627.2023.2281156
  46. J Agric Food Chem. 2023 Nov 13.
    Current Advances in the Regulatory Effects of Bioactive Compounds from Dietary Resources on Nonalcoholic Fatty Liver Disease: Role of Autophagy.
    Yue Zhang, Qing Chen, Xiong Fu, Siming Zhu, Qiang Huang, Chao Li.
      Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease characterized by lipid metabolic disorder primarily due to sedentary lifestyles and excessive food consumption. However, there are currently no approved and effective drugs available to treat NAFLD. In recent years, research has shown that dietary bioactive compounds, such as polysaccharides, polyphenols, flavones, and alkaloids, have the potential to improve NAFLD by regulating autophagy. However, there is no up-to-date review of research progress in this field. This review aims to systematically summarize and discuss the regulatory effects and molecular mechanisms of dietary bioactive compounds on NAFLD through the modulation of autophagy. The existing research has demonstrated that some dietary bioactive compounds can effectively improve various aspects of NAFLD progression, such as lipid metabolism, insulin resistance (IR), endoplasmic reticulum (ER) stress, oxidative stress, mitochondrial homeostasis, and inflammation. Molecular mechanism studies have revealed that they exert their beneficial effects on NAFLD through autophagy-mediated signaling pathways, predominantly involving transcription factor EB (TFEB), mammalian target of rapamycin (mTOR), adenosine monophosphate-activated protein kinase (AMPK), peroxisome proliferator-activated receptors (PPARs), SIRT, and PTEN-induced kinase 1 (PINK1)/parkin. Furthermore, the challenges and prospects of current research in this field are highlighted. Overall, this review provides valuable insights into the potential treatment of NAFLD using dietary bioactive compounds that can modulate autophagy.
    Keywords:  autophagy; bioactive compounds; inflammation; lipid metabolism
    DOI:  https://doi.org/10.1021/acs.jafc.3c04692
  47. Biol Reprod. 2023 Nov 17. pii: ioad160. [Epub ahead of print]
    Autophagy core protein BECN1 is vital for spermatogenesis and male fertility in mice.
    Lu Ke, Xinyi Lin, Yuchuan Luo, Siming Tao, Chang Yan, Yifeilong He, Yingjie Wu, Ning Liu, Yinghe Qin.
      Mammalian spermatogenesis is a highly complex multi-step biological process, and autophagy has been demonstrated to be involved in the process of spermatogenesis. Beclin-1/BECN1, a core autophagy factor, plays a critical role in many biological processes and diseases. However, its function in spermatogenesis remains largely unclear. In the present study, germ cell-specific Beclin 1 (Becn1) knockout mice were generated and were conducted to determine the role of Becn1 in spermatogenesis and fertility of mice. Results indicate that Becn1 deficiency leads to reduced sperm motility and quantity, partial failure of spermiation, actin network disruption, excessive residual cytoplasm, acrosome malformation, aberrant mitochondrial accumulation of sperm, ultimately resulting in reduced fertility in male mice. Furthermore, inhibition of autophagy was observed in the testes of germ cell-specific Becn1 knockout mice, which may contribute to impaired spermiogenesis and reduced fertility. Collectively, our results reveal that Becn1 is essential for fertility and spermiogenesis in mice.
    Keywords:  BECN1; acrosome; autophagy; mitochondria; spermiogenesis
    DOI:  https://doi.org/10.1093/biolre/ioad160
  48. bioRxiv. 2023 Oct 27. pii: 2023.10.27.564195. [Epub ahead of print]
    ATR promotes mTORC1 activation via de novo cholesterol synthesis in p16-low cancer cells.
    Naveen Kumar Tangudu, Zhentai Huang, Richard Fang, Raquel Buj, Apoorva Uboveja, Aidan R Cole, Cassandra Happe, Mai Sun, Stacy L Gelhaus, Matthew L MacDonald, Nadine Hempel, Nathaniel W Snyder, Katherine M Aird.
      DNA damage and cellular metabolism are intricately linked with bidirectional feedback. Two of the main effectors of the DNA damage response and control of cellular metabolism are ATR and mTORC1, respectively. Prior work has placed ATR upstream of mTORC1 during replication stress, yet the direct mechanism for how mTORC1 is activated in this context remain unclear. We previously published that p16-low cells have mTORC1 hyperactivation, which in part promotes their proliferation. Using this model, we found that ATR, but not ATM, is upstream of mTORC1 activation via de novo cholesterol synthesis and is associated with increased lanosterol synthase (LSS). Indeed, p16-low cells showed increased cholesterol abundance. Additionally, knockdown of either ATR or LSS decreased mTORC1 activity. Decreased mTORC1 activity due to ATR knockdown was rescued by cholesterol supplementation. Finally, using both LSS inhibitors and multiple FDA-approved de novo cholesterol synthesis inhibitors, we found that the de novo cholesterol biosynthesis pathway is a metabolic vulnerability of p16-low cells. Together, our data provide new evidence coupling the DNA damage response and cholesterol metabolism and demonstrate the feasibility of using FDA-approved cholesterol-lowering drugs in tumors with loss of p16.
    DOI:  https://doi.org/10.1101/2023.10.27.564195
  49. Mol Cell. 2023 Nov 16. pii: S1097-2765(23)00854-7. [Epub ahead of print]83(22): 4078-4092.e6
    Active growth signaling promotes senescence and cancer cell sensitivity to CDK7 inhibition.
    Gemma A Wilson, Karla Vuina, Georgina Sava, Caroline Huard, Leticia Meneguello, Jasmin Coulombe-Huntington, Thierry Bertomeu, Rory J Maizels, Josh Lauring, Janos Kriston-Vizi, Mike Tyers, Simak Ali, Cosetta Bertoli, Robertus A M de Bruin.
      Tumor growth is driven by continued cellular growth and proliferation. Cyclin-dependent kinase 7's (CDK7) role in activating mitotic CDKs and global gene expression makes it therefore an attractive target for cancer therapies. However, what makes cancer cells particularly sensitive to CDK7 inhibition (CDK7i) remains unclear. Here, we address this question. We show that CDK7i, by samuraciclib, induces a permanent cell-cycle exit, known as senescence, without promoting DNA damage signaling or cell death. A chemogenetic genome-wide CRISPR knockout screen identified that active mTOR (mammalian target of rapamycin) signaling promotes samuraciclib-induced senescence. mTOR inhibition decreases samuraciclib sensitivity, and increased mTOR-dependent growth signaling correlates with sensitivity in cancer cell lines. Reverting a growth-promoting mutation in PIK3CA to wild type decreases sensitivity to CDK7i. Our work establishes that enhanced growth alone promotes CDK7i sensitivity, providing an explanation for why some cancers are more sensitive to CDK inhibition than normally growing cells.
    Keywords:  CDK inhibition; CDK7 inhibitor; cancer treatment; cell cycle; cell size; cell-cycle arrest; cellular growth; mTOR singaling; proliferation; samuraciclib; senescence
    DOI:  https://doi.org/10.1016/j.molcel.2023.10.017
  50. iScience. 2023 Oct 20. 26(10): 107752
    The PtdIns3P phosphatase MtMP promotes symbiotic nitrogen fixation via mitophagy in Medicago truncatula.
    Qixia Xue, Chen Shen, Qianwen Liu, Peng Liu, Da Guo, Lihua Zheng, Jinling Liu, Chang Liu, Qinyi Ye, Tao Wang, Jiangli Dong.
      Symbiotic nitrogen fixation is a complex process in which legumes interact with rhizobia under nitrogen starvation. In this study, we found that myotubularin phosphatase (MtMP) is mainly expressed in roots and nodules in Medicago truncatula. MtMP promotes autophagy by dephosphorylating PtdIns3P on autophagosomes. The mp mutants inoculated with rhizobia showed a significant reduction in nitrogenase activity and significantly higher number of mitochondria than those of wild-type plants under nitrogen starvation, indicating that MtMP is involved in mitophagy of the infection zone. Mitophagy may provide carbon skeletons and nitrogen for the development of bacteroids and the reprogramming of infected cells. In conclusion, we found, for the first time, that myotubularin phosphatase is involved in autophagy in plants. MtMP-involved autophagy plays an active role in symbiotic nitrogen fixation. These results deepen our understanding of symbiotic nitrogen fixation.
    Keywords:  Cell biology; Interaction of plants with organisms; Molecular biology
    DOI:  https://doi.org/10.1016/j.isci.2023.107752
  51. Cell Mol Life Sci. 2023 Nov 11. 80(12): 358
    TFEB SUMOylation in macrophages accelerates atherosclerosis by promoting the formation of foam cells through inhibiting lysosomal activity.
    Kezhou Wang, Wei Zhou, Gaolei Hu, Lifeng Wang, Rong Cai, Tian Tian.
      Atherosclerosis (AS) is a serious cardiovascular disease. One of its hallmarks is hyperlipidemia. Inhibiting the formation of macrophage foam cells is critical for alleviating AS. Transcription factor EB (TFEB) can limit the formation of macrophage foam cells by upregulating lysosomal activity. We examined whether TFEB SUMOylation is involved in this progress during AS. In this study, we investigated the role of TFEB SUMOylation in macrophages in AS using TFEB SUMOylation deficiency Ldlr-/- (TFEB-KR: Ldlr-/-) transgenic mice and TFEB-KR bone marrow-derived macrophages. We observed that TFEB-KR: Ldlr-/- atherosclerotic mice had thinner plaques and macrophages with higher lysosomal activity when compared to WT: Ldlr-/- mice. TFEB SUMOylation in macrophages decreased after oxidized low-density lipoprotein (OxLDL) treatment in vitro. Compared with wild type macrophages, TFEB-KR macrophages exhibited less lipid deposition after OxLDL treatment. Our study demonstrated that in AS, deSUMOylation of TFEB could inhibit the formation of macrophage foam cells through enhancing lysosomal biogenesis and autophagy, further reducing the accumulation of lipids in macrophages, and ultimately alleviating the development of AS. Thus, TFEB SUMOylation can be a switch to modulate macrophage foam cells formation and used as a potential target for AS therapy.
    Keywords:  Atherosclerosis; Macrophage foam cells; SUMOylation; TFEB
    DOI:  https://doi.org/10.1007/s00018-023-04981-8
  52. Mol Cell Endocrinol. 2023 Nov 11. pii: S0303-7207(23)00260-5. [Epub ahead of print] 112109
    Activation of mitophagy improves cognitive dysfunction in diabetic mice with recurrent non-severe hypoglycemia.
    Kejun Wu, Cuihua Huang, Wenrong Zheng, Yubin Wu, Qintao Huang, Menghua Lin, Ruonan Gao, Liqin Qi, Guanlian He, Xiaoying Liu, Xiaohong Liu, Linxi Wang, Zhou Chen, Libin Liu.
      Recurrent non-severe hypoglycemia (RH) in patients with diabetes might be associated with cognitive impairment. Previously, we found that mitochondrial dysfunction plays an important role in this pathological process; however, the mechanism remains unclear. The objective of this study was to determine the molecular mechanisms of mitochondrial damage associated with RH in diabetes mellitus (DM). We found that RH is associated with reduced hippocampal mitophagy in diabetic mice, mainly manifested by reduced autophagosome formation and impaired recognition of impaired mitochondria, mediated by the PINK1/Parkin pathway. The same impaired mitophagy initiation was observed in an in vitro high-glucose cultured astrocyte model with recurrent low-glucose interventions. Promoting autophagosome formation and activating PINK1/Parkin-mediated mitophagy protected mitochondrial function and cognitive function in mice. The results showed that impaired mitophagy is involved in the occurrence of mitochondrial dysfunction, mediating the neurological impairment associated with recurrent low glucose under high glucose conditions.
    Keywords:  Astrocyte; Cognitive impairment; Diabetes; Mitophagy; Recurrent non-severe hypoglycemia
    DOI:  https://doi.org/10.1016/j.mce.2023.112109
  53. J Neuropathol Exp Neurol. 2023 Nov 14. pii: nlad091. [Epub ahead of print]
    METTL3-mediated maturation of miR-192-5p targets ATG7 to prevent Schwann cell autophagy in peripheral nerve injury.
    Xing Liu, Jun Lv, Weilong Tang, Yuanbai Hu, Yiwei Wen, Hongtao Shen.
      The inhibition of miR-192-5p can promote nerve repair in rats with peripheral nerve injury (PNI) but the precise mechanisms underlying this effect remain unclear. Schwann cell (SC) autophagy mediated by autophagy-related gene (ATG) proteins has a key role in PNI but it is uncertain whether miR-192-5p affects the involvement of SC autophagy in PNI. In this study, we investigated the impact of methyltransferase-like protein 3 (METTL3)/miR-192-5p/ATG7 on SC autophagy in a rat PNI model and in an SC oxygen and glucose deprivation model. The results revealed that METTL3 stimulated miR-192-5p maturation via m6A methylation to depress ATG7 and SC autophagy and aggravate PNI. These findings provide a new target and potential basis for the treatment of patients with PNI.
    Keywords:  Autophagy; Autophagy-related gene 7; Methyltransferase-like 3; Peripheral nerve injury; Schwann cells; microRNA-192-5p
    DOI:  https://doi.org/10.1093/jnen/nlad091
  54. Sci Adv. 2023 Nov 15. 9(46): eadf4345
    Iron deficiency-induced ferritinophagy impairs skeletal muscle regeneration through RNF20-mediated H2Bub1 modification.
    Yunshu Che, Jinteng Li, Peng Wang, Wenhui Yu, Jiajie Lin, Zepeng Su, Feng Ye, Zhaoqiang Zhang, Peitao Xu, Zhongyu Xie, Yanfeng Wu, Huiyong Shen.
      Iron deficiency (ID) is a widespread condition concomitant with disease and results in systemic dysfunction of target tissues including skeletal muscle. Activated by ID, ferritinophagy is a recently found type of selective autophagy, which plays an important role in various physiological and pathological conditions. In this study, we demonstrated that ID-mediated ferritinophagy impeded myogenic differentiation. Mechanistically, ferritinophagy induced RNF20 degradation through the autophagy-lysosomal pathway and then negatively regulated histone H2B monoubiquitination at lysine-120 in the promoters of the myogenic markers MyoD and MyoG, which inhibited myogenic differentiation and regeneration. Conditional knockout of NCOA4 in satellite cells, overexpression of RNF20 or treatment with 3-methyladenine restored skeletal muscle regenerative potential under ID conditions. In patients with ID, RNF20 and H2Bub1 protein expression is downregulated in skeletal muscle. In conclusion, our study indicated that the ferritinophagy-RNF20-H2Bub1 axis is a pathological molecular mechanism underlying ID-induced skeletal muscle impairment, suggesting potential therapeutic prospects.
    DOI:  https://doi.org/10.1126/sciadv.adf4345
  55. Int J Mol Sci. 2023 Nov 02. pii: 15919. [Epub ahead of print]24(21):
    PHB2 Alleviates Neurotoxicity of Prion Peptide PrP106-126 via PINK1/Parkin-Dependent Mitophagy.
    Xiaohui Zheng, Kun Liu, Qingqing Xie, Hangkuo Xin, Wei Chen, Shengyu Lin, Danqi Feng, Ting Zhu.
      Prion diseases are a group of neurodegenerative diseases characterized by mitochondrial dysfunction and neuronal death. Mitophagy is a selective form of macroautophagy that clears injured mitochondria. Prohibitin 2 (PHB2) has been identified as a novel inner membrane mitophagy receptor that mediates mitophagy. However, the role of PHB2 in prion diseases remains unclear. In this study, we isolated primary cortical neurons from rats and used the neurotoxic prion peptide PrP106-126 as a cell model for prion diseases. We examined the role of PHB2 in PrP106-126-induced mitophagy using Western blotting and immunofluorescence microscopy and assessed the function of PHB2 in PrP106-126-induced neuronal death using the cell viability assay and the TUNEL assay. The results showed that PrP106-126 induced mitochondrial morphological abnormalities and mitophagy in primary cortical neurons. PHB2 was found to be indispensable for PrP106-126-induced mitophagy and was involved in the accumulation of PINK1 and recruitment of Parkin to mitochondria in primary neurons. Additionally, PHB2 depletion exacerbated neuronal cell death induced by PrP106-126, whereas the overexpression of PHB2 alleviated PrP106-126 neuronal toxicity. Taken together, this study demonstrated that PHB2 is indispensable for PINK1/Parkin-mediated mitophagy in PrP106-126-treated neurons and protects neurons against the neurotoxicity of the prion peptide.
    Keywords:  PHB2; PINK1/Parkin; PrP106–126; mitophagy; neuronal death; prion disease; prion peptide
    DOI:  https://doi.org/10.3390/ijms242115919
  56. Sci Rep. 2023 Nov 16. 13(1): 20010
    Efficient protocol for the differentiation of kidney podocytes from induced pluripotent stem cells, involving the inhibition of mTOR.
    Masahiro Yasuda, Tadashi Kato, Mai Okano, Hiromi Yamashita, Yoshikazu Matsuoka, Yasumasa Shirouzu, Tatsuya Fujioka, Fumiyuki Hattori, Shoji Tsuji, Kazunari Kaneko, Hirofumi Hitomi.
      The mechanistic/mammalian target of rapamycin (mTOR) is involved in a wide range of cellular processes. However, the role of mTOR in podocytes remains unclear. In this study, we aimed to clarify the role of mTOR in podocyte differentiation from human induced pluripotent stem cells (hiPSCs) and to establish an efficient differentiation protocol for human podocytes. We generated podocytes from hiPSCs by modifying protocol. The expression of the podocyte-specific slit membrane components nephrin and podocin was measured using PCR, western blotting, flow cytometry, and immunostaining; and the role of mTOR was evaluated using inhibitors of the mTOR pathway. Nephrin and podocin were found to be expressed in cells differentiated from hiPSCs, and their expression was increased by mTOR inhibitor treatment. S6, a downstream component of the mTOR pathway, was also found to be involved in podocyte differentiation. we evaluated its permeability to albumin, urea, and electrolytes. The induced podocytes were permeable to the small molecules, but only poorly permeable to albumin. We have shown that the mTOR pathway is involved in podocyte differentiation. Our monolayer podocyte differential protocol, using an mTOR inhibitor, provides a novel in vitro model for studies of kidney physiology and pathology.
    DOI:  https://doi.org/10.1038/s41598-023-47087-8
  57. Eur J Pharmacol. 2023 Nov 14. pii: S0014-2999(23)00712-4. [Epub ahead of print] 176198
    Inhibition of excessive autophagy alleviates renal injury and inflammation in a rat model of immunoglobulin A nephropathy.
    Meiying Chang, Xiujie Shi, Sijia Ma, Mingming Zhao, Jiao Fan, Zhiyu Pan, Shunxuan Xue, Ziyan Zhang, Zhenwei Shi, Bin Yang, Yu Zhang.
      The pathogenesis of immunoglobulin A nephropathy (IgAN) is closely related to immunity and inflammation. The clinical process of IgAN varies greatly, making the assessment of prognosis challenging and limiting progress on effective treatment measures. Autophagy is an important pathway for the development of IgAN. However, the role of autophagy in IgAN is complex, and the consequences of autophagy may change during disease progression. In the present study, we evaluated the dynamic changes in autophagy during IgAN. Specifically, we examined autophagy in the kidney of a rat model of IgAN at different time points. We found that autophagy was markedly and persistently induced in IgAN rats, and the expression level of inflammation was also persistently elevated. The autophagy enhancer rapamycin and autophagy inhibitor 3-methyladenine were used in this study, and the results showed that 3-methyladenine can alleviate renal injury and inflammation in IgAN rats. Our study provides further evidence for autophagy as a therapeutic target for IgAN.
    Keywords:  3-Methyladenine; Autophagy; Immunoglobulin A nephropathy; Inflammation; Renal injury
    DOI:  https://doi.org/10.1016/j.ejphar.2023.176198
  58. J Lipid Res. 2023 Nov 14. pii: S0022-2275(23)00149-9. [Epub ahead of print] 100476
    Lipid structure matters in lysosomal storage disease.
    Roger Sandhoff.
      
    DOI:  https://doi.org/10.1016/j.jlr.2023.100476
  59. Chem Biol Interact. 2023 Nov 10. pii: S0009-2797(23)00461-1. [Epub ahead of print]387 110794
    Targeting PKD2 aggravates ferritinophagy-mediated ferroptosis via promoting autophagosome-lysosome fusion and enhances efficacy of carboplatin in lung adenocarcinoma.
    Yong Liu, Zhaofei Pang, Yadong Wang, Jichang Liu, Guanghui Wang, Jiajun Du.
      Ferroptosis is an iron-dependent cell death and affects efficacies of multiple antitumor regimens, showing a great potential in cancer therapy. Protein kinase D2 (PKD2) plays a crucial role in regulating necrosis and apoptosis. However, the relationship of PKD2 and ferroptosis is still elusive. In this study, we mainly analyzed the roles of PKD2 on ferroptosis and chemotherapy in lung adenocarcinoma (LUAD). We found PKD2 was highly expressed in LUAD and silencing PKD2 could promote erastin-induced reactive oxygen species (ROS), malondialdehyde (MDA) accumulation, intracellular iron content and LUAD cells death. Mechanistically, augmenting PKD2 could prevent autophagic degradation of ferritin, which could be impaired by bafilomycin A1. We further found that PKD2 overexpression would promote LC3B-II, p62/SQSTM1 accumulation and block autophagosome-lysosome fusion in a TFEB-independent manner, which could be impaired by bafilomycin A1. Bafilomycin A1 stimulation could weaken ferroptosis promotion by PKD2 abrogation. Silencing ferritin heavy chain-1 (FTH1) could reverse the resistance to ferroptosis by PKD2 overexpression. Additionally, in vitro and vivo experiments validated PKD2 promoted proliferation, migration and invasion of LUAD cells. PKD2 knockdown or pharmacological inhibition by CRT0066101 could enhance efficacy of carboplatin in LUAD via ferroptosis and apoptosis. Collectively, our study revealed that abrogation of PKD2 could aggravate ferritinophagy-mediated ferroptosis by promoting autophagosome-lysosome fusion and enhance efficacy of carboplatin in LUAD. Targeting PKD2 to induce ferroptosis may be a promising strategy for LUAD therapy.
    Keywords:  Autophagy; Ferroptosis; Lung adenocarcinoma; Protein kinase D2; Reactive oxygen species
    DOI:  https://doi.org/10.1016/j.cbi.2023.110794
  60. Cell Death Dis. 2023 11 11. 14(11): 736
    FKBP5 activates mitophagy by ablating PPAR-γ to shape a benign remyelination environment.
    Xingzong Sun, Menghan Qian, Hongliang Li, Lei Wang, Yunjie Zhao, Min Yin, Lili Dai, Hongkun Bao.
      Multiple sclerosis (MS) is an autoimmune and neurodegenerative disease of the central nervous system (CNS) that is characterized by myelin damage, followed by axonal and ultimately neuronal loss, which has been found to be associated with mitophagy. The etiology and pathology of MS remain elusive. However, the role of FK506 binding protein 5 (FKBP5, also called FKBP51), a newly identified gene associated with MS, in the progression of the disease has not been well defined. Here, we observed that the progress of myelin loss and regeneration in Fkbp5ko mice treated with demyelination for the same amount of time was significantly slower than that in wild-type mice, and that mitophagy plays an important regulatory role in this process. To investigate the mechanism, we discovered that the levels of FKBP5 protein were greatly enhanced in the CNS of cuprizone (CPZ) mice and the myelin-denuded environment stimulates significant activation of the PINK1/Parkin-mediated mitophagy, in which the important regulator, PPAR-γ, is critically regulated by FKBP5. This study reveals the role of FKBP5 in regulating a dynamic pathway of natural restorative regulation of mitophagy through PPAR-γ in pathological demyelinating settings, which may provide potential targets for the treatment of demyelinating diseases.
    DOI:  https://doi.org/10.1038/s41419-023-06260-7
  61. Biochim Biophys Acta Mol Cell Biol Lipids. 2023 Nov 11. pii: S1388-1981(23)00149-X. [Epub ahead of print]1869(1): 159425
    Docosahexaenoic acid (DHA) inhibits abdominal fat accumulation by promoting adipocyte apoptosis through PPARγ-LC3-BNIP3 pathway-mediated mitophagy.
    Chenchen Bian, Xiangtong Yuan, Caihong Zeng, Jian Sun, Gen Kaneko, Hong Ji.
      Obesity has always been an overwhelming health concern worldwide. Docosahexaenoic acid (DHA) reduces abdominal fat accumulation by inducing adipocyte apoptosis, but the underlying mechanism remains unclear. Mitophagy, the process of maintaining mitochondrial homeostasis, has a double-edged sword effect that positively or negatively regulates apoptosis. In this study, grass carp (Ctenopharyngodon idellus) was used as an animal model to investigate the role of mitophagy in regulating apoptosis and the potential molecular mechanisms for DHA-induced mitophagy in vivo and in vitro. Firstly, we found that DHA induced the intrinsic apoptosis in grass carp adipocytes, accompanying by activating BNIP3/NIX-mediated mitophagy. Then, suppression of mitophagy alleviated apoptosis and eliminated the inhibition of lipid accumulation induced by DHA in vivo and in vitro. Mechanistically, the DHA-induced mitophagy was caused by activating PPARγ and its DNA binding capacity to the LC3 promoter, which promoted the interaction of BNIP3 (rather than NIX) with LC3. However, the inhibition of PPARγ in vitro significantly decreased the expression of autophagy-related genes (P < 0.05), reducing the colocalization of mitochondria and lysosomes while preventing BNIP3/NIX-mediated mitophagy-mediated apoptosis and subsequently alleviating the inhibition of lipid accumulation in adipocytes induced by DHA. For the first time, we demonstrated that DHA activates mitophagy by regulating the PPARγ-LC3-BNIP3 pathway, consequently inducing apoptosis, which decreases adipocytes, inhibiting lipid accumulation in grass carp. These findings provide new insight into the mechanism of DHA-induced apoptosis mediated by mitophagy as the potential therapeutic target of inhibiting abdominal fat accumulation in vertebrates.
    Keywords:  Adipocyte; Apoptosis; Docosahexaenoic acid; Grass carp; Lipid accumulation; Mitophagy
    DOI:  https://doi.org/10.1016/j.bbalip.2023.159425
  62. Mol Genet Metab. 2023 Nov 03. pii: S1096-7192(23)00359-1. [Epub ahead of print]140(4): 107729
    New tools can propel research in lysosomal storage diseases.
    Ellen Hertz, Logan M Glasstetter, Yu Chen, Ellen Sidransky.
      Historically, the clinical manifestations of lysosomal storage diseases offered an early glimpse into the essential digestive functions of the lysosome. However, it was only recently that the more subtle role of this organelle in the dynamic regulation of multiple cellular processes was appreciated. With the need for precise interrogation of lysosomal interplay in health and disease comes the demand for more sophisticated functional tools. This demand has recently been met with 1) induced pluripotent stem cell-derived models that recapitulate the disease phenotype in vitro, 2) methods for lysosome affinity purification coupled with downstream omics analysis that provide a high-resolution snapshot of lysosomal alterations, and 3) gene editing and CRISPR/Cas9-based functional genomic strategies that enable screening for genetic modifiers of the disease phenotype. These emerging methods have garnered much interest in the field of neurodegeneration and their use in the field of metabolic disorders is now also steadily gaining momentum. Looking forward, these robust tools should accelerate basic science efforts to understand lysosomal dysfunction distal to substrate accumulation and provide translational opportunities to identify disease-modifying therapies.
    Keywords:  CRISPR; Induced pluripotent stem cells (iPSC); Lyso-IP; Lysosomal storage diseases; Lysosome
    DOI:  https://doi.org/10.1016/j.ymgme.2023.107729
  63. Virulence. 2023 Nov 15. 2283898
    Detoxified pneumolysin derivative ΔA146Ply inhibits triple- negative breast cancer metastasis mainly via mannose receptor-mediated autophagy inhibition.
    Hong Zhang, Tao Zhu, Wenchun Xu, Bichen Liu, Kaifeng Wu, Yibing Yin, Xuemei Zhang.
      The detoxified pneumolysin derivative ΔA146Ply has been proven to have a direct anti-triple negative breast cancer effect by our group, but its work model remains unclear. In this study, we focused on its ability to inhibit triple-negative breast cancer metastasis. We found that ΔA146Ply suppressed the migration and invasion of triple-negative breast cancer cells by activating mannose receptor and toll-like receptor 4. Their activation triggers the activation of the mammalian target of rapamycin signaling, sequentially leading to autophagy, transforming growth factor-β1, and epithelial-mesenchymal transition inhibition. Furthermore, the combination of doxorubicin and ΔA146Ply significantly inhibited triple-negative breast cancer progression and prolonged survival in tumor-bearing mice. Taken together, our study provides an alternative microbiome-based mannose receptor-targeted therapy for triple-negative breast cancer and a novel theoretical and experimental basis for the downstream signaling pathway of the mannose receptor.
    Keywords:  autophagy inhibition; mannose receptor; triple-negative breast cancer; ΔA146Ply
    DOI:  https://doi.org/10.1080/21505594.2023.2283898
  64. J Genet Genomics. 2023 Nov 09. pii: S1673-8527(23)00238-2. [Epub ahead of print]
    Knockdown of neuronal DAF-15/Raptor promotes healthy aging in C. elegans.
    Xiao Zang, Qi Wang, Hanxin Zhang, Yiyan Zhang, Zi Wang, Zixing Wu, Di Chen.
      The highly conserved target of rapamycin (TOR) pathway plays an important role in aging across species. Previous studies have established that inhibition of the TOR complex 1 (TORC1) significantly extends lifespan in C. elegans. However, it has not been clear whether TORC1 perturbation affects aging in a spatiotemporal manner. Here we applied the auxin-inducible degradation (AID) tool to knockdown endogenous DAF-15, the C. elegans ortholog of regulatory associated protein of TOR (Raptor), to characterize its roles in aging. Global or tissue-specific inhibition of DAF-15 during development results in various growth defects, whereas neuron-specific knockdown of DAF-15 during adulthood significantly extends lifespan and healthspan. The neuronal DAF-15 deficiency-induced longevity requires the intestinal activities of DAF-16/FOXO and PHA-4/FOXA transcription factors, as well as the AAK-2/AMP-activated protein kinase (AMPK) α catalytic subunit. Transcriptome profiling revealed that the neuronal DAF-15 knockdown promotes expression of genes involved in protection. These findings define the tissue-specific roles of TORC1 in healthy aging and highlight the importance of neuronal modulation of aging.
    DOI:  https://doi.org/10.1016/j.jgg.2023.11.002
  65. Mol Neurodegener. 2023 Nov 11. 18(1): 83
    Mitochondrial dysfunction in Parkinson's disease - a key disease hallmark with therapeutic potential.
    Martin T Henrich, Wolfgang H Oertel, D James Surmeier, Fanni F Geibl.
      Mitochondrial dysfunction is strongly implicated in the etiology of idiopathic and genetic Parkinson's disease (PD). However, strategies aimed at ameliorating mitochondrial dysfunction, including antioxidants, antidiabetic drugs, and iron chelators, have failed in disease-modification clinical trials. In this review, we summarize the cellular determinants of mitochondrial dysfunction, including impairment of electron transport chain complex 1, increased oxidative stress, disturbed mitochondrial quality control mechanisms, and cellular bioenergetic deficiency. In addition, we outline mitochondrial pathways to neurodegeneration in the current context of PD pathogenesis, and review past and current treatment strategies in an attempt to better understand why translational efforts thus far have been unsuccessful.
    Keywords:  Antioxidants; Electron transport chain; MPTP; Mitochondria; Mitochondrial dysfunction; Neuroprotective therapies; Parkinson’s disease; Synuclein
    DOI:  https://doi.org/10.1186/s13024-023-00676-7
  66. Ecotoxicol Environ Saf. 2023 Nov 15. pii: S0147-6513(23)01190-9. [Epub ahead of print]268 115686
    DDIT4 is essential for DINP-induced autophagy of ovarian granulosa cells.
    Yijing Wang, Si Yang, Chaoju Hao, Jiaxiang Chen, Jinglei Wang, Linlin Xu.
      As one of the most important phthalates, di-isononyl phthalate (DINP) has been widely used as a common plasticizer in the food and personal care products sectors. In our previous study, we found that DINP can induce autophagy of ovarian granulosa cells; while the underlying mechanism is unclear. In the study, we showed that DINP exposure could induce autophagy of ovarian granulosa cells and KGN cells, accompanied with the increase in the mRNA and protein level of DDIT4. Furthermore, overexpression of DDIT4 were shown to induce autophagy of KGN cells; while knockdown of DDIT4 inhibited DINP-induced autophagy, implying that DDIT4 played an important role in DINP-induced autophagy of ovarian granulosa cells. There were three putative binding sites of transcription factor ATF4 in the promoter region of DDIT4 gene, suggesting that DDIT4 might be regulated by ATF4. Herein, we found that overexpression of ATF4 could upregulate the expression of DDIT4 in KGN cells, while knockdown of ATF4 inhibited its expression. Subsequently, ATF4 was identified to bind to the promoter region of DDIT4 gene and promote its transcription. The expression of ATF4 was also increased in the DINP-exposed granulosa cells, and ATF4 overexpression promoted autophagy of KGN cells; whereas knockdown of ATF4 alleviated DINP-induced upregulation of DDIT4 and autophagy of the cells. Taken together, DINP triggered autophagy of ovarian granulosa cells through activating ATF4/DDIT4 signals.
    Keywords:  ATF4; Autophagy; DDIT4; DINP; Ovarian granulosa cells
    DOI:  https://doi.org/10.1016/j.ecoenv.2023.115686
  67. Autophagy. 2023 Nov 16.
    Transcription factor FOXM1 specifies chromatin DNA to extracellular vesicles.
    Yunsheng Zhang, Nana Ding, Yizhen Li, Min Ouyang, Ping Fu, Yousong Peng, Yongjun Tan.
      Extracellular vesicle DNAs (evDNAs) hold significant diagnostic value for various diseases and facilitate transcellular transfer of genetic material. Our study identifies transcription factor FOXM1 as a mediator for directing chromatin genes or DNA fragments (termed FOXM1-chDNAs) to extracellular vesicles (EVs). FOXM1 binds to MAP1LC3/LC3 in the nucleus, and FOXM1-chDNAs, such as the DUX4 gene and telomere DNA, are designated by FOXM1 binding and translocated to the cytoplasm before being released to EVs through the secretory autophagy during lysosome inhibition (SALI) process involving LC3. Disrupting FOXM1 expression or the SALI process impairs FOXM1-chDNAs incorporation into EVs. FOXM1-chDNAs can be transmitted to recipient cells via EVs and expressed in recipient cells when they carry functional genes. This finding provides an example of how chromatin DNA fragments are specified to EVs by transcription factor FOXM1, revealing its contribution to the formation of evDNAs from nuclear chromatin. It provides a basis for further exploration of the roles of evDNAs in biological processes, such as horizontal gene transfer.
    Keywords:  Evs; FOXM1; FOXM1-chDnas; LC3; SALI; evDnas
    DOI:  https://doi.org/10.1080/15548627.2023.2284523
  68. Mol Cells. 2023 Nov 30. 46(11): 664-671
    The Role of mRNA Quality Control in the Aging of Caenorhabditis elegans.
    Hyunwoo C Kwon, Yunkyu Bae, Seung-Jae V Lee.
      The proper maintenance of mRNA quality that is regulated by diverse surveillance pathways is essential for cellular homeostasis and is highly conserved among eukaryotes. Here, we review findings regarding the role of mRNA quality control in the aging and longevity of Caenorhabditis elegans, an outstanding model for aging research. We discuss the recently discovered functions of the proper regulation of nonsense-mediated mRNA decay, ribosome-associated quality control, and mRNA splicing in the aging of C. elegans. We describe how mRNA quality control contributes to longevity conferred by various regimens, including inhibition of insulin/insulin-like growth factor 1 (IGF-1) signaling, dietary restriction, and reduced mechanistic target of rapamycin signaling. This review provides valuable information regarding the relationship between the mRNA quality control and aging in C. elegans, which may lead to insights into healthy longevity in complex organisms, including humans.
    Keywords:  Caenorhabditis elegans; aging; alternative splicing; mRNA surveillance; nonsense-mediated mRNA decay; ribosome-associated quality control
    DOI:  https://doi.org/10.14348/molcells.2023.0103
  69. Cell Death Dis. 2023 Nov 14. 14(11): 740
    Inhibition of Hedgehog signaling ameliorates foam cell formation by promoting autophagy in early atherosclerosis.
    Yuting Zhang, Weijuan Xin, Xiaozhi Hu, Hanqi Wang, Xiaomiao Ye, Caili Xu, Yanyang Nan, Zhengyu Wu, Dianwen Ju, Jiajun Fan.
      Macrophages are the origin of most foam cells in the early stage of atherosclerotic plaques. However, the mechanism involved in the formation of macrophage-derived foam cell formation remains unclear. Here, we revealed that the hedgehog (Hh) signaling is critical in autophagy-lysosome pathway regulation and macrophage-derived foam cell formation. Inhibition of Hh signaling by vismodegib ameliorated lipid deposition and oxidative stress level in atherosclerotic plaques in high-fat diet-fed apoE-/- mice. For mechanistic study, how the Hh signaling modulate the process of foam cell formation were accessed afterward. Unexpectedly, we found that suppression of Hh signaling in apoE-/- mice had no significant impact on circulating cholesterol levels, indicating that Hh pathway modulate the procession of atherosclerotic plaque not through a traditional lipid-lowing mechanism. Instead, vismodegib was found to accelerate autophagosomes maturation as well as cholesterol efflux in macrophage-derived foam cell and in turn improve foam cell formation, while autophagy inhibitors (LY294002 or CQ) administration significantly attenuated vismodegib-induced cholesterol efflux and reversed the effect on foam cell formation. Therefore, our result demonstrated that inhibition of the Hh signaling pathway increases cholesterol efflux and ameliorates macrophage-derived foam cell formation by promoting autophagy in vitro. Our data thus suggested a novel therapeutic target of atherosclerosis and indicated the potential of vismodegib to treat atherosclerosis.
    DOI:  https://doi.org/10.1038/s41419-023-06270-5
  70. Cell Rep. 2023 Nov 10. pii: S2211-1247(23)01448-1. [Epub ahead of print]42(11): 113436
    Skeletal muscle TFEB signaling promotes central nervous system function and reduces neuroinflammation during aging and neurodegenerative disease.
    Ian Matthews, Allison Birnbaum, Anastasia Gromova, Amy W Huang, Kailin Liu, Eleanor A Liu, Kristen Coutinho, Megan McGraw, Dalton C Patterson, Macy T Banks, Amber C Nobles, Nhat Nguyen, Gennifer E Merrihew, Lu Wang, Eric Baeuerle, Elizabeth Fernandez, Nicolas Musi, Michael J MacCoss, Helen C Miranda, Albert R La Spada, Constanza J Cortes.
      Skeletal muscle has recently arisen as a regulator of central nervous system (CNS) function and aging, secreting bioactive molecules known as myokines with metabolism-modifying functions in targeted tissues, including the CNS. Here, we report the generation of a transgenic mouse with enhanced skeletal muscle lysosomal and mitochondrial function via targeted overexpression of transcription factor E-B (TFEB). We discovered that the resulting geroprotective effects in skeletal muscle reduce neuroinflammation and the accumulation of tau-associated pathological hallmarks in a mouse model of tauopathy. Muscle-specific TFEB overexpression significantly ameliorates proteotoxicity, reduces neuroinflammation, and promotes transcriptional remodeling of the aged CNS, preserving cognition and memory in aged mice. Our results implicate the maintenance of skeletal muscle function throughout aging in direct regulation of CNS health and disease and suggest that skeletal muscle originating factors may act as therapeutic targets against age-associated neurodegenerative disorders.
    Keywords:  CP: Neuroscience; TFEB; aging; brain; exercise; muscle; neurodegeneration; tau
    DOI:  https://doi.org/10.1016/j.celrep.2023.113436
  71. Oncogene. 2023 Nov 16.
    Targeting DGAT1 inhibits prostate cancer cells growth by inducing autophagy flux blockage via oxidative stress.
    Haiying Cui, Yao Wang, Tong Zhou, Limei Qu, Xiaoling Zhang, Yingdi Wang, Mingyue Han, Shuo Yang, Xinhua Ren, Guixia Wang, Xiaokun Gang.
      Impaired macroautophagy/autophagy flux has been implicated in the treatment of prostate cancer (PCa). However, the mechanism underlying autophagy dysregulation in PCa remains unknown. In the current study, we investigated the role of diacylglycerol acyltransferases 1 (DGAT1) and its potential effects on cellular energy homeostasis and autophagy flux in PCa. The results of immunohistochemical staining suggested that DGAT1 expression was positively corrected with tumor stage and node metastasis, indicating DGAT1 is an important factor involved in the development and progression of PCa. Furthermore, targeting DGAT1 remarkably inhibited cell proliferation in vitro and suppressed PCa growth in xenograft models by triggering severe oxidative stress and subsequently autophagy flux blockage. Mechanically, DGAT1 promoted PCa progression by maintaining cellular energy homeostasis, preserving mitochondrial function, protecting against reactive oxygen species, and subsequently promoting autophagy flux via regulating lipid droplet formation. Moreover, we found that fenofibrate exhibits as an upstream regulator of DGAT1. Fenofibrate performed its anti-PCa effect involved the aforementioned mechanisms, and partially dependent on the regulation of DGAT1. Collectively. These findings indicate that DGAT1 regulates PCa lipid droplets formation and is essential for PCa progression. Targeting DGAT1 might be a promising method to control the development and progression of PCa. Schematic representation of DGAT1 affects autophagy flux by regulating lipid homeostasis and maintaining mitochondrial function in prostate cancer (PCa). PCa is characterized up-regulation of DGAT1, leading to the translocation of free fatty acids into lipid droplets, thereby preventing PCa cell from lipotoxicity. Inhibition of DGAT1 suppresses growth of PCa by inducing oxidative stress and subsequently autophagy flux blockage. Further, the current results revealed that fenofibrate exhibits as an upstream regulator of DGAT1, and fenofibrate plays an anti-PCa role partially dependent on the regulation of DGAT1, suggesting a potential therapeutic approach to ameliorate this refractory tumor.
    DOI:  https://doi.org/10.1038/s41388-023-02878-1
  72. bioRxiv. 2023 Nov 01. pii: 2023.10.27.564485. [Epub ahead of print]
    Adjusted vascular contractility relies on integrity of progranulin pathway: Insights into mitochondrial function.
    Shubhnita Singh, Ariane Bruder-Nascimento, Rafael M Costa, Juliano V Alves, Sivakama Bharathi, Eric S Goetzman, Thiago Bruder-Nascimento.
      Objective: Cardiovascular disease (CVD) is a global health crisis and a leading cause of mortality. The intricate interplay between vascular contractility and mitochondrial function is central to CVD pathogenesis. The progranulin gene (GRN) encodes glycoprotein progranulin (PGRN), a ubiquitous molecule with known anti-inflammatory property. However, the role of PGRN in CVD remains enigmatic. In this study, we sought to dissect the significance of PGRN in the regulation vascular contractility and investigate the interface between PGRN and mitochondrial quality.Method: Our investigation utilized aortae from male and female C57BL6/J wild-type (PGRN+/+) and B6(Cg)-Grntm1.1Aidi/J (PGRN-/-) mice, encompassing wire myograph assays to assess vascular contractility and primary aortic vascular smooth muscle cells (VSMCs) for mechanistic insights.
    Results: Our results showed suppression of contractile activity in PGRN-/- VSMCs and aorta, followed by reduced α-smooth muscle actin expression. Mechanistically, PGRN deficiency impaired mitochondrial oxygen consumption rate (OCR), complex I activity, mitochondrial turnover, and mitochondrial redox signaling, while restoration of PGRN levels in aortae from PGRN-/- mice via lentivirus delivery ameliorated contractility and boosted OCR. In addition, VSMC overexpressing PGRN displayed higher mitochondrial respiration and complex I activity accompanied by cellular hypercontractility. Furthermore, increased PGRN triggered lysosome biogenesis by regulating transcription factor EB and accelerated mitophagy flux in VSMC, while treatment with spermidine, an autophagy inducer, improved mitochondrial phenotype and enhanced vascular contractility. Finally, angiotensin II failed to induce vascular contractility in PGRN-/- suggesting a key role of PGRN to maintain the vascular tone.
    Conclusion: Our findings suggest that PGRN preserves the vascular contractility via regulating mitophagy flux, mitochondrial complex I activity, and redox signaling. Therefore, loss of PGRN function appears as a pivotal risk factor in CVD development.
    DOI:  https://doi.org/10.1101/2023.10.27.564485
  73. JACC CardioOncol. 2023 Oct;5(5): 671-673
    ER-Specific Autophagy or ER-Phagy in Cardiac Myocytes Protects the Heart Against Doxorubicin-Induced Cardiotoxicity.
    Christopher C Glembotski, Sukriti Bagchi, Erik A Blackwood.
      
    Keywords:  anthracycline; cardiomyopathy; heart failure; mechanisms; preclinical study
    DOI:  https://doi.org/10.1016/j.jaccao.2023.08.004
  74. Cell Insight. 2023 Dec;2(6): 100127
    CPT1A mediates chemoresistance in human hypopharyngeal squamous cell carcinoma via ATG16L1-dependent cellular autophagy.
    Lianhui Sun, Xing Wang, Lixiao Chen, Zheng Gao, Songhui Xu, Chen Hu, Guangjian Fan, Baoxin Wang, Tingting Feng, Wang Wang, Xinjiang Ying.
      Hypopharyngeal squamous cell carcinoma (HSCC) is a highly aggressive malignancy that constitutes approximately 95% of all hypopharyngeal carcinomas, and it carries a poor prognosis. The primary factor influencing the efficacy of anti-cancer drugs for this type of carcinoma is chemoresistance. Carnitine palmitoyltransferase 1A (CPT1A) has been associated with tumor progression in various cancers, including breast, gastric, lung, and prostate cancer. The inhibition or depletion of CPT1A can lead to apoptosis, curbing cancer cell proliferation and chemoresistance. However, the role of CPT1A in HSCC is not yet fully understood. In this study, we discovered that CPT1A is highly expressed in HSCC and is associated with an advanced T-stage and a poor 5-year survival rate among patients. Furthermore, the overexpression of CPT1A contributes to HSCC chemoresistance. Mechanistically, CPT1A can interact with the autophagy-related protein ATG16L1 and stimulate the succinylation of ATG16L1, which in turn drives autophagosome formation and autophagy. We also found that treatment with 3-methyladenine (3-MA) can reduce cisplatin resistance in HSCC cells that overexpress CPT1A. Our findings also showed that a CPT1A inhibitor significantly enhances cisplatin sensitivity both in vitro and in vivo. This study is the first to suggest that CPT1A has a regulatory role in autophagy and is linked to poor prognosis in HSCC patients. It presents novel insights into the roles of CPT1A in tumorigenesis and proposes that CPT1A could be a potential therapeutic target for HSCC treatment.
    DOI:  https://doi.org/10.1016/j.cellin.2023.100127
  75. J Adv Res. 2023 Nov 11. pii: S2090-1232(23)00329-6. [Epub ahead of print]
    Unlocking the Secrets of Aging: Epigenetic Reader BRD4 as the Target to Combatting Aging-Related Diseases.
    Jiaxing Sun, Yu Gui, Shenghua Zhou, Xi-Long Zheng.
      BACKGROUND: Aging, a complex and profound journey, leads us through a labyrinth of physiological and pathological transformations, rendering us increasingly susceptible to aging-related diseases. Emerging investigations have unveiled the function of bromodomain containing protein 4 (BRD4) in manipulating the aging process and driving the emergence and progression of aging-related diseases.AIM: of review: This review aims to offer a comprehensive outline of BRD4's functions involved in the aging process, and potential mechanisms through which BRD4 governs the initiation and progression of various aging-related diseases. Key scientific concepts of review: BRD4 has a fundamental role in regulating the cell cycle, apoptosis, cellular senescence, the senescence-associated secretory phenotype (SASP), senolysis, autophagy, and mitochondrial function, which are involved in the aging process. Several studies have indicated that BRD4 governs the initiation and progression of various aging-related diseases, including Alzheimer's disease, ischemic cerebrovascular diseases, hypertension, atherosclerosis, heart failure, aging-related pulmonary fibrosis, and intervertebral disc degeneration (IVDD). Thus, the evidence from this review supports that BRD4 could be a promising target for managing various aging-related diseases, while further investigation is warranted to gain a thorough understanding of BRD4's role in these diseases.
    Keywords:  BRD4; aging-related diseases; autophagy; inflammation; senescence
    DOI:  https://doi.org/10.1016/j.jare.2023.11.006
  76. Acta Pharm Sin B. 2023 Nov;13(11): 4477-4501
    Miriplatin-loaded liposome, as a novel mitophagy inducer, suppresses pancreatic cancer proliferation through blocking POLG and TFAM-mediated mtDNA replication.
    Xiaowei Wang, Mengyan Wang, Meilian Cai, Rongguang Shao, Guimin Xia, Wuli Zhao.
      Pancreatic cancer is a more aggressive and refractory malignancy. Resistance and toxicity limit drug efficacy. Herein, we report a lower toxic and higher effective miriplatin (MPt)-loaded liposome, LMPt, exhibiting totally different anti-cancer mechanism from previously reported platinum agents. Both in gemcitabine (GEM)-resistant/sensitive (GEM-R/S) pancreatic cancer cells, LMPt exhibits prominent anti-cancer activity, led by faster cellular entry-induced larger accumulation of MPt. The level of caveolin-1 (Cav-1) determines entry rate and switch of entry pathways of LMPt, indicating a novel role of Cav-1 in nanoparticle entry. After endosome-lysosome processing, in unchanged metabolite, MPt is released and targets mitochondria to enhance binding of mitochondria protease LONP1 with POLG and TFAM, to degrade POLG and TFAM. Then, via PINK1-Parkin axis, mitophagy is induced by POLG and TFAM degradation-initiated mitochondrial DNA (mtDNA) replication blocking. Additionally, POLG and TFAM are identified as novel prognostic markers of pancreatic cancer, and mtDNA replication-induced mitophagy blocking mediates their pro-cancer activity. Our findings reveal that the target of this liposomal platinum agent is mitochondria but not DNA (target of most platinum agents), and totally distinct mechanism of MPt and other formulations of MPt. Self-assembly offers LMPt special efficacy and mechanisms. Prominent action and characteristic mechanism make LMPt a promising cancer candidate.
    Keywords:  Caveolae-mediated endocytosis; Caveolin-1; Miriplatin-loaded liposome; Mitochondria DNA; Mitophagy; POLG; Pancreatic cancer; TFAM
    DOI:  https://doi.org/10.1016/j.apsb.2023.07.009
  77. Food Chem Toxicol. 2023 Nov 15. pii: S0278-6915(23)00579-3. [Epub ahead of print] 114177
    ZnO nanoparticles impair autophagic flux and cell viability through the TRIM16-NRF2-p62 pathway in inflammatory keratinocytes.
    Menglei Wang, Huanxin Zheng, Jiawen Chen, Yingmei Tang, Meixin Feng, Li Li.
      PURPOSE: Zinc oxide nanoparticles (ZnO NPs) are widely used in sunscreen, cosmetics, and topical drugs. Most previous studies have confirmed the safety of ZnO NPs applied to normal skin; however, little is known about the safety and potential toxicity of ZnO NPs applied to inflamed skin. This study aimed to evaluate the exposure risk of ZnO NPs in the treatment of inflammatory skin diseases.METHODS: Normal human and tumor necrosis factor-α (TNF-α)-induced inflammatory keratinocytes were incubated with ZnO NPs to assess their toxic effects on cell viability and autophagy signaling pathway. Tandem mass tag (TMT)-based proteomics analysis was used to identify differentially expressed proteins following incubation of inflammatory keratinocytes with ZnO NPs. Protein expression was assessed by Western blot, and double fluorescent labeling and siRNA-knockdown further elucidated the role of the TRIM16-NRF2-p62 pathway in mediating the effects of ZnO NP.
    RESULTS: In TNF-α-induced inflammatory keratinocytes, ZnO NPs activated cytoprotective autophagy and mediated p62-related autophagic flux block, thereby reducing the viability of inflammatory keratinocytes. Additionally, TRIM16-NRF2 was essential in ZnO NP-mediated autophagy flux block and cell viability reduction in inflammatory keratinocytes. Inhibition of the TRIM16-NRF2 pathway reduced p62 levels, alleviated autophagy flux blockade, and slightly restored the viability of inflammatory keratinocytes.
    CONCLUSION: ZnO NPs activated protective cell autophagy. Blockade of autophagy flux mediated by the TRIM16-NRF2-p62 pathway led to decreased cell viability. This study provided a deeper understanding of the toxicity mechanism of ZnO NPs in inflammatory keratinocytes.
    Keywords:  Autophagy; Cytotoxicity; Inflammation; Inflammatory keratinocytes; Toxicity
    DOI:  https://doi.org/10.1016/j.fct.2023.114177
  78. Biochim Biophys Acta Mol Cell Res. 2023 Nov 12. pii: S0167-4889(23)00200-8. [Epub ahead of print] 119627
    Inhibition of autophagy initiation: A novel strategy for oral squamous cell carcinomas.
    Yomna S Abd El-Aziz, Matthew Mckay, Mark P Molloy, Betty McDowell, Elizabeth Moon, Loretta Sioson, Amy Sheen, Angela Chou, Anthony J Gill, Patric J Jansson, Sumit Sahni.
      BACKGROUND: Oral squamous cell carcinoma (OSCC) is one of the most common forms of oral cancer and is known to have poor prognostic outcomes. Autophagy is known to be associated with aggressive tumor biology of OSCC. Hence, this study aimed to develop a novel therapeutic strategy against OSCC by targeting the autophagic pathway.METHODS: Immunoblotting, and confocal microscopy were used to examine the effect of tumor microenvironmental stressors on the autophagy activity. Cellular proliferation and migration assays were performed to assess the anti-cancer activity of standard chemotherapy and autophagy initiation inhibitors, either alone or in combination. High resolution mass-spectrometry based proteomic analysis was utilized to understand the mechanisms behind chemoresistance in OSCC models. Finally, immunohistochemistry was performed to determine associations between autophagy markers and clinicopathological characteristics.
    RESULTS: Tumor microenvironmental stressors were shown to induce autophagy activity in OSCC cell lines. Novel combinations of chemotherapy and autophagy inhibitors as well as different classes of autophagy inhibitors were identified. Combination of MRT68921 and SAR405 demonstrated marked synergy in their anti-proliferative activity and also showed synergy with chemotherapy in chemoresistant OSCC cell models. Autophagy was identified as one of the key pathways involved in mediating chemoresistance in OSCC. Furthermore, TGM2 was identified as a key upstream regulator of chemoresistance in OSCC models. Finally, positive staining for autophagosome marker LC3 was shown to be associated with low histological grade OSCC.
    CONCLUSION: In conclusion, this study identified a combination of novel autophagy inhibitors which can potently inhibit proliferation of both chemosensitive as well as chemoresistant OSCC cells and could be developed as a novel therapy against advanced OSCC tumors.
    Keywords:  Autophagy; Autophagy inhibitors; Chemotherapy resistance; Oral squamous cell carcinoma; Proteomics; Tumor microenvironment stress
    DOI:  https://doi.org/10.1016/j.bbamcr.2023.119627
  79. Proc Natl Acad Sci U S A. 2023 Nov 21. 120(47): e2316011120
    TORC pathway intersects with a calcium sensor kinase network to regulate potassium sensing in Arabidopsis.
    Kun-Lun Li, Hui Xue, Ren-Jie Tang, Sheng Luan.
      Potassium (K) is an essential macronutrient for plant growth, and its availability in the soil varies widely, requiring plants to respond and adapt to the changing K nutrient status. We show here that plant growth rate is closely correlated with K status in the medium, and this K-dependent growth is mediated by the highly conserved nutrient sensor, target of rapamycin (TOR). Further study connected the TOR complex (TORC) pathway with a low-K response signaling network consisting of calcineurin B-like proteins (CBL) and CBL-interacting kinases (CIPK). Under high K conditions, TORC is rapidly activated and shut down the CBL-CIPK low-K response pathway through regulatory-associated protein of TOR (RAPTOR)-CIPK interaction. In contrast, low-K status activates CBL-CIPK modules that in turn inhibit TORC by phosphorylating RAPTOR, leading to dissociation and thus inactivation of the TORC. The reciprocal regulation of the TORC and CBL-CIPK modules orchestrates plant response and adaptation to K nutrient status in the environment.
    Keywords:  TOR; calcium signaling; nutrient sensing; protein kinases
    DOI:  https://doi.org/10.1073/pnas.2316011120
  80. Proc Natl Acad Sci U S A. 2023 Nov 21. 120(47): e2315347120
    Mitochondria-associated membrane collapse impairs TBK1-mediated proteostatic stress response in ALS.
    Seiji Watanabe, Yuri Murata, Yasuyoshi Oka, Kotaro Oiwa, Mai Horiuchi, Yohei Iguchi, Okiru Komine, Akira Sobue, Masahisa Katsuno, Tomoo Ogi, Koji Yamanaka.
      The organelle contact site of the endoplasmic reticulum and mitochondria, known as the mitochondria-associated membrane (MAM), is a multifunctional microdomain in cellular homeostasis. We previously reported that MAM disruption is a common pathological feature in amyotrophic lateral sclerosis (ALS); however, the precise role of MAM in ALS was uncovered. Here, we show that the MAM is essential for TANK-binding kinase 1 (TBK1) activation under proteostatic stress conditions. A MAM-specific E3 ubiquitin ligase, autocrine motility factor receptor, ubiquitinated nascent proteins to activate TBK1 at the MAM, which results in ribosomal protein degradation. MAM or TBK1 deficiency under proteostatic stress conditions resulted in increased cellular vulnerability in vitro and motor impairment in vivo. Thus, MAM disruption exacerbates proteostatic stress via TBK1 inactivation in ALS. Our study has revealed a proteostatic mechanism mediated by the MAM-TBK1 axis, highlighting the physiological importance of the organelle contact sites.
    Keywords:  TANK-binding kinase 1; amyotrophic lateral sclerosis; mitochondria-associated membrane; sigma-1 receptor; stress granules
    DOI:  https://doi.org/10.1073/pnas.2315347120
  81. Hippocampus. 2023 Nov 14.
    Hippocampal TMEM55B overexpression in the 5XFAD mouse model of Alzheimer's disease.
    Kristian F Odfalk, Jessica L Wickline, Sabrina Smith, Radek Dobrowolski, Sarah C Hopp.
      Dysfunction of the endosomal-lysosomal network is a notable feature of Alzheimer's disease (AD) pathology. Dysfunctional endo-lysosomal vacuoles accumulate in dystrophic neurites surrounding amyloid β (Aβ) plaques and may be involved in the pathogenesis and progression of Aβ aggregates. Trafficking and thus maturation of these dysfunctional vacuoles is disrupted in the vicinity of Aβ plaques. Transmembrane protein 55B (TMEM55B), also known as phosphatidylinositol-4,5-bisphosphate 4-phosphatase 1 (PIP4P1) is an endo-lysosomal membrane protein that is necessary for appropriate trafficking of endo-lysosomes. The present study tested whether overexpression of TMEM55B in the hippocampus could prevent plaque-associated axonal accumulation of dysfunctional endo-lysosomes, reduce Aβ plaque load, and prevent hippocampal-dependent learning and memory deficits in the 5XFAD mouse models of Aβ plaque pathology. Immunohistochemical analyses revealed a modest but significant reduction in the accumulation of endo-lysosomes in dystrophic neurites surrounding Aβ plaques, but there was no change in hippocampal-dependent memory or plaque load. Overall, these data indicate a potential role for TMEM55B in reducing endo-lysosomal dysfunction during AD-like Aβ pathology.
    Keywords:  Alzheimer's disease; Aβ; PIP4P1; TMEM55B; lysosomes
    DOI:  https://doi.org/10.1002/hipo.23586
  82. BMC Res Notes. 2023 Nov 16. 16(1): 338
    Placental extract suppresses lipid droplet accumulation by autophagy during the differentiation of adipose-derived mesenchymal stromal/stem cells into mature adipocytes.
    Yusuke Ando, Eri Odawara, Hiroyasu Sakai, Fumiaki Sato, Junzo Kamei.
      OBJECTIVE: Placental extract, which contains various bioactive compounds, has been used as traditional medicine. Many studies have demonstrated additional applications of placental extract and provided a scientific basis for the broad spectrum of its effects. We have previously reported that porcine placental extract (PPE) strongly suppresses adipogenesis in a 3T3-L1 preadipocyte cell line, inhibiting differentiation. This study aimed to examine the effect of PPE on the accumulation of lipid droplets (LD) in adipose-derived mesenchymal stromal/stem cells (ASC).RESULTS: The study findings revealed that PPE decreased the size of LD during the differentiation of ASC into mature adipocytes. RT-qPCR analysis revealed that PPE increased the gene expression of lysosomal acid lipase A (Lipa), a lipolysis-related gene, in ASC-differentiated adipocytes. However, no differences were noted in the adipocyte differentiation markers (Pparg, Cebpa, and Adipoq), or the adipogenesis-related genes (Dgat1, Dgat2, Fasn, Soat1, and Soat2). In addition, PPE promoted autophagosome formation, which was partially co-localized with the LD, indicating that PPE accelerated the degradation of LD by inducing autophagy (termed lipophagy) during the differentiation of ASC into mature adipocytes. These results suggest that the use of PPE may be a potential novel treatment for regulating adipogenesis for the treatment of obesity.
    Keywords:  Adipogenesis; Adipose-derived mesenchymal stromal/stem cells; Autophagy; Lipolysis; Lysosomal acid lipase A; Placental extract
    DOI:  https://doi.org/10.1186/s13104-023-06622-6
  83. Mol Biomed. 2023 Nov 17. 4(1): 42
    Aloperine targets lysosomes to inhibit late autophagy and induces cell death through apoptosis and paraptosis in glioblastoma.
    Ting Tang, Hui Liang, Wuting Wei, Yanling Han, Liang Cao, Zixiang Cong, Shiqiao Luo, Handong Wang, Meng-Liang Zhou.
      Glioblastoma (GBM) is an aggressive intracranial tumour, and current chemotherapy regimens have limited efficacy. Aloperine (ALO), a natural alkaline compound, has shown potential as an antitumor agent. However, the effect of ALO against GBM remains unclear. This study aimed to investigate the function of ALO in treating GBM. U87, A172, and GL261 cell lines were used for in vitro experiments, and GL261 was also used to establish in vivo models. The results showed that ALO inhibited the proliferation of GBM cells by cell cycle arrest and apoptosis. Furthermore, autophagy was found to play a critical role, suggested by observation of autophagosomes under the transmission electron microscopy. It was discovered for the first time that ALO targeted lysosomes directly in glioma cells, tested by fluo-rescence-labelled ALO and organelle-localizing probes. In addition, ALO inhibited late autophagy and induced paraptosis in GBM, verified by classical gene expression changes in qPCR and western blotting. Also, ALO inhibited tumour growth and acted synergistically with temozolomide in intracranial glioma mice models in vivo. Our findings suggest that ALO targets lysosomes to inhibit late autophagy in GBM, inducing cell cycle arrest, paraptosis, and apoptosis. ALO may therefore be a promising therapeutic agent for the treatment of GBM.
    Keywords:  Aloperine; Autophagy; Glioblastoma; Lysosome; Paraptosis
    DOI:  https://doi.org/10.1186/s43556-023-00155-x
  84. Am J Physiol Regul Integr Comp Physiol. 2023 Nov 13.
    The intensity-dependent effects of exercise and superimposing environmental heat stress on autophagy in peripheral blood mononuclear cells from older men.
    James J McCormick, Morgan K McManus, Kelli E King, Nicholas Goulet, Glen P Kenny.
      Autophagy is a vital cellular process, essential to maintaining cellular function during acute physiological stressors including exercise and heat stress. We previously showed that autophagy occurs during exercise in an intensity-dependent manner in peripheral blood mononuclear cells (PBMCs) from young men, with elevated responses in the heat. However, given autophagy declines with age, it is unclear whether a similar pattern of response occurs in older adults. Therefore, we evaluated autophagy and the cellular stress response (i.e., apoptosis, inflammation, and the heat shock response [HSR]) in PBMCs from 10 healthy older men (mean [SD]: aged 70 years [5]) in response to 30 minutes of semi-recumbent cycling at low-, moderate-, and vigorous-intensities (40, 55, and 70% maximal oxygen consumption (VO2max), respectively) in a temperate (25°C) environment, with an additional vigorous-intensity bout (70% of VO2max) performed in a hot environment (40°C). Responses were evaluated before and after exercise, as well as throughout a 6-hour seated recovery period performed in the same environmental conditions as the respective exercise bout. Proteins were assessed via Western blot. While we observed elevations in mean body temperature with each increase in exercise intensity, autophagy was only stimulated during vigorous-intensity exercise, where we observed elevations in LC3-II (p<0.05). However, when the same exercise was performed in the heat, the LC3-II response was attenuated, which was accompanied by significant p62 accumulation (p<0.05). Altogether, our findings demonstrate that older adults exhibit autophagic impairments when the same vigorous-intensity exercise is performed in hot environments, potentially underlying heat-induced cellular vulnerability in older men.
    Keywords:  apoptosis; autophagy; exercise; heat shock response; older adults
    DOI:  https://doi.org/10.1152/ajpregu.00163.2023
  85. Biochim Biophys Acta Gen Subj. 2023 Nov 10. pii: S0304-4165(23)00217-9. [Epub ahead of print] 130519
    FAT1 inhibits AML autophagy and proliferation via downregulating ATG4B expression.
    Nan Zhang, Meng-Yu Shen, Qing-Li Meng, Hao-Ping Sun, Fang-Yi Fan, Hai Yi, Yong-Jian Yang.
      BACKGROUND: Emerging studies have shown that FAT atypical cadherin 1 (FAT1) and autophagy separately inhibits and promotes acute myeloid leukemia (AML) proliferation. However, it is unknown whether FAT1 were associated with autophagy in regulating AML proliferation.METHODS: AML cell lines, 6-week-old male nude mice and AML patient samples were used in this study. qPCR/Western blot and cell viability/3H-TdR incorporation assays were separately used to detect mRNA/protein levels and cell activity/proliferation. Luciferase reporter assay was used to examine gene promoter activity. Co-IP analysis was used to detect the binding of proteins.
    RESULTS: In this study, we for the first time demonstrated that FAT1 inhibited AML proliferation by decreasing AML autophagy level. Moreover, FAT1 weakened AML autophagy level via decreasing autophagy related 4B (ATG4B) expression. Mechanistically, we found that FAT1 reduced the phosphorylated and intranuclear SMAD family member 2/3 (smad2/3) protein levels, thus decreasing the activity of ATG4B gene promoter. Furthermore, we found that FAT1 competitively bound to TGF-βR II which decreased the binding of TGF-βR II to TGF-βR I and the subsequent phosphorylation of TGF-βR I, thus reducing the phosphorylation and intranuclear smad2/3. The experiments in nude mice showed that knockdown of FAT1 promoted AML autophagy and proliferation in vivo.
    CONCLUSIONS: Collectively, these results revealed that FAT1 downregulates ATG4B expression via inhibiting TGFβ-smad2/3 signaling activity, thus decreasing the autophagy level and proliferation activity of AML cells.
    GENERAL SIGNIFICANCE: Our study suggested that the "FAT1-TGFβ-smad2/3-ATG4B-autophagy" pathway may be a novel target for developing new targeted drugs to AML treatment.
    Keywords:  Acute myeloid leukemia (AML); Autophagy; Autophagy related 4B (ATG4B); FAT atypical cadherin 1 (FAT1); SMAD family member 2/3 (smad2/3); TGF-β receptor I/II (TGF-βR I/II)
    DOI:  https://doi.org/10.1016/j.bbagen.2023.130519
  86. JACC CardioOncol. 2023 Oct;5(5): 656-670
    Endoplasmic Reticulum Selective Autophagy Alleviates Anthracycline-Induced Cardiotoxicity.
    Shun Nakagama, Yasuhiro Maejima, Qintao Fan, Yuka Shiheido-Watanabe, Natsuko Tamura, Kensuke Ihara, Tetsuo Sasano.
      Background: The administration of anthracycline drugs induces progressive and dose-related cardiac damage through several cytotoxic mechanisms, including endoplasmic reticulum (ER) stress. The unfolded protein response plays a crucial role for mitigating misfolded protein accumulation induced by excessive ER stress.Objectives: We aimed to clarify whether endoplasmic reticulum-selective autophagy machinery (ER-phagy) serves as an alternative system to protect cardiomyocytes from ER stress caused by anthracycline drugs.
    Methods: Primary cultured cardiomyocytes, H9c2 cell lines, and cardiomyocyte-specific transgenic mice, all expressing ss-RFP-GFP-KDEL proteins, were used as ER-phagy reporter models. We generated loss-of-function models using RNA interference or gene-trap mutagenesis techniques. We assessed phenotypes and molecular signaling pathways using immunoblotting, quantitative polymerase chain reaction, cell viability assays, immunocytochemical and histopathological analyses, and cardiac ultrasonography.
    Results: The administration of doxorubicin (Dox) activated ER-phagy in ss-RFP-GFP-KDEL-transduced cardiomyocytes. In addition, Dox-induced cardiomyopathy models of ER-phagy reporter mice showed marked activation of ER-phagy in the myocardium compared to those of saline-treated mice. Quantitative polymerase chain reaction analyses revealed that Dox enhanced the expression of cell-cycle progression gene 1 (CCPG1), one of the ER-phagy receptors, in H9c2 cells. Ablation of CCPG1 in H9c2 cells resulted in the reduced ER-phagy activity, accumulation of proapoptotic proteins, and deterioration of cell survival against Dox administration. CCPG1-hypomorphic mice developed more severe deterioration in systolic function in response to Dox compared to wild-type mice.
    Conclusions: Our findings highlight a compensatory role of CCPG1-driven ER-phagy in reducing Dox toxicity. With further study, ER-phagy may be a potential therapeutic target to mitigate Dox-induced cardiomyopathy.
    Keywords:  CCPG1; autophagy; doxorubicin; endoplasmic reticulum
    DOI:  https://doi.org/10.1016/j.jaccao.2023.05.009
  87. Int Immunopharmacol. 2023 Nov 15. pii: S1567-5769(23)01537-0. [Epub ahead of print]125(Pt B): 111210
    Melatonin-mediated mitophagy protects against long-term impairments after repeated neonatal sevoflurane exposures.
    Hui Zhang, Yingqiao Niu, Lili Qiu, Jiaojiao Yang, Jie Sun, Jiangyan Xia.
      BACKGROUND: Melatonin is known to have protective effects in aging, neurodegenerative disorders and mitochondria-related diseases, while there is a poor understanding of the effects of melatonin treatment on mitophagy in neonatal cognitive dysfunction after repeated sevoflurane exposures. This study explores the protective effects of melatonin on mitophagy and cognition in developing rats exposed to sevoflurane.METHODS: Postnatal day six (P6) neonatal rats were exposed to 3 % sevoflurane for 2 h daily from P6 to P8. In the intervention groups, rats received 3-Methyladenine (3-MA) intracerebroventricularly from P6 to P8 and melatonin intraperitoneally from P6 to P8 following water drinking once daily from P21 to P41, respectively. Behavioral tests, including open field (OF), novel object recognition (NOR), and fear conditioning (FC) tests, were performed to assess cognitive function during young adulthood. In another experiment, rat brains were harvested for biochemical, histopathological, and electron microscopy studies.
    RESULTS: Rats exposed to sevoflurane showed disordered mitophagy and mitochondrial dysfunction as revealed by increased mitophagy marker proteins (microtubule-associated protein 1 light chain 3 (LC3) II/I, and parkin), decreased autophagy marker protein (sequestosome 1 (P62/SQSTM1)), electron transport chain (ETC) proteins and ATP levels. Immunofluorescent staining of LC3 was co-localized mostly with a neuronal marker and microglial marker but was not co-localized with a marker for astrocytes in rats exposed to sevoflurane. These rats had poorer performance in the NOR and FC tests than control rats during young adulthood. Melatonin treatment reversed the abnormal expression of mitophagy proteins, mitochondrial energy metabolism, the activity of microglia, and impaired cognition. These ameliorations were blocked by an autophagy inhibitor, 3-MA, except for the activation of microglia.
    CONCLUSION: We have demonstrated that melatonin inhibits microglial activation by enhancing mitophagy and finally significantly reduces sevoflurane-induced deficits in cognition in neonatal rats. These results suggest that melatonin might be beneficial if considered when the anesthesia must be administered at a very young age.
    Keywords:  Cognitive dysfunction; Melatonin; Mitophagy; Neonatal; Sevoflurane
    DOI:  https://doi.org/10.1016/j.intimp.2023.111210
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