bims-auttor Biomed News
on Autophagy and mTOR
Issue of 2023‒09‒03
fifty-nine papers selected by
Viktor Korolchuk, Newcastle University
  1. Atl (atlastin) regulates mTor signaling and autophagy in Drosophila muscle through alteration of the lysosomal network.
  2. NBR1-mediated selective chloroplast autophagy is important to plant stress tolerance.
  3. Mitophagy-promoting agents and their ability to promote healthy-aging.
  4. Studying Autophagy in Microglia: Overcoming the Obstacles.
  5. Co-chaperone BAG3 enters autophagic pathway via its interaction with microtubule associated protein 1 light chain 3 beta.
  6. Lysosomal glucose sensing and glycophagy in metabolism.
  7. Phosphorylation-state dependent intraneuronal sorting of Aβ differentially impairs autophagy and the endo-lysosomal system.
  8. PINK1, Keap1, and Rtnl1 regulate selective clearance of endoplasmic reticulum during development.
  9. Hyperactivity of mTORC1 or mTORC2-dependent signaling causes epilepsy downstream of somatic PTEN loss.
  10. Mitophagy: from the dark into the spotlight.
  11. Activation of transient receptor potential vanilloid 1 ameliorates tau accumulation-induced synaptic damage and cognitive dysfunction via autophagy enhancement.
  12. Pancreatic β-cell mitophagy as an adaptive response to metabolic stress and the underlying mechanism that involves lysosomal Ca2+ release.
  13. Chaperone-mediated autophagy: Molecular mechanisms, biological functions, and diseases.
  14. Pristimerin suppresses AIM2 inflammasome by modulating AIM2-PYCARD/ASC stability via selective autophagy to alleviate tendinopathy.
  15. Autophagy, clock genes and cardiovascular disease.
  16. Glucocorticoid regulation of the mTORC1 pathway modulates CD4+ T cell responses during infection.
  17. In-vivo screening implicates endoribonuclease Regnase-1 in modulating senescence-associated lysosomal changes.
  18. Shear stress induces autophagy in Schlemm's canal cells via primary cilia-mediated SMAD2/3 signaling pathway.
  19. MARCH7-mediated ubiquitination decreases the solubility of ATG14 to inhibit autophagy.
  20. Cascade Catalytic Nanoparticles Selectively Alkalize Cancerous Lysosomes to Suppress Cancer Progression And Metastasis.
  21. The transcription factor NRF1 (NFE2L1) activates aggrephagy by inducing p62 and GABARAPL1 after proteasome inhibition to maintain proteostasis.
  22. Autophagy counters inflammation-driven glycolytic impairment in aging hematopoietic stem cells.
  23. TOR-mediated Ypt1 phosphorylation regulates autophagy initiation complex assembly.
  24. Rhes depletion promotes striatal accumulation and aggregation of mutant huntingtin in a presymptomatic HD mouse model.
  25. N-retinylidene-N-retinylethanolamine degradation in human retinal pigment epithelial cells via memantine- and ifenprodil-mediated autophagy.
  26. Trpm2 deficiency in microglia attenuates neuroinflammation during epileptogensis by upregulating autophagy via the AMPK/mTOR pathway.
  27. Enhanced BMP signaling leads to enlarged nasal cartilage formation in mice.
  28. Cell type-specific NRBF2 orchestrates autophagic flux and adult hippocampal neurogenesis in chronic stress-induced depression.
  29. Impaired mitophagy induces antimicrobial responses in macrophages infected with Mycobacterium tuberculosis.
  30. TECPR1 helps bridge the CASM during lysosome damage.
  31. Lysosomal cystine governs ferroptosis sensitivity in cancer via cysteine stress response.
  32. Regulation of autophagy by natural polyphenols in the treatment of diabetic kidney disease: therapeutic potential and mechanism.
  33. VEGF signaling governs the initiation of biliary-mediated liver regeneration through the PI3K-mTORC1 axis.
  34. Targeted Degradation of Alpha-Synuclein by Autophagosome-Anchoring Chimera Peptides.
  35. Ame-miR-980-3p participates in autophagy-mediated midgut remodelling in Apis mellifera via targeting Atg2B.
  36. Genetics, environmental stress, and amino acid supplementation affect lactational performance via mTOR signaling pathway in bovine mammary epithelial cells.
  37. TOR complex 1 negatively regulates NDR kinase Cbk1 to control cell separation in budding yeast.
  38. Autophagy may protect the brain against prolonged consequences of headache attacks: A narrative/hypothesis review.
  39. HIF-1α-PPARγ-mTORC1 signaling pathway-mediated autophagy induces inflammatory response in pancreatic cells in rats with hyperlipidemic acute pancreatitis.
  40. Cell cycle-linked vacuolar pH dynamics regulate amino acid homeostasis and cell growth.
  41. IL-17A is involved in the hyperplasia of blood vessels in local lesions of psoriasis by inhibiting autophagy.
  42. ATG2A-mediated bridge-like lipid transport regulates lipid droplet accumulation.
  43. TRPM2 protects against cisplatin-induced acute kidney injury and mitochondrial dysfunction via modulating autophagy.
  44. Astragalus Polysaccharide Protects Experimental Colitis Through An AhR-Dependent Autophagy Mechanism.
  45. Autophagy in sepsis-induced acute lung injury: Friend or foe?
  46. The stress-responsive protein REDD1 and its pathophysiological functions.
  47. Rhabdovirus encoded glycoprotein induces and harnesses host antiviral autophagy for maintaining its compatible infection.
  48. Repopulation of autophagy-deficient stromal cells with autophagy-intact cells after repeated breeding in uterine mesenchyme-specific Atg7 knockout mice.
  49. The spatiotemporal control of ER membrane fragmentation during reticulophagy.
  50. KLF2 Regulates Neural Differentiation of Dental Pulp-derived Stem Cells by Modulating Autophagy and Mitophagy.
  51. Three-dimensional growth sensitizes breast cancer cells to treatment with ferroptosis-promoting drugs.
  52. Selective autophagy associated with iron overload aggravates non-alcoholic steatohepatitis via ferroptosis.
  53. UPS writes a new saga of SAGA.
  54. Targeted inhibition of mTOR by BML-275 induces mitochondrial-mediated apoptosis and autophagy in prostate cancer.
  55. Fluorescence polarisation activity-based protein profiling for the identification of deoxynojirimycin-type inhibitors selective for lysosomal retaining alpha- and beta-glucosidases.
  56. Endoplasmic reticulum stress-mediated autophagy alleviates lipopolysaccharide-induced nucleus pulposus cell pyroptosis by inhibiting CHOP signaling in vitro.
  57. Dysregulation of mTOR by tau in Alzheimer's disease.
  58. Hsa_circ_0000585 promotes chemoresistance to cis-platin in epithelial cells of ovarian cancer by modulating autophagy.
  59. Plk1 promotes renal tubulointerstitial fibrosis by targeting autophagy/lysosome axis.
  1. Autophagy. 2023 Aug 30. 1-20
    Atl (atlastin) regulates mTor signaling and autophagy in Drosophila muscle through alteration of the lysosomal network.
    Saurabh Srivastav, Kevin van der Graaf, Pratibha Singh, Alloysius Budi Utama, Matthew D Meyer, James A McNew, Michael Stern.
      ABBREVIATIONS: atl atlastin; ALR autophagic lysosome reformation; ER endoplasmic reticulum; GFP green fluorescent protein; HSP hereditary spastic paraplegia; Lamp1 lysosomal associated membrane protein 1 PolyUB polyubiquitin; RFP red fluorescent protein; spin spinster; mTor mechanistic Target of rapamycin; VCP valosin containing protein.
    Keywords:  ATG8; Hereditary Spastic Paraplegia; LAMP1; Neurodegeneration; endosome; protein aggregates; rab7
    DOI:  https://doi.org/10.1080/15548627.2023.2249794
  2. Autophagy. 2023 Aug 27. 1-2
    NBR1-mediated selective chloroplast autophagy is important to plant stress tolerance.
    Hui Zhang, Qihua Ling.
      Macroautophagy/autophagy is a conserved process in eukaryotes responsible for degrading unwanted or damaged macromolecules and organelles through the lysosome or vacuole for recycling and reutilization. Our previous studies revealed the degradation of chloroplast proteins through a pathway dependent on the ubiquitin proteasome system, known as CHLORAD. Recently, we demonstrated a role for selective autophagy in regulating chloroplast protein import and enhancing stress tolerance in plants. Specifically, we found that K63-ubiquitination of TOC components at the chloroplast outer envelope membrane is recognized by the selective autophagy adaptor NBR1, leading to the degradation of TOC proteins under UV-B irradiation and heat stresses in Arabidopsis. This process was shown to control chloroplast protein import and influence photosynthetic activity. Based on our results, we have, for the first time, demonstrated that selective autophagy plays a vital role in chloroplast protein degradation, specifically in response to certain abiotic stresses.
    Keywords:  Arabidopsis thaliana; NBR1; chloroplast; protein import; selective autophagy
    DOI:  https://doi.org/10.1080/15548627.2023.2251324
  3. Biochem Soc Trans. 2023 Aug 31. pii: BST20221363. [Epub ahead of print]
    Mitophagy-promoting agents and their ability to promote healthy-aging.
    Vijigisha Srivastava, Einav Gross.
      The removal of damaged mitochondrial components through a process called mitochondrial autophagy (mitophagy) is essential for the proper function of the mitochondrial network. Hence, mitophagy is vital for the health of all aerobic animals, including humans. Unfortunately, mitophagy declines with age. Many age-associated diseases, including Alzheimer's and Parkinson's, are characterized by the accumulation of damaged mitochondria and oxidative damage. Therefore, activating the mitophagy process with small molecules is an emerging strategy for treating multiple aging diseases. Recent studies have identified natural and synthetic compounds that promote mitophagy and lifespan. This article aims to summarize the existing knowledge about these substances. For readers' convenience, the knowledge is presented in a table that indicates the chemical data of each substance and its effect on lifespan. The impact on healthspan and the molecular mechanism is reported if known. The article explores the potential of utilizing a combination of mitophagy-inducing drugs within a therapeutic framework and addresses the associated challenges of this strategy. Finally, we discuss the process that balances mitophagy, i.e. mitochondrial biogenesis. In this process, new mitochondrial components are generated to replace the ones cleared by mitophagy. Furthermore, some mitophagy-inducing substances activate biogenesis (e.g. resveratrol and metformin). Finally, we discuss the possibility of combining mitophagy and biogenesis enhancers for future treatment. In conclusion, this article provides an up-to-date source of information about natural and synthetic substances that activate mitophagy and, hopefully, stimulates new hypotheses and studies that promote healthy human aging worldwide.
    Keywords:  aging; lifespan; mitochondria; mitochondrial autophagy; mitochondrial biogenesis; mitophagy
    DOI:  https://doi.org/10.1042/BST20221363
  4. Methods Mol Biol. 2024 ;2713 45-70
    Studying Autophagy in Microglia: Overcoming the Obstacles.
    Ainhoa Plaza-Zabala, Amanda Sierra.
      In this chapter, we provide an overview of the main techniques and experimental approaches that can be used to analyze autophagy flux in microglia, the brain-resident macrophages. For this purpose, we first briefly introduce the main peculiarities of microglial biology, describe the basic mechanisms and functions of autophagy, and summarize the evidence accumulated so far on the role of autophagy in the regulation of microglial survival and functions, mainly phagocytosis and inflammation. Then, we highlight conceptual and technical aspects of autophagic recycling and microglial physiology that need to be taken into account for the accurate evaluation of autophagy flux in microglia. Finally, we describe the main assays that can be used to analyze the complete sequence of autophagosome formation and degradation or autophagy flux, mainly in cultured microglia and in vivo. The main approaches include indirect tracking of autophagosomes by autophagic enzymes such as LC3 by western blot and fluorescence-based confocal microscopy, as well as direct analysis of autophagic vesicles by electron microscopy. We also discuss the advantages and disadvantages of using these methods in specific experimental contexts and highlight the need to complement LC3 and/or electron microscopy data with analysis of other autophagic effectors and lysosomal proteins that participate in the initiation and completion of autophagy flux, respectively. In summary, we provide an experimental guide for the analysis of autophagosome turnover in microglia, emphasizing the need to combine as many markers and complementary approaches as possible to fully characterize the status of autophagy flux in microglia.
    Keywords:  Autophagosomes; Autophagy flux; Confocal microscopy; Electron microscopy; Lysosomes; Microglia; Western blot
    DOI:  https://doi.org/10.1007/978-1-0716-3437-0_3
  5. Traffic. 2023 Sep 01.
    Co-chaperone BAG3 enters autophagic pathway via its interaction with microtubule associated protein 1 light chain 3 beta.
    Hagen Körschgen, Marius Baeken, Daniel Schmitt, Heike Nagel, Christian Behl.
      The co-chaperone BAG3 is a hub for a variety of cellular pathways via its multiple domains and its interaction with chaperones of the HSP70 family or small HSPs. During aging and under cellular stress conditions in particular, BAG3, together with molecular chaperones, ensures the sequestration of aggregated or aggregation-prone ubiquitinated proteins to the autophagic-lysosomal system via ubiquitin receptors. Accumulating evidence for BAG3-mediated selective autophagy independent of cargo ubiquitination led to analyses predicting a direct interaction of BAG3 with LC3 proteins. Phylogenetically, BAG3 comprises several highly conserved potential LIRs, LC3-interacting regions, which might allow for the direct targeting of BAG3 including its cargo to autophagosomes and drive their autophagic degradation. Based on pull-down experiments, peptide arrays and proximity ligation assays, our results provide evidence of an interaction of BAG3 with LC3B. In addition, we could demonstrate that disabling all predicted LIRs abolished the inducibility of a colocalization of BAG3 with LC3B-positive structures and resulted in a substantial decrease of BAG3 levels within purified native autophagic vesicles compared with wild-type BAG3. These results suggest an autophagic targeting of BAG3 via interaction with LC3B. Therefore, we conclude that, in addition to being a key co-chaperone to HSP70, BAG3 may also act as a cargo receptor for client proteins, which would significantly extend the role of BAG3 in selective macroautophagy and protein quality control.
    Keywords:  BAG3; BAG3-mediated autophagy; Bcl2-associated athanogene 3; LC3; LIR
    DOI:  https://doi.org/10.1111/tra.12916
  6. Trends Endocrinol Metab. 2023 Aug 24. pii: S1043-2760(23)00152-2. [Epub ahead of print]
    Lysosomal glucose sensing and glycophagy in metabolism.
    Melina C Mancini, Robert C Noland, J Jason Collier, Susan J Burke, Krisztian Stadler, Timothy D Heden.
      Lysosomes are cellular organelles that function to catabolize both extra- and intracellular cargo, act as a platform for nutrient sensing, and represent a core signaling node integrating bioenergetic cues to changes in cellular metabolism. Although lysosomal amino acid and lipid sensing in metabolism has been well characterized, lysosomal glucose sensing and the role of lysosomes in glucose metabolism is unrefined. This review will highlight the role of the lysosome in glucose metabolism with a focus on lysosomal glucose and glycogen sensing, glycophagy, and lysosomal glucose transport and how these processes impact autophagy and energy metabolism. Additionally, the role of lysosomal glucose metabolism in genetic and metabolic diseases will be briefly discussed.
    Keywords:  autophagy; carbohydrate sensing; glycogen; nutrient sensing
    DOI:  https://doi.org/10.1016/j.tem.2023.07.008
  7. Autophagy. 2023 Aug 29.
    Phosphorylation-state dependent intraneuronal sorting of Aβ differentially impairs autophagy and the endo-lysosomal system.
    Akshay Kapadia, Sandra Theil, Sabine Opitz, Nàdia Villacampa, Hannes Beckert, Susanne Schoch-McGovern, Michael T Heneka, Sathish Kumar, Jochen Walter.
      Progressive accumulation of amyloid-β (Aβ) aggregates in extracellular plaques is a characteristic hallmark of Alzheimer disease (AD). Aβ is also found in intraneuronal deposits and associated with alterations of the endo-lysosomal system and impairment of macroautophagy/autophagy. Here, we assessed the effect of Aβ phosphorylation on neuronal autophagy and the endo-lysosomal pathway. Analysis of APP-PSEN1dE9 transgenic mice revealed a phosphorylation-state dependent intraneuronal accumulation of Aβ species in endo-lysosomal and autophagy-related compartments. Cell biological studies further demonstrate a differential uptake and sorting of phosphorylated Aβ variants in cultured neurons, and phosphorylation-state specific effects of Aβ variants on neuronal autophagy and lysosomal function. While Aβ phosphorylated at serine residue 8 accumulated in autophagosomes, Aβ phosphorylated at serine residue 26 showed efficient transport to lysosomes. The selective sorting of phosphorylated Aβ species caused differential impairment of vesicular transport and lysosomal function associated with neurotoxicity. Thus, the relative occurrence of phosphorylated Aβ species and their intraneuronal accumulation could contribute to AD pathogenesis, and to the commonly observed aberrations of the vesicular transport system already at the early stages of the disease.
    Keywords:  Alzheimer’s disease; Post-translationally modified Aβ; autophagic flux; neurodegeneration; phosphorylated Aβ; vesicular trafficking
    DOI:  https://doi.org/10.1080/15548627.2023.2252300
  8. Cell. 2023 Aug 21. pii: S0092-8674(23)00862-0. [Epub ahead of print]
    PINK1, Keap1, and Rtnl1 regulate selective clearance of endoplasmic reticulum during development.
    Ruoxi Wang, Tina M Fortier, Fei Chai, Guangyan Miao, James L Shen, Lucas J Restrepo, Jeromy J DiGiacomo, Panagiotis D Velentzas, Eric H Baehrecke.
      Selective clearance of organelles, including endoplasmic reticulum (ER) and mitochondria, by autophagy plays an important role in cell health. Here, we describe a developmentally programmed selective ER clearance by autophagy. We show that Parkinson's disease-associated PINK1, as well as Atl, Rtnl1, and Trp1 receptors, regulate ER clearance by autophagy. The E3 ubiquitin ligase Parkin functions downstream of PINK1 and is required for mitochondrial clearance while having the opposite function in ER clearance. By contrast, Keap1 and the E3 ubiquitin ligase Cullin3 function downstream of PINK1 to regulate ER clearance by influencing Rtnl1 and Atl. PINK1 regulates a change in Keap1 localization and Keap1-dependent ubiquitylation of the ER-phagy receptor Rtnl1 to facilitate ER clearance. Thus, PINK1 regulates the selective clearance of ER and mitochondria by influencing the balance of Keap1- and Parkin-dependent ubiquitylation of substrates that determine which organelle is removed by autophagy.
    Keywords:  Drosophila; ER-phagy; Keap1; PINK1; Parkin; Rtnl1
    DOI:  https://doi.org/10.1016/j.cell.2023.08.008
  9. bioRxiv. 2023 Aug 19. pii: 2023.08.18.553856. [Epub ahead of print]
    Hyperactivity of mTORC1 or mTORC2-dependent signaling causes epilepsy downstream of somatic PTEN loss.
    Erin R Cullen, Isabelle Mittelstadt, Matthew C Weston.
      Gene variants that hyperactivate PI3K-mTOR signaling in the brain lead to epilepsy and cortical malformations in humans. Some gene variants associated with these pathologies only hyperactivate mTORC1, but others, such as PTEN, PIC3CA , and AKT , hyperactivate both mTORC1- and mTORC2-dependent signaling. Previous work has established a key role for mTORC1 hyperactivity in mTORopathies, however, whether mTORC2 hyperactivity contributes is not clear. To test this, we inactivated mTORC1 and/or mTORC2 downstream of early Pten deletion in a new model of somatic Pten LOF in the cortex. Spontaneous seizures and epileptiform activity persisted despite mTORC1 or mTORC2 inactivation alone, but inactivating both mTORC1 and mTORC2 normalized pathology. These results suggest that hyperactivity of both mTORC1 and mTORC2 are sufficient to cause epilepsy, and that targeted therapies should aim to reduce activity of both complexes.
    DOI:  https://doi.org/10.1101/2023.08.18.553856
  10. Mol Plant. 2023 Aug 31. pii: S1674-2052(23)00250-2. [Epub ahead of print]
    Mitophagy: from the dark into the spotlight.
    Vivian Schmitt, Olivier Van Aken.
      Despite the generally placid appearance of plants, many dynamic processes take place inside a plant cell. One such process that has garnered attention in recent years is termed 'autophagy'. While originally discovered in yeast, our understanding of autophagy in plants has improved significantly. Autophagy is considered a cellular recycling system in which cellular components or even entire organelles can be encapsulated by a membrane structure (autophagosome) and then transported to the vacuole (in plants) for degradation and re-use. One example of components degraded by autophagy are the mitochondria ('mitophagy'). Only a few years ago there was almost no information about plant mitophagy available, but lately several important studies have been published. A recent study identified an ATG8-FLZ-SnRK1 regulatory axis that connects carbon starvation signaling to mitophagy. In this Spotlight article, we focus on the function of mitochondrial FLZ proteins and SnRK1, and discuss them in context of current knowledge on the regulation of mitophagy in plants.
    DOI:  https://doi.org/10.1016/j.molp.2023.08.015
  11. CNS Neurosci Ther. 2023 Aug 29.
    Activation of transient receptor potential vanilloid 1 ameliorates tau accumulation-induced synaptic damage and cognitive dysfunction via autophagy enhancement.
    Tao Zhang, Yuan Tian, Xiaoqing Zheng, Ruomeng Li, Li Hu, Xindong Shui, Yingxue Mei, Quling Wang, Mi Zhang, Xiuzhi Zheng, Long Wang, Dongmei Chen, Wucheng Tao, Tae Ho Lee.
      AIMS: The autophagy-lysosomal pathway is important for maintaining cellular proteostasis, while dysfunction of this pathway has been suggested to drive the aberrant intraneuronal accumulation of tau protein, leading to synaptic damage and cognitive impairment. Previous studies have demonstrated that the activation of transient receptor potential vanilloid 1 (TRPV1) by capsaicin has a positive impact on cognition and AD-related biomarkers. However, the effect and mechanism of TPRV1 activation on neuronal tau homeostasis remain elusive.METHODS: A mouse model of tauopathy was established by overexpressing full-length human tau in the CA3 area. Mice were fed capsaicin diet (0.0125%) or normal diet for 9 weeks. The cognitive ability, synaptic function, tau phosphorylation levels, and autophagy markers were detected. In vitro, capsaicin-induced alterations in cellular autophagy and tau degradation were characterized using two cell models. Besides, various inhibitors were applied to validate the role of TRPV1-mediated autophagy enhancement in tau clearance.
    RESULTS: We observed that TRPV1 activation by capsaicin effectively mitigates hippocampal tau accumulation-induced synaptic damages, gliosis, and cognitive impairment in vivo. Capsaicin promotes the degradation of abnormally accumulated tau through enhancing autophagic function in neurons, which is dependent on TRPV1-mediated activation of AMP-activated protein kinase (AMPK) and subsequent inhibition of the mammalian target of rapamycin (mTOR). Blocking AMPK activation abolishes capsaicin-induced autophagy enhancement and tau degradation in neurons.
    CONCLUSION: Our findings reveal that capsaicin-induced TRPV1 activation confers neuroprotection by restoring neuronal tau homeostasis via modulating cellular autophagy and provides additional evidence to support the potential of TRPV1 as a therapeutic target for tauopathies.
    Keywords:  autophagy; capsaicin; cognition; tau; tauopathy; transient receptor potential vanilloid 1
    DOI:  https://doi.org/10.1111/cns.14432
  12. Exp Mol Med. 2023 Sep 01.
    Pancreatic β-cell mitophagy as an adaptive response to metabolic stress and the underlying mechanism that involves lysosomal Ca2+ release.
    Soo-Jin Oh, Kihyoun Park, Seong Keun Sonn, Goo Taeg Oh, Myung-Shik Lee.
      Mitophagy is an excellent example of selective autophagy that eliminates damaged or dysfunctional mitochondria, and it is crucial for the maintenance of mitochondrial integrity and function. The critical roles of autophagy in pancreatic β-cell structure and function have been clearly shown. Furthermore, morphological abnormalities and decreased function of mitochondria have been observed in autophagy-deficient β-cells, suggesting the importance of β-cell mitophagy. However, the role of authentic mitophagy in β-cell function has not been clearly demonstrated, as mice with pancreatic β-cell-specific disruption of Parkin, one of the most important players in mitophagy, did not exhibit apparent abnormalities in β-cell function or glucose homeostasis. Instead, the role of mitophagy in pancreatic β-cells has been investigated using β-cell-specific Tfeb-knockout mice (TfebΔβ-cell mice); Tfeb is a master regulator of lysosomal biogenesis or autophagy gene expression and participates in mitophagy. TfebΔβ-cell mice were unable to adaptively increase mitophagy or mitochondrial complex activity in response to high-fat diet (HFD)-induced metabolic stress. Consequently, TfebΔβ-cell mice exhibited impaired β-cell responses and further exacerbated metabolic deterioration after HFD feeding. TFEB was activated by mitochondrial or metabolic stress-induced lysosomal Ca2+ release, which led to calcineurin activation and mitophagy. After lysosomal Ca2+ release, depleted lysosomal Ca2+ stores were replenished by ER Ca2+ through ER→lysosomal Ca2+ refilling, which supplemented the low lysosomal Ca2+ capacity. The importance of mitophagy in β-cell function was also demonstrated in mice that developed β-cell dysfunction and glucose intolerance after treatment with a calcineurin inhibitor that hampered TFEB activation and mitophagy.
    DOI:  https://doi.org/10.1038/s12276-023-01055-4
  13. MedComm (2020). 2023 Oct;4(5): e347
    Chaperone-mediated autophagy: Molecular mechanisms, biological functions, and diseases.
    Ruchen Yao, Jun Shen.
      Chaperone-mediated autophagy (CMA) is a lysosomal degradation pathway that eliminates substrate proteins through heat-shock cognate protein 70 recognition and lysosome-associated membrane protein type 2A-assisted translocation. It is distinct from macroautophagy and microautophagy. In recent years, the regulatory mechanisms of CMA have been gradually enriched, including the newly discovered NRF2 and p38-TFEB signaling, as positive and negative regulatory pathways of CMA, respectively. Normal CMA activity is involved in the regulation of metabolism, aging, immunity, cell cycle, and other physiological processes, while CMA dysfunction may be involved in the occurrence of neurodegenerative disorders, tumors, intestinal disorders, atherosclerosis, and so on, which provides potential targets for the treatment and prediction of related diseases. This article describes the general process of CMA and its role in physiological activities and summarizes the connection between CMA and macroautophagy. In addition, human diseases that concern the dysfunction or protective role of CMA are discussed. Our review deepens the understanding of the mechanisms and physiological functions of CMA and provides a summary of past CMA research and a vision of future directions.
    Keywords:  carcinoma; chaperone‐mediated autophagy; neurodegenerative disorders; signaling regulation; therapeutic potential
    DOI:  https://doi.org/10.1002/mco2.347
  14. Autophagy. 2023 Aug 30. 1-18
    Pristimerin suppresses AIM2 inflammasome by modulating AIM2-PYCARD/ASC stability via selective autophagy to alleviate tendinopathy.
    Huaji Jiang, Yingchao Xie, Jiansen Lu, Hongyu Li, Ke Zeng, Zhiqiang Hu, Dan Wu, Jianwu Yang, Zhenxia Yao, Huadan Chen, Xiaoqian Gong, Xiao Yu.
      Macroautophagy/autophagy plays an important role in regulating cellular homeostasis and influences the pathogenesis of degenerative diseases. Tendinopathy is characterized by tendon degeneration and inflammation. However, little is known about the role of selective autophagy in tendinopathy. Here, we find that pristimerin (PM), a quinone methide triterpenoid, is more effective in treating tendinopathy than the first-line drug indomethacin. PM inhibits the AIM2 inflammasome and alleviates inflammation during tendinopathy by promoting the autophagic degradation of AIM2 through a PYCARD/ASC-dependent manner. A mechanistic study shows that PM enhances the K63-linked ubiquitin chains of PYCARD/ASC at K158/161, which serves as a recognition signal for SQSTM1/p62-mediated autophagic degradation of the AIM2-PYCARD/ASC complex. We further identify that PM binds the Cys53 site of deubiquitinase USP50 through the Michael-acceptor and blocks the binding of USP50 to PYCARD/ASC, thereby reducing USP50-mediated cleavage of K63-linked ubiquitin chains of PYCARD/ASC. Finally, PM treatment in vivo generates an effect comparable to inflammasome deficiency in alleviating tendinopathy. Taken together, these findings demonstrate that PM alleviates the progression of tendinopathy by modulating AIM2-PYCARD/ASC stability via SQSTM1/p62-mediated selective autophagic degradation, thus providing a promising autophagy-based therapeutic for tendinopathy.Abbreviations: 3-MA: 3-methyladenine; AIM2: absent in melanoma 2; AT: Achilles tenotomy; ATP: adenosine triphosphate; BMDMs: bone marrow-derived macrophages; CHX: cycloheximide; Col3a1: collagen, type III, alpha 1; CQ: chloroquine; Cys: cysteine; DARTS: drug affinity responsive target stability; DTT: dithiothreitol; DUB: deubiquitinase; gDNA: genomic DNA; GSH: glutathione; His: histidine; IL1B/IL-1β: interleukin 1 beta; IND: indomethacin; IP: immunoprecipitation; LPS: lipopolysaccharide; MMP: mitochondrial membrane potential; NLRP3: NLR family, pyrin domain containing 3; PM: pristimerin; PYCARD/ASC: PYD and CARD domain containing; SN: supernatants; SOX9: SRY (sex determining region Y)-box 9; SQSTM1: sequestosome 1; Tgfb: transforming growth factor, beta; TIMP3: tissue inhibitor of metalloproteinase 3; TNMD: tenomodulin; TRAF6: TNF receptor-associated factor 6; Ub: ubiquitin; USP50: ubiquitin specific peptidase 50; WCL: whole cell lysates.
    Keywords:  AIM2; USP50; pristimerin; selective autophagy; tendinopathy
    DOI:  https://doi.org/10.1080/15548627.2023.2249392
  15. Can J Cardiol. 2023 Aug 29. pii: S0828-282X(23)01639-2. [Epub ahead of print]
    Autophagy, clock genes and cardiovascular disease.
    Inna Rabinovich-Nikitin, Eryn Kirshenbaum, Lorrie A Kirshenbaum.
      Circadian rhythms are 24-hour cycles that regulate physical, mental, and behavioral changes of most living organisms. In the heart, circadian rhythms regulate processes such as heart rate, blood pressure, blood coagulability and vascular tone. However, in addition to regulating physiological processes, circadian rhythms also regulate pathophysiological processes in the heart. In this regard, circadian rhythms regulate the onset, severity and outcome of many cardiovascular disease (CVD), including myocardial infarction, diabetic cardiomyopathy, doxorubicin-induced cardiotoxicity and heart failure. Notably, the underlying mechanism of many of these diseases is linked to impaired cellular quality control processes, such as autophagy. Autophagy is a homeostatic cellular process that regulates the removal of damaged cellular components, and allowing their degradation and recycling into their basic constituents for production of cellular energy. Many studies from recent years point to a regulatory link between autophagy and circadian machinery in the control of CVDs. In this review, we highlight the recent discoveries in the field of circadian induced autophagy in the heart and provide the molecular mechanisms and signaling pathways that underlie the crosstalk between autophagy and clock gene control in response to cardiac injury. Understanding the mechanisms that underlie circadian induced autophagy in response to cardiac stress may prove beneficial in developing novel therapeutic approaches to treat cardiac disease.
    Keywords:  Autophagy; cardiovascular disease; circadian rhythm; mitochondria
    DOI:  https://doi.org/10.1016/j.cjca.2023.08.022
  16. Clin Transl Immunology. 2023 ;12(8): e1464
    Glucocorticoid regulation of the mTORC1 pathway modulates CD4+ T cell responses during infection.
    Huihui Chen, Zhiwen Liu, Jie Zha, Li Zeng, Runyan Tang, Chengyuan Tang, Juan Cai, Chongqing Tan, Hong Liu, Zheng Dong, Guochun Chen.
      Objectives: Conventional glucocorticoid (GC) treatment poses significant risks for opportunistic infections due to its suppressive impact on CD4+ T cells. This study aimed to explore the mechanisms by which GCs modulate the functionality of CD4+ T cells during infection.Methods: We consistently measured FOXP3, inflammatory cytokines and phospho-S6 ribosomal protein levels in CD4+ T cells from patients undergoing conventional GC treatment. Using Foxp3EGFP animals, we investigated the dynamic activation of the mechanistic target of rapamycin complex 1 (mTORC1) pathway and its correlation with the immunoregulatory function of CD4+ T cells under the influence of GCs.
    Results: GCs dynamically altered the expression pattern of FOXP3 in CD4+ T cells, promoting their acquisition of an active T regulatory (Treg) cell phenotype upon stimulation. Mechanistically, GCs undermined the kinetics of the mTORC1 pathway, which was closely correlated with phenotype conversion and functional properties of CD4+ T cells. Dynamic activation of the mTORC1 signaling modified the GC-dampened immunoregulatory capacity of CD4+ T cells by phenotypically and functionally bolstering the FOXP3+ Treg cells. Interventions targeting the mTORC1 pathway effectively modulated the GC-dampened immunoregulatory capacity of CD4+ T cells.
    Conclusion: These findings highlight a novel mTORC1-mediated mechanism underlying CD4+ T cell immunity in the context of conventional GC treatment.
    Keywords:  FOXP3; T cell; glucocorticoid; immunomodulation; inflammation; mTOR complex 1
    DOI:  https://doi.org/10.1002/cti2.1464
  17. Geroscience. 2023 Aug 29.
    In-vivo screening implicates endoribonuclease Regnase-1 in modulating senescence-associated lysosomal changes.
    Richard Venz, Anita Goyala, Abel Soto-Gamez, Tugce Yenice, Marco Demaria, Collin Y Ewald.
      Accumulation of senescent cells accelerates aging and age-related diseases, whereas preventing this accumulation extends the lifespan in mice. A characteristic of senescent cells is increased staining with β-galactosidase (β-gal) ex vivo. Here, we describe a progressive accumulation of β-gal staining in the model organism C. elegans during aging. We show that distinct pharmacological and genetic interventions targeting the mitochondria and the mTORC1 to the nuclear core complex axis, the non-canonical apoptotic, and lysosomal-autophagy pathways slow the age-dependent accumulation of β-gal. We identify a novel gene, rege-1/Regnase-1/ZC3H12A/MCPIP1, modulating β-gal staining via the transcription factor ets-4/SPDEF. We demonstrate that knocking down Regnase-1 in human cell culture prevents senescence-associated β-gal accumulation. Our data provide a screening pipeline to identify genes and drugs modulating senescence-associated lysosomal phenotypes.
    Keywords:  Beta-gal; Longevity; Metformin; Senescence; Senolytic
    DOI:  https://doi.org/10.1007/s11357-023-00909-z
  18. Autophagy Rep. 2023 ;pii: 2236519. [Epub ahead of print]2(1):
    Shear stress induces autophagy in Schlemm's canal cells via primary cilia-mediated SMAD2/3 signaling pathway.
    Myoung Sup Shim, Angela Dixon, April Nettesheim, Kristin M Perkumas, W Daniel Stamer, Yang Sun, Paloma B Liton.
      The Schlemm's canal (SC) is a circular, lymphatic-like vessel located at the limbus of the eye that participates in the regulation of aqueous humor drainage to control intraocular pressure (IOP). Circumferential flow of aqueous humor within the SC lumen generates shear stress, which regulates SC cell behaviour. Using biochemical analysis and real-time live cell imaging techniques, we have investigated the activation of autophagy in SC cells by shear stress. We report, for the first time, the primary cilium (PC)-dependent activation of autophagy in SC cells in response to shear stress. Moreover, we identified PC-dependent shear stress-induced autophagy to be positively regulated by phosphorylation of SMAD2 in its linker and C-terminal regions. Additionally, SMAD2/3 signaling was found to transcriptionally activate LC3B, ATG5 and ATG7 in SC cells. Intriguingly, concomitant to SMAD2-dependent activation of autophagy, we also report here the activation of mTOR pathway, a classical autophagy inhibitor, in SC cells by shear stress. mTOR activation was found to also be dependent on the PC. Moreover, pharmacological inhibition of class I PI3K increased phosphorylation of SMAD2 at the linker and activated autophagy. Together, our data indicates an interplay between PI3K and SMAD2/3 signaling pathways in the regulation of PC-dependent shear stress-induced autophagy in SC cells.
    Keywords:  SMAD2/3; Schlemm’s canal; autophagy; glaucoma; mTOR; primary cilia; shear stress
    DOI:  https://doi.org/10.1080/27694127.2023.2236519
  19. Cell Rep. 2023 Aug 25. pii: S2211-1247(23)01056-2. [Epub ahead of print]42(9): 113045
    MARCH7-mediated ubiquitination decreases the solubility of ATG14 to inhibit autophagy.
    Xue Shi, Wenfeng Wu, Zhenhuan Feng, Peiyang Fan, Ruona Shi, Xiaofei Zhang.
      Autophagy is a fundamental biological process critical to all eukaryotic cellular life. Although autophagy has been increasingly studied, how its process is precisely coordinated remains an open question. ATG14 (ATG14L/Barkor) is known to play a crucial role in both autophagosome formation and autophagosome-lysosome fusion. However, how ATG14 is regulated, especially at the post-translation level, is still not clear. Here, we report that MARCH7 (membrane-associated ring-CH-type finger 7), an E3 ubiquitin ligase, inhibits autophagy by ubiquitinating ATG14. MARCH7 significantly promotes K6-, K11-, and K63-linked mixed polyubiquitination on ATG14, triggering the aggregation of ATG14 and reducing its solubility in cells. Functionally, we find that MARCH7 depletion decreases the number of aggresome-like induced structures (ALISs). Mechanistically, we show that ubiquitinated ATG14 has fewer interactions with STX17, leading to the inhibition of autophagy flux. Collectively, our study reveals a mechanism in regulating autophagy and suggests a potential strategy for the treatment of autophagy-related diseases.
    Keywords:  CP: Cell biology
    DOI:  https://doi.org/10.1016/j.celrep.2023.113045
  20. Adv Mater. 2023 Aug 29. e2305394
    Cascade Catalytic Nanoparticles Selectively Alkalize Cancerous Lysosomes to Suppress Cancer Progression And Metastasis.
    Limin Pan, Haibao Peng, Bowon Lee, Jiaxu Zhao, Xiulian Shen, Ximei Yan, Yipeng Hua, Jeonghyun Kim, Dokyoon Kim, Mouhong Lin, Shengjian Zhang, Xiaohui Li, Xueying Yi, Feibai Yao, Zhiyong Qin, Jiulin Du, Yudan Chi, Jwa-Min Nam, Taeghwan Hyeon, Jianan Liu.
      Lysosomes are critical in modulating the progression and metastasis for various cancers. There is currently an unmet need for lysosomal alkalizers that can selectively and safely alter the pH and inhibit the function of cancer lysosomes. Here we report an effective, selective, and safe lysosomal alkalizer that can inhibit autophagy and suppress tumors in mice. Our lysosomal alkalizer consists of an Fex Oy core that generates hydroxyl radicals (•OH) in the presence of excessive H+ and H2 O2 inside cancer lysosomes and CeO2-z satellites that capture and convert •OH into hydroxide ions (OH- ). Alkalized lysosomes, which display impaired enzyme activity and autophagy, lead to cancer cell apoptosis. We show that our alkalizer effectively inhibited both local and systemic tumor growth and metastasis in mice. Our work demonstrates that the intrinsic properties of nanoparticles can be harnessed to build effective lysosomal alkalizers that are both selective and safe. This article is protected by copyright. All rights reserved.
    Keywords:  autophagy; lysosome alkalization; metastasis; nanoparticles; tumor therapy
    DOI:  https://doi.org/10.1002/adma.202305394
  21. Sci Rep. 2023 Sep 01. 13(1): 14405
    The transcription factor NRF1 (NFE2L1) activates aggrephagy by inducing p62 and GABARAPL1 after proteasome inhibition to maintain proteostasis.
    Atsushi Hatanaka, Sota Nakada, Gen Matsumoto, Katsuya Satoh, Iori Aketa, Akira Watanabe, Tomoaki Hirakawa, Tadayuki Tsujita, Tsuyoshi Waku, Akira Kobayashi.
      The ubiquitin‒proteasome system (UPS) and autophagy are the two primary cellular pathways of misfolded or damaged protein degradation that maintain cellular proteostasis. When the proteasome is dysfunctional, cells compensate for impaired protein clearance by activating aggrephagy, a type of selective autophagy, to eliminate ubiquitinated protein aggregates; however, the molecular mechanisms by which impaired proteasome function activates aggrephagy remain poorly understood. Here, we demonstrate that activation of aggrephagy is transcriptionally induced by the transcription factor NRF1 (NFE2L1) in response to proteasome dysfunction. Although NRF1 has been previously shown to induce the expression of proteasome genes after proteasome inhibition (i.e., the proteasome bounce-back response), our genome-wide transcriptome analyses identified autophagy-related p62/SQSTM1 and GABARAPL1 as genes directly targeted by NRF1. Intriguingly, NRF1 was also found to be indispensable for the formation of p62-positive puncta and their colocalization with ULK1 and TBK1, which play roles in p62 activation via phosphorylation. Consistently, NRF1 knockdown substantially reduced the phosphorylation rate of Ser403 in p62. Finally, NRF1 selectively upregulated the expression of GABARAPL1, an ATG8 family gene, to induce the clearance of ubiquitinated proteins. Our findings highlight the discovery of an activation mechanism underlying NRF1-mediated aggrephagy through gene regulation when proteasome activity is impaired.
    DOI:  https://doi.org/10.1038/s41598-023-41492-9
  22. bioRxiv. 2023 Aug 19. pii: 2023.08.17.553736. [Epub ahead of print]
    Autophagy counters inflammation-driven glycolytic impairment in aging hematopoietic stem cells.
    Paul V Dellorusso, Melissa A Proven, Fernando J Calero-Nieto, Xiaonan Wang, Carl A Mitchell, Felix Hartmann, Meelad Amouzgar, Patricia Favaro, Andrew DeVilbiss, James W Swann, Theodore T Ho, Zhiyu Zhao, Sean C Bendall, Sean Morrison, Berthold Göttgens, Emmanuelle Passegué.
      Aging of the hematopoietic system promotes various blood, immune and systemic disorders and is largely driven by hematopoietic stem cell (HSC) dysfunction ( 1 ). Autophagy is central for the benefits associated with activation of longevity signaling programs ( 2 ), and for HSC function and response to nutrient stress ( 3,4 ). With age, a subset of HSCs increases autophagy flux and preserves some regenerative capacity, while the rest fail to engage autophagy and become metabolically overactivated and dysfunctional ( 4 ). However, the signals that promote autophagy in old HSCs and the mechanisms responsible for the increased regenerative potential of autophagy-activated old HSCs remain unknown. Here, we demonstrate that autophagy activation is an adaptive survival response to chronic inflammation in the aging bone marrow (BM) niche ( 5 ). We find that inflammation impairs glucose metabolism and suppresses glycolysis in aged HSCs through Socs3-mediated impairment of AKT/FoxO-dependent signaling. In this context, we show that inflammation-mediated autophagy engagement preserves functional quiescence by enabling metabolic adaptation to glycolytic impairment. Moreover, we demonstrate that transient autophagy induction via a short-term fasting/refeeding paradigm normalizes glucose uptake and glycolytic flux and significantly improves old HSC regenerative potential. Our results identify inflammation-driven glucose hypometabolism as a key driver of HSC dysfunction with age and establish autophagy as a targetable node to reset old HSC glycolytic and regenerative capacity.One-Sentence Summary: Autophagy compensates for chronic inflammation-induced metabolic deregulation in old HSCs, and its transient modulation can reset old HSC glycolytic and regenerative capacity.
    DOI:  https://doi.org/10.1101/2023.08.17.553736
  23. EMBO J. 2023 Aug 28. e112814
    TOR-mediated Ypt1 phosphorylation regulates autophagy initiation complex assembly.
    Weijing Yao, Yuting Chen, Yingcong Chen, Pengwei Zhao, Jing Liu, Yi Zhang, Qiang Jiang, Choufei Wu, Yu Xie, Siyu Fan, Miao Ye, Yigang Wang, Yuyao Feng, Xue Bai, Mingzhu Fan, Shan Feng, Juan Wang, Yixian Cui, Hongguang Xia, Cheng Ma, Zhiping Xie, Liqin Zhang, Qiming Sun, Wei Liu, Cong Yi.
      The regulation of autophagy initiation is a key step in autophagosome biogenesis. However, our understanding of the molecular mechanisms underlying the stepwise assembly of ATG proteins during this process remains incomplete. The Rab GTPase Ypt1/Rab1 is recognized as an essential autophagy regulator. Here, we identify Atg23 and Atg17 as binding partners of Ypt1, with their direct interaction proving crucial for the stepwise assembly of autophagy initiation complexes. Disruption of Ypt1-Atg23 binding results in significantly reduced Atg9 interactions with Atg11, Atg13, and Atg17, thus preventing the recruitment of Atg9 vesicles to the phagophore assembly site (PAS). Likewise, Ypt1-Atg17 binding contributes to the PAS recruitment of Ypt1 and Atg1. Importantly, we found that Ypt1 is phosphorylated by TOR at the Ser174 residue. Converting this residue to alanine blocks Ypt1 phosphorylation by TOR and enhances autophagy. Conversely, the Ypt1S174D phosphorylation mimic impairs both PAS recruitment and activation of Atg1, thus inhibiting subsequent autophagy. Thus, we propose TOR-mediated Ypt1 as a multifunctional assembly factor that controls autophagy initiation via its regulation of the stepwise assembly of ATG proteins.
    Keywords:  ATG proteins; TOR; Ypt1; autophagy; stepwise assembly
    DOI:  https://doi.org/10.15252/embj.2022112814
  24. Front Aging Neurosci. 2023 ;15 1237018
    Rhes depletion promotes striatal accumulation and aggregation of mutant huntingtin in a presymptomatic HD mouse model.
    Yongcheng Pan, Beisha Tang, Xiao-Jiang Li, Shihua Li, Qiong Liu.
      Introduction: Huntington's disease (HD) is caused by CAG trinucleotide repeats in the HTT gene. Selective neurodegeneration in the striatum is prominent in HD, despite widespread expression of mutant HTT (mHTT). Ras homolog enriched in the striatum (Rhes) is a GTP-binding protein enriched in the striatum, involved in dopamine-related behaviors and autophagy regulation. Growing evidence suggests Rhes plays a critical role in the selective striatal degeneration in HD, but its specific function in this context remains complex and controversial.Methods: In this study, we utilized CRISPR/Cas9 to knockdown Rhes at different disease stages through adeno-associated virus (AAV) transduction in HD knock-in (KI) mice. Immunoblotting and immunofluorescence were employed to assess the impact of Rhes depletion on mHTT levels, neuronal loss, astrogliosis and autophagy activity.
    Results: Rhes depletion in 22-week-old HD KI mice (representing the presymptomatic stage) led to mHTT accumulation, reduced neuronal cell staining, and increased astrogliosis. However, no such effects were observed in 36-week-old HD KI mice (representing the symptomatic stage). Additionally, Rhes deletion in 22-week-old HD KI mice resulted in increased P62 levels, reduced LC3-II levels, and unchanged phosphorylation of mTOR and beclin-1, unchanged mTOR protein level, except for a decrease in beclin-1.
    Discussion: Our findings suggest that knockdown Rhes promotes striatal aggregation of mutant huntingtin by reducing autophagy activity in a mTOR-independent manner. Rhes plays a protective role during the presymptomatic stage of HD KI mice.
    Keywords:  Huntington’s disease; Rhes; gene targeting; mHTT aggregates; neurodegeneration
    DOI:  https://doi.org/10.3389/fnagi.2023.1237018
  25. Korean J Physiol Pharmacol. 2023 Sep 01. 27(5): 449-456
    N-retinylidene-N-retinylethanolamine degradation in human retinal pigment epithelial cells via memantine- and ifenprodil-mediated autophagy.
    Jae Rim Lee, Kwang Won Jeong.
      N-methyl-D-aspartate (NMDA) receptors are ionic glutamine receptors involved in brain development and functions such as learning and memory formation. NMDA receptor inhibition is associated with autophagy activation. In this study, we investigated whether the NMDA receptor antagonists, memantine and ifenprodil, induce autophagy in human retinal pigment epithelial cells (ARPE-19) to remove Nretinylidene- N-retinylethanolamine (A2E), an intracellular lipofuscin component. Fluorometric analysis using labeled A2E (A2E-BDP) and confocal microscopic examination revealed that low concentrations of NMDA receptor antagonists, which did not induce cytotoxicity, significantly reduced A2E accumulation in ARPE-19 cells. In addition, memantine and ifenprodil activated autophagy in ARPE-19 cells as measured by microtubule-associated protein 1A/1B-light chain3-II formation and phosphorylated p62 protein levels. Further, to understand the correlation between memantine- and ifenprodil-mediated A2E degradation and autophagy, autophagy-related 5 (ATG5) was depleted using RNA interference. Memantine and ifenprodil failed to degrade A2E in ARPE-19 cells lacking ATG5. Taken together, our study indicates that the NMDA receptor antagonists, memantine and ifenprodil, can remove A2E accumulated in cells via autophagy activation in ARPE-19 cells.
    Keywords:  A2E; ARPE-19; Autophagy; Ifenprodil; Memantine
    DOI:  https://doi.org/10.4196/kjpp.2023.27.5.449
  26. Neurobiol Dis. 2023 Aug 28. pii: S0969-9961(23)00288-7. [Epub ahead of print] 106273
    Trpm2 deficiency in microglia attenuates neuroinflammation during epileptogensis by upregulating autophagy via the AMPK/mTOR pathway.
    Chen Chen, Tao Zhu, Lifen Gong, Zhe Hu, Hao Wei, Jianchen Fan, Donghui Lin, Xiaojun Wang, Junyu Xu, Xinyan Dong, Yifan Wang, Ningxiao Xia, Linghui Zeng, Peifang Jiang, Yicheng Xie.
      Epilepsy is one of the most common neurological disorders. Neuroinflammation involving the activation of microglia and astrocytes constitutes an important and common mechanism in epileptogenesis. Transient receptor potential melastatin 2 (TRPM2) is a calcium-permeable, non-selective cation channel that plays pathological roles in various inflammation-related diseases. Our previous study demonstrated that Trpm2 knockout exhibits therapeutic effects on pilocarpine-induced glial activation and neuroinflammation. However, whether TRPM2 in microglia and astrocytes plays a common pathogenic role in this process and the underlying molecular mechanisms remained undetermined. Here, we demonstrate a previously unknown role for microglial TRPM2 in epileptogensis. Trpm2 knockout in microglia attenuated kainic acid (KA)-induced glial activation, inflammatory cytokines production and hippocampal paroxysmal discharges, whereas Trpm2 knockout in astrocytes exhibited no significant effects. Furthermore, we discovered that these therapeutic effects were mediated by upregulated autophagy via the adenosine monophosphate activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway in microglia. Thus, our findings highlight an important deleterious role of microglial TRPM2 in temporal lobe epilepsy.
    Keywords:  AMPK/mTOR pathway; Astrocytes; Autophagy; Epileptogensis; Microglia; Neuroinflammation; Transient receptor potential melastatin 2
    DOI:  https://doi.org/10.1016/j.nbd.2023.106273
  27. Biochem Biophys Res Commun. 2023 Aug 23. pii: S0006-291X(23)00999-3. [Epub ahead of print]678 173-178
    Enhanced BMP signaling leads to enlarged nasal cartilage formation in mice.
    Hiroyuki Yamaguchi, Sowmya Swaminathan, Yuji Mishina, Yoshihiro Komatsu.
      Bone morphogenetic proteins (BMPs) are required for craniofacial bone development. However, it remains elusive how BMP signaling regulates craniofacial cartilage development. To address this question, we utilized a genetic system to enhance BMP signaling via one of BMP type I receptors ALK2 in a chondrocyte-specific manner (hereafter Ca-Alk2:Col2-Cre) in mice. Ca-Alk2:Col2-Cre mice died shortly after birth due to severe craniofacial abnormalities including cleft palate, defective tongue, and shorter mandible formation. Histological analysis revealed that these phenotypes were attributed to the extensive chondrogenesis. Compared with controls, enhanced SOX9 and RUNX2 production were observed in nasal cartilage of Ca-Alk2:Col2-Cre mice. To reveal the mechanisms responsible for enlarged nasal cartilage, we examined Smad-dependent and Smad-independent BMP signaling pathways. While the Smad-independent BMP signaling pathway including p38, ERK, and JNK remained silent, the Smad1/5/9 was highly phosphorylated in Ca-Alk2:Col2-Cre mice. Interestingly, Ca-Alk2:Col2-Cre mice showed enhanced S6 kinase phosphorylation, a readout of mammalian target of rapamycin complex 1 (mTORC1). These findings may suggest that enhanced Smad-dependent BMP signaling positively regulates the mTOR pathway and stimulates chondrocytes toward hypertrophic differentiation, thereby leading to enlarged nasal cartilage formation in mice.
    Keywords:  ALK2; BMP signaling; Craniofacial cartilage; Mouse; mTORC1
    DOI:  https://doi.org/10.1016/j.bbrc.2023.08.053
  28. Cell Discov. 2023 Aug 29. 9(1): 90
    Cell type-specific NRBF2 orchestrates autophagic flux and adult hippocampal neurogenesis in chronic stress-induced depression.
    Shao-Qi Zhang, Qiao Deng, Qi Zhu, Zhuang-Li Hu, Li-Hong Long, Peng-Fei Wu, Jin-Gang He, Hong-Sheng Chen, Zhenyu Yue, Jia-Hong Lu, Fang Wang, Jian-Guo Chen.
      Dysfunctional autophagy and impairment of adult hippocampal neurogenesis (AHN) each contribute to the pathogenesis of major depressive disorder (MDD). However, whether dysfunctional autophagy is linked to aberrant AHN underlying MDD remains unclear. Here we demonstrate that the expression of nuclear receptor binding factor 2 (NRBF2), a component of autophagy-associated PIK3C3/VPS34-containing phosphatidylinositol 3-kinase complex, is attenuated in the dentate gyrus (DG) under chronic stress. NRBF2 deficiency inhibits the activity of the VPS34 complex and impairs autophagic flux in adult neural stem cells (aNSCs). Moreover, loss of NRBF2 disrupts the neurogenesis-related protein network and causes exhaustion of aNSC pool, leading to the depression-like phenotype. Strikingly, overexpressing NRBF2 in aNSCs of the DG is sufficient to rescue impaired AHN and depression-like phenotype of mice. Our findings reveal a significant role of NRBF2-dependent autophagy in preventing chronic stress-induced AHN impairment and suggest the therapeutic potential of targeting NRBF2 in MDD treatment.
    DOI:  https://doi.org/10.1038/s41421-023-00583-7
  29. Cell Biosci. 2023 Aug 30. 13(1): 158
    Impaired mitophagy induces antimicrobial responses in macrophages infected with Mycobacterium tuberculosis.
    Junghwan Lee, Seong-Ahn Lee, Sang-Hun Son, Ji-Ae Choi, Tam Doan Nguyen, Jaewhan Kim, Doyi Son, Chang-Hwa Song.
      BACKGROUND: Mitophagy, mitochondrial selective autophagy, plays a pivotal role in the maintenance of cellular homeostasis in response to cellular stress. However, the role of mitophagy in macrophages during infection has not been elucidated. To determine whether mitophagy regulates intracellular pathogen survival, macrophages were infected with Mycobacterium tuberculosis (Mtb), an intracellular bacterium.RESULTS: We showed that Mtb-infected macrophages induced mitophagy through BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 (BNIP3) activation. In contrast, BNIP3-deficient macrophages failed to induce mitophagy, resulting in reduced mitochondrial membrane potential in response to Mtb infection. Moreover, the accumulation of damaged mitochondria due to BNIP3 deficiency generated higher levels of mitochondrial reactive oxygen species (mROS) compared to the control, suppressing the intracellular survival of Mtb. We observed that siBNIP3 suppressed intracellular Mtb in mice lungs.
    CONCLUSION: We found that BNIP3 plays a critical role in the regulation of mitophagy during Mtb infection. The inhibition of mitophagy suppresses Mtb growth in macrophages through increased mROS production. Therefore, BNIP3 might be a novel therapeutic target for tuberculosis treatment.
    Keywords:  BNIP3; Macrophage; Mitophagy; Mycobacterium tuberculosis; mROS
    DOI:  https://doi.org/10.1186/s13578-023-01107-2
  30. EMBO J. 2023 Aug 28. e115210
    TECPR1 helps bridge the CASM during lysosome damage.
    Oliver Florey.
      Maintaining the integrity of the endolysosomal system is of great importance for cellular homeostasis. Recent work published in The EMBO Journal and EMBO Reports reveals a novel role for the protein TECPR1 as a sensor for stressed membranes and regulator of lysosomal membrane repair.
    DOI:  https://doi.org/10.15252/embj.2023115210
  31. Mol Cell. 2023 Aug 24. pii: S1097-2765(23)00640-8. [Epub ahead of print]
    Lysosomal cystine governs ferroptosis sensitivity in cancer via cysteine stress response.
    Robert V Swanda, Quanquan Ji, Xincheng Wu, Jingyue Yan, Leiming Dong, Yuanhui Mao, Saori Uematsu, Yizhou Dong, Shu-Bing Qian.
      The amino acid cysteine and its oxidized dimeric form cystine are commonly believed to be synonymous in metabolic functions. Cyst(e)ine depletion not only induces amino acid response but also triggers ferroptosis, a non-apoptotic cell death. Here, we report that unlike general amino acid starvation, cyst(e)ine deprivation triggers ATF4 induction at the transcriptional level. Unexpectedly, it is the shortage of lysosomal cystine, but not the cytosolic cysteine, that elicits the adaptative ATF4 response. The lysosome-nucleus signaling pathway involves the aryl hydrocarbon receptor (AhR) that senses lysosomal cystine via the kynurenine pathway. A blockade of lysosomal cystine efflux attenuates ATF4 induction and sensitizes ferroptosis. To potentiate ferroptosis in cancer, we develop a synthetic mRNA reagent, CysRx, that converts cytosolic cysteine to lysosomal cystine. CysRx maximizes cancer cell ferroptosis and effectively suppresses tumor growth in vivo. Thus, intracellular nutrient reprogramming has the potential to induce selective ferroptosis in cancer without systematic starvation.
    Keywords:  AhR; cancer therapy; cysteine; cystine; ferroptosis; lysosome; mRNA; nutrient stress
    DOI:  https://doi.org/10.1016/j.molcel.2023.08.004
  32. Front Endocrinol (Lausanne). 2023 ;14 1142276
    Regulation of autophagy by natural polyphenols in the treatment of diabetic kidney disease: therapeutic potential and mechanism.
    Tongtong Liu, Qi Jin, Liping Yang, Huimin Mao, Fang Ma, Yuyang Wang, Ping Li, Yongli Zhan.
      Diabetic kidney disease (DKD) is a major microvascular complication of diabetes and a leading cause of end-stage renal disease worldwide. Autophagy plays an important role in maintaining cellular homeostasis in renal physiology. In DKD, the accumulation of advanced glycation end products induces decreased renal autophagy-related protein expression and transcription factor EB (TFEB) nuclear transfer, leading to impaired autophagy and lysosomal function and blockage of autophagic flux. This accelerates renal resident cell injury and apoptosis, mediates macrophage infiltration and phenotypic changes, ultimately leading to aggravated proteinuria and fibrosis in DKD. Natural polyphenols show promise in treating DKD by regulating autophagy and promoting nuclear transfer of TFEB and lysosomal repair. This review summarizes the characteristics of autophagy in DKD, and the potential application and mechanisms of some known natural polyphenols as autophagy regulators in DKD, with the goal of contributing to a deeper understanding of natural polyphenol mechanisms in the treatment of DKD and promoting the development of their applications. Finally, we point out the limitations of polyphenols in current DKD research and provide an outlook for their future research.
    Keywords:  autophagy; diabetic kidney disease; lysosome; natural polyphenols; transcription factor EB
    DOI:  https://doi.org/10.3389/fendo.2023.1142276
  33. Cell Rep. 2023 Aug 24. pii: S2211-1247(23)01039-2. [Epub ahead of print]42(9): 113028
    VEGF signaling governs the initiation of biliary-mediated liver regeneration through the PI3K-mTORC1 axis.
    Pengcheng Cai, Rui Ni, Mengzhu Lv, Huijuan Liu, Jieqiong Zhao, Jianbo He, Lingfei Luo.
      Biliary epithelial cells (BECs) are a potential source to repair the damaged liver when hepatocyte proliferation is compromised. Promotion of BEC-to-hepatocyte transdifferentiation could be beneficial to the clinical therapeutics of patients with end-stage liver diseases. However, mechanisms underlying the initiation of BEC transdifferentiation remain largely unknown. Here, we show that upon extreme hepatocyte injury, vegfaa and vegfr2/kdrl are notably induced in hepatic stellate cells and BECs, respectively. Pharmacological and genetic inactivation of vascular endothelial growth factor (VEGF) signaling would disrupt BEC dedifferentiation and proliferation, thus restraining hepatocyte regeneration. Mechanically, VEGF signaling regulates the activation of the PI3K-mammalian target of rapamycin complex 1 (mTORC1) axis, which is essential for BEC-to-hepatocyte transdifferentiation. In mice, VEGF signaling exerts conserved roles in oval cell activation and BEC-to-hepatocyte differentiation. Taken together, this study shows VEGF signaling as an initiator of biliary-mediated liver regeneration through activating the PI3K-mTORC1 axis. Modulation of VEGF signaling in BECs could be a therapeutic approach for patients with end-stage liver diseases.
    Keywords:  CP: Cell biology
    DOI:  https://doi.org/10.1016/j.celrep.2023.113028
  34. J Med Chem. 2023 Aug 31.
    Targeted Degradation of Alpha-Synuclein by Autophagosome-Anchoring Chimera Peptides.
    Yichen Tong, Wentao Zhu, Jian Chen, Wenqian Zhang, Fang Xu, Jiyan Pang.
      Targeted protein degradation (TPD) confers knockdown of "undruggable" targets such as alpha-synuclein (αSyn), a pathogenic protein in multiple neurodegenerative diseases. Though many of these proteins were mainly degraded through the autophagy-lysosome pathway (ALP), few TPD tools harnessing the ALP were reported. Herein, we developed a strategy termed autophagosome-anchoring chimera (ATACC), in which the protein of interest (POI) can be anchored to microtubule-associated protein-1 light chain-3B (LC3B) on the autophagosome with the assistance of an LC3-interacting region (LIR)-containing bifunctional peptide, and the selective autophagy of the POI is thus facilitated. A series of αSyn-targeting ATACC peptides were designed and synthesized. Biological evaluations demonstrated that these compounds could degrade αSyn specifically and effectively through a "chemical-induced cargo recognition-ALP degradation" mechanism. The neuroprotective effects of ATACC peptide P1 were further validated in vitro and in vivo. Collectively, our results provided a new TPD tool and revealed a potential therapeutic strategy against synucleinopathies.
    DOI:  https://doi.org/10.1021/acs.jmedchem.3c01303
  35. Insect Mol Biol. 2023 Sep 02.
    Ame-miR-980-3p participates in autophagy-mediated midgut remodelling in Apis mellifera via targeting Atg2B.
    Wen-Feng Chen, Xue-Peng Chi, Hong-Yu Song, Hong-Fang Wang, Ying Wang, Zhen-Guo Liu, Bao-Hua Xu.
      Autophagy is a process that serves to degrade damaged proteins and organelles, thereby promoting cell homeostasis, differentiation, development and survival. Many miRNAs have been found to have regulatory roles in autophagy. In insects, it has been shown that autophagy is involved in hormone-regulated programmed cell death during metamorphic midgut remodelling. However, whether this is also true during the remodelling of the honey bee midgut is unclear. In the present study, we explored the relationship between autophagy and midgut remodelling and sought to identify miRNAs involved in this physiological process. We found that autophagy occurred during midgut remodelling and that the inhibition of autophagy resulted in midgut dysplasia in prepupae. Differentially expressed miRNAs enriched in the autophagy signalling pathway during midgut remodelling were identified by small RNA-seq. Ame-miR-980-3p, which targets the autophagy-related gene Atg2B, was screened out. Furthermore, abnormal expression of ame-miR-980-3p in the pupal stage led to the thinning of the midgut wall of newly emerged bees (NE). When ame-miR-980-3p expression was inhibited, the intestinal villi of NE bees became significantly shorter and sparse, and the lipid signal in the peritrophic matrix of Pb almost disappeared, indicating that the adult midgut was underdeveloped and the lipid absorption ability was weakened. Taken together, ame-miR-980-3p targeted Atg2B to participate in the regulation of midgut autophagy in the pupae, and the abnormal expression of ame-miR-980-3p would interfere with cell proliferation and death in the process of midgut remodelling, hinder the formation of adult midgut and eventually lead to adult midgut dysplasia and affect the lipid absorption function of the midgut in Apis mellifera.
    Keywords:  Atg2B; ame-miR-980-3p; autophagy; honey bee; midgut remodelling
    DOI:  https://doi.org/10.1111/imb.12869
  36. Front Genet. 2023 ;14 1195774
    Genetics, environmental stress, and amino acid supplementation affect lactational performance via mTOR signaling pathway in bovine mammary epithelial cells.
    Bin Li, Muhammad Zahoor Khan, Ibrar Muhammad Khan, Qudrat Ullah, Zhuo-Ma Cisang, Nan Zhang, Dan Wu, Bingjian Huang, Yulin Ma, Adnan Khan, Nan Jiang, Muhammad Zahoor.
      Mammary glands are known for their ability to convert nutrients present in the blood into milk contents. In cows, milk synthesis and the proliferation of cow mammary epithelial cells (CMECs) are regulated by various factors, including nutrients such as amino acids and glucose, hormones, and environmental stress. Amino acids, in particular, play a crucial role in regulating cell proliferation and casein synthesis in mammalian epithelial cells, apart from being building blocks for protein synthesis. Studies have shown that environmental factors, particularly heat stress, can negatively impact milk production performance in dairy cattle. The mammalian target of rapamycin complex 1 (mTORC1) pathway is considered the primary signaling pathway involved in regulating cell proliferation and milk protein and fat synthesis in cow mammary epithelial cells in response to amino acids and heat stress. Given the significant role played by the mTORC signaling pathway in milk synthesis and cell proliferation, this article briefly discusses the main regulatory genes, the impact of amino acids and heat stress on milk production performance, and the regulation of mTORC signaling pathway in cow mammary epithelial cells.
    Keywords:  amino acids; cow mammary epithelial cells; environmental stress; mTORC1 signaling pathway; milk production
    DOI:  https://doi.org/10.3389/fgene.2023.1195774
  37. PLoS Biol. 2023 Aug;21(8): e3002263
    TOR complex 1 negatively regulates NDR kinase Cbk1 to control cell separation in budding yeast.
    Magdalena Foltman, Iván Mendez, Joan J Bech-Serra, Carolina de la Torre, Jennifer L Brace, Eric L Weiss, María Lucas, Ethel Queralt, Alberto Sanchez-Diaz.
      The target of rapamycin (TOR) signalling pathway plays a key role in the coordination between cellular growth and the cell cycle machinery in eukaryotes. The underlying molecular mechanisms by which TOR might regulate events after anaphase remain unknown. We show for the first time that one of the 2 TOR complexes in budding yeast, TORC1, blocks the separation of cells following cytokinesis by phosphorylation of a member of the NDR (nuclear Dbf2-related) protein-kinase family, the protein Cbk1. We observe that TORC1 alters the phosphorylation pattern of Cbk1 and we identify a residue within Cbk1 activation loop, T574, for which a phosphomimetic substitution makes Cbk1 catalytically inactive and, indeed, reproduces TORC1 control over cell separation. In addition, we identify the exocyst component Sec3 as a key substrate of Cbk1, since Sec3 activates the SNARE complex to promote membrane fusion. TORC1 activity ultimately compromises the interaction between Sec3 and a t-SNARE component. Our data indicate that TORC1 negatively regulates cell separation in budding yeast by participating in Cbk1 phosphorylation, which in turn controls the fusion of secretory vesicles transporting hydrolase at the site of division.
    DOI:  https://doi.org/10.1371/journal.pbio.3002263
  38. Headache. 2023 Aug 28.
    Autophagy may protect the brain against prolonged consequences of headache attacks: A narrative/hypothesis review.
    Michal Fila, Elzbieta Pawlowska, Joanna Szczepanska, Janusz Blasiak.
      OBJECTIVE: To assess the potential of autophagy in migraine pathogenesis.BACKGROUND: The interplay between neurons and microglial cells is important in migraine pathogenesis. Migraine-related effects, such as cortical spreading depolarization and release of calcitonin gene-related peptide, may initiate adenosine triphosphate (ATP)-mediating pro-nociceptive signaling in the meninges causing headaches. Such signaling may be induced by the interaction of ATP with purinergic receptor P2X 7 (P2X7R) on microglial cells leading to a Ca2+ -mediated pH increase in lysosomes and release of autolysosome-like vehicles from microglial cells indicating autophagy impairment.
    METHODS: A search in PubMed was conducted with the use of the terms "migraine," "autophagy," "microglia," and "degradation" in different combinations.
    RESULTS: Impaired autophagy in microglia may activate secretory autophagy and release of specific proteins, including brain-derived neurotrophic factor (BDNF), which can be also released through the pores induced by P2X7R activation in microglial cells. BDNF may be likewise released from microglial cells upon ATP- and Ca2+ -mediated activation of another purinergic receptor, P2X4R. BDNF released from microglia might induce autophagy in neurons to clear cellular debris produced by oxidative stress, which is induced in the brain as the response to migraine-related energy deficit. Therefore, migraine-related signaling may impair degradative autophagy, stimulate secretory autophagy in microglia, and degradative autophagy in neurons. These effects are mediated by purinergic receptors P2X4R and P2X7R, BDNF, ATP, and Ca2+ .
    CONCLUSION: Different effects of migraine-related events on degradative autophagy in microglia and neurons may prevent prolonged changes in the brain related to headache attacks.
    Keywords:  BDNF; P2X4R; P2X7R; autophagy; microglia; migraine
    DOI:  https://doi.org/10.1111/head.14625
  39. Mol Biol Rep. 2023 Aug 29.
    HIF-1α-PPARγ-mTORC1 signaling pathway-mediated autophagy induces inflammatory response in pancreatic cells in rats with hyperlipidemic acute pancreatitis.
    Yumei Ma, Xiaolin Li, Zhilan Liu, Xiaohong Xue, Yaping Wang, Yingcai Ma.
      OBJECTIVE: The incidence of hyperlipidemic acute pancreatitis (HLAP) has rapidly increased in recent years in China. Autophagy has been implicated in the inflammatory response of pancreatic cells in HLAP, but the molecular mechanisms remain unclear.METHODS: In this study, the role of HIF-1α-PPARγ-mTORC1 pathway-mediated autophagy in the inflammatory response of pancreatic cells and the underlying molecular mechanism were investigated in a rat model of HLAP using immunohistochemistry, ELISA, electron microscopy, and western blot analysis.
    RESULTS: The results revealed that autophagy was significantly increased and pancreatic injury was exacerbated in HLAP rats, and the inflammatory response was further exacerbated by treatment with rapamycin but relieved by treatment with 3-MA. Hyperlipidemia induced upregulation of HIF-1α and downregulation of PPARγ, which in turn led to an increase in autophagy and consequently exacerbation of the inflammatory response of pancreatic cells.
    CONCLUSIONS: HIF-1α-PPARγ-mTORC1 pathway-mediated autophagy plays a critical role in the inflammatory response of pancreatic cells in HLAP, and interference with the HIF-1α-PPARγ-mTOR pathway can serve as a new strategy for the prevention and treatment of HLAP.
    Keywords:  Autophagy; HIF-1α; Hyperlipidemic acute pancreatitis; Inflammatory response; PPARγ; mTORC1
    DOI:  https://doi.org/10.1007/s11033-023-08639-3
  40. Nat Metab. 2023 Aug 28.
    Cell cycle-linked vacuolar pH dynamics regulate amino acid homeostasis and cell growth.
    Voytek Okreglak, Rachel Ling, Maria Ingaramo, Nathaniel H Thayer, Alfred Millett-Sikking, Daniel E Gottschling.
      Amino acid homeostasis is critical for many cellular processes. It is well established that amino acids are compartmentalized using pH gradients generated between organelles and the cytoplasm; however, the dynamics of this partitioning has not been explored. Here we develop a highly sensitive pH reporter and find that the major amino acid storage compartment in Saccharomyces cerevisiae, the lysosome-like vacuole, alkalinizes before cell division and re-acidifies as cells divide. The vacuolar pH dynamics require the uptake of extracellular amino acids and activity of TORC1, the v-ATPase and the cycling of the vacuolar specific lipid phosphatidylinositol 3,5-bisphosphate, which is regulated by the cyclin-dependent kinase Pho85 (CDK5 in mammals). Vacuolar pH regulation enables amino acid sequestration and mobilization from the organelle, which is important for mitochondrial function, ribosome homeostasis and cell size control. Collectively, our data provide a new paradigm for the use of dynamic pH-dependent amino acid compartmentalization during cell growth/division.
    DOI:  https://doi.org/10.1038/s42255-023-00872-1
  41. J Cosmet Dermatol. 2023 Aug 27.
    IL-17A is involved in the hyperplasia of blood vessels in local lesions of psoriasis by inhibiting autophagy.
    Juanjuan Wang, Ling Zhou, Hui Hou, Jiao Li, Xincheng Zhao, Jiajie Li, Junqin Li, Xuping Niu, Ruixia Hou, Kaiming Zhang.
      OBJECTIVE: Increased angiogenesis is a pathological feature of psoriasis, but the pathomechanisms of angiogenesis in psoriasis are not clear. Interleukin-17A (IL-17A) is the major effect factor in the pathogenesis of psoriasis. Our results showed that IL-17A can promote angiogenesis and cause endothelial cell inflammation. Autophagy plays an important role not only in regulating inflammation, but also in regulating angiogenesis. Whether angiogenesis in psoriasis is related to autophagy remains unclear. In this study, we treated human umbilical vein endothelial cells (HUVECs) with IL-17A to simulate increased angiogenesis to study whether increased angiogenesis in psoriasis is related to autophagy.METHODS AND RESULTS: Our results showed that treatment of HUVECs with IL-17A significantly increased angiogenesis and expression levels of mRNA for multiple proinflammatory cytokines (CCL20, IL-8, CCL2, IL-6, and IL-1β) and, while decreasing intracellular levels of nitric oxide (NO) and NO synthase (NOS) activity. Moreover, IL-17A inhibited autophagy as shown that IL-17A significantly increased expression levels of LC3II and p62 proteins. Induction of autophagy ameliorated IL-17A-mediated inflammatory response and inhibited angiogenesis, accompanied by increased p-AMPKα(Thr172) and p-ULK1(Ser555) expression, and decreased p-mTOR(Ser2448) and p-ULK1(Ser757) expression. Furthermore, inhibition of either AMPK or lysosomal acidification completely overrode autophagy-induced changes in angiogenesis and NOS activity. Finally, induction of autophagy decreased apoptosis and caspase-3 activity in IL-17A-treated HUVECs.
    CONCLUSIONS: These results showed that IL-17A is involved in angiogenesis and inflammatory response by inhibiting autophagy through AMPK signaling pathway, suggesting that autophagy may be a new therapeutic target for psoriasis.
    Keywords:  AMPK; IL-17A; angiogenesis; autophagy; inflammation
    DOI:  https://doi.org/10.1111/jocd.15975
  42. bioRxiv. 2023 Aug 14. pii: 2023.08.14.553257. [Epub ahead of print]
    ATG2A-mediated bridge-like lipid transport regulates lipid droplet accumulation.
    Justin L Korfhage, Neng Wan, Helin Elhan, Lisa Kauffman, Mia Pineda, Devin M Fuller, Abdou Rachid Thiam, Karin M Reinisch, Thomas J Melia.
      ATG2 proteins facilitate bulk lipid transport between membranes. ATG2 is an essential autophagy protein, but ATG2 also localizes to lipid droplets (LDs), and genetic depletion of ATG2 increases LD numbers while impairing fatty acid transport from LDs to mitochondria. How ATG2 supports LD homeostasis and whether lipid transport regulates this homeostasis remains unknown. Here we demonstrate that ATG2 is preferentially recruited to phospholipid monolayers such as those surrounding LDs rather than to phospholipid bilayers. In vitro , ATG2 can drive phospholipid transport from artificial LDs with rates that correlate with the binding affinities, such that phospholipids are moved much more efficiently when one of the ATG2-interacting structures is an artificial LD. ATG2 is thought to exhibit 'bridge-like" lipid transport, with lipids flowing across the protein between membranes. We mutated key amino acids within the bridge to form a transport-dead ATG2 mutant (TD-ATG2A) which we show specifically blocks bridge-like, but not shuttle-like, lipid transport in vitro . TD-ATG2A still localizes to LDs, but is unable to rescue LD accumulation in ATG2 knockout cells. Thus, ATG2 has a natural affinity for, and an enhanced activity upon LD surfaces and uses bridge-like lipid transport to support LD dynamics in cells.
    DOI:  https://doi.org/10.1101/2023.08.14.553257
  43. Theranostics. 2023 ;13(13): 4356-4375
    TRPM2 protects against cisplatin-induced acute kidney injury and mitochondrial dysfunction via modulating autophagy.
    Binfeng Yu, Lini Jin, Xi Yao, Yi Zhang, Gensheng Zhang, Fangqin Wang, Xinwan Su, Qiuyuan Fang, Liang Xiao, Yi Yang, Lin-Hua Jiang, Jianghua Chen, Wei Yang, Weiqiang Lin, Fei Han.
      Background: Cisplatin is a widely used anti-tumor agent but its use is frequently limited by nephrotoxicity. Transient receptor potential melastatin 2 (TRPM2) is a non-selective cation channel which is generally viewed as a sensor of oxidative stress, and increasing evidence supports its link with autophagy, a critical process for organelle homeostasis. Methods: Cisplatin-induced cell injury and mitochondrial damage were both assessed in WT and Trpm2-knockout mice and primary cells. RNA sequencing, immunofluorescence staining, immunoblotting and flowcytometry were applied to interpret the mechanism of TRPM2 in cisplatin nephrotoxicity. Results: Knockout of TRPM2 exacerbates renal dysfunction, tubular injury and cell apoptosis in a model of acute kidney injury (AKI) induced by treatment with cisplatin. Cisplatin-caused tubular mitochondrial damage is aggravated in TRPM2-deficient mice and cells and, conversely, alleviated by treatment with Mito-TEMPO, a mitochondrial ROS scavenger. TRPM2 deficiency hinders cisplatin-induced autophagy via blockage of Ca2+ influx and subsequent up-regulation of AKT-mTOR signaling. Consistently, cisplatin-induced tubular mitochondrial damage, cell apoptosis and renal dysfunction in TRPM2-deficient mice are mitigated by treatment with a mTOR inhibitor. Conclusion: Our results suggest that the TRPM2 channel plays a protective role in cisplatin-induced AKI via modulating the Ca2+-AKT-mTOR signaling pathway and autophagy, providing novel insights into the pathogenesis of kidney injury.
    Keywords:  TRPM2; acute kidney injury; autophagy; cisplatin; mitochondria
    DOI:  https://doi.org/10.7150/thno.84655
  44. Br J Pharmacol. 2023 Aug 31.
    Astragalus Polysaccharide Protects Experimental Colitis Through An AhR-Dependent Autophagy Mechanism.
    Yi Ying, Li-Yun Song, Wen-Lin Pang, Si-Qi Zhang, Jing-Ze Yu, Peng-Tao Liang, Tian-Gang Li, Yi Sun, Yin-Ying Wang, Jin-Yuan Yan, Zhong-Shan Yang.
      BACKGROUND AND PURPOSE: Disruption of intestinal barriers plays a vital role in the pathogenesis of colitis. The aryl hydrocarbon receptor (AhR) is a recognition sensor that mediates intestinal immune homeostasis and minimizes intestinal inflammation. Autophagy depends on AhR activation and might constitute a therapeutic target for colitis. Astragalus polysaccharide (APS) exerts pharmacological action in colitis; however, the mechanism has not been elucidated. We aimed to determine whether APS protects colitis through AhR-dependent autophagy.EXPERIMENTAL APPROACH: The symptoms of DSS-induced colitis mice involving intestinal barrier function and inflammatory injury were evaluated after APS administration. Intestinal-specific Becn1 conditional knockout mice (Becn1 cKO) were constructed and compared to WT mice. Autophagy and the therapeutic function of APS were investigated after the deactivation of AhR. The relationship between APS-induced AhR and autophagic Becn1 was investigated using a dual luciferase reporter system and ChIP-qPCR assay. Caco-2 cells investigated inflammatory response and AhR-dependent autophagy.
    KEY RESULTS: APS improved intestinal barrier function in the context of inflammatory injury in the colitis mice. APS triggered autophagic flow, however, knockout of the Becn1 in the gut increased susceptibility to colitis, leading to diminished epithelial barrier function and severe intestinal inflammation, furthermore impairing the protective effects of APS. Mechanistically, APS-triggered autophagy depends on AhR expression. Activated AhR bound to the promoter Becn1 to operate transcription of genes involved in anti-inflammation and intestinal barrier repair, while deactivation of AhR correlated with intestinal inflammation and the therapeutic function of APS.
    CONCLUSION AND IMPLICATIONS: APS protects colitis mice by targeting autophagy, especially that AhR stimulate the repair of damaged intestinal barrier functions.
    Keywords:  Aryl hydrocarbon receptor; Astragalus Polysaccharide; Autophagy; Experimental Colitis
    DOI:  https://doi.org/10.1111/bph.16229
  45. Cell Signal. 2023 Aug 24. pii: S0898-6568(23)00281-4. [Epub ahead of print] 110867
    Autophagy in sepsis-induced acute lung injury: Friend or foe?
    Jiayao Zhao, Qun Liang, Chenfei Fu, Didi Cong, Long Wang, Xiaoxin Xu.
      Sepsis-induced acute lung injury (ALI) is a life-threatening syndrome with high mortality and morbidity, resulting in a heavy burden on family and society. As a key factor that maintains cellular homeostasis, autophagy is regarded as a self-digesting process by which damaged organelles and useless proteins are recycled for cell metabolism, and it thus plays a crucial role during physiological and pathological processes. Recent studies have indicated that autophagy is involved in the pathophysiological process of sepsis-induced ALI, including cell apoptosis, inflammation, and mitochondrial dysfunction, which indicates that regulating autophagy may be beneficial for this disease. However, the role of autophagy in the etiology and treatment of sepsis-induced ALI is not well characterized. This review summarizes the autophagy-related signaling pathways in sepsis-induced ALI, as well as focuses on the dual role of autophagy and its regulation by non-coding RNAs during disease progression, for the development of potential therapeutic strategies in this disease.
    Keywords:  Acute lung injury; Apoptosis; Autophagy; Inflammation; Non-coding RNA; Sepsis
    DOI:  https://doi.org/10.1016/j.cellsig.2023.110867
  46. Exp Mol Med. 2023 Sep 01.
    The stress-responsive protein REDD1 and its pathophysiological functions.
    Ji-Yoon Kim, Young-Guen Kwon, Young-Myeong Kim.
      Regulated in development and DNA damage-response 1 (REDD1) is a stress-induced protein that controls various cellular functions, including metabolism, oxidative stress, autophagy, and cell fate, and contributes to the pathogenesis of metabolic and inflammatory disorders, neurodegeneration, and cancer. REDD1 usually exerts deleterious effects, including tumorigenesis, metabolic inflammation, neurodegeneration, and muscle dystrophy; however, it also exhibits protective functions by regulating multiple intrinsic cell activities through either an mTORC1-dependent or -independent mechanism. REDD1 typically regulates mTORC1 signaling, NF-κB activation, and cellular pro-oxidant or antioxidant activity by interacting with 14-3-3 proteins, IκBα, and thioredoxin-interacting protein or 75 kDa glucose-regulated protein, respectively. The diverse functions of REDD1 depend on cell type, cellular context, interaction partners, and cellular localization (e.g., mitochondria, endomembrane, or cytosol). Therefore, comprehensively understanding the molecular mechanisms and biological roles of REDD1 under pathophysiological conditions is of utmost importance. In this review, based on the published literature, we highlight and discuss the molecular mechanisms underlying the REDD1 expression and its actions, biological functions, and pathophysiological roles.
    DOI:  https://doi.org/10.1038/s12276-023-01056-3
  47. Autophagy. 2023 Sep 01. 1-20
    Rhabdovirus encoded glycoprotein induces and harnesses host antiviral autophagy for maintaining its compatible infection.
    Xiuqin Huang, Junkai Wang, Siping Chen, Siying Liu, Zhanbiao Li, Zhiyi Wang, Biao Chen, Chong Zhang, Yifei Zhang, Jinhui Wu, Xiaorong Yang, Qingjun Xie, Faqiang Li, Hong An, Jilei Huang, Huali Li, Chuanhe Liu, Xiaoxian Wu, Ding Xiang Liu, Xin Yang, Guohui Zhou, Tong Zhang.
      Macroautophagy/autophagy has been recognized as a central antiviral defense mechanism in plant, which involves complex interactions between viral proteins and host factors. Rhabdoviruses are single-stranded RNA viruses, and the infection causes serious harm to public health, livestock, and crop production. However, little is known about the role of autophagy in the defense against rhabdovirus infection by plant. In this work, we showed that Rice stripe mosaic cytorhabdovirus(RSMV) activated autophagy in plants and that autophagy served as an indispensable defense mechanism during RSMV infection. We identified RSMV glycoprotein as an autophagy inducer that interacted with OsSnRK1B and promoted the kinase activity of OsSnRK1B on OsATG6b. RSMV glycoprotein was toxic to rice cells and its targeted degradation by OsATG6b-mediated autophagy was essential to restrict the viral titer in plants. Importantly, SnRK1-glycoprotein and ATG6-glycoprotein interactions were well-conserved between several other rhabdoviruses and plants. Together, our data support a model that SnRK1 senses rhabdovirus glycoprotein for autophagy initiation, while ATG6 mediates targeted degradation of viral glycoprotein. This conserved mechanism ensures compatible infection by limiting the toxicity of viral glycoprotein and restricting the infection of rhabdoviruses.Abbreviations: AMPK: adenosine 5'-monophosphate (AMP)-activated protein kinase; ANOVA: analysis of variance; ATG: autophagy related; AZD: AZD8055; BiFC: bimolecular fluorescence complementation; BYSMV: barley yellow striate mosaic virus; Co-IP: co-immunoprecipitation; ConA: concanamycin A; CTD: C-terminal domain; DEX: dexamethasone; DMSO: dimethyl sulfoxide; G: glycoprotein; GFP: green fluorescent protein; MD: middle domain; MDC: monodansylcadaverine; NTD: N-terminal domain; OE: over expression; Os: Oryza sativa; PBS: phosphate-buffered saline; PtdIns3K: class III phosphatidylinositol-3-kinase; qRT-PCR: quantitative real-time reverse-transcription PCR; RFP: red fluorescent protein; RSMV: rice stripe mosaic virus; RSV: rice stripe virus; SGS3: suppressor of gene silencing 3; SnRK1: sucrose nonfermenting1-related protein kinase1; SYNV: sonchus yellow net virus; TEM: transmission electron microscopy; TM: transmembrane region; TOR: target of rapamycin; TRV: tobacco rattle virus; TYMaV: tomato yellow mottle-associated virus; VSV: vesicular stomatitis virus; WT: wild type; Y2H: yeast two-hybrid; YFP: yellow fluorescent protein.
    Keywords:  ATG6; RSMV; SnRK1; glycoprotein; rhabdovirus
    DOI:  https://doi.org/10.1080/15548627.2023.2252273
  48. Clin Exp Reprod Med. 2023 Sep;50(3): 170-176
    Repopulation of autophagy-deficient stromal cells with autophagy-intact cells after repeated breeding in uterine mesenchyme-specific Atg7 knockout mice.
    Ji-Eun Oh, Sojung Kwon, Hyunji Byun, Haengseok Song, Hyunjung Jade Lim.
      OBJECTIVE: Autophagy is highly active in ovariectomized mice experiencing hormone deprivation, especially in the uterine mesenchyme. Autophagy is responsible for the turnover of vasoactive factors in the uterus, which was demonstrated in anti-Müllerian hormone receptor type 2 receptor (Amhr2)-Cre-driven autophagy-related gene 7 (Atg7) knockout (Amhr-Cre/Atg7f/f mice). In that study, we uncovered a striking difference in the amount of sequestosome 1 (SQSTM1) accumulation between virgin mice and breeder mice with the same genotype. Herein, we aimed to determine whether repeated breeding changed the composition of mesenchymal cell populations in the uterine stroma.METHODS: All female mice used in this study were of the same genotype. Atg7 was deleted by Amhr2 promoter-driven Cre recombinase in the uterine stroma and myometrium, except for a triangular stromal region on the mesometrial side. Amhr-Cre/Atg7f/f female mice were divided into two groups: virgin mice with no mating history and aged between 11 and 12 months, and breeder mice with at least 6-month breeding cycles with multiple pregnancies and aged around 12 months. The uteri were used for Western blotting and immunofluorescence staining.
    RESULTS: SQSTM1 accumulation, representing Atg7 deletion and halted autophagy, was much higher in virgin mice than in breeders. Breeders showed reduced accumulation of several vasoconstrictive factors, which are potential autophagy targets, in the uterus, suggesting that the uterine stroma was repopulated with autophagy-intact cells during repeated pregnancies.
    CONCLUSION: Multiple pregnancies seem to have improved the uterine environment by replacing autophagy-deficient cells with autophagy-intact cells, providing evidence of cell mixing.
    Keywords:  Autophagy; Autophagy-related protein 7; Pregnancy; SQSTM1; Uterus
    DOI:  https://doi.org/10.5653/cerm.2023.05876
  49. Autophagy. 2023 Aug 31. 1-2
    The spatiotemporal control of ER membrane fragmentation during reticulophagy.
    Xinyi Wang, Boran Li, Qiming Sun.
      Reticulophagy is an evolutionarily conserved mechanism essential to maintain the endoplasmic reticulum (ER) homeostasis. A series of studies identified a panel of reticulophagy receptors. However, it remains unclear how these receptors sense upstream signals for spatiotemporal control of reticulophagy and how ER is fragmented into small pieces for sequestration into phagophores. Recently, we and others showed that the oligomerization of RETREG1/FAM134B (reticulophagy regulator 1), an reticulophagy receptor, triggers the scission of ER membrane to facilitate reticulophagy. Furthermore, we demonstrated that upstream signals are transduced by sequential phosphorylation and acetylation of RETREG1, which stimulate its oligomerization, ER fragmentation and reticulophagy. Our work provides further mechanistic insights into how reticulophagy receptor conveys cellular signals to fine-tune of ER homeostasis.Abbreviations: ER, endoplasmic reticulum; MAP1LC3, microtubule-associated protein light chain 3; RETREG1, reticulophagy regulator 1; RHD, reticulon-homology domain.
    Keywords:  RETREG1; acetylation; membrane fragmentation; phosphorylation; reticulophagy
    DOI:  https://doi.org/10.1080/15548627.2023.2252723
  50. Stem Cell Rev Rep. 2023 Aug 29.
    KLF2 Regulates Neural Differentiation of Dental Pulp-derived Stem Cells by Modulating Autophagy and Mitophagy.
    Prateeksha Prateeksha, Prathyusha Naidu, Manjusri Das, Derek Barthels, Hiranmoy Das.
      BACKGROUND: Transplantation of stem cells for treating neurodegenerative disorders is a promising future therapeutic approach. However, the molecular mechanism underlying the neuronal differentiation of dental pulp-derived stem cells (DPSC) remains inadequately explored. The current study aims to define the regulatory role of KLF2 (Kruppel-like factor 2) during the neural differentiation (ND) of DPSC.METHODS: We first investigated the transcriptional and translational expression of KLF2, autophagy, and mitophagy-associated markers during the ND of DPSC by using quantitative RT-PCR and western blot methods. After that, we applied the chemical-mediated loss- and gain-of-function approaches using KLF2 inhibitor, GGPP (geranylgeranyl pyrophosphate), and KLF2 activator, GGTI-298 (geranylgeranyl transferase inhibitor-298) to delineate the role of KLF2 during ND of DPSC. The western blot, qRT-PCR, and immunocytochemistry were performed to determine the molecular changes during ND after KLF2 deficiency and KLF2 sufficiency. We also analyzed the oxygen consumption rate (OCR) and the extracellular acidification rate (ECAR) using the Seahorse XFe24 analyzer.
    RESULTS: Our study demonstrated that the expression level of KLF2, autophagy, and mitophagy-associated markers were significantly elevated during the ND of DPSC. Next, we found that the KLF2 inhibitor, GGPP significantly reduced the ND of DPSC. Inversely, KLF2 overexpression accelerated the molecular phenomenon of DPSC's commitment towards ND, indicating the crucial role of KLF2 in neurogenesis. Moreover, we found that the KLF2 positively regulated autophagy, mitophagy, and the Wnt5a signaling pathway during neurogenesis. Seahorse XFe24 analysis revealed that the ECAR and OCR parameters were significantly increased during ND, and inhibition of KLF2 marginally reversed them towards DPSC's cellular bioenergetics. However, KLF2 overexpression shifted the cellular energy metabolism toward the quiescent stage.
    CONCLUSION: Collectively, our findings provide the first evidence that the KLF2 critically regulates the neurogenesis of DPSC by inducing autophagy and mitophagy.
    Keywords:  Autophagy; DPSC; KLF2; Mitophagy; Neural differentiation
    DOI:  https://doi.org/10.1007/s12015-023-10607-0
  51. Cell Death Dis. 2023 Sep 01. 14(9): 580
    Three-dimensional growth sensitizes breast cancer cells to treatment with ferroptosis-promoting drugs.
    Sandhya Chipurupalli, Peijia Jiang, Xiaoyang Liu, Julia Linhares Santos, Paola Marcato, Kirill V Rosen.
      Drugs causing ferroptosis, iron-mediated cell death, represent promising tools for cancer treatment. While exploring the effect of these drugs on breast cancer (BC), we found that a ferroptosis-inducing drug erastin dramatically inhibits tumorigenicity of human BC cells in mice but when used at a concentration known to effectively kill other cell types only modestly reduces such growth in 2D monolayer culture. BCs grow in vivo as 3D masses, and we found that ferroptosis inducers erastin and sulfasalazine inhibit growth of multiple human BC cell lines in 3D culture significantly stronger than in 2D culture. To understand the mechanism of this differential effect, we found that ferroptosis inducers upregulate mRNAs encoding multiple direct and indirect autophagy stimulators, such as ATG16L2, ATG9A, ATG4D, GABARAP, SQSTM/p62, SEC23A and BAX, in tumor cells growing in 2D but not in 3D culture. Furthermore, these drugs promoted autophagy of tumor cells growing in a 2D but not in a 3D manner. We observed that pharmacological inhibition of autophagy-stimulating protein kinase ULK1 or RNA interference-mediated knockdown of autophagy mediator ATG12 significantly sensitized tumor cells to erastin treatment in 2D culture. We also found that ferroptosis-promoting treatments upregulate heme oxygenase-1 (HO-1) in BC cells. HO-1 increases cellular free iron pool and can potentially promote ferroptosis. Indeed, we observed that HO-1 knockdown by RNA interference reversed the effect of ferroptosis inducers on BC cell 3D growth. Hence, the effect of these drugs on such growth is mediated by HO-1. In summary, autophagy triggered by ferroptosis-promoting drugs reduces their ability to kill BC growing in a 2D manner. This protection mechanism is inhibited in BC cells growing as a 3D mass, and ferroptosis-promoting drugs kill such cells more effectively. Moreover, this death is mediated by HO-1. Thus, ferroptosis induction represents a promising strategy for blocking 3D BC growth.
    DOI:  https://doi.org/10.1038/s41419-023-06106-2
  52. Exp Biol Med (Maywood). 2023 Aug 30. 15353702231191197
    Selective autophagy associated with iron overload aggravates non-alcoholic steatohepatitis via ferroptosis.
    Koki Honma, Sora Kirihara, Hinako Nakayama, Taketo Fukuoka, Toshiaki Ohara, Kazuya Kitamori, Ikumi Sato, Satoshi Hirohata, Moe Fujii, Shusei Yamamoto, Shang Ran, Shogo Watanabe.
      Non-alcoholic steatohepatitis (NASH) is a progressive form of non-alcoholic fatty liver disease (NAFLD) that causes cirrhosis and hepatocellular carcinoma. Iron is an essential trace element in the body; however, excess iron can cause tissue damage and dysfunction. Iron overload is often observed in patients with NASH, and the amount of iron accumulated in the liver positively correlates with the histological severity of NASH. Ferroptosis, a novel form of iron-dependent cell death, is caused by the accumulation of lipid peroxidation and oxidative stress and is related to NASH. In addition, ferroptosis is closely related to autophagy, an intracellular self-degradation process. Although autophagy has many beneficial effects, it may also be harmful to the organism, for example, inducing ferroptosis. It is unclear whether iron overload aggravates NASH via autophagy. The aim of this research is to determine the mechanism by which iron overload induces ferroptosis via autophagy and aggravates NASH. Stroke-prone spontaneously hypertensive rats (SHRSP5/Dmcr) were divided into two groups and fed a high-fat and high-cholesterol (HFC) diet for eight weeks. Iron dextran was administered to the Fe group in addition to the HFC diet. Blood analysis, histological staining, calcineurin activity assay, quantitative reverse transcription polymerase chain reaction (RT-PCR), immunofluorescence staining, and electron microscopy were performed. The results showed that iron overload promoted autophagy via nuclear translocation of transcription factor EB (TFEB) and induced ferritinophagy, which is the autophagic degradation of ferritin. In addition, the HFC diet induced lipophagy, the autophagic degradation of lipid droplets. The Fe group also exhibited promoted ferroptosis and aggravated hepatic inflammation and fibrosis. In conclusion, iron overload accelerates ferritinophagy and lipophagy, aggravating NASH pathology via ferroptosis. These findings indicate the therapeutic potential of inhibiting autophagy and ferroptosis for treating NASH.
    Keywords:  Non-alcoholic steatohepatitis; autophagy; ferritinophagy; ferroptosis; iron overload; lipophagy
    DOI:  https://doi.org/10.1177/15353702231191197
  53. Biochim Biophys Acta Gene Regul Mech. 2023 Aug 30. pii: S1874-9399(23)00076-7. [Epub ahead of print] 194981
    UPS writes a new saga of SAGA.
    Priyanka Barman, Pritam Chakraborty, Rhea Bhaumik, Sukesh R Bhaumik.
      SAGA (Spt-Ada-Gcn5-Acetyltransferase), an evolutionarily conserved transcriptional co-activator among eukaryotes, is a large multi-subunit protein complex with two distinct enzymatic activities, namely HAT (Histone acetyltransferase) and DUB (De-ubiquitinase), and is targeted to the promoter by the gene-specific activator proteins for histone covalent modifications and PIC (Pre-initiation complex) formation in enhancing transcription (or gene activation). Targeting of SAGA to the gene promoter is further facilitated by the 19S RP (Regulatory particle) of the 26S proteasome (that is involved in targeted degradation of protein via ubiquitylation) in a proteolysis-independent manner. Moreover, SAGA is also recently found to be regulated by the 26S proteasome in a proteolysis-dependent manner via the ubiquitylation of its Sgf73/ataxin-7 component that is required for SAGA's integrity and DUB activity (and hence transcription), and is linked to various diseases including neurodegenerative disorders and cancer. Thus, SAGA itself and its targeting to the active gene are regulated by the UPS (Ubiquitin-proteasome system) with implications in diseases.
    Keywords:  SAGA; Sgf73 and ataxin-7; Transcription; UPS
    DOI:  https://doi.org/10.1016/j.bbagrm.2023.194981
  54. Eur J Pharmacol. 2023 Aug 30. pii: S0014-2999(23)00547-2. [Epub ahead of print] 176035
    Targeted inhibition of mTOR by BML-275 induces mitochondrial-mediated apoptosis and autophagy in prostate cancer.
    Wangjian Li, Dongzhang Li, Quan Ma, Yongliang Chen, Zujian Hu, Yongheng Bai, Liping Xie.
      Prostate cancer (PCa) is the most frequently diagnosed cancer among men and the second leading cause of death in Western countries. Clinically, screening drugs and develop developing new therapeutics to treat PCa is of great significance. In this study, BML-275 was demonstrated to exert potent antitumor effects in PCa by antagonizing mTOR activity. In cultured PCa cells, BML-275 treatment reduced the expression levels of c-Myc and survivin, promoted the activation of p53, and thereby induced p21/cyclin D1/CDK4/6-dependent cell cycle G1/S arrest. As a result, BML-275 inhibited cellular proliferation and induced mitochondrial-mediated apoptosis. In addition, BML-275 treatment triggered autophagy. Interestingly, EACC-mediated suppression of autophagy did not affect BML-275-induced proliferation and apoptosis. Nude mouse tumorigenic experiments also confirmed that BML-275 inhibited PCa growth, induced PCa cell apoptosis and autophagy. Mechanistically, the activities of PI3K/AKT and AMPK pathways were downregulated by BML-275 treatment in vitro and in vivo. Importantly, mTOR, a common downstream negative protein of PI3K/AKT and AMPK signaling, was induced to inactivate, which may be associated with the induction of apoptosis and autophagy. The pharmacological activation of mTOR by MHY1485 abolished the induction of apoptosis and autophagy of BML-275. Molecular docking results showed that BML-275 can bind to the FKRP12-rapamycin binding site on mTOR protein, and thereby may have the same inhibitory activity on mTOR as rapamycin. Thus, these findings indicated that BML-275 induces mitochondrial-mediated apoptosis and autophagy in PCa by targeting mTOR inhibition. BML-275 may be a potential candidate for the treatment of PCa.
    Keywords:  AMPK; BML-275; PI3K/AKT; Prostate cancer (PCa); mTOR
    DOI:  https://doi.org/10.1016/j.ejphar.2023.176035
  55. Chem Sci. 2023 Aug 30. 14(34): 9136-9144
    Fluorescence polarisation activity-based protein profiling for the identification of deoxynojirimycin-type inhibitors selective for lysosomal retaining alpha- and beta-glucosidases.
    Daniël van der Gracht, Rhianna J Rowland, Véronique Roig-Zamboni, Maria J Ferraz, Max Louwerse, Paul P Geurink, Johannes M F G Aerts, Gerlind Sulzenbacher, Gideon J Davies, Herman S Overkleeft, Marta Artola.
      Lysosomal exoglycosidases are responsible for processing endocytosed glycans from the non-reducing end to produce the corresponding monosaccharides. Genetic mutations in a particular lysosomal glycosidase may result in accumulation of its particular substrate, which may cause diverse lysosomal storage disorders. The identification of effective therapeutic modalities to treat these diseases is a major yet poorly realised objective in biomedicine. One common strategy comprises the identification of effective and selective competitive inhibitors that may serve to stabilize the proper folding of the mutated enzyme, either during maturation and trafficking to, or residence in, endo-lysosomal compartments. The discovery of such inhibitors is greatly aided by effective screening assays, the development of which is the focus of the here-presented work. We developed and applied fluorescent activity-based probes reporting on either human GH30 lysosomal glucosylceramidase (GBA1, a retaining β-glucosidase) or GH31 lysosomal retaining α-glucosidase (GAA). FluoPol-ABPP screening of our in-house 358-member iminosugar library yielded compound classes selective for either of these enzymes. In particular, we identified a class of N-alkyldeoxynojirimycins that inhibit GAA, but not GBA1, and that may form the starting point for the development of pharmacological chaperone therapeutics for the lysosomal glycogen storage disease that results from genetic deficiency in GAA: Pompe disease.
    DOI:  https://doi.org/10.1039/d3sc01021j
  56. J Biochem Mol Toxicol. 2023 Aug 31. e23523
    Endoplasmic reticulum stress-mediated autophagy alleviates lipopolysaccharide-induced nucleus pulposus cell pyroptosis by inhibiting CHOP signaling in vitro.
    Lu Chen, Lei Zhu, Hang Shi, Zhi-Yang Xie, Zan-Li Jiang, Zheng-Yuan Xu, Zi-Jian Zhang, Xiao-Tao Wu.
      Pyroptosis, a newly discovered pro-inflammatory programmed necrosis of cells, serves as an initiating and promoting event that leads to intervertebral disc (IVD) degeneration (IDD). Endoplasmic reticulum stress (ERS) and autophagy are vital regulatory mechanisms of cellular homeostasis, which is also closely related to IDD. However, the role and relationship of ERS and autophagy in the pyroptosis of nucleus pulposus cell (NPC) are not well understood. In this research, we aimed to elucidate the role and mechanism of ERS-C/EBP homologous protein (CHOP) in lipopolysaccharide (LPS)-induced cell pyroptosis and determine its interaction with autophagy. ERS and autophagy inducers or inhibitors were used or not in the preconditioning of rat NPCs. Cell viability, pyroptosis-related protein expression, caspase-1 activity assay, and enzyme-linked immunosorbent assay were performed to observe rat NPC pyroptosis after the treatment of LPS. Activation of the ERS pathway and autophagy were assessed by quantitative real-time PCR, western blot analyses, and immunofluorescence staining assay to classify the molecular mechanisms. Our results showed that LPS stimulation induced NPC pyroptosis with concomitant activation of the ERS-CHOP pathway and initiated autophagy. Activation of the ERS-CHOP pathway exacerbated rat NPC pyroptosis, whereas autophagy inhibited cell pyroptosis. LPS-induced cell pyroptosis and CHOP upregulation were negatively regulated by autophagy. LPS-induced autophagy was depressed by the ERS inhibitor but aggravated by the ERS inducer. Taken together, our findings suggested that LPS induced NPC pyroptosis by activating ERS-CHOP signaling and ERS mediated LPS-induced autophagy, which in turn alleviated NPC pyroptosis by inhibiting CHOP signaling.
    Keywords:  autophagy; endoplasmic reticulum stress; intervertebral disc degeneration; nucleus pulposus cell; pyroptosis
    DOI:  https://doi.org/10.1002/jbt.23523
  57. Cytoskeleton (Hoboken). 2023 Aug 28.
    Dysregulation of mTOR by tau in Alzheimer's disease.
    George S Bloom, Andrés Norambuena.
      Tau was discovered in the mid 1970's as a microtubule-associated protein that stimulates tubulin polymerization, and subsequently was shown to be expressed primarily in neurons, where it is most concentrated in axons. Interest in tau rose by the late 1980's, when it was shown to be the principal subunit of the neurofibrillary tangles (NFTs) that accumulate in Alzheimer's disease (AD) brain, and achieved new heights by the late 1990's, when numerous tau mutations were found to be highly penetrant for AD-related disorders that also are associated with NFTs and came to be known as non-Alzheimer's tauopathies. The role of tau in neurodegeneration is far more complex than whatever effects on neurons may be caused by NFTs, however, and here we review our work on dysregulation of mTOR by tau in AD. mTOR is a protein kinase and master regulator of myriad aspects of cellular behavior. We have defined a complex signaling network whereby aberrant tau phosphorylation provoked by amyloid-β oligomers (AβOs), the building blocks of the amyloid plaques that form in AD brain, cause post-mitotic neurons to re-enter the cell cycle, but to die eventually instead of dividing, which may account for most neuron death in AD. Remarkably, we found that this same neuronal signaling network also poisons a fundamental cell biological process that we discovered, nutrient-induced mitochondrial activation, or NiMA. Tau-dependent cell cycle re-entry and NiMA inhibition occur in cultured neurons within a few hours of exposure to AβOs, and thus may represent seminal processes in AD pathogenesis.
    Keywords:  Alzheimer's disease; mTOR; tau; tauopathies
    DOI:  https://doi.org/10.1002/cm.21782
  58. Biochem Biophys Res Commun. 2023 Aug 24. pii: S0006-291X(23)00994-4. [Epub ahead of print]678 186-192
    Hsa_circ_0000585 promotes chemoresistance to cis-platin in epithelial cells of ovarian cancer by modulating autophagy.
    Pei Du, Xueyuan Xu, Ying Wang.
      BACKGROUND: Chemoresistance, i.e., resistance to cisplatin (DDP), has been a major obstacle to ovarian cancer treatment. It has been found that circular RNAs (circRNAs) play vital roles in the tumorigenesis various cancers by regulating autophagy, while few studies focusing on cisplatin-resistance ovarian cancer (CROC).METHODS: The expressions of the circRNAs were detected by qRT-PCR. Short hairpin RNA targeting circRNA was used to explore the biological functions of the circRNA. Cell viability, autophagic flux, immunofluorescence, and xenograft tumors experiments were performed to further illustrate the underlying mechanisms.
    RESULTS: Hsa_circ_0000585 was increased in cisplatin-resistant SKOV3/DDP cells. Stably knocking down hsa_circRNA_0000585 expression in SKOV3/DDP cells was established by RNA interference. We found that downregulation of hsa_circ_0000585 significantly enhanced the sensitivity of DDP/SkOV3 cells to DDP. In vivo study, hsa_circRNA_0000585 knockdown significantly decreased tumor volume in nude mice. Under the measurements of western blot and cellular immunofluorescence, hsa_circ_0000585 knockdown significantly inhibited the expression of Beclin1 and P62, indicating the autophagic flux was inhibited. Administrations with autophagic inhibitor "Chloroquine (CQ)" and autophagy activator "QX77" further confirmed that hsa_circ_0000585 knockdown resulted in autophagy inhibition.
    CONCLUSIONS: Overall, this study provided a new insight into the role of circRNAs in the mechanism of DDP-resistance in ovarian cancer. Hsa_circRNA_0000585 may be promising therapeutic targets for the enhancement of the sensitivity of ovarian cancer cells to cisplatin-mediated chemotherapy.
    Keywords:  Autophagy; Cisplatin; Hsa_circRNA_0000585; Mechanism; Ovarian cancer
    DOI:  https://doi.org/10.1016/j.bbrc.2023.08.048
  59. Cell Death Dis. 2023 08 29. 14(8): 571
    Plk1 promotes renal tubulointerstitial fibrosis by targeting autophagy/lysosome axis.
    Yang Du, Yaqiong Shang, Yun Qian, Yan Guo, Shuang Chen, Xiuli Lin, Weidong Cao, Xiaomei Tang, Anning Zhou, Songming Huang, Aihua Zhang, Zhanjun Jia, Yue Zhang.
      The prevalence of chronic kidney disease (CKD) has been increasing over the past decades. However, no effective therapies are available for delaying or curing CKD. Progressive fibrosis is the major pathological feature of CKD, which leads to end-stage renal disease (ESRD). The present study showed that Polo-like kinase 1 (Plk1) was upregulated in the kidneys of CKD patients and mice subjected to unilateral ureteral obstruction (UUO) with location in proximal tubules and tubulointerstitial fibroblasts. Pharmacological inhibition, genetic silencing or knockout of Plk1 attenuated obstructive nephropathy due to suppressed fibroblast activation mediated by reduced autophagic flux. We found Plk1 plays a critical role in maintaining intralysosomal pH by regulating ATP6V1A phosphorylation, and inhibition of Plk1 impaired lysosomal function leading to blockade of autophagic flux. In addition, Plk1 also prevented partial epithelial-mesenchymal transition (pEMT) of tubular epithelial cells via autophagy pathway. In conclusion, this study demonstrated that Plk1 plays a pathogenic role in renal tubulointerstitial fibrosis by regulating autophagy/lysosome axis. Thus, targeting Plk1 could be a promising strategy for CKD treatment.
    DOI:  https://doi.org/10.1038/s41419-023-06093-4
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