bims-auttor Biomed News
on Autophagy and mTOR
Issue of 2023‒08‒20
sixty-nine papers selected by
Viktor Korolchuk, Newcastle University
  1. Emerging autophagic endo-lysosomal targets in the management of Parkinson's disease.
  2. SPART links autophagy machinery and lipid droplets in motor neurons.
  3. Optineurin tunes outside-in signaling to regulate lysosome biogenesis and phagocytic clearance in the retina.
  4. Post-translational modifications of ATG8 proteins - an emerging mechanism of autophagy control.
  5. TRPML3/BK complex promotes autophagy and bacterial clearance by providing a positive feedback regulation of mTOR via PI3P.
  6. Targeting autophagy with small-molecule activators for potential therapeutic purposes.
  7. Monitoring Lysosome Function in Ferroptosis.
  8. Ubiquitination in the regulation of autophagy.
  9. Role of lysosomes in HSV-induced pathogenesis.
  10. Interplay of energy metabolism and autophagy.
  11. Regulation of autophagy in chick myotube cultures: Effect of uncoupling mitochondrial oxidative phosphorylation.
  12. mTOR pathway - a potential therapeutic target in stroke.
  13. Tubular lysosome induction couples animal starvation to healthy aging.
  14. Phagophore closure, autophagosome maturation and autophagosome fusion during macroautophagy in the yeast Saccharomyces cerevisiae.
  15. A sweet way to regulate cellular growth: OGT and mTOR join forces.
  16. Autophagy and exercise: current insights and future research directions.
  17. Inhibition of CysLTR1 reduces the levels of aggregated proteins in retinal pigment epithelial cells.
  18. Structural mechanisms of the mTOR pathway.
  19. AutophagyNet: high-resolution data source for the analysis of autophagy and its regulation.
  20. Autophagy contributes to positive feedback regulation of SnRK1 signaling in plants.
  21. E2F1-driven histone demethylase KDM6B enhances thyroid malignancy via manipulating TFEB-dependent autophagy axis.
  22. Balancing lysosome abundance in health and disease.
  23. Protein interaction network analysis of mTOR signaling reveals modular organization.
  24. Exo84c interacts with VAP27 to regulate exocytotic compartment degradation and stigma senescence.
  25. Enhanced activation of mechanistic target of rapamycin complex 1 signaling in eruptive xanthomas.
  26. Chaperone-mediated autophagy in neuronal dendrites utilizes activity-dependent lysosomal exocytosis for protein disposal.
  27. When mitophagy dictates the outcome of cellular infection: the case of Brucella abortus.
  28. Second-Generation AUTACs for Targeted Autophagic Degradation.
  29. FAM120A couples SREBP-dependent transcription and splicing of lipogenesis enzymes downstream of mTORC1.
  30. Accumulation of F-actin drives brain aging and limits healthspan in Drosophila.
  31. The Hippo pathway noncanonically drives autophagy and cell survival in response to energy stress.
  32. [Based on the Hippo signaling pathway to explore the mechanism of autophagy in lung injury of acute respiratory distress syndrome induced by sepsis].
  33. Mitochondria are secreted in extracellular vesicles when lysosomal function is impaired.
  34. Evolutionary analysis of the mTOR pathway provide insights into lifespan extension across mammals.
  35. Pepino mosaic virus antagonizes plant m6A modification by promoting the autophagic degradation of the m6A writer HAKAI.
  36. Age-related deficits in retinal autophagy following intraocular pressure elevation in autophagy reporter mouse model.
  37. The mitophagy pathway and its implications in human diseases.
  38. Host nutrient sensing is mediated by mTOR signaling in cnidarian-dinoflagellate symbiosis.
  39. Prohibitin2/PHB2, Transcriptionally Regulated by GABPA, Inhibits Cell Growth via PRKN/Parkin-dependent Mitophagy in Endometriosis.
  40. The autophagy machinery interacts with EBV capsids during viral envelope release.
  41. Autophagy ablation in skeletal muscles worsens sepsis-induced muscle wasting, impairs whole-body metabolism, and decreases survival.
  42. Autophagy in intestinal epithelial cells prevents gut inflammation.
  43. LHPP-mediated inorganic pyrophosphate hydrolysis-driven lysosomal acidification in astrocytes regulates adult neurogenesis.
  44. Autophagy impairment and lifespan reduction caused by Atg1 RNAi or Atg18 RNAi expression in adult fruit flies (Drosophila melanogaster).
  45. Differential Regulation of Autophagy on Urine-Concentrating Capability through Modulating the Renal AQP2 Expression and Renin-Angiotensin System in Mice.
  46. YAP governs cellular adaptation to perturbation of glutamine metabolism by regulating ATF4-mediated stress response.
  47. Oleoylethanolamide facilitates PPARα and TFEB signaling and attenuates Aβ pathology in a mouse model of Alzheimer's disease.
  48. Enhanced Mitophagy in Cholesteatoma Epithelial Cells.
  49. Quantitative proteomics and phosphoproteomics of PP2A-PPP2R5D variants reveal deregulation of RPS6 phosphorylation via converging signaling cascades.
  50. Autophagy-related lncRNAs in tumor progression and drug resistance: A double-edged sword.
  51. Proteomic Investigation of Differential Interactomes of Glypican 1 and a Putative Disease-Modifying Variant of Ataxia.
  52. NCoR1 controls Mycobacterium tuberculosis growth in myeloid cells by regulating the AMPK-mTOR-TFEB axis.
  53. FGF-18 Protects the Injured Spinal cord in mice by Suppressing Pyroptosis and Promoting Autophagy via the AKT-mTOR-TRPML1 axis.
  54. Propranolol reduces the accumulation of cytotoxic aggregates in C9orf72-ALS/FTD in vitro models.
  55. ApoE4 exacerbates the senescence of hippocampal neurons and spatial cognitive impairment by downregulating acetyl-CoA level.
  56. The ubiquitin-like modifier FAT10 covalently modifies HUWE1 and strengthens the interaction of AMBRA1 and HUWE1.
  57. Cezanne promoted autophagy through PIK3C3 stabilization and PIK3C2A transcription in lung adenocarcinoma.
  58. Decreased syntaxin17 expression contributes to the pathogenesis of acute pancreatitis in murine models by impairing autophagic degradation.
  59. CCT and Cullin1 regulate the TORC1 pathway to promote dendritic arborization in health and disease.
  60. Presenilins and mitochondria-an intriguing link: mini-review.
  61. Orexin-A/OX1R is involved in regulation of autophagy to promote cortisol secretion in adrenocortical cell.
  62. Temporal control of contact site formation reveals a relationship between mitochondrial division and Num1-mediated mitochondrial tethering.
  63. Lysosomal release of amino acids at ER three-way junctions regulates transmembrane and secretory protein mRNA translation.
  64. Enhancing autophagy in CD11c+ antigen-presenting cells as a therapeutic strategy for acute respiratory distress syndrome.
  65. Lithium prevents glucocorticoid‑induced chondrocyte autophagy: An in vitro study.
  66. E4 ubiquitin ligase promotes mitofusin turnover and mitochondrial stress response.
  67. Molecular regulation of autophagy and suppression of protein kinases by aescin, a triterpenoid saponin impedes lung cancer cell proliferation and mobility.
  68. Cuproptosis enhances docetaxel chemosensitivity by inhibiting autophagy via the DLAT/mTOR pathway in prostate cancer.
  69. AMBRA1 phosphorylation by CDK1 and PLK1 regulates mitotic spindle orientation.
  1. Rev Neurol (Paris). 2023 Aug 14. pii: S0035-3787(23)00996-7. [Epub ahead of print]
    Emerging autophagic endo-lysosomal targets in the management of Parkinson's disease.
    T Siddiqui, L K Bhatt.
      Synucleopathies, specifically Parkinson's disease, are still incurable and available therapeutic options are scarce and symptomatic. The autophagy-lysosomal-endosomal system is an indigenous mechanism to manage the proteome. Excess/misfolded protein accumulation activates this system, which degrades the undesired proteins via lysosomes. Cells also eliminate these proteins by releasing them into the extracellular space via exosomes. However, the sutophagy-lysosomal-endosomal system becomes unfunctional in Parkinson's disease and there is accumulation and spread of pathogenic alpha-synuclein. Neuronal degeneration results Owing to pathogenic alpha-synuclein. Thus, the autophagy-lysosomal-endosomal system could be a promising target for neuroprotection. In the present review, we discuss the autophagy-lysosomal-endosomal system as an emerging target for the management of Parkinson's disease. Modulation of these targets associated with the autophagy-lysosomal-endosomal system can aid in clearing pathogenic alpha-synuclein and prevent the degeneration of neurons.
    Keywords:  Alpha-synuclein; Autophagy; Endo-lysosomal system; Parkinson's disease
    DOI:  https://doi.org/10.1016/j.neurol.2023.07.007
  2. Autophagy. 2023 Aug 13.
    SPART links autophagy machinery and lipid droplets in motor neurons.
    Shree Padma Metur, Daniel J Klionsky.
      Autophagy, in the form of lipophagy, is an important catabolic pathway mediating the degradation of lipid droplets and mobilization of lipids for physiological function. However, the molecular mechanism and the protein receptors that link lipid droplets/LDs to the autophagy machinery remain unknown. Here, we discuss a recent study by Chung et al. that identifies SPART as the receptor for autophagy of lipid droplets that plays an important role in the turnover of triglycerides in motor neurons.
    Keywords:  Lipid turnover; lysosome; neurobiology; spartin; stress
    DOI:  https://doi.org/10.1080/15548627.2023.2247311
  3. Curr Biol. 2023 Aug 10. pii: S0960-9822(23)00970-3. [Epub ahead of print]
    Optineurin tunes outside-in signaling to regulate lysosome biogenesis and phagocytic clearance in the retina.
    Li Xuan Tan, Colin J Germer, Thushara Thamban, Nilsa La Cunza, Aparna Lakkaraju.
      Balancing the competing demands of phagolysosomal degradation and autophagy is a significant challenge for phagocytic tissues. Yet how this plasticity is accomplished in health and disease is poorly understood. In the retina, circadian phagocytosis and degradation of photoreceptor outer segments by the postmitotic retinal pigment epithelium (RPE) are essential for healthy vision. Disrupted autophagy due to mechanistic target of rapamycin (mTOR) overactivation in the RPE is associated with blinding macular degenerations; however, outer segment degradation is unaffected in these diseases, indicating that distinct mechanisms regulate these clearance mechanisms. Here, using advanced imaging and mouse models, we identify optineurin as a key regulator that tunes phagocytosis and lysosomal capacity to meet circadian demands and helps prioritize outer segment clearance by the RPE in macular degenerations. High-resolution live-cell imaging implicates optineurin in scissioning outer segment tips prior to engulfment, analogous to microglial trogocytosis of neuronal processes. Optineurin is essential for recruiting light chain 3 (LC3), which anchors outer segment phagosomes to microtubules and facilitates phagosome maturation and fusion with lysosomes. This dynamically activates transcription factor EB (TFEB) to induce lysosome biogenesis in an mTOR-independent, transient receptor potential-mucolipin 1 (TRPML1)-dependent manner. RNA-seq analyses show that expression of TFEB target genes temporally tracks with optineurin recruitment and that lysosomal and autophagy genes are controlled by distinct transcriptional programs in the RPE. The unconventional plasma membrane-to-nucleus signaling mediated by optineurin ensures outer segment degradation under conditions of impaired autophagy in macular degeneration models. Independent regulation of these critical clearance mechanisms would help safeguard the metabolic fitness of the RPE throughout the organismal lifespan.
    Keywords:  TFEB; TRPML1; lysosomes; macular degeneration; phagocytosis; photoreceptors; retinal pigment epithelium; trogocytosis
    DOI:  https://doi.org/10.1016/j.cub.2023.07.031
  4. J Cell Sci. 2023 Aug 15. pii: jcs259725. [Epub ahead of print]136(16):
    Post-translational modifications of ATG8 proteins - an emerging mechanism of autophagy control.
    Jose L Nieto-Torres, Sviatlana Zaretski, Tianhui Liu, Peter D Adams, Malene Hansen.
      Autophagy is a recycling mechanism involved in cellular homeostasis with key implications for health and disease. The conjugation of the ATG8 family proteins, which includes LC3B (also known as MAP1LC3B), to autophagosome membranes, constitutes a hallmark of the canonical autophagy process. After ATG8 proteins are conjugated to the autophagosome membranes via lipidation, they orchestrate a plethora of protein-protein interactions that support key steps of the autophagy process. These include binding to cargo receptors to allow cargo recruitment, association with proteins implicated in autophagosome transport and autophagosome-lysosome fusion. How these diverse and critical protein-protein interactions are regulated is still not well understood. Recent reports have highlighted crucial roles for post-translational modifications of ATG8 proteins in the regulation of ATG8 functions and the autophagy process. This Review summarizes the main post-translational regulatory events discovered to date to influence the autophagy process, mostly described in mammalian cells, including ubiquitylation, acetylation, lipidation and phosphorylation, as well as their known contributions to the autophagy process, physiology and disease.
    Keywords:  ATG8; Autophagy; GABARAP; LC3; Phosphorylation; Post-translational modifications
    DOI:  https://doi.org/10.1242/jcs.259725
  5. Proc Natl Acad Sci U S A. 2023 Aug 22. 120(34): e2215777120
    TRPML3/BK complex promotes autophagy and bacterial clearance by providing a positive feedback regulation of mTOR via PI3P.
    Mengnan Xu, Xi Zoë Zhong, Peng Huang, Dawid Jaślan, Pingping Wang, Xue Sun, Eva-Maria Weiden, Yassine El Hiani, Christian Grimm, Xian-Ping Dong.
      TRPML3 is a Ca2+/Na+ release channel residing in both phagophores and endolysosomal membranes. It is activated by PI3P and PI3,5P2. Its activity can be enhanced by high luminal pH and by replacing luminal Na+ with K+. Here, we report that big-conductance Ca2+-activated potassium (BK) channels form a positive feedback loop with TRPML3. Ca2+ release via TRPML3 activates BK, which in turn facilitates TRPML3-mediated Ca2+ release, potentially through removing luminal Na+ inhibition. We further show that TRPML3/BK and mammalian target of rapamycin (mTOR) form another positive feedback loop to facilitate autophagy induction in response to nutrient starvation, i.e., mTOR inhibition upon nutrient starvation activates TRPML3/BK, and this further reduces mTOR activity, thereby increasing autophagy induction. Mechanistically, the feedback regulation between TRPML3/BK and mTOR is mediated by PI3P, an endogenous TRPML3 activator that is enriched in phagophores and is up-regulated by mTOR reduction. Importantly, bacterial infection activates TRPML3 in a BK-dependent manner, and both TRPML3 and BK are required for mTOR suppression and autophagy induction responding to bacterial infection. Suppressing either TRPML3 or BK helps bacteria survival whereas increasing either TRPML3 or BK favors bacterial clearance. Considering that TRPML3/BK is inhibited by low luminal pH but activated by high luminal pH and PI3P in phagophores, we suggest that TRPML3/BK and mTOR form a positive feedback loop via PI3P to ensure efficient autophagy induction in response to nutrient deprivation and bacterial infection. Our study reveals a role of TRPML3-BK coupling in controlling cellular homeostasis and intracellular bacterial clearance via regulating mTOR signaling.
    Keywords:  TRPML3; autophagy; endolysosome; mTOR
    DOI:  https://doi.org/10.1073/pnas.2215777120
  6. Eur J Med Chem. 2023 Aug 12. pii: S0223-5234(23)00689-X. [Epub ahead of print]260 115722
    Targeting autophagy with small-molecule activators for potential therapeutic purposes.
    Zhichao Fan, Lin-Xi Wan, Wei Jiang, Bo Liu, Dongbo Wu.
      Autophagy is well-known to be a lysosome-mediated catabolic process for maintaining cellular and organismal homeostasis, which has been established with many links to a variety of human diseases. Compared with the therapeutic strategy for inhibiting autophagy, activating autophagy seems to be another promising therapeutic strategy in several contexts. Hitherto, mounting efforts have been made to discover potent and selective small-molecule activators of autophagy to potentially treat human diseases. Thus, in this perspective, we focus on summarizing the complicated relationships between defective autophagy and human diseases, and further discuss the updated progress of a series of small-molecule activators targeting autophagy in human diseases. Taken together, these inspiring findings would provide a clue on discovering more small-molecule activators of autophagy as targeted candidate drugs for potential therapeutic purposes.
    Keywords:  Autophagic target; Autophagy; Candidate drug; Human disease; Small-molecule activator
    DOI:  https://doi.org/10.1016/j.ejmech.2023.115722
  7. Methods Mol Biol. 2023 ;2712 91-102
    Monitoring Lysosome Function in Ferroptosis.
    Fangquan Chen, Rui Kang, Daolin Tang, Jiao Liu.
      Ferroptosis is a type of regulated cell death that occurs due to iron-induced membrane lipid peroxidation. Lysosomes, which are acidic, membrane-bound organelles containing various hydrolases, play a vital role in ferroptosis. They not only aid in the degradation of autophagic substrates, but also serve as signaling hubs in cell death. Specifically, lysosomes are involved in the induction and execution of ferroptosis through autophagy-mediated degradation of anti-ferroptotic proteins, lysosomal membrane permeability-mediated release of cathepsins, and iron-induced lysosomal membrane lipid peroxidation. Therefore, it is essential to have reliable methods for monitoring lysosomal functions, including lysosomal activity, pH, and membrane integrity, as well as iron accumulation and lipid peroxidation, to understand ferroptosis. This chapter introduces several protocols, such as western blotting, immunofluorescence, lysosomal probes, and lipid peroxidation assay kits, for monitoring the process of lysosome-related ferroptosis.
    Keywords:  Autophagy; Cell death; Ferroptosis; Lysosome
    DOI:  https://doi.org/10.1007/978-1-0716-3433-2_9
  8. Acta Biochim Biophys Sin (Shanghai). 2023 Aug 16.
    Ubiquitination in the regulation of autophagy.
    Xueyan Cen, Ziling Li, Xinpeng Chen.
      Autophagy, an efficient and effective approach to clear rapidly damaged organelles, macromolecules, and other harmful cellular components, enables the recycling of nutrient materials and supply of nutrients to maintain cellular homeostasis. Ubiquitination plays an important regulatory role in autophagy. This paper summarizes the most recent progress in ubiquitin modification in various stages of autophagy, including initiation, elongation, and termination. Moreover, this paper shows that ubiquitination is an important way through which selective autophagy achieves substrate specificity. Furthermore, we note the distinction between monoubiquitination and polyubiquitination in the regulation of autophagy. Compared with monoubiquitination, polyubiquitination is a more common strategy to regulate the activity of the autophagy molecular machinery. In addition, the role of ubiquitination in the closure and fusion of autophagosomes warrants further study. This article not only clarifies the regulatory mechanism of autophagy but also contributes to a deeper understanding of the importance of ubiquitination modification.
    Keywords:  autophagy molecule machine; monoubiquitination; polyubiquitination; selective autophagy
    DOI:  https://doi.org/10.3724/abbs.2023149
  9. Future Microbiol. 2023 Aug 16.
    Role of lysosomes in HSV-induced pathogenesis.
    Jieqiong Ding, Liqiong Ding.
      HSV can evade host defenses and cause lifelong infection and severe illness. Lysosomes are catabolic organelles that play an important role in the regulation of cellular homeostasis. Lysosomal dysfunction and alterations in the process of autophagy have been identified in a variety of diseases, including HSV infection, and targeting lysosomes is a potential anti-HSV therapeutic strategy. This article reviews the role of lysosomes and lysosome-associated proteins in HSV infection, providing attractive targets and novel strategies for the treatment of HSV infection.
    Keywords:  HSV; autophagy; hydrolases; lysosome; lysosome-associated membrane glycoproteins
    DOI:  https://doi.org/10.2217/fmb-2023-0090
  10. Autophagy. 2023 Aug 18. 1-11
    Interplay of energy metabolism and autophagy.
    Yuyao Feng, Ying Chen, Xiaoyong Wu, Junye Chen, Qingyan Zhou, Bao Liu, Liqin Zhang, Cong Yi.
      Macroautophagy/autophagy, is widely recognized for its crucial role in enabling cell survival and maintaining cellular energy homeostasis during starvation or energy stress. Its regulation is intricately linked to cellular energy status. In this review, covering yeast, mammals, and plants, we aim to provide a comprehensive overview of the understanding of the roles and mechanisms of carbon- or glucose-deprivation related autophagy, showing how cells effectively respond to such challenges for survival. Further investigation is needed to determine the specific degraded substrates by autophagy during glucose or energy deprivation and the diverse roles and mechanisms during varying durations of energy starvation.Abbreviations: ADP: adenosine diphosphate; AMP: adenosine monophosphate; AMPK: AMP-activated protein kinase; ATG: autophagy related; ATP: adenosine triphosphate; ER: endoplasmic reticulum; ESCRT: endosomal sorting complex required for transport; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GD: glucose deprivation; GFP: green fluorescent protein; GTPases: guanosine triphosphatases; HK2: hexokinase 2; K phaffii: Komagataella phaffii; LD: lipid droplet; MAP1LC3/LC3: microtubule-associated protein1 light chain 3; MAPK: mitogen-activated protein kinase; Mec1: mitosis entry checkpoint 1; MTOR: mechanistic target of rapamycin kinase; NAD (+): nicotinamide adenine dinucleotide; OGD: oxygen and glucose deprivation; PAS: phagophore assembly site; PCD: programmed cell death; PtdIns3K: class III phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol-3-phosphate; ROS: reactive oxygen species; S. cerevisiae: Saccharomyces cerevisiae; SIRT1: sirtuin 1; Snf1: sucrose non-fermenting 1; STK11/LKB1: serine/threonine kinase 11; TFEB: transcription factor EB; TORC1: target of rapamycin complex 1; ULK1: unc-51 like kinase 1; Vps27: vacuolar protein sorting 27; Vps4: vacuolar protein sorting 4.
    Keywords:  AMPK; Snf1; autophagy; carbon starvation; energy metabolism; glucose starvation
    DOI:  https://doi.org/10.1080/15548627.2023.2247300
  11. J Poult Sci. 2023 ;60 2023022
    Regulation of autophagy in chick myotube cultures: Effect of uncoupling mitochondrial oxidative phosphorylation.
    Kazuki Nakashima, Aiko Ishida.
      Abstracts: Skeletal muscles have a high demand for ATP, which is met largely through mitochondria oxidative phosphorylation. Autophagy is essential for the maintenance of skeletal muscle mass under catabolic conditions. This study investigated the effect of uncoupling mitochondrial oxidative phosphorylation on autophagy in chicken skeletal muscle. Chick myotubes were incubated with the mitochondrial uncoupler carbonyl cyanide m-chlorophenyl hydrazone (CCCP) at 25 μM for 3h. CCCP prevented the phosphorylation of p70 ribosomal S6 kinase 1 (Thr389), S6 ribosomal protein (Ser240/244), and eukaryotic translation initiation factor 4E-binding protein 1 (Thr37/46), which are the measures of the mechanistic target of rapamycin complex 1 (mTORC1) activity. CCCP significantly increased cytoplasmic and mitochondrial LC3-II content, which act as indices of index for autophagosome formation and mitophagy, respectively, but did not influence the expression of autophagy-related genes LC3B, GABARAPL1, and ATG12. Finally, surface sensing of translation method revealed that protein synthesis, a highly energy consuming process, was significantly decreased upon CCCP treatment. These results indicate that the uncoupling of mitochondrial oxidative phosphorylation stimulates autophagy and inhibits protein synthesis through mTORC1 signaling in chick myotube cultures.
    Keywords:  autophagy; carbonyl cyanide m-chlorophenyl hydrazone (CCCP); chick myotubes; mitophagy; protein synthesis
    DOI:  https://doi.org/10.2141/jpsa.2023022
  12. Ther Adv Neurol Disord. 2023 ;16 17562864231187770
    mTOR pathway - a potential therapeutic target in stroke.
    Konstantinos Melanis, Maria-Ioanna Stefanou, Konstantinos M Themistoklis, Themistoklis Papasilekas.
      Stroke is ranked as the second leading cause of death worldwide and a major cause of long-term disability. A potential therapeutic target that could offer favorable outcomes in stroke is the mammalian target of rapamycin (mTOR) pathway. mTOR is a serine/threonine kinase that composes two protein complexes, mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2), and is regulated by other proteins such as the tuberous sclerosis complex. Through a significant number of signaling pathways, the mTOR pathway can modulate the processes of post-ischemic inflammation and autophagy, both of which play an integral part in the pathophysiological cascade of stroke. Promoting or inhibiting such processes under ischemic conditions can lead to apoptosis or instead sustained viability of neurons. The purpose of this review is to examine the pathophysiological role of mTOR in acute ischemic stroke, while highlighting promising neuroprotective agents such as hamartin for therapeutic modulation of this pathway. The therapeutic potential of mTOR is also discussed, with emphasis on implicated molecules and pathway steps that warrant further elucidation in order for their neuroprotective properties to be efficiently tested in future clinical trials.
    Keywords:  mTOR pathway; neuroprotection; stroke; tuberous sclerosis complex
    DOI:  https://doi.org/10.1177/17562864231187770
  13. Nat Aging. 2023 Aug 14.
    Tubular lysosome induction couples animal starvation to healthy aging.
    Tatiana V Villalobos, Bhaswati Ghosh, Kathryn R DeLeo, Sanaa Alam, Cristian Ricaurte-Perez, Andrew Wang, Brennan M Mercola, Tyler J Butsch, Cara D Ramos, Suman Das, Eric D Eymard, K Adam Bohnert, Alyssa E Johnson.
      Dietary restriction promotes longevity in several species via autophagy activation. However, changes to lysosomes underlying this effect remain unclear. Here using the nematode Caenorhabditis elegans, we show that the induction of autophagic tubular lysosomes (TLs), which occurs upon dietary restriction or mechanistic target of rapamycin inhibition, is a critical event linking reduced food intake to lifespan extension. We find that starvation induces TLs not only in affected individuals but also in well-fed descendants, and the presence of gut TLs in well-fed progeny is predictive of enhanced lifespan. Furthermore, we demonstrate that expression of Drosophila small VCP-interacting protein, a TL activator in flies, artificially induces TLs in well-fed worms and improves C. elegans health in old age. These findings identify TLs as a new class of lysosomes that couples starvation to healthy aging.
    DOI:  https://doi.org/10.1038/s43587-023-00470-6
  14. FEBS Lett. 2023 Aug 16.
    Phagophore closure, autophagosome maturation and autophagosome fusion during macroautophagy in the yeast Saccharomyces cerevisiae.
    Claudine Kraft, Fulvio Reggiori.
      Macroautophagy, hereafter referred to as autophagy, is a complex process in which multiple membrane-remodeling events lead to the formation of a cisterna known as the phagophore, which then expands and closes into a double-membrane vesicle termed the autophagosome. During the past decade, enormous progress has been made in understanding the molecular function of the autophagy-related proteins and their role in generating these phagophores. In this Review, we discuss the current understanding of three membrane remodeling steps in autophagy that remain to be largely characterized; namely, the closure of phagophores, the maturation of the resulting autophagosomes into fusion-competent vesicles, and their fusion with vacuoles/lysosomes. Our review will mainly focus on the yeast Saccharomyces cerevisiae, which has been the leading model system for the study of molecular events in autophagy and has led to the discovery of the major mechanistic concepts, which have been found to be mostly conserved in higher eukaryotes.
    Keywords:  Atg proteins; Autophagy; PAS; dephosphorylation; phagophore
    DOI:  https://doi.org/10.1002/1873-3468.14720
  15. Mol Cell. 2023 Aug 17. pii: S1097-2765(23)00559-2. [Epub ahead of print]83(16): 2832-2833
    A sweet way to regulate cellular growth: OGT and mTOR join forces.
    Pedro Latorre-Muro, Pere Puigserver.
      In this issue, Xu and Pan et al1 report a glucose-sensing and activation mechanism of mTORC1 through the glycosyltransferase OGT, which activates Raptor, allowing lysosomal targeting of mTORC1 to promote cell proliferation.
    DOI:  https://doi.org/10.1016/j.molcel.2023.07.016
  16. Int J Sports Med. 2023 Aug 15.
    Autophagy and exercise: current insights and future research directions.
    Javier Botella, Chris Shaw, David Bishop.
      Autophagy is a cellular process by which proteins and organelles are degraded inside the lysosome. Exercise is known to influence the regulation of autophagy in skeletal muscle. However, as gold standard techniques to assess autophagy flux in vivo are restricted to animal research, important gaps remain in our understanding of how exercise influences autophagy activity in humans. Using available datasets, we show how the gene expression profile of autophagy receptors and ATG8 family members differ between human and mouse skeletal muscle, providing a potential explanation for their differing exercise-induced autophagy responses. Furthermore, we provide a comprehensive view of autophagy regulation following exercise in humans by summarising human transcriptomic and phosphoproteomic datasets that provide novel targets of potential relevance. These newly identified phosphorylation sites may provide an explanation as to why both endurance and resistance exercise lead to an exercise-induced reduction in LC3B-II, while possibly divergently regulating autophagy receptors, and, potentially, autophagy flux. We also provide recommendations to use ex vivo autophagy flux assays to better understand the influence of exercise, and other stimuli, on autophagy regulation in humans. This review provides a critical overview of the field and points towards novel research areas of autophagy regulation following exercise in humans.
    DOI:  https://doi.org/10.1055/a-2153-9258
  17. Sci Rep. 2023 08 14. 13(1): 13239
    Inhibition of CysLTR1 reduces the levels of aggregated proteins in retinal pigment epithelial cells.
    Andreas Koller, Susanne Maria Brunner, Julia Preishuber-Pflügl, Daniela Mayr, Anja-Maria Ladek, Christian Runge, Herbert Anton Reitsamer, Andrea Trost.
      The endosomal-lysosomal system (ELS), which carries out cellular processes such as cellular waste degradation via autophagy, is essential for cell homeostasis. ELS inefficiency leads to augmented levels of damaged organelles and intracellular deposits. Consequently, the modulation of autophagic flux has been recognized as target to remove damaging cell waste. Recently, we showed that cysteinyl leukotriene receptor 1 (CysLTR1) antagonist application increases the autophagic flux in the retinal pigment epithelial cell line ARPE-19. Consequently, we investigated the effect of CysLTR1 inhibition-driven autophagy induction on aggregated proteins in ARPE-19 cells using flow cytometry analysis. A subset of ARPE-19 cells expressed CysLTR1 on the surface (SE+); these cells showed increased levels of autophagosomes, late endosomes/lysosomes, aggregated proteins, and autophagy as well as decreased reactive oxygen species (ROS) formation. Furthermore, CysLTR1 inhibition for 24 h using the antagonist zafirlukast decreased the quantities of autophagosomes, late endosomes/lysosomes, aggregated proteins and ROS in CysLTR1 SE- and SE+ cells. We concluded that high levels of plasma membrane-localized CysLTR1 indicate an increased amount of aggregated protein, which raises the rate of autophagic flux. Furthermore, CysLTR1 antagonist application potentially mimics the physiological conditions observed in CysLTR1 SE+ cells and can be considered as strategy to dampen cellular aging.
    DOI:  https://doi.org/10.1038/s41598-023-40248-9
  18. Curr Opin Struct Biol. 2023 Aug 10. pii: S0959-440X(23)00137-9. [Epub ahead of print]82 102663
    Structural mechanisms of the mTOR pathway.
    Karen Y Linde-Garelli, Kacper B Rogala.
      The mTOR signaling pathway is essential for regulating cell growth and mammalian metabolism. The mTOR kinase forms two complexes, mTORC1 and mTORC2, which respond to external stimuli and regulate differential downstream targets. Cellular membrane-associated translocation mediates function and assembly of the mTOR complexes, and recent structural studies have begun uncovering the molecular basis by which the mTOR pathway (1) regulates signaling inputs, (2) recruits substrates, (3) localizes to biological membranes, and (4) becomes activated. Moreover, indications of dysregulated mTOR signaling are implicated in a wide range of diseases and an increasingly comprehensive understanding of structural mechanisms is driving novel translational development.
    DOI:  https://doi.org/10.1016/j.sbi.2023.102663
  19. Autophagy. 2023 Aug 17. 1-15
    AutophagyNet: high-resolution data source for the analysis of autophagy and its regulation.
    Luca Csabai, Balázs Bohár, Dénes Türei, Sowmya Prabhu, László Földvári-Nagy, Matthew Madgwick, Dávid Fazekas, Dezső Módos, Márton Ölbei, Themis Halka, Martina Poletti, Polina Kornilova, Tamás Kadlecsik, Amanda Demeter, Máté Szalay-Bekő, Orsolya Kapuy, Katalin Lenti, Tibor Vellai, Lejla Gul, Tamás Korcsmáros.
      Macroautophagy/autophagy is a highly-conserved catabolic procss eliminating dysfunctional cellular components and invading pathogens. Autophagy malfunction contributes to disorders such as cancer, neurodegenerative and inflammatory diseases. Understanding autophagy regulation in health and disease has been the focus of the last decades. We previously provided an integrated database for autophagy research, the Autophagy Regulatory Network (ARN). For the last eight years, this resource has been used by thousands of users. Here, we present a new and upgraded resource, AutophagyNet. It builds on the previous database but contains major improvements to address user feedback and novel needs due to the advancement in omics data availability. AutophagyNet contains updated interaction curation and integration of over 280,000 experimentally verified interactions between core autophagy proteins and their protein, transcriptional and post-transcriptional regulators as well as their potential upstream pathway connections. AutophagyNet provides annotations for each core protein about their role: 1) in different types of autophagy (mitophagy, xenophagy, etc.); 2) in distinct stages of autophagy (initiation, expansion, termination, etc.); 3) with subcellular and tissue-specific localization. These annotations can be used to filter the dataset, providing customizable download options tailored to the user's needs. The resource is available in various file formats (e.g. CSV, BioPAX and PSI-MI), and data can be analyzed and visualized directly in Cytoscape. The multi-layered regulation of autophagy can be analyzed by combining AutophagyNet with tissue- or cell type-specific (multi-)omics datasets (e.g. transcriptomic or proteomic data). The resource is publicly accessible at http://autophagynet.org.Abbreviations: ARN: Autophagy Regulatory Network; ATG: autophagy related; BCR: B cell receptor pathway; BECN1: beclin 1; GABARAP: GABA type A receptor-associated protein; IIP: innate immune pathway; LIR: LC3-interacting region; lncRNA: long non-coding RNA; MAP1LC3B: microtubule associated protein 1 light chain 3 beta; miRNA: microRNA; NHR: nuclear hormone receptor; PTM: post-translational modification; RTK: receptor tyrosine kinase; TCR: T cell receptor; TLR: toll like receptor.
    Keywords:  Autophagy regulation; big data; multi-omics; network resource; signaling
    DOI:  https://doi.org/10.1080/15548627.2023.2247737
  20. Autophagy. 2023 Aug 16.
    Autophagy contributes to positive feedback regulation of SnRK1 signaling in plants.
    Chao Yang, Xibao Li, Jun Zhou, Caiji Gao.
      SnRK1 (SNF1-related protein kinase 1) is a plant ortholog of yeast Snf1 and mammalian adenosine monophosphate-activated protein kinase (AMPK) that acts as a positive regulator of macroautophagy/autophagy. However, whether and how the autophagy pathway modulates SnRK1 activity remains elusive. Recently, we identified a clade of plant-specific FLZ (FCS-like zinc finger) proteins as novel ATG8 (autophagy related 8)-interacting partners in Arabidopsis thaliana. These AtFLZs, which mainly localize on the surface of mitochondria, can inhibit SnRK1 signaling by repressing the T-loop phosphorylation of its catalytic α subunits, thereby negatively regulating carbon starvation-induced autophagy and plant tolerance to energy deprivation. Upon energy starvation, autophagy is activated to mediate the degradation of these AtFLZs, thus relieving their repression of SnRK1. More importantly, the ATG8-FLZ-SnRK1 regulatory axis appears to be functionally conserved during seed plant evolution. These findings highlight the positive role of autophagy in SnRK1 signaling activation under energy-limiting conditions in plants.
    Keywords:  ATG8; FLZ; SnRK1; autophagy; carbon starvation
    DOI:  https://doi.org/10.1080/15548627.2023.2247741
  21. Exp Cell Res. 2023 Aug 11. pii: S0014-4827(23)00290-2. [Epub ahead of print] 113742
    E2F1-driven histone demethylase KDM6B enhances thyroid malignancy via manipulating TFEB-dependent autophagy axis.
    Xiaoyuan Wang, Chi Zhang, Na Dong, Hai'e Xu, Yi Zhou, Dawei Hou.
      Aberrant epigenetic modifications or events regulate autophagy to influence tumor progression, which has gained increasing attention. KDM6B is an essential histone demethylase that participates in multiple processes of tumors, but its role in thyroid carcinoma (THCA) remains to be unknown. Here, in this study, we used the MTT assay to screen and validate that KDM6B is an essential demethylase for THCA. KDM6B promotes THCA proliferation, migration, invasion in vitro and in vivo. Transcriptional factor E2F1 directly binds to the promoter region of KDM6B and regulates its mRNA levels in THCA. E2F1 partially depended on KDM6B to exert its oncogenic functions. Mechanistically, KDM6B binds to TFEB promoter region and mediates the demethylation of H3K27me3. KDM6B depended on TFEB to activate a series of lysosomal-related genes. KDM6B enhances autophagy process, as evidenced by elevated p62 and Beclin-1 proteins. KDM6B depended on TFEB-driven autophagy activity to accelerate THCA progression. Lastly, targeting autophagy with 3-MA could notably abrogate growth of KDM6Bhigh THCA, but has mild influence on KDM6Blow THCA. Together, this study identified KDM6B as an essential epigenetic regulator for THCA, functioning as an autophagy regulator. The fundamental mechanisms underlying E2F1/KDM6B/TFEB axis provided novel vulnerabilities for THCA treatment.
    Keywords:  3-MA; Autophagy; KDM6B; TFEB; Thyroid carcinoma
    DOI:  https://doi.org/10.1016/j.yexcr.2023.113742
  22. Nat Cell Biol. 2023 Aug 14.
    Balancing lysosome abundance in health and disease.
    Anders P Mutvei, Michal J Nagiec, John Blenis.
      Lysosomes are catabolic organelles that govern numerous cellular processes, including macromolecule degradation, nutrient signalling and ion homeostasis. Aberrant changes in lysosome abundance are implicated in human diseases. Here we outline the mechanisms of lysosome biogenesis and turnover, and discuss how changes in the lysosome pool impact physiological and pathophysiological processes.
    DOI:  https://doi.org/10.1038/s41556-023-01197-7
  23. bioRxiv. 2023 Aug 04. pii: 2023.08.04.552011. [Epub ahead of print]
    Protein interaction network analysis of mTOR signaling reveals modular organization.
    Devin T Wehle, Carter S Bass, Josef Sulc, Ghayda Mirzaa, Stephen E P Smith.
      The mammalian target of rapamycin (mTOR) is a serine-threonine kinase that acts as a central mediator of translation, and plays important roles in cell growth, synaptic plasticity, cancer, and a wide range of developmental disorders. The signaling cascade linking lipid kinases (PI3Ks), protein kinases (AKT) and translation initiation complexes (EIFs) to mTOR has been extensively modeled, but does not fully describe mTOR system behavior. Here, we use quantitative multiplex co-immunoprecipitation to monitor a protein interaction network (PIN) composed of 300+ binary interactions among mTOR-related proteins. Using a simple model system of serum deprived or fresh-media-fed mouse 3T3 fibroblasts, we observed extensive PIN remodeling involving 27+ individual protein interactions after one hour, despite phosphorylation changes observed after only five minutes. Using small molecule inhibitors of PI3K, AKT, mTOR, MEK and ERK, we define subsets of the PIN, termed 'modules', that respond differently to each inhibitor. Using primary fibroblasts from individuals with overgrowth disorders caused by pathogenic PIK3CA or MTOR variants, we find that hyperactivation of mTOR pathway components is reflected in a hyperactive PIN. Our data define a "modular" organization of the mTOR PIN in which coordinated groups of interactions respond to activation or inhibition of distinct nodes, and demonstrate that kinase inhibitors affect the modular network architecture in a complex manner, inconsistent with simple linear models of signal transduction.
    DOI:  https://doi.org/10.1101/2023.08.04.552011
  24. Nat Commun. 2023 Aug 14. 14(1): 4888
    Exo84c interacts with VAP27 to regulate exocytotic compartment degradation and stigma senescence.
    Tong Zhang, Yifan Li, Chengyang Li, Jingze Zang, Erlin Gao, Johan T Kroon, Xiaolu Qu, Patrick J Hussey, Pengwei Wang.
      In plants, exocyst subunit isoforms exhibit significant functional diversity in that they are involved in either protein secretion or autophagy, both of which are essential for plant development and survival. Although the molecular basis of autophagy is widely reported, its contribution to plant reproduction is not very clear. Here, we have identified Exo84c, a higher plant-specific Exo84 isoform, as having a unique function in modulating exocytotic compartment degradation during stigmatic tissue senescence. This process is achieved through its interaction with the ER localised VAP27 proteins, which regulate the turnover of Exo84c through the autophagy pathway. VAP27 recruits Exo84c onto the ER membrane as well as numerous ER-derived autophagosomes that are labelled with ATG8. These Exo84c/exocyst and VAP27 positive structures are accumulated in the vacuole for degradation, and this process is partially perturbed in the exo84c knock-out mutants. Interestingly, the exo84c mutant showed a prolonged effective pollination period with higher seed sets, possibly because of the delayed stigmatic senescence when Exo84c regulated autophagy is blocked. In conclusion, our studies reveal a link between the exocyst complex and the ER network in regulating the degradation of exocytosis vesicles, a process that is essential for normal papilla cell senescence and flower receptivity.
    DOI:  https://doi.org/10.1038/s41467-023-40729-5
  25. JAAD Int. 2023 Dec;13 26-27
    Enhanced activation of mechanistic target of rapamycin complex 1 signaling in eruptive xanthomas.
    Yan Huang, Baiping Cui, Yun Bai, Juan Wang, Hanyu Dou, Yanfei Jin, Qian Du, Yongxian Lai, Yeqiang Liu, Xiaolei Ding.
      
    Keywords:  eruptive xanthoma; lipid metabolism; mTOR; mTORC1; macrophage
    DOI:  https://doi.org/10.1016/j.jdin.2023.07.001
  26. Cell Rep. 2023 Aug 16. pii: S2211-1247(23)01009-4. [Epub ahead of print]42(8): 112998
    Chaperone-mediated autophagy in neuronal dendrites utilizes activity-dependent lysosomal exocytosis for protein disposal.
    Katarzyna M Grochowska, Marit Sperveslage, Rajeev Raman, Antonio V Failla, Dawid Głów, Christian Schulze, Laura Laprell, Boris Fehse, Michael R Kreutz.
      The complex morphology of neurons poses a challenge for proteostasis because the majority of lysosomal degradation machinery is present in the cell soma. In recent years, however, mature lysosomes were identified in dendrites, and a fraction of those appear to fuse with the plasma membrane and release their content to the extracellular space. Here, we report that dendritic lysosomes are heterogeneous in their composition and that only those containing lysosome-associated membrane protein (LAMP) 2A and 2B fuse with the membrane and exhibit activity-dependent motility. Exocytotic lysosomes dock in close proximity to GluN2B-containing N-methyl-D-aspartate-receptors (NMDAR) via an association of LAMP2B to the membrane-associated guanylate kinase family member SAP102/Dlg3. NMDAR-activation decreases lysosome motility and promotes membrane fusion. We find that chaperone-mediated autophagy is a supplier of content that is released to the extracellular space via lysosome exocytosis. This mechanism enables local disposal of aggregation-prone proteins like TDP-43 and huntingtin.
    Keywords:  CMA; CP: Cell biology; CP: Neuroscience; GluN2B NMDAR; LAMP2; SAP102; dendrites; exocytosis; lysosomes
    DOI:  https://doi.org/10.1016/j.celrep.2023.112998
  27. Autophagy. 2023 Aug 17. 1-2
    When mitophagy dictates the outcome of cellular infection: the case of Brucella abortus.
    Jérémy Verbeke, Xavier De Bolle, Thierry Arnould.
      Mitochondria are at the basis of various cellular functions ranging from metabolism and redox homeostasis to inflammation and cell death regulation. Mitochondria therefore constitute an attractive target for invading pathogens to fulfil their infectious cycle. This involves the modulation to their advantage of mitochondrial metabolism and dynamics, including the controlled degradation of mitochondria through mitophagy. Mitophagy might for instance be beneficial for bacterial survival as it can clear bactericidal mitochondrial ROS produced by damaged organelle fragments from the intracellular niche. In the case of the bacterial pathogen Brucella abortus, mitophagy induction has another role in the intracellular lifecycle of the bacteria. Indeed, in our study, we showed that B. abortus triggers an iron-dependent BNIP3L-mediated mitophagy response required for proper bacterial egress and infection of neighboring cells. These results highlight the diversity of mitophagy processes that might be crucial for several stages of cellular infection.
    Keywords:  BNIP3L; Brucella; HIF1A; intracellular trafficking; iron; mitophagy
    DOI:  https://doi.org/10.1080/15548627.2023.2246354
  28. J Med Chem. 2023 Aug 17.
    Second-Generation AUTACs for Targeted Autophagic Degradation.
    Daiki Takahashi, Taiichi Ora, Shigekazu Sasaki, Naoki Ishii, Toshio Tanaka, Takumi Matsuda, Mutsuki Ikeda, Jun Moriyama, Nobuo Cho, Hiroshi Nara, Hironobu Maezaki, Masahiro Kamaura, Kenichiro Shimokawa, Hirokazu Arimoto.
      Targeted protein degradation via the ubiquitin-proteasome system has emerged as one of the most promising drug discovery modalities. Autophagy, another intracellular degradation system, can target a wide range of nonproteinous substrates as well as proteins, but its application to targeted degradation is still in its infancy. Our previous work revealed a relationship between guanine modification of cysteine residues on intracellular proteins and selective autophagy, resulting in the first autophagy-based degraders, autophagy-targeted chimeras (AUTACs). Based on the research background, all the reported AUTACs compounds contain cysteine as a substructure. Here, we examine the importance of this substructure by conducting SAR studies and report significant improvements in the degrader's activity by replacing cysteine with other moieties. Several derivatives showed sub-μM range degrading activity, demonstrating the increased practical value of AUTACs.
    DOI:  https://doi.org/10.1021/acs.jmedchem.3c00861
  29. Mol Cell. 2023 Aug 17. pii: S1097-2765(23)00560-9. [Epub ahead of print]83(16): 3010-3026.e8
    FAM120A couples SREBP-dependent transcription and splicing of lipogenesis enzymes downstream of mTORC1.
    Sungyun Cho, Yujin Chun, Long He, Cuauhtemoc B Ramirez, Kripa S Ganesh, Kyungjo Jeong, Junho Song, Jin Gyu Cheong, Zhongchi Li, Jungmin Choi, Joohwan Kim, Nikos Koundouros, Fangyuan Ding, Noah Dephoure, Cholsoon Jang, John Blenis, Gina Lee.
      The mechanistic target of rapamycin complex 1 (mTORC1) is a master regulator of cell growth that stimulates macromolecule synthesis through transcription, RNA processing, and post-translational modification of metabolic enzymes. However, the mechanisms of how mTORC1 orchestrates multiple steps of gene expression programs remain unclear. Here, we identify family with sequence similarity 120A (FAM120A) as a transcription co-activator that couples transcription and splicing of de novo lipid synthesis enzymes downstream of mTORC1-serine/arginine-rich protein kinase 2 (SRPK2) signaling. The mTORC1-activated SRPK2 phosphorylates splicing factor serine/arginine-rich splicing factor 1 (SRSF1), enhancing its binding to FAM120A. FAM120A directly interacts with a lipogenic transcription factor SREBP1 at active promoters, thereby bridging the newly transcribed lipogenic genes from RNA polymerase II to the SRSF1 and U1-70K-containing RNA-splicing machinery. This mTORC1-regulated, multi-protein complex promotes efficient splicing and stability of lipogenic transcripts, resulting in fatty acid synthesis and cancer cell proliferation. These results elucidate FAM120A as a critical transcription co-factor that connects mTORC1-dependent gene regulation programs for anabolic cell growth.
    Keywords:  FAM120A; RNA splicing; RNA stability; SREBP; SRPK2; SRSF1; lipid metabolism; mTOR signaling
    DOI:  https://doi.org/10.1016/j.molcel.2023.07.017
  30. Res Sq. 2023 Aug 01. pii: rs.3.rs-3158290. [Epub ahead of print]
    Accumulation of F-actin drives brain aging and limits healthspan in Drosophila.
    David Walker, Edward Schmid, Joseph Schinaman, Kylie Williams.
      The actin cytoskeleton is a key determinant of cell and tissue homeostasis. However, tissue-specific roles for actin dynamics in aging, notably brain aging, are not understood. Here, we show that there is an age-related increase in filamentous actin (F-actin) in Drosophila brains, which is counteracted by prolongevity interventions. Critically, modulating F-actin levels in aging neurons prevents age-onset cognitive decline and extends organismal healthspan. Mechanistically, we show that autophagy, a recycling process required for neuronal homeostasis, is disabled upon actin dysregulation in the aged brain. Remarkably, disrupting actin polymerization in aged animals with cytoskeletal drugs restores brain autophagy to youthful levels and reverses cellular hallmarks of brain aging. Finally, reducing F-actin levels in aging neurons slows brain aging and promotes healthspan in an autophagy-dependent manner. Our data identify excess actin polymerization as a hallmark of brain aging, which can be targeted to reverse brain aging phenotypes and prolong healthspan.
    DOI:  https://doi.org/10.21203/rs.3.rs-3158290/v1
  31. Mol Cell. 2023 Aug 17. pii: S1097-2765(23)00562-2. [Epub ahead of print]
    The Hippo pathway noncanonically drives autophagy and cell survival in response to energy stress.
    Gayoung Seo, Clinton Yu, Han Han, Li Xing, Rebecca Elizabeth Kattan, Jeongmin An, Amrutha Kizhedathu, Bing Yang, Annabella Luo, Abigail L Buckle, Delia Tifrea, Robert Edwards, Lan Huang, Huai-Qiang Ju, Wenqi Wang.
      The Hippo pathway is known for its crucial involvement in development, regeneration, organ size control, and cancer. While energy stress is known to activate the Hippo pathway and inhibit its effector YAP, the precise role of the Hippo pathway in energy stress response remains unclear. Here, we report a YAP-independent function of the Hippo pathway in facilitating autophagy and cell survival in response to energy stress, a process mediated by its upstream components MAP4K2 and STRIPAK. Mechanistically, energy stress disrupts the MAP4K2-STRIPAK association, leading to the activation of MAP4K2. Subsequently, MAP4K2 phosphorylates ATG8-family member LC3, thereby facilitating autophagic flux. MAP4K2 is highly expressed in head and neck cancer, and its mediated autophagy is required for head and neck tumor growth in mice. Altogether, our study unveils a noncanonical role of the Hippo pathway in energy stress response, shedding light on this key growth-related pathway in tissue homeostasis and cancer.
    Keywords:  LC3; MAP4K2; STRIPAK; autophagy; energy stress; head and neck cancer; the Hippo pathway
    DOI:  https://doi.org/10.1016/j.molcel.2023.07.019
  32. Zhonghua Wei Zhong Bing Ji Jiu Yi Xue. 2023 Aug;35(8): 884-888
    [Based on the Hippo signaling pathway to explore the mechanism of autophagy in lung injury of acute respiratory distress syndrome induced by sepsis].
    Dian Yu, Yongpeng Xie, Xiaomin Li.
      The systemic inflammatory response caused by various pathogenic factors is a key stage in the development of acute respiratory distress syndrome (ARDS). At present, suppression of the inflammatory response and symptomatic support are main methods for the treatment of ARDS. Alveolar epithelial autophagy has an important role in the regulation of the inflammatory response in ARDS. Autophagy is a normal immune mechanism in the body, and it is a metabolic process by which phagocytes degrade intracellular components with the help of lysosomes to maintain intracellular homeostasis. Current studies have shown that pathogenic factors both inside and outside the lung can cause alveolar epithelial cells to form an unfavorable internal environment of hypoxia, starvation, infection, and even apoptosis by triggering inflammatory responses, leading to autophagy dysfunction. Excessive autophagy activation can continue to aggravate inflammatory responses. Autophagy related proteins such as Beclin1, microtubule-associated protein 1 light chain 3 (LC3), mammalian target of rapamycin (mTOR), and p62 are common autophagic markers in current research, which play a crucial role in regulating the autophagic process and the development of lung injury. Therefore, the expression of cellular autophagy genes can be used as early markers and important mechanisms of lung injury in septic ARDS. The Hippo signaling pathway is derived from the protein kinase Hippo in Drosophila, and the Hippo and autophagy are two conserved pathways that are essential for the protection of homeostasis in vivo. The mutual regulation of Hippo signaling pathway and autophagy is currently a hot topic in the academic community. This paper reviews the relevant literature to explore whether the Hippo signaling pathway can regulate cellular autophagy to alleviate the inflammatory response in septic ARDS, so as to provide further research directions for the treatment of ARDS.
    DOI:  https://doi.org/10.3760/cma.j.cn121430-20220705-00633
  33. Nat Commun. 2023 Aug 18. 14(1): 5031
    Mitochondria are secreted in extracellular vesicles when lysosomal function is impaired.
    Wenjing Liang, Shakti Sagar, Rishith Ravindran, Rita H Najor, Justin M Quiles, Liguo Chi, Rachel Y Diao, Benjamin P Woodall, Leonardo J Leon, Erika Zumaya, Jason Duran, David M Cauvi, Antonio De Maio, Eric D Adler, Åsa B Gustafsson.
      Mitochondrial quality control is critical for cardiac homeostasis as these organelles are responsible for generating most of the energy needed to sustain contraction. Dysfunctional mitochondria are normally degraded via intracellular degradation pathways that converge on the lysosome. Here, we identified an alternative mechanism to eliminate mitochondria when lysosomal function is compromised. We show that lysosomal inhibition leads to increased secretion of mitochondria in large extracellular vesicles (EVs). The EVs are produced in multivesicular bodies, and their release is independent of autophagy. Deletion of the small GTPase Rab7 in cells or adult mouse heart leads to increased secretion of EVs containing ubiquitinated cargos, including intact mitochondria. The secreted EVs are captured by macrophages without activating inflammation. Hearts from aged mice or Danon disease patients have increased levels of secreted EVs containing mitochondria indicating activation of vesicular release during cardiac pathophysiology. Overall, these findings establish that mitochondria are eliminated in large EVs through the endosomal pathway when lysosomal degradation is inhibited.
    DOI:  https://doi.org/10.1038/s41467-023-40680-5
  34. BMC Genomics. 2023 Aug 15. 24(1): 456
    Evolutionary analysis of the mTOR pathway provide insights into lifespan extension across mammals.
    Fei Yang, Xing Liu, Yi Li, Zhenpeng Yu, Xin Huang, Guang Yang, Shixia Xu.
      BACKGROUND: Lifespan extension has independently evolved several times during mammalian evolution, leading to the emergence of a group of long-lived animals. Though mammalian/mechanistic target of rapamycin (mTOR) signaling pathway is shown as a central regulator of lifespan and aging, the underlying influence of mTOR pathway on the evolution of lifespan in mammals is not well understood.RESULTS: Here, we performed evolution analyses of 72 genes involved in the mTOR network across 48 mammals to explore the underlying mechanism of lifespan extension. We identified a total of 20 genes with significant evolution signals unique to long-lived species, including 12 positively selected genes, four convergent evolution genes, and five longevity associated genes whose evolution rate related to the maximum lifespan (MLS). Of these genes, four positively selected genes, two convergent evolution genes and one longevity-associated gene were involved in the autophagy response and aging-related diseases, while eight genes were known as cancer genes, indicating the long-lived species might have evolved effective regulation mechanisms of autophagy and cancer to extend lifespan.
    CONCLUSION: Our study revealed genes with significant evolutionary signals unique to long-lived species, which provided new insight into the lifespan extension of mammals and might bring new strategies to extend human lifespan.
    Keywords:  Autophagy; Cancer; Longevity; Mammals; mTOR
    DOI:  https://doi.org/10.1186/s12864-023-09554-4
  35. aBIOTECH. 2023 Jun;4(2): 83-96
    Pepino mosaic virus antagonizes plant m6A modification by promoting the autophagic degradation of the m6A writer HAKAI.
    Hao He, Linhao Ge, Zhaolei Li, Xueping Zhou, Fangfang Li.
      Autophagy plays an active anti-viral role in plants. Increasing evidence suggests that viruses can inhibit or manipulate autophagy, thereby winning the arms race between plants and viruses. Here, we demonstrate that overexpression of an m6A writer from Solanum lycopersicum, SlHAKAI, could negatively regulate pepino mosaic virus (PepMV) infection, inhibit viral RNA and protein accumulations by affecting viral m6A levels in tomato plants and vice versa. The PepMV-encoded RNA-dependent RNA polymerase (RdRP) directly interacts with SlHAKAI and reduces its protein accumulation. The RdRP-mediated decreased protein accumulation of SlHAKAI is sensitive to the autophagy inhibitor 3-methyladenine and is compromised by knocking down a core autophagy gene. Furthermore, PepMV RdRP could interact with an essential autophagy-related protein, SlBeclin1. RdRP, SlHAKAI, and SlBeclin1 interaction complexes form bright granules in the cytoplasm. Silencing of Beclin1 in Nicotiana benthamiana plants abolishes the RdRP-mediated degradation of SlHAKAI, indicating the requirement of Beclin1 in this process. This study uncovers that the PepMV RdRP exploits the autophagy pathway by interacting with SlBeclin1 to promote the autophagic degradation of the SlHAKAI protein, thereby inhibiting the m6A modification-mediated plant defense responses.Supplementary Information: The online version contains supplementary material available at 10.1007/s42994-023-00097-6.
    Keywords:  Autophagy; Beclin1; HAKAI; Pepino mosaic virus
    DOI:  https://doi.org/10.1007/s42994-023-00097-6
  36. Neurobiol Aging. 2023 Jul 17. pii: S0197-4580(23)00151-3. [Epub ahead of print]131 74-87
    Age-related deficits in retinal autophagy following intraocular pressure elevation in autophagy reporter mouse model.
    Brianna C Afiat, Da Zhao, Vickie H Y Wong, Nirma D Perera, Bradley J Turner, Christine T O Nguyen, Bang V Bui.
      This study quantified age-related changes to retinal autophagy using the CAG-RFP-EGFP-LC3 autophagy reporter mice and considered how aging impacts autophagic responses to acute intraocular pressure (IOP) stress. IOP was elevated to 50 mm Hg for 30 minutes in 3-month-old and 12-month-old CAG-RFP-EGFP-LC3 (n = 7 per age group) and Thy1-YFPh transgenic mice (n = 3 per age group). Compared with younger eyes, older eyes showed diminished basal autophagy in the outer retina, while the inner retina was unaffected. Autophagic flux (red:yellow puncta ratio) was elevated in the inner plexiform layer. Three days following IOP elevation, older eyes showed poorer functional recovery, most notably in ganglion cell responses compared to younger eyes (12 months old: -33.4 ± 5.3% vs. 3 months mice: -13.4 ± 4.5%). This paralleled a reduced capacity to upregulate autophagic puncta volume in the inner retina in older eyes, a response that was seen in younger eyes. Age-related decline in basal and stress-induced autophagy in the retina is associated with greater retinal ganglion cells' susceptibility to IOP elevation.
    Keywords:  CAG-RFP-EGFP-LC3; Confocal microscopy; Electroretinography; Glaucoma; Macroautophagy; Retinal neurodegeneration
    DOI:  https://doi.org/10.1016/j.neurobiolaging.2023.07.009
  37. Signal Transduct Target Ther. 2023 08 16. 8(1): 304
    The mitophagy pathway and its implications in human diseases.
    Shouliang Wang, Haijiao Long, Lianjie Hou, Baorong Feng, Zihong Ma, Ying Wu, Yu Zeng, Jiahao Cai, Da-Wei Zhang, Guojun Zhao.
      Mitochondria are dynamic organelles with multiple functions. They participate in necrotic cell death and programmed apoptotic, and are crucial for cell metabolism and survival. Mitophagy serves as a cytoprotective mechanism to remove superfluous or dysfunctional mitochondria and maintain mitochondrial fine-tuning numbers to balance intracellular homeostasis. Growing evidences show that mitophagy, as an acute tissue stress response, plays an important role in maintaining the health of the mitochondrial network. Since the timely removal of abnormal mitochondria is essential for cell survival, cells have evolved a variety of mitophagy pathways to ensure that mitophagy can be activated in time under various environments. A better understanding of the mechanism of mitophagy in various diseases is crucial for the treatment of diseases and therapeutic target design. In this review, we summarize the molecular mechanisms of mitophagy-mediated mitochondrial elimination, how mitophagy maintains mitochondrial homeostasis at the system levels and organ, and what alterations in mitophagy are related to the development of diseases, including neurological, cardiovascular, pulmonary, hepatic, renal disease, etc., in recent advances. Finally, we summarize the potential clinical applications and outline the conditions for mitophagy regulators to enter clinical trials. Research advances in signaling transduction of mitophagy will have an important role in developing new therapeutic strategies for precision medicine.
    DOI:  https://doi.org/10.1038/s41392-023-01503-7
  38. Curr Biol. 2023 Aug 04. pii: S0960-9822(23)00977-6. [Epub ahead of print]
    Host nutrient sensing is mediated by mTOR signaling in cnidarian-dinoflagellate symbiosis.
    Philipp A Voss, Sebastian G Gornik, Marie R Jacobovitz, Sebastian Rupp, Melanie Dörr, Ira Maegele, Annika Guse.
      To survive in the nutrient-poor waters of the tropics, reef-building corals rely on intracellular, photosynthetic dinoflagellate symbionts. Photosynthates produced by the symbiont are translocated to the host, and this enables corals to form the structural foundation of the most biodiverse of all marine ecosystems. Although the regulation of nutrient exchange between partners is critical for ecosystem stability and health, the mechanisms governing how nutrients are sensed, transferred, and integrated into host cell processes are largely unknown. Ubiquitous among eukaryotes, the mechanistic target of the rapamycin (mTOR) signaling pathway integrates intracellular and extracellular stimuli to influence cell growth and cell-cycle progression and to balance metabolic processes. A functional role of mTOR in the integration of host and symbiont was demonstrated in various nutritional symbioses, and a similar role of mTOR was proposed for coral-algal symbioses. Using the endosymbiosis model Aiptasia, we examined the role of mTOR signaling in both larvae and adult polyps across various stages of symbiosis. We found that symbiosis enhances cell proliferation, and using an Aiptasia-specific antibody, we localized mTOR to symbiosome membranes. We found that mTOR signaling is activated by symbiosis, while inhibition of mTOR signaling disrupts intracellular niche establishment and symbiosis altogether. Additionally, we observed that dysbiosis was a conserved response to mTOR inhibition in the larvae of a reef-building coral species. Our data confim that mTOR signaling plays a pivotal role in integrating symbiont-derived nutrients into host metabolism and symbiosis stability, ultimately allowing symbiotic cnidarians to thrive in challenging environments.
    DOI:  https://doi.org/10.1016/j.cub.2023.07.038
  39. Reprod Sci. 2023 Aug 16.
    Prohibitin2/PHB2, Transcriptionally Regulated by GABPA, Inhibits Cell Growth via PRKN/Parkin-dependent Mitophagy in Endometriosis.
    Yupeng Deng, Tong Lou, Lili Kong, Chongdong Liu.
      Endometriosis (EMS) is a common benign gynecological disease affecting women of reproductive age. It is characterized by abnormal growth of endometrial tissue outside the uterine cavity, resulting in chronic pelvic pain and infertility. Endometrial physiological and pathological processes are intimately connected to autophagy. Mitophagy is an essential selective mode that protects cells from metabolic stress and hypoxia. Mitochondrial autophagy mediated by prohibitin 2 (PHB2) is dependent on the PRKN/Parkin pathway and is involved in numerous human diseases. Uncertainty remains as to whether mitophagy regulation by PHB2 contributes to the occurrence and progression of EMS. This study aims to investigate the mechanism underlying the role of PHB2 in EMS. This study detected the protein and mRNA expression of PHB2 in ectopic and normal endometrial tissues of ovarian EMS, in addition to ectopic endometrial cell line 12Z and endometrial stromal cell line KC02-44D for gene overexpression or knockdown. Cell function experiments and mitochondrial function experiments were conducted to investigate the role of PHB2 in the endometrium. Bioinformatic analysis and experiments were also used to investigate the upstream transcription factors that influence PHB2 expression. PHB2 was downregulated in ectopic endometrium, and PHB2 overexpression inhibited cell proliferation, migration, and invasion and promoted apoptosis. The upregulation of mitophagy markers, including Parkin and LC3II/I, and the downregulation of autophagy degradation markers P62 and TOMM20 in EMS suggest that PHB2 may contribute to cell proliferation, migration, invasion, and apoptosis via PRKN/Parkin-mediated mitophagy. Analysis and validation of bioinformatics data revealed that the transcription factor GABPA binds directly to the PHB2 promoter region and controls the transcriptional expression of PHB2. This study investigated the role of PHB2 in the onset of EMS. It inhibits EMS growth via PRKN/Parkin-mediated mitophagy, and GABPA controls the transcriptional disorder of PHB2. This study's findings suggest a novel method for investigating the clinical potential of PHB2 in EMS.
    Keywords:  Endometriosis; GABPA; Mitophagy; PHB2; PRKN/Parkin
    DOI:  https://doi.org/10.1007/s43032-023-01316-7
  40. Proc Natl Acad Sci U S A. 2023 Aug 22. 120(34): e2211281120
    The autophagy machinery interacts with EBV capsids during viral envelope release.
    Maria Pena-Francesch, Liliana Danusia Vanoaica, Gao-Feng Zhu, Michael Stumpe, Devanarayanan Siva Sankar, Heike Nowag, Alma Delia Valencia-Camargo, Wolfgang Hammerschmidt, Jörn Dengjel, Laure-Anne Ligeon, Christian Münz.
      Autophagy serves as a defense mechanism against intracellular pathogens, but several microorganisms exploit it for their own benefit. Accordingly, certain herpesviruses include autophagic membranes into their infectious virus particles. In this study, we analyzed the composition of purified virions of the Epstein-Barr virus (EBV), a common oncogenic γ-herpesvirus. In these, we found several components of the autophagy machinery, including membrane-associated LC3B-II, and numerous viral proteins, such as the capsid assembly proteins BVRF2 and BdRF1. Additionally, we showed that BVRF2 and BdRF1 interact with LC3B-II via their common protein domain. Using an EBV mutant, we identified BVRF2 as essential to assemble mature capsids and produce infectious EBV. However, BdRF1 was sufficient for the release of noninfectious viral envelopes as long as autophagy was not compromised. These data suggest that BVRF2 and BdRF1 are not only important for capsid assembly but together with the LC3B conjugation complex of ATG5-ATG12-ATG15L1 are also critical for EBV envelope release.
    Keywords:  EBV; autophagy; viral capsid assembly; viral envelope; xenophagy
    DOI:  https://doi.org/10.1073/pnas.2211281120
  41. iScience. 2023 Aug 18. 26(8): 107475
    Autophagy ablation in skeletal muscles worsens sepsis-induced muscle wasting, impairs whole-body metabolism, and decreases survival.
    Jean-Philippe Leduc-Gaudet, Kayla Miguez, Marina Cefis, Julie Faitg, Alaa Moamer, Tomer Jordi Chaffer, Olivier Reynaud, Felipe E Broering, Anwar Shams, Dominique Mayaki, Laurent Huck, Marco Sandri, Gilles Gouspillou, Sabah N A Hussain.
      Septic patients frequently develop skeletal muscle wasting and weakness, resulting in severe clinical consequences and adverse outcomes. Sepsis triggers sustained induction of autophagy, a key cellular degradative pathway, in skeletal muscles. However, the impact of enhanced autophagy on sepsis-induced muscle dysfunction remains unclear. Using an inducible and muscle-specific Atg7 knockout mouse model (Atg7iSkM-KO), we investigated the functional importance of skeletal muscle autophagy in sepsis using the cecal ligation and puncture model. Atg7iSkM-KO mice exhibited a more severe phenotype in response to sepsis, marked by severe muscle wasting, hypoglycemia, higher ketone levels, and a decreased in survival as compared to mice with intact Atg7. Sepsis and Atg7 deletion resulted in the accumulation of mitochondrial dysfunction, although sepsis did not further worsen mitochondrial dysfunction in Atg7iSkM-KO mice. Overall, our study demonstrates that autophagy inactivation in skeletal muscles triggers significant worsening of sepsis-induced muscle and metabolic dysfunctions and negatively impacts survival.
    Keywords:  Genetics; Human metabolism; Musculoskeletal medicine
    DOI:  https://doi.org/10.1016/j.isci.2023.107475
  42. Trends Cell Biol. 2023 Aug 14. pii: S0962-8924(23)00154-X. [Epub ahead of print]
    Autophagy in intestinal epithelial cells prevents gut inflammation.
    Shahar Telpaz, Shai Bel.
      Intestinal epithelial cells form the largest barrier in the body, separating us from the outside world. Here, we review recent findings that highlight the role of autophagy in the cell-intrinsic response of the epithelial cells to the harsh intestinal environment and how they shape host physiology.
    Keywords:  autophagy; epithelium; inflammation; inflammatory bowel diseases; intestinal barrier; intestine
    DOI:  https://doi.org/10.1016/j.tcb.2023.07.010
  43. Cell Rep. 2023 Aug 11. pii: S2211-1247(23)00986-5. [Epub ahead of print]42(8): 112975
    LHPP-mediated inorganic pyrophosphate hydrolysis-driven lysosomal acidification in astrocytes regulates adult neurogenesis.
    Longze Sha, Jing Li, Hui Shen, Qingyu Wang, Peixin Meng, Xiuneng Zhang, Yu Deng, Wanwan Zhu, Qi Xu.
      In bacteria, archaea, protists, and plants, the hydrolysis of pyrophosphate (PPi) by inorganic pyrophosphatase (PPase) can, under stress conditions, substitute for ATP-driven proton flux to generate a proton gradient and induce luminal acidification. However, this strategy is considered to be lost in eukaryotes. Here, we report that LHPP, a poorly understood PPase that exhibits activity at acidic pH, is primarily expressed in astrocytes and partly localized on lysosomal membranes. Under stress conditions, LHPP is recruited to vacuolar ATPase (V-ATPase) and facilitates V-ATPase-dependent proton transport and lysosomal acidification by hydrolyzing PPi. LHPP knockout (KO) mice have no discernable phenotype but are resilient to chronic-stress-induced depression-like behaviors. Mechanistically, LHPP deficiency prevents lysosome-dependent degradation of C/EBPβ and induces the expression of a group of chemokines that promote adult neurogenesis. Together, these findings suggest that LHPP is likely to be a therapeutic target for stress-related brain disease.
    Keywords:  CP: Cell biology; CP: Neuroscience
    DOI:  https://doi.org/10.1016/j.celrep.2023.112975
  44. Genetics. 2023 Aug 18. pii: iyad154. [Epub ahead of print]
    Autophagy impairment and lifespan reduction caused by Atg1 RNAi or Atg18 RNAi expression in adult fruit flies (Drosophila melanogaster).
    Mariah Bierlein, Joseph Charles, Trevor Polisuk-Balfour, Heidi Bretscher, Micaela Rice, Jacklyn Zvonar, Drake Pohl, Lindsey Winslow, Brennah Wasie, Sara Deurloo, Jordan Van Wert, Britney Williams, Gabrielle Ankney, Zachary Harmon, Erica Dann, Anna Azuz, Alex Guzman-Vargas, Elizabeth Kuhns, Thomas P Neufeld, Michael B O'Connor, Felix Amissah, Changqi C Zhu.
      Autophagy, an autophagosome and lysosome-based eukaryotic cellular degradation system, has previously been implicated in lifespan regulation in different animal models. In this report, we show that expression of the RNAi transgenes targeting the transcripts of the key autophagy genes Atg1 or Atg18 in adult fly muscle or glia does not affect the overall levels of autophagosomes in those tissues and does not change the lifespan of the tested flies, but lifespan reduction phenotype has become apparent when Atg1 RNAi or Atg18 RNAi is expressed ubiquitously in adult flies or after autophagy is eradicated through the knockdown of Atg1 or Atg18 in adult fly adipocytes. Lifespan reduction was also observed when Atg1 or Atg18 was knocked down in adult fly enteroblasts and midgut stem cells. Over-expression of wild type Atg1 in adult fly muscle or adipocytes reduces lifespan and causes accumulation of high levels of ubiquitinated protein aggregates in muscles. Our research data have highlighted the important functions of the key autophagy genes in adult fly adipocytes, enteroblasts, and midgut stem cells and their undetermined roles in adult fly muscle and glia for lifespan regulation.
    Keywords:   Drosophila melanogaster ; Atg1; Atg18; Atg5; Atg9; aging; autophagy; fruit fly; lifespan
    DOI:  https://doi.org/10.1093/genetics/iyad154
  45. Am J Physiol Renal Physiol. 2023 Aug 17.
    Differential Regulation of Autophagy on Urine-Concentrating Capability through Modulating the Renal AQP2 Expression and Renin-Angiotensin System in Mice.
    Chuanming Xu, Xiaoli Yi, Le Tang, Hui Wang, Shuhan Chu, Jun Yu.
      Autophagy, a cellular process of "self-eating", plays an essential role in renal pathophysiology. However, the effect of autophagy on urine-concentrating ability in physiological conditions is still unknown. This study aimed to determine the relevance and mechanisms of autophagy for maintaining urine-concentrating capability during antidiuresis. The extent of the autophagic response to water deprivation (WD) was different between the renal cortex and medulla in mice. Autophagy activity levels in the renal cortex were initially suppressed and then stimulated by WD in a time‑dependent manner. During 48h WD, the urine-concentrating capability of mice was impaired by rapamycin but not 3-Methyladenine, accompanied by the suppressed renal aquaporin 2 (AQP2), V2 receptor (V2R), renin, and angiotensin-converting enzyme (ACE) expression, and the levels of prorenin/renin, angiotensin II (AngII), and aldosterone in the plasma and urine. In contrast, 3-Methyladenine and chloroquine suppressed the urine-concentrating capability in WD72 mice, accompanied by downregulation of AQP2 and V2R expression in the renal cortex. 3-Methyladenine and chloroquine further increased AQP2 and V2R expression in the renal medulla of WD72 mice. Compared to 3-MA and CQ, Rapa administration yielded completely opposite results on the above parameters in WD72 mice. In addition, 3-Methyladenine and chloroquine abolished the upregulation of prorenin/renin, AngII, and aldosterone levels in the plasma and urine in WD72mice. Taken together, our study demonstrated that autophagy regulated urine-concentrating capability through differential regulation of the renal AQP2/V2R and ACE/AngII signaling during WD.
    Keywords:  Autophagy; aquaporin-2; renin-angiotensin system; urinary concentration; water dehydration
    DOI:  https://doi.org/10.1152/ajprenal.00018.2023
  46. Oncogene. 2023 Aug 17.
    YAP governs cellular adaptation to perturbation of glutamine metabolism by regulating ATF4-mediated stress response.
    Minjoong Kim, Sunsook Hwang, Byungjoo Kim, Seungmin Shin, Seungyeon Yang, Jihye Gwak, Seung Min Jeong.
      Proliferating cells have metabolic dependence on glutamine to fuel anabolic pathways and to refill the mitochondrial carbon pool. The Hippo pathway is essential for coordinating cell survival and growth with nutrient availability, but no molecular connection to glutamine deprivation has been reported. Here, we identify a non-canonical role of YAP, a key effector of the Hippo pathway, in cellular adaptation to perturbation of glutamine metabolism. Whereas YAP is inhibited by nutrient scarcity, enabling cells to restrain proliferation and to maintain energy homeostasis, glutamine shortage induces a rapid YAP dephosphorylation and activation. Upon glutaminolysis inhibition, an increased reactive oxygen species production inhibits LATS kinase via RhoA, leading to YAP dephosphorylation. Activated YAP promotes transcriptional induction of ATF4 to induce the expression of genes involved in amino acid homeostasis, including Sestrin2. We found that YAP-mediated Sestrin2 induction is crucial for cell viability during glutamine deprivation by suppressing mTORC1. Thus, a critical relationship between YAP, ATF4, and mTORC1 is uncovered by our findings. Finally, our data indicate that targeting the Hippo-YAP pathway in combination with glutaminolysis inhibition may provide potential therapeutic approaches to treat tumors.
    DOI:  https://doi.org/10.1038/s41388-023-02811-6
  47. Mol Neurodegener. 2023 Aug 15. 18(1): 56
    Oleoylethanolamide facilitates PPARα and TFEB signaling and attenuates Aβ pathology in a mouse model of Alzheimer's disease.
    Michele M Comerota, Manasee Gedam, Wen Xiong, Feng Jin, Lisheng Deng, Meng C Wang, Jin Wang, Hui Zheng.
      BACKGROUND: Age is the strongest risk factor for the development of Alzheimer's disease (AD). Besides the pathological hallmarks of β-amyloid (Aβ) plaques and neurofibrillary tangles, emerging evidence demonstrates a critical role of microglia and neuroinflammation in AD pathogenesis. Oleoylethanolamide (OEA) is an endogenous lipid amide that has been shown to promote lifespan and healthspan in C. elegans through regulation of lysosome-to-nucleus signaling and cellular metabolism. The goal of our study was to determine the role of OEA in the mediation of microglial activity and AD pathology using its stable analog, KDS-5104.METHODS: We used primary microglial cultures and genetic and pharmacological approaches to examine the signaling mechanisms and functional roles of OEA in mediating Aβ phagocytosis and clearance, lipid metabolism and inflammasome formation. Further, we tested the effect of OEA in vivo in acute LPS-induced neuroinflammation and by chronic treatment of 5xFAD mice.
    RESULTS: We found that OEA activates PPARα signaling and its downstream cell-surface receptor CD36 activity. In addition, OEA promotes TFEB lysosomal function in a PPARα-dependent but mTORC1-independent manner, the combination of which leads to enhanced microglial Aβ uptake and clearance. These are associated with the suppression of LPS-induced lipid droplet accumulation and inflammasome activation. Chronic treatment of 5xFAD mice with KDS-5104 restored dysregulated lipid profiles, reduced reactive gliosis and Aβ pathology and rescued cognitive impairments.
    CONCLUSION: Together, our study provides support that augmenting OEA-mediated lipid signaling may offer therapeutic benefit against aging and AD through modulating lipid metabolism and microglia phagocytosis and clearance.
    Keywords:  Alzheimer’s disease; Microglia; Oleoylethanolamide; PPARα, TFEB
    DOI:  https://doi.org/10.1186/s13024-023-00648-x
  48. Otol Neurotol. 2023 Aug 15.
    Enhanced Mitophagy in Cholesteatoma Epithelial Cells.
    Quan-Cheng Li, Shu-Qi Wang, Zai-Zai Cao, Shui-Hong Zhou.
      HYPOTHESIS: Mitophagy may have a potential role in the pathogenesis of acquired cholesteatoma.BACKGROUND: Enhanced mitophagy has been proven to be involved in various cancers. However, its role in the pathogenesis of cholesteatoma, which shares some common features with cancer, is controversial. This study investigated mitophagy in cholesteatoma epithelial cells.
    METHODS: The autophagy protein markers LC3-II and p62 and mitophagy proteins BNIP3, Parkin, and PINK1 were analyzed in cholesteatoma epithelial cells and external auditory canal epithelium cells by immunoblotting. The results were confirmed by immunohistochemistry. Adenovirus Ad-mCherry-GFP-LC3B and Ad-GFP-LC3B were used to evaluate autophagic activity. Transmission electron microscopy was used to observe and analyze autophagosomes.
    RESULTS: LC3-II expression was increased in cholesteatoma cells, whereas soluble and insoluble p62 levels were decreased. The expressions of BNIP3, Parkin, and PINK1 were higher in total protein and mitochondrial protein of cholesteatoma cells compared with normal external auditory canal epithelium cells. Autophagic activity was increased in cholesteatoma cells compared with normal external auditory canal epithelium cells.
    CONCLUSION: Mitophagy was enhanced in cholesteatoma epithelial cells and may have a potential role in the pathogenesis of acquired cholesteatoma.
    DOI:  https://doi.org/10.1097/MAO.0000000000003986
  49. J Biol Chem. 2023 Aug 10. pii: S0021-9258(23)02182-8. [Epub ahead of print] 105154
    Quantitative proteomics and phosphoproteomics of PP2A-PPP2R5D variants reveal deregulation of RPS6 phosphorylation via converging signaling cascades.
    K A Smolen, C M Papke, M R Swingle, A Musiyenko, C Li, E A Salter, A D Camp, R E Honkanen, A N Kettenbach.
      Genetic germline variants of PPP2R5D (encoding: phosphoprotein phosphatase-2 regulatory protein-5D) result in PPP2R5D-related disorder (Jordan's Syndrome), which is characterized by intellectual disability, hypotonia, seizures, macrocephaly, autism spectrum disorder, and delayed motor skill development. The disorder originates from de novo single nucleotide mutations, generating missense variants that act in a dominant manner. Pathogenic mutations altering 13 different amino acids have been identified, with the E198K variant accounting for ∼40% of reported cases. However, the generation of a heterozygous E198K variant cell line to study the molecular effects of the pathogenic mutation has been challenging. Here, we use CRISPR-PRIME genomic editing to introduce a transition (c.592G>A) in a single PPP2R5D allele in HEK293 cells, generating E198K-heterozygous lines to complement existing E420K variant lines. We generate global protein and phosphorylation profiles of WT, E198K, and E420K cell lines and find unique and shared changes between variants and WT cells in kinase- and phosphatase-controlled signaling cascades. We observed ribosomal protein S6 (RPS6) hyperphosphorylation as a shared signaling alteration, indicative of increased ribosomal protein S6-kinase activity. Treatment with rapamycin or an RPS6-kinase inhibitor (LY2584702) suppressed RPS6 phosphorylation in both, suggesting upstream activation of mTORC1/p70S6K. Intriguingly, our data suggests ERK-dependent activation of mTORC1 in both E198K and E420K variant cells, with additional AKT-mediated mTORC1 activation in the E420K variant. Thus, although upstream activation of mTORC1 differs between PPP2R5D-related disorder genotypes, inhibition of mTORC1 or RPS6-kinases warrants further investigation as potential therapeutic strategies for patients.
    Keywords:  Jordan’s Syndrome; LY2584702; PP2A; PPP2R5D; PPP2R5D-related neurodevelopmental disorder; Phosphatase; Phosphoproteomics; Proteomics; mTOR; rapamycin
    DOI:  https://doi.org/10.1016/j.jbc.2023.105154
  50. Genes Dis. 2024 Jan;11(1): 367-381
    Autophagy-related lncRNAs in tumor progression and drug resistance: A double-edged sword.
    Yunchao Zhang, Jiayu Tang, Cheng Wang, Qinxiu Zhang, Anqi Zeng, Linjiang Song.
      The incidence and mortality rates of cancer are increasing every year worldwide but the survival rate of cancer patients is still unsatisfactory. Therefore, it is necessary to further elucidate the molecular mechanisms involved in tumor development and drug resistance to improve cancer cure or survival rates. In recent years, autophagy has become a hot topic in the field of oncology research, which plays a double-edged role in tumorigenesis, progression, and drug resistance. Meanwhile, long non-coding RNA (lncRNA) has also been shown to regulate autophagy, and the two-sided nature of autophagy determines the dual regulatory role of autophagy-related lncRNAs (ARlncRNAs). Therefore, ARlncRNAs can be effective therapeutic targets for various cancers. Furthermore, the high abundance and stability of ARlncRNAs in tumor tissues make them promising biomarkers. In this review, we summarized the roles and mechanisms of ARlncRNAs in tumor cell proliferation, apoptosis, migration, invasion, drug resistance, angiogenesis, radiation resistance, and immune regulation. In addition, we described the clinical significance of these ARlncRNAs, including as biomarkers/therapeutic targets and their association with clinical drugs.
    Keywords:  Apoptosis; Autophagy; Biomarker; Cancer; Drug resistance; LncRNA
    DOI:  https://doi.org/10.1016/j.gendis.2023.04.015
  51. J Proteome Res. 2023 Aug 16.
    Proteomic Investigation of Differential Interactomes of Glypican 1 and a Putative Disease-Modifying Variant of Ataxia.
    Nur Cengiz Winter, Mert Karakaya, Peter Mosen, Isabell Brusius, Banu Anlar, Goknur Haliloglu, Dominic Winter, Brunhilde Wirth.
      In a currently 13-year-old girl of consanguineous Turkish parents, who developed unsteady gait and polyneuropathy at the ages of 3 and 6 years, respectively, we performed whole genome sequencing and identified a biallelic missense variant c.424C>T, p.R142W in glypican 1 (GPC1) as a putative disease-associated variant. Up to date, GPC1 has not been associated with a neuromuscular disorder, and we hypothesized that this variant, predicted as deleterious, may be causative for the disease. Using mass spectrometry-based proteomics, we investigated the interactome of GPC1 WT and the missense variant. We identified 198 proteins interacting with GPC1, of which 16 were altered for the missense variant. This included CANX as well as vacuolar ATPase (V-ATPase) and the mammalian target of rapamycin complex 1 (mTORC1) complex members, whose dysregulation could have a potential impact on disease severity in the patient. Importantly, these proteins are novel interaction partners of GPC1. At 10.5 years, the patient developed dilated cardiomyopathy and kyphoscoliosis, and Friedreich's ataxia (FRDA) was suspected. Given the unusually severe phenotype in a patient with FRDA carrying only 104 biallelic GAA repeat expansions in FXN, we currently speculate that disturbed GPC1 function may have exacerbated the disease phenotype. LC-MS/MS data are accessible in the ProteomeXchange Consortium (PXD040023).
    Keywords:  Friedreich’s ataxia; GPC1; GPC1 interactome; MS-based proteomics; disease modifier; neuromuscular disorder
    DOI:  https://doi.org/10.1021/acs.jproteome.3c00402
  52. PLoS Biol. 2023 Aug 17. 21(8): e3002231
    NCoR1 controls Mycobacterium tuberculosis growth in myeloid cells by regulating the AMPK-mTOR-TFEB axis.
    Viplov Kumar Biswas, Kaushik Sen, Abdul Ahad, Arup Ghosh, Surbhi Verma, Rashmirekha Pati, Subhasish Prusty, Sourya Prakash Nayak, Sreeparna Podder, Dhiraj Kumar, Bhawna Gupta, Sunil Kumar Raghav.
      Mycobacterium tuberculosis (Mtb) defends host-mediated killing by repressing the autophagolysosome machinery. For the first time, we report NCoR1 co-repressor as a crucial host factor, controlling Mtb growth in myeloid cells by regulating both autophagosome maturation and lysosome biogenesis. We found that the dynamic expression of NCoR1 is compromised in human peripheral blood mononuclear cells (PBMCs) during active Mtb infection, which is rescued upon prolonged anti-mycobacterial therapy. In addition, a loss of function in myeloid-specific NCoR1 considerably exacerbates the growth of M. tuberculosis in vitro in THP1 differentiated macrophages, ex vivo in bone marrow-derived macrophages (BMDMs), and in vivo in NCoR1MyeKO mice. We showed that NCoR1 depletion controls the AMPK-mTOR-TFEB signalling axis by fine-tuning cellular adenosine triphosphate (ATP) homeostasis, which in turn changes the expression of proteins involved in autophagy and lysosomal biogenesis. Moreover, we also showed that the treatment of NCoR1 depleted cells by Rapamycin, Antimycin-A, or Metformin rescued the TFEB activity and LC3 levels, resulting in enhanced Mtb clearance. Similarly, expressing NCoR1 exogenously rescued the AMPK-mTOR-TFEB signalling axis and Mtb killing. Overall, our data revealed a central role of NCoR1 in Mtb pathogenesis in myeloid cells.
    DOI:  https://doi.org/10.1371/journal.pbio.3002231
  53. Mol Neurobiol. 2023 Aug 15.
    FGF-18 Protects the Injured Spinal cord in mice by Suppressing Pyroptosis and Promoting Autophagy via the AKT-mTOR-TRPML1 axis.
    Feida Li, Tingwen Cai, Letian Yu, Gaoxiang Yu, Haojie Zhang, Yibo Geng, Jiaxuan Kuang, Yongli Wang, Yuepiao Cai, Jian Xiao, Xiangyang Wang, Jian Ding, Hui Xu, Wenfei Ni, Kailiang Zhou.
      Spinal cord injury (SCI) is a severe medical condition with lasting effects. The efficacy of numerous clinical treatments is hampered by the intricate pathophysiological mechanism of SCI. Fibroblast growth factor 18 (FGF-18) has been found to exert neuroprotective effects after brain ischaemia, but its effect after SCI has not been well explored. The aim of the present study was to explore the therapeutic effect of FGF-18 on SCI and the related mechanism. In the present study, a mouse model of SCI was used, and the results showed that FGF-18 may significantly affect functional recovery. The present findings demonstrated that FGF-18 directly promoted functional recovery by increasing autophagy and decreasing pyroptosis. In addition, FGF-18 increased autophagy, and the well-known autophagy inhibitor 3-methyladenine (3MA) reversed the therapeutic benefits of FGF-18 after SCI, suggesting that autophagy mediates the therapeutic effects of FGF-18 on SCI. A mechanistic study revealed that after stimulation of the protein kinase B (AKT)-transient receptor potential mucolipin 1 (TRPML1)-calcineurin signalling pathway, the FGF-18-induced increase in autophagy was mediated by the dephosphorylation and nuclear translocation of transcription factor E3 (TFE3). Together, these findings indicated that FGF-18 is a robust autophagy modulator capable of accelerating functional recovery after SCI, suggesting that it may be a promising treatment for SCI in the clinic.
    Keywords:  AKT-mTOR-TRPML1 axis; Autophagy; FGF-18; Pyroptosis; Spinal cord injury
    DOI:  https://doi.org/10.1007/s12035-023-03503-8
  54. Curr Res Neurobiol. 2023 ;5 100105
    Propranolol reduces the accumulation of cytotoxic aggregates in C9orf72-ALS/FTD in vitro models.
    Mira Seidel, Sandeep Rajkumar, Christina Steffke, Vivien Noeth, Shreya Agarwal, Kevin Roger, Joanna Lipecka, Albert Ludolph, Chiara Ida Guerrera, Tobias Boeckers, Alberto Catanese.
      Mutations in the C9orf72 gene are the most common cause of familial amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). The pathogenetic mechanisms linked to this gene are a direct consequence of an aberrant intronic expansion of a GGGGCC hexanucleotide located between the 1a and 1b non-coding exons, which can be transcribed to form cytotoxic RNA foci or even translated into aggregation-prone dipeptide repeat proteins. Importantly, the abnormal length of these repeats affects also the expression levels of C9orf72 itself, which suggests haploinsufficiency as additional pathomechanism. Thus, it appears that both toxic gain of function and loss of function are distinct but still coexistent features contributing to the insurgence of the disease in case of C9orf72 mutations. In this study, we aimed at identifying a strategy to address both aspects of the C9orf72-related pathobiochemistry and provide proof-of-principle information for a better understanding of the mechanisms leading to neuronal loss. By using primary neurons overexpressing toxic poly(GA), the most abundant protein product of the GGGGCC repeats, we found that the antiarrhythmic drug propranolol could efficiently reduce the accumulation of aberrant aggregates and increase the survival of C9orf72-related cultures. Interestingly, the improved catabolism appeared to not depend on major degradative pathways such as autophagy and the proteasome. By analyzing the proteome of poly(GA)-expressing neurons after exposure to propranolol, we found that the drug increased lysosomal degradation through a mechanism directly involving C9orf72 protein, whose levels were increased after treatment. Further confirmation of the beneficial effect of the beta blocker on aggregates' accumulation and survival of hiPSC-derived C9orf72-mutant motoneurons strengthened the finding that addressing both facets of C9orf72 pathology might represent a valid strategy for the treatment of these ALS/FTD cases.
    Keywords:  ALS; Aggregates; Autophagy; C9orf72; FTD; Lysosomes; Neurodegeneration; Neurons; Poly(GA); hiPSC
    DOI:  https://doi.org/10.1016/j.crneur.2023.100105
  55. Aging Cell. 2023 Aug 18. e13932
    ApoE4 exacerbates the senescence of hippocampal neurons and spatial cognitive impairment by downregulating acetyl-CoA level.
    Shuixin Lv, Yusi Zhang, Yingbin Lin, Wenting Fang, Yu Wang, Zihang Li, Anlan Lin, Xiaoman Dai, Qinyong Ye, Jing Zhang, Xiaochun Chen.
      Although aging and apolipoprotein E (APOE) ε4 allele have been documented as two major risk factors for late-onset Alzheimer's disease (LOAD), their interaction and potential underlying mechanisms remain unelucidated. Using humanized ApoE4- and ApoE3- target replacement mice, we found the accumulation of senescent neurons and the activation of mTOR and endosome-lysosome-autophagy (ELA) system in the hippocampus of aged ApoE4 mice. Further analyses revealed that ApoE4 aggravated the profile change of hippocampal transcription and metabolism in an age-dependent manner, accompanying with an disruption of metabolism, which is presented with the downregulating activity of citrate synthase, the level of ATP and, most importantly, the level of acetyl coenzyme A (Ac-CoA); GTA supplement, an Ac-CoA substrate, reversed the senescent characteristics, decreased the activation of mTOR and ELA system, and enhanced the synaptic structure and increasing level of pre-/post-synaptic plasticity-related protein, leading to cognitive improvement in aged ApoE4 mice. These data suggest that ApoE4 exacerbates neuronal senescence due to a deficiency of acetyl-CoA, which can be ameliorated by GTA supplement. The findings provide novel insights into the potential therapeutic value of GTA supplement for the cognitive improvement in aged APOE4 carriers.
    Keywords:  Alzheimer's disease; ApoE4; acetate; acetyl-CoA; synaptic plasticity
    DOI:  https://doi.org/10.1111/acel.13932
  56. PLoS One. 2023 ;18(8): e0290002
    The ubiquitin-like modifier FAT10 covalently modifies HUWE1 and strengthens the interaction of AMBRA1 and HUWE1.
    Stefanie Mueller, Johanna Bialas, Stella Ryu, Nicola Catone, Annette Aichem.
      The ubiquitin-like modifier FAT10 is highly upregulated under inflammatory conditions and targets its conjugation substrates to the degradation by the 26S proteasome. This process termed FAT10ylation is mediated by an enzymatic cascade and includes the E1 activating enzyme ubiquitin-like modifier activating enzyme 6 (UBA6), the E2 conjugating enzyme UBA6-specific E2 enzyme 1 (USE1) and E3 ligases, such as Parkin. In this study, the function of the HECT-type ubiquitin E3 ligase HUWE1 was investigated as a putative E3 ligase and/or conjugation substrate of FAT10. Our data provide strong evidence that HUWE1 is FAT10ylated in a UBA6 and FAT10 diglycine-dependent manner in vitro and in cellulo and that the HUWE1-FAT10 conjugate is targeted to proteasomal degradation. Since the mutation of all relevant cysteine residues within the HUWE1 HECT domain did not abolish FAT10 conjugation, a role of HUWE1 as E3 ligase for FAT10ylation is rather unlikely. Moreover, we have identified the autophagy-related protein AMBRA1 as a new FAT10 interaction partner. We show that the HUWE1-FAT10 conjugate formation is diminished in presence of AMBRA1, while the interaction between AMBRA1 and HUWE1 is strengthened in presence of FAT10. This implies a putative interplay of all three proteins in cellular processes such as mitophagy.
    DOI:  https://doi.org/10.1371/journal.pone.0290002
  57. Cell Death Discov. 2023 Aug 18. 9(1): 302
    Cezanne promoted autophagy through PIK3C3 stabilization and PIK3C2A transcription in lung adenocarcinoma.
    Yadong Wang, Jiahao Li, Haotian Zheng, Kai Wang, Xiaoyang Ren, Guanghui Wang, Jiajun Du.
      Osimertinib is a promising approved third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) for treating patients with lung adenocarcinoma (LUAD) harboring EGFR-activating mutations, however, almost all patients develop resistance to Osimertinib eventually limiting the long-term efficacy. Autophagy is a vital cellular recycling process promoting Osimertinib resistance. Identifying accurate and efficient autophagy-regulatory factors is of great significance in reducing Osimertinib resistance. This study identified Cezanne, a member of the ovarian tumor protease (OTU)-deubiquitinating family, as an autophagy regulator. Cezanne was highly expressed in Osimertinib-resistant cells, and Cezanne overexpression promoted Osimertinib resistance, while chloroquine (CQ), an autophagy inhibitor, reverted this process. In the Cezanne-overexpressing cells, autophagy was activated even in the absence of autophagy inducers rapamycin and Earle's Balanced Salt Solution (EBSS). Further study showed that Cezanne stabilized PIK3C3 by deubiquitinating K48-linked ubiquitination at Lysine 322. Surprisingly, as a compensatory mechanism of PI3P generation, PIK3C2A was shown to be upregulated by Cezanne by promoting its transcription in a POLR2A-dependent way. Based on these results, Cezanne also accelerates EGFR recycling which may explain the mechanism mediating Cezanne expression and Osimertinib resistance. In conclusion, this study establishes a new model connecting Cezanne, autophagy, and Osimertinib resistance, opening new avenues to explore the effect of Cezanne and autophagy in LUAD.
    DOI:  https://doi.org/10.1038/s41420-023-01599-4
  58. Acta Pharmacol Sin. 2023 Aug 14.
    Decreased syntaxin17 expression contributes to the pathogenesis of acute pancreatitis in murine models by impairing autophagic degradation.
    Tian-Tian Wang, Li-Chun Zhang, Zhen Qin, Shu-Jun Chen, Jing-Min Zeng, Jing-Yan Li, Lin An, Cai-Yan Wang, Yong Gao, Li-Ming Wang, Zhong-Xiang Zhao, Zhong-Qiu Liu, Shao-Gui Wang.
      Acute pancreatitis (AP) is an inflammatory disease of the exocrine pancreas. Disruptions in organelle homeostasis, including macroautophagy/autophagy dysfunction and endoplasmic reticulum (ER) stress, have been implicated in human and rodent pancreatitis. Syntaxin 17 (STX17) belongs to the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) subfamily. The Qa-SNARE STX17 is an autophagosomal SNARE protein that interacts with SNAP29 (Qbc-SNARE) and the lysosomal SNARE VAMP8 (R-SNARE) to drive autophagosome-lysosome fusion. In this study, we investigated the role of STX17 in the pathogenesis of AP in male mice or rats induced by repeated intraperitoneal injections of cerulein. We showed that cerulein hyperstimulation induced AP in mouse and rat models, which was characterized by increased serum amylase and lipase activities, pancreatic edema, necrotic cell death and the infiltration of inflammatory cells, as well as markedly decreased pancreatic STX17 expression. A similar reduction in STX17 levels was observed in primary and AR42J pancreatic acinar cells treated with CCK (100 nM) in vitro. By analyzing autophagic flux, we found that the decrease in STX17 blocked autophagosome-lysosome fusion and autophagic degradation, as well as the activation of ER stress. Pancreas-specific STX17 knockdown using adenovirus-shSTX17 further exacerbated pancreatic edema, inflammatory cell infiltration and necrotic cell death after cerulein injection. These data demonstrate a critical role of STX17 in maintaining pancreatic homeostasis and provide new evidence that autophagy serves as a protective mechanism against AP.
    Keywords:  ER stress; SNARE; STX17; acute pancreatitis; autophagy; lysosome
    DOI:  https://doi.org/10.1038/s41401-023-01139-x
  59. bioRxiv. 2023 Aug 02. pii: 2023.07.31.551324. [Epub ahead of print]
    CCT and Cullin1 regulate the TORC1 pathway to promote dendritic arborization in health and disease.
    Erin N Lottes, Feyza H Ciger, Shatabdi Bhattacharjee, Emily A Timmins-Wilde, Benoit Tete, Tommy Tran, Jais Matta, Atit A Patel, Daniel N Cox.
      The development of cell-type-specific dendritic arbors is integral to the proper functioning of neurons within their circuit networks. In this study, we examine the regulatory relationship between the cytosolic chaperonin CCT, key insulin pathway genes, and an E3 ubiquitin ligase (Cullin1) in homeostatic dendritic development. CCT loss of function (LOF) results in dendritic hypotrophy in Drosophila Class IV (CIV) multidendritic larval sensory neurons, and CCT has recently been shown to fold components of the TOR (Target of Rapamycin) complex 1 (TORC1), in vitro. Through targeted genetic manipulations, we have confirmed that LOF of CCT and the TORC1 pathway reduces dendritic complexity, while overexpression of key TORC1 pathway genes increases dendritic complexity in CIV neurons. Both CCT and TORC1 LOF significantly reduce microtubule (MT) stability. CCT has been previously implicated in regulating proteinopathic aggregation, thus we examined CIV dendritic development in disease conditions as well. Expression of mutant Huntingtin leads to dendritic hypotrophy in a repeat-length-dependent manner, which can be rescued by TORC1 disinhibition via Cullin1 LOF. Together, our data suggest that Cullin1 and CCT influence dendritic arborization through regulation of TORC1 in both health and disease.SIGNIFICANCE: The insulin pathway has become an increasingly attractive target for researchers interested in understanding the intersection of metabolism and brain health. We have found connections between the insulin pathway and cytosolic protein maintenance in the development of neuronal dendrites. These pathways converge on the dendritic cytoskeleton, particularly microtubules. Neurons expressing mutant Huntingtin also show defects in dendritic development and the underlying cytoskeleton, and we find that disinhibition of the insulin pathway can rescue dendritic hypotrophy in these neurons. This work advances our understanding of the molecular interactions between the insulin pathway and neuronal development in both health and Huntington's Disease conditions.
    DOI:  https://doi.org/10.1101/2023.07.31.551324
  60. Front Neurosci. 2023 ;17 1249815
    Presenilins and mitochondria-an intriguing link: mini-review.
    Mark Makarov, Liliia Kushnireva, Michele Papa, Eduard Korkotian.
      This review uncovers the intricate relationship between presenilins, calcium, and mitochondria in the context of Alzheimer's disease (AD), with a particular focus on the involvement of presenilin mutations in mitochondrial dysfunction. So far, it is unclear whether the impairment of mitochondrial function arises primarily from damage inflicted by β-amyloid upon mitochondria or from the disruption of calcium homeostasis due to presenilins dysfunctions. The roles of presenilins in mitophagy, autophagy, mitochondrial dynamics, and many other functions, non-γ-secretase related, also require close attention in future research. Resolution of contradictions in understanding of presenilins cellular functions are needed for new effective therapeutic strategies for AD.
    Keywords:  Alzheimer’s disease; mitochondria associated membranes; neurodegeneration; presenilins; spine apparatus
    DOI:  https://doi.org/10.3389/fnins.2023.1249815
  61. Biochim Biophys Acta Mol Basis Dis. 2023 Aug 10. pii: S0925-4439(23)00210-7. [Epub ahead of print] 166844
    Orexin-A/OX1R is involved in regulation of autophagy to promote cortisol secretion in adrenocortical cell.
    Xin Guo, Jing Wen, Qianqian Gao, Yuyan Zhao, Yue Zhao, Chunyu Wang, Na Xu, Yaozhong Shao, Xiaocen Chang.
      BACKGROUND: Hypercortisolism has emerged as a prominent clinical condition worldwide caused by biochemical cortisol excess in patients, and optimization treatment is needed urgently in the clinic. Previously, we observed that orexin-A/orexin type 1 receptor (OX1R) promoted cell proliferation, inhibited apoptosis, and increased cortisol release in adrenocortical cells. However, the functions of orexin-A/OX1R on autophagy and its molecular mechanism are not known.METHODS: Transmission electron microscopy and confocal microscope were performed to detect autophagosomes. Western blot were performed to detect autophagy proteins. The cortisol concentration was assessed with an ELISA.
    FINDINGS: Our data demonstrated that orexin-A/OX1R activated the mammalian target of rapamycin/p70 ribosomal protein S6 kinase-1 pathway, thereby inhibiting autophagy in H295R cells and Y-1 cells. Furthermore, the orexin-A/OX1R-mediated suppression of autophagy played a crucial role in cortisol secretion. Mechanistically, the expression of 3β-hydroxysteroid dehydrogenase/isomerase, the rate-limiting enzyme in cortisol synthesis, was increased with autophagy inhibition mediated by orexin-A/OX1R.
    INTERPRETATION: This study provided the evidence that orexin-A/OX1R participated in modulating mTOR/p70S6K1/autophagy signaling pathway to promote cortisol secretion in adrenocortical cell. The findings suggest the mechanistic basis for disorders of cortisol secretion, providing the potential therapeutic targets for hypercortisolism treatment. FUND: This work was supported by National Natural Science Foundation of China (32170603, 31871286), the Doctoral Start-up Foundation of Liaoning Province (20180540008, 2019-BS-298), the Natural Science Foundation of Liaoning Province (2019-ZD-0779), and Shenyang Science and Technology Plan Fund Projects (21-173-9-28).
    Keywords:  Adrenocortical cell; Autophagy; Cortisol; Orexin-A; mTOR
    DOI:  https://doi.org/10.1016/j.bbadis.2023.166844
  62. Mol Biol Cell. 2023 Aug 16. mbcE23050168
    Temporal control of contact site formation reveals a relationship between mitochondrial division and Num1-mediated mitochondrial tethering.
    Clare S Harper, Jason C Casler, Laura L Lackner.
      Mitochondrial division is critical for maintenance of mitochondrial morphology and cellular homeostasis. Previous work has suggested that the mitochondria-ER-cortex anchor (MECA), a tripartite membrane contact site between mitochondria, the ER, and the plasma membrane, is involved in mitochondrial division. However, its role is poorly understood. We developed a system to control MECA formation and depletion, which allowed us to investigate the relationship between MECA-mediated contact sites and mitochondrial division. Num1 is the protein that mediates mitochondria-ER-plasma membrane tethering at MECA sites. Using both rapamycin-inducible dimerization and auxin-inducible degradation components coupled with Num1, we developed systems to temporally control the formation and depletion of the native contact site. Additionally, we designed a regulatable Num1-independant mitochondria-PM tether. We found that mitochondria-PM tethering alone is not sufficient to rescue mitochondrial division and that a specific feature of Num1-mediated tethering is required. This study demonstrates the utility of systems that regulate contact site formation and depletion in studying the biological functions of membrane contact sites. [Media: see text] [Media: see text].
    DOI:  https://doi.org/10.1091/mbc.E23-05-0168
  63. bioRxiv. 2023 Aug 03. pii: 2023.08.01.551382. [Epub ahead of print]
    Lysosomal release of amino acids at ER three-way junctions regulates transmembrane and secretory protein mRNA translation.
    Heejun Choi, Ya-Cheng Liao, Young J Yoon, Jonathan Grimm, Luke D Lavis, Robert H Singer, Jennifer Lippincott-Schwartz.
      One-third of the mammalian proteome is comprised of transmembrane and secretory proteins that are synthesized on endoplasmic reticulum (ER). Here, we investigate the spatial distribution and regulation of mRNAs encoding these membrane and secretory proteins (termed "secretome" mRNAs) through live cell, single molecule tracking to directly monitor the position and translation states of secretome mRNAs on ER and their relationship to other organelles. Notably, translation of secretome mRNAs occurred preferentially near lysosomes on ER marked by the ER junction-associated protein, Lunapark. Knockdown of Lunapark reduced the extent of secretome mRNA translation without affecting translation of other mRNAs. Less secretome mRNA translation also occurred when lysosome function was perturbed by raising lysosomal pH or inhibiting lysosomal proteases. Secretome mRNA translation near lysosomes was enhanced during amino acid deprivation. Addition of the integrated stress response inhibitor, ISRIB, reversed the translation inhibition seen in Lunapark knockdown cells, implying an eIF2 dependency. Altogether, these findings uncover a novel coordination between ER and lysosomes, in which local release of amino acids and other factors from ER-associated lysosomes patterns and regulates translation of mRNAs encoding secretory and membrane proteins.
    DOI:  https://doi.org/10.1101/2023.08.01.551382
  64. Cell Rep. 2023 Aug 16. pii: S2211-1247(23)01001-X. [Epub ahead of print]42(8): 112990
    Enhancing autophagy in CD11c+ antigen-presenting cells as a therapeutic strategy for acute respiratory distress syndrome.
    Christine Quach, Doumet Georges Helou, Meng Li, Benjamin Pierre Hurrell, Emily Howard, Pedram Shafiei-Jahani, Pejman Soroosh, Jing-Hsiung James Ou, Babak Razani, Virender Rehan, Omid Akbari.
      Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are severe clinical disorders that mainly develop from viral respiratory infections, sepsis, and chest injury. Antigen-presenting cells play a pivotal role in propagating uncontrolled inflammation and injury through the excess secretion of pro-inflammatory cytokines and recruitment of immune cells. Autophagy, a homeostatic process that involves the degradation of cellular components, is involved in many processes including lung inflammation. Here, we use a polyinosinic-polycytidylic acid (poly(I:C))-induced lung injury mouse model to mimic viral-induced ALI/ARDS and show that disruption of autophagy in macrophages exacerbates lung inflammation and injury, whereas autophagy induction attenuates this process. Therefore, induction of autophagy in macrophages can be a promising therapeutic strategy in ALI/ARDS.
    Keywords:  CD11c; CP: Immunology; acute respiratory distress syndrome (ARDS); antigen-presenting cells; autophagy; lung inflammation; lung injury; poly(I:C)
    DOI:  https://doi.org/10.1016/j.celrep.2023.112990
  65. Mol Med Rep. 2023 Oct;pii: 183. [Epub ahead of print]28(4):
    Lithium prevents glucocorticoid‑induced chondrocyte autophagy: An in vitro study.
    Qiuru Wang, Wanli Zhang, Jian Hu, Chengcheng Zhao, Lijun Cai, Pengde Kang.
      Glucocorticoids can induce chondrocyte autophagy. Lithium is a classical regulator of autophagy. The present study aimed to determine whether lithium can prevent glucocorticoid‑induced chondrocyte autophagy by regulating the PI3K/AKT/mTOR signaling pathway. For this purpose, rat and human chondrocytes were treated with dexamethasone (200 µM) or dexamethasone (200 µM) combined with lithium chloride at various concentrations (0.01, 0.1, 1 and 10 mM). CYTO‑ID® autophagy fluorescence staining and transmission electron microscopy were used to detect the levels of autophagy in the chondrocytes. Reverse transcription‑quantitative PCR and western blot analysis were used to measure the expression levels of the autophagy marker, LC3B and the autophagy regulatory signaling pathway (PI3K/AKT/mTOR signaling pathways) markers, AKT and mTOR. The viability of chondrocytes was measured using the Cell Counting Kit‑8 assay. It was found that compared with that in the control group, dexamethasone induced the autophagy of chondrocytes, decreased the expression levels of AKT and mTOR, and reduced cell viability. Compared with the treatment with dexamethasone alone, lithium chloride (10 mM) + dexamethasone reduced the autophagy levels, increased the expression level of AKT and mTOR, and increased cell viability. In conclusion, the present study demonstrated that lithium can prevent glucocorticoid‑induced autophagy by activating the PI3K/AKT/mTOR signaling pathway and preventing the glucocorticoid‑induced decrease in chondrocyte viability.
    Keywords:  autophagy; chondrocytes; dexamethasone; glucocorticoid; lithium
    DOI:  https://doi.org/10.3892/mmr.2023.13070
  66. Mol Cell. 2023 Aug 17. pii: S1097-2765(23)00563-4. [Epub ahead of print]83(16): 2976-2990.e9
    E4 ubiquitin ligase promotes mitofusin turnover and mitochondrial stress response.
    Vincent Anton, Ira Buntenbroich, Tânia Simões, Mariana Joaquim, Leonie Müller, Reinhard Buettner, Margarete Odenthal, Thorsten Hoppe, Mafalda Escobar-Henriques.
      Ubiquitin-dependent control of mitochondrial dynamics is important for protein quality and neuronal integrity. Mitofusins, mitochondrial fusion factors, can integrate cellular stress through their ubiquitylation, which is carried out by multiple E3 enzymes in response to many different stimuli. However, the molecular mechanisms that enable coordinated responses are largely unknown. Here we show that yeast Ufd2, a conserved ubiquitin chain-elongating E4 enzyme, is required for mitochondrial shape adjustments. Under various stresses, Ufd2 translocates to mitochondria and triggers mitofusin ubiquitylation. This elongates ubiquitin chains on mitofusin and promotes its proteasomal degradation, leading to mitochondrial fragmentation. Ufd2 and its human homologue UBE4B also target mitofusin mutants associated with Charcot-Marie-Tooth disease, a hereditary sensory and motor neuropathy characterized by progressive loss of the peripheral nerves. This underscores the pathophysiological importance of E4-mediated ubiquitylation in neurodegeneration. In summary, we identify E4-dependent mitochondrial stress adaptation by linking various metabolic processes to mitochondrial fusion and fission dynamics.
    Keywords:  CMT2A; Cdc48/p97; E4; Fzo1; MFN2; UBE4B; Ufd2; fusion; mitochondria; mitofusin; stress; ubiquitin
    DOI:  https://doi.org/10.1016/j.molcel.2023.07.021
  67. Int J Biol Macromol. 2023 Aug 12. pii: S0141-8130(23)03224-5. [Epub ahead of print] 126328
    Molecular regulation of autophagy and suppression of protein kinases by aescin, a triterpenoid saponin impedes lung cancer cell proliferation and mobility.
    Jyoti Singh, Yusuf Hussain, Abha Meena, SuaibLuqman, Rohit Anthony Sinha.
      Lung cancer is the most common and lethal cancer worldwide, yet there are no adequate and novel medications to control this illness. Previous reports suggested the potential of protein kinases to target lung cancer by regulating autophagy. This study establishes the role of aescin, a triterpenoid saponin, in targeting protein kinases responsible for lung cancer proliferation and mobility. The experimental data revealed that aescin significantly impedes lung cancer cell proliferation by downregulating protein kinases such as AKT, mTOR, MEK, and ERK. Downregulation of AKT-mTOR may promote a string of events inducing cytotoxic autophagy-mediated apoptosis in the presence of aescin. Besides, aescin decreases mobility and invasion by downregulating HIF-1α and VEGF gene expressions. Moreover, it successfully monitors EGFR gene expression, improves lung histology, and regulates biochemical parameters in a pre-clinical DEN-induced lung cancer model. Aescin was observed to be safe and non-toxic in both in silico toxicity predictions and ex vivo erythrocyte fragility assays. Hence, this study elucidates the molecular mechanism of aescin in targeting protein kinases and suggests that it could be a safer and more viable therapeutic agent for lung cancer treatment.
    Keywords:  Aescin; Autophagy; Lung-cancer; MAPK; PI3K; Protein kinase
    DOI:  https://doi.org/10.1016/j.ijbiomac.2023.126328
  68. FASEB J. 2023 09;37(9): e23145
    Cuproptosis enhances docetaxel chemosensitivity by inhibiting autophagy via the DLAT/mTOR pathway in prostate cancer.
    Hongzhuang Wen, Changbao Qu, Zhu Wang, Haitao Gao, Wuyao Liu, Hu Wang, Hao Sun, Junfei Gu, Zhan Yang, Xiaolu Wang.
      Cuproptosis, a newly discovered programmed cell death induced by copper ions, is associated with the progression and drug resistance of various tumors. Docetaxel plays a vital role as a first-line chemotherapeutic agent for advanced prostate cancer; however, most patients end up with prostate cancer progression because of inherent or acquired resistance. Herein, we examined the role of cuproptosis in the chemotherapeutic resistance of prostate cancer to docetaxel. We treated prostate cancer cell lines with elesclomol-CuCl2 , as well as with docetaxel. We performed analyses of CCK8, colony formation tests, cell cycle flow assay, transmission electron microscopy, and mTOR signaling in treated cells, and treated a xenograft prostate cancer model with elesclomol-CuCl2 and docetaxel in vivo, and performed immunohistochemistry and Western blotting analysis in treated tumors. We found that elesclomol-CuCl2 could promote cell death and enhance chemosensitivity to docetaxel. Elesclomol-CuCl2 induced cell death and inhibited the growth of prostate cancer cells relying on copper ions-induced cuproptosis, not elesclomol. In addition, dihydrolipoamide S-acetyltransferase (DLAT) was involved in cuproptosis-enhanced drug sensitivity to docetaxel. Mechanistically, upregulated DLAT by cuproptosis inhibited autophagy, promoted G2/M phase retention of cells, and enhanced the sensitivity to docetaxel chemotherapy in vitro and in vivo via the mTOR signaling pathway. Our findings demonstrated that the cuproptosis-regulated DLAT/mTOR pathway inhibited autophagy and promoted cells in G2/M phase retention, thus enhancing the chemosensitivity to docetaxel. This discovery may provide an effective therapeutic option for treating advanced prostate cancer by inhibiting the chemotherapeutic resistance to docetaxel.
    Keywords:  autophagy; chemotherapeutic resistance; cuproptosis; docetaxel; prostate cancer
    DOI:  https://doi.org/10.1096/fj.202300980R
  69. Cell Mol Life Sci. 2023 Aug 16. 80(9): 251
    AMBRA1 phosphorylation by CDK1 and PLK1 regulates mitotic spindle orientation.
    Fiorella Faienza, Federica Polverino, Girish Rajendraprasad, Giacomo Milletti, Zehan Hu, Barbara Colella, Deborah Gargano, Flavie Strappazzon, Salvatore Rizza, Mette Vixø Vistesen, Yonglun Luo, Manuela Antonioli, Valentina Cianfanelli, Caterina Ferraina, Gian Maria Fimia, Giuseppe Filomeni, Daniela De Zio, Joern Dengjel, Marin Barisic, Giulia Guarguaglini, Sabrina Di Bartolomeo, Francesco Cecconi.
      AMBRA1 is a crucial factor for nervous system development, and its function has been mainly associated with autophagy. It has been also linked to cell proliferation control, through its ability to regulate c-Myc and D-type cyclins protein levels, thus regulating G1-S transition. However, it remains still unknown whether AMBRA1 is differentially regulated during the cell cycle, and if this pro-autophagy protein exerts a direct role in controlling mitosis too. Here we show that AMBRA1 is phosphorylated during mitosis on multiple sites by CDK1 and PLK1, two mitotic kinases. Moreover, we demonstrate that AMBRA1 phosphorylation at mitosis is required for a proper spindle function and orientation, driven by NUMA1 protein. Indeed, we show that the localization and/or dynamics of NUMA1 are strictly dependent on AMBRA1 presence, phosphorylation and binding ability. Since spindle orientation is critical for tissue morphogenesis and differentiation, our findings could account for an additional role of AMBRA1 in development and cancer ontogenesis.
    Keywords:  Cell cycle; Mitotic kinases; Mitotic spindle; NUMA1; Phosphorylation
    DOI:  https://doi.org/10.1007/s00018-023-04878-6
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