bims-auttor Biomed News
on Autophagy and mTOR
Issue of 2024–06–16
sixty-nine papers selected by
Viktor Korolchuk, Newcastle University
  1. mTOR inhibition in Q175 Huntington's disease model mice facilitates neuronal autophagy and mutant huntingtin clearance.
  2. Dysregulation of pancreatic β-cell autophagy and the risk of type 2 diabetes.
  3. Pathobiology of the autophagy-lysosomal pathway in the Huntington's disease brain.
  4. Downregulation of O-GlcNAc transferase activity impairs basal autophagy and late endosome positioning under nutrient-rich conditions in human colon cells.
  5. ARHGAP26/GRAF1 orchestrates actin remodeling and membrane dynamics to drive mitochondrial clearance and promote fuel flexibility.
  6. The interplay between mitophagy and mitochondrial ROS in acute lung injury.
  7. The roles of secretory autophagy in mitochondria release via extracellular vesicles: waste disposal and food delivery?
  8. Inhibition of Insulin Secretion Induces Golgi Morphological Changes.
  9. Suppression of autophagy induces senescence in the heart.
  10. Tau fibrils evade autophagy by excessive p62 coating and TAX1BP1 exclusion.
  11. Glucose deprivation triggers DCAF1-mediated inactivation of Rheb-mTORC1 and promotes cancer cell survival.
  12. Tetramethylpyrazine nitrone delays the aging process of C. elegans by improving mitochondrial function through the AMPK/mTORC1 signaling pathway.
  13. The different roles of V-ATPase a subunits in phagocytosis/endocytosis and autophagy.
  14. Targeting mTOR signaling pathways in multiple myeloma: biology and implication for therapy.
  15. Signal-sustained imaging of mitophagy with an Enzyme-Activatable Metabolic Lipid-Labeling Probe.
  16. Dengue virus exploits autophagy vesicles and secretory pathways to promote transmission by human dendritic cells.
  17. JEV infection leads to dysfunction of lysosome by downregulating the expression of LAMP1 and LAMP2.
  18. The Ubiquitin Ligase RBX2/SAG Regulates Mitochondrial Ubiquitination and Mitophagy.
  19. MTFP1 controls mitochondrial fusion to regulate inner membrane quality control and maintain mtDNA levels.
  20. Human tNeurons reveal aging-linked proteostasis deficits driving Alzheimer's phenotypes.
  21. Polydatin: a potential NAFLD therapeutic drug that regulates mitochondrial autophagy through SIRT3-FOXO3-BNIP3 and PINK1-PRKN mechanisms - a network pharmacology and experimental investigation.
  22. Altered Autophagic Flux in GNE mutant cells of Indian Origin: potential drug target for GNE Myopathy.
  23. Diverse Functions of Parkin in Midbrain Dopaminergic Neurons.
  24. The Role and Mechanism of Ambra1-Mediated Mitophagy in TDCPP-Exposed Mouse Hippocampal Neurons.
  25. Lysosomal exocytosis: From cell protection to protumoral functions.
  26. Advances in SIRT3 involvement in regulating autophagy-related mechanisms.
  27. C16ORF70/Mytho promotes healthy ageing in C. elegans and prevents cellular senescence in mammals.
  28. Mutations in CLCN6 as a Novel Genetic Cause of Neuronal Ceroid Lipofuscinosis.
  29. Partitioning into ER membrane microdomains impacts autophagic protein turnover during cellular aging.
  30. Activation of BK channels prevents diabetes-induced osteopenia by regulating mitochondrial Ca2+ and SLC25A5/ANT2-PINK1-PRKN-mediated mitophagy.
  31. REST-dependent downregulation of von Hippel-Lindau tumor suppressor promotes autophagy in SHH-medulloblastoma.
  32. The autophagy protein RUBCNL/PACER represses RIPK1 kinase-dependent apoptosis and necroptosis.
  33. Mitochondrial quality control dysfunction in osteoarthritis: Mechanisms, therapeutic strategies & future prospects.
  34. Alpha-Hederin induces incomplete autophagic injury in non-small cell lung cancer by interfering with the lysosomal acidification.
  35. Mitochondrial alterations in fibroblasts from sporadic Alzheimer's disease (AD) patients correlate with AD-related clinical hallmarks.
  36. Cleavage of Hsp70.1 causes lysosomal cell death under stress conditions.
  37. Effects of metformin on cancers in experimental and clinical studies: Focusing on autophagy and AMPK/mTOR signaling pathways.
  38. Rapamycin promotes the intestinal barrier repair in ulcerative colitis via the mTOR/PBLD/AMOT signaling pathway.
  39. LDHA contributes to nicotine induced cardiac fibrosis through autophagy flux impairment.
  40. Signaling proteins in HSC fate determination are unequally segregated during asymmetric cell division.
  41. Inhibition of CIRBP represses the proliferation and migration of vascular smooth muscle cells via inhibiting Rheb/mTORC1 axis.
  42. Pharmacological mTOR inhibitors in ameliorating Alzheimer's disease: current review and perspectives.
  43. Discovery of autophagy-tethering compounds as potent NLRP3 degraders for IBD Immunotherapy.
  44. Atlastin-1 regulates endosomal tubulation and lysosomal proteolysis in human cortical neurons.
  45. Mitoxantrone ameliorates ineffective erythropoiesis in a β-thalassemia intermedia mouse model.
  46. Activation of the cell wall integrity pathway negatively regulates TORC2-Ypk1/2 signaling through blocking eisosome disassembly in Saccharomyces cerevisiae.
  47. The necroptosis cell death pathway drives neurodegeneration in Alzheimer's disease.
  48. Improving STING agonist-based cancer therapy by inhibiting the autophagy-related protein VPS34.
  49. ACE2 mediates tryptophan alleviation on diarrhea by repairing intestine barrier involved mTOR pathway.
  50. Effect of alternating nicotinamide phosphoribosyltransferase expression levels on mitophagy in Alzheimer's disease mouse models.
  51. SS-31 treatment ameliorates cardiac mitochondrial morphology and defective mitophagy in a murine model of Barth syndrome.
  52. Pyruvate kinase M2 sustains cardiac mitochondrial quality surveillance in septic cardiomyopathy by regulating prohibitin 2 abundance via S91 phosphorylation.
  53. Myricanol prevents aging-related sarcopenia by rescuing mitochondrial dysfunction via targeting peroxiredoxin 5.
  54. Transforming growth factor-β1 protects mechanically injured cortical murine neurons by reducing trauma-induced autophagy and apoptosis.
  55. Bacterial esterases reverse lipopolysaccharide ubiquitylation to block host immunity.
  56. Regulatory Mechanisms of Aging Through the Nutritional and Metabolic Control of Amino Acid Signaling in Model Organisms.
  57. Human gastric cancer progression and stabilization of ATG2B through RNF5 binding facilitated by autophagy-associated CircDHX8.
  58. FICD deficiency protects mice from hypertrophy-induced heart failure via BiP-mediated activation of the UPR ER and ER-phagy.
  59. Acteoside delays the fibrosis process of diabetic nephropathy by anti-oxidation and regulating the autophagy-lysosome pathway.
  60. 20-Deoxyingenol Activates Mitophagy Through TFEB and Promotes Functional Recovery After Spinal Cord Injury.
  61. Immunological synapse formation between T regulatory cells and cancer-associated fibroblasts promotes tumour development.
  62. Pink1/Parkin deficiency alters circulating lymphocyte populations and increases platelet-T cell aggregates in rats.
  63. Fibroblast growth factor 21 alleviates idiopathic pulmonary fibrosis by inhibiting PI3K-AKT-mTOR signaling and stimulating autophagy.
  64. Autophagy unveiled: New horizons in health and disease.
  65. Loss of the lysosomal protein CLN3 modifies the lipid content of the nuclear envelope leading to DNA damage and activation of YAP1 pro-apoptotic signaling.
  66. Tricetin protects against liver fibrosis through promoting autophagy and Nrf2 signaling in hepatic stellate cells.
  67. Reproductive regulation of the mitochondrial stress response in Caenorhabditis elegans.
  68. Unconventional mechanism of action and resistance to rapalogs in renal cancer.
  69. Protocol for qualitative analysis of lysosome immunoprecipitation from patient-derived glioblastoma stem-like cells.
  1. bioRxiv. 2024 May 30. pii: 2024.05.29.596471. [Epub ahead of print]
    mTOR inhibition in Q175 Huntington's disease model mice facilitates neuronal autophagy and mutant huntingtin clearance.
    Philip Stavrides, Chris N Goulbourne, James Peddy, Chunfeng Huo, Mala Rao, Vinod Khetarpal, Deanna M Marchionini, Ralph A Nixon, Dun-Sheng Yang.
      Huntington's disease (HD) is caused by expansion of the polyglutamine stretch in huntingtin protein (HTT) resulting in hallmark aggresomes/inclusion bodies (IBs) composed of mutant huntingtin protein (mHTT) and its fragments. Stimulating autophagy to enhance mHTT clearance is considered a potential therapeutic strategy for HD. Our recent evaluation of the autophagic-lysosomal pathway (ALP) in human HD brain reveals upregulated lysosomal biogenesis and relatively normal autophagy flux in early Vonsattel grade brains, but impaired autolysosome clearance in late grade brains, suggesting that autophagy stimulation could have therapeutic benefits as an earlier clinical intervention. Here, we tested this hypothesis by crossing the Q175 HD knock-in model with our autophagy reporter mouse TRGL ( T hy-1- R FP- G FP- L C3) to investigate in vivo neuronal ALP dynamics. In the Q175 and/or TRGL/Q175 mice, mHTT was detected in autophagic vacuoles and also exhibited high level colocalization with autophagy receptors p62/SQSTM1 and ubiquitin in the IBs. Compared to the robust lysosomal pathology in late-stage human HD striatum, ALP alterations in Q175 models are also late-onset but milder that included a lowered phospho-p70S6K level, lysosome depletion and autolysosome elevation including more poorly acidified autolysosomes and larger-sized lipofuscin granules, reflecting impaired autophagic flux. Administration of a mTOR inhibitor to 6-mo-old TRGL/Q175 normalized lysosome number, ameliorated aggresome pathology while reducing mHTT-, p62- and ubiquitin-immunoreactivities, suggesting beneficial potential of autophagy modulation at early stages of disease progression.
    DOI:  https://doi.org/10.1101/2024.05.29.596471
  2. Autophagy. 2024 Jun 14.
    Dysregulation of pancreatic β-cell autophagy and the risk of type 2 diabetes.
    Hayder M Al-Kuraishy, Majid S Jabir, Ali I Al-Gareeb, Daniel J Klionsky, Ali K Albuhadily.
      Autophagy is an essential degradation process that removes abnormal cellular components, maintains homeostasis within cells, and provides nutrition during starvation. Activated autophagy enhances cell survival during stressful conditions, although overactivation of autophagy triggers induction of autophagic cell death. Therefore, early-onset autophagy promotes cell survival whereas late-onset autophagy provokes programmed cell death which prevents disease progression in different diseases. Moreover, autophagy regulates pancreatic β cell functions by different mechanisms, although the precise role of autophagy in type 2 diabetes (T2D) is not completely understood. Consequently, this mini-review discusses the protective and harmful roles of autophagy in the pancreatic β-cell and in the pathophysiology of T2D.
    Keywords:  Autophagy; pancreatic β cell; type 2 diabetes
    DOI:  https://doi.org/10.1080/15548627.2024.2367356
  3. bioRxiv. 2024 May 30. pii: 2024.05.29.596470. [Epub ahead of print]
    Pathobiology of the autophagy-lysosomal pathway in the Huntington's disease brain.
    Martin J Berg, Veeranna, Corrinne M Rosa, Asok Kumar, Panaiyur S Mohan, Philip Stavrides, Deanna M Marchionini, Dun-Sheng Yang, Ralph A Nixon.
      Accumulated levels of mutant huntingtin protein (mHTT) and its fragments are considered contributors to the pathogenesis of Huntington's disease (HD). Although lowering mHTT by stimulating autophagy has been considered a possible therapeutic strategy, the role and competence of autophagy-lysosomal pathway (ALP) during HD progression in the human disease remains largely unknown. Here, we used multiplex confocal and ultrastructural immunocytochemical analyses of ALP functional markers in relation to mHTT aggresome pathology in striatum and the less affected cortex of HD brains staged from HD2 to HD4 by Vonsattel neuropathological criteria compared to controls. Immunolabeling revealed the localization of HTT/mHTT in ALP vesicular compartments labeled by autophagy-related adaptor proteins p62/SQSTM1 and ubiquitin, and cathepsin D (CTSD) as well as HTT-positive inclusions. Although comparatively normal at HD2, neurons at later HD stages exhibited progressive enlargement and clustering of CTSD-immunoreactive autolysosomes/lysosomes and, ultrastructurally, autophagic vacuole/lipofuscin granules accumulated progressively, more prominently in striatum than cortex. These changes were accompanied by rises in levels of HTT/mHTT and p62/SQSTM1, particularly their fragments, in striatum but not in the cortex, and by increases of LAMP1 and LAMP2 RNA and LAMP1 protein. Importantly, no blockage in autophagosome formation and autophagosome-lysosome fusion was detected, thus pinpointing autophagy substrate clearance deficits as a basis for autophagic flux declines. The findings collectively suggest that upregulated lysosomal biogenesis and preserved proteolysis maintain autophagic clearance in early-stage HD, but failure at advanced stages contributes to progressive HTT build-up and potential neurotoxicity. These findings support the prospect that ALP stimulation applied at early disease stages, when clearance machinery is fully competent, may have therapeutic benefits in HD patients.
    DOI:  https://doi.org/10.1101/2024.05.29.596470
  4. Biochem Biophys Res Commun. 2024 Jun 03. pii: S0006-291X(24)00734-4. [Epub ahead of print]724 150198
    Downregulation of O-GlcNAc transferase activity impairs basal autophagy and late endosome positioning under nutrient-rich conditions in human colon cells.
    Awatef Ben Ahmed, Jodie Scache, Marlène Mortuaire, Tony Lefebvre, Anne-Sophie Vercoutter-Edouart.
      Autophagy is a critical catabolic pathway that enables cells to survive and adapt to stressful conditions, especially nutrient deprivation. The fusion of autophagic vacuoles with lysosomes is the final step of autophagy, which degrades the engulfed contents into metabolic precursors for re-use by the cell. O-GlcNAc transferase (OGT) plays a crucial role in regulating autophagy flux in response to nutrient stress, particularly by targeting key proteins involved in autophagosome-lysosome fusion. However, the role of OGT in basal autophagy, which occurs at a low and constitutive levels under growth conditions, remains poorly understood. Silencing or inhibition of OGT was used to compare the effect of OGT downregulation on autophagy flux in the non-cancerous CCD841CoN and cancerous HCT116 human colon cell lines under nutrient-rich conditions. We provide evidence that the reduction of OGT activity impairs the maturation of autophagosomes, thereby blocking the completion of basal autophagy in both cell lines. Additionally, OGT inhibition results in the accumulation of lysosomes and enlarged late endosomes in the perinuclear region, as demonstrated by confocal imaging. This is associated with a defect in the localization of the small GTPase Rab7 to these organelles. The regulation of transport and fusion events between the endosomal and lysosomal compartments is crucial for maintaining the autophagic flux. These findings suggest an interplay between OGT and the homeostasis of the endolysosomal network in human cells.
    Keywords:  Basal autophagy; Colon cells; Late endosome; Lysosome positioning; O-GlcNAc transferase; Rab7
    DOI:  https://doi.org/10.1016/j.bbrc.2024.150198
  5. Autophagy. 2024 Jun 10. 1-3
    ARHGAP26/GRAF1 orchestrates actin remodeling and membrane dynamics to drive mitochondrial clearance and promote fuel flexibility.
    Qiang Zhu, Joan M Taylor.
      The serine/threonine kinase, PINK1, and the E3 ubiquitin ligase, PRKN/Parkin facilitate LC3-dependent autophagosomal encasement and lysosomal clearance of dysfunctional mitochondria, and defects in this pathway contribute to the pathogenesis of numerous cardiometabolic and neurological diseases. Although dynamic actin remodeling has recently been shown to play an important role in governing spatiotemporal control of mitophagy, the mechanisms remain unclear. We recently found that the RhoGAP, ARHGAP26/GRAF1 is a PRKN-binding protein that is rapidly recruited to damaged mitochondria where upon phosphorylation by PINK1 it serves to coordinate phagophore capture by regulating mitochondrial-associated actin remodeling and by facilitating PRKN-LC3 interactions. Because ARHGAP26 phosphorylation on PINK1-dependent sites is dysregulated in human heart failure and ARHGAP26 depletion in mouse hearts blunts mitochondrial clearance and attenuates compensatory metabolic adaptations to stress, this enzyme may be a tractable target to treat the many diseases associated with mitochondrial dysfunction.
    Keywords:  Actin dynamics; GRAF1; PINK1; Parkin; mitophagy
    DOI:  https://doi.org/10.1080/15548627.2024.2361576
  6. Mitochondrion. 2024 Jun 12. pii: S1567-7249(24)00078-3. [Epub ahead of print] 101920
    The interplay between mitophagy and mitochondrial ROS in acute lung injury.
    Yizhi Zhong, Siwei Xia, Gaojian Wang, Qinxue Liu, Fengjie Ma, Yijin Yu, Yaping Zhang, Lu Qian, Li Hu, Junran Xie.
      Mitochondria orchestrate the production of new mitochondria and the removal of damaged ones to dynamically maintain mitochondrial homeostasis through constant biogenesis and clearance mechanisms. Mitochondrial quality control particularly relies on mitophagy, defined as selective autophagy with mitochondria-targeting specificity. Most ROS are derived from mitochondria, and the physiological concentration of mitochondrial ROS (mtROS) is no longer considered a useless by-product, as it has been proven to participate in immune and autophagy pathway regulation. However, excessive mtROS appears to be a pathogenic factor in several diseases, including acute lung injury (ALI). The interplay between mitophagy and mtROS is complex and closely related to ALI. Here, we review the pathways of mitophagy, the intricate relationship between mitophagy and mtROS, the role of mtROS in the pathogenesis of ALI, and their effects and related progression in ALI induced by different conditions.
    Keywords:  Acute lung injury; Mechanism; Mitochondrial reactive oxygen species; Mitophagy; Oxidative stress
    DOI:  https://doi.org/10.1016/j.mito.2024.101920
  7. Front Cell Dev Biol. 2024 ;12 1392810
    The roles of secretory autophagy in mitochondria release via extracellular vesicles: waste disposal and food delivery?
    Yuhan Gong, Yucheng Zhou, Linhui Feng, Yuting Zhao.
      
    Keywords:  autophagosome formation; extracellular vesicles; membrane fusion; mitochondria; mitophagosome; mitophagy; secretory autophagy
    DOI:  https://doi.org/10.3389/fcell.2024.1392810
  8. Juntendo Iji Zasshi. 2023 ;69(1): 42-49
    Inhibition of Insulin Secretion Induces Golgi Morphological Changes.
    Tatsuya Iwamoto, Shigeomi Shimizu, Hajime Tajima-Sakurai, Hirofumi Yamaguchi, Yuya Nishida, Satoko Arakawa, Hirotaka Watada.
       Objectives: The role of autophagy in pancreatic β cells has been reported, but the relationship between autophagy and insulin metabolism is complex and is not fully understood yet.
    Design: We here analyze the relationship between autophagy and insulin metabolism from a morphological aspect.
    Methods: We observe the morphological changes of β cell-specific Atg7-deficient mice and Atg5-deficient MIN6 cells with electron microscopy.
    Results: We find that Atg7-deficient β cells exhibit a marked expansion of the endoplasmic reticulum (ER). We also find that the inhibitory state of insulin secretion causes morphological changes in the Golgi, including ministacking and swelling. The same morphological alterations are observed when insulin secretion is suppressed in Atg5-deficient MIN6 cells.
    Conclusions: The defect of autophagy induces ER expansion, and inhibition of insulin secretion induces Golgi swelling, probably via ER stress and Golgi stress, respectively.
    Keywords:  ER; Golgi; autophagy; diazoxide; pancreatic β cells
    DOI:  https://doi.org/10.14789/jmj.JMJ22-0040-OA
  9. bioRxiv. 2024 May 30. pii: 2024.05.26.595978. [Epub ahead of print]
    Suppression of autophagy induces senescence in the heart.
    Peiyong Zhai, Eun-Ah Sung, Yuka Shiheido-Watanabe, Koichiro Takayama, Yimin Tian, Junichi Sadoshima.
      Aging is a critical risk factor for heart disease, including ischemic heart disease and heart failure. Cellular senescence, characterized by DNA damage, resistance to apoptosis and the senescence-associated secretory phenotype (SASP), occurs in many cell types, including cardiomyocytes. Senescence precipitates the aging process in surrounding cells and the organ through paracrine mechanisms. Generalized autophagy, which degrades cytosolic materials in a non-selective manner, is decreased during aging in the heart. This decrease causes deterioration of cellular quality control mechanisms, facilitates aging and negatively affects lifespan in animals, including mice. Although suppression of generalized autophagy could promote senescence, it remains unclear whether the suppression of autophagy directly stimulates senescence in cardiomyocytes, which, in turn, promotes myocardial dysfunction in the heart. We addressed this question using mouse models with a loss of autophagy function. Suppression of general autophagy in cardiac-specific Atg7 knockout ( Atg7 cKO) mice caused accumulation of senescent cardiomyocytes. Induction of senescence via downregulation of Atg7 was also observed in chimeric Atg7 cardiac-specific KO mice and cultured cardiomyocytes in vitro , suggesting that the effect of autophagy suppression upon induction of senescence is cell autonomous. ABT-263, a senolytic agent, reduced the number of senescent myocytes and improved cardiac function in Atg7 cKO mice. Suppression of autophagy and induction of senescence were also observed in doxorubicin-treated hearts, where activation of autophagy alleviated senescence in cardiomyocytes and cardiac dysfunction. These results suggest that suppression of general autophagy directly induces senescence in cardiomyocytes, which in turn promotes cardiac dysfunction.
    DOI:  https://doi.org/10.1101/2024.05.26.595978
  10. Sci Adv. 2024 Jun 14. 10(24): eadm8449
    Tau fibrils evade autophagy by excessive p62 coating and TAX1BP1 exclusion.
    Luca Ferrari, Bernd Bauer, Yue Qiu, Martina Schuschnig, Sigrid Klotz, Dorothea Anrather, Thomas Juretschke, Petra Beli, Ellen Gelpi, Sascha Martens.
      The accumulation of protein aggregates is a hallmark of many diseases, including Alzheimer's disease. As a major pillar of the proteostasis network, autophagy mediates the degradation of protein aggregates. The autophagy cargo receptor p62 recognizes ubiquitin on proteins and cooperates with TAX1BP1 to recruit the autophagy machinery. Paradoxically, protein aggregates are not degraded in various diseases despite p62 association. Here, we reconstituted the recognition by the autophagy receptors of physiological and pathological Tau forms. Monomeric Tau recruits p62 and TAX1BP1 via the sequential actions of the chaperone and ubiquitylation machineries. In contrast, Tau fibrils from Alzheimer's disease brains are recognized by p62 but fail to recruit TAX1BP1. This failure is due to the masking of fibrils ubiquitin moieties by p62. Tau fibrils are resistant to deubiquitylation, and, thus, this nonproductive interaction of p62 with the fibrils is irreversible. Our results shed light on the mechanism underlying autophagy evasion by protein aggregates and their consequent accumulation in disease.
    DOI:  https://doi.org/10.1126/sciadv.adm8449
  11. Cell Death Dis. 2024 Jun 11. 15(6): 409
    Glucose deprivation triggers DCAF1-mediated inactivation of Rheb-mTORC1 and promotes cancer cell survival.
    Miaomiao Li, Wenjing Huang, Yuan Zhang, Yue Du, Shan Zhao, Longhao Wang, Yaxin Sun, Beibei Sha, Jie Yan, Yangcheng Ma, Jinlu Tang, Jianxiang Shi, Pei Li, Lijun Jia, Tao Hu, Ping Chen.
      Low glucose is a common microenvironment for rapidly growing solid tumors, which has developed multiple approaches to survive under glucose deprivation. However, the specific regulatory mechanism remains largely elusive. In this study, we demonstrate that glucose deprivation, while not amino acid or serum starvation, transactivates the expression of DCAF1. This enhances the K48-linked polyubiquitination and proteasome-dependent degradation of Rheb, inhibits mTORC1 activity, induces autophagy, and facilitates cancer cell survival under glucose deprivation conditions. This study identified DCAF1 as a new cellular glucose sensor and uncovered new insights into mechanism of DCAF1-mediated inactivation of Rheb-mTORC1 pathway for promoting cancer cell survival in response to glucose deprivation.
    DOI:  https://doi.org/10.1038/s41419-024-06808-1
  12. Biochem Biophys Res Commun. 2024 Jun 03. pii: S0006-291X(24)00756-3. [Epub ahead of print]723 150220
    Tetramethylpyrazine nitrone delays the aging process of C. elegans by improving mitochondrial function through the AMPK/mTORC1 signaling pathway.
    Ting Zhang, Mei Jing, Lili Fei, Zaijun Zhang, Peng Yi, Yewei Sun, Yuqiang Wang.
      Aging is characterized as the process of functional decline in an organism from adulthood, often marked by a progressive loss of cellular function and systemic deterioration of multiple tissues. Among the numerous molecular, cellular, and systemic hallmarks associated with aging, mitochondrial dysfunction is considered one of the pivotal factors that initiates the aging process. During aging, mitochondria undergo varying degrees of damage, resulting in impaired energy production and disruption of the homeostatic regulation of mitochondrial quality control systems, which in turn affects cellular energy metabolism and results in cellular dysfunction, accelerating the aging process. AMP-activated protein kinase (AMPK) and the mechanistic target of rapamycin complex 1 (mTORC1) are two central kinase complexes responsible for sensing intracellular nutrient levels, regulating metabolic homeostasis, modulating aging and play a crucial role in maintaining the homeostatic balance of mitochondria. Our previous studies found that the novel compound tetramethylpyrazine nitrone (TBN) can protect mitochondria via the AMPK/mTOR pathway in many animal models, extending healthy lifespan through the Nrf2 signaling pathway in nematodes. Building upon this foundation, we have posited a reasonable hypothesis, TBN can improve mitochondrial function to delay aging by regulating the AMPK/mTORC1 signaling pathway. This study focuses on the C. elegans, exploring the impact and underlying mechanisms of TBN on aging and mitochondrial function (especially the mitochondrial quality control system) during the aging process. The present studies demonstrated that TBN extends lifespan of wild-type nematodes and is associated with the AMPK/mTORC1 signaling pathway. TBN elevated ATP and NAD+ levels in aging nematodes while orchestrating mitochondrial biogenesis and mitophagy. Moreover, TBN was observed to significantly enhance normal activities during aging in C. elegans, such as mobility and pharyngeal pumping, concurrently impeding lipofuscin accumulation that were closely associated with AMPK and mTORC1. This study not only highlights the delayed effects of TBN on aging but also underscores its potential application in strategies aimed at improving mitochondrial function via the AMPK/mTOR pathway in C. elegans.
    Keywords:  AMPK; Aging; Lifespan; Mitochondrial function; mTOR
    DOI:  https://doi.org/10.1016/j.bbrc.2024.150220
  13. Autophagy. 2024 Jun 14.
    The different roles of V-ATPase a subunits in phagocytosis/endocytosis and autophagy.
    Qi Chen, Hanjing Kou, Doris Lou Demy, Wei Liu, Jianchao Li, Zilong Wen, Philippe Herbomel, Zhibin Huang, Wenqing Zhang, Jin Xu.
      Microglia are specialized macrophages responsible for the clearance of dead neurons and pathogens by phagocytosis and degradation. The degradation requires phagosome maturation and acidification provided by the vesicular- or vacuolar-type H+-translocating adenosine triphosphatase (V-ATPase), which is composed of the cytoplasmic V1 domain and the membrane-embedded Vo domain. The V-ATPase a subunit, an integral part of the Vo domain, has four isoforms in mammals. The functions of different isoforms on phagosome maturation in different cells/species remain controversial. Here we show that mutations of both the V-ATPase Atp6v0a1 and Tcirg1b/Atp6v0a3 subunits lead to the accumulation of phagosomes in zebrafish microglia. However, their mechanisms are different. The V-ATPase Atp6v0a1 subunit is mainly distributed in early and late phagosomes. Defects of this subunit lead to a defective transition from early phagosomes to late phagosomes. In contrast, The V-ATPase Tcirg1b/Atp6v0a3 subunit is primarily located on lysosomes and regulates late phagosome-lysosomal fusion. Defective Tcirg1b/Atp6v0a3, but not Atp6v0a1 subunit leads to reduced acidification and impaired macroautophagy/autophagy in microglia. We further showed that ATP6V0A1/a1 and TCIRG1/a3 subunits in mouse macrophages preferentially located in endosomes and lysosomes, respectively. Blocking these subunits disrupted early-to-late endosome transition and endosome-to-lysosome fusion, respectively. Taken together, our results highlight the essential and conserved roles played by different V-ATPase subunits in multiple steps of phagocytosis and endocytosis across various species.
    Keywords:  Autophagy; V-ATPase; microglia; phagosome maturation; zebrafish
    DOI:  https://doi.org/10.1080/15548627.2024.2366748
  14. Cell Commun Signal. 2024 Jun 11. 22(1): 320
    Targeting mTOR signaling pathways in multiple myeloma: biology and implication for therapy.
    Yanmeng Wang, Niels Vandewalle, Kim De Veirman, Karin Vanderkerken, Eline Menu, Elke De Bruyne.
      Multiple Myeloma (MM), a cancer of terminally differentiated plasma cells, is the second most prevalent hematological malignancy and is incurable due to the inevitable development of drug resistance. Intense protein synthesis is a distinctive trait of MM cells, supporting the massive production of clonal immunoglobulins or free light chains. The mammalian target of rapamycin (mTOR) kinase is appreciated as a master regulator of vital cellular processes, including regulation of metabolism and protein synthesis, and can be found in two multiprotein complexes, mTORC1 and mTORC2. Dysregulation of these complexes is implicated in several types of cancer, including MM. Since mTOR has been shown to be aberrantly activated in a large portion of MM patients and to play a role in stimulating MM cell survival and resistance to several existing therapies, understanding the regulation and functions of the mTOR complexes is vital for the development of more effective therapeutic strategies. This review provides a general overview of the mTOR pathway, discussing key discoveries and recent insights related to the structure and regulation of mTOR complexes. Additionally, we highlight findings on the mechanisms by which mTOR is involved in protein synthesis and delve into mTOR-mediated processes occurring in MM. Finally, we summarize the progress and current challenges of drugs targeting mTOR complexes in MM.
    Keywords:  Multiple myeloma; Protein synthesis; Targeted therapy; mTOR
    DOI:  https://doi.org/10.1186/s12964-024-01699-3
  15. Autophagy. 2024 Jun 14.
    Signal-sustained imaging of mitophagy with an Enzyme-Activatable Metabolic Lipid-Labeling Probe.
    Xiaoxue Zou, Shixiong Wen, Lichun Xu, Lei Gao, Xunxiang Wang, Xiao Hu, Jiahuai Han, Shoufa Han.
      Imaging of mitophagy is of significance as aberrant mitophagy is engaged in multiple diseases. Mitophagy has been imaged with synthetic or biotic pH sensors by reporting pH acidification en route delivery into lysosomes. To circumvent uncertainty of acidity-dependent signals, we herein report an enzyme-activatable probe covalently attached on mitochondrial inner membrane (ECAM) for signal-persist mitophagy imaging. ECAM is operated via ΔΨm-driven accumulation of Mito-proGreen in mitochondria and covalent linking of the trapped probe with azidophospholipids metabolically incorporated into the mitochondrial inner membrane. Upon mitophagy, ECAM is delivered into lysosomes and hydrolyzed by LNPEP/leucyl aminopeptidase, yielding turn-on green fluorescence that is immune to lysosomal acidity changes and stably retained in fixed cells. With ECAM, phorbol-12-myristate-13-acetate (PMA) was identified as a highly potent inducer of mitophagy. Overcoming signal susceptibility of pH probes and liability of ΔΨm probes to dissipation from stressed mitochondria, ECAM offers an attractive tool to study mitophagy and mitophagy-inducing therapeutic agents.
    Keywords:  Enzyme activation; fluorescence-on; metabolic lipid labeling; mitophagy imaging; ph-independent fluorescence
    DOI:  https://doi.org/10.1080/15548627.2024.2367192
  16. Front Immunol. 2024 ;15 1260439
    Dengue virus exploits autophagy vesicles and secretory pathways to promote transmission by human dendritic cells.
    Alexandra P M Cloherty, Anusca G Rader, Kharishma S Patel, Tracy-Jane T H D Eisden, Sterre van Piggelen, Renée R C E Schreurs, Carla M S Ribeiro.
      Dengue virus (DENV), transmitted by infected mosquitoes, is a major public health concern, with approximately half the world's population at risk for infection. Recent decades have increasing incidence of dengue-associated disease alongside growing frequency of outbreaks. Although promising progress has been made in anti-DENV immunizations, post-infection treatment remains limited to non-specific supportive treatments. Development of antiviral therapeutics is thus required to limit DENV dissemination in humans and to help control the severity of outbreaks. Dendritic cells (DCs) are amongst the first cells to encounter DENV upon injection into the human skin mucosa, and thereafter promote systemic viral dissemination to additional human target cells. Autophagy is a vesicle trafficking pathway involving the formation of cytosolic autophagosomes, and recent reports have highlighted the extensive manipulation of autophagy by flaviviruses, including DENV, for viral replication. However, the temporal profiling and function of autophagy activity in DENV infection and transmission by human primary DCs remains poorly understood. Herein, we demonstrate that mechanisms of autophagosome formation and extracellular vesicle (EV) release have a pro-viral role in DC-mediated DENV transmission. We show that DENV exploits early-stage canonical autophagy to establish infection in primary human DCs. DENV replication enhanced autophagosome formation in primary human DCs, and intrinsically-heightened autophagosome biogenesis correlated with relatively higher rates of DC susceptibility to DENV. Furthermore, our data suggest that viral replication intermediates co-localize with autophagosomes, while productive DENV infection introduces a block at the late degradative stages of autophagy in infected DCs but not in uninfected bystander cells. Notably, we identify for the first time that approximately one-fourth of DC-derived CD9/CD81/CD63+ EVs co-express canonical autophagy marker LC3, and demonstrate that DC-derived EV populations are an alternative, cell-free mechanism by which DCs promote DENV transmission to additional target sites. Taken together, our study highlights intersections between autophagy and secretory pathways during viral infection, and puts forward autophagosome accumulation and viral RNA-laden EVs as host determinants of DC-mediated DENV infection in humans. Host-directed therapeutics targeting autophagy and exocytosis pathways thus have potential to enhance DC-driven resistance to DENV acquisition and thereby limit viral dissemination by initial human target cells following mosquito-to-human transmission of DENV.
    Keywords:  autophagy; dendritic cells; dengue virus; extracellular vesicles; host-directed antivirals; secretory autophagy; viral evasion; viral transmission
    DOI:  https://doi.org/10.3389/fimmu.2024.1260439
  17. Vet Microbiol. 2024 Jun 06. pii: S0378-1135(24)00172-X. [Epub ahead of print]295 110150
    JEV infection leads to dysfunction of lysosome by downregulating the expression of LAMP1 and LAMP2.
    Xingmiao Yang, Zheng Wang, Shengda Xie, Zhenjie Liang, Ning Wei, Junhui Pan, Yundi Zhao, Ruibing Cao.
      Japanese Encephalitis Virus (JEV), the predominant cause of viral encephalitis in many Asian countries, affects approximately 68,000 people annually. Lysosomes are dynamic structures that regulate cellular metabolism by mediating lysosomal biogenesis and autophagy. Here, we showed that lysosome-associated membrane protein 1 (LAMP1) and LAMP2 were downregulated in cells after JEV infection, resulting in a decrease in the quantity of acidified lysosomes and impaired lysosomal catabolism. What's more, JEV nonstructural protein 4B plays key roles in the reduction of LAMP1/2 via the autophagy-lysosome pathway. JEV NS4B also promoted abnormal aggregation of SLA-DR, an important component of the swine MHC-II molecule family involved in antigen presentation and CD4+ cell activation initiation. Mechanistically, NS4B localized to the ER during JEV infection and interacted with GRP78, leading to the activation of ER stress-mediated autophagy. The 131-204 amino acid (aa) region of NS4B is essential for autophagy induction and LAMP1/2 reduction. In summary, our findings reveal a novel pathway by which JEV induces autophagy and disrupts lysosomal function.
    Keywords:  Autophagy; JEV; LAMP1; LAMP2; Lysosome; NS4B; SLA-DR
    DOI:  https://doi.org/10.1016/j.vetmic.2024.110150
  18. Circ Res. 2024 Jun 14.
    The Ubiquitin Ligase RBX2/SAG Regulates Mitochondrial Ubiquitination and Mitophagy.
    Wenjuan Wang, Ermin Li, Jianqiu Zou, Chen Qu, Juan Ayala, Yuan Wen, Md Sadikul Islam, Neal L Weintraub, David J Fulton, Qiangrong Liang, Jiliang Zhou, Jinbao Liu, Jie Li, Yi Sun, Huabo Su.
       BACKGROUND: Clearance of damaged mitochondria via mitophagy is crucial for cellular homeostasis. Apart from Parkin, little is known about additional Ub (ubiquitin) ligases that mediate mitochondrial ubiquitination and turnover, particularly in highly metabolically active organs such as the heart.
    METHODS: In this study, we have combined in silico analysis and biochemical assay to identify CRL (cullin-RING ligase) 5 as a mitochondrial Ub ligase. We generated cardiomyocytes and mice lacking RBX2 (RING-box protein 2; also known as SAG [sensitive to apoptosis gene]), a catalytic subunit of CRL5, to understand the effects of RBX2 depletion on mitochondrial ubiquitination, mitophagy, and cardiac function. We also performed proteomics analysis and RNA-sequencing analysis to define the impact of loss of RBX2 on the proteome and transcriptome.
    RESULTS: RBX2 and CUL (cullin) 5, 2 core components of CRL5, localize to mitochondria. Depletion of RBX2 inhibited mitochondrial ubiquitination and turnover, impaired mitochondrial membrane potential and respiration, increased cardiomyocyte cell death, and has a global impact on the mitochondrial proteome. In vivo, deletion of the Rbx2 gene in adult mouse hearts suppressed mitophagic activity, provoked accumulation of damaged mitochondria in the myocardium, and disrupted myocardial metabolism, leading to the rapid development of dilated cardiomyopathy and heart failure. Similarly, ablation of RBX2 in the developing heart resulted in dilated cardiomyopathy and heart failure. The action of RBX2 in mitochondria is not dependent on Parkin, and Parkin gene deletion had no impact on the onset and progression of cardiomyopathy in RBX2-deficient hearts. Furthermore, RBX2 controls the stability of PINK1 in mitochondria.
    CONCLUSIONS: These findings identify RBX2-CRL5 as a mitochondrial Ub ligase that regulates mitophagy and cardiac homeostasis in a Parkin-independent, PINK1-dependent manner.
    Keywords:  heart failure; mitochondria; mitophagy; protein kinases; ubiquitination
    DOI:  https://doi.org/10.1161/CIRCRESAHA.124.324285
  19. Cell. 2024 Jun 05. pii: S0092-8674(24)00526-9. [Epub ahead of print]
    MTFP1 controls mitochondrial fusion to regulate inner membrane quality control and maintain mtDNA levels.
    Luis Carlos Tábara, Stephen P Burr, Michele Frison, Suvagata R Chowdhury, Vincent Paupe, Yu Nie, Mark Johnson, Jara Villar-Azpillaga, Filipa Viegas, Mayuko Segawa, Hanish Anand, Kasparas Petkevicius, Patrick F Chinnery, Julien Prudent.
      Mitochondrial dynamics play a critical role in cell fate decisions and in controlling mtDNA levels and distribution. However, the molecular mechanisms linking mitochondrial membrane remodeling and quality control to mtDNA copy number (CN) regulation remain elusive. Here, we demonstrate that the inner mitochondrial membrane (IMM) protein mitochondrial fission process 1 (MTFP1) negatively regulates IMM fusion. Moreover, manipulation of mitochondrial fusion through the regulation of MTFP1 levels results in mtDNA CN modulation. Mechanistically, we found that MTFP1 inhibits mitochondrial fusion to isolate and exclude damaged IMM subdomains from the rest of the network. Subsequently, peripheral fission ensures their segregation into small MTFP1-enriched mitochondria (SMEM) that are targeted for degradation in an autophagic-dependent manner. Remarkably, MTFP1-dependent IMM quality control is essential for basal nucleoid recycling and therefore to maintain adequate mtDNA levels within the cell.
    Keywords:  IMM quality control; IMM remodeling; MTFP1; autophagy; fission and fusion; mitochondria; mitochondrial dynamics; mitophagy; mtDNA
    DOI:  https://doi.org/10.1016/j.cell.2024.05.017
  20. Res Sq. 2024 May 30. pii: rs.3.rs-4407236. [Epub ahead of print]
    Human tNeurons reveal aging-linked proteostasis deficits driving Alzheimer's phenotypes.
    Judith Frydman, Ching-Chieh Chou, Ryan Vest, Miguel Prado, Joshua Wilson-Grady, Joao Paulo, Yohei Shibuya, Patricia Moran Losada, Ting-Ting Lee, Jian Luo, Steven Gygi, Jeffrey Kelly, Daniel Finley, Marius Wernig, Tony Wyss-Coray.
      Aging is a prominent risk factor for Alzheimer's disease (AD), but the cellular mechanisms underlying neuronal phenotypes remain elusive. Both accumulation of amyloid plaques and neurofibrillary tangles in the brain1 and age-linked organelle deficits 2-7 are proposed as causes of AD phenotypes but the relationship between these events is unclear. Here, we address this question using a transdifferentiated neuron (tNeuron) model directly from human dermal fibroblasts. Patient-derived tNeurons retain aging hallmarks and exhibit AD-linked deficits. Quantitative tNeuron proteomic analyses identify aging and AD-linked deficits in proteostasis and organelle homeostasis, particularly affecting endosome-lysosomal components. The proteostasis and lysosomal homeostasis deficits in aged tNeurons are exacerbated in sporadic and familial AD tNeurons, promoting constitutive lysosomal damage and defects in ESCRT-mediated repair. We find deficits in neuronal lysosomal homeostasis lead to inflammatory cytokine secretion, cell death and spontaneous development of Aß and phospho-Tau deposits. These proteotoxic inclusions co-localize with lysosomes and damage markers and resemble inclusions in brain tissue from AD patients and APP-transgenic mice. Supporting the centrality of lysosomal deficits driving AD phenotypes, lysosome-function enhancing compounds reduce AD-associated cytokine secretion and Aβ deposits. We conclude that proteostasis and organelle deficits are upstream initiating factors leading to neuronal aging and AD phenotypes.
    DOI:  https://doi.org/10.21203/rs.3.rs-4407236/v1
  21. Chem Biol Interact. 2024 Jun 12. pii: S0009-2797(24)00256-4. [Epub ahead of print] 111110
    Polydatin: a potential NAFLD therapeutic drug that regulates mitochondrial autophagy through SIRT3-FOXO3-BNIP3 and PINK1-PRKN mechanisms - a network pharmacology and experimental investigation.
    Jing He, Yi-Cai Qian, Ying-Chuan Yin, Jing-Rui Kang, Tian-Rong Pan.
      Non-alcoholic fatty liver disease (NAFLD) is a prevalent chronic liver disorder that is linked to metabolic syndrome, mitochondrial dysfunction and impaired autophagy. Polydatin (PD), a natural polyphenol from Polygonum cuspidatum, exhibits various pharmacological effects and protects against NAFLD. The aim of this study was to reveal the molecular mechanisms and therapeutic potential of PD for NAFLD, with a focus on the role of mitochondrial autophagy mediated by sirtuin 3 (SIRT3), fork-head box O3 (FOXO3) and BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 (BNIP3), and by PTEN-induced putative kinase 1 (PINK1) and parkin (PRKN). We combined network pharmacology analysis, animal models and cell culture experiments to show that PD could regulate the mitochondrial autophagy pathway by modulating several key genes related to mitochondrial function, and ameliorate the liver function, histopathology and mitochondrial biogenesis of NAFLD mice and hepatocytes by activating the SIRT3-FOXO3-BNIP3 axis and the PINK1-PRKN-dependent mechanism of mitochondrial autophagy. We also identified the core targets of PD, including SIRT3, FOXO3A, CASP3, PARKIN, EGFR, STAT3, MMP9 and PINK, and confirmed that silencing SIRT3 could significantly attenuate the beneficial effect of PD. This study provided novel theoretical and experimental support for PD as a promising candidate for NAFLD treatment, and also suggested new avenues and methods for investigating the role of mitochondrial autophagy in the pathogenesis and intervention of NAFLD.
    Keywords:  Mitochondrial autophagy; NAFLD; PINK1-PRKN; Polydatin; SIRT3-FOXO3
    DOI:  https://doi.org/10.1016/j.cbi.2024.111110
  22. Exp Cell Res. 2024 Jun 07. pii: S0014-4827(24)00209-X. [Epub ahead of print] 114118
    Altered Autophagic Flux in GNE mutant cells of Indian Origin: potential drug target for GNE Myopathy.
    Jyoti Oswalia, Shagun Singh, Vaishali Gautam, Ranjana Arya.
      Autophagy phenomenon in the cell maintains proteostasis balance by eliminating damaged organelles and protein aggregates. Imbalance in autophagic flux may cause accumulation of protein aggregates in various neurodegenerative disorders. Regulation of autophagy by either calcium or chaperone play a key role in the removal of protein aggregates from the cell. The neuromuscular rare genetic disorder, GNE Myopathy, is characterized by accumulation of rimmed vacuoles having protein aggregates of β-amyloid and tau that may result from altered autophagic flux. In the present study, the autophagic flux was deciphered in HEK cell-based model for GNE Myopathy harbouring GNE mutations of Indian origin. The refolding activity of HSP70 chaperone was found to be reduced in GNE mutant cells compared to wild type controls. The autophagic markers LC3II/I ratio was altered with increased number of autophagosome formation in GNE mutant cells compared to wild type cells. The cytosolic calcium levels were also increased in GNE mutant cells of Indian origin. Interestingly, treatment of GNE mutant cells with HSP70 activator, BGP-15, restored the expression and refolding activity of HSP70 along with autophagosome formation. Treatment with calcium chelator, BAPTA-AM restored the cytoplasmic calcium levels and autophagosome formation but not LC3II/I ratio significantly. Our study provides insights towards GNE mutation specific response for autophagy regulation and opens up a therapeutic advancement area in calcium signalling and HSP70 function for GNE related Myopathy.
    Keywords:  GNE Myopathy; autophagy; calcium homeostasis; rare genetic disease
    DOI:  https://doi.org/10.1016/j.yexcr.2024.114118
  23. Mov Disord. 2024 Jun 10.
    Diverse Functions of Parkin in Midbrain Dopaminergic Neurons.
    Pingping Song, Dimitri Krainc.
      Parkinson's disease (PD) is characterized by preferential degeneration of midbrain dopaminergic neurons that contributes to its typical clinical manifestation. Mutations in the parkin gene (PARK2) represent a relatively common genetic cause of early onset PD. Parkin has been implicated in PINK1-dependent mitochondrial quantity control by targeting dysfunctional mitochondria to lysosomes via mitophagy. Recent evidence suggests that parkin can be activated in PINK1-independent manner to regulate synaptic function in human dopaminergic neurons. Neuronal activity triggers CaMKII-mediated activation of parkin and its recruitment to synaptic vesicles where parkin promotes binding of synaptojanin-1 to endophilin A1 and facilitates vesicle endocytosis. In PD patient neurons, disruption of this pathway on loss of parkin leads to defective recycling of synaptic vesicles and accumulation of toxic oxidized dopamine that at least in part explains preferential vulnerability of midbrain dopaminergic neurons. These findings suggest a convergent mechanism for PD-linked mutations in parkin, synaptojanin-1, and endophilin A1 and highlight synaptic dysfunction as an early pathogenic event in PD. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
    Keywords:  Parkin functions; Parkinson's disease; dopaminergic neurons; synaptic terminal
    DOI:  https://doi.org/10.1002/mds.29890
  24. Neurochem Res. 2024 Jun 08.
    The Role and Mechanism of Ambra1-Mediated Mitophagy in TDCPP-Exposed Mouse Hippocampal Neurons.
    Xiaowei Zhang, Chuzhi Lin, Hengfang Hu, Wei Zhao, Guanlin Li, Yun Xia, Nengzhou Chen.
      Tri(1,3-dichloro-2-propyl)phosphate (TDCPP) is one of the most widely used organophosphorus flame retardants in consumer products. TDCPP has been confirmed to be neurotoxic, but its mechanism has not been clarified and may be related to mitophagy. AMBRA1 can promote neurological autophagy, but whether AMBRA1 is involved in the mechanism of TDCPP-induced neurotoxicity has not been elucidated. In this study, the optimal neuronal damage model was established by exposing mice hippocampal neurons to TDCPP. Furthermore, on the basis of this model, siRNA was used to knock down AMBRA1. Combined with qRT-PCR and Western blot techniques, we identified AMBRA1-mediated mitophagy-induced neuronal damage in vitro mechanism. The experimental results indicated that TDCPP treatment for 24 h led to a decrease in the cell viability of mouse hippocampal neurons, causing neuronal damage. Meanwhile, TDCPP exposure increased autophagy marker proteins p62 and LC3B, and down-regulated mitochondrial DNA ND1 damage and TOMM20 protein, suggesting that TDCPP exposure promoted mitophagy. In addition, TDCPP exposure led to changes in the expression of AMBRA1 and the key factors of mitophagy, FUNDC1, PINK1, and PARKIN, whereas mitophagy was inhibited after knockdown of AMBRA1. The research results indicated that exposure to TDCPP induced neuronal damage and promoted mitophagy. The mechanism may be that AMBRA1 promoted mitophagy in neuronal cells through the PARKIN-dependent/non-dependent pathway. This study revealed the toxic effects of TDCPP on the nervous system and its potential molecular mechanisms, which provided important clues for further understanding the mechanism of action of AMBAR1-mediated mitophagy.
    Keywords:  AMBRA1; Mitophagy; Neuronal damage; TDCPP
    DOI:  https://doi.org/10.1007/s11064-024-04160-6
  25. Cancer Lett. 2024 Jun 11. pii: S0304-3835(24)00418-X. [Epub ahead of print] 217024
    Lysosomal exocytosis: From cell protection to protumoral functions.
    Marie-Charlotte Trojani, Sabine Santucci-Darmanin, Véronique Breuil, Georges F Carle, Valérie Pierrefite-Carle.
      Lysosomes are single membrane bounded group of acidic organelles that can be involved in a process called lysosomal exocytosis which leads to the extracellular release of their content. Lysosomal exocytosis is required for plasma membrane repair or remodeling events such as bone resorption, antigen presentation or mitosis, and for protection against toxic agents such as heavy metals. Recently, it has been showed that to fulfill this protective role, lysosomal exocytosis needs some autophagic proteins, in an autophagy-independent manner. In addition to these crucial physiological roles, lysosomal exocytosis plays a major protumoral role in various cancers. This effect is exerted through tumor microenvironment modifications, including extracellular matrix remodeling, acidosis, oncogenic and profibrogenic signals. This review provides a comprehensive overview of the different elements released in the microenvironment during lysosomal exocytosis, i.e. proteases, exosomes, and protons, and their effects in the context of tumor development and treatment.
    DOI:  https://doi.org/10.1016/j.canlet.2024.217024
  26. Cell Div. 2024 Jun 12. 19(1): 20
    Advances in SIRT3 involvement in regulating autophagy-related mechanisms.
    Shuangyun Xi, Weijun Chen, Yong Ke.
      The silencing regulatory factor 2-like protein 3 (SIRT3) is a nicotinamide adenine dinucleotide (NAD+) dependent deacetylase located primarily in the mitochondria. This protein plays an important role in oxidative stress, energy metabolism, and autophagy in multicellular organisms. Autophagy (macroautophagy) is primarily a cytoprotective mechanism necessary for intracellular homeostasis and the synthesis, degradation, and recycling of cellular products. Autophagy can influence the progression of several neural, cardiac, hepatic, and renal diseases and can also contribute to the development of fibrosis, diabetes, and many types of cancer. Recent studies have shown that SIRT3 has an important role in regulating autophagy. Therefore in this study, we aimed to perform a literature review to summarize the role of SIRT3 in the regulation of cellular autophagy. The findings of this study could be used to identify new drug targets for SIRT3-related diseases. Methods: A comprehensive literature review of the mechanism involved behind SIRT3 and autophagy-related diseases was performed. Relevant literature published in Pubmed and Web of Science up to July 2023 was identified using the keywords "silencing regulatory factor 2-like protein 3", "SIRT3" and "autophagy".
    Keywords:  Autophagy; Deacetylase; SIRT3; Signaling pathway
    DOI:  https://doi.org/10.1186/s13008-024-00124-y
  27. J Clin Invest. 2024 Jun 13. pii: e165814. [Epub ahead of print]
    C16ORF70/Mytho promotes healthy ageing in C. elegans and prevents cellular senescence in mammals.
    Anais Franco-Romero, Valeria Morbidoni, Giulia Milan, Roberta Sartori, Jesper Wulff, Vanina Romanello, Andrea Armani, Leonardo Salviati, Maria Conte, Stefano Salvioli, Claudio Franceschi, Viviana Buonomo, Casey O Swoboda, Paolo Grumati, Luca Pannone, Simone Martinelli, Harold Bj Jefferies, Ivan Dikic, Jennifer van der Laan, Filipe Cabreiro, Douglas P Millay, Sharon A Tooze, Eva Trevisson, Marco Sandri.
      The identification of genes that confer either extension of lifespan or accelerate age-related decline was a step forward in understanding the mechanisms of ageing and revealed that it is partially controlled by genetics and transcriptional programs. Here we discovered that the human DNA sequence C16ORF70 encoded for a protein, named MYTHO (Macroautophagy and YouTH Optimizer), which controls life- and health-span. MYTHO protein is conserved from C. elegans to humans and its mRNA was upregulated in aged mice and elderly people. Deletion of the ortholog myt-1 gene in C. elegans dramatically shortened lifespan and decreased animal survival upon exposure to oxidative stress. Mechanistically, MYTHO is required for autophagy likely because it acts as a scaffold that binds WIPI2 and BCAS3 to recruit and assemble the conjugation system at the phagophore, the nascent autophagosome. We conclude that MYTHO is a transcriptionally regulated initiator of autophagy that is central in promoting stress resistance and healthy ageing.
    Keywords:  Aging; Autophagy; Cell biology; Cellular senescence; Skeletal muscle
    DOI:  https://doi.org/10.1172/JCI165814
  28. Ann Neurol. 2024 Jun 15.
    Mutations in CLCN6 as a Novel Genetic Cause of Neuronal Ceroid Lipofuscinosis.
    Hailan He, Xiaoshuang Cao, Fang He, Wen Zhang, Xiaole Wang, Pan Peng, Changning Xie, Fei Yin, Dengfeng Li, Jiada Li, Minghui Wang, Malte Klüssendorf, Thomas J Jentsch, Tobias Stauber, Jing Peng.
       OBJECTIVE: The aim of this study was to explore the pathogenesis of CLCN6-related disease and to assess whether its Cl-/H+-exchange activity is crucial for the biological role of ClC-6.
    METHODS: We performed whole-exome sequencing on a girl with development delay, intractable epilepsy, behavioral abnormities, retinal dysfunction, progressive brain atrophy, suggestive of neuronal ceroid lipofuscinoses (NCLs). We generated and analyzed the first knock-in mouse model of a patient variant (p.E200A) and compared it with a Clcn6-/- mouse model. Additional functional tests were performed with heterologous expression of mutant ClC-6.
    RESULTS: We identified a de novo heterozygous p.E200A variant in the proband. Expression of disease-causing ClC-6E200A or ClC-6Y553C mutants blocked autophagic flux and activated transcription factors EB (TFEB) and E3 (TFE3), leading to autophagic vesicle and cholesterol accumulation. Such alterations were absent with a transport-deficient ClC-6E267A mutant. Clcn6E200A/+ mice developed severe neurodegeneration with typical features of NCLs. Mutant ClC-6E200A, but not loss of ClC-6 in Clcn6-/- mice, increased lysosomal biogenesis by suppressing mTORC1-TFEB signaling, blocked autophagic flux through impairing lysosomal function, and increased apoptosis. Carbohydrate and lipid deposits accumulated in Clcn6E200A/+ brain, while only lipid storage was found in Clcn6-/- brain. Lysosome dysfunction, autophagy defects, and gliosis were early pathogenic events preceding neuron loss.
    INTERPRETATION: CLCN6 is a novel genetic cause of NCLs, highlighting the importance of considering CLCN6 mutations in the diagnostic workup for molecularly undefined forms of NCLs. Uncoupling of Cl- transport from H+ countertransport in the E200A mutant has a dominant effect on the autophagic/lysosomal pathway. ANN NEUROL 2024.
    DOI:  https://doi.org/10.1002/ana.27002
  29. Sci Rep. 2024 06 13. 14(1): 13653
    Partitioning into ER membrane microdomains impacts autophagic protein turnover during cellular aging.
    Simon Prokisch, Sabrina Büttner.
      Eukaryotic membranes are compartmentalized into distinct micro- and nanodomains that rearrange dynamically in response to external and internal cues. This lateral heterogeneity of the lipid bilayer and associated clustering of distinct membrane proteins contribute to the spatial organization of numerous cellular processes. Here, we show that membrane microdomains within the endoplasmic reticulum (ER) of yeast cells are reorganized during metabolic reprogramming and aging. Using biosensors with varying transmembrane domain length to map lipid bilayer thickness, we demonstrate that in young cells, microdomains of increased thickness mainly exist within the nuclear ER, while progressing cellular age drives the formation of numerous microdomains specifically in the cortical ER. Partitioning of biosensors with long transmembrane domains into these microdomains increased protein stability and prevented autophagic removal. In contrast, reporters with short transmembrane domains progressively accumulated at the membrane contact site between the nuclear ER and the vacuole, the so-called nucleus-vacuole junction (NVJ), and were subjected to turnover via selective microautophagy occurring specifically at these sites. Reporters with long transmembrane domains were excluded from the NVJ. Our data reveal age-dependent rearrangement of the lateral organization of the ER and establish transmembrane domain length as a determinant of membrane contact site localization and autophagic degradation.
    DOI:  https://doi.org/10.1038/s41598-024-64493-8
  30. Autophagy. 2024 Jun 14.
    Activation of BK channels prevents diabetes-induced osteopenia by regulating mitochondrial Ca2+ and SLC25A5/ANT2-PINK1-PRKN-mediated mitophagy.
    Lan Jiang, Haidong He, Yuyan Tang, Jiawei Li, Svetlana Reilly, Hong Xin, Zhiping Li, Hui Cai, Xuemei Zhang.
      Osteopenia and osteoporosis are among the most common metabolic bone diseases and represent major public health problems, with sufferers having an increased fracture risk. Diabetes is one of the most common diseases contributing to osteopenia and osteoporosis. However, the mechanisms underlying diabetes-induced osteopenia and osteoporosis remain unclear. Bone reconstruction, including bone formation and absorption, is a dynamic process. Large-conductance Ca2+-activated K+ channels (BK channels) regulate the function of bone marrow-derived mesenchymal stem cells, osteoblasts, and osteoclasts. Our previous studies revealed the relationship between BK channels and the function of osteoblasts via various pathways under physiological conditions. In this study, we reported a decrease in the expression of BK channels in mice with diabetes-induced osteopenia. BK deficiency enhanced mitochondrial Ca2+ and activated classical PINK1 (PTEN induced putative kinase 1)-PRKN/Parkin (parkin RBR E3 ubiquitin protein ligase)-dependent mitophagy, whereas the upregulation of BK channels inhibited mitophagy in osteoblasts. Moreover, SLC25A5/ANT2 (solute carrier family 25 (mitochondrial carrier, adenine nucleotide translocator), member 5), a critical inner mitochondrial membrane protein participating in PINK1-PRKN-dependent mitophagy, was also regulated by BK channels. Overall, these data identified a novel role of BK channels in regulating mitophagy in osteoblasts, which might be a potential target for diabetes-induced bone diseases.
    Keywords:  Adenine nucleotide translocator; BK channel; PINK1-PRKN pathway; mitochondrial calcium; mitophagy
    DOI:  https://doi.org/10.1080/15548627.2024.2367184
  31. Sci Rep. 2024 06 12. 14(1): 13596
    REST-dependent downregulation of von Hippel-Lindau tumor suppressor promotes autophagy in SHH-medulloblastoma.
    Ashutosh Singh, Donghang Cheng, Jyothishmathi Swaminathan, Yanwen Yang, Yan Zheng, Nancy Gordon, Vidya Gopalakrishnan.
      The RE1 silencing transcription factor (REST) is a driver of sonic hedgehog (SHH) medulloblastoma genesis. Our previous studies showed that REST enhances cell proliferation, metastasis and vascular growth and blocks neuronal differentiation to drive progression of SHH medulloblastoma tumors. Here, we demonstrate that REST promotes autophagy, a pathway that is found to be significantly enriched in human medulloblastoma tumors relative to normal cerebella. In SHH medulloblastoma tumor xenografts, REST elevation is strongly correlated with increased expression of the hypoxia-inducible factor 1-alpha (HIF1α)-a positive regulator of autophagy, and with reduced expression of the von Hippel-Lindau (VHL) tumor suppressor protein - a component of an E3 ligase complex that ubiquitinates HIF1α. Human SHH-medulloblastoma tumors with higher REST expression exhibit nuclear localization of HIF1α, in contrast to its cytoplasmic localization in low-REST tumors. In vitro, REST knockdown promotes an increase in VHL levels and a decrease in cytoplasmic HIF1α protein levels, and autophagy flux. In contrast, REST elevation causes a decline in VHL levels, as well as its interaction with HIF1α, resulting in a reduction in HIF1α ubiquitination and an increase in autophagy flux. These data suggest that REST elevation promotes autophagy in SHH medulloblastoma cells by modulating HIF1α ubiquitination and stability in a VHL-dependent manner. Thus, our study is one of the first to connect VHL to REST-dependent control of autophagy in a subset of medulloblastomas.
    Keywords:  Autophagy; Hypoxia-inducible factor 1-alpha (HIF1α); Medulloblastoma; REST; Ubiquitination; Von Hippel-Lindau (VHL)
    DOI:  https://doi.org/10.1038/s41598-024-63371-7
  32. Autophagy. 2024 Jun 14.
    The autophagy protein RUBCNL/PACER represses RIPK1 kinase-dependent apoptosis and necroptosis.
    Diego Rojas-Rivera, Sebastián Beltrán, Francisco Muñoz-Carvajal, Pablo Ahumada-Montalva, Lorena Abarzúa, Laura Gomez, Fernanda Hernandez, Cristian A Bergmann, Luis Labrador, Melissa Calegaro-Nassif, Mathieu J M Bertrand, Patricio A Manque, Ute Woehlbier.
      Mesenchymal stem cells (MSCs) are used in cell therapy; nonetheless, their application is limited by their poor survival after transplantation in a proinflammatory microenvironment. Macroautophagy/autophagy activation in MSCs constitutes a stress adaptation pathway, promoting cellular homeostasis. Our proteomics data indicate that RUBCNL/PACER (RUN and cysteine rich domain containing beclin 1 interacting protein like), a positive regulator of autophagy, is also involved in cell death. Hence, we screened MSC survival upon various cell death stimuli under loss or gain of function of RUBCNL. MSCs were protected from TNF (tumor necrosis factor)-induced regulated cell death when RUBCNL was expressed. TNF promotes inflammation by inducing RIPK1 kinase-dependent apoptosis or necroptosis. We determine that MSCs succumb to RIPK1 kinase-dependent apoptosis upon TNF sensing and necroptosis when caspases are inactivated. We show that RUBCNL is a negative regulator of both RIPK1-dependent apoptosis and necroptosis. Furthermore, RUBCNL mutants that lose the ability to regulate autophagy, retain their function in negatively regulating cell death. We also found that RUBCNL forms a complex with RIPK1, which disassembles in response to TNF. In line with this finding, RUBCNL expression limits assembly of RIPK1-TNFRSF1A/TNFR1 complex I, suggesting that complex formation between RUBCNL and RIPK1 represses TNF signaling. These results provide new insights into the crosstalk between the RIPK1-mediated cell death and autophagy machineries and suggest that RUBCNL, due to its functional duality in autophagy and apoptosis/necroptosis, could be targeted to improve the therapeutic efficacy of MSCs.
    Keywords:  Cell death; KIAA0226L; Mesenchymal stem cells; Necrostatin 1s; TNF; TNFR1
    DOI:  https://doi.org/10.1080/15548627.2024.2367923
  33. Arch Gerontol Geriatr. 2024 Jun 04. pii: S0167-4943(24)00198-5. [Epub ahead of print]125 105522
    Mitochondrial quality control dysfunction in osteoarthritis: Mechanisms, therapeutic strategies & future prospects.
    Chiyuen Cheung, Shaoqin Tu, Yi Feng, Chuiming Wan, Hong Ai, Zheng Chen.
      Osteoarthritis (OA) is a prevalent chronic joint disease characterized by articular cartilage degeneration, pain, and disability. Emerging evidence indicates that mitochondrial quality control dysfunction contributes to OA pathogenesis. Mitochondria are essential organelles to generate cellular energy via oxidative phosphorylation and regulate vital processes. Impaired mitochondria can negatively impact cellular metabolism and result in the generation of harmful reactive oxygen species (ROS). Dysfunction in mitochondrial quality control mechanisms has been increasingly linked to OA onset and progression. This review summarizes current knowledge on the role of mitochondrial quality control disruption in OA, highlighting disturbed mitochondrial dynamics, impaired mitochondrial biogenesis, antioxidant defenses and mitophagy. The review also discusses potential therapeutic strategies targeting mitochondrial Quality Control in OA, offering future perspectives on advancing OA therapeutic strategies.
    Keywords:  Mitochondrial dysfunction; Mitochondrial quality control; Mitophagy; Osteoarthritis; Oxidative stress
    DOI:  https://doi.org/10.1016/j.archger.2024.105522
  34. Sci Rep. 2024 06 10. 14(1): 13258
    Alpha-Hederin induces incomplete autophagic injury in non-small cell lung cancer by interfering with the lysosomal acidification.
    Feng Jin, Xiaomin Jiang, Xiaochen Ni, Shilong Yu, Feng Wu, Xinlin Shi, Defang Mao, Haibo Wang, Qingtong Shi, Yanqing Liu, Qin Xu.
      Lung cancer is the most common oncological disease worldwide, with non-small cell lung cancer accounting for approximately 85% of lung cancer cases. α-Hederin is a monodesmosidic triterpenoid saponin isolated from the leaves of Hedera helix L. or Nigella sativa and has been extensively studied for its antitumor activity against a variety of tumor cells. It has been suggested that α-Hederin is a potential regulator of autophagy and has high promise for application. However, the specific mechanism and characteristics of α-Hederin in regulating autophagy are not well understood. In this study, we confirmed the potential of α-Hederin application in lung cancer treatment and comprehensively explored the mechanism and characteristics of α-Hederin in regulating autophagy in lung cancer cells. Our results suggest that α-Hederin is an incomplete autophagy inducer that targets mTOR to activate the classical autophagic pathway, inhibits lysosomal acidification without significantly affecting the processes of autophagosome transport, lysosome biogenesis, autophagosome and lysosome fusion, and finally leads to impaired autophagic flux and triggers autophagic damage in NSCLC.
    Keywords:  Antitumor; Incomplete autophagy; Lysosomal acidification; Non-small cell lung cancer; α-Hederin
    DOI:  https://doi.org/10.1038/s41598-024-63348-6
  35. Acta Neuropathol Commun. 2024 Jun 08. 12(1): 90
    Mitochondrial alterations in fibroblasts from sporadic Alzheimer's disease (AD) patients correlate with AD-related clinical hallmarks.
    Fanny Eysert, Paula-Fernanda Kinoshita, Julien Lagarde, Sandra Lacas-Gervais, Laura Xicota, Guillaume Dorothée, Michel Bottlaender, Frédéric Checler, Marie-Claude Potier, Marie Sarazin, Mounia Chami.
      Mitochondrial dysfunctions are key features of Alzheimer's disease (AD). The occurrence of these disturbances in the peripheral cells of AD patients and their potential correlation with disease progression are underinvestigated. We studied mitochondrial structure, function and mitophagy in fibroblasts from healthy volunteers and AD patients at the prodromal (AD-MCI) or demented (AD-D) stages. We carried out correlation studies with clinical cognitive scores, namely, (i) Mini-Mental State Examination (MMSE) and (ii) Dementia Rating-Scale Sum of Boxes (CDR-SOB), and with (iii) amyloid beta (Aβ) plaque burden (PiB-PET imaging) and (iv) the accumulation of peripheral amyloid precursor protein C-terminal fragments (APP-CTFs). We revealed alterations in mitochondrial structure as well as specific mitochondrial dysfunction signatures in AD-MCI and AD-D fibroblasts and revealed that defective mitophagy and autophagy are linked to impaired lysosomal activity in AD-D fibroblasts. We reported significant correlations of a subset of these dysfunctions with cognitive decline, AD-related clinical hallmarks and peripheral APP-CTFs accumulation. This study emphasizes the potential use of peripheral cells for investigating AD pathophysiology.
    Keywords:  Alzheimer’s disease; Biomarker; Clinical correlations; Fibroblasts; Mitochondria; Mitophagy
    DOI:  https://doi.org/10.1186/s40478-024-01807-x
  36. Front Mol Biosci. 2024 ;11 1378656
    Cleavage of Hsp70.1 causes lysosomal cell death under stress conditions.
    Tetsumori Yamashima, Daria Mochly-Rosen, Soichi Wakatsuki, Eishiro Mizukoshi, Takuya Seike, Isabel Maria Larus, Che-Hong Chen, Miho Takemura, Hisashi Saito, Akihiro Ohashi.
      Autophagy mediates the degradation of intracellular macromolecules and organelles within lysosomes. There are three types of autophagy: macroautophagy, microautophagy, and chaperone-mediated autophagy. Heat shock protein 70.1 (Hsp70.1) exhibits dual functions as a chaperone protein and a lysosomal membrane stabilizer. Since chaperone-mediated autophagy participates in the recycling of ∼30% cytosolic proteins, its disorder causes cell susceptibility to stress conditions. Cargo proteins destined for degradation such as amyloid precursor protein and tau protein are trafficked by Hsp70.1 from the cytosol into lysosomes. Hsp70.1 is composed of an N-terminal nucleotide-binding domain (NBD) and a C-terminal domain that binds to cargo proteins, termed the substrate-binding domain (SBD). The NBD and SBD are connected by the interdomain linker LL1, which modulates the allosteric structure of Hsp70.1 in response to ADP/ATP binding. After the passage of the Hsp70.1-cargo complex through the lysosomal limiting membrane, high-affinity binding of the positive-charged SBD with negative-charged bis(monoacylglycero)phosphate (BMP) at the internal vesicular membranes activates acid sphingomyelinase to generate ceramide for stabilizing lysosomal membranes. As the integrity of the lysosomal limiting membrane is critical to ensure cargo protein degradation within the acidic lumen, the disintegration of the lysosomal limiting membrane is lethal to cells. After the intake of high-fat diets, however, β-oxidation of fatty acids in the mitochondria generates reactive oxygen species, which enhance the oxidation of membrane linoleic acids to produce 4-hydroxy-2-nonenal (4-HNE). In addition, 4-HNE is produced during the heating of linoleic acid-rich vegetable oils and incorporated into the body via deep-fried foods. This endogenous and exogenous 4-HNE synergically causes an increase in its serum and organ levels to induce carbonylation of Hsp70.1 at Arg469, which facilitates its conformational change and access of activated μ-calpain to LL1. Therefore, the cleavage of Hsp70.1 occurs prior to its influx into the lysosomal lumen, which leads to lysosomal membrane permeabilization/rupture. The resultant leakage of cathepsins is responsible for lysosomal cell death, which would be one of the causative factors of lifestyle-related diseases.
    Keywords:  ALDH2; Hsp70.1; LAMP2A; calpain–cathepsin hypothesis; chaperone-mediated autophagy; hydroxynonenal; lifestyle-related disease; lysosomal cell death
    DOI:  https://doi.org/10.3389/fmolb.2024.1378656
  37. Cell Biochem Funct. 2024 Jun;42(4): e4071
    Effects of metformin on cancers in experimental and clinical studies: Focusing on autophagy and AMPK/mTOR signaling pathways.
    Mohammad Yasin Zamanian, Maryam Golmohammadi, Alexey Yumashev, Ahmed Hjazi, Mariam Alaa Toama, Mervat Ahmed AbdRabou, Anita Gehlot, Enas R Alwaily, Niyousha Shirsalimi, Pankaj Kumar Yadav, Gervason Moriasi.
      Metformin (MET) is a preferred drug for the treatment of type 2 diabetes mellitus. Recent studies show that apart from its blood glucose-lowering effects, it also inhibits the development of various tumours, by inducing autophagy. Various studies have confirmed the inhibitory effects of MET on cancer cell lines' propagation, migration, and invasion. The objective of the study was to comprehensively review the potential of MET as an anticancer agent, particularly focusing on its ability to induce autophagy and inhibit the development and progression of various tumors. The study aimed to explore the inhibitory effects of MET on cancer cell proliferation, migration, and invasion, and its impact on key signaling pathways such as adenosine monophosphate-activated protein kinase (AMPK), mammalian target of rapamycin (mTOR), and PI3K. This review noted that MET exerts its anticancer effects by regulating key signalling pathways such as phosphoinositide 3-kinase (PI3K), LC3-I and LC3-II, Beclin-1, p53, and the autophagy-related gene (ATG), inhibiting the mTOR protein, downregulating the expression of p62/SQSTM1, and blockage of the cell cycle at the G0/G1. Moreover, MET can stimulate autophagy through pathways associated with the 5' AMPK, thereby inhibiting he development and progression of various human cancers, including hepatocellular carcinoma, prostate cancer, pancreatic cancer, osteosarcoma, myeloma, and non-small cell lung cancer. In summary, this detailed review provides a framework for further investigations that may appraise the autophagy-induced anticancer potential of MET and its repurposing for cancer treatment.
    Keywords:  AMPK; autophagy; autophagy markers; cancer; mTOR pathway; metformin
    DOI:  https://doi.org/10.1002/cbf.4071
  38. Biochim Biophys Acta Mol Basis Dis. 2024 Jun 09. pii: S0925-4439(24)00280-1. [Epub ahead of print] 167287
    Rapamycin promotes the intestinal barrier repair in ulcerative colitis via the mTOR/PBLD/AMOT signaling pathway.
    Yan Xu, Jinyuan Ou, Chuhong Zhang, Jiayue Chen, Junsheng Chen, Aimin Li, Bing Huang, Xinmei Zhao.
      Intestinal barrier dysfunction characterized by the functional loss of the intestinal epithelium's tight junction (TJ) barrier is a key factor in the pathogenesis of ulcerative colitis (UC). Although rapamycin, an mTOR (mechanistic target of rapamycin) inhibitor, has shown promise in inducing clinical remission and mucosal healing in inflammatory bowel disease, its underlying mechanism remains elusive. Thus, this study investigated the role of the mTOR pathway in regulating the intestinal barrier. To investigate the molecular mechanism regulating the intestinal barrier, specific intestinal epithelial phenazine biosynthesis-like domain-containing protein (PBLD)-deficient (PBLDIEC-/-) mice and control wild-type (WT) mice were intraperitoneally injected with rapamycin or MHY1485. To determine the relevance of the findings for UC, we analyzed transcriptome data and single-cell expression profiles from public databases and intestinal mucosal tissues obtained from patients with active UC or colon cancer. We observed that mTOR activation in the intestinal epithelium of patients with active UC. Moreover, in vivo, rapamycin markedly increased the expressions of PBLD and TJ proteins and reduced intestinal inflammation in mice with dextran sulfate sodium-induced enteritis. However, the therapeutic efficacy of rapamycin was notably reduced in PBLDIEC-/- mice. In vitro, rapamycin influenced PBLD expression by modulating the nuclear transcription of transcription factor EB (TFEB). Angiomotin (AMOT) could directly bind to PBLD, and rapamycin could not effectively increase the expression of TJ proteins after the knockdown of PBLD or AMOT. In summary, the administration of rapamycin is a potential treatment for UC, and targeting the mTOR/PBLD/AMOT axis is a potential novel approach for UC treatment.
    Keywords:  Intestinal barrier; Rapamycin; Tight junction; Ulcerative colitis; mTOR
    DOI:  https://doi.org/10.1016/j.bbadis.2024.167287
  39. Int Immunopharmacol. 2024 Jun 06. pii: S1567-5769(24)00858-0. [Epub ahead of print]136 112338
    LDHA contributes to nicotine induced cardiac fibrosis through autophagy flux impairment.
    Hui-Hui Wu, Jia-Min Du, Peng Liu, Fan-Liang Meng, Yue-Yan Li, Wen-Jing Li, Shuang-Xi Wang, Nai-Li Du, Yan Zheng, Liang Zhang, Hui-Yun Wang, Yi-Ran Liu, Chun-Hong Song, Xi Ni, Ying Li, Guo-Hai Su.
      Cardiac fibrosis is a typical feature of cardiac pathological remodeling, which is associated with adverse clinical outcomes and has no effective therapy. Nicotine is an important risk factor for cardiac fibrosis, yet its underlying molecular mechanism remains poorly understood. This study aimed to identify its potential molecular mechanism in nicotine-induced cardiac fibrosis. Our results showed nicotine exposure led to the proliferation and transformation of cardiac fibroblasts (CFs) into myofibroblasts (MFs) by impairing autophagy flux. Through the use of drug affinity responsive target stability (DARTS) assay, cellular thermal shift assay (CETSA), and surface plasmon resonance (SPR) technology, it was discovered that nicotine directly increased the stability and protein levels of lactate dehydrogenase A (LDHA) by binding to it. Nicotine treatment impaired autophagy flux by regulating the AMPK/mTOR signaling pathway, impeding the nuclear translocation of transcription factor EB (TFEB), and reducing the activity of cathepsin B (CTSB). In vivo, nicotine treatment exacerbated cardiac fibrosis induced in spontaneously hypertensive rats (SHR) and worsened cardiac function. Interestingly, the absence of LDHA reversed these effects both in vitro and in vivo. Our study identified LDHA as a novel nicotine-binding protein that plays a crucial role in mediating cardiac fibrosis by blocking autophagy flux. The findings suggest that LDHA could potentially serve as a promising target for the treatment of cardiac fibrosis.
    Keywords:  AMPK/mTOR/TFEB; Autophagy; Cardiac fibrosis; LDHA; Nicotine
    DOI:  https://doi.org/10.1016/j.intimp.2024.112338
  40. J Cell Biol. 2024 Sep 02. pii: e202310137. [Epub ahead of print]223(9):
    Signaling proteins in HSC fate determination are unequally segregated during asymmetric cell division.
    Amol Ugale, Dhanlakshmi Shunmugam, Lokesh G Pimpale, Elisabeth Rebhan, Manuela Baccarini.
      Hematopoietic stem cells (HSCs) continuously replenish mature blood cells with limited lifespans. To maintain the HSC compartment while ensuring output of differentiated cells, HSCs undergo asymmetric cell division (ACD), generating two daughter cells with different fates: one will proliferate and give rise to the differentiated cells' progeny, and one will return to quiescence to maintain the HSC compartment. A balance between MEK/ERK and mTORC1 pathways is needed to ensure HSC homeostasis. Here, we show that activation of these pathways is spatially segregated in premitotic HSCs and unequally inherited during ACD. A combination of genetic and chemical perturbations shows that an ERK-dependent mechanism determines the balance between pathways affecting polarity, proliferation, and metabolism, and thus determines the frequency of asymmetrically dividing HSCs. Our data identify druggable targets that modulate HSC fate determination at the level of asymmetric division.
    DOI:  https://doi.org/10.1083/jcb.202310137
  41. Biochem Biophys Res Commun. 2024 Jun 10. pii: S0006-291X(24)00784-8. [Epub ahead of print]725 150248
    Inhibition of CIRBP represses the proliferation and migration of vascular smooth muscle cells via inhibiting Rheb/mTORC1 axis.
    Jiaqi Zhao, Chenming Qiu, Rong Wan, Qiang Wang, Yan Zhang, Dachun Yang, Yongjian Yang, Xiongshan Sun.
      The excessive migration and proliferation of vascular smooth muscle cells (VSMCs) plays a vital role in vascular intimal hyperplasia. CIRBP is involved in the proliferation of various cancer cells. This study was aimed to explore the role of CIRBP in the proliferation and migration of VSMCs. Adenovirus was used to interfere with cold-inducible RNA-binding protein (CIRBP) expression, while lentivirus was used to overexpress Ras homolog enriched in brain (Rheb). Western blotting and qRT-PCR were used to evaluate the expression of CIRBP, Rheb, and mechanistic target of rapamycin complex 1 (mTORC1) activity. The cell proliferation was determined by Ki67 immunofluorescence staining and CCK-8 assay. The wound healing assay was performed to assess cell migration. Additionally, immunohistochemistry was conducted to explore the role of CIRBP in intimal hyperplasia after vascular injury. We found that silencing CIRBP inhibited the proliferation and migration of VSMCs, decreased the expression of Rheb and mTORC1 activity. Restoration of mTORC1 activity via insulin or overexpression of Rheb via lentiviral transfection both attenuated the inhibitory effects of silencing CIRBP on the proliferation and migration of VSMCs. Moreover, Rheb overexpression abolished the inhibitory effect of silencing CIRBP on mTORC1 activity in VSMCs. CIRBP was upregulated in the injured carotid artery. Silencing CIRBP ameliorated intimal hyperplasia after vascular injury. In the summary, silencing CIRBP attenuates mTORC1 activity via reducing Rheb expression, thereby supressing the proliferation and migration of VSMCs and intimal hyperplasia after vascular injury.
    Keywords:  CIRBP; Migration; Proliferation; Rheb; VSMCs; mTORC1
    DOI:  https://doi.org/10.1016/j.bbrc.2024.150248
  42. Front Pharmacol. 2024 ;15 1366061
    Pharmacological mTOR inhibitors in ameliorating Alzheimer's disease: current review and perspectives.
    Pei-Lun Xie, Meng-Yu Zheng, Ran Han, Wei-Xin Chen, Jin-Hua Mao.
      Traditionally, pharmacological mammalian/mechanistic targets of rapamycin (mTOR) kinase inhibitors have been used during transplantation and tumor treatment. Emerging pre-clinical evidence from the last decade displayed the surprising effectiveness of mTOR inhibitors in ameliorating Alzheimer's Disease (AD), a common neurodegenerative disorder characterized by progressive cognitive function decline and memory loss. Research shows mTOR activation as an early event in AD development, and inhibiting mTOR may promote the resolution of many hallmarks of Alzheimer's. Aberrant protein aggregation, including amyloid-beta (Aβ) deposition and tau filaments, and cognitive defects, are reversed upon mTOR inhibition. A closer inspection of the evidence highlighted a temporal dependence and a hallmark-specific nature of such beneficial effects. Time of administration relative to disease progression, and a maintenance of a functional lysosomal system, could modulate its effectiveness. Moreover, mTOR inhibition also exerts distinct effects between neurons, glial cells, and endothelial cells. Different pharmacological properties of the inhibitors also produce different effects based on different blood-brain barrier (BBB) entry capacities and mTOR inhibition sites. This questions the effectiveness of mTOR inhibition as a viable AD intervention strategy. In this review, we first summarize the different mTOR inhibitors available and their characteristics. We then comprehensively update and discuss the pre-clinical results of mTOR inhibition to resolve many of the hallmarks of AD. Key pathologies discussed include Aβ deposition, tauopathies, aberrant neuroinflammation, and neurovascular system breakdowns.
    Keywords:  Alzheimer’s disease; autophagy; mTOR; neuroinflammation; neurovascular system; rapamycin
    DOI:  https://doi.org/10.3389/fphar.2024.1366061
  43. Eur J Med Chem. 2024 Jun 10. pii: S0223-5234(24)00461-6. [Epub ahead of print]275 116581
    Discovery of autophagy-tethering compounds as potent NLRP3 degraders for IBD Immunotherapy.
    Kai Yin, Ziwen Zhang, Yanqing Mo, Hongyu Wu, Zhonglian Cao, Yongxing Xue, Mingrunlin Wang, Wei Guo, Li Feng, Chunchang Zhao, Xianfeng Gu.
      Nucleotide-binding oligomerization domain-like receptor pyrin domain containing 3 (NLRP3) constitutes an essential inflammasome sensor protein, pivotal in the orchestration of innate immunity. Given its paramount role, NLRP3 has recently emerged as an enticing therapeutic target for disorders associated with inflammation. In this study, we embarked on the design and synthesis of two series of compounds, endowed with the capacity to induce NLRP3 degradation via autophagy-tethering compounds (ATTECs)-an innovative targeted protein degradation technology. Notably, MC-ND-18 emerged as the most potent agent for effectuating NLRP3 degradation through autophagic mechanisms and concurrently exhibited marked anti-inflammatory efficacy in mice model of dextran sulfate sodium (DSS)-induced colitis. Consequently, we have successfully developed a pioneering NLRP3 protein degrader, offering a novel therapeutic avenue for ameliorating NLRP3-associated pathologies.
    DOI:  https://doi.org/10.1016/j.ejmech.2024.116581
  44. Neurobiol Dis. 2024 Jun 06. pii: S0969-9961(24)00155-4. [Epub ahead of print] 106556
    Atlastin-1 regulates endosomal tubulation and lysosomal proteolysis in human cortical neurons.
    Eliska Zlamalova, Catherine Rodger, Francesca Greco, Samuel R Cheers, Julia Kleniuk, Aishwarya G Nadadhur, Zuzana Kadlecova, Evan Reid.
      Mutation of the ATL1 gene is one of the most common causes of hereditary spastic paraplegia (HSP), a group of genetic neurodegenerative conditions characterised by distal axonal degeneration of the corticospinal tract axons. Atlastin-1, the protein encoded by ATL1, is one of three mammalian atlastins, which are homologous dynamin-like GTPases that control endoplasmic reticulum (ER) morphology by fusing tubules to form the three-way junctions that characterise ER networks. However, it is not clear whether atlastin-1 is required for correct ER morphology in human neurons and if so what the functional consequences of lack of atlastin-1 are. Using CRISPR-inhibition we generated human cortical neurons lacking atlastin-1. We demonstrate that ER morphology was altered in these neurons, with a reduced number of three-way junctions. Neurons lacking atlastin-1 had longer endosomal tubules, suggestive of defective tubule fission. This was accompanied by reduced lysosomal proteolytic capacity. As well as demonstrating that atlastin-1 is required for correct ER morphology in human neurons, our results indicate that lack of a classical ER-shaping protein such as atlastin-1 may cause altered endosomal tubulation and lysosomal proteolytic dysfunction. Furthermore, they strengthen the idea that defective lysosome function contributes to the pathogenesis of a broad group of HSPs, including those where the primary localisation of the protein involved is not at the endolysosomal system.
    Keywords:  Atlastin; Endoplasmic reticulum morphology; Endosomal traffic; Endosomal tubulation; Hereditary spastic paraplegia; Lysosomal proteolysis; Lysosome
    DOI:  https://doi.org/10.1016/j.nbd.2024.106556
  45. Blood Adv. 2024 Jun 11. pii: bloodadvances.2024012679. [Epub ahead of print]
    Mitoxantrone ameliorates ineffective erythropoiesis in a β-thalassemia intermedia mouse model.
    Haihang Zhang, Rui Liu, Zheng Fang, Ling Nie, Yanlin Ma, Fei Sun, Jingjing Mei, Zhiyin Song, Yelena Z Ginzburg, Jing Liu, Huiyong Chen.
      β-thalassemia is a condition characterized by reduced or absent synthesis of β-globin resulting from genetic mutations, leading to expanded and ineffective erythropoiesis. Mitoxantrone has been widely used clinically as an antitumor agent in light of its ability to inhibit cell proliferation. However, its therapeutic effect on expanded and ineffective erythropoiesis in β-thalassemia is untested. We found that mitoxantrone decreased α-globin precipitates and ameliorated anemia, splenomegaly and ineffective erythropoiesis in the HbbTh3/+ mouse model of β-thalassemia intermedia. The partially reversed ineffective erythropoiesis is a consequence of effects on autophagy as mitochondrial retention and protein levels of mTOR, P62 and LC3 in reticulocytes decreased in mitoxantrone-treated HbbTh3/+ mice. These data provide significant pre-clinical evidence for targeting autophagy as a novel therapeutic approach for β-thalassemia.
    DOI:  https://doi.org/10.1182/bloodadvances.2024012679
  46. Commun Biol. 2024 Jun 11. 7(1): 722
    Activation of the cell wall integrity pathway negatively regulates TORC2-Ypk1/2 signaling through blocking eisosome disassembly in Saccharomyces cerevisiae.
    Wataru Nomura, Yoshiharu Inoue.
      The target of rapamycin complex 2 (TORC2) signaling is associated with plasma membrane (PM) integrity. In Saccharomyces cerevisiae, TORC2-Ypk1/2 signaling controls sphingolipid biosynthesis, and Ypk1/2 phosphorylation by TORC2 under PM stress conditions is increased in a Slm1/2-dependent manner, under which Slm1 is known to be released from an eisosome, a furrow-like invagination PM structure. However, it remains unsolved how the activation machinery of TORC2-Ypk1/2 signaling is regulated. Here we show that edelfosine, a synthetic lysophospholipid analog, inhibits the activation of TORC2-Ypk1/2 signaling, and the cell wall integrity (CWI) pathway is involved in this inhibitory effect. The activation of CWI pathway blocked the eisosome disassembly promoted by PM stress and the release of Slm1 from eisosomes. Constitutive activation of TORC2-Ypk1/2 signaling exhibited increased sensitivity to cell wall stress. We propose that the CWI pathway negatively regulates the TORC2-Ypk1/2 signaling, which is involved in the regulatory mechanism to ensure the proper stress response to cell wall damage.
    DOI:  https://doi.org/10.1038/s42003-024-06411-2
  47. Acta Neuropathol. 2024 Jun 09. 147(1): 96
    The necroptosis cell death pathway drives neurodegeneration in Alzheimer's disease.
    Sriram Balusu, Bart De Strooper.
      Although apoptosis, pyroptosis, and ferroptosis have been implicated in AD, none fully explains the extensive neuronal loss observed in AD brains. Recent evidence shows that necroptosis is abundant in AD, that necroptosis is closely linked to the appearance of Tau pathology, and that necroptosis markers accumulate in granulovacuolar neurodegeneration vesicles (GVD). We review here the neuron-specific activation of the granulovacuolar mediated neuronal-necroptosis pathway, the potential AD-relevant triggers upstream of this pathway, and the interaction of the necrosome with the endo-lysosomal pathway, possibly providing links to Tau pathology. In addition, we underscore the therapeutic potential of inhibiting necroptosis in neurodegenerative diseases such as AD, as this presents a novel avenue for drug development targeting neuronal loss to preserve cognitive abilities. Such an approach seems particularly relevant when combined with amyloid-lowering drugs.
    DOI:  https://doi.org/10.1007/s00401-024-02747-5
  48. Oncoimmunology. 2024 ;13(1): 2364958
    Improving STING agonist-based cancer therapy by inhibiting the autophagy-related protein VPS34.
    Elisabetta Bartolini, Kris Van Moer, Bassam Janji.
      We have recently demonstrated that inhibiting VPS34 enhances T-cell-recruiting chemokines through the activation of the cGAS/STING pathway using the STING agonist ADU-S100. Combining VPS34 inhibitors with ADU-S100 increased cytokine release and improved tumor control in mouse models, suggesting a potential synergy between VPS34 inhibition and therapies based on STING agonists.
    Keywords:  Autophagy; CCL5; CD8 T cells; CXCL10; NK cells; PIK3C3; STING agonist; VPS34; immunotherapy; melanoma; renal cell carcinoma; type I IFN response
    DOI:  https://doi.org/10.1080/2162402X.2024.2364958
  49. Cell Mol Biol Lett. 2024 Jun 14. 29(1): 90
    ACE2 mediates tryptophan alleviation on diarrhea by repairing intestine barrier involved mTOR pathway.
    Jinze Li, Yingli Yan, Yang Fu, Zhe Chen, Yongjie Yang, Yu Li, Jie Pan, Feiwu Li, Cuifang Zha, Kai Miao, Lukuyu Ben, Muhammad Kashif Saleemi, Yongwen Zhu, Hui Ye, Lin Yang, Wence Wang.
      The membrane-delimited receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), angiotensin-converting enzyme 2 (ACE2), which is expressed in the intestine, collaborates with broad neutral amino acid transporter 1 (B0AT1). Tryptophan (Trp) is transported into intestinal epithelial cells by ACE2 and B0AT1. However, whether ACE2 and its binding protein B0AT1 are involved in Trp-mediated alleviation of intestinal injury is largely unknown. Here, we used weaned piglets and IPEC-J2 cells as models and found that ACE2/B0AT1 alleviated lipopolysaccharide (LPS)-induced diarrhea and promoted intestinal barrier recovery via transport of Trp. The levels of the aryl hydrocarbon receptor (AhR) and mechanistic target of rapamycin (mTOR) pathways were altered by ACE2. Dietary Trp supplementation in LPS-treated weaned piglets revealed that Trp alleviated diarrhea by promoting ACE2/B0AT1 expression, and examination of intestinal morphology revealed that the damage to the intestinal barrier was repaired. Our study demonstrated that ACE2 accompanied by B0AT1 mediated the alleviation of diarrhea by Trp through intestinal barrier repair via the mTOR pathway.
    Keywords:  ACE2; Aryl hydrocarbon receptor; B0AT1; Tryptophan; mTOR
    DOI:  https://doi.org/10.1186/s11658-024-00603-8
  50. Biochim Biophys Acta Mol Basis Dis. 2024 Jun 09. pii: S0925-4439(24)00281-3. [Epub ahead of print]1870(7): 167288
    Effect of alternating nicotinamide phosphoribosyltransferase expression levels on mitophagy in Alzheimer's disease mouse models.
    Na Zhao, Bo Xu, Jie Xia, Jing Wang, Xianliang Zhang, Qingwei Yan.
      AD is the abbreviation for Alzheimer's Disease, which is a neurodegenerative disorder that features progressive dysfunction in cognition. Previous research has reported that mitophagy impairment and mitochondrial dysfunction have been crucial factors in the AD's pathogenesis. More recently, literature has emerged which offers findings suggesting that the nicotinamide adenine dinucleotide (short for NAD+) augmentation eliminates the defective mitochondria and restores mitophagy. Meanwhile, as an enzyme which is rate-limiting, the Nicotinamide phosphoribosyltransferase, or NAMPT, is part of the salvage pathway of NAD+ synthesis. Therefore, the aim of the research project has been to produce proof for how the NAMPT-NAD +-silent information-regulated transcription factors1/3 (short for SIRT1/3) axis function in mediating mitophagy in APP/PS1 mice aged six months. The results revealed that the NAMPT-NAD+-SIRT1/3 axis in the APP/PS1 mice's hippocampus was considerably declined. Surprisingly, P7C3 (an NAMPT activator) noticeably promoted the NAD+-SIRT1/3 axis, improved mitochondrial structure and function, enhanced mitophagy activity along with the ability of learning and memory. While FK866 (an NAMPT inhibitor) reversed the decreased NAD+-SIRT1/3 axis, and even exacerbated Aβ plaque deposition level in the APP/PS1 mice's hippocampus. The findings observed in this study indicate two main points: avoiding downregulation of the NAMPT activity can prevent AD-related mitophagy impairment; on the other hand, NAMPT characterizes a potential therapeutic intervention regarding AD pathogenesis.
    Keywords:  Alzheimer's disease; FK866; Mitophagy; NAMPT; P7C3
    DOI:  https://doi.org/10.1016/j.bbadis.2024.167288
  51. Sci Rep. 2024 06 13. 14(1): 13655
    SS-31 treatment ameliorates cardiac mitochondrial morphology and defective mitophagy in a murine model of Barth syndrome.
    Silvia Russo, Domenico De Rasmo, Roberta Rossi, Anna Signorile, Simona Lobasso.
      Barth syndrome (BTHS) is a lethal rare genetic disorder, which results in cardiac dysfunction, severe skeletal muscle weakness, immune issues and growth delay. Mutations in the TAFAZZIN gene, which is responsible for the remodeling of the phospholipid cardiolipin (CL), lead to abnormalities in mitochondrial membrane, including alteration of mature CL acyl composition and the presence of monolysocardiolipin (MLCL). The dramatic increase in the MLCL/CL ratio is the hallmark of patients with BTHS, which is associated with mitochondrial bioenergetics dysfunction and altered membrane ultrastructure. There are currently no specific therapies for BTHS. Here, we showed that cardiac mitochondria isolated from TAFAZZIN knockdown (TazKD) mice presented abnormal ultrastructural membrane morphology, accumulation of vacuoles, pro-fission conditions and defective mitophagy. Interestingly, we found that in vivo treatment of TazKD mice with a CL-targeted small peptide (named SS-31) was able to restore mitochondrial morphology in tafazzin-deficient heart by affecting specific proteins involved in dynamic process and mitophagy. This agrees with our previous data showing an improvement in mitochondrial respiratory efficiency associated with increased supercomplex organization in TazKD mice under the same pharmacological treatment. Taken together our findings confirm the beneficial effect of SS-31 in the amelioration of tafazzin-deficient dysfunctional mitochondria in a BTHS animal model.
    DOI:  https://doi.org/10.1038/s41598-024-64368-y
  52. Cell Mol Life Sci. 2024 Jun 10. 81(1): 254
    Pyruvate kinase M2 sustains cardiac mitochondrial quality surveillance in septic cardiomyopathy by regulating prohibitin 2 abundance via S91 phosphorylation.
    Yingzhen Du, Jialei Li, Zhe Dai, Yuxin Chen, Yao Zhao, Xiaoman Liu, Tian Xia, Pingjun Zhu, Yijin Wang.
      The endogenous mitochondrial quality control (MQC) system serves to protect mitochondria against cellular stressors. Although mitochondrial dysfunction contributes to cardiac damage during many pathological conditions, the regulatory signals influencing MQC disruption during septic cardiomyopathy (SC) remain unclear. This study aimed to investigate the involvement of pyruvate kinase M2 (PKM2) and prohibitin 2 (PHB2) interaction followed by MQC impairment in the pathogenesis of SC. We utilized LPS-induced SC models in PKM2 transgenic (PKM2TG) mice, PHB2S91D-knockin mice, and PKM2-overexpressing HL-1 cardiomyocytes. After LPS-induced SC, cardiac PKM2 expression was significantly downregulated in wild-type mice, whereas PKM2 overexpression in vivo sustained heart function, suppressed myocardial inflammation, and attenuated cardiomyocyte death. PKM2 overexpression relieved sepsis-related mitochondrial damage via MQC normalization, evidenced by balanced mitochondrial fission/fusion, activated mitophagy, restored mitochondrial biogenesis, and inhibited mitochondrial unfolded protein response. Docking simulations, co-IP, and domain deletion mutant protein transfection experiments showed that PKM2 phosphorylates PHB2 at Ser91, preventing LPS-mediated PHB2 degradation. Additionally, the A domain of PKM2 and the PHB domain of PHB2 are required for PKM2-PHB2 binding and PHB2 phosphorylation. After LPS exposure, expression of a phosphorylation-defective PHB2S91A mutant negated the protective effects of PKM2 overexpression. Moreover, knockin mice expressing a phosphorylation-mimetic PHB2S91D mutant showed improved heart function, reduced inflammation, and preserved mitochondrial function following sepsis induction. Abundant PKM2 expression is a prerequisite to sustain PKM2-PHB2 interaction which is a key element for preservation of PHB2 phosphorylation and MQC, presenting novel interventive targets for the treatment of septic cardiomyopathy.
    Keywords:  MQC; Mitochondria; PHB2; PKM2; Septic cardiomyopathy
    DOI:  https://doi.org/10.1007/s00018-024-05253-9
  53. MedComm (2020). 2024 Jun;5(6): e566
    Myricanol prevents aging-related sarcopenia by rescuing mitochondrial dysfunction via targeting peroxiredoxin 5.
    Shengnan Shen, Qiwen Liao, Peng Lyu, Jigang Wang, Ligen Lin.
      Aging is a process that represents the accumulation of changes in organism overtime. In biological level, accumulations of molecular and cellular damage in aging lead to an increasing risk of diseases like sarcopenia. Sarcopenia reduces mobility, leads to fall-related injuries, and diminishes life quality. Thus, it is meaningful to find out novel therapeutic strategies for sarcopenia intervention that may help the elderly maintain their functional ability. Oxidative damage-induced dysfunctional mitochondria are considered as a culprit of muscle wasting during aging. Herein, we aimed to demonstrate whether myricanol (MY) protects aged mice against muscle wasting through alleviating oxidative damage in mitochondria and identify the direct protein target and its underlying mechanism. We discovered that MY protects aged mice against the loss of muscle mass and strength through scavenging reactive oxygen species accumulation to rebuild the redox homeostasis. Taking advantage of biophysical assays, peroxiredoxin 5 was discovered and validated as the direct target of MY. Through activating peroxiredoxin 5, MY reduced reactive oxygen species accumulation and damaged mitochondrial DNA in C2C12 myotubes. Our findings provide an insight for therapy against sarcopenia through alleviating oxidative damage-induced dysfunctional mitochondria by targeting peroxiredoxin 5, which may contribute an insight for healthy aging.
    Keywords:  healthy aging; mitochondria; myricanol; peroxiredoxin 5; redox homeostasis; sarcopenia
    DOI:  https://doi.org/10.1002/mco2.566
  54. Front Cell Neurosci. 2024 ;18 1381279
    Transforming growth factor-β1 protects mechanically injured cortical murine neurons by reducing trauma-induced autophagy and apoptosis.
    Yanlei Li, Huixiong Deng, Hengyao Zhang, Lin Yang, Shenmiao Wang, Haoyang Wang, Jiacheng Zhu, Xiaoning Li, Xiaoxuan Chen, Yinhong Lin, Rui Li, Gefei Wang, Kangsheng Li.
      Transforming growth factor β1 (TGF-β1) has a neuroprotective function in traumatic brain injury (TBI) through its anti-inflammatory and immunomodulatory properties. However, the precise mechanisms underlying the neuroprotective actions of TGF-β1 on the cortex require further investigation. In this study, we were aimed to investigate the regulatory function of TGF-β1 on neuronal autophagy and apoptosis using an in vitro primary cortical neuron trauma-injury model. LDH activity was assayed to measure cell viability, and intracellular [Ca2+] was measured using Fluo-4-AM in an in vitro primary cortical neuron trauma-injury model. RNA-sequencing (RNAseq), immunofluorescent staining, transmission electron microscopy (TEM), western blot and CTSD activity detection were employed. We observed significant enrichment of DEGs related to autophagy, apoptosis, and the lysosome pathway in trauma-injured cortical neurons. TEM confirmed the presence of autophagosomes as well as autophagolysosomes. Western blot revealed upregulation of autophagy-related protein light chain 3 (LC3-II/LC3-I), sequestosome 1 (SQSTM1/p62), along with apoptosis-related protein cleaved-caspase 3 in trauma-injured primary cortical neurons. Furthermore, trauma-injured cortical neurons showed an upregulation of lysosomal marker protein (LAMP1) and lysosomal enzyme mature cathepsin D (mCTSD), but a decrease in the activity of CTSD enzyme. These results indicated that apoptosis was up-regulated in trauma- injured cortical neurons at 24 h, accompanied by lysosomal dysfunction and impaired autophagic flux. Notably, TGF-β1 significantly reversed these changes. Our results suggested that TGF-β1 exerted neuroprotective effects on trauma- injured cortical neurons by reducing lysosomal dysfunction, decreasing the accumulation of autophagosomes and autophagolysosomes, and enhancing autophagic flux.
    Keywords:  apoptosis; autophagy; cortical neurons; lysosomal; transforming growth factor-β1; trauma-injured
    DOI:  https://doi.org/10.3389/fncel.2024.1381279
  55. Cell Host Microbe. 2024 Jun 12. pii: S1931-3128(24)00132-X. [Epub ahead of print]32(6): 913-924.e7
    Bacterial esterases reverse lipopolysaccharide ubiquitylation to block host immunity.
    Magdalena Szczesna, Yizhou Huang, Rachel E Lacoursiere, Francesca Bonini, Vito Pol, Fulya Koc, Beatrice Ward, Paul P Geurink, Jonathan N Pruneda, Teresa L M Thurston.
      Aspects of how Burkholderia escape the host's intrinsic immune response to replicate in the cell cytosol remain enigmatic. Here, we show that Burkholderia has evolved two mechanisms to block the activity of Ring finger protein 213 (RNF213)-mediated non-canonical ubiquitylation of bacterial lipopolysaccharide (LPS), thereby preventing the initiation of antibacterial autophagy. First, Burkholderia's polysaccharide capsule blocks RNF213 association with bacteria and second, the Burkholderia deubiquitylase (DUB), TssM, directly reverses the activity of RNF213 through a previously unrecognized esterase activity. Structural analysis provides insight into the molecular basis of TssM esterase activity, allowing it to be uncoupled from its isopeptidase function. Furthermore, a putative TssM homolog also displays esterase activity and removes ubiquitin from LPS, establishing this as a virulence mechanism. Of note, we also find that additional immune-evasion mechanisms exist, revealing that overcoming this arm of the host's immune response is critical to the pathogen.
    Keywords:  Autophagy; Burkholderia; RNF213; TssM; Ubiquitin esterase; bacterial effector; cell-autonomous immunity; non-canonical ubiquitylation
    DOI:  https://doi.org/10.1016/j.chom.2024.04.012
  56. Annu Rev Genet. 2024 Jun 10.
    Regulatory Mechanisms of Aging Through the Nutritional and Metabolic Control of Amino Acid Signaling in Model Organisms.
    Fumiaki Obata, Masayuki Miura.
      Life activities are supported by the intricate metabolic network that is fueled by nutrients. Nutritional and genetic studies in model organisms have determined that dietary restriction and certain mutations in the insulin signaling pathway lead to lifespan extension. Subsequently, the detailed mechanisms of aging as well as various nutrient signaling pathways and their relationships have been investigated in a wide range of organisms, from yeast to mammals. This review summarizes the roles of nutritional and metabolic signaling in aging and lifespan with a focus on amino acids, the building blocks of organisms. We discuss how lifespan is affected by the sensing, transduction, and metabolism of specific amino acids and consider the influences of life stage, sex, and genetic background on the nutritional control of aging. Our goal is to enhance our understanding of how nutrients affect aging and thus contribute to the biology of aging and lifespan.
    DOI:  https://doi.org/10.1146/annurev-genet-111523-102042
  57. Cell Death Dis. 2024 Jun 12. 15(6): 410
    Human gastric cancer progression and stabilization of ATG2B through RNF5 binding facilitated by autophagy-associated CircDHX8.
    Guanxin Wei, Xiang Chen, Tuo Ruan, Xianxiong Ma, Xiuxian Zhu, Wenhao Wen, Danzeng He, Kaixiong Tao, Chuanqing Wu.
      The role of circDHX8 in the interplay between autophagy and gastric cancer (GC) progression remains unclear. In this study, we investigated the mechanism underlying the role of hsa_circ_003899 (circDHX8) in the malignancy of GC. Differential expression of circRNAs between GC and normal tissues was determined using circle-seq and microarray datasets (GSE83521). These circRNAs were validated using qPCR and Sanger sequencing. The function of circDHX8 was investigated through interference with circDHX8 expression experiments using in vitro and in vivo functional assays. Western blotting, immunofluorescence, and transmission electron microscopy were used to establish whether circDHX8 promoted autophagy in GC cells. To elucidate the mechanism underlying the circDHX8-mediated regulation of autophagy, we performed bioinformatics analysis, RNA pull-down, mass spectrometry (MS), RNA immunoprecipitation (RIP), and other western Blot related experiments. Hsa_circ_0003899 (circDHX8) was identified as upregulated and shown to enhance the malignant progression in GC cells by promoting cellular autophagy. Mechanistically, circDHX8 increased ATG2B protein levels by preventing ubiquitin-mediated degradation, thereby facilitating cell proliferation and invasion in GC. Additionally, circDHX8 directly interacts with the E3 ubiquitin-protein ligase RNF5, inhibiting the RNF5-mediated degradation of ATG2B. Concurrently, ATG2B, an acetylated protein, is subjected to SIRT1-mediated deacetylation, enhancing its binding to RNF5. Consequently, we established a novel mechanism for the role of circDHX8 in the malignant progression of GC.
    DOI:  https://doi.org/10.1038/s41419-024-06782-8
  58. bioRxiv. 2024 May 30. pii: 2024.05.28.596287. [Epub ahead of print]
    FICD deficiency protects mice from hypertrophy-induced heart failure via BiP-mediated activation of the UPR ER and ER-phagy.
    Shannon M Lacy, Rebecca J Taubitz, Nicholas D Urban, Samantha N Turowski, Eric D Smith, Adam S Helms, Daniel E Michele, Matthias C Truttmann.
      Cardiomyocytes require the HSP70 chaperone BiP to maintain proteostasis in the endoplasmic reticulum (ER) following cardiac stress. The adenylyl transferase (AMPylase) FICD is increasingly recognized to regulate BiP activity through the post-translational addition of an adenosine monophosphate moiety to BiP surface residues. However, the physiological impact of FICD-mediated BiP regulation in the context of cardiovascular health is unknown. Here, we find that FICD deficiency prevents pressure overload-associated heart failure, hypertrophy, and fibrosis, and that FICD knockout mice maintain normal cardiac function after cardiac pressure overload. At a cellular level, we observe that FICD-mediated BiP AMPylation blunts the induction of the unfolded protein response (UPR ER ) and impairs BiP interaction with FAM134B, an ER-phagy receptor, thus limiting ER-phagy induction under stress. In contrast, FICD loss significantly increases BiP-dependent UPR ER induction and ER-phagy in stressed cardiomyocytes. We also uncover cell type-specific consequences of FICD activity in response to ER stress, positioning FICD as a critical proteostasis regulator in cardiac tissue. Our results highlight a novel regulatory paradigm controlling stress resilience in cardiomyocytes and offer a rationale to consider FICD as a therapeutic target to treat cardiac hypertrophy.
    DOI:  https://doi.org/10.1101/2024.05.28.596287
  59. Eur J Pharmacol. 2024 Jun 07. pii: S0014-2999(24)00403-5. [Epub ahead of print] 176715
    Acteoside delays the fibrosis process of diabetic nephropathy by anti-oxidation and regulating the autophagy-lysosome pathway.
    Mengqi Zhou, Shujiao Zhang, Xuehui Bai, Yuzi Cai, Zeyu Zhang, Pingna Zhang, Chengyuan Xue, Huijuan Zheng, Quanmei Sun, Dong Han, Lixia Lou, Yaoxian Wang, Weijing Liu.
      Renal fibrosis is the final pathological change of kidney disease, it has also been recognized to be critical for the final progression of diabetic nephropathy (DN) to kidney failure. Acteoside (ACT) is a phenylethanoid glycoside widely distributed in dicotyledonous plants. It has many pharmacological activities, such as anti-oxidation, anti-inflammation, anti-cancer, neuroprotection, cardiovascular protection, anti-diabetes, bone and cartilage protection, liver and kidney protection, and antibacterial activity. This study aims to investigate the protective effects of ACT on renal interstitial fibrosis in rats with DN induced by intraperitoneal injection of streptozocin (STZ) combined with unilateral nephrectomy and its mechanism. In vivo and in vitro, the effects of ACT on reactive oxygen species (ROS) level, oxidative tubular injury, as well as damage of autophagic flux and lysosome in the DN model were detected. Results indicate that administration of ACT delayed the progression of renal interstitial fibrosis in DN by anti-oxidation and regulating the autophagy-lysosome pathway, which may potentially be attributed to the regulatory influence of ACT on transcription factor EB (TFEB).
    Keywords:  Acteoside; Autophagy; Diabetic nephropathy; Lysosomes; Oxidative stress
    DOI:  https://doi.org/10.1016/j.ejphar.2024.176715
  60. Mol Neurobiol. 2024 Jun 12.
    20-Deoxyingenol Activates Mitophagy Through TFEB and Promotes Functional Recovery After Spinal Cord Injury.
    Chenyu Wu, Yu Chen, Ximiao Chen, Yekai Zhang, Xiaoying Zhao, Yuxin Deng, Chenchao Li, Di Zhang, Xiaolei Zhang, Sheng Wang.
      Spinal cord injury (SCI) can lead to permanent paralysis and various motor, sensory and autonomic nervous system dysfunction. The complex pathophysiological processes limit the effectiveness of many clinical treatments. Mitochondria has been reported to play a key role in the pathogenesis of SCI; while mitophagy is a protective mechanism against mitochondrial dysfunction. However, there is recently little drugs that may targeted activate mitophagy to treat SCI. In this study, we evaluated the role of 20-Deoxyingenol (20-DOI) in SCI and explored its potential mechanisms. We used a SCI rat model and evaluated the functional outcomes after the injury. Western blotting and immunofluorescence techniques were used to analyze the levels of mitophagy, apoptosis, and TFEB-related signaling pathways. Our research results show that 20-DOI significantly improves the apoptosis of neural cells after TBHP stimulation and functional recovery after spinal cord injury. In addition, mitophagy, TFEB levels, and apoptosis are related to the mechanism of 20-DOI treatment for spinal cord injury. Specifically, our research results indicate that 20-DOI restored the autophagic flux after injury, thereby inducing mitophagy, eliminating the accumulation of Cyto C, and inhibiting apoptosis. Further mechanism research suggests that 20-DOI may regulate mitophagy by promoting TFEB nuclear translocation. These results indicate that 20-DOI can significantly promote recovery after spinal cord injury, which may be a promising treatment method for spinal cord injury.
    Keywords:  20-Deoxyingenol; Apoptosis; Autophagy; Mitophagy; Spinal cord injury; TFEB
    DOI:  https://doi.org/10.1007/s12035-024-04283-5
  61. Nat Commun. 2024 Jun 11. 15(1): 4988
    Immunological synapse formation between T regulatory cells and cancer-associated fibroblasts promotes tumour development.
    Athina Varveri, Miranta Papadopoulou, Zacharias Papadovasilakis, Ewoud B Compeer, Aigli-Ioanna Legaki, Anastasios Delis, Vasileia Damaskou, Louis Boon, Sevasti Papadogiorgaki, Martina Samiotaki, Periklis G Foukas, Aristides G Eliopoulos, Aikaterini Hatzioannou, Themis Alissafi, Michael L Dustin, Panayotis Verginis.
      Cancer-associated fibroblasts (CAFs) have emerged as a dominant non-hematopoietic cell population in the tumour microenvironment, serving diverse functions in tumour progression. However, the mechanisms via which CAFs influence the anti-tumour immunity remain poorly understood. Here, using multiple tumour models and biopsies from cancer patients, we report that α-SMA+ CAFs can form immunological synapses with Foxp3+ regulatory T cells (Tregs) in tumours. Notably, α-SMA+ CAFs can phagocytose and process tumour antigens and exhibit a tolerogenic phenotype which instructs movement arrest, activation and proliferation in Tregs in an antigen-specific manner. Moreover, α-SMA+ CAFs display double-membrane structures resembling autophagosomes in their cytoplasm. Single-cell transcriptomic data showed an enrichment in autophagy and antigen processing/presentation pathways in α-SMA-expressing CAF clusters. Conditional knockout of Atg5 in α-SMA+ CAFs promoted inflammatory re-programming in CAFs, reduced Treg cell infiltration and attenuated tumour development. Overall, our findings reveal an immunosuppressive mechanism entailing the formation of synapses between α-SMA+ CAFs and Tregs in an autophagy-dependent manner.
    DOI:  https://doi.org/10.1038/s41467-024-49282-1
  62. Res Sq. 2024 May 30. pii: rs.3.rs-4431604. [Epub ahead of print]
    Pink1/Parkin deficiency alters circulating lymphocyte populations and increases platelet-T cell aggregates in rats.
    Jane E Manganaro, Katy Emanuel, Benjamin G Lamberty, Joseph W George, Kelly L Stauch.
      Parkinson's disease (PD) is the most common progressive neurodegenerative movement disorder and results from the selective loss of dopaminergic neurons in the substantia nigra pars compacta. Pink1 and Parkin are proteins that function together in mitochondrial quality control, and when they carry loss-of-function mutations lead to familial forms of PD. While much research has focused on central nervous system alterations in PD, peripheral contributions to PD pathogenesis are increasingly appreciated. We report Pink1/Parkin regulate glycolytic and mitochondrial oxidative metabolism in peripheral blood mononuclear cells (PBMCs) from rats. Pink1/Parkin deficiency induces changes in the circulating lymphocyte populations, namely increased CD4 + T cells and decreased CD8 + T cells and B cells. Loss of Pink1/Parkin leads to elevated platelet counts in the blood and increased platelet-T cell aggregation. Platelet-lymphocyte aggregates are associated with increased thrombosis risk, and venous thrombosis is a cause of sudden death in PD, suggesting targeting the Pink1/Parkin pathway in the periphery has therapeutic potential.
    DOI:  https://doi.org/10.21203/rs.3.rs-4431604/v1
  63. Int J Biol Macromol. 2024 Jun 06. pii: S0141-8130(24)03701-2. [Epub ahead of print] 132896
    Fibroblast growth factor 21 alleviates idiopathic pulmonary fibrosis by inhibiting PI3K-AKT-mTOR signaling and stimulating autophagy.
    Jianying Qi, Yuanyuan Wu, Zhimou Guo, Shenglong Zhu, Jingjing Xiong, Fei Hu, Xinmiao Liang, Xianlong Ye.
      Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive pulmonary disease with an unclear pathogenesis and no available specific drug treatment. The principal etiological factors are lung inflammation caused by environmental factors, damage to alveolar epithelial cells, leading to epithelial-mesenchymal transition (EMT), and the abnormal proliferation of fibroblasts. Here, we have demonstrated that fibroblast growth factor 21 (FGF21) ameliorates IPF via the autophagy pathway. We administered FGF21 to bleomycin (BLM)-treated mice, which ameliorated their defects in lung function, reduced the accumulation of collagen, restored tissue structure, reduced the deposition of hydroxyproline, reduced the expression of collagen I and α-SMA and increased the expression of E-cadherin. The expression of LC3BII and the number of autophagosomes were significantly higher in the lungs. The expression of AKT and mTOR was significantly reduced by FGF21 treatment. We also determined the effects of FGF21 in A549 cells treated with TGF-β, and found that FGF21 significantly inhibits activation of the AKT signaling pathway, thereby reducing TGF-β-induced EMT and preventing the uncontrolled proliferation of fibroblasts. We conclude that FGF21 ameliorates IPF by inhibiting the PI3K-AKT-mTOR signaling pathway and activating autophagy, which provides a theoretical basis for FGF21 to be used for the treatment of IPF.
    Keywords:  Autophagy; EMT; FGF21; Idiopathic pulmonary fibrosis; PI3K-AKT-mTOR signaling pathway
    DOI:  https://doi.org/10.1016/j.ijbiomac.2024.132896
  64. Biochim Biophys Acta Mol Basis Dis. 2024 Jun 11. pii: S0925-4439(24)00282-5. [Epub ahead of print] 167289
    Autophagy unveiled: New horizons in health and disease.
    Pooneh Mokarram, Saeid Ghavami.
      
    DOI:  https://doi.org/10.1016/j.bbadis.2024.167289
  65. bioRxiv. 2024 Jun 01. pii: 2024.05.31.596474. [Epub ahead of print]
    Loss of the lysosomal protein CLN3 modifies the lipid content of the nuclear envelope leading to DNA damage and activation of YAP1 pro-apoptotic signaling.
    Neuza Domingues, Alessia Calcagni', Joana Pires, Sofia Roque Freire, Niculin Joachim Herz, Tuong Huynh, Katarzyna Wieciorek, Maria João Moreno, Tiago Fleming Outeiro, Henrique Girão, Ira Milosevic, Andrea Ballabio, Nuno Raimundo.
      Batten disease is characterized by early-onset blindness, juvenile dementia and death during the second decade of life. The most common genetic causes are mutations in the CLN3 gene encoding a lysosomal protein. There are currently no therapies targeting the progression of the disease, mostly due to the lack of knowledge about the disease mechanisms. To gain insight into the impact of CLN3 loss on cellular signaling and organelle function, we generated CLN3 knock-out cells in a human cell line (CLN3-KO), and performed RNA sequencing to obtain the cellular transcriptome. Following a multi-dimensional transcriptome analysis, we identified the transcriptional regulator YAP1 as a major driver of the transcriptional changes observed in CLN3-KO cells. We further observed that YAP1 pro-apoptotic signaling is hyperactive as a consequence of CLN3 functional loss in retinal pigment epithelia cells, and in the hippocampus and thalamus of CLN3 exΔ7/8 mice, an established model of Batten disease. Loss of CLN3 activates YAP1 by a cascade of events that starts with the inability of releasing glycerophosphodiesthers from CLN3-KO lysosomes, which leads to perturbations in the lipid content of the nuclear envelope and nuclear dysmorphism. This results in increased number of DNA lesions, activating the kinase c-Abl, which phosphorylates YAP1, stimulating its pro-apoptotic signaling. Altogether, our results highlight a novel organelle crosstalk paradigm in which lysosomal metabolites regulate nuclear envelope content, nuclear shape and DNA homeostasis. This novel molecular mechanism underlying the loss of CLN3 in mammalian cells and tissues may open new c-Abl-centric therapeutic strategies to target Batten disease.
    DOI:  https://doi.org/10.1101/2024.05.31.596474
  66. Life Sci. 2024 Jun 07. pii: S0024-3205(24)00388-6. [Epub ahead of print] 122798
    Tricetin protects against liver fibrosis through promoting autophagy and Nrf2 signaling in hepatic stellate cells.
    Wanzhi Li, Ruyue Lv, Tangbin Zou, Ming Chen.
       AIMS: The study aims to investigate the role and underlying mechanisms of tricetin in regulating hepatic stellate cells (HSCs) activation.
    MAIN METHODS: We treated human hepatic stellate cells line LX-2 and freshly isolated primary mouse hepatic stellate cells (mHSCs) with tricetin, pharmacological inhibitors and siRNA. Western blot, immunofluorescence, quantitative PCR were used to evaluate the expression of fibrotic markers, autophagy levels and Nrf2 (nuclear factor E2-related factor 2) signaling.
    KEY FINDINGS: Herein, we demonstrated that tricetin strongly attenuated the proliferation, migration, lipid droplets (LDs) loss and fibrotic markers Col 1a1 (type I α 1 collagen) and α-SMA (α-smooth muscle actin) expression in LX-2 cells. Moreover, tricetin time- and dose-dependently provoked autophagic formation in LX-2 cells. Autophagy inhibition by pharmacological intervention or genetic ATG5 (autophagy related 5) silencing facilitated tricetin-induced downregulation of profibrotic markers in LX-2 cells. Additionally, tricetin treatment reduced reactive oxygen species (ROS) accumulation, promoted Nrf2 signaling in LX-2 cells and pretreatment with ROS scavenger NAC partially reversed tricetin-induced autophagy and enhanced tricetin-mediated HSCs inactivation. Nrf2 silencing partially reversed tricetin-mediated inhibition of α-SMA expression. Finally, utilizing primary mouse hepatic stellate cells (mHSCs), we demonstrated that tricetin also induced autophagy activation, repressed TGF-β1-induced LDs loss and fibrotic marker expression and pretreatment with CQ further sensitized these effects.
    SIGNIFICANCE: Our study indicates that tricetin's actions may represent an effective strategy to treat liver fibrosis and help identify novel therapeutic targets, especially in combination with autophagy inhibitors.
    Keywords:  Autophagy; Hepatic stellate cell activation; Nrf2; ROS; Tricetin
    DOI:  https://doi.org/10.1016/j.lfs.2024.122798
  67. Cell Rep. 2024 Jun 07. pii: S2211-1247(24)00664-8. [Epub ahead of print]43(6): 114336
    Reproductive regulation of the mitochondrial stress response in Caenorhabditis elegans.
    Nikolaos Charmpilas, Aggeliki Sotiriou, Konstantinos Axarlis, Nektarios Tavernarakis, Thorsten Hoppe.
      Proteome integrity is fundamental for cellular and organismal homeostasis. The mitochondrial unfolded protein response (UPRmt), a key component of the proteostasis network, is activated in a non-cell-autonomous manner in response to mitochondrial stress in distal tissues. However, the importance of inter-tissue communication for UPRmt inducibility under physiological conditions remains elusive. Here, we show that an intact germline is essential for robust UPRmt induction in the Caenorhabditis elegans somatic tissues. A series of nematode mutants with germline defects are unable to respond to genetic or chemical UPRmt inducers. Our genetic analysis suggests that reproductive signals, rather than germline stem cells, are responsible for somatic UPRmt induction. Consistent with this observation, we show that UPRmt is sexually dimorphic, as male nematodes are inherently unresponsive to mitochondrial stress. Our findings highlight a paradigm of germline-somatic communication and suggest that reproductive cessation is a primary cause of age-related UPRmt decline.
    Keywords:  C. elegans; CP: Developmental biology; CP: Molecular biology; aging; germline; mitochondria; proteostasis; unfolded protein response
    DOI:  https://doi.org/10.1016/j.celrep.2024.114336
  68. Proc Natl Acad Sci U S A. 2024 Jun 18. 121(25): e2310793121
    Unconventional mechanism of action and resistance to rapalogs in renal cancer.
    Juan Yang, Ramesh Butti, Shannon Cohn, Vanina Toffessi-Tcheuyap, Arijit Mal, Mylinh Nguyen, Christina Stevens, Alana Christie, Akhilesh Mishra, Yuanqing Ma, Jiwoong Kim, Robert Abraham, Payal Kapur, Robert E Hammer, James Brugarolas.
      mTORC1 is aberrantly activated in renal cell carcinoma (RCC) and is targeted by rapalogs. As for other targeted therapies, rapalogs clinical utility is limited by the development of resistance. Resistance often results from target mutation, but mTOR mutations are rarely found in RCC. As in humans, prolonged rapalog treatment of RCC tumorgrafts (TGs) led to resistance. Unexpectedly, explants from resistant tumors became sensitive both in culture and in subsequent transplants in mice. Notably, resistance developed despite persistent mTORC1 inhibition in tumor cells. In contrast, mTORC1 became reactivated in the tumor microenvironment (TME). To test the role of the TME, we engineered immunocompromised recipient mice with a resistance mTOR mutation (S2035T). Interestingly, TGs became resistant to rapalogs in mTORS2035T mice. Resistance occurred despite mTORC1 inhibition in tumor cells and could be induced by coculturing tumor cells with mutant fibroblasts. Thus, enforced mTORC1 activation in the TME is sufficient to confer resistance to rapalogs. These studies highlight the importance of mTORC1 inhibition in nontumor cells for rapalog antitumor activity and provide an explanation for the lack of mTOR resistance mutations in RCC patients.
    Keywords:  Cancer-associated fibroblasts (CAFs); everolimus; kinase inhibitors; patient-derived xenograft (PDX); temsirolimus
    DOI:  https://doi.org/10.1073/pnas.2310793121
  69. STAR Protoc. 2024 Jun 07. pii: S2666-1667(24)00286-7. [Epub ahead of print]5(2): 103121
    Protocol for qualitative analysis of lysosome immunoprecipitation from patient-derived glioblastoma stem-like cells.
    Clément Maghe, Julie Gavard.
      Lysosomes are critical for the sustenance of glioblastoma stem-like cells (GSCs) properties. We present a protocol to enrich and purify lysosomes from patient-derived GSCs in culture. We describe the steps required to stably express a tagged lysosomal protein in GSCs, mechanically lyse cells, magnetically immunopurify lysosomes, and qualitatively assess these organelles. We then detail the procedure for retrieving intact and purified lysosomes from GSCs. We also specify cell culture conditions, storage procedures, and sample preparation for immunoblotting. For complete details on the use and execution of this protocol, please refer to Maghe et al.1.
    Keywords:  Cancer; Cell Biology; Cell culture; Cell separation/fractionation; Molecular/Chemical Probes; Protein Biochemistry; Stem Cells
    DOI:  https://doi.org/10.1016/j.xpro.2024.103121
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