bims-auttor Biomed News
on Autophagy and mTOR
Issue of 2024–07–28
seventy papers selected by
Viktor Korolchuk, Newcastle University
  1. Spautin-1 promotes PINK1-PRKN-dependent mitophagy and improves associative learning capability in an alzheimer disease animal model.
  2. Cadmium targeting transcription factor EB to inhibit autophagy-lysosome function contributes to acute kidney injury.
  3. Autophagy and lysosomal dysfunction in diabetes and its complications.
  4. Autophagy in aging-related diseases and cancer: Principles, regulatory mechanisms and therapeutic potential.
  5. Targeting cellular mitophagy as a strategy for human cancers.
  6. The ubiquitin-proteasome system degrades fatty acid synthase under nitrogen starvation when autophagy is dysfunctional in Saccharomyces cerevisiae.
  7. The COPII coat protein SEC24D is required for autophagosome closure in mammals.
  8. Spermidine as an epigenetic regulator of autophagy in neurodegenerative disorders.
  9. Cholesterol-rich lysosomes induced by respiratory syncytial virus promote viral replication by blocking autophagy flux.
  10. Parkin, a Parkinson's disease-associated protein, mediates the mitophagy that plays a vital role in the pathophysiology of major depressive disorder.
  11. Age- and disease-related autophagy impairment in Huntington disease: New insights from direct neuronal reprogramming.
  12. The emerging significance of Vac8, a multi-purpose armadillo-repeat protein in yeast.
  13. Genotype-Specific Activation of Autophagy during Heat Wave in Wheat.
  14. Interplay among Oxidative Stress, Autophagy, and the Endocannabinoid System in Neurodegenerative Diseases: Role of the Nrf2- p62/SQSTM1 Pathway and Nutraceutical Activation.
  15. Integrating bioengineering, super-resolution microscopy and mechanobiology in autophagy research: addendum to the guidelines (4th edition).
  16. mTOR in metabolic homeostasis and disease.
  17. The AKT2/SIRT5/TFEB pathway as a potential therapeutic target in non-neovascular AMD.
  18. BOK-engaged mitophagy alleviates neuropathology in Alzheimer's disease.
  19. Coxiella burnetii inhibits nuclear translocation of TFEB, the master transcription factor for lysosomal biogenesis.
  20. The Multifaceted Interactions of Dictyostelium Atg1 with Mitochondrial Function, Endocytosis, Growth, and Development.
  21. Microglial AKAP8L: a key mediator in diabetes-associated cognitive impairment via autophagy inhibition and neuroinflammation triggering.
  22. Pseudoginsenoside-F11 reduces cognitive impairment and white matter injury in vascular dementia by alleviating autophagy-lysosomal pathway deficiency.
  23. Upregulation of peroxisome proliferator-activated receptor γ with resorcinol alleviates reactive oxygen species generation and lipid accumulation in neuropathic lysosomal storage diseases.
  24. PP2Ac Regulates Autophagy via Mediating mTORC1 and ULK1 During Osteoclastogenesis in the Subchondral Bone of Osteoarthritis.
  25. Lipid accumulation drives cellular senescence in dopaminergic neurons.
  26. Early metformin treatment: An effective approach for targeting fragile X syndrome pathophysiology.
  27. Autophagy aggravates multi-walled carbon nanotube-induced ferroptosis by suppressing PGC-1 dependent-mitochondrial biogenesis in lung epithelial cells.
  28. Assessment of Non-canonical Functions of the Autophagy Proteins in LC3-Associated Phagocytosis and LC3-Associated Endocytosis.
  29. ALS-linked VapB P56S mutation alters neuronal mitochondrial turnover at the synapse.
  30. The role of galectins in the regulation of autophagy and inflammasome in host immunity.
  31. Nitidine chloride inhibits mTORC1 signaling through ATF4-mediated Sestrin2 induction and targets IGF2R for lysosomal degradation.
  32. Arginine methylation of DDX3 by PRMT1 mediates mitochondrial homeostasis to promote breast cancer metastasis.
  33. GORASP2 promotes phagophore closure and autophagosome maturation into autolysosomes.
  34. ATM facilitates autophagy and protects against oxidative stress and apoptosis in response to ER stress in vitro.
  35. Mutant NOTCH3ECD Triggers Defects in Mitochondrial Function and Mitophagy in CADASIL Cell Models.
  36. CYYR1 promotes the degradation of the E3 ubiquitin ligase WWP1 and is associated with favorable prognosis in breast cancer.
  37. The Toxoplasma Effector GRA4 Hijacks Host TBK1 to Oppositely Regulate Anti-T. Gondii Immunity and Tumor Immunotherapy.
  38. Autophagy modulation in cancer therapy: Challenges coexist with opportunities.
  39. Connexin43 promotes exocytosis of damaged lysosomes through actin remodelling.
  40. All-trans retinoic acid induces lipophagy through reducing Rubicon in Hepa1c1c7 cells.
  41. Structural basis for TNIP1 binding to FIP200 during mitophagy.
  42. Cellular response during cellular starvation: A battle for cellular survivability.
  43. Astrocytic autophagy plasticity modulates Aβ clearance and cognitive function in Alzheimer's disease.
  44. Diphenylbutadiene Fluorescent Analogues in Sub-cellular Imaging and Monitoring Mitophagy.
  45. O-Sialoglycoprotein Endopeptidase Deficiency Impairs Proteostasis and Induces Autophagy in Human Embryonic Stem Cells.
  46. Advancements in Utilizing Natural Compounds for Modulating Autophagy in Liver Cancer: Molecular Mechanisms and Therapeutic Targets.
  47. Mechanisms of lipid droplet degradation.
  48. Fam134c and Fam134b shape axonal endoplasmic reticulum architecture in vivo.
  49. Spatial selectivity of ATase inhibition in mouse models of Charcot-Marie-Tooth disease.
  50. Nur77 improves ovarian function in reproductive aging mice by activating mitophagy and inhibiting apoptosis.
  51. Erlotinib Treatment in Colorectal Cancer Suppresses Autophagy Based on KRAS Mutation.
  52. The role and mechanism of action of miR‑92a in endothelial cell autophagy.
  53. Regulation of Mitochondria-Derived Immune Activation by 'Antiviral' TRIM Proteins.
  54. The Autophagic and Apoptotic Death of Forebrain Neurons of Rats with Global Brain Ischemia Is Diminished by the Intranasal Administration of Insulin: Possible Mechanism of Its Action.
  55. Targeting ferritinophagy impairs quiescent cancer stem cells in acute myeloid leukemia in vitro and in vivo models.
  56. Esrra regulates Rplp1-mediated translation of lysosome proteins suppressed in metabolic dysfunction-associated steatohepatitis and reversed by alternate day fasting.
  57. The Role of Polyphenols in Modulating Mitophagy: Implications for Therapeutic Interventions.
  58. MARCH1 negatively regulates TBK1-mTOR signaling pathway by ubiquitinating TBK1.
  59. Assessing the Presence of Phosphoinositides on Autophagosomal Membrane in Yeast by Live Cell Imaging.
  60. Targeting Cellular Adaptive Responses to Glutaminolysis Perturbation for Cancer Therapy.
  61. Iron regulatory protein 2 contributes to antimicrobial immunity by preserving lysosomal function in macrophages.
  62. The effect of intermittent fasting on preventing obesity-related early aging from a molecular and cellular perspective.
  63. Secondary interactions in ubiquitin-binding domains achieve linkage or substrate specificity.
  64. Gastrodin Improves the Activity of the Ubiquitin-Proteasome System and the Autophagy-Lysosome Pathway to Degrade Mutant Huntingtin.
  65. PKR Mediates the Mitochondrial Unfolded Protein Response through Double-Stranded RNA Accumulation under Mitochondrial Stress.
  66. UNVEILING DEFECTS OF SECRETION MECHANISMS IN PARKINSON'S DISEASE.
  67. TFEB/3 govern repair Schwann cell generation and function following peripheral nerve injury.
  68. Mutant mice with rod-specific VPS35 deletion exhibit retinal α-synuclein pathology-associated degeneration.
  69. Therapeutic effect of nicotinamide mononucleotide on Alzheimer's disease through activating autophagy and anti-oxidative stress.
  70. Natural Compounds for Preventing Age-Related Diseases and Cancers.
  1. Autophagy. 2024 Jul 25.
    Spautin-1 promotes PINK1-PRKN-dependent mitophagy and improves associative learning capability in an alzheimer disease animal model.
    Juan Yi, He-Ling Wang, Guang Lu, Hailong Zhang, Lina Wang, Zhen-Yu Li, Liming Wang, Yihua Wu, Dajing Xia, Evandro F Fang, Han-Ming Shen.
      Spautin-1 is a well-known macroautophagy/autophagy inhibitor via suppressing the deubiquitinases USP10 and USP13 and promoting the degradation of the PIK3C3/VPS34-BECN1 complex, while its effect on selective autophagy remains poorly understood. Mitophagy is a selective form of autophagy for removal of damaged and superfluous mitochondria via the autophagy-lysosome pathway. Here, we report a surprising discovery that, while spautin-1 remains as an effective autophagy inhibitor, it promotes PINK1-PRKN-dependent mitophagy induced by mitochondrial damage agents. Mechanistically, spautin-1 facilitates the stabilization and activation of the full-length PINK1 at the outer mitochondrial membrane (OMM) via binding to components of the TOMM complex (TOMM70 and TOMM20), leading to the disruption of the mitochondrial import of PINK1 and prevention of PARL-mediated PINK1 cleavage. Moreover, spautin-1 induces neuronal mitophagy in Caenorhabditis elegans (C. elegans) in a PINK-1-PDR-1-dependent manner. Functionally, spautin-1 is capable of improving associative learning capability in an Alzheimer disease (AD) C. elegans model. In summary, we report a novel function of spautin-1 in promoting mitophagy via the PINK1-PRKN pathway. As deficiency of mitophagy is closely implicated in the pathogenesis of neurodegenerative disorders, the pro-mitophagy function of spautin-1 might suggest its therapeutic potential in neurodegenerative disorders such as AD.
    Keywords:  Alzheimer’s disease; PINK1; TOMM complex; autophagy; mitophagy; spautin-1
    DOI:  https://doi.org/10.1080/15548627.2024.2383145
  2. J Adv Res. 2024 Jul 19. pii: S2090-1232(24)00297-2. [Epub ahead of print]
    Cadmium targeting transcription factor EB to inhibit autophagy-lysosome function contributes to acute kidney injury.
    Peng-Fei Dong, Tian-Bin Liu, Kai Chen, Dan Li, Yue Li, Cai-Yu Lian, Zhen-Yong Wang, Lin Wang.
       INTRODUCTION: Environmental and occupational exposure to cadmium (Cd) has been shown to cause acute kidney injury (AKI). Previous studies have demonstrated that autophagy inhibition and lysosomal dysfunction are important mechanisms of Cd-induced AKI.
    OBJECTIVES: Transcription factor EB (TFEB) is a critical transcription regulator that modulates autophagy-lysosome function, but its role in Cd-induced AKI is yet to be elucidated. Thus, in vivo and in vitro studies were conducted to clarify this issue.
    METHODS AND RESULTS: Data firstly showed that reduced TFEB expression and nuclear translocation were evident in Cd-induced AKI models, accompanied by autophagy-lysosome dysfunction. Pharmacological and genetic activation of TFEB improved Cd-induced AKI via alleviating autophagy inhibition and lysosomal dysfunction, whereas Tfeb knockdown further aggravated this phenomenon, suggesting the key role of TFEB in Cd-induced AKI by regulating autophagy. Mechanistically, Cd activated mechanistic target of rapamycin complex 1 (mTORC1) to enhance TFEB phosphorylation and thereby inhibiting TFEB nuclear translocation. Cd also activated chromosome region maintenance 1 (CRM1) to promote TFEB nuclear export. Meanwhile, Cd activated general control non-repressed protein 5 (GCN5) to enhance nuclear TFEB acetylation, resulting in the decreased TFEB transcriptional activity. Moreover, inhibition of CRM1 or GCN5 alleviated Cd-induced AKI by enhancing TFEB activity, respectively.
    CONCLUSION: In summary, these findings reveal that TFEB phosphorylation, nuclear export and acetylation independently suppress TFEB activity to cause Cd-induced AKI via regulating autophagy-lysosome function, suggesting that TFEB activation might be a promising treatment strategy for Cd-induced AKI.
    Keywords:  Acute kidney injury; Autophagy; Cadmium; Lysosome; transcription factor EB
    DOI:  https://doi.org/10.1016/j.jare.2024.07.013
  3. Trends Endocrinol Metab. 2024 Jul 24. pii: S1043-2760(24)00170-X. [Epub ahead of print]
    Autophagy and lysosomal dysfunction in diabetes and its complications.
    Catherine Arden, Seo H Park, Xaviera Riani Yasasilka, Eun Y Lee, Myung-Shik Lee.
      Autophagy is critical for energy homeostasis and the function of organelles such as endoplasmic reticulum (ER) and mitochondria. Dysregulated autophagy due to aging, environmental factors, or genetic predisposition can be an underlying cause of not only diabetes through β-cell dysfunction and metabolic inflammation, but also diabetic complications such as diabetic kidney diseases (DKDs). Dysfunction of lysosomes, effector organelles of autophagic degradation, due to metabolic stress or nutrients/metabolites accumulating in metabolic diseases is also emerging as a cause or aggravating element in diabetes and its complications. Here, we discuss the etiological role of dysregulated autophagy and lysosomal dysfunction in diabetes and a potential role of autophagy or lysosomal modulation as a new avenue for treatment of diabetes and its complications.
    Keywords:  autophagy; complications; diabetes; kidney diseases; lysosome
    DOI:  https://doi.org/10.1016/j.tem.2024.06.010
  4. Ageing Res Rev. 2024 Jul 20. pii: S1568-1637(24)00246-0. [Epub ahead of print] 102428
    Autophagy in aging-related diseases and cancer: Principles, regulatory mechanisms and therapeutic potential.
    Na Wu, Wenhui Zheng, Yundong Zhou, Yu Tian, Min Tang, Xiaoqiang Feng, Milad Ashrafizadeh, Yuzhuo Wang, Xiaojia Niu, Murtaza Tambuwala, Lingzhi Wang, Vinay Tergaonkar, Gautam Sethi, Daniel Klionsky, Li Huang, Ming Gu.
      Macroautophagy/autophagy is primarily accountable for the degradation of damaged organelles and toxic macromolecules in the cells. Regarding the essential function of autophagy for preserving cellular homeostasis, changes in, or dysfunction of, autophagy flux can lead to disease development. In the current paper, the complicated function of autophagy in aging-associated pathologies and cancer is evaluated, highlighting the underlying molecular mechanisms that can affect longevity and disease pathogenesis. As a natural biological process, a reduction in autophagy is observed with aging, resulting in an accumulation of cell damage and the development of different diseases, including neurological disorders, cardiovascular diseases, and cancer. The MTOR, AMPK, and ATG proteins demonstrate changes during aging, and they are promising therapeutic targets. Insulin/IGF1, TOR, PKA, AKT/PKB, caloric restriction and mitochondrial respiration are vital for lifespan regulation and can modulate or have an interaction with autophagy. The specific types of autophagy, such as mitophagy that degrades mitochondria, can regulate aging by affecting these organelles and eliminating those mitochondria with genomic mutations. Autophagy and its specific types contribute to the regulation of carcinogenesis and they are able to dually enhance or decrease cancer progression. Cancer hallmarks, including proliferation, metastasis, therapy resistance and immune reactions, are tightly regulated by autophagy, supporting the conclusion that autophagy is a promising target in cancer therapy.
    Keywords:  Aging; autophagy; cancer therapy; cell death; longevity
    DOI:  https://doi.org/10.1016/j.arr.2024.102428
  5. Front Cell Dev Biol. 2024 ;12 1431968
    Targeting cellular mitophagy as a strategy for human cancers.
    Yuming Dong, Xue Zhang.
      Mitophagy is the cellular process to selectively eliminate dysfunctional mitochondria, governing the number and quality of mitochondria. Dysregulation of mitophagy may lead to the accumulation of damaged mitochondria, which plays an important role in the initiation and development of tumors. Mitophagy includes ubiquitin-dependent pathways mediated by PINK1/Parkin and non-ubiquitin dependent pathways mediated by mitochondrial autophagic receptors including NIX, BNIP3, and FUNDC1. Cellular mitophagy widely participates in multiple cellular process including metabolic reprogramming, anti-tumor immunity, ferroptosis, as well as the interaction between tumor cells and tumor-microenvironment. And cellular mitophagy also regulates tumor proliferation and metastasis, stemness, chemoresistance, resistance to targeted therapy and radiotherapy. In this review, we summarized the underlying molecular mechanisms of mitophagy and discussed the complex role of mitophagy in diverse contexts of tumors, indicating it as a promising target in the mitophagy-related anti-tumor therapy.
    Keywords:  PINK1; cancer; mitochondria; mitophagy; stemness
    DOI:  https://doi.org/10.3389/fcell.2024.1431968
  6. Biochem Biophys Res Commun. 2024 Jul 18. pii: S0006-291X(24)00959-8. [Epub ahead of print]733 150423
    The ubiquitin-proteasome system degrades fatty acid synthase under nitrogen starvation when autophagy is dysfunctional in Saccharomyces cerevisiae.
    Hae-Soo Jang, Yongook Lee, Yeonsoo Kim, Won-Ki Huh.
      Autophagy and the ubiquitin-proteasome system (UPS) are two major protein quality control mechanisms maintaining cellular proteostasis. In Saccharomyces cerevisiae, the de novo synthesis of saturated fatty acids is performed by a multienzyme complex known as fatty acid synthase (FAS). A recent study reported that yeast FAS is preferentially degraded by autophagy under nitrogen starvation. In this study, we examined the fate of FAS during nitrogen starvation when autophagy is dysfunctional. We found that the UPS compensates for FAS degradation in the absence of autophagy. Additionally, we discovered that the UPS-dependent degradation of Fas2 requires the E3 ubiquitin ligase Ubr1. Our findings highlight the complementary relationship between autophagy and the UPS.
    Keywords:  Autophagy; Fatty acid synthase; Nitrogen starvation; Saccharomyces cerevisiae; Ubiquitin-proteasome system
    DOI:  https://doi.org/10.1016/j.bbrc.2024.150423
  7. FEBS Lett. 2024 Jul 26.
    The COPII coat protein SEC24D is required for autophagosome closure in mammals.
    Tianlong He, Cuicui Ji, Wenting Zhang, Xianghua Li, Yukun Liu, Xiaoli Wang, Haolin Zhang, Juan Wang.
      Macroautophagy involves the encapsulation of cellular components within double-membrane autophagosomes for subsequent degradation in vacuoles or lysosomes. Coat protein complex II (COPII) vesicles serve as a membrane source for autophagosome formation. However, the specific role of SEC24D, an isoform of the COPII coat protein SEC24, in the macroautophagy pathway remains unclear. In this study, we demonstrate that SEC24D is indispensable for macroautophagy and important for autophagosome closure. Depletion of SEC24D leads to the accumulation of unsealed isolation membranes. Furthermore, under conditions of starvation, SEC24D interacts with casein kinase1 delta (CK1δ), a member of the casein kinase 1 family, and autophagy-related 9A (ATG9A). Collectively, our findings unveil the indispensable role of SEC24D in starvation-induced autophagy in mammalian cells.
    Keywords:  COPII; SEC24D; autophagosome closure; autophagy; isolation membrane
    DOI:  https://doi.org/10.1002/1873-3468.14983
  8. Eur J Pharmacol. 2024 Jul 18. pii: S0014-2999(24)00512-0. [Epub ahead of print]979 176823
    Spermidine as an epigenetic regulator of autophagy in neurodegenerative disorders.
    Sairaj Satarker, Joel Wilson, Kiran Kumar Kolathur, Jayesh Mudgal, Shaila A Lewis, Devinder Arora, Madhavan Nampoothiri.
      Autophagy is an abnormal protein degradation and recycling process that is impaired in various neurological diseases like Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease. Spermidine is a natural polyamine found in various plant- and meat-based diets that can induce autophagy, and is decreased in various neurodegenerative diseases. It acts on epigenetic enzymes like E1A-binding protein p300, HAT enzymes like Iki3p and Sas3p, and α-tubulin acetyltransferase 1 that modulate autophagy. Histone modifications like acetylation, phosphorylation, and methylation could influence autophagy. Autophagy is epigenetically regulated in various neurodegenerative disorders with many epigenetic enzymes and miRNAs. Polyamine regulation plays an essential role in the disease pathogenesis of AD and PD. Therefore, in this review, we discuss various enzymes and miRNAs involved in the epigenetic regulation of autophagy in neurodegenerative disorders and the role of spermidine as an autophagy enhancer. The alterations in spermidine-mediated regulation of Beclin-1, LC3-II, and p62 genes in AD and other PD-associated enzymes could impact the process of autophagy in these neurodegenerative diseases. With the ever-growing data and such promising effects of spermidine in autophagy, we feel it could be a promising target in this area and worth further detailed studies.
    Keywords:  Alzheimer's disease; Autophagy; Epigenetics; Neurodegenerative disorders; Parkinson's disease; Spermidine; miRNA
    DOI:  https://doi.org/10.1016/j.ejphar.2024.176823
  9. Nat Commun. 2024 Jul 26. 15(1): 6311
    Cholesterol-rich lysosomes induced by respiratory syncytial virus promote viral replication by blocking autophagy flux.
    Lifeng Chen, Jingjing Zhang, Weibin Xu, Jiayi Chen, Yujun Tang, Si Xiong, Yaolan Li, Hong Zhang, Manmei Li, Zhong Liu.
      Respiratory syncytial virus (RSV) hijacks cholesterol or autophagy pathways to facilitate optimal replication. However, our understanding of the associated molecular mechanisms remains limited. Here, we show that RSV infection blocks cholesterol transport from lysosomes to the endoplasmic reticulum by downregulating the activity of lysosomal acid lipase, activates the SREBP2-LDLR axis, and promotes uptake and accumulation of exogenous cholesterol in lysosomes. High cholesterol levels impair the VAP-A-binding activity of ORP1L and promote the recruitment of dynein-dynactin, PLEKHM1, or HOPS VPS39 to Rab7-RILP, thereby facilitating minus-end transport of autophagosomes and autolysosome formation. Acidification inhibition and dysfunction of cholesterol-rich lysosomes impair autophagy flux by inhibiting autolysosome degradation, which promotes the accumulation of RSV fusion protein. RSV-F storage is nearly abolished after cholesterol depletion or knockdown of LDLR. Most importantly, the knockout of LDLR effectively inhibits RSV infection in vivo. These findings elucidate the molecular mechanism of how RSV co-regulates lysosomal cholesterol reprogramming and autophagy and reveal LDLR as a novel target for anti-RSV drug development.
    DOI:  https://doi.org/10.1038/s41467-024-50711-4
  10. Neurochem Int. 2024 Jul 22. pii: S0197-0186(24)00135-9. [Epub ahead of print]179 105808
    Parkin, a Parkinson's disease-associated protein, mediates the mitophagy that plays a vital role in the pathophysiology of major depressive disorder.
    Yi Zhang.
      Depression is a complex mood disorder with multifactorial etiology and is also the most frequent non-motor symptom of Parkinson's disease. Emerging research suggests a potential link between mitochondrial dysfunction and the pathophysiology of major depressive disorder. By synthesizing current knowledge and research findings, this review sheds light on the intricate relationship between Parkin, a protein classically associated with Parkinson's disease, and mitochondrial quality control mechanisms (e.g., mitophagy, mitochondrial biogenesis, and mitochondrial dynamic), specifically focusing on their relevance in the context of depression. Additionally, the present review discusses therapeutic strategies targeting Parkin-medicated mitophagy and calls for further research in this field. These findings suggest promise for the development of novel depression treatments through modulating Parkin-mediated mitophagy.
    Keywords:  Major depressive disorder; Mitochondrial biogenesis; Mitochondrial dynamics; Mitochondrial quality control; Mitophagy; Parkin
    DOI:  https://doi.org/10.1016/j.neuint.2024.105808
  11. Aging Cell. 2024 Jul 23. e14285
    Age- and disease-related autophagy impairment in Huntington disease: New insights from direct neuronal reprogramming.
    Chuyang Luo, Junsheng Yang.
      Autophagy impairment in Huntington disease (HD) has been reported for almost two decades. However, the molecular mechanisms underlying this phenomenon are still unclear. This is partially because it is challenging to model the impact of the disease-causing mutation, aging, as well as the selective vulnerability of neurons in a single model. Recently developed direct neuronal reprogramming that allows researchers to induce neurons-of-interest retaining biological aging information made it possible to establish HD cellular models to study more relevant age- and disease-related molecular changes in neurons. We here summarized the findings from a few latest studies utilizing directly reprogrammed HD neurons and discussed the new insights they brought to the understanding of the age- and disease-related autophagy impairment in HD.
    Keywords:  Huntington disease; aging; autophagy; direct neuronal reprogramming
    DOI:  https://doi.org/10.1111/acel.14285
  12. Autophagy. 2024 Jul 24. 1-4
    The emerging significance of Vac8, a multi-purpose armadillo-repeat protein in yeast.
    Hana Popelka, Daniel J Klionsky.
      Vac8 is the sole armadillo-repeat (ARM) protein in yeast. The function of Vac8 in the cytoplasm-to-vacuole targeting pathway has been known for a long time but its role in the phagophore assembly site localization and recruitment of autophagy-related protein complexes is slowly coming to light. Because Vac8 is also involved in formation of the nuclear-vacuole junction and vacuole inheritance, the protein needs to be a competent and wide-ranging mediator of cellular processes. In this article, we discuss two recent studies reporting on Vac8 and its binding partners. We describe Vac8 in the context of crystallized protein complexes as well as predicted models to reveal the versatility of Vac8 and its potential to become a subject of future autophagy research.Abbreviation: ARM, armadillo repeat; Cvt, cytoplasm-to-vacuole targeting; IDPR, intrinsically disordered protein region NVJ, nucleus-vacuole junction; SEC, size-exclusion chromatography.
    Keywords:  Atg13; Atg14; Nvj1; Vac17; crystal structure
    DOI:  https://doi.org/10.1080/15548627.2024.2377377
  13. Cells. 2024 Jul 20. pii: 1226. [Epub ahead of print]13(14):
    Genotype-Specific Activation of Autophagy during Heat Wave in Wheat.
    Kathleen Hickey, Yunus Şahin, Glenn Turner, Taras Nazarov, Vadim Jitkov, Mike Pumphrey, Andrei Smertenko.
      Recycling of unnecessary or dysfunctional cellular structures through autophagy plays a critical role in cellular homeostasis and environmental resilience. Therefore, the autophagy trait may have been unintentionally selected in wheat breeding programs for higher yields in arid climates. This hypothesis was tested by measuring the response of three common autophagy markers, ATG7, ATG8, and NBR1, to a heat wave under reduced soil moisture content in 16 genetically diverse spring wheat landraces originating from different geographical locations. We observed in the greenhouse trials that ATG8 and NBR1 exhibited genotype-specific responses to a 1 h, 40 °C heat wave, while ATG7 did not show a consistent response. Three genotypes from Uruguay, Mozambique, and Afghanistan showed a pattern consistent with higher autophagic activity: decreased or stable abundance of both ATG8 and NBR1 proteins, coupled with increased transcription of ATG8 and NBR1. In contrast, three genotypes from Pakistan, Ethiopia, and Egypt exhibited elevated ATG8 protein levels alongside reduced or unaltered ATG8 transcript levels, indicating a potential suppression or no change in autophagic activity. Principal component analysis demonstrated a correlation between lower abundance of ATG8 and NBR1 proteins and higher yield in the field trials. We found that (i) the combination of heat and drought activated autophagy only in several genotypes, suggesting that despite being a resilience mechanism, autophagy is a heat-sensitive process; (ii) higher autophagic activity correlates positively with greater yield; (iii) the lack of autophagic activity in some high-yielding genotypes suggests contribution of alternative stress-resilient mechanisms; and (iv) enhanced autophagic activity in response to heat and drought was independently selected by wheat breeding programs in different geographic locations.
    Keywords:  ATG7; ATG8; NBR1; autophagy; drought; heat; tolerance; yield
    DOI:  https://doi.org/10.3390/cells13141226
  14. Curr Issues Mol Biol. 2024 Jul 02. 46(7): 6868-6884
    Interplay among Oxidative Stress, Autophagy, and the Endocannabinoid System in Neurodegenerative Diseases: Role of the Nrf2- p62/SQSTM1 Pathway and Nutraceutical Activation.
    Federica Armeli, Beatrice Mengoni, Debra L Laskin, Rita Businaro.
      The onset of neurodegenerative diseases involves a complex interplay of pathological mechanisms, including protein aggregation, oxidative stress, and impaired autophagy. This review focuses on the intricate connection between oxidative stress and autophagy in neurodegenerative disorders, highlighting autophagy as pivotal in disease pathogenesis. Reactive oxygen species (ROS) play dual roles in cellular homeostasis and autophagy regulation, with disruptions of redox signaling contributing to neurodegeneration. The activation of the Nrf2 pathway represents a critical antioxidant mechanism, while autophagy maintains cellular homeostasis by degrading altered cell components. The interaction among p62/SQSTM1, Nrf2, and Keap1 forms a regulatory pathway essential for cellular stress response, whose dysregulation leads to impaired autophagy and aggregate accumulation. Targeting the Nrf2-p62/SQSTM1 pathway holds promise for therapeutic intervention, mitigating oxidative stress and preserving cellular functions. Additionally, this review explores the potential synergy between the endocannabinoid system and Nrf2 signaling for neuroprotection. Further research is needed to elucidate the involved molecular mechanisms and develop effective therapeutic strategies against neurodegeneration.
    Keywords:  Nrf2; autophagy; endocannabinoid system; neurodegenerative diseases; neuroinflammation; neuroprotection; nutraceuticals; oxidative stress; p62/SQSTM1
    DOI:  https://doi.org/10.3390/cimb46070410
  15. Autophagy. 2024 Jul 20. 1-4
    Integrating bioengineering, super-resolution microscopy and mechanobiology in autophagy research: addendum to the guidelines (4th edition).
    Andrea Ravasio, Daniel J Klionsky, Cristina Bertocchi.
      Recent key technological developments, such as super-resolution microscopy and microfabrication, enabled investigation of biological processes, including macroautophagy/autophagy, with unprecedented spatiotemporal resolution and control over experimental conditions. Such disruptive innovations deepened our capability to provide mechanistic understandings of the autophagic process and its causes. This addendum aims to expand the guidelines on autophagy in three key directions: optical methods enabling visualization of autophagic machinery beyond the diffraction-limited resolution; bioengineering enabling accurate designs and control over experimental conditions; and theoretical advances in mechanobiology connecting autophagy and mechanical processes of the cell. Abbreviation: 3D: three-dimensional; SIM: structured illumination microscopy; STORM: stochastic optical reconstruction microscopy.
    Keywords:  Bioengineering; interdisciplinarity; mechanoautophagy; microfabrication; microfluidics; super-resolution microscopy
    DOI:  https://doi.org/10.1080/15548627.2024.2379065
  16. Exp Cell Res. 2024 Jul 22. pii: S0014-4827(24)00264-7. [Epub ahead of print] 114173
    mTOR in metabolic homeostasis and disease.
    Xuejia Liu, Bin Guo, Qiye Li, Jing Nie.
      The ability to maintain cellular metabolic homeostasis is critical to life, in which mTOR plays an important role. This kinase integrates upstream nutrient signals and performs essential functions in physiology and metabolism by increasing metabolism and suppressing autophagy. Thus, dysregulation of mTOR activity leads to diseases, especially metabolic diseases such as cancer, type 2 diabetes and neurological disorders. Therefore, inhibition of overactivated mTOR becomes a rational approach to treat a variety of metabolic diseases. In this review, we discuss how mTOR responds to upstream signals and how mTOR regulates metabolic processes, including protein, nucleic acid, and lipid metabolism. Furthermore, we discuss the possible causes and consequences of dysregulated mTOR signaling activity, and summarize relevant applications, such as inhibition of mTOR activity to treat these diseases. This review will advance our comprehensive knowledge of the association between mTOR and metabolic homeostasis, which has significant ramifications for human health.
    Keywords:  mTOR; mTOR inhibitor; mTORC1; mTORC2; metabolic homeostasis
    DOI:  https://doi.org/10.1016/j.yexcr.2024.114173
  17. Nat Commun. 2024 Jul 21. 15(1): 6150
    The AKT2/SIRT5/TFEB pathway as a potential therapeutic target in non-neovascular AMD.
    Sayan Ghosh, Ruchi Sharma, Sridhar Bammidi, Victoria Koontz, Mihir Nemani, Meysam Yazdankhah, Katarzyna M Kedziora, Donna Beer Stolz, Callen T Wallace, Cheng Yu-Wei, Jonathan Franks, Devika Bose, Peng Shang, Helena M Ambrosino, James R Dutton, Zhaohui Geng, Jair Montford, Jiwon Ryu, Dhivyaa Rajasundaram, Stacey Hose, José-Alain Sahel, Rosa Puertollano, Toren Finkel, J Samuel Zigler, Yuri Sergeev, Simon C Watkins, Eric S Goetzman, Deborah A Ferrington, Miguel Flores-Bellver, Kai Kaarniranta, Akrit Sodhi, Kapil Bharti, James T Handa, Debasish Sinha.
      Non-neovascular or dry age-related macular degeneration (AMD) is a multi-factorial disease with degeneration of the aging retinal-pigmented epithelium (RPE). Lysosomes play a crucial role in RPE health via phagocytosis and autophagy, which are regulated by transcription factor EB/E3 (TFEB/E3). Here, we find that increased AKT2 inhibits PGC-1α to downregulate SIRT5, which we identify as an AKT2 binding partner. Crosstalk between SIRT5 and AKT2 facilitates TFEB-dependent lysosomal function in the RPE. AKT2/SIRT5/TFEB pathway inhibition in the RPE induced lysosome/autophagy signaling abnormalities, disrupted mitochondrial function and induced release of debris contributing to drusen. Accordingly, AKT2 overexpression in the RPE caused a dry AMD-like phenotype in aging Akt2 KI mice, as evident from decline in retinal function. Importantly, we show that induced pluripotent stem cell-derived RPE encoding the major risk variant associated with AMD (complement factor H; CFH Y402H) express increased AKT2, impairing TFEB/TFE3-dependent lysosomal function. Collectively, these findings suggest that targeting the AKT2/SIRT5/TFEB pathway may be an effective therapy to delay the progression of dry AMD.
    DOI:  https://doi.org/10.1038/s41467-024-50500-z
  18. Brain. 2024 Jul 25. pii: awae241. [Epub ahead of print]
    BOK-engaged mitophagy alleviates neuropathology in Alzheimer's disease.
    Yang Yang, Hui Chen, Shuwen Huang, Hao Chen, Alexei Verkhratsky, Jianqin Niu, Yibo Qu, Chenju Yi.
      Mitochondrial malfunction associated with impaired mitochondrial quality control and self-renewal machinery, known as mitophagy, is an under-appreciated mechanism precipitating synaptic loss and cognitive impairments in Alzheimer's disease (AD). Promoting mitophagy has been shown to improve cognitive function in AD animals. However, the regulatory mechanism was unclear, which formed the aim of this study. Here, we found that a neuron-specific loss of Bcl-2 family member BOK in AD patients and APPswe/PS1dE9 (APP/PS1) mice is closely associated with mitochondrial damage and mitophagy defects. We further revealed that BOK is the key to the Parkin-mediated mitophagy through competitive binding to the MCL1/Parkin complex, resulting in Parkin release and translocation to damaged mitochondria to initiate mitophagy. Furthermore, overexpressing bok in hippocampal neurons of APP/PS1 mice alleviated mitophagy and mitochondrial malfunction, resulting in improved cognitive function. Conversely, the knockdown of bok worsened the aforementioned AD-related changes. Our findings uncover a novel mechanism of BOK signaling through regulating Parkin-mediated mitophagy to mitigate amyloid pathology, mitochondrial and synaptic malfunctions, and cognitive decline in AD, thus representing a promising therapeutic target.
    Keywords:  amyloid-β; cognitive decline; mitochondrial dysfunction; mitophagy; synaptophysin loss
    DOI:  https://doi.org/10.1093/brain/awae241
  19. J Bacteriol. 2024 Jul 26. e0015024
    Coxiella burnetii inhibits nuclear translocation of TFEB, the master transcription factor for lysosomal biogenesis.
    Brigham Killips, Emily J Bremer Heaton, Leonardo Augusto, Anders Omsland, Stacey D Gilk.
      Coxiella burnetii is a highly infectious, Gram-negative, obligate intracellular bacterium and the causative agent of human Q fever. The Coxiella Containing Vacuole (CCV) is a modified phagolysosome that forms through fusion with host endosomes and lysosomes. While an initial acidic pH < 4.7 is essential to activate Coxiella metabolism, the mature, growth-permissive CCV has a luminal pH of ~5.2 that remains stable throughout infection. Inducing CCV acidification to a lysosomal pH (~4.7) causes Coxiella degradation, suggesting that Coxiella regulates CCV pH. Supporting this hypothesis, Coxiella blocks host lysosomal biogenesis, leading to fewer host lysosomes available to fuse with the CCV. Host cell lysosome biogenesis is primarily controlled by the transcription factor EB (TFEB), which binds Coordinated Lysosomal Expression And Regulation (CLEAR) motifs upstream of genes involved in lysosomal biogenesis and function. TFEB is a member of the microphthalmia/transcription factor E (MiT/TFE) protein family, which also includes MITF, TFE3, and TFEC. This study examines the roles of MiT/TFE proteins during Coxiella infection. We found that in cells lacking TFEB, both Coxiella growth and CCV size increase. Conversely, TFEB overexpression or expression in the absence of other family members leads to significantly less bacterial growth and smaller CCVs. TFE3 and MITF do not appear to play a significant role during Coxiella infection. Surprisingly, we found that Coxiella actively blocks TFEB nuclear translocation in a Type IV Secretion System-dependent manner, thus decreasing lysosomal biogenesis. Together, these results suggest that Coxiella inhibits TFEB nuclear translocation to limit lysosomal biogenesis, thus avoiding further CCV acidification through CCV-lysosomal fusion.
    IMPORTANCE: The obligate intracellular bacterial pathogen Coxiella burnetii causes the zoonotic disease Q fever, which is characterized by a debilitating flu-like illness in acute cases and life-threatening endocarditis in patients with chronic disease. While Coxiella survives in a unique lysosome-like vacuole called the Coxiella Containing Vacuole (CCV), the bacterium inhibits lysosome biogenesis as a mechanism to avoid increased CCV acidification. Our results establish that transcription factor EB (TFEB), a member of the microphthalmia/transcription factor E (MiT/TFE) family of transcription factors that regulate lysosomal gene expression, restricts Coxiella infection. Surprisingly, Coxiella blocks TFEB translocation from the cytoplasm to the nucleus, thus downregulating the expression of lysosomal genes. These findings reveal a novel bacterial mechanism to regulate lysosomal biogenesis.
    Keywords:  CCV; Coxiella burnetii; MITF; TFE3; TFEB; lysosome
    DOI:  https://doi.org/10.1128/jb.00150-24
  20. Cells. 2024 Jul 14. pii: 1191. [Epub ahead of print]13(14):
    The Multifaceted Interactions of Dictyostelium Atg1 with Mitochondrial Function, Endocytosis, Growth, and Development.
    Melodi Gizem Sen, Oana Sanislav, Paul Robert Fisher, Sarah Jane Annesley.
      Autophagy is a degradative recycling process central to the maintenance of homeostasis in all eukaryotes. By ensuring the degradation of damaged mitochondria, it plays a key role in maintaining mitochondrial health and function. Of the highly conserved autophagy proteins, autophagy-related protein 1 (Atg1) is essential to the process. The involvement of these proteins in intracellular signalling pathways, including those involving mitochondrial function, are still being elucidated. Here the role of Atg1 was investigated in the simple model organism Dictyostelium discoideum using an atg1 null mutant and mutants overexpressing or antisense-inhibiting atg1. When evaluated against the well-characterised outcomes of mitochondrial dysfunction in this model, altered atg1 expression resulted in an unconventional set of phenotypic outcomes in growth, endocytosis, multicellular development, and mitochondrial homeostasis. The findings here show that Atg1 is involved in a tightly regulated signal transduction pathway coordinating energy-consuming processes such as cell growth and multicellular development, along with nutrient status and energy production. Furthermore, Atg1's effects on energy homeostasis indicate a peripheral ancillary role in the mitochondrial signalling network, with effects on energy balance rather than direct effects on electron transport chain function. Further research is required to tease out these complex networks. Nevertheless, this study adds further evidence to the theory that autophagy and mitochondrial signalling are not opposing but rather linked, yet strictly controlled, homeostatic mechanisms.
    Keywords:  Atg1; Dictyostelium; autophagy; development; mitochondrial signalling
    DOI:  https://doi.org/10.3390/cells13141191
  21. J Neuroinflammation. 2024 Jul 20. 21(1): 177
    Microglial AKAP8L: a key mediator in diabetes-associated cognitive impairment via autophagy inhibition and neuroinflammation triggering.
    Wen-Yuan Zhang, Qian-Qian Wei, Tao Zhang, Chang-Shui Wang, Jing Chen, Jian-Hua Wang, Xin Xie, Pei Jiang.
       BACKGROUND: Diabetes-associated cognitive impairment (DACI) poses a significant challenge to the self-management of diabetes, markedly elevating the risk of adverse complications. A burgeoning body of evidence implicates microglia as a central player in the pathogenesis of DACI.
    METHODS: We utilized proteomics to identify potential biomarkers in high glucose (HG)-treated microglia, followed by gene knockdown techniques for mechanistic validation in vitro and in vivo.
    RESULTS: Our proteomic analysis identified a significant upregulation of AKAP8L in HG-treated microglia, with concurrent dysregulation of autophagy and inflammation markers, making AKAP8L a novel biomarker of interest. Notably, the accumulation of AKAP8L was specific to HG-treated microglia, with no observed changes in co-cultured astrocytes or neurons, a pattern that was mirrored in streptozotocin (STZ)-induced diabetic mice. Further studies through co-immunoprecipitation and proximity ligation assay indicated that the elevated AKAP8L in HG-treated microglial cells interacts with the mTORC1. In the STZ mouse model, we demonstrated that both AKAP8L knockdown and rapamycin treatment significantly enhanced cognitive function, as evidenced by improved performance in the Morris water maze, and reduced microglial activation. Moreover, these interventions effectively suppressed mTORC1 signaling, normalized autophagic flux, mitigated neuroinflammation, and decreased pyroptosis.
    CONCLUSIONS: Our findings highlight the critical role of AKAP8L in the development of DACI. By interacting with mTORC1, AKAP8L appears to obstruct autophagic processes and initiate a cascade of neuroinflammatory responses. The identification of AKAP8L as a key mediator in DACI opens up new avenues for potential therapeutic interventions.
    Keywords:  AKAP8L; Autophagy; Diabetes-associated cognitive impairment; Microglia; Neuroinflammation; mTOR
    DOI:  https://doi.org/10.1186/s12974-024-03170-z
  22. Phytomedicine. 2024 Jul 25. pii: S0944-7113(24)00541-5. [Epub ahead of print]133 155883
    Pseudoginsenoside-F11 reduces cognitive impairment and white matter injury in vascular dementia by alleviating autophagy-lysosomal pathway deficiency.
    Huiyang Wang, Yueyang Liu, Minghui Cui, Zhenkun Guo, Yang Zhao, Jingyu Yang, Chunfu Wu.
       BACKGROUND: Vascular dementia (VaD) resulting from chronic cerebral hypoperfusion (CCH) induces cognitive impairment and white matter injury (WMI). We previously found that CCH induces dysfunction of the autophagy-lysosomal pathway (ALP) in white matter (WM) of rats. Enhancing oligodendrocyte autophagy to counteract ALP deficiency is beneficial for cognitive recovery. Pseudogenoside-F11 (PF11), a saponin extracted from Panax quinquefolium l., provides neuroprotective benefits in many animal models of cerebral ischemia and dementia.
    PURPOSE: To investigate how PF11 affects cognitive deterioration in rats with VaD induced by two vessel occlusion (2VO), and to determine if PF11 regulates ALP dysfunction in WM.
    METHODS: CCH-related VaD was induced in rats using the 2VO method. PF11 (6, 12, 24 mg/kg, intragastric administration) was given continuously for 4 weeks postoperatively. Behavioral tests related to cognitive function were performed on the 28th day following 2VO. Transmission electron microscopy, immunofluorescence, western blotting and Luxol fast blue staining were used to assess the WMI and the mechanism of action of PF11 in 2VO-induced VaD.
    RESULTS: PF11 (12 mg/kg) ameliorated 2VO-induced cognitive impairment. PF11 also alleviated WMI on the 28th day following 2VO, as characterized by reduction of neuronal axonal demyelination and axonal loss. Furthermore, PF11 prevented mature oligodendrocytes death by attenuating ALP deficiency in WM on the 14th day following 2VO, as manifested by enhancement of mechanistic target of rapamycin-mediated autophagy and lysosomal function, thereby reducing the aberrant accumulation of autophagy substrates and increasing the level of autophagosomes in WM. In addition, PF11 also prevented microglia and astrocytes from activating in WM on the 28th day following 2VO.
    CONCLUSION: PF11 significantly ameliorates cognitive impairment and WMI, and the mechanism is at least partly related to lessening ALP dysfunction in WM by enhancing autophagy and reducing lysosomal defects in oligodendrocytes.
    Keywords:  Autophagy-lysosomal pathway; Cognitive impairment; Oligodendrocyte; Pseudoginsenoside-F11; Vascular dementia; White matter
    DOI:  https://doi.org/10.1016/j.phymed.2024.155883
  23. Int J Biochem Cell Biol. 2024 Jul 20. pii: S1357-2725(24)00123-7. [Epub ahead of print]174 106631
    Upregulation of peroxisome proliferator-activated receptor γ with resorcinol alleviates reactive oxygen species generation and lipid accumulation in neuropathic lysosomal storage diseases.
    Hyungkuen Kim, Sung-Jo Kim.
      Neuropathic lysosomal storage diseases (NLSDs), including ceroid lipofuscinosis neuronal 3 (CLN3) disease and Gaucher disease type 2 (GD2), are typically present in adolescents; however, there are no approved therapies. CLN3 disease is the most common of the 13 types of neuronal ceroid lipofuscinosis, and Gaucher disease is the most common type of lysosomal storage disease. These NLSDs share oxidative stress and lysosomal dysfunction with Parkinson's disease. In this study, we used patient-derived cells (PDCs) and resorcinol to develop a therapeutic agent based on peroxisome proliferator-activated receptor γ (PPARγ) activation. PPARγ is a major regulator of autophagy and reactive oxygen species (ROS). Resorcinol, a polyphenolic compound, has been reported to exhibit PPARγ agonistic potential. Protein levels were analyzed by immunoblotting and immunofluorescence microscopy. Changes in cellular metabolism, including ROS levels, lipid droplet content, and lysosomal activity, were measured by flow cytometry. Resorcinol reduced ROS levels by suppressing hypoxia-inducible factor 1α levels in CLN3-PDCs. Resorcinol upregulated autophagy and reduced lipid accumulation in CLN3-PDCs; however, these effects were abolished by autophagy inhibitors. Resorcinol increased nuclear PPARγ levels in CLN3-PDCs, and PPARγ antagonists abolished the therapeutic effects of resorcinol. Moreover, Resorcinol upregulated nuclear PPARγ levels and lysosomal activity in GD2-PDCs, and reduced lipid accumulation and ROS levels. In summary, resorcinol alleviated the shared pathogenesis of CLN3 disease and GD2 through PPARγ upregulation. These findings suggest that resorcinol is a potential therapeutic candidate for alleviating NLSD progression.
    Keywords:  Gaucher disease; Lipid droplet; Lysosomal storage disease; Neuronal ceroid lipofuscinosis; Oxidative stress; Peroxisome proliferator-activated receptor γ; Resorcinol
    DOI:  https://doi.org/10.1016/j.biocel.2024.106631
  24. Adv Sci (Weinh). 2024 Jul 23. e2404080
    PP2Ac Regulates Autophagy via Mediating mTORC1 and ULK1 During Osteoclastogenesis in the Subchondral Bone of Osteoarthritis.
    Haifeng Zhang, Gaoran Ge, Wei Zhang, Houyi Sun, Xiaolong Liang, Yu Xia, Jiacheng Du, Zerui Wu, Jiaxiang Bai, Huilin Yang, Xing Yang, Jun Zhou, Yaozeng Xu, Dechun Geng.
      The molecular mechanism underlying abnormal osteoclastogenesis triggering subchondral bone remodeling in osteoarthritis (OA) is still unclear. Here, single-cell and bulk transcriptomics sequencing analyses are performed on GEO datasets to identify key molecules and validate them using knee joint tissues from OA patients and rat OA models. It is found that the catalytic subunit of protein phosphatase 2A (PP2Ac) is highly expressed during osteoclastogenesis in the early stage of OA and is correlated with autophagy. Knockdown or inhibition of PP2Ac weakened autophagy during osteoclastogenesis. Furthermore, the ULK1 expression of the downstream genes is significantly increased when PP2Ac is knocked down. PP2Ac-mediated autophagy is dependent on ULK1 phosphorylation activity during osteoclastogenesis, which is associated with enhanced dephosphorylation of ULK1 Ser637 residue regulating at the post-translational level. Additionally, mTORC1 inhibition facilitated the expression level of PP2Ac during osteoclastogenesis. In animal OA models, decreasing the expression of PP2Ac ameliorated early OA progression. The findings suggest that PP2Ac is also a promising therapeutic target in early OA.
    Keywords:  PP2Ac; ULK1; autophagy; dephosphorylation; mTORC1; osteoclastogenesis
    DOI:  https://doi.org/10.1002/advs.202404080
  25. Aging (Albany NY). 2024 Jul 19. undefined
    Lipid accumulation drives cellular senescence in dopaminergic neurons.
    Taylor Russo, Markus Riessland.
      Parkinson's disease (PD) is an age-related movement disorder caused by the loss of dopaminergic (DA) neurons of the substantia nigra pars compacta (SNpc) of the midbrain, however, the underlying cause(s) of this DA neuron loss in PD is unknown and there are currently no effective treatment options to prevent or slow neuronal loss or the progression of related symptoms. It has been shown that both environmental factors as well as genetic predispositions underpin PD development and recent research has revealed that lysosomal dysfunction and lipid accumulation are contributors to disease progression, where an age-related aggregation of alpha-synuclein as well as lipids have been found in PD patients. Interestingly, the most common genetic risk factor for PD is Glucosylceramidase Beta 1 (GBA), which encodes a lysosomal glucocerebrosidase (GCase) that cleaves the beta-glucosidic linkage of lipids known as glucocerebrosides (GluCer). We have recently discovered that artificial induction of GluCer accumulation leads to cellular senescence of DA neurons, suggesting that lipid aggregation plays a crucial role in the pathology of PD by driving senescence in these vulnerable DA neurons. Here, we discuss the relevance of the age-related aggregation of lipids as well as the direct functional link between general lipid aggregation, cellular senescence, and inflammaging of DA neurons. We propose that the expression of a cellular senescence phenotype in the most vulnerable neurons in PD can be triggered by lysosomal impairment and lipid aggregation. Importantly, we highlight additional data that perilipin (PLIN2) is significantly upregulated in senescent DA neurons, suggesting an overall enrichment of lipid droplets (LDs) in these cells. These findings align with our previous results in dopaminergic neurons in highlighting a central role for lipid accumulation in the senescence of DA neurons. Importantly, general lipid droplet aggregation and global lysosomal impairment have been implicated in many neurodegenerative diseases including PD. Taken together, our data suggest a connection between age-related lysosomal impairment, lipid accumulation, and cellular senescence in DA neurons that in turn drives inflammaging in the midbrain and ultimately leads to neurodegeneration and PD.
    Keywords:  Parkinson’s disease; cellular senescence; glucosylceramides; lipids; lysosomes; neuroinflammation
    DOI:  https://doi.org/10.18632/aging.206030
  26. Proc Natl Acad Sci U S A. 2024 Jul 30. 121(31): e2407546121
    Early metformin treatment: An effective approach for targeting fragile X syndrome pathophysiology.
    Jung-Hyun Choi, Laura Marsal-García, Eve Peraldi, Caleb Walters, Ziying Huang, Ilse Gantois, Nahum Sonenberg.
      Fragile X syndrome (FXS) is the most common genetic cause of autism spectrum disorder engendered by transcriptional silencing of the fragile X messenger ribonucleoprotein 1 (FMR1) gene. Given the early onset of behavioral and molecular changes, it is imperative to know the optimal timing for therapeutic intervention. Case reports documented benefits of metformin treatment in FXS children between 2 and 14 y old. In this study, we administered metformin from birth to Fmr1-/y mice which corrected up-regulated mitogen-2 activated protein kinase/extracellular signal-regulated kinase and mammalian/mechanistic target of rapamycin complex 1 signaling pathways and specific synaptic mRNA-binding targets of FMRP. Metformin rescued increased number of calls in ultrasonic vocalization and repetitive behavior in Fmr1-/y mice. Our findings demonstrate that in mice, early-in-life metformin intervention is effective in treating FXS pathophysiology.
    Keywords:  Fmr1 KO mouse model; autism spectrum disorder; fragile X syndrome; mTORC1 and ERK signaling pathways; metformin
    DOI:  https://doi.org/10.1073/pnas.2407546121
  27. Chem Biol Interact. 2024 Jul 19. pii: S0009-2797(24)00304-1. [Epub ahead of print]400 111158
    Autophagy aggravates multi-walled carbon nanotube-induced ferroptosis by suppressing PGC-1 dependent-mitochondrial biogenesis in lung epithelial cells.
    Lin Zhu, Deyu Zhu, Jiahui Ran, Maojie Li, Zhebin Lai, Yan Zhou, Lei Luo, Xiliang Liu, Kanmin Mao, Kunming Tian.
      Multi-walled carbon nanotube (MWCNT) induced respiratory toxicity has become a growing concern, with ferroptosis emerging as a novel mechanism implicated in various respiratory diseases. However, whether ferroptosis is involved in MWCNT-elicited lung injury and the underlying molecular mechanisms warrant further exploration. In this study, we found that MWCNT-induced ferroptosis is autophagy-dependent, contributing to its cellular toxicity. Inhibiting of autophagy by pharmacological inhibitors 3-MA or ATG5 gene knockdown significantly attenuated MWCNT-induced ferroptosis, concomitant with rescued mitochondrial biogenesis. Rapamycin, the autophagy agonist, exacerbated the mitochondrial damage and MWCNT-induced ferroptosis. Moreover, lentivirus-mediated overexpression of PGC-1α inhibited ferroptosis, while inhibition of PGC-1α aggravated ferroptosis. In summary, our study unveils ferroptosis as a novel mechanism underlying MWCNT-induced respiratory toxicity, with autophagy promoting MWCNT-induced ferroptosis by hindering PGC-1α-dependent mitochondrial biogenesis.
    Keywords:  Autophagy; BEAS-2B cells; Ferroptosis; Mitochondria biogenesis; Multi-walled carbon nanotube
    DOI:  https://doi.org/10.1016/j.cbi.2024.111158
  28. Methods Mol Biol. 2024 Jul 25.
    Assessment of Non-canonical Functions of the Autophagy Proteins in LC3-Associated Phagocytosis and LC3-Associated Endocytosis.
    Luigi Mari, Emilio Boada-Romero, Zhenrui Li, Joelle Magné, Douglas R Green.
      The identification and characterization of noncanonical functions within the autophagy pathway have unveiled intricate cellular processes, including LC3-associated phagocytosis (LAP) and LC3-associated endocytosis (LANDO). These phenomena play pivotal roles in the conjugation of ATG8 with single-membrane phagosomes and endosomes, shedding light on the dynamic interplay between autophagy and cellular homeostasis. Here, we present detailed protocols for both qualitative and quantitative assessment of LAP, including immunofluorescence, flow cytometry, and Western blotting of isolated LAPosomes. Additionally, the protocol for the evaluation of LANDO through immunofluorescent detection of receptor recycling is outlined. The methodologies presented herein serve as a practical guide for researchers seeking to unravel the intricacies of LAP and LANDO. By providing step-by-step instructions, accompanied by insights into potential challenges and optimization strategies, this chapter aims to empower investigators in the exploration of these noncanonical functions of autophagy proteins.
    Keywords:  ATG8; Autophagy; Flow cytometry; Immunofluorescence; LANDO; LAP; LC3-associated endocytosis; LC3-associated phagocytosis; Phagosome; Receptor recycling; Western blotting
    DOI:  https://doi.org/10.1007/7651_2024_561
  29. J Neurosci. 2024 Jul 25. pii: e0879242024. [Epub ahead of print]
    ALS-linked VapB P56S mutation alters neuronal mitochondrial turnover at the synapse.
    Hiu-Tung C Wong, Angelica E Lang, Chris Stein, Catherine M Drerup.
      Mitochondrial population maintenance in neurons is essential for neuron function and survival. Contact sites between mitochondria and the endoplasmic reticulum (ER) are poised to regulate mitochondrial homeostasis in neurons. These contact sites can function to facilitate transfer of calcium and lipids between the organelles and have been shown to regulate aspects of mitochondrial fission and fusion dynamics. VapB is an ER membrane protein present at a subset of ER-mitochondria contact sites. Mutations in VapB cause neurodegenerative disease. Specifically, a proline-to-serine mutation at amino acid 56 (P56S), correlates with susceptibility to amyotrophic lateral sclerosis (ALS) type 8. Given the relationship between failed mitochondrial health and neurodegenerative disease, we investigated the function of VapB in mitochondrial population maintenance. We demonstrate that transgenic expression of VapBP56S in zebrafish larvae (sex undetermined) increased mitochondrial biogenesis, causing increased mitochondrial population size in the axon terminal. Expression of wild type VapB did not alter biogenesis but, instead, increased mitophagy in the axon terminal. Using genetic manipulations to independently increase mitochondrial biogenesis in zebrafish neurons, we show that biogenesis is normally balanced by mitophagy to maintain a constant mitochondrial population size. VapBP56S transgenics fail to increase mitophagy to compensate for the increase in mitochondrial biogenesis, suggesting an impaired mitophagic response. Finally, using a synthetic ER-mitochondria tether, we show that VapB's function in mitochondrial turnover is likely independent of ER-mitochondrial tethering by contact sites. Our findings demonstrate that VapB can control mitochondrial turnover in the axon terminal, and this function is altered by the P56S ALS-linked mutation.Significance statement Mitochondrial population dysfunction is tightly tied to neurodegenerative diseases, including ALS. Maintenance of the mitochondrial population in neurons requires the birth of new mitochondria and the degradation of damaged organelles. ER-mitochondrial contact site proteins are in a position to regulate both processes in neurons. Our work demonstrates that an ALS-associated mutation in the contact site protein VapB disrupts both processes, identifying VapB as a mediator of regulated mitochondrial turnover to maintain a steady-state mitochondrial population.
    DOI:  https://doi.org/10.1523/JNEUROSCI.0879-24.2024
  30. Semin Immunopathol. 2024 Jul 23. 46(3-4): 6
    The role of galectins in the regulation of autophagy and inflammasome in host immunity.
    Tzu-Han Lo, I-Chun Weng, Hung-Lin Chen, Fu-Tong Liu.
      Galectins, a family of glycan-binding proteins have been shown to bind a wide range of glycans. In the cytoplasm, these glycans can be endogenous (or "self"), originating from damaged endocytic vesicles, or exogenous (or "non-self"), found on the surface of invading microbial pathogens. Galectins can detect these unusual cytosolic exposures to glycans and serve as critical regulators in orchestrating immune responses in innate and adaptive immunity. This review provides an overview of how galectins modulate host cellular responses, such as autophagy, xenophagy, and inflammasome-dependent cell death program, to infection.
    Keywords:  Autophagy; Galectins; Glycans; Infection; Inflammasome
    DOI:  https://doi.org/10.1007/s00281-024-01018-5
  31. Life Sci. 2024 Jul 19. pii: S0024-3205(24)00508-3. [Epub ahead of print]353 122918
    Nitidine chloride inhibits mTORC1 signaling through ATF4-mediated Sestrin2 induction and targets IGF2R for lysosomal degradation.
    Fengzhi Chen, Shujun Peng, Canrong Li, Fan Yang, Yuguo Yi, Xinyu Chen, Haolun Xu, Baicheng Cheng, Yumin Xu, Xiaoduo Xie.
       AIMS: Nitidine chloride (NC), a natural phytochemical alkaloid derived from Zanthoxylum nitidum (Roxb.) DC, exhibits multiple bioactivities, including antitumor, anti-inflammatory, and other therapeutic effects. However, the primary targets of NC and the mechanism of action (MOA) have not been explicitly defined.
    METHODS: We explored the effects of NC on mTORC1 signaling by immunoblotting and fluorescence microscopy in wild-type and gene knockout cell lines generated by the CRISPR/Cas9 gene editing technique. We identified IGF2R as a direct target of NC via the drug affinity-responsive target stability (DARTS) method. We investigated the antitumor effects of NC using a mouse melanoma B16 tumor xenograft model.
    KEY FINDINGS: NC inhibits mTORC1 activity by targeting amino acid-sensing signaling through activating transcription factor 4 (ATF4)-mediated Sestrin2 induction. NC directly binds to IGF2R and promotes its lysosomal degradation. Moreover, NC displayed potent cytotoxicity against various cancer cells and inhibited B16 tumor xenografts.
    SIGNIFICANCE: NC inhibits mTORC1 signaling through nutrient sensing and directly targets IGF2R for lysosomal degradation, providing mechanistic insights into the MOA of NC.
    Keywords:  ATF4; B16 melanoma; IGF2R; Nitidine chloride; SESTRIN2; mTORC1
    DOI:  https://doi.org/10.1016/j.lfs.2024.122918
  32. Cancer Res. 2024 Jul 23.
    Arginine methylation of DDX3 by PRMT1 mediates mitochondrial homeostasis to promote breast cancer metastasis.
    Wen-Jing Hsu, Ming-Chen Chiang, Yi-Chun Chao, Yu-Chu Chang, Ming-Chien Hsu, Chu-Hung Chung, I-Lin Tsai, Cheng-Ying Chu, Han-Chung Wu, Ching-Chieh Yang, Chi-Ching Lee, Cheng-Wei Lin.
      Dysregulated mitochondrial dynamics and metabolism play important roles in tumorigenesis. Metastasizing tumor cells predominantly utilize mitochondrial metabolism, and regulators of metabolic reprogramming may provide reliable biomarkers for diagnosing cancer metastasis. Here, we identified a PRMT1-DDX3 axis that promotes breast cancer metastasis by coordinating mitochondrial biogenesis and mitophagy to ensure mitochondrial quality control. Mechanistically, PRMT1 induces arginine methylation of DDX3, which enhances its protein stability and prevents proteasomal degradation. DDX3 mediates mitochondrial homeostasis by translocating to mitochondria where it facilitates PINK1 translation in response to mitochondrial stress. Inhibition of DDX3 suppresses mitochondrial biogenesis and mitophagy, resulting in diminished cancer stemness and metastatic properties. Overall, this study uncovers a mechanism by which the PRMT1-DDX3 axis regulates mitochondrial homeostasis to support breast cancer metastasis, suggesting strategies for targeting metabolic vulnerabilities to treat metastatic breast cancer.
    DOI:  https://doi.org/10.1158/0008-5472.CAN-23-3829
  33. Autophagy. 2024 Jul 26. 1-17
    GORASP2 promotes phagophore closure and autophagosome maturation into autolysosomes.
    Yusheng Xing, Lei Huang, Yannan Jian, Zhenqian Zhang, Xiaodan Zhao, Xing Zhang, Tingting Fu, Yue Zhang, Yijie Wang, Xiaoyan Zhang.
      As the central hub of the secretory pathway, the Golgi apparatus plays a crucial role in maintaining cellular homeostasis in response to stresses. Recent studies have revealed the involvement of the Golgi tether, GORASP2, in facilitating autophagosome-lysosome fusion by connecting LC3-II and LAMP2 during nutrient starvation. However, the precise mechanism remains elusive. In this study, utilizing super-resolution microscopy, we observed GORASP2 localization on the surface of autophagosomes during glucose starvation. Depletion of GORASP2 hindered phagophore closure by regulating the association between VPS4A and the ESCRT-III component, CHMP2A. Furthermore, we found that GORASP2 controls RAB7A activity by modulating its GEF complex, MON1A-CCZ1, thereby impacting RAB7A's interaction with the HOPS complex. The assembly of both STX17-SNAP29-VAMP8 and YKT6-SNAP29-STX7 SNARE complexes was also attenuated without GORASP2. These findings suggest that GORASP2 helps seal autophagosomes and activate the RAB7A-HOPS-SNAREs membrane fusion machinery for autophagosome maturation, highlighting its membrane tethering function in response to stresses.Abbreviations: BafA1: bafilomycin A1; ESCRT: endosomal sorting complex required for transport; FPP: fluorescence protease protection; GEF: guanine nucleotide exchange factor; GFP: green fluorescent protein; GORASP2: golgi reassembly stacking protein 2; GSB: glucose starvation along with bafilomycin A1; HOPS: homotypic fusion and protein sorting; LAMP2: lysosomal associated membrane protein 2; MAP1LC3B: microtubule associated protein 1 light chain 3 beta; PBS: phosphate-buffered saline; PtdIns3K: phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol-3-phosphate; PK: proteinase K; SNARE: soluble N-ethylmaleimide-sensitive factor attachment protein receptor; SIM: structured illumination microscopy; UVRAG: UV radiation resistance associated.
    Keywords:  Autophagosome maturation; ESCRT complex; GORASP2; RAB7A; SNAREs; phagophore closure
    DOI:  https://doi.org/10.1080/15548627.2024.2375785
  34. Biochem Biophys Res Commun. 2024 Jul 18. pii: S0006-291X(24)00958-6. [Epub ahead of print]732 150422
    ATM facilitates autophagy and protects against oxidative stress and apoptosis in response to ER stress in vitro.
    Danélle Bester, Marguerite Blignaut, Barbara Huisamen.
      The endoplasmic reticulum (ER) responds to cellular stress by initiating an unfolded protein response (UPR) that mitigates misfolded protein accumulation by promoting protein degradation pathways. Chronic ER stress leads to UPR-mediated apoptosis and is a common underlying feature of various diseases, highlighting the modulators of the UPR as attractive targets for therapeutic intervention. Ataxia-telangiectasia mutated protein kinase (ATM) is a stress-responsive kinase that initiates autophagy in response to reactive oxygen species (ROS), and ATM deficiency is associated with increased ER stress markers in vitro. However, whether ATM participates in the UPR remains unclear. In this in vitro study, a novel role for ATM in the ER stress response is described using the well-characterized HEK293 cells treated with the common ER stress-inducing agent, tunicamycin, with and without the potent ATM inhibitor, KU-60019. We show for the first time that ATM is activated in a time-dependent manner downstream of UPR initiation in response to tunicamycin treatment. Furthermore, we demonstrate that ATM is required for p62-bound protein cargo degradation through the autophagy pathway in response to ER stress. Lastly, our data suggest a protective role for ATM in ER stress-mediated oxidative stress and mitochondrial apoptosis. Taken together, we highlight ATM as a potential novel drug target in ER stress-related diseases.
    Keywords:  ATM; Apoptosis; Autophagy; ER stress; Oxidative stress; UPR
    DOI:  https://doi.org/10.1016/j.bbrc.2024.150422
  35. J Alzheimers Dis. 2024 Jul 15.
    Mutant NOTCH3ECD Triggers Defects in Mitochondrial Function and Mitophagy in CADASIL Cell Models.
    Wan Wang, Zhenping Gong, Yadan Wang, Ying Zhao, Yaru Lu, Ruihua Sun, Haohan Zhang, Junkui Shang, Jiewen Zhang.
       Background: Cerebral autosomal-dominant arteriopathy with subcortical infarction and leukoencephalopathy (CADASIL) is an inherited small-vessel disease that affects the white matter of the brain. Recent studies have confirmed that the deposition of NOTCH3ECD is the main pathological basis of CADASIL; however, whether different mutations present the same pathological characteristics remains to be further studied. Some studies have found that mitochondrial dysfunction is related to CADASIL; however, the specific effects of NOTCH3ECD on mitochondrial remain to be determined.
    Objective: We aimed to explore the role of mitochondrial dysfunction in CADASIL.
    Methods: We established transgenic human embryonic kidney-293T cell models (involving alterations in cysteine and non-cysteine residues) via lentiviral transfection. Mitochondrial function and structure were assessed using flow cytometry and transmission electron microscopy, respectively. Mitophagy was assessed using western blotting and immunofluorescence.
    Results: We demonstrated that NOTCH3ECD deposition affects mitochondrial morphology and function, and that its protein levels are significantly correlated with mitochondrial quality and can directly bind to mitochondria. Moreover, NOTCH3ECD deposition promoted the induction of autophagy and mitophagy. However, these processes were impaired, leading to abnormal mitochondrial accumulation.
    Conclusions: This study revealed a common pathological feature of NOTCH3ECD deposition caused by different NOTCH3 mutations and provided new insights into the role of NOTCH3ECD in mitochondrial dysfunction and mitophagy.
    Keywords:  Alzheimer’s disease; CADASIL; NOTCH3ECD mutation; autophagy; mitochondrial dysfunction; mitophagy
    DOI:  https://doi.org/10.3233/JAD-240273
  36. J Biol Chem. 2024 Jul 24. pii: S0021-9258(24)02102-1. [Epub ahead of print] 107601
    CYYR1 promotes the degradation of the E3 ubiquitin ligase WWP1 and is associated with favorable prognosis in breast cancer.
    Tiphaine Perron, Mathieu Boissan, Ivan Bièche, Laura Courtois, Florent Dingli, Damarys Loew, Mouna Chouchène, Sabrina Colasse, Laurence Levy, Céline Prunier.
      Ubiquitination plays a crucial role in cellular homeostasis by regulating the degradation, localization, and activity of proteins, ensuring proper cell function and balance. Among E3 ubiquitin ligases, WWP1 is implicated in cell proliferation, survival and apoptosis. Notably WWP1 is frequently amplified in breast cancer and associated with poor prognosis. Here we identify the protein CYYR1 that had previously no assigned function, as a regulator of WWP1 activity and stability. We show that CYYR1 binds to the WW domains of the E3 ubiquitin ligase WWP1 through its PPxY motifs. This interaction triggers K63-linked auto-ubiquitination and subsequent degradation of WWP1. We furthermore demonstrate that CYYR1 localizes to late endosomal vesicles and directs poly-ubiquitinated WWP1 toward lysosomal degradation through binding to ANKRD13A. Moreover, we found that CYYR1 expression attenuates breast cancer cell growth in anchorage-dependent and independent colony formation assays in a PPxY-dependent manner. Finally, we highlight that CYYR1 expression is significantly decreased in breast cancer and is associated with beneficial clinical outcome. Taken together our study suggests tumor suppressor properties for CYYR1 through regulation of WWP1 auto-ubiquitination and lysosomal degradation.
    Keywords:  CYYR1; E3 ubiquitin ligase; WWP1; breast cancer; ubiquitination
    DOI:  https://doi.org/10.1016/j.jbc.2024.107601
  37. Adv Sci (Weinh). 2024 Jun 21. e2400952
    The Toxoplasma Effector GRA4 Hijacks Host TBK1 to Oppositely Regulate Anti-T. Gondii Immunity and Tumor Immunotherapy.
    Zhiqiang Hu, Yufen Zhang, Yingchao Xie, Jianwu Yang, Haotian Tang, Bolin Fan, Ke Zeng, Zhongxin Han, Jiansen Lu, Huaji Jiang, Wenqiang Peng, Hongyu Li, Huadan Chen, Sha Wu, Bang Shen, Zhao-Rong Lun, Xiao Yu.
      Toxoplasma gondii (T. gondii)-associated polymorphic effector proteins are crucial in parasite development and regulating host anti-T. gondii immune responses. However, the mechanism remains obscure. Here, it is shown that Toxoplasma effector dense granules 4 (GRA4) restricts host IFN-I activation. Infection with Δgra4 mutant T. gondii strain induces stronger IFN-I responses and poses a severe threat to host health. Mechanistically, GRA4 binds to phosphorylated TBK1 to promote TRIM27-catalyzed K48-ubiquitination at Lys251/Lys372 residues, which enhances its recognition by autophagy receptor p62, ultimately leading to TBK1 autophagic degradation. Furthermore, an avirulent Δgra4 strain (ME49Δompdc/gra4) is constructed for tumor immunotherapy due to its ability to enhance IFN-I production. Earlier vaccination with ME49Δompdc/gra4 confers complete host resistance to the tumor compared with the classical ME49Δompdc treatment. Notably, ME49Δompdc/gra4 vaccination induces a specific CD64+MAR-1+CD11b+ dendritic cell subset, thereby enhancing T cell anti-tumor responses. Overall, these findings identify the negative role of T. gondii GRA4 in modulating host IFN-I signaling and suggest that GRA4 can be a potential target for the development of T. gondii vaccines and tumor immunotherapy.
    Keywords:  attenuated T. gondii; selective autophagy; toxoplasmosis; tumor therapy; type I interferon
    DOI:  https://doi.org/10.1002/advs.202400952
  38. Eur J Med Chem. 2024 Jul 17. pii: S0223-5234(24)00568-3. [Epub ahead of print]276 116688
    Autophagy modulation in cancer therapy: Challenges coexist with opportunities.
    Yongya Wu, Aoxue Wang, Guotai Feng, Xiaoli Pan, Wen Shuai, Panpan Yang, Jing Zhang, Liang Ouyang, Yi Luo, Guan Wang.
      Autophagy, a crucial intracellular degradation process facilitated by lysosomes, plays a pivotal role in maintaining cellular homeostasis. The elucidation of autophagy key genes and signaling pathways has significantly advanced our understanding of this process and has led to the exploration of autophagy as a promising therapeutic approach. This review comprehensively assesses the latest developments in small molecule modulators targeting autophagy. Moreover, the review delves into the most recent strategies for drug discovery, specifically focusing on selective agents that exploit autophagosomes and lysosomes for targeted protein degradation. Additionally, this article highlights the prevailing challenges and outlines potential future advancements in the field. By amalgamating the cutting-edge knowledge in the field, we aim to offer valuable insights and references for the anti-cancer drug development of autophagy-targeted therapies, thus contributing to the advancement of novel therapeutic interventions.
    Keywords:  Autophagy; Drug targets; Malignancy treatment; Signaling pathways; Small molecule modulators
    DOI:  https://doi.org/10.1016/j.ejmech.2024.116688
  39. EMBO J. 2024 Jul 23.
    Connexin43 promotes exocytosis of damaged lysosomes through actin remodelling.
    Neuza Domingues, Steve Catarino, Beatriz Cristóvão, Lisa Rodrigues, Filomena A Carvalho, Maria João Sarmento, Mónica Zuzarte, Jani Almeida, Teresa Ribeiro-Rodrigues, Ânia Correia-Rodrigues, Fábio Fernandes, Paulo Rodrigues-Santos, Trond Aasen, Nuno C Santos, Viktor I Korolchuk, Teresa Gonçalves, Ira Milosevic, Nuno Raimundo, Henrique Girão.
      A robust and efficient cellular response to lysosomal membrane damage prevents leakage from the lysosome lumen into the cytoplasm. This response is understood to happen through either lysosomal membrane repair or lysophagy. Here we report exocytosis as a third response mechanism to lysosomal damage, which is further potentiated when membrane repair or lysosomal degradation mechanisms are impaired. We show that Connexin43 (Cx43), a protein canonically associated with gap junctions, is recruited from the plasma membrane to damaged lysosomes, promoting their secretion and accelerating cell recovery. The effects of Cx43 on lysosome exocytosis are mediated by a reorganization of the actin cytoskeleton that increases plasma membrane fluidity and decreases cell stiffness. Furthermore, we demonstrate that Cx43 interacts with the actin nucleator Arp2, the activity of which was shown to be necessary for Cx43-mediated actin rearrangement and lysosomal exocytosis following damage. These results define a novel mechanism of lysosomal quality control whereby Cx43-mediated actin remodelling potentiates the secretion of damaged lysosomes.
    Keywords:  Actin-remodelling; Arp2; Connexin43; Exocytosis; Lysosomal Damage
    DOI:  https://doi.org/10.1038/s44318-024-00177-3
  40. J Lipid Res. 2024 Jul 18. pii: S0022-2275(24)00103-2. [Epub ahead of print] 100598
    All-trans retinoic acid induces lipophagy through reducing Rubicon in Hepa1c1c7 cells.
    Anh The Nguyen, Masashi Masuda, Yuki Mori, Yuichiro Adachi, Teppei Fukuda, Airi Furuichi, Masaki Takikawa, Yuki Tsuda, Yuki Hamada, Yusuke Maruyama, Hirokazu Ohminami, Kohta Ohnishi, Yutaka Taketani.
      All-trans retinoic acid (atRA), a metabolite of vitamin A, reduces hepatic lipid accumulation in liver steatosis model animals. Lipophagy, a new lipolysis pathway, degrades a lipid droplet (LD) via autophagy in adipose tissue and the liver. We recently found that atRA induces lipophagy in adipocytes. However, it remains unclear whether atRA induces lipophagy in hepatocytes. In this study, we investigated the effects of atRA on lipophagy in Hepa1c1c7 cells and the liver of mice fed a high-fat diet (HFD). Firstly, we confirmed that atRA induced autophagy in Hepa1c1c7 cells by Western blotting and the GFP-LC3-mCherry probe. Next, we evaluated the lipolysis in fatty Hepa1c1c7 cells treated with the knockdown of Atg5, an essential gene in autophagy induction. Atg5-knockdown partly suppressed the atRA-induced lipolysis in fatty Hepa1c1c7 cells. We also found that atRA reduced the protein, but not mRNA, expression of Rubicon, a negative regulator of autophagy, in Hepa1c1c7 cells and the liver of HFD-fed mice. Rubicon-knockdown partly inhibited the atRA-induced lipolysis in fatty Hepa1c1c7 cells. In addition, atRA reduced hepatic Rubicon expression in young mice, but the effect of atRA on it diminished in aged mice. Lastly, we investigated the mechanism underlying reduced Rubicon protein expression by atRA in hepatocytes. A protein synthesis inhibitor, but not proteasome or lysosomal inhibitors, significantly blocked the reduction of Rubicon protein expression by atRA in Hepa1c1c7 cells. These results suggest that atRA may promote lipophagy in fatty hepatocytes by reducing hepatic Rubicon expression via inhibiting protein synthesis. (243/250 words).
    Keywords:  Lipid droplets; Lipolysis and fatty acid metabolism; Liver; Nutrition; Vitamin A
    DOI:  https://doi.org/10.1016/j.jlr.2024.100598
  41. J Biol Chem. 2024 Jul 24. pii: S0021-9258(24)02106-9. [Epub ahead of print] 107605
    Structural basis for TNIP1 binding to FIP200 during mitophagy.
    Shengmei Wu, Mingwei Li, Lei Wang, Lingna Yang, Jing Cui, Fudong Li, Qian Wang, Yunyu Shi, Mengqi Lv.
      TNIP1 has been increasingly recognized as a security check to finely adjust the rate of mitophagy by disrupting the recycling of the Unc-51-like kinase (ULK) complex during autophagosome formation. Through tank-binding kinase 1 (TBK1)-mediated phosphorylation of the TNIP1 FIR motif, the binding affinity of TNIP1 for FIP200, a component of the ULK complex, is enhanced, allowing TNIP1 to outcompete autophagy receptors. Consequently, FIP200 is released from the autophagosome, facilitating further autophagosome expansion. However, the molecular basis by which FIP200 utilizes its claw domain to distinguish the phosphorylation status of residues in the TNIP1 FIP200 interacting region (FIR) motif for recognition is not well understood. Here, we elucidated multiple crystal structures of the complex formed by the FIP200 claw domain and various phosphorylated TNIP1 FIR peptides. Structural and isothermal titration calorimetry (ITC) analyses identified the crucial residues in the FIP200 claw domain responsible for the specific recognition of phosphorylated TNIP1 FIR peptides. Additionally, utilizing structural comparison and molecular dynamics (MD) simulation data, we demonstrated that the C-terminal tail of TNIP1 peptide affected its binding to the FIP200 claw domain. Moreover, the phosphorylation of TNIP1 Ser123 enabled the peptide to effectively compete with the peptide p-CCPG1 (the FIR motif of the autophagy receptor CCPG1) for binding with the FIP200 claw domain. Overall, our work provides a comprehensive understanding of the specific recognition of phosphorylated TNIP1 by the FIP200 claw domain, marking an initial step toward fully understanding the molecular mechanism underlying the TNIP1-dependent inhibition of mitophagy.
    Keywords:  TNFAIP3-interacting protein 1 (TNIP1); crystal structure; focal adhesion kinase (FAK)-interacting protein of 200 kDa (FIP200); mitophagy; phosphorylation
    DOI:  https://doi.org/10.1016/j.jbc.2024.107605
  42. Cell Biochem Funct. 2024 Jul;42(5): e4101
    Cellular response during cellular starvation: A battle for cellular survivability.
    Tithi Bhowmick, Souradeep Biswas, Avinaba Mukherjee.
      Cellular starvation occurs when a cell is deprived of nutrition and oxygen availability. The genesis of this state of deprivation is exclusively contingent upon the inadequacy in the supply of essential components, namely amino acids, glucose, and oxygen. Consequently, the impact of this altered condition manifests in the regulation of cellular respiratory, metabolic, and stress responses. Subsequently, as a reactive outcome, cell death may transpire through mechanisms such as autophagy or apoptosis, particularly under prolonged circumstances. However, the cell combats such situations by evolving altered activity in their metabolic and protein level. Modulated signaling cascades help them to conquer starvation. But as in a prolonged condition, the battle that a cell has to evolve will come into and result in the form of cellular death. Therefore, in cancer therapy, cellular starvation may also act as a possible way out so that the cancer cell can undergo its death pathway in an induced starved condition. This review has collectively depicted the mechanism of cellular starvation. Besides this, the cellular response in this starved condition has also been summarized. Gaining such knowledge of the causation of cell starvation and cellular response during starvation not only generates new insight into the mechanism of cell survivability but also may act as a beneficial role in combating cellular diseases like cancer.
    Keywords:  cell death; cell starvation; cellular survivability; hypoxia; metabolism
    DOI:  https://doi.org/10.1002/cbf.4101
  43. Mol Neurodegener. 2024 Jul 23. 19(1): 55
    Astrocytic autophagy plasticity modulates Aβ clearance and cognitive function in Alzheimer's disease.
    Suhyun Kim, Heejung Chun, Yunha Kim, Yeyun Kim, Uiyeol Park, Jiyeon Chu, Mridula Bhalla, Seung-Hye Choi, Ali Yousefian-Jazi, Sojung Kim, Seung Jae Hyeon, Seungchan Kim, Yeonseo Kim, Yeon Ha Ju, Seung Eun Lee, Hyunbeom Lee, Kyungeun Lee, Soo-Jin Oh, Eun Mi Hwang, Junghee Lee, C Justin Lee, Hoon Ryu.
       BACKGROUND: Astrocytes, one of the most resilient cells in the brain, transform into reactive astrocytes in response to toxic proteins such as amyloid beta (Aβ) in Alzheimer's disease (AD). However, reactive astrocyte-mediated non-cell autonomous neuropathological mechanism is not fully understood yet. We aimed our study to find out whether Aβ-induced proteotoxic stress affects the expression of autophagy genes and the modulation of autophagic flux in astrocytes, and if yes, how Aβ-induced autophagy-associated genes are involved Aβ clearance in astrocytes of animal model of AD.
    METHODS: Whole RNA sequencing (RNA-seq) was performed to detect gene expression patterns in Aβ-treated human astrocytes in a time-dependent manner. To verify the role of astrocytic autophagy in an AD mouse model, we developed AAVs expressing shRNAs for MAP1LC3B/LC3B (LC3B) and Sequestosome1 (SQSTM1) based on AAV-R-CREon vector, which is a Cre recombinase-dependent gene-silencing system. Also, the effect of astrocyte-specific overexpression of LC3B on the neuropathology in AD (APP/PS1) mice was determined. Neuropathological alterations of AD mice with astrocytic autophagy dysfunction were observed by confocal microscopy and transmission electron microscope (TEM). Behavioral changes of mice were examined through novel object recognition test (NOR) and novel object place recognition test (NOPR).
    RESULTS: Here, we show that astrocytes, unlike neurons, undergo plastic changes in autophagic processes to remove Aβ. Aβ transiently induces expression of LC3B gene and turns on a prolonged transcription of SQSTM1 gene. The Aβ-induced astrocytic autophagy accelerates urea cycle and putrescine degradation pathway. Pharmacological inhibition of autophagy exacerbates mitochondrial dysfunction and oxidative stress in astrocytes. Astrocyte-specific knockdown of LC3B and SQSTM1 significantly increases Aβ plaque formation and GFAP-positive astrocytes in APP/PS1 mice, along with a significant reduction of neuronal marker and cognitive function. In contrast, astrocyte-specific overexpression of LC3B reduced Aβ aggregates in the brain of APP/PS1 mice. An increase of LC3B and SQSTM1 protein is found in astrocytes of the hippocampus in AD patients.
    CONCLUSIONS: Taken together, our data indicates that Aβ-induced astrocytic autophagic plasticity is an important cellular event to modulate Aβ clearance and maintain cognitive function in AD mice.
    Keywords:  Alzheimer’s disease; Amyloid beta (Aβ); Astrocytes; Autophagy; Aβ clearance; Mitochondria
    DOI:  https://doi.org/10.1186/s13024-024-00740-w
  44. Chem Asian J. 2024 Jul 25. e202400600
    Diphenylbutadiene Fluorescent Analogues in Sub-cellular Imaging and Monitoring Mitophagy.
    Mohini Ghorpade, Abdulkhalik Mansuri, Ashutosh Kumar, Sriram Kanvah.
      A series of donor-acceptor (D-π-A) substituted diphenylbutadienes exhibiting solvatochromic emission and a large Stokes shift (100-200 nm) were designed and synthesized for distinctive organelle labelling, enabling real-time monitoring of organelle behaviour such as lysosomal dynamics, mitophagy monitoring, and stress responses. The morpholine-substituted D-A-D diphenylbutadiene (M2) was employed to investigate selective imaging of lysosomes, the uptake of damaged mitochondria through mitophagy, and monitoring lysosomal viscosity or pH changes. Other diphenylbutadiene derivatives (M1, M3, M4) selectively accumulated in lipid droplets. All the synthesized derivatives demonstrated significant uptake in 5-day post-fertilization zebrafish larvae, with M2 showing maximum uptake in the enterocyte-containing heart and intestinal regions, which include the lysosomes.
    Keywords:  Fluorescence Microscopy; Live-Cell Imaging; Mitophagy; Zebrafish; diarylbutadienes
    DOI:  https://doi.org/10.1002/asia.202400600
  45. Int J Mol Sci. 2024 Jul 18. pii: 7889. [Epub ahead of print]25(14):
    O-Sialoglycoprotein Endopeptidase Deficiency Impairs Proteostasis and Induces Autophagy in Human Embryonic Stem Cells.
    Hua Teng, Siyi Chen, Fang Liu, Yanling Teng, Yunlong Li, Desheng Liang, Lingqian Wu, Zhuo Li.
      The OSGEP gene encodes O-sialoglycoprotein endopeptidase, a catalytic unit of the highly conserved KEOPS complex (Kinase, Endopeptidase, and Other Proteins of small Size) that regulates the second biosynthetic step in the formation of N-6-threonylcarbamoyladenosine (t6A). Mutations in KEOPS cause Galloway-Mowat syndrome (GAMOS), whose cellular function in mammals and underlying molecular mechanisms are not well understood. In this study, we utilized lentivirus-mediated OSGEP knockdown to generate OSGEP-deficient human embryonic stem cells (hESCs). OSGEP-knockdown hESCs exhibited reduced stemness factor expression and G2/M phase arrest, indicating a potential role of OSGEP in the regulation of hESC fate. Additionally, OSGEP silencing led to enhanced protein synthesis and increased aggregation of proteins, which further induced inappropriate autophagy, as evidenced by the altered expression of P62 and the conversion of LC3-I to LC3-II. The above findings shed light on the potential involvement of OSGEP in regulating pluripotency and differentiation in hESCs while simultaneously highlighting its crucial role in maintaining proteostasis and autophagy, which may have implications for human disease.
    Keywords:  OSGEP; hESCs; proteostasis; tRNA modification
    DOI:  https://doi.org/10.3390/ijms25147889
  46. Cells. 2024 Jul 12. pii: 1186. [Epub ahead of print]13(14):
    Advancements in Utilizing Natural Compounds for Modulating Autophagy in Liver Cancer: Molecular Mechanisms and Therapeutic Targets.
    Md Ataur Rahman, S M Rakib-Uz-Zaman, Somdeepa Chakraborti, Sujay Kumar Bhajan, Rajat Das Gupta, Maroua Jalouli, Md Anowar Khasru Parvez, Mushfiq H Shaikh, Ehsanul Hoque Apu, Abdel Halim Harrath, Seungjoon Moon, Bonglee Kim.
      Autophagy, an intrinsic catabolic mechanism that eliminates misfolded proteins, dysfunctional organelles, and lipid droplets, plays a vital function in energy balance and cytoplasmic quality control, in addition to maintaining cellular homeostasis. Liver cancer such as hepatocellular carcinoma (HCC) is one of the most common causes of cancer deaths globally and shows resistance to several anticancer drugs. Despite the rising incidence and poor prognosis of malignant HCC, the underlying molecular mechanisms driving this aggressive cancer remain unclear. Several natural compounds, such as phytochemicals of dietary and non-dietary origin, affect hepatocarcinogenesis signaling pathways in vitro and in vivo, which may help prevent and treat HCC cells. Current HCC cells treatments include chemotherapy, radiation, and surgery. However, these standard therapies have substantial side effects, and combination therapy enhances side effects for an acceptable therapeutic benefit. Therefore, there is a need to develop treatment strategies for HCC cells that are more efficacious and have fewer adverse effects. Multiple genetic and epigenetic factors are responsible for the HCC cells to become resistant to standard treatment. Autophagy contributes to maintain cellular homeostasis, which activates autophagy for biosynthesis and mitochondrial regulation and recycling. Therefore, modifying autophagic signaling would present a promising opportunity to identify novel therapies to treat HCC cells resistant to current standard treatments. This comprehensive review illustrates how natural compounds demonstrate their anti-hepatocellular carcinoma function through autophagy.
    Keywords:  autophagy; cancer therapy; hepatocellular carcinoma; homeostasis; natural compound
    DOI:  https://doi.org/10.3390/cells13141186
  47. Curr Opin Cell Biol. 2024 Jul 24. pii: S0955-0674(24)00081-4. [Epub ahead of print]90 102402
    Mechanisms of lipid droplet degradation.
    J H Corbo, J Chung.
      Lipid droplets (LDs) are subcellular organelles that play an integral role in lipid metabolism by regulating the storage and release of fatty acids, which are essential for energy production and various cellular processes. Lipolysis and lipophagy are the two major LD degradation pathways that mediate the utilization of lipids stored in these organelles. Recent studies have further uncovered alternative pathways, including direct lysosomal LD degradation and LD exocytosis. Here, we highlight recent findings that dissect the molecular basis of these diverse LD degradation pathways. Then, we discuss speculations on the crosstalk among these pathways and the potential unconventional roles of LD degradation.
    DOI:  https://doi.org/10.1016/j.ceb.2024.102402
  48. EMBO Rep. 2024 Jul 22.
    Fam134c and Fam134b shape axonal endoplasmic reticulum architecture in vivo.
    Francescopaolo Iavarone, Marta Zaninello, Michela Perrone, Mariagrazia Monaco, Esther Barth, Felix Gaedke, Maria Teresa Pizzo, Giorgia Di Lorenzo, Vincenzo Desiderio, Eduardo Sommella, Fabrizio Merciai, Emanuela Salviati, Pietro Campiglia, Livio Luongo, Elvira De Leonibus, Elena Rugarli, Carmine Settembre.
      Endoplasmic reticulum (ER) remodeling is vital for cellular organization. ER-phagy, a selective autophagy targeting ER, plays an important role in maintaining ER morphology and function. The FAM134 protein family, including FAM134A, FAM134B, and FAM134C, mediates ER-phagy. While FAM134B mutations are linked to hereditary sensory and autonomic neuropathy in humans, the physiological role of the other FAM134 proteins remains unknown. To address this, we investigate the roles of FAM134 proteins using single and combined knockouts (KOs) in mice. Single KOs in young mice show no major phenotypes; however, combined Fam134b and Fam134c deletion (Fam134b/cdKO), but not the combination including Fam134a deletion, leads to rapid neuromuscular and somatosensory degeneration, resulting in premature death. Fam134b/cdKO mice show rapid loss of motor and sensory axons in the peripheral nervous system. Long axons from Fam134b/cdKO mice exhibit expanded tubular ER with a transverse ladder-like appearance, whereas no obvious abnormalities are present in cortical ER. Our study unveils the critical roles of FAM134C and FAM134B in the formation of tubular ER network in axons of both motor and sensory neurons.
    Keywords:  Axon; Endoplasmic Reticulum; FAM134B; FAM134C
    DOI:  https://doi.org/10.1038/s44319-024-00213-7
  49. Brain Commun. 2024 ;6(4): fcae232
    Spatial selectivity of ATase inhibition in mouse models of Charcot-Marie-Tooth disease.
    Gonzalo Fernandez-Fuente, Mark A Farrugia, Yajing Peng, Andrew Schneider, John Svaren, Luigi Puglielli.
      The endoplasmic reticulum acetylation machinery has emerged as a new branch of the larger endoplasmic reticulum quality control system. It regulates the selection of correctly folded polypeptides as well as reticulophagy-mediated removal of toxic protein aggregates with the former being a particularly important aspect of the proteostatic functions of endoplasmic reticulum acetylation. Essential to this function is the Nε-lysine acetyltransferase activity of acetyltransferase 1 and acetyltransferase 2, which regulates the induction of endoplasmic reticulum-specific autophagy through the acetylation of the autophagy-related protein 9A. Here, we used three mouse models of Charcot-Marie-Tooth disease, peripheral myelin protein 22/Tr-J, C3-peripheral myelin protein 22 and myelin protein zero/ttrr, to study spatial and translational selectivity of endoplasmic reticulum acetyltransferase inhibitors. The results show that inhibition of the endoplasmic reticulum acetyltransferases selectively targets misfolding/pro-aggregating events occurring in the lumen of the organelle. Therefore, they establish acetyltransferase 1 and acetyltransferase 2 as the first proven targets for disease-causing proteotoxic states that initiate within the lumen of the endoplasmic reticulum/secretory pathway.
    Keywords:  ATase; Charcot–Marie–Tooth disease; acetylation; endoplasmic reticulum; proteostasis
    DOI:  https://doi.org/10.1093/braincomms/fcae232
  50. Reprod Biol Endocrinol. 2024 Jul 23. 22(1): 86
    Nur77 improves ovarian function in reproductive aging mice by activating mitophagy and inhibiting apoptosis.
    Ying Yao, Bin Wang, Kaihua Yu, Ji Song, Liyan Wang, Xuehong Zhang, Yulan Li.
      Reproductive aging not only affects the fertility and physical and mental health of women but also accelerates the aging process of other organs. There is an urgent need newfor novel mechanisms, targets, and drugs to break the vicious cycle of mitochondrial dysfunction, redox imbalance, and germ cell apoptosis associated with ovarian aging. Autophagy, recognized as a longevity mechanism, has recently become a focal point in anti-aging research. Although mitophagy is a type of autophagy, its role and regulatory mechanisms in ovarian aging, particularly in age-related ovarian function decline, remain unclear. Nerve growth factor inducible gene B (Nur77) is an early response gene that can be stimulated by oxidative stress, DNA damage, metabolism, and inflammation. Recent evidence recommends that decreased expression of Nur77 is associated with age-related myocardial fibrosis, renal dysfunction, and Parkinson's disease; however, its association with ovarian aging has not been studied yet. We herein identified Nur77 as a regulator of germ cell senescence, apoptosis, and mitophagy and found that overexpression of Nur77 can activate mitophagy, improve oxidative stress, reduce apoptosis, and ultimately enhance ovarian reserve in aged mice ovaries. Furthermore, we discovered an association between Nur77 and the AKT pathway through String and molecular docking analyses. Experimental confirmation revealed that the AKT/mTOR signaling pathway is involved in the regulation of Nur77 in ovarian function. In conclusion, our results suggest Nur77 as a promising target for preventing and treating ovarian function decline related to reproductive aging.
    Keywords:  Aging; Apoptosis; Granulosa cells; Mitophagy; Nur77; PINK1/Parkin
    DOI:  https://doi.org/10.1186/s12958-024-01250-6
  51. Curr Issues Mol Biol. 2024 Jul 16. 46(7): 7530-7547
    Erlotinib Treatment in Colorectal Cancer Suppresses Autophagy Based on KRAS Mutation.
    Alexander Siegman, Aaron Shaykevich, Danbee Chae, Isaac Silverman, Sanjay Goel, Radhashree Maitra.
      The KRAS gene is mutated in approximately 45% of colorectal cancer patients. There are currently very few targeted treatments or therapies equipped to directly inhibit KRAS due to its unusual structural intricacies. Erlotinib, an EGFR inhibitor, has previously been demonstrated to reduce cell viability by inducing autophagy in lung cancer cell lines with varying EGFR mutations. In contrast to lung cancer cells, evidence is provided herein for the first time that erlotinib treatment in colorectal cancer (CRC) cell lines reduces autophagy and still results in decreased cell viability. However, the effects of erlotinib in CRC cell lines containing a wildtype KRAS gene were different than in cells carrying a mutant KRAS gene. We show that there is significantly more downregulation of autophagy in KRAS mutant CRC cells compared to KRAS wildtype cells, both at transcriptional and translational levels, suggesting that the KRAS mutation is advantageous for cancer growth, even in the presence of erlotinib. Cell viability results determined that KRAS wildtype CRC cells had significantly more cell death compared to KRAS mutant cells. Using patient mRNA datasets, we showed that there was a significant correlation between the presence of the KRAS mutation and the expression of autophagy proteins. Additionally, through molecular dynamics simulations, we develop a blueprint for KRAS and autophagy protein interaction and the impact of the KRAS mutation on autophagy protein regulation. Overall, this is the first report of erlotinib treatment in CRC cells that assesses autophagy, and we demonstrate that autophagy activity is downregulated in these cells. This effect is not only greater in cells carrying a KRAS mutation compared to wildtype cells, but the KRAS mutant cells also have increased cell viability compared to wildtype cells. We hypothesize that the difference in cell viability and autophagy expression between KRAS mutant and KRAS wildtype cells after treatment with erlotinib can be of therapeutic value to treat CRC patients carrying KRAS mutations.
    Keywords:  EGFR; KRAS; autophagy; cancer; colorectal; erlotinib
    DOI:  https://doi.org/10.3390/cimb46070447
  52. Mol Med Rep. 2024 Sep;pii: 172. [Epub ahead of print]30(3):
    The role and mechanism of action of miR‑92a in endothelial cell autophagy.
    Weili Cao, Boxin Zhao, Lin Gui, Xueyuan Sun, Zhiyong Zhang, Lijuan Huang.
      Although microRNAs (miRNAs/miRs) serve a significant role in the autophagy of vascular endothelial cells (ECs), the effect of miR‑92a on the autophagy of ECs is currently unclear. Therefore, the present study aimed to investigate the impact of miR‑92a on autophagy in ECs and the underlying molecular processes that control this biological activity. Firstly, an autophagy model of EA.hy926 cells was generated via treatment with the autophagy inducer rapamycin (rapa‑EA.hy926 cells). The expression levels of miR‑92a were then detected by reverse transcription‑quantitative PCR, and the effect of miR‑92a expression on the autophagic activity of rapa‑EA.hy926 cells was studied by overexpressing or inhibiting miR‑92a. The level of autophagy was evaluated by western blot analysis, immunofluorescence staining and transmission electron microscopy. Dual‑luciferase reporter assays were used to confirm the interaction between miR‑92a and FOXO3. The results demonstrated that the expression levels of miR‑92a were decreased in the rapa‑EA.hy926 cell autophagy model. Furthermore, overexpression and inhibition of miR‑92a revealed that upregulation of miR‑92a in these cells inhibited autophagy, whereas miR‑92a knockdown promoted it. It was also confirmed that miR‑92a directly bound to the 3'‑untranslated region of the autophagy‑related gene FOXO3 and reduced its expression. In conclusion, the present study suggested that miR‑92a inhibits autophagy activity in EA.hy926 cells by targeting FOXO3.
    Keywords:  EA.hy926 cells; autophagy; cardiovascular disease; microRNA‑92a
    DOI:  https://doi.org/10.3892/mmr.2024.13296
  53. Viruses. 2024 Jul 19. pii: 1161. [Epub ahead of print]16(7):
    Regulation of Mitochondria-Derived Immune Activation by 'Antiviral' TRIM Proteins.
    Seeun Oh, Michael A Mandell.
      Mitochondria are key orchestrators of antiviral responses that serve as platforms for the assembly and activation of innate immune-signaling complexes. In response to viral infection, mitochondria can be triggered to release immune-stimulatory molecules that can boost interferon production. These same molecules can be released by damaged mitochondria to induce pathogenic, antiviral-like immune responses in the absence of infection. This review explores how members of the tripartite motif-containing (TRIM) protein family, which are recognized for their roles in antiviral defense, regulate mitochondria-based innate immune activation. In antiviral defense, TRIMs are essential components of immune signal transduction pathways and function as directly acting viral restriction factors. TRIMs carry out conceptually similar activities when controlling immune activation related to mitochondria. First, they modulate immune-signaling pathways that can be activated by mitochondrial molecules. Second, they co-ordinate the direct removal of mitochondria and associated immune-activating factors through mitophagy. These insights broaden the scope of TRIM actions in innate immunity and may implicate TRIMs in diseases associated with mitochondria-derived inflammation.
    Keywords:  MAVS; MDA5; RIG-I; STING; TBK1; TRIM; antiviral defense; autophagy; cGAS; inflammation; interferon; mitochondria; mitophagy; restriction factor; tripartite motif
    DOI:  https://doi.org/10.3390/v16071161
  54. Curr Issues Mol Biol. 2024 Jun 27. 46(7): 6580-6599
    The Autophagic and Apoptotic Death of Forebrain Neurons of Rats with Global Brain Ischemia Is Diminished by the Intranasal Administration of Insulin: Possible Mechanism of Its Action.
    Irina O Zakharova, Liubov V Bayunova, Daria K Avrova, Alina D Tretyakova, Alexander O Shpakov, Natalia F Avrova.
      Insulin is a promising neuroprotector. To better understand the mechanism of insulin action, it was important to show its ability to diminish autophagic neuronal death in animals with brain ischemic and reperfusion injury. In forebrain ischemia and reperfusion, the number of live neurons in the hippocampal CA1 region and frontal cortex of rats decreased to a large extent. Intracerebroventricular administration of the autophagy and apoptosis inhibitors to ischemic rats significantly increased the number of live neurons and showed that the main part of neurons died from autophagy and apoptosis. Intranasal administration of 0.5 IU of insulin per rat (before ischemia and daily during reperfusion) increased the number of live neurons in the hippocampal CA1 region and frontal brain cortex. In addition, insulin significantly diminished the level of autophagic marker LC3B-II in these forebrain regions, which markedly increased during ischemia and reperfusion. Our studies demonstrated for the first time the ability of insulin to decrease autophagic neuronal death, caused by brain ischemia and reperfusion. Insulin administered intranasally activated the Akt-kinase (activating the mTORC1 complex, which inhibits autophagy) and inhibited the AMP-activated protein kinase (which activates autophagy) in the hippocampus and frontal cortex of rats with brain ischemia and reperfusion.
    Keywords:  apoptosis; autophagy; forebrain ischemia; intranasal insulin; neuronal viability; protein kinases
    DOI:  https://doi.org/10.3390/cimb46070392
  55. Sci Transl Med. 2024 Jul 24. 16(757): eadk1731
    Targeting ferritinophagy impairs quiescent cancer stem cells in acute myeloid leukemia in vitro and in vivo models.
    Clement Larrue, Sarah Mouche, Paolo Angelino, Maxime Sajot, Rudy Birsen, Olivier Kosmider, Thomas Mckee, François Vergez, Christian Recher, Véronique Mansat-De Mas, Qiong Gu, Jun Xu, Petros Tsantoulis, Jean-Emmanuel Sarry, Jerome Tamburini.
      Acute myeloid leukemia (AML) remains a challenging hematological malignancy with poor prognosis and limited treatment options. Leukemic stem cells (LSCs) contribute to therapeutic failure, relapse, and adverse outcome. This study investigates the role of quiescence and related molecular mechanisms in AML pathogenesis and LSC functions to identify potential therapeutic targets. Transcriptomic analysis revealed that the LSC-enriched quiescent cell population has a distinct gene signature with prognostic relevance in patients with AML. Mechanistically, quiescent blasts exhibit increased autophagic activity, which contributes to their sustained viability. Proteomic profiling uncovered differential requirements for iron metabolism between quiescent and cycling cells, revealing a unique dependence of quiescent cells on ferritinophagy, a selective form of autophagy mediated by nuclear receptor coactivator 4 (NCOA4), which regulates iron bioavailability. We evaluated the therapeutic potential of inhibiting NCOA4-mediated ferritinophagy using genetic knockdown and chemical inhibition approaches. In vitro assays showed that suppression of NCOA4 was toxic to leukemic blasts, particularly the CD34+CD38- LSC-enriched population, without affecting normal CD34+ hematopoietic progenitors. In vivo studies using murine patient-derived xenograft (PDX) models of AML confirmed that NCOA4 inhibition reduced tumor burden and impaired LSC viability and self-renewal, indicating a specific vulnerability of these cells to ferritinophagy disruption. Our findings underscore the role of NCOA4-mediated ferritinophagy in maintaining LSC quiescence and function and suggest that targeting this pathway may be an effective therapeutic strategy for AML. This study highlights the potential of NCOA4 inhibition to improve AML outcomes and paves the way for future research and clinical development.
    DOI:  https://doi.org/10.1126/scitranslmed.adk1731
  56. Mol Metab. 2024 Jul 19. pii: S2212-8778(24)00128-5. [Epub ahead of print] 101997
    Esrra regulates Rplp1-mediated translation of lysosome proteins suppressed in metabolic dysfunction-associated steatohepatitis and reversed by alternate day fasting.
    Madhulika Tripathi, Karine Gauthier, Reddemma Sandireddy, Jin Zhou, Priyanka Guptta, Suganya Sakthivel, Wei Wen Teo, Yadanar Than Naing, Kabilesh Arul, Keziah Tikno, Sung-Hee Park, Yajun Wu, Lijin Wang, Boon-Huat Bay, Lei Sun, Vincent Giguere, Pierce K H Chow, Sujoy Ghosh, Donald P McDonnell, Paul M Yen, Brijesh K Singh.
       OBJECTIVE: Currently, little is known about the mechanism(s) regulating global and specific protein translation during metabolic dysfunction-associated steatohepatitis (MASH; previously known as non-alcoholic steatohepatitis, NASH).
    METHODS: Unbiased label-free quantitative proteome, puromycin-labelling and polysome profiling were used to understand protein translation activity in vitro and in vivo.
    RESULTS: We observed a global decrease in protein translation during lipotoxicity in human primary hepatocytes, mouse hepatic AML12 cells, and livers from a dietary mouse model of MASH. Interestingly, proteomic analysis showed that Rplp1, which regulates ribosome and translation pathways, was one of the most downregulated proteins. Moreover, decreased Esrra expression and binding to the Rplp1 promoter, diminished Rplp1 gene expression during lipotoxicity. This, in turn, reduced global protein translation and Esrra/Rplp1-dependent translation of lysosome (Lamp2, Ctsd) and autophagy (sqstm1, Map1lc3b) proteins. Of note, Esrra did not increase its binding to these gene promoters or their gene transcription, confirming its regulation of their translation during lipotoxicity. Notably, hepatic Esrra-Rplp1-dependent translation of lysosomal and autophagy proteins also was impaired in MASH patients and liver-specific Esrra knockout mice. Remarkably, alternate day fasting induced Esrra-Rplp1-dependent expression of lysosomal proteins, restored autophagy, and reduced lipotoxicity, inflammation, and fibrosis in hepatic cell culture and in vivo models of MASH.
    CONCLUSIONS: Esrra regulation of Rplp1-mediated translation of lysosome/autolysosome proteins was downregulated during MASH. Alternate day fasting activated this novel pathway and improved MASH, suggesting that Esrra and Rplp1 may serve as therapeutic targets for MASH. Our findings also provided the first example of a nuclear hormone receptor, Esrra, to not only regulate transcription but also protein translation, via induction of Rplp1.
    Keywords:  Estrogen related receptor alpha (ERRα/Esrra); Lysosome; Metabolic dysfunction-associated steatohepatitis (MASH); Protein translation; Ribosome
    DOI:  https://doi.org/10.1016/j.molmet.2024.101997
  57. Pharmacol Res. 2024 Jul 24. pii: S1043-6618(24)00269-X. [Epub ahead of print] 107324
    The Role of Polyphenols in Modulating Mitophagy: Implications for Therapeutic Interventions.
    Xinyu Lin, Wenkai Liu, Xizhuo Hu, Zhiqiang Liu, Fang Wang, Jinlian Wang.
      This review rigorously assesses the burgeoning research into the role of polyphenols in modulating mitophagy, an essential cellular mechanism for the targeted removal of impaired mitochondria. These natural compounds, known for their low toxicity, are underscored for their potential in therapeutic strategies against a diverse array of diseases, such as neurodegenerative, cardiovascular, and musculoskeletal disorders. The analysis penetrates deeply into the molecular mechanisms whereby polyphenols promote mitophagy, particularly by influencing crucial signaling pathways and transcriptional regulators, including the phosphatase and tensin homolog (PTEN) induced putative kinase 1 (PINK1)/parkin and forkhead box O3 (FOXO3a) pathways. Noteworthy discoveries include the neuroprotective properties of resveratrol and curcumin, which affect both autophagic pathways and mitochondrial dynamics, and the pioneering integration of polyphenols with other natural substances to amplify therapeutic effectiveness. Furthermore, the review confronts the issue of polyphenol bioavailability and emphasizes the imperative for clinical trials to corroborate their therapeutic viability. By delivering an exhaustive synthesis of contemporary insights and recent advancements in polyphenol and mitophagy research, this review endeavors to catalyze additional research and foster the creation of innovative therapeutic modalities that exploit the distinctive attributes of polyphenols to manage and prevent disease.
    Keywords:  Mitophagy; Natural products; Polyphenols; Signaling pathways; Therapeutic interventions
    DOI:  https://doi.org/10.1016/j.phrs.2024.107324
  58. BMC Cancer. 2024 Jul 26. 24(1): 902
    MARCH1 negatively regulates TBK1-mTOR signaling pathway by ubiquitinating TBK1.
    Xiao Li, Kai Cheng, Meng-Di Shang, Yong Yang, Bin Hu, Xi Wang, Xiao-Dan Wei, Yan-Chun Han, Xiao-Gang Zhang, Meng-Hua Dong, Zhen-Lin Yang, Jiu-Qiang Wang.
       BACKGROUND: TBK1 positively regulates the growth factor-mediated mTOR signaling pathway by phosphorylating mTOR. However, it remains unclear how the TBK1-mTOR signaling pathway is regulated. Considering that STING not only interacts with TBK1 but also with MARCH1, we speculated that MARCH1 might regulate the mTOR signaling pathway by targeting TBK1. The aim of this study was to determine whether MARCH1 regulates the mTOR signaling pathway by targeting TBK1.
    METHODS: The co-immunoprecipitation (Co-IP) assay was used to verify the interaction between MARCH1 with STING or TBK1. The ubiquitination of STING or TBK1 was analyzed using denatured co-immunoprecipitation. The level of proteins detected in the co-immunoprecipitation or denatured co-immunoprecipitation samples were determined by Western blotting. Stable knocked-down cells were constructed by infecting lentivirus bearing the related shRNA sequences. Scratch wound healing and clonogenic cell survival assays were used to detect the migration and proliferation of breast cancer cells.
    RESULTS: We showed that MARCH1 played an important role in growth factor-induced the TBK1- mTOR signaling pathway. MARCH1 overexpression attenuated the growth factor-induced activation of mTOR signaling pathway, whereas its deficiency resulted in the opposite effect. Mechanistically, MARCH1 interacted with and promoted the K63-linked ubiquitination of TBK1. This ubiquitination of TBK1 then attenuated its interaction with mTOR, thereby inhibiting the growth factor-induced mTOR signaling pathway. Importantly, faster proliferation induced by MARCH1 deficiency was weakened by mTOR, STING, or TBK1 inhibition.
    CONCLUSION: MARCH1 suppressed growth factors mediated the mTOR signaling pathway by targeting the STING-TBK1-mTOR axis.
    Keywords:  Growth factors; MARCH1; STING; TBK1; mTOR
    DOI:  https://doi.org/10.1186/s12885-024-12667-y
  59. Microorganisms. 2024 Jul 18. pii: 1458. [Epub ahead of print]12(7):
    Assessing the Presence of Phosphoinositides on Autophagosomal Membrane in Yeast by Live Cell Imaging.
    Jing-Zhen Song, Yi-He Feng, Valentina Sergevnina, Jing Zhu, Hui Li, Zhiping Xie.
      The formation of autophagosomes mediating the sequestration of cytoplasmic materials is the central step of autophagy. Several phosphoinositides, which are signaling molecules on the membrane, are involved in autophagy. However, it is not always clear whether these phosphoinositides act directly at the site of autophagosome formation, or indirectly via the regulation of other steps or pathways. To address this question, we used a set of phosphoinositide probes to systematically examine their potential presence on autophagosomal membranes in yeast (Saccharomyces cerevisiae). We verified the specificity of these probes using mutant cells deficient in the production of the corresponding phosphoinositides. We then examined starved yeast cells co-expressing a phosphoinositide probe together with an autophagosomal membrane marker, 2Katushka2S-Atg8. Our data revealed that PtdIns(4,5)P2 and PtdIns(3,5)P2 were mainly present on the plasma membrane and vacuolar membrane, respectively. We observed only occasional co-localization between the PtdIns(4)P probe and Atg8, some of which may represent the transient passage of a PtdIns(4)P-containing structure near the autophagosomal membrane. In contrast, substantial colocalization of the PtdIns(3)P probe with Atg8 was observed. Taken together, our data indicate that only PtdIns(3)P is present in a substantial amount on the autophagosomal membrane. For other phosphoinositides involved in autophagy, either their presence on the autophagosomal membrane is very transient, or they act on other cellular membranes to regulate autophagy.
    Keywords:  autophagy; phosphoinositides; protein trafficking; yeast
    DOI:  https://doi.org/10.3390/microorganisms12071458
  60. Mol Cells. 2024 Jul 20. pii: S1016-8478(24)00121-3. [Epub ahead of print] 100096
    Targeting Cellular Adaptive Responses to Glutaminolysis Perturbation for Cancer Therapy.
    Minjoong Kim, Sunsook Hwang, Seung Min Jeong.
      Metabolic aberrations, notably deviations in glutamine metabolism, are crucial in the oncogenic process, offering vital resources for the unlimited proliferation and enhanced survival capabilities of cancer cells. The dependency of malignant cells on glutamine metabolism has led to the proposition of targeted therapeutic strategies. However, the capability of cancer cells to initiate adaptive responses undermines the efficacy of these therapeutic interventions. This review meticulously examines the multifaceted adaptive mechanisms that cancer cells deploy to sustain survival and growth following the disruption of glutamine metabolism. Emphasis is placed on the roles of transcription factors, alterations in metabolic pathways, the mTORC1 signaling axis, autophagy, macropinocytosis, nucleotide biosynthesis, and the scavenging of reactive oxygen species. Thus, the delineation and subsequent targeting of these adaptive responses in the context of therapies aimed at glutamine metabolism offer a promising avenue for circumventing drug resistance in cancer treatment.
    Keywords:  adaptive response; cancer therapy; glutamine metabolism
    DOI:  https://doi.org/10.1016/j.mocell.2024.100096
  61. Proc Natl Acad Sci U S A. 2024 Jul 30. 121(31): e2321929121
    Iron regulatory protein 2 contributes to antimicrobial immunity by preserving lysosomal function in macrophages.
    Chen Cheng, Zhiyao Xing, Wenxin Zhang, Lei Zheng, Hongting Zhao, Xiao Zhang, Yibing Ding, Tong Qiao, Yi Li, Esther G Meyron-Holtz, Fanis Missirlis, Zhiwen Fan, Kuanyu Li.
      Colorectal cancer and Crohn's disease patients develop pyogenic liver abscesses due to failures of immune cells to fight off bacterial infections. Here, we show that mice lacking iron regulatory protein 2 (Irp2), globally (Irp2-/-) or myeloid cell lineage (Lysozyme 2 promoter-driven, LysM)-specifically (Irp2ΔLysM), are highly susceptible to liver abscesses when the intestinal tissue was injured with dextran sodium sulfate treatment. Further studies demonstrated that Irp2 is required for lysosomal acidification and biogenesis, both of which are crucial for bacterial clearance. In Irp2-deficient liver tissue or macrophages, the nuclear location of transcription factor EB (Tfeb) was remarkably reduced, leading to the downregulation of Tfeb target genes that encode critical components for lysosomal biogenesis. Tfeb mislocalization was reversed by hypoxia-inducible factor 2 inhibitor PT2385 and, independently, through inhibition of lactic acid production. These experimental findings were confirmed clinically in patients with Crohn's disease and through bioinformatic searches in databases from Crohn's disease or ulcerative colitis biopsies showing loss of IRP2 and transcription factor EB (TFEB)-dependent lysosomal gene expression. Overall, our study highlights a mechanism whereby Irp2 supports nuclear translocation of Tfeb and lysosomal function, preserving macrophage antimicrobial activity and protecting the liver against invading bacteria during intestinal inflammation.
    Keywords:  HIF2; IRP2; TFEB localization; lactic acid; lysosomal function
    DOI:  https://doi.org/10.1073/pnas.2321929121
  62. J Med Life. 2024 Mar;17(3): 261-272
    The effect of intermittent fasting on preventing obesity-related early aging from a molecular and cellular perspective.
    Nurma Yuliyanasari, Purwo Sri Rejeki, Hanik Badriyah Hidayati, Phawinee Subsomwong, Muhammad Miftahussurur.
      Obesity is a global health concern owing to its association with numerous degenerative diseases and the fact that it may lead to early aging. Various markers of aging, including telomere attrition, epigenetic alterations, altered protein homeostasis, mitochondrial dysfunction, cellular senescence, stem cell disorders, and intercellular communication, are influenced by obesity. Consequently, there is a critical need for safe and effective approaches to prevent obesity and mitigate the onset of premature aging. In recent years, intermittent fasting (IF), a dietary strategy that alternates between periods of fasting and feeding, has emerged as a promising dietary strategy that holds potential in counteracting the aging process associated with obesity. This article explores the molecular and cellular mechanisms through which IF affects obesity-related early aging. IF regulates various physiological processes and organ systems, including the liver, brain, muscles, intestines, blood, adipose tissues, endocrine system, and cardiovascular system. Moreover, IF modulates key signaling pathways such as AMP-activated protein kinase (AMPK), sirtuins, phosphatidylinositol 3-kinase (PI3K)/Akt, mammalian target of rapamycin (mTOR), and fork head box O (FOXO). By targeting these pathways, IF has the potential to attenuate aging phenotypes associated with obesity-related early aging. Overall, IF offers promising avenues for promoting healthier lifestyles and mitigating the premature aging process in individuals affected by obesity.
    Keywords:  ADF, alternate-day fasting; ADMF, alternate-day modified fasting; AMPK, AMP-activated protein kinase; BMI, body mass index; FOXO, fork head box O; IF, intermittent fasting; IIS, insulin/insulin-like growth factor signaling; PF, periodic fasting; PGC-1α, peroxisome proliferator-activated receptor gamma coactivator 1-alpha; PI3K, phosphatidylinositol 3-kinase; TRE, time-restricted eating; aging; human health; intermittent fasting; mTOR, mammalian target of rapamycin; obesity; β-HB, β-hydroxy butyric acid
    DOI:  https://doi.org/10.25122/jml-2023-0370
  63. Cell Rep. 2024 Jul 23. pii: S2211-1247(24)00874-X. [Epub ahead of print]43(8): 114545
    Secondary interactions in ubiquitin-binding domains achieve linkage or substrate specificity.
    Martin A Michel, Simon Scutts, David Komander.
      Small ubiquitin-binding domains (UBDs) recognize small surface patches on ubiquitin with weak affinity, and it remains a conundrum how specific cellular responses may be achieved. Npl4-type zinc-finger (NZF) domains are ∼30 amino acid, compact UBDs that can provide two ubiquitin-binding interfaces, imposing linkage specificity to explain signaling outcomes. We here comprehensively characterize the linkage preference of human NZF domains. TAB2 prefers Lys6 and Lys63 linkages phosphorylated on Ser65, explaining why TAB2 recognizes depolarized mitochondria. Surprisingly, most NZF domains do not display chain linkage preference, despite conserved, secondary interaction surfaces. This suggests that some NZF domains may specifically bind ubiquitinated substrates by simultaneously recognizing substrate and an attached ubiquitin. We show biochemically and structurally that the NZF1 domain of the E3 ligase HOIPbinds preferentially to site-specifically ubiquitinated forms of NEMO and optineurin. Thus, despite their small size, UBDs may impose signaling specificity via multivalent interactions with ubiquitinated substrates.
    Keywords:  CP: Molecular biology; IKK; autophagy; mono-ubiquitination; optineurin; ubiquitin binding domain; ubiquitin chain linkage; ubiquitin code
    DOI:  https://doi.org/10.1016/j.celrep.2024.114545
  64. Int J Mol Sci. 2024 Jul 14. pii: 7709. [Epub ahead of print]25(14):
    Gastrodin Improves the Activity of the Ubiquitin-Proteasome System and the Autophagy-Lysosome Pathway to Degrade Mutant Huntingtin.
    He Sun, Miao Li, Yunling Li, Na Zheng, Jiaxin Li, Xiang Li, Yingying Liu, Qianyun Ji, Liping Zhou, Jingwen Su, Wanxu Huang, Zhongbo Liu, Peng Liu, Libo Zou.
      Gastrodin (GAS) is the main chemical component of the traditional Chinese herb Gastrodia elata (called "Tianma" in Chinese), which has been used to treat neurological conditions, including headaches, epilepsy, stroke, and memory loss. To our knowledge, it is unclear whether GAS has a therapeutic effect on Huntington's disease (HD). In the present study, we evaluated the effect of GAS on the degradation of mutant huntingtin protein (mHtt) by using PC12 cells transfected with N-terminal mHtt Q74. We found that 0.1-100 μM GAS had no effect on the survival rate of Q23 and Q74 PC12 cells after 24-48 h of incubation. The ubiquitin-proteasome system (UPS) is the main system that clears misfolded proteins in eukaryotic cells. Mutated Htt significantly upregulated total ubiquitinated protein (Ub) expression, decreased chymotrypsin-like, trypsin-like and caspase-like peptidase activity, and reduced the colocalization of the 20S proteasome with mHtt. GAS (25 μM) attenuated all of the abovementioned pathological changes, and the regulatory effect of GAS on mHtt was found to be abolished by MG132, a proteasome inhibitor. The autophagy-lysosome pathway (ALP) is another system for misfolded protein degradation. Although GAS downregulated the expression of autophagy markers (LC3II and P62), it increased the colocalization of LC3II with lysosomal associated membrane protein 1 (LAMP1), which indicates that ALP was activated. Moreover, GAS prevented mHtt-induced neuronal damage in PC12 cells. GAS has a selective effect on mHtt in Q74 PC12 cells and has no effect on Q23 and proteins encoded by other genes containing long CAGs, such as Rbm33 (10 CAG repeats) and Hcn1 (>30 CAG repeats). Furthermore, oral administration of 100 mg/kg GAS increased grip strength and attenuated mHtt aggregates in B6-hHTT130-N transgenic mice. This is a high dose (100 mg/kg GAS) when compared with experiments on HD mice with other small molecules. We will design more doses to evaluate the dose-response relationship of the inhibition effect of GAS on mHtt in our next study. In summary, GAS can promote the degradation of mHtt by activating the UPS and ALP, making it a potential therapeutic agent for HD.
    Keywords:  autophagy–lysosome pathway; gastrodin; mutant huntingtin protein; neurodegeneration; ubiquitin–proteasome system
    DOI:  https://doi.org/10.3390/ijms25147709
  65. Int J Mol Sci. 2024 Jul 15. pii: 7738. [Epub ahead of print]25(14):
    PKR Mediates the Mitochondrial Unfolded Protein Response through Double-Stranded RNA Accumulation under Mitochondrial Stress.
    Fedho Kusuma, Soyoung Park, Kim Anh Nguyen, Rosalie Elvira, Duckgue Lee, Jaeseok Han.
      Mitochondrial stress, resulting from dysfunction and proteostasis disturbances, triggers the mitochondrial unfolded protein response (UPRMT), which activates gene encoding chaperones and proteases to restore mitochondrial function. Although ATFS-1 mediates mitochondrial stress UPRMT induction in C. elegans, the mechanisms relaying mitochondrial stress signals to the nucleus in mammals remain poorly defined. Here, we explored the role of protein kinase R (PKR), an eIF2α kinase activated by double-stranded RNAs (dsRNAs), in mitochondrial stress signaling. We found that UPRMT does not occur in cells lacking PKR, indicating its crucial role in this process. Mechanistically, we observed that dsRNAs accumulate within mitochondria under stress conditions, along with unprocessed mitochondrial transcripts. Furthermore, we demonstrated that accumulated mitochondrial dsRNAs in mouse embryonic fibroblasts (MEFs) deficient in the Bax/Bak channels are not released into the cytosol and do not induce the UPRMT upon mitochondrial stress, suggesting a potential role of the Bax/Bak channels in mediating the mitochondrial stress response. These discoveries enhance our understanding of how cells maintain mitochondrial integrity, respond to mitochondrial dysfunction, and communicate stress signals to the nucleus through retrograde signaling. This knowledge provides valuable insights into prospective therapeutic targets for diseases associated with mitochondrial stress.
    Keywords:  PKR; UPRMT; integrated stress response; mitochondrial dsRNAs; mitochondrial stress
    DOI:  https://doi.org/10.3390/ijms25147738
  66. J Biol Chem. 2024 Jul 24. pii: S0021-9258(24)02104-5. [Epub ahead of print] 107603
    UNVEILING DEFECTS OF SECRETION MECHANISMS IN PARKINSON'S DISEASE.
    Francesca Filippini, Thierry Galli.
      Neurodegenerative diseases are characterized by progressive dysfunction and loss of specific sets of neurons. While extensive research has focused on elucidating the genetic and epigenetic factors and molecular mechanisms underlying these disorders, emerging evidence highlights the critical role of secretion in the pathogenesis, possibly even onset, and progression of neurodegenerative diseases, suggesting the occurrence of non-cell-autonomous mechanisms. Secretion is a fundamental process that regulates intercellular communication, supports cellular homeostasis, and orchestrates various physiological functions in the body. Defective secretion can impair the release of neurotransmitters and other signaling molecules, disrupting synaptic transmission and compromising neuronal survival. It can also contribute to the accumulation, misfolding, and aggregation of disease-associated proteins, leading to neurotoxicity and neuronal dysfunction. In this review, we discuss the implications of defective secretion in the context of Parkinson's disease, emphasizing its role in protein aggregation, synaptic dysfunction, extracellular vesicle secretion and neuroinflammation. We propose a multiple-hit model whereby protein accumulation and secretory defects must be combined for the onset and progression of the disease.
    Keywords:  Parkinson’s disease; astrocytes; extracellular vesicles; microglia; protein secretion; synapse
    DOI:  https://doi.org/10.1016/j.jbc.2024.107603
  67. J Neurosci. 2024 Jul 25. pii: e0198242024. [Epub ahead of print]
    TFEB/3 govern repair Schwann cell generation and function following peripheral nerve injury.
    Akash A Patel, Hyukmin Kim, Raghu Ramesh, Anthony Marquez, Moler M Faraj, Henri Antikainen, Andrew S Lee, Adriana Torres, Imran M Khawaja, Corey Heffernan, Edward M Bonder, Patrice Maurel, John Svaren, Young-Jin Son, Radek Dobrowolski, Haesun A Kim.
      TFEB and TFE3 (TFEB/3), key regulators of lysosomal biogenesis and autophagy, play diverse roles depending on cell type. This study highlights a hitherto unrecognized role of TFEB/3 crucial for peripheral nerve repair. Specifically, they promote the generation of progenitor-like repair Schwann cells after axonal injury. In Schwann cell-specific TFEB/3 double knock-out mice of either sex, the TFEB/3 loss disrupts the transcriptomic reprogramming that is essential for the formation of repair Schwann cells. Consequently, mutant mice fail to populate the injured nerve with repair Schwann cells and exhibit defects in axon-regrowth, target reinnervation, and functional recovery. TFEB/3 deficiency inhibits the expression of injury-responsive repair Schwann cell genes, despite the continued expression of c-Jun, a previously identified regulator of repair Schwann cell function. TFEB/3 binding motifs are enriched in the enhancer regions of injury-responsive genes, suggesting their role in repair gene activation. Autophagy-dependent myelin breakdown is not impaired despite TFEB/3 deficiency. These findings underscore a unique role of TFEB/3 in adult Schwann cells that is required for proper peripheral nerve regeneration.Significance Statement Peripheral nerves have been recognized for their efficient regenerative capabilities compared to the central nervous system neurons. This is due to the remarkable ability of Schwann cells to undergo a reprogramming process, transforming into progenitor-like repair Schwann cells that actively contribute to axon regeneration and overall nerve repair. However, the specific transcriptional regulators responsible for initiating this transformation in the adult peripheral nerve have remained elusive. Our study elucidates a previously undescribed, injury-responsive function of TFEB/3 in adult Schwann cells, showcasing its ability to promote tissue repair. Our findings hold important implications for enhancing nerve regeneration by bolstering the regenerative capacity of glial cells, thereby contributing to advancements in the field of neural tissue repair.
    DOI:  https://doi.org/10.1523/JNEUROSCI.0198-24.2024
  68. Nat Commun. 2024 Jul 23. 15(1): 5970
    Mutant mice with rod-specific VPS35 deletion exhibit retinal α-synuclein pathology-associated degeneration.
    Cheng Fu, Nan Yang, Jen-Zen Chuang, Nobuyuki Nakajima, Satoshi Iraha, Neeta Roy, Zhenquan Wu, Zhichun Jiang, Wataru Otsu, Roxana A Radu, Howard Hua Yang, Maxwell Ping Lee, Tilla S Worgall, Wen-Cheng Xiong, Ching-Hwa Sung.
      Vacuolar protein sorting 35 (VPS35), the core component of the retromer complex which regulates endosomal trafficking, is genetically linked with Parkinson's disease (PD). Impaired vision is a common non-motor manifestation of PD. Here, we show mouse retinas with VPS35-deficient rods exhibit synapse loss and visual deficit, followed by progressive degeneration concomitant with the emergence of Lewy body-like inclusions and phospho-α-synuclein (P-αSyn) aggregation. Ultrastructural analyses reveal VPS35-deficient rods accumulate aggregates in late endosomes, deposited as lipofuscins bound to P-αSyn. Mechanistically, we uncover a protein network of VPS35 and its interaction with HSC70. VPS35 deficiency promotes sequestration of HSC70 and P-αSyn aggregation in late endosomes. Microglia which engulf lipofuscins and P-αSyn aggregates are activated, displaying autofluorescence, observed as bright dots in fundus imaging of live animals, coinciding with pathology onset and progression. The Rod∆Vps35 mouse line is a valuable tool for further mechanistic investigation of αSyn lesions and retinal degenerative diseases.
    DOI:  https://doi.org/10.1038/s41467-024-50189-0
  69. Biomed Pharmacother. 2024 Jul 24. pii: S0753-3322(24)01083-7. [Epub ahead of print]178 117199
    Therapeutic effect of nicotinamide mononucleotide on Alzheimer's disease through activating autophagy and anti-oxidative stress.
    Rui-Yin Ma, Li Li, Hui Yang, Bin Zou, Rui-Xia Ma, Yue Zhang, Miao-Miao Wu, Peng Chen, Yao Yao, Juan Li.
      Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the deposition of β-amyloid (Aβ) plaques and neurofibrillary tangles composed of tau protein in the brain. These neuropathological hallmarks contribute to cognitive impairment by inducing neuronal loss in the cerebral cortex and hippocampus. Unfortunately, current therapeutic approaches only target symptomatic relief and do not impede disease progression. Nicotinamide mononucleotide (NMN), a precursor of nicotinamide adenine dinucleotide (NAD+), has emerged as a promising candidate for the treatment of age-related neurodegenerative disorders. NMN supplementation could restore NAD+ levels, thereby alleviating neuronal damage and slowing the progression of AD and other aging-associated diseases. AD is closely associated with autophagic impairment and oxidative stress. Our in vivo experiments demonstrated that NMN could ameliorate pathological and behavioral impairments in AD mice. Specifically, NMN enhanced autophagy and promoted p-tau clearance. Meanwhile, NMN could activate the Nrf2/Keap1/NQO1 pathway, thereby reducing the oxidative stress. Immunofluorescence results demonstrated that NMN could alleviate neuronal damage in AD mice. Furthermore, in vitro results showed that the p-tau clearance and antioxidant stress effects of NMN were suppressed by autophagy inhibitor, chloroquine (CQ) or bafilomycin A1 (BafA1), in Aβ-induced PC12 cells. Lastly, when Nrf2 was knocked down, the antioxidant stress, autophagy enhancement, and p-tau clearance effects of NMN were all inhibited. In conclusion, our research indicates that NMN exerts therapeutic effect against AD by activating autophagy and the Nrf2/Keap1/NQO1 pathway through a mutual regulating mechanism of autophagy and antioxidative stress. These findings highlight the promising potential of NMN for the treatment of AD.
    Keywords:  Alzheimer’s disease; Autophagy; NMN; Nrf2; Oxidative stress; P-tau
    DOI:  https://doi.org/10.1016/j.biopha.2024.117199
  70. Int J Mol Sci. 2024 Jul 09. pii: 7530. [Epub ahead of print]25(14):
    Natural Compounds for Preventing Age-Related Diseases and Cancers.
    Mi-Ran Ki, Sol Youn, Dong Hyun Kim, Seung Pil Pack.
      Aging is a multifaceted process influenced by hereditary factors, lifestyle, and environmental elements. As time progresses, the human body experiences degenerative changes in major functions. The external and internal signs of aging manifest in various ways, including skin dryness, wrinkles, musculoskeletal disorders, cardiovascular diseases, diabetes, neurodegenerative disorders, and cancer. Additionally, cancer, like aging, is a complex disease that arises from the accumulation of various genetic and epigenetic alterations. Circadian clock dysregulation has recently been identified as an important risk factor for aging and cancer development. Natural compounds and herbal medicines have gained significant attention for their potential in preventing age-related diseases and inhibiting cancer progression. These compounds demonstrate antioxidant, anti-inflammatory, anti-proliferative, pro-apoptotic, anti-metastatic, and anti-angiogenic effects as well as circadian clock regulation. This review explores age-related diseases, cancers, and the potential of specific natural compounds in targeting the key features of these conditions.
    Keywords:  age-related diseases; aging; autophagy; cancer; circadian rhythms; natural compounds
    DOI:  https://doi.org/10.3390/ijms25147530
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