bims-auttor Biomed News
on Autophagy and mTOR
Issue of 2023‒07‒16
sixty-six papers selected by
Viktor Korolchuk, Newcastle University
  1. ATPase activity of DFCP1 controls selective autophagy.
  2. A new perspective on the autophagic and non-autophagic functions of the GABARAP protein family: a potential therapeutic target for human diseases.
  3. Autophagy in Crohn's Disease: Converging on Dysfunctional Innate Immunity.
  4. Role of TFEB in Diseases Associated with Lysosomal Dysfunction.
  5. Lysosomal cystine export regulates mTORC1 signaling to guide kidney epithelial cell fate specialization.
  6. Potent New Targets for Autophagy Enhancement to Delay Neuronal Ageing.
  7. Defects in Mitochondrial Biogenesis Drive Mitochondrial Alterations in PINK1-deficient Human Dopamine Neurons.
  8. Cyclin-G-associated kinase GAK/dAux regulates autophagy initiation via ULK1/Atg1 in glia.
  9. Tethering ATG16L1 or LC3 induces targeted autophagic degradation of protein aggregates and mitochondria.
  10. Inhibition of phosphodiesterase 4D suppresses mTORC1 signaling and pancreatic cancer growth.
  11. Combinatorial selective ER-phagy remodels the ER during neurogenesis.
  12. ARL6IP5 Ameliorates α-Synuclein Burden by Inducing Autophagy via Preventing Ubiquitination and Degradation of ATG12.
  13. The Troyer syndrome protein spartin mediates selective autophagy of lipid droplets.
  14. The Role of mTORC1 Pathway and Autophagy in Resistance to Platinum-Based Chemotherapeutics.
  15. Exosome-Autophagy Crosstalk in Enveloped Virus Infection.
  16. The Atg1 complex, Atg9, and Vac8 recruit PI3K complex I to the pre-autophagosomal structure.
  17. Deciphering the mitophagy receptor network identifies a crucial role for OPTN (optineurin) in acute myeloid leukemia.
  18. Lipofuscin Granule Accumulation Requires Autophagy Activation.
  19. AMPK/mTOR pathway significance in healthy liver and non-alcoholic fatty liver disease and its progression.
  20. Update on Autophagy Inhibitors in Cancer: Opening up to a Therapeutic Combination with Immune Checkpoint Inhibitors.
  21. Co-targeting autophagy and NRF2 signaling triggers mitochondrial superoxide to sensitize oral cancer stem cells for cisplatin-induced apoptosis.
  22. Polyploidy-associated autophagy promotes larval tracheal histolysis at Drosophila metamorphosis.
  23. Ethanol inhibits pancreatic acinar cell autophagy through upregulation of ATG4B, mediating pathologic responses of alcoholic pancreatitis.
  24. The Highs and Lows of Memantine-An Autophagy and Mitophagy Inducing Agent That Protects Mitochondria.
  25. BAG3: An enticing therapeutic target for idiopathic pulmonary fibrosis.
  26. The engagement of autophagy in maniac disease.
  27. The role of mitochondria and mitophagy in cell senescence.
  28. Autophagy regulation and protein kinase activity of PIK3C3 controls sertoli cell polarity through its negative regulation on SCIN (scinderin).
  29. The Interplay of Autophagy and Oxidative Stress in the Kidney: What Do We Know?
  30. Role of autophagy-related proteins ATG8f and ATG8h in the maintenance of autophagic activity in Arabidopsis roots under phosphate starvation.
  31. Autophagy-ER stress crosstalk controls mucus secretion and susceptibility to gut inflammation.
  32. A protein kinase coordinates cycles of autophagy and glutaminolysis in invasive hyphae of the fungus Magnaporthe oryzae within rice cells.
  33. Autophagy Regulators in Cancer.
  34. ATG4B antagonizes antiviral immunity by GABARAP-directed autophagic degradation of TBK1.
  35. A partial Drp1 knockout improves autophagy flux independent of mitochondrial function.
  36. Autophagy and cancer drug resistance in dialogue: Pre-clinical and clinical evidence.
  37. The autophagy-related protein ATG5 is a central mediator of a non-canonical autophagy pathway hijacked by HIV-1 to weaken the host's response to infection.
  38. Exogenous galanin alleviates hepatic steatosis by promoting autophagy via the AMPK-mTOR pathway.
  39. Hyperbaric oxygen treatment increases intestinal stem cell proliferation through the mTORC1/S6K1 signaling pathway in Mus musculus.
  40. Vps4a Regulates Autophagic Flux to Prevent Hypertrophic Cardiomyopathy.
  41. Interactions of Autophagy and the Immune System in Health and Diseases.
  42. Corynoxine B targets at HMGB1/2 to enhance autophagy for α-synuclein clearance in fly and rodent models of Parkinson's disease.
  43. hsa-miR-320a mediated exosome release under PD stress conditions rescue mitochondrial ROS and cell death in the recipient neuronal and glial cells.
  44. Bidirectional interplay between SARS-CoV-2 and autophagy.
  45. Crosstalk between autophagy and CSCs: molecular mechanisms and translational implications.
  46. Hypoxia-reprogramed megamitochondrion contacts and engulfs lysosome to mediate mitochondrial self-digestion.
  47. Glucose promotes cell growth and casein synthesis via ATF4/Nrf2-Sestrin2- AMPK-mTORC1 pathway in dairy cow mammary epithelial cells.
  48. Lysophosphatidic acid is associated with oocyte maturation by enhancing autophagy via PI3K-AKT-mTOR signaling pathway in granulosa cells.
  49. Molecular targets of spermidine: implications for cancer suppression.
  50. SREBP-1 upregulates lipophagy to maintain cholesterol homeostasis in brain tumor cells.
  51. Swainsonine inhibits autophagic degradation and causes cytotoxicity by reducing CTSD O-GlcNAcylation.
  52. Role of autophagy in the pathogenesis and regulation of pain.
  53. Glc7/PP1 dephosphorylates histone H3T11 to regulate autophagy and telomere silencing in response to nutrient availability.
  54. Recency memory is altered in cocaine-withdrawn adolescent rats: Implication of cortical mTOR signaling.
  55. Proteasomal Stimulation by MK886 and Its Derivatives Can Rescue Tau-Induced Neurite Pathology.
  56. Mitochondrial Dysfunction and Skeletal Muscle Atrophy: Causes, Mechanisms, and Treatment Strategies.
  57. Longitudinal in vivo metabolic labeling reveals tissue-specific mitochondrial proteome turnover rates and proteins selectively altered by parkin deficiency.
  58. Quercetin ameliorates non-alcoholic fatty liver disease (NAFLD) via the promotion of AMPK-mediated hepatic mitophagy.
  59. Loss of STING in parkin mutant flies suppresses muscle defects and mitochondria damage.
  60. Identification and Characterization of Protein Interactions with the Major Niemann-Pick Type C Disease Protein in Yeast Reveals Pathways of Therapeutic Potential.
  61. Dietary Apigenin Relieves Body Weight and Glycolipid Metabolic Disturbance via Pro-Browning of White Adipose Mediated by Autophagy Inhibition.
  62. Lysosome pH-regulated H+ /K+ switching channel involved in maintaining lysosomal homeostasis.
  63. Piceatannol Protects PC-12 Cells against Oxidative Damage and Mitochondrial Dysfunction by Inhibiting Autophagy via SIRT3 Pathway.
  64. Bioimaging tools reveal copper processing in fish cells by mitophagy.
  65. Molecular mechanism of caloric restriction mimetics-mediated neuroprotection of age-related neurodegenerative diseases: an emerging therapeutic approach.
  66. Increasing autophagy ameliorates all-trans-retinal-activated NLRP3 inflammasomes in human THP-1 macrophages.
  1. Nat Commun. 2023 Jul 08. 14(1): 4051
    ATPase activity of DFCP1 controls selective autophagy.
    Viola Nähse, Camilla Raiborg, Kia Wee Tan, Sissel Mørk, Maria Lyngaas Torgersen, Eva Maria Wenzel, Mireia Nager, Veijo T Salo, Terje Johansen, Elina Ikonen, Kay Oliver Schink, Harald Stenmark.
      Cellular homeostasis is governed by removal of damaged organelles and protein aggregates by selective autophagy mediated by cargo adaptors such as p62/SQSTM1. Autophagosomes can assemble in specialized cup-shaped regions of the endoplasmic reticulum (ER) known as omegasomes, which are characterized by the presence of the ER protein DFCP1/ZFYVE1. The function of DFCP1 is unknown, as are the mechanisms of omegasome formation and constriction. Here, we demonstrate that DFCP1 is an ATPase that is activated by membrane binding and dimerizes in an ATP-dependent fashion. Whereas depletion of DFCP1 has a minor effect on bulk autophagic flux, DFCP1 is required to maintain the autophagic flux of p62 under both fed and starved conditions, and this is dependent on its ability to bind and hydrolyse ATP. While DFCP1 mutants defective in ATP binding or hydrolysis localize to forming omegasomes, these omegasomes fail to constrict properly in a size-dependent manner. Consequently, the release of nascent autophagosomes from large omegasomes is markedly delayed. While knockout of DFCP1 does not affect bulk autophagy, it inhibits selective autophagy, including aggrephagy, mitophagy and micronucleophagy. We conclude that DFCP1 mediates ATPase-driven constriction of large omegasomes to release autophagosomes for selective autophagy.
    DOI:  https://doi.org/10.1038/s41467-023-39641-9
  2. Mol Cell Biochem. 2023 Jul 13.
    A new perspective on the autophagic and non-autophagic functions of the GABARAP protein family: a potential therapeutic target for human diseases.
    Jiawei Chen, Hong Zhao, Meiqing Liu, Linxi Chen.
      Mammalian autophagy-related protein Atg8, including the LC3 subfamily and GABARAP subfamily. Atg8 proteins play a vital role in autophagy initiation, autophagosome formation and transport, and autophagy-lysosome fusion. GABARAP subfamily proteins (GABARAPs) share a high degree of homology with LC3 family proteins, and their unique roles are often overlooked. GABARAPs are as indispensable as LC3 in autophagy. Deletion of GABARAPs fails autophagy flux induction and autophagy lysosomal fusion, which leads to the failure of autophagy. GABARAPs are also involved in the transport of selective autophagy receptors. They are engaged in various particular autophagy processes, including mitochondrial autophagy, endoplasmic reticulum autophagy, Golgi autophagy, centrosome autophagy, and dorphagy. Furthermore, GABARAPs are closely related to the transport and delivery of the inhibitory neurotransmitter γ-GABAA and the angiotensin II AT1 receptor (AT1R), tumor growth, metastasis, and prognosis. GABARAPs also have been confirmed to be involved in various diseases, such as cancer, cardiovascular disease, and neurodegenerative diseases. In order to better understand the role and therapeutic potential of GABARAPs, this article comprehensively reviews the autophagic and non-autophagic functions of GABARAPs, as well as the research progress of the role and mechanism of GABARAPs in cancer, cardiovascular diseases and neurodegenerative diseases. It emphasizes the significance of GABARAPs in the clinical prevention and treatment of diseases, and may provide new therapeutic ideas and targets for human diseases. GABARAP and GABARAPL1 in the serum of cancer patients are positively correlated with the prognosis of patients, which can be used as a clinical biomarker, predictor and potential therapeutic target. GABARAP family proteins: autophagy and non-autophagy related functions in diseases. By Figdraw ( https://www.figdraw.com ).
    Keywords:  Cancer; Cardiovascular diseases; GABARAP/LC3; Immune inflammatory response; Neurodegenerative disease; Selective autophagy
    DOI:  https://doi.org/10.1007/s11010-023-04800-5
  3. Cells. 2023 Jul 04. pii: 1779. [Epub ahead of print]12(13):
    Autophagy in Crohn's Disease: Converging on Dysfunctional Innate Immunity.
    Kibrom M Alula, Arianne L Theiss.
      Crohn's disease (CD) is a chronic inflammatory bowel disease marked by relapsing, transmural intestinal inflammation driven by innate and adaptive immune responses. Autophagy is a multi-step process that plays a critical role in maintaining cellular homeostasis by degrading intracellular components, such as damaged organelles and invading bacteria. Dysregulation of autophagy in CD is revealed by the identification of several susceptibility genes, including ATG16L1, IRGM, NOD2, LRRK2, ULK1, ATG4, and TCF4, that are involved in autophagy. In this review, the role of altered autophagy in the mucosal innate immune response in the context of CD is discussed, with a specific focus on dendritic cells, macrophages, Paneth cells, and goblet cells. Selective autophagy, such as xenophagy, ERphagy, and mitophagy, that play crucial roles in maintaining intestinal homeostasis in these innate immune cells, are discussed. As our understanding of autophagy in CD pathogenesis evolves, the development of autophagy-targeted therapeutics may benefit subsets of patients harboring impaired autophagy.
    Keywords:  ATG16L1; Crohn’s disease; ER stress; IRGM; NOD2; genetic susceptibility; inflammatory bowel disease; innate immunity; mitochondria; mitophagy; xenophagy
    DOI:  https://doi.org/10.3390/cells12131779
  4. Adv Exp Med Biol. 2023 ;1415 319-325
    Role of TFEB in Diseases Associated with Lysosomal Dysfunction.
    Hsuan-Yeh Pan, Mallika Valapala.
      Transcription factor EB (TFEB) plays a very important role in the maintenance of cellular homeostasis. TFEB is a transcription factor that regulates the expression of several genes in the Coordinated Lysosomal Expression and Regulation (CLEAR) network. The CLEAR network genes are known to regulate many processes associated with the autophagy pathway and lysosome biogenesis. Lysosomes, which are degradative organelles in the cell, are associated with several cellular mechanisms, such as autophagy and phagocytosis. Recent studies have shown that TFEB dysregulation and lysosomal dysfunction are associated with several degenerative diseases. Thus, enhancing TFEB activity and accompanied induction of lysosomal function and autophagy can have tremendous therapeutic potential for the treatment of several degenerative diseases including age-related macular degeneration (AMD). In this chapter, we briefly illustrate the expression and regulation of TFEB in response to several cellular stressors and discuss the effects of TFEB overexpression to induce cellular clearance functions.
    Keywords:  Age-related macular degeneration (AMD); Lysosomal dysfunction; Neurodegeneration; Reactive oxygen species (ROS); Retinal pigment epithelium (RPE); Transcription factor EB (TFEB)
    DOI:  https://doi.org/10.1007/978-3-031-27681-1_46
  5. Nat Commun. 2023 Jul 14. 14(1): 3994
    Lysosomal cystine export regulates mTORC1 signaling to guide kidney epithelial cell fate specialization.
    Marine Berquez, Zhiyong Chen, Beatrice Paola Festa, Patrick Krohn, Svenja Aline Keller, Silvia Parolo, Mikhail Korzinkin, Anna Gaponova, Endre Laczko, Enrico Domenici, Olivier Devuyst, Alessandro Luciani.
      Differentiation is critical for cell fate decisions, but the signals involved remain unclear. The kidney proximal tubule (PT) cells reabsorb disulphide-rich proteins through endocytosis, generating cystine via lysosomal proteolysis. Here we report that defective cystine mobilization from lysosomes through cystinosin (CTNS), which is mutated in cystinosis, diverts PT cells towards growth and proliferation, disrupting their functions. Mechanistically, cystine storage stimulates Ragulator-Rag GTPase-dependent recruitment of mechanistic target of rapamycin complex 1 (mTORC1) and its constitutive activation. Re-introduction of CTNS restores nutrient-dependent regulation of mTORC1 in knockout cells, whereas cell-permeant analogues of L-cystine, accumulating within lysosomes, render wild-type cells resistant to nutrient withdrawal. Therapeutic mTORC1 inhibition corrects lysosome and differentiation downstream of cystine storage, and phenotypes in preclinical models of cystinosis. Thus, cystine serves as a lysosomal signal that tailors mTORC1 and metabolism to direct epithelial cell fate decisions. These results identify mechanisms and therapeutic targets for dysregulated homeostasis in cystinosis.
    DOI:  https://doi.org/10.1038/s41467-023-39261-3
  6. Cells. 2023 Jun 30. pii: 1753. [Epub ahead of print]12(13):
    Potent New Targets for Autophagy Enhancement to Delay Neuronal Ageing.
    Janka Szinyákovics, Fanni Keresztes, Eszter Anna Kiss, Gergő Falcsik, Tibor Vellai, Tibor Kovács.
      Autophagy is a lysosomal-dependent degradation process of eukaryotic cells responsible for breaking down unnecessary and damaged intracellular components. Autophagic activity gradually declines with age due to genetic control, and this change contributes to the accumulation of cellular damage at advanced ages, thereby causing cells to lose their functionality and viability. This could be particularly problematic in post-mitotic cells including neurons, the mass destruction of which leads to various neurodegenerative diseases. Here, we aim to uncover new regulatory points where autophagy could be specifically activated and test these potential drug targets in neurodegenerative disease models of Drosophila melanogaster. One possible way to activate autophagy is by enhancing autophagosome-lysosome fusion that creates the autolysosome in which the enzymatic degradation happens. The HOPS (homotypic fusion and protein sorting) and SNARE (Snap receptor) protein complexes regulate the fusion process. The HOPS complex forms a bridge between the lysosome and autophagosome with the assistance of small GTPase proteins. Thus, small GTPases are essential for autolysosome maturation, and among these proteins, Rab2 (Ras-associated binding 2), Rab7, and Arl8 (Arf-like 8) are required to degrade the autophagic cargo. For our experiments, we used Drosophila melanogaster as a model organism. Nerve-specific small GTPases were silenced and overexpressed. We examined the effects of these genetic interventions on lifespan, climbing ability, and autophagy. Finally, we also studied the activation of small GTPases in a Parkinson's disease model. Our results revealed that GTP-locked, constitutively active Rab2 (Rab2-CA) and Arl8 (Arl8-CA) expression reduces the levels of the autophagic substrate p62/Ref(2)P in neurons, extends lifespan, and improves the climbing ability of animals during ageing. However, Rab7-CA expression dramatically shortens lifespan and inhibits autophagy. Rab2-CA expression also increases lifespan in a Parkinson's disease model fly strain overexpressing human mutant (A53T) α-synuclein protein. Data provided by this study suggests that Rab2 and Arl8 serve as potential targets for autophagy enhancement in the Drosophila nervous system. In the future, it might be interesting to assess the effect of Rab2 and Arl8 coactivation on autophagy, and it would also be worthwhile to validate these findings in a mammalian model and human cell lines. Molecules that specifically inhibit Rab2 or Arl8 serve as potent drug candidates to modulate the activity of the autophagic process in treating neurodegenerative pathologies. In the future, it would be reasonable to investigate which GAP enzyme can inhibit Rab2 or Arl8 specifically, but not affect Rab7, with similar medical purposes.
    Keywords:  Arl8; Drosophila; Parkinson’s disease; Rab2; Rab7; ageing; autophagy; neurodegeneration
    DOI:  https://doi.org/10.3390/cells12131753
  7. bioRxiv. 2023 Jun 26. pii: 2023.06.23.546087. [Epub ahead of print]
    Defects in Mitochondrial Biogenesis Drive Mitochondrial Alterations in PINK1-deficient Human Dopamine Neurons.
    Hu Wang, Rong Chen, Liming Xiao, Manoj Kumar, Jesús Acevedo-Cintrón, Joanna Siuda, Dariusz Koziorowski, Zbigniew K Wszolek, Valina L Dawson, Ted M Dawson.
      Mutations and loss of activity in the protein kinase PINK1 play a role in the pathogenesis of Parkinson's disease (PD). PINK1 regulates many aspects of mitochondrial quality control including mitochondrial autophagy (mitophagy), fission, fusion, transport, and biogenesis. Defects in mitophagy are though to play a predominant role in the loss of dopamine (DA) neurons in PD. Here we show that, although there are defects in mitophagy in human DA neurons lacking PINK1, mitochondrial deficits induced by the absence of PINK1 are primarily due to defects in mitochondrial biogenesis. Upregulation of PARIS and the subsequent down regulation of PGC-1α accounts for the mitochondrial biogenesis defects. CRISPR/Cas9 knockdown of PARIS completely restores the mitochondrial biogenesis defects and mitochondrial function without impacting the deficits in mitophagy due to the absence of PINK1. These results highlight the importance mitochondrial biogenesis in the pathogenesis of PD due to inactivation or loss of PINK1 in human DA neurons.
    DOI:  https://doi.org/10.1101/2023.06.23.546087
  8. Proc Natl Acad Sci U S A. 2023 07 18. 120(29): e2301002120
    Cyclin-G-associated kinase GAK/dAux regulates autophagy initiation via ULK1/Atg1 in glia.
    Shiping Zhang, Shuanglong Yi, Linfang Wang, Shuhua Li, Honglei Wang, Li Song, Jiayao Ou, Min Zhang, Ruiqi Wang, Mengxiao Wang, Yuchen Zheng, Kai Yang, Tong Liu, Margaret S Ho.
      Autophagy is a major means for the elimination of protein inclusions in neurons in neurodegenerative diseases such as Parkinson's disease (PD). Yet, the mechanism of autophagy in the other brain cell type, glia, is less well characterized and remains largely unknown. Here, we present evidence that the PD risk factor, Cyclin-G-associated kinase (GAK)/Drosophila homolog Auxilin (dAux), is a component in glial autophagy. The lack of GAK/dAux increases the autophagosome number and size in adult fly glia and mouse microglia, and generally up-regulates levels of components in the initiation and PI3K class III complexes. GAK/dAux interacts with the master initiation regulator UNC-51like autophagy activating kinase 1/Atg1 via its uncoating domain and regulates the trafficking of Atg1 and Atg9 to autophagosomes, hence controlling the onset of glial autophagy. On the other hand, lack of GAK/dAux impairs the autophagic flux and blocks substrate degradation, suggesting that GAK/dAux might play additional roles. Importantly, dAux contributes to PD-like symptoms including dopaminergic neurodegeneration and locomotor function in flies. Our findings identify an autophagy factor in glia; considering the pivotal role of glia under pathological conditions, targeting glial autophagy is potentially a therapeutic strategy for PD.
    Keywords:  GAK; Parkinson’s disease; autophagy; dAux; glia
    DOI:  https://doi.org/10.1073/pnas.2301002120
  9. Autophagy. 2023 Jul 13. 1-17
    Tethering ATG16L1 or LC3 induces targeted autophagic degradation of protein aggregates and mitochondria.
    Ligang Mei, Xiaorong Chen, Fujing Wei, Xue Huang, Lu Liu, Jia Yao, Jing Chen, Xunguang Luo, Zhuolin Wang, Aimin Yang.
      Proteolysis-targeting chimeras (PROTACs) based on the ubiquitin-proteasome system have made great progress in the field of drug discovery. There is mounting evidence that the accumulation of aggregation-prone proteins or malfunctioning organelles is associated with the occurrence of various age-related neurodegenerative disorders and cancers. However, PROTACs are inefficient for the degradation of such large targets due to the narrow entrance channel of the proteasome. Macroautophagy (hereafter referred to as autophagy) is known as a self-degradative process involved in the degradation of bulk cytoplasmic components or specific cargoes that are sequestered into autophagosomes. In the present study, we report the development of a generalizable strategy for the targeted degradation of large targets. Our results suggested that tethering large target models to phagophore-associated ATG16L1 or LC3 induced targeted autophagic degradation of the large target models. Furthermore, we successfully applied this autophagy-targeting degradation strategy to the targeted degradation of HTT65Q aggregates and mitochondria. Specifically, chimeras consisting of polyQ-binding peptide 1 (QBP) and ATG16L1-binding peptide (ABP) or LC3-interacting region (LIR) induced targeted autophagic degradation of pathogenic HTT65Q aggregates; and the chimeras consisting of mitochondria-targeting sequence (MTS) and ABP or LIR promoted targeted autophagic degradation of dysfunctional mitochondria, hence ameliorating mitochondrial dysfunction in a Parkinson disease cell model and protecting cells from apoptosis induced by the mitochondrial stress agent FCCP. Therefore, this study provides a new strategy for the selective proteolysis of large targets and enrich the toolkit for autophagy-targeting degradation.Abbreviations: ABP: ATG16L1-binding peptide; ATG16L1: autophagy related 16 like 1; ATTEC: autophagy-tethering compound; AUTAC: autophagy-targeting chimera; AUTOTAC: autophagy-targeting chimera; Baf A1: bafilomycin A1; BCL2: BCL2 apoptosis regulator; CALCOCO2/NDP52: calcium binding and coiled-coil domain 2; CASP3: caspase 3; CPP: cell-penetrating peptide; CQ: chloroquine phosphate; DAPI: 4',6-diamidino-2-phenylindole; DCM: dichloromethane; DMF: N,N-dimethylformamide; DMSO: dimethyl sulfoxide; EBSS: Earle's balanced salt solution; FCCP: carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone; FITC: fluorescein-5-isothiocyanate; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GFP: green fluorescent protein; HEK293: human embryonic kidney 293; HEK293T: human embryonic kidney 293T; HPLC: high-performance liquid chromatography; HRP: horseradish peroxidase; HTT: huntingtin; LIR: LC3-interacting region; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MFF: mitochondrial fission factor; MTS: mitochondria-targeting sequence; NBR1: NBR1 autophagy cargo receptor; NLRX1: NLR family member X1; OPTN: optineurin; P2A: self-cleaving 2A peptide; PB1: Phox and Bem1p; PBS: phosphate-buffered saline; PE: phosphatidylethanolamine; PINK1: PTEN induced kinase 1; PRKN: parkin RBR E3 ubiquitin protein ligase; PROTACs: proteolysis-targeting chimeras; QBP: polyQ-binding peptide 1; SBP: streptavidin-binding peptide; SDS-PAGE: sodium dodecyl sulfate-polyacrylamide gel electrophoresis; SPATA33: spermatogenesis associated 33; TIMM23: translocase of inner mitochondrial membrane 23; TMEM59: transmembrane protein 59; TOMM20: translocase of outer mitochondrial membrane 20; UBA: ubiquitin-associated; WT: wild type.
    Keywords:  ATG16L1; HTT65Q aggregates; LC3; autophagy-targeting degradation; mitochondria; proteolysis-targeting chimeras
    DOI:  https://doi.org/10.1080/15548627.2023.2234797
  10. JCI Insight. 2023 07 10. pii: e158098. [Epub ahead of print]8(13):
    Inhibition of phosphodiesterase 4D suppresses mTORC1 signaling and pancreatic cancer growth.
    Mi-Hyeon Jeong, Greg Urquhart, Cheryl Lewis, Zhikai Chi, Jenna L Jewell.
      The mammalian target of rapamycin complex 1 (mTORC1) senses multiple upstream stimuli to orchestrate anabolic and catabolic events that regulate cell growth and metabolism. Hyperactivation of mTORC1 signaling is observed in multiple human diseases; thus, pathways that suppress mTORC1 signaling may help to identify new therapeutic targets. Here, we report that phosphodiesterase 4D (PDE4D) promotes pancreatic cancer tumor growth by increasing mTORC1 signaling. GPCRs paired to Gαs proteins activate adenylyl cyclase, which in turn elevates levels of 3',5'-cyclic adenosine monophosphate (cAMP), whereas PDEs catalyze the hydrolysis of cAMP to 5'-AMP. PDE4D forms a complex with mTORC1 and is required for mTORC1 lysosomal localization and activation. Inhibition of PDE4D and the elevation of cAMP levels block mTORC1 signaling via Raptor phosphorylation. Moreover, pancreatic cancer exhibits an upregulation of PDE4D expression, and high PDE4D levels predict the poor overall survival of patients with pancreatic cancer. Importantly, FDA-approved PDE4 inhibitors repress pancreatic cancer cell tumor growth in vivo by suppressing mTORC1 signaling. Our results identify PDE4D as an important activator of mTORC1 and suggest that targeting PDE4 with FDA-approved inhibitors may be beneficial for the treatment of human diseases with hyperactivated mTORC1 signaling.
    Keywords:  Cancer; Cell Biology
    DOI:  https://doi.org/10.1172/jci.insight.158098
  11. bioRxiv. 2023 Jun 26. pii: 2023.06.26.546565. [Epub ahead of print]
    Combinatorial selective ER-phagy remodels the ER during neurogenesis.
    Melissa J Hoyer, Ian R Smith, Julia C Paoli, Yizhi Jiang, Joao A Paulo, J Wade Harper.
      The endoplasmic reticulum (ER) has a vast proteomic landscape to perform many diverse functions including protein and lipid synthesis, calcium ion flux, and inter-organelle communication. The ER proteome is remodeled in part through membrane-embedded receptors linking ER to degradative autophagy machinery (selective ER-phagy) 1, 2 . A refined tubular ER network 3, 4 is formed in neurons within highly polarized dendrites and axons 5, 6 . Autophagy-deficient neurons in vivo display axonal ER accumulation within synaptic ER boutons, 7 and the ER-phagy receptor FAM134B has been genetically linked with human sensory and autonomic neuropathy 8, 9 . However, mechanisms, including receptor selectivity, that define ER remodeling by autophagy in neurons are limited. Here, we combine a genetically tractable induced neuron (iNeuron) system for monitoring extensive ER remodeling during differentiation with proteomic and computational tools to create a quantitative landscape of ER proteome remodeling via selective autophagy. Through analysis of single and combinatorial ER-phagy receptor mutants, we delineate the extent to which each receptor contributes to both magnitude and selectivity of ER clearance via autophagy for individual ER protein cargos. We define specific subsets of ER curvature-shaping proteins or lumenal proteins as preferred clients for distinct receptors. Using spatial sensors and flux reporters, we demonstrate receptor-specific autophagic capture of ER in axons, which correlates with aberrant ER accumulation in axons of ER-phagy receptor or autophagy-deficient neurons. This molecular inventory of ER proteome remodeling and versatile genetic toolkit provides a quantitative framework for understanding contributions of individual ER-phagy receptors for reshaping ER during cell state transitions.
    DOI:  https://doi.org/10.1101/2023.06.26.546565
  12. Int J Mol Sci. 2023 Jun 22. pii: 10499. [Epub ahead of print]24(13):
    ARL6IP5 Ameliorates α-Synuclein Burden by Inducing Autophagy via Preventing Ubiquitination and Degradation of ATG12.
    Ibrar Siddique, Kajal Kamble, Sakshi Gupta, Kavita Solanki, Sumnil Bhola, Nuzhat Ahsan, Sarika Gupta.
      Recent advanced studies in neurodegenerative diseases have revealed several links connecting autophagy and neurodegeneration. Autophagy is the major cellular degradation process for the removal of toxic protein aggregates responsible for neurodegenerative diseases. More than 30 autophagy-related proteins have been identified as directly participating in the autophagy process. Proteins regulating the process of autophagy are much more numerous and unknown. To address this, in our present study, we identified a novel regulator (ARL6IP5) of neuronal autophagy and showed that the level of ARL6IP5 decreases in the brain with age and in Parkinson's disease in mice and humans. Moreover, a cellular model of PD (Wild type and A53T mutant α-synuclein overexpression) has also shown decreased levels of ARL6IP5. ARL6IP5 overexpression reduces α-synuclein aggregate burden and improves cell survival in an A53T model of Parkinson's disease. Interestingly, detailed mechanistic studies revealed that ARL6IP5 is an autophagy inducer. ARL6IP5 enhances Rab1-dependent autophagosome initiation and elongation by stabilizing free ATG12. We report for the first time that α-synuclein downregulates ARL6IP5 to inhibit autophagy-dependent clearance of toxic aggregates that exacerbate neurodegeneration.
    Keywords:  ARL6IP5 (ADP-ribosylation-like factor 6 interacting protein 5); Parkinson’s disease (PD); SH-SY5Y cells; autophagy; neurodegeneration; α-synuclein
    DOI:  https://doi.org/10.3390/ijms241310499
  13. Nat Cell Biol. 2023 Jul 13.
    The Troyer syndrome protein spartin mediates selective autophagy of lipid droplets.
    Jeeyun Chung, Joongkyu Park, Zon Weng Lai, Talley J Lambert, Ruth C Richards, Jiuchun Zhang, Tobias C Walther, Robert V Farese.
      Lipid droplets (LDs) are crucial organelles for energy storage and lipid homeostasis. Autophagy of LDs is an important pathway for their catabolism, but the molecular mechanisms mediating LD degradation by selective autophagy (lipophagy) are unknown. Here we identify spartin as a receptor localizing to LDs and interacting with core autophagy machinery, and we show that spartin is required to deliver LDs to lysosomes for triglyceride mobilization. Mutations in SPART (encoding spartin) lead to Troyer syndrome, a form of complex hereditary spastic paraplegia1. Interfering with spartin function in cultured human neurons or murine brain neurons leads to LD and triglyceride accumulation. Our identification of spartin as a lipophagy receptor, thus, suggests that impaired LD turnover contributes to Troyer syndrome development.
    DOI:  https://doi.org/10.1038/s41556-023-01178-w
  14. Int J Mol Sci. 2023 Jun 26. pii: 10651. [Epub ahead of print]24(13):
    The Role of mTORC1 Pathway and Autophagy in Resistance to Platinum-Based Chemotherapeutics.
    Zhenrui Pan, Hanxiao Zhang, Svetlana Dokudovskaya.
      Cisplatin (cis-diamminedichloroplatinum I) is a platinum-based drug, the mainstay of anticancer treatment for numerous solid tumors. Since its approval by the FDA in 1978, the drug has continued to be used for the treatment of half of epithelial cancers. However, resistance to cisplatin represents a major obstacle during anticancer therapy. Here, we review recent findings on how the mTORC1 pathway and autophagy can influence cisplatin sensitivity and resistance and how these data can be applicable for the development of new therapeutic strategies.
    Keywords:  anticancer drug resistance; autophagy; cisplatin; mTORC1 pathway
    DOI:  https://doi.org/10.3390/ijms241310651
  15. Int J Mol Sci. 2023 Jun 25. pii: 10618. [Epub ahead of print]24(13):
    Exosome-Autophagy Crosstalk in Enveloped Virus Infection.
    Yuqi Wang, Linzhu Ren, Haocheng Bai, Qing Jin, Liying Zhang.
      Exosomes, which are extracellular vesicles (EVs) predominantly present in bodily fluids, participate in various physiological processes. Autophagy, an intracellular degradation mechanism, eliminates proteins and damaged organelles by forming double-membrane autophagosomes. These autophagosomes subsequently merge with lysosomes for target degradation. The interaction between autophagy and endosomal/exosomal pathways can occur at different stages, exerting significant influences on normal physiology and human diseases. The interplay between exosomes and the autophagy pathway is intricate. Exosomes exhibit a cytoprotective role by inducing intracellular autophagy, while autophagy modulates the biogenesis and degradation of exosomes. Research indicates that exosomes and autophagy contribute to the infection process of numerous enveloped viruses. Enveloped viruses, comprising viral nucleic acid, proteins, or virions, can be encapsulated within exosomes and transferred between cells via exosomal transport. Consequently, exosomes play a crucial role in the infection of certain viral diseases. This review presents recent findings on the interplay between exosomes and autophagy, as well as their implications in the infection of enveloped viruses, thereby offering valuable insights into the pathogenesis and vaccine research of enveloped virus infection.
    Keywords:  autophagy; extracellular vesicles; relationship; viruses
    DOI:  https://doi.org/10.3390/ijms241310618
  16. J Cell Biol. 2023 08 07. pii: e202210017. [Epub ahead of print]222(8):
    The Atg1 complex, Atg9, and Vac8 recruit PI3K complex I to the pre-autophagosomal structure.
    Kanae Hitomi, Tetsuya Kotani, Nobuo N Noda, Yayoi Kimura, Hitoshi Nakatogawa.
      In macroautophagy, cellular components are sequestered within autophagosomes and transported to lysosomes/vacuoles for degradation. Although phosphatidylinositol 3-kinase complex I (PI3KCI) plays a pivotal role in the regulation of autophagosome biogenesis, little is known about how this complex localizes to the pre-autophagosomal structure (PAS). In Saccharomyces cerevisiae, PI3KCI is composed of PI3K Vps34 and conserved subunits Vps15, Vps30, Atg14, and Atg38. In this study, we discover that PI3KCI interacts with the vacuolar membrane anchor Vac8, the PAS scaffold Atg1 complex, and the pre-autophagosomal vesicle component Atg9 via the Atg14 C-terminal region, the Atg38 C-terminal region, and the Vps30 BARA domain, respectively. While the Atg14-Vac8 interaction is constitutive, the Atg38-Atg1 complex interaction and the Vps30-Atg9 interaction are enhanced upon macroautophagy induction depending on Atg1 kinase activity. These interactions cooperate to target PI3KCI to the PAS. These findings provide a molecular basis for PAS targeting of PI3KCI during autophagosome biogenesis.
    DOI:  https://doi.org/10.1083/jcb.202210017
  17. Autophagy. 2023 Jul 13. 1-15
    Deciphering the mitophagy receptor network identifies a crucial role for OPTN (optineurin) in acute myeloid leukemia.
    Laura M Meyer, Sebastian E Koschade, Jonas B Vischedyk, Marlyn Thoelken, Andrea Gubas, Martin Wegner, Marion Basoglu, Stefan Knapp, Manuel Kaulich, Stefan Eimer, Shabnam Shaid, Christian H Brandts.
      The selective autophagic degradation of mitochondria via mitophagy is essential for preserving mitochondrial homeostasis and, thereby, disease maintenance and progression in acute myeloid leukemia (AML). Mitophagy is orchestrated by a variety of mitophagy receptors whose interplay is not well understood. Here, we established a pairwise multiplexed CRISPR screen targeting mitophagy receptors to elucidate redundancies and gain a deeper understanding of the functional interactome governing mitophagy in AML. We identified OPTN (optineurin) as sole non-redundant mitophagy receptor and characterized its unique role in AML. Knockdown and overexpression experiments demonstrated that OPTN expression is rate-limiting for AML cell proliferation. In a MN1-driven murine transplantation model, loss of OPTN prolonged overall median survival by 7 days (+21%). Mechanistically, we found broadly impaired mitochondrial respiration and function with increased mitochondrial ROS, that most likely caused the proliferation defect. Our results decipher the intertwined network of mitophagy receptors in AML for both ubiquitin-dependent and receptor-mediated mitophagy, identify OPTN as a non-redundant tool to study mitophagy in the context of leukemia and suggest OPTN inhibition as an attractive therapeutic strategy.Abbreviations: AML: acute myeloid leukemia; CRISPR: Clustered Regularly Interspaced Short Palindromic Repeats; CTRL: control; DFP: deferiprone; GI: genetic interaction; KD: knockdown; KO: knockout; ldMBM, lineage-depleted murine bone marrow; LFC: log2 fold change; LIR: LC3-interacting region; LSC: leukemic stem cell; MAGeCK: Model-based Analysis of Genome-wide CRISPR-Cas9 Knockout; MDIVI-1: mitochondrial division inhibitor 1; MOI: multiplicity of infection; MOM: mitochondrial outer membrane; NAC: N-acetyl-L-cysteine; OA: oligomycin-antimycin A; OCR: oxygen consumption rate; OE: overexpression; OPTN: optineurin; PINK1: PTEN induced putative kinase 1; ROS: reactive oxygen species; SEM: standard error of the mean; TCGA: The Cancer Genome Atlas; TEM: transmission electron microscopy; UBD: ubiquitin-binding domain; WT: wild type.
    Keywords:  AML; MN1-driven mouse model; Mitochondrial ROS; Multiplex CRISPR screen; genetic interactions; leukemia
    DOI:  https://doi.org/10.1080/15548627.2023.2230839
  18. Mol Cells. 2023 Jul 13.
    Lipofuscin Granule Accumulation Requires Autophagy Activation.
    Seon Beom Song, Woosung Shim, Eun Seong Hwang.
      Lipofuscins are oxidized lipid and protein complexes that accumulate during cellular senescence and tissue aging, regarded as markers for cellular oxidative damage, tissue aging, and certain aging-associated diseases. Therefore, understanding their cellular biological properties is crucial for effective treatment development. Through traditional microscopy, lipofuscins are readily observed as fluorescent granules thought to accumulate in lysosomes. However, lipofuscin granule formation and accumulation in senescent cells are poorly understood. Thus, this study examined lipofuscin accumulation in human fibroblasts exposed to various stressors. Our results substantiate that in glucose-starved or replicative senescence cells, where elevated oxidative stress levels activate autophagy, lipofuscins predominately appear as granules that co-localize with autolysosomes due to lysosomal acidity or impairment. Meanwhile, autophagosome formation is attenuated in cells experiencing oxidative stress induced by a doxorubicin pulse and chase, and lipofuscin fluorescence granules seldom manifest in the cytoplasm. As Torin-1 treatment activates autophagy, granular lipofuscins intensify and dominate, indicating that autophagy activation triggers their accumulation. Our results suggest that high oxidative stress activates autophagy but fails in lipofuscin removal, leaving an abundance of lipofuscin-filled impaired autolysosomes, referred to as residual bodies. Therefore, future endeavors in treating lipofuscin pathology-associated diseases and dysfunctions through autophagy activation demand meticulous consideration.
    Keywords:  autolysosome; autophagy; cellular senescence; lipofuscin; lipofuscin granule
    DOI:  https://doi.org/10.14348/molcells.2023.0019
  19. J Gastroenterol Hepatol. 2023 Jul 12.
    AMPK/mTOR pathway significance in healthy liver and non-alcoholic fatty liver disease and its progression.
    Ilitch Aquino Marcondes-de-Castro, Pedro Henrique Reis-Barbosa, Thatiany Souza Marinho, Marcia Barbosa Aguila, Carlos Alberto Mandarim-de-Lacerda.
      Obesity is related to several organs, but the liver is particularly affected. Adenosine monophosphate-activated protein kinase (AMPK) is a cellular energy sensor and regulator of liver lipid dysfunction and glucose metabolism. The mechanistic target of rapamycin (mTOR) is a protein kinase regulating cell growth, survival, metabolism, and immunity. Together, these pathways are involved in obesity, insulin resistance, non-alcoholic fatty liver disease (NAFLD) and its progression, and autophagy. During energy demand, liver kinase B (LKB) phosphorylation helps activate the AMPK/mTOR pathways. Likewise, the protein forkhead box O family (FOXO) negatively regulates adipogenesis by binding to the promoter sites of peroxisome proliferator-activated receptor-gamma coactivator 1-alpha, initiating adipogenesis. In addition, acetyl-CoA carboxylase, which regulates de novo lipogenesis, is linked to LKB and FOXO in developing NAFLD. The kinase complex, consisting of Unc-51-like autophagy-activating kinase 1 or 2 (ULK1, ULK2) by stimulating autophagy, and eliminating fat droplets in NAFLD, is regulated by mTORC1 and negatively regulated by AMPK that suppresses liver lipogenesis and increases fatty acid oxidation. Also, ULK1 is essential for initiating phagophore formation, establishing macrophagy, and generating autophagosomes. The selective breakdown of lipid droplets through macroautophagy, or macrolipophagy, occurs on a cellular energy level using free fatty acids. In addition, mTORC1 promotes lipogenesis by activating sterol regulatory element-binding protein. Finding new components and novel regulatory modes in signaling is significant for a better understanding of the AMPK/mTOR pathways, potentially facilitating the development of future diagnostic and therapeutic strategies for NAFLD and its progression to non-alcoholic steatohepatitis, cirrhosis, and hepatocellular carcinoma.
    Keywords:  AMPK/mTOR pathway; autophagy; lipid metabolism; non-alcoholic fatty liver disease; obesity
    DOI:  https://doi.org/10.1111/jgh.16272
  20. Cells. 2023 Jun 23. pii: 1702. [Epub ahead of print]12(13):
    Update on Autophagy Inhibitors in Cancer: Opening up to a Therapeutic Combination with Immune Checkpoint Inhibitors.
    Eloïne Bestion, Eric Raymond, Soraya Mezouar, Philippe Halfon.
      Autophagy is a highly conserved and natural degradation process that helps maintain cell homeostasis through the elimination of old, worn, and defective cellular components, ensuring proper cell energy intake. The degradative pathway constitutes a protective barrier against diverse human diseases including cancer. Autophagy basal level has been reported to be completely dysregulated during the entire oncogenic process. Autophagy influences not only cancer initiation, development, and maintenance but also regulates cancer response to therapy. Currently, autophagy inhibitor candidates mainly target the early autophagy process without any successful preclinical/clinical development. Lessons learned from autophagy pharmaceutical manipulation as a curative option progressively help to improve drug design and to encounter new targets of interest. Combinatorial strategies with autophagy modulators are supported by abundant evidence, especially dealing with immune checkpoint inhibitors, for which encouraging preclinical results have been recently published. GNS561, a PPT1 inhibitor, is a promising autophagy modulator as it has started a phase 2 clinical trial in liver cancer indication, combined with atezolizumab and bevacizumab, an assessment without precedent in the field. This approach paves a new road, leading to the resurgence of anticancer autophagy inhibitors as an attractive therapeutic target in cancer.
    Keywords:  PPT1; autophagy; cancer; clinical trial; combinational therapy; drug inhibitor
    DOI:  https://doi.org/10.3390/cells12131702
  21. Free Radic Biol Med. 2023 Jul 07. pii: S0891-5849(23)00526-9. [Epub ahead of print]
    Co-targeting autophagy and NRF2 signaling triggers mitochondrial superoxide to sensitize oral cancer stem cells for cisplatin-induced apoptosis.
    Prakash P Praharaj, Amruta Singh, Srimanta Patra, Sujit K Bhutia.
      Cancer stem cell (CSC) populations are regulated by autophagy, which in turn modulates tumorigenicity and malignancy. In this study, we demonstrate that cisplatin treatment enriches the CSCs population by increasing autophagosome formation and speeding up autophagosome-lysosome fusion by recruiting RAB7 to autolysosomes. Further, cisplatin treatment stimulates lysosomal activity and increases autophagic flux in oral CD44+ cells. Interestingly, both ATG5-and BECN1-dependent autophagy are essential for maintaining cancer stemness, self-renewal, and resistance to cisplatin-induced cytotoxicity in oral CD44+ cells. Moreover, we discovered that autophagy-deficient (shATG5 and/or shBECN1) CD44+ cells benefited from cisplatin treatment because it activated NRF2 (nuclear factor, erythroid 2 like 2) signaling, which in turn reduces the elevated ROS level enhancing cancer stemness. Genetic inhibition of NRF2 (siNRF2) in autophagy-deficient CD44+ cells increases mtROS level, reducing cisplatin-resistance CSCs, and pre-treatment with mitoTEMPO [a mitochondria-targeted SOD (superoxide dismutase) mimetic] lessened the cytotoxic effect enhancing cancer stemness. We also found that inhibiting autophagy (with CQ) and NRF2 signaling (with ML-385) combinedly increased cisplatin cytotoxicity, thereby suppressing the expansion of oral CD44+ cells; this finding has the potential to be clinically applicable in resolving CSC-associated chemoresistance and tumor relapse in oral cancer.
    Keywords:  Apoptosis; Autophagy; Cancer stem cell; NRF2; Oral cancer; mtROS
    DOI:  https://doi.org/10.1016/j.freeradbiomed.2023.07.008
  22. Autophagy. 2023 Jul 09. 1-10
    Polyploidy-associated autophagy promotes larval tracheal histolysis at Drosophila metamorphosis.
    Beatriz Pino-Jiménez, Panagiotis Giannios, Jordi Casanova.
      Polyploidy is an extended phenomenon in biology. However, its physiological significance and whether it defines specific cell behaviors is not well understood. Here we study its connection to macroautophagy/autophagy, using the larval respiratory system of Drosophila as a model. This system comprises cells with the same function yet with notably different ploidy status, namely diploid progenitors and their polyploid larval counterparts, the latter destined to die during metamorphosis. We identified an association between polyploidy and autophagy and found that higher endoreplication status correlates with elevated autophagy. Finally, we report that tissue histolysis in the trachea during Drosophila metamorphosis is mediated by autophagy, which triggers the apoptosis of polyploid cells.Abbreviations: APF: after pupa formation; Atg: autophagy related; btl: breathless; CycE: Cyclin E; DT: dorsal trunk; fzr: fizzy-related; L3: larval stage 3; PBS: phosphate-buffered saline; RI: RNAi; Tr: tracheal metamere; yki: yorkie.
    Keywords:  Apoptosis; Drosophila; autophagy; polyploidy; progenitor; trachea
    DOI:  https://doi.org/10.1080/15548627.2023.2231828
  23. Am J Physiol Gastrointest Liver Physiol. 2023 Jul 11.
    Ethanol inhibits pancreatic acinar cell autophagy through upregulation of ATG4B, mediating pathologic responses of alcoholic pancreatitis.
    Olga A Mareninova, Sophie R Gretler, Grace E Lee, Michael Pimienta, Yueqiu Qin, Jason M Elperin, Jinliang Ni, Zsolt Razga, Anna S Gukovskaya, Ilya Gukovsky.
      Excessive alcohol intake is a major risk factor for pancreatitis, sensitizing exocrine pancreas to stressors by mechanisms that remain obscure. Impaired autophagy drives non-alcoholic pancreatitis, but the effects of ethanol (EtOH) and alcoholic pancreatitis on autophagy are poorly understood. Here, we find that ethanol reduces autophagosome formation in pancreatic acinar cells, both in a mouse model of alcoholic pancreatitis induced by combination of EtOH diet and cerulein (a CCK ortholog) and in EtOH+CCK treated acinar cells (ex-vivo model). Ethanol treatments decreased pancreatic level of LC3-II, a key mediator of autophagosome formation. This was caused by ethanol-induced upregulation of ATG4B, a cysteine protease which, cell-dependently, regulates the balance between cytosolic LC3-I and membrane-bound LC3-II. We show that ATG4B negatively regulates LC3-II in acinar cells subjected to EtOH treatments. Ethanol raised ATG4B level by inhibiting its degradation, enhanced ATG4B enzymatic activity, and strengthened its interaction with LC3-II. We also found ATG4B increase and impaired autophagy in a dissimilar, non-secretagogue model of alcoholic pancreatitis induced by EtOH plus palmitoleic acid. Adenoviral ATG4B overexpression in acinar cells greatly reduced LC3-II and inhibited autophagy. Further, it aggravated trypsinogen activation and necrosis, mimicking key responses of ex-vivo alcoholic pancreatitis. Conversely, shRNA Atg4B knockdown enhanced autophagosome formation and alleviated ethanol-induced acinar cell damage. The results reveal a novel mechanism whereby ethanol inhibits autophagosome formation and thus sensitizes to pancreatitis, and a key role of ATG4B in ethanol's effects on autophagy. Enhancing pancreatic autophagy, particularly by down-regulating ATG4B, could be beneficial in mitigating the severity of alcoholic pancreatitis.
    Keywords:  CCK; acinar cells; alcohol; autophagy; pancreas
    DOI:  https://doi.org/10.1152/ajpgi.00053.2023
  24. Cells. 2023 Jun 27. pii: 1726. [Epub ahead of print]12(13):
    The Highs and Lows of Memantine-An Autophagy and Mitophagy Inducing Agent That Protects Mitochondria.
    Sholto de Wet, Asandile Mangali, Richard Batt, Jurgen Kriel, Nicola Vahrmeijer, Dana Niehaus, Rensu Theart, Ben Loos.
      Memantine is an FDA-approved, non-competitive NMDA-receptor antagonist that has been shown to have mitochondrial protective effects, improve cell viability and enhance clearance of Aβ42 peptide. Currently, there are uncertainties regarding the precise molecular targets as well as the most favourable treatment concentrations of memantine. Here, we made use of an imaging-based approach to investigate the concentration-dependent effects of memantine on mitochondrial fission and fusion dynamics, autophagy and mitochondrial quality control using a neuronal model of CCCP-induced mitochondrial injury so as to better unpack how memantine aids in promoting neuronal health. GT1-7 murine hypothalamic cells were cultured under standard conditions, treated with a relatively high and low concentration (100 µM and 50 µM) of memantine for 48 h. Images were acquired using a Zeiss 780 PS1 platform. Utilising the mitochondrial event localiser (MEL), we demonstrated clear concentration-dependent effects of memantine causing a protective response to mitochondrial injury. Both concentrations maintained the mitochondrial network volume whilst the low concentration caused an increase in mitochondrial number as well as increased fission and fusion events following CCCP-induced injury. Additionally, we made use of a customised Python-based image processing and analysis pipeline to quantitatively assess memantine-dependent changes in the autophagosomal and lysosomal compartments. Our results revealed that memantine elicits a differential, concentration-dependent effect on autophagy pathway intermediates. Intriguingly, low but not high concentrations of memantine lead to the induction of mitophagy. Taken together, our findings have shown that memantine is able to protect the mitochondrial network by preserving its volume upon mitochondrial injury with high concentrations of memantine inducing macroautophagy, whereas low concentrations lead to the induction of mitophagy.
    Keywords:  autophagy; mitochondrial dynamics; mitochondrial function; mitophagy; proteostasis
    DOI:  https://doi.org/10.3390/cells12131726
  25. J Cell Biochem. 2023 Jul 14.
    BAG3: An enticing therapeutic target for idiopathic pulmonary fibrosis.
    Shashipavan Chillappagari, Andreas Guenther, Poornima Mahavadi.
      Idiopathic pulmonary fibrosis (IPF) is a dreadful and fatal disease of unknown etiology, for which no cure exists. Autophagy, a lysosomal cellular surveillance pathway is insufficiently activated in both alveolar epithelial type II cells and fibroblasts of IPF patient lungs. Fine-tuning this pathway may result in the degradation of the accumulated cargo and influence cell fate. Based on our previous data, we here present our view on modulating autophagy via a unique co-chaperone, namely Bcl2-associated athanogene3 (BAG3) in IPF and discuss about how repurposing drugs that modulate this pathway may emerge as a promising novel therapeutic approach for IPF.
    Keywords:  BAG3; autophagy; idiopathic pulmonary fibrosis; therapeutic intervention
    DOI:  https://doi.org/10.1002/jcb.30446
  26. CNS Neurosci Ther. 2023 Jul 12.
    The engagement of autophagy in maniac disease.
    Yidong Yang, Renxiang Yuan, Yangyang Lu, Chenze Zhu, Chen Zhang, Haifeng Lue, Xiangnan Zhang.
      AIMS: Mania is a prevalent psychiatric disorder with undefined pathological mechanism. Here, we reviewed current knowledge indicating the potential involvement of autophagy dysregulation in mania and further discussed whether targeting autophagy could be a promising strategy for mania therapy.DISCUSSIONS: Accumulating evidence indicated the involvement of autophagy in the pathology of mania. One of the most well-accepted mechanisms underlying mania, circadian dysregulation, showed mutual interaction with autophagy dysfunction. In addition, several first-line drugs for mania therapy were found to regulate neuronal autophagy. Besides, deficiencies in mitochondrial quality control, neurotransmission, and ion channel, which showed causal links to mania, were intimately associated with autophagy dysfunction.
    CONCLUSIONS: Although more efforts should be made to either identify the key pathology of mania, the current evidence supported that autophagy dysregulation may act as a possible mechanism involved in the onset of mania-like symptoms. It is therefore a potential strategy to treat manic disorder by correting autophagy.
    Keywords:  anti-manic drugs; autophagy; circadian rhythm; mania
    DOI:  https://doi.org/10.1111/cns.14353
  27. Adv Protein Chem Struct Biol. 2023 ;pii: S1876-1623(23)00043-3. [Epub ahead of print]136 93-115
    The role of mitochondria and mitophagy in cell senescence.
    Tayyab Ali, Fatma Hussain, Haroon Ur Rashid Kayani, Muhammad Naeem, Fozia Anjum.
      Mitochondrial malfunction and cell senescence have been defined as the hallmarks of aging. Cell senescence leads to the loss of health allied with aging. While deciphering the complex association between mitochondria and cellular senescence, it is observed that senescence has a two-faced nature being beneficial and hazardous. This duality of cellular senescence is associated with circumstantial aspects. During the process of cellular senescence, dysfunctional mitochondria are accumulated, the efficiency of the oxidative phosphorylation process declines along with the enhanced synthesis of reactive oxygen species. It is suggested that reduction in the negative consequences of senescence throughout old age might be accomplished by targeting the mitochondria as all roads lead towards mitochondria. It is unclear how perturbation of mitophagy in senescence results in the accumulation of mitochondria, impairment of mitochondrial biogenesis and onset of diseases. Understanding this complex interplay will bring about a long yet healthy lifespan. But definitely casual and specific players contribute in the initiation and conservation of the cell senescence. Variations in metabolism, quality control and dynamics of mitochondria are observed during cell aging process. Several On-target and Off-target mechanisms can also cause side effects in cellular senescence. Translational research of these mechanisms may lead to effective clinical interventions. This chapter reviews the role of mitochondria, homeostatic mechanisms and mitophagy as drivers and effectors of cell senescence along with multiple signalling pathways that lead to the initiation, maintenance, induction and suppression of cellular aging process during health and disease.
    Keywords:  Autophagy; Cell senescence; Mitophagy; Signaling pathways
    DOI:  https://doi.org/10.1016/bs.apcsb.2023.03.001
  28. Autophagy. 2023 Jul 14. 1-24
    Autophagy regulation and protein kinase activity of PIK3C3 controls sertoli cell polarity through its negative regulation on SCIN (scinderin).
    Kehan Wang, Feifei Kong, Yuexin Qiu, Tao Chen, Jiayi Fu, Xin Jin, Youqiang Su, Yayun Gu, Zhibin Hu, Jing Li.
      Sertoli cells are highly polarized testicular cells that provide a nurturing environment for germ cell development and maturation during spermatogenesis. The class III phosphatidylinositol 3-kinase (PtdIns3K) plays core roles in macroautophagy in various cell types; however, its role in Sertoli cells remains unclear. Here, we generated a mouse line in which the gene encoding the catalytic subunit, Pik3c3, was specifically deleted in Sertoli cells (cKO) and found that after one round of normal spermatogenesis, the cKO mice quickly became infertile and showed disruption of Sertoli cell polarity and impaired spermiogenesis. Subsequent proteomics and phosphoproteomics analyses enriched the F-actin cytoskeleton network involved in the disorganized Sertoli-cell structure in cKO testis which we identified a significant increase of the F-actin negative regulator SCIN (scinderin) and the reduced phosphorylation of HDAC6, an α-tubulin deacetylase. Our results further demonstrated that the accumulation of SCIN in cKO Sertoli cells caused the disorder and disassembly of the F-actin cytoskeleton, which was related to the failure of SCIN degradation through the autophagy-lysosome pathway. Additionally, we found that the phosphorylation of HDAC6 at site S59 by PIK3C3 was essential for its degradation through the ubiquitin-proteasome pathway. As a result, the HDAC6 that accumulated in cKO Sertoli cells deacetylated SCIN at site K189 and led to a disorganized F-actin cytoskeleton. Taken together, our findings elucidate a new mechanism for PIK3C3 in maintaining the polarity of Sertoli cells, in which both its autophagy regulation or protein kinase activities are required for the stabilization of the actin cytoskeleton.Abbreviations: ACTB: actin, beta; AR: androgen receptor; ATG14: autophagy related 14; BafA1: bafilomycin A1; BECN1: beclin 1, autophagy related; BTB: blood-testis barrier; CASP3: caspase 3; CDC42: cell division cycle 42; CDH2: cadherin 2; CHX: cycloheximide; CTNNA1: catenin (cadherin associated protein), alpha 1; CYP11A1: cytochrome P450, family 11, subfamily A, polypeptide 1; EBSS: Earle's balanced salt solution; ES: ectoplasmic specialization; FITC: fluorescein isothiocyanate; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GCNA: germ cell nuclear acidic protein; GJA1: gap junction protein, alpha 1; H2AX: H2A.X variant histone; HDAC6: histone deacetylase 6; KIT: KIT proto-oncogene, receptor tyrosine kinase; LAMP1: lysosomal associated membrane protein 1; MAP3K5: mitogen-activated protein kinase kinase kinase 5; MAP1LC3B: microtubule associated protein 1 light chain 3 beta; OCLN: occludin; PIK3C3: phosphatidylinositol 3-kinase catalytic subunit type 3; PIK3R4: phosphoinositide-3-kinase regulatory subunit 4; PNA: arachis hypogaea lectin; RAC1: Rac family small GTPase 1; SCIN: scinderin; SQSTM1/p62: sequestosome 1; SSC: spermatogonia stem cell; STK11: serine/threonine kinase 11; TJP1: tight junction protein 1; TubA: tubastatin A; TUBB3: tubulin beta 3 class III; TUNEL: TdT-mediated dUTP nick-end labeling; UB: ubiquitin; UVRAG: UV radiation resistance associated gene; VIM: vimentin; WT1: WT1 transcription factor; ZBTB16: zinc finger and BTB domain containing 16.
    Keywords:  Autophagy; F-actin; Sertoli cell; cell polarity; spermatogenesis
    DOI:  https://doi.org/10.1080/15548627.2023.2235195
  29. Nephron. 2023 Jul 13. 1-15
    The Interplay of Autophagy and Oxidative Stress in the Kidney: What Do We Know?
    Haihua Guo, Wibke Bechtel-Walz.
      BACKGROUND: Autophagy, as an indispensable metabolism, plays pivotal roles in maintaining intracellular homeostasis. Nutritional stress, amino acid deficiency, oxidative stress, and hypoxia can trigger its initiation. Oxidative stress in the kidney activates essential signal molecules, like mammalian target of rapamycin (mTOR), adenosine monophosphate-activated protein kinase (AMPK), and silent mating-type information regulation 2 homolog-1 (SIRT1), to stimulate autophagy, ultimately leading to degradation of intracellular oxidative substances and damaged organelles. Growing evidence suggests that autophagy protects the kidney from oxidative stress during acute ischemic kidney injury, chronic kidney disease, and even aging.SUMMARY: This review emphasizes the cross talk between reactive oxygen species (ROS) signaling pathways and autophagy during renal homeostasis and chronic kidney disease according to the current latest research and provides therapeutic targets during kidney disorders by adjusting autophagy and suppressing oxidative stress.
    KEY MESSAGES: ROS arise through an imbalance of oxidation and antioxidant defense mechanisms, leading to impaired cellular and organ function. Targeting the overproduction of ROS and reactive nitrogen species, reducing the antioxidant enzyme activity and the recovery of the prooxidative-antioxidative balance provide novel therapeutic regimens to contribute to recovery in acute and chronic renal failure. Although, in recent years, great progress has been made in understanding the molecular mechanisms of oxidative stress and autophagy in acute and chronic renal failure, the focus on clinical therapies is still in its infancy. The growing number of studies on the interactive mechanisms of oxidative stress-mediated autophagy will be of great importance for the future treatment and prevention of kidney diseases.
    Keywords:  Acute kidney injury; Autophagy; Chronic kidney disease; Oxidative stress; Reactive oxygen species
    DOI:  https://doi.org/10.1159/000531290
  30. Front Plant Sci. 2023 ;14 1018984
    Role of autophagy-related proteins ATG8f and ATG8h in the maintenance of autophagic activity in Arabidopsis roots under phosphate starvation.
    Li-Yen Lin, Hong-Xuan Chow, Chih-Hao Chen, Nobutaka Mitsuda, Wen-Chun Chou, Tzu-Yin Liu.
      Nutrient starvation-induced autophagy is a conserved process in eukaryotes. Plants defective in autophagy show hypersensitivity to carbon and nitrogen limitation. However, the role of autophagy in plant phosphate (Pi) starvation response is relatively less explored. Among the core autophagy-related (ATG) genes, ATG8 encodes a ubiquitin-like protein involved in autophagosome formation and selective cargo recruitment. The Arabidopsis thaliana ATG8 genes, AtATG8f and AtATG8h, are notably induced in roots under low Pi. In this study, we show that such upregulation correlates with their promoter activities and can be suppressed in the phosphate response 1 (phr1) mutant. Yeast one-hybrid analysis failed to attest the binding of the AtPHR1 transcription factor to the promoter regions of AtATG8f and AtATG8h. Dual luciferase reporter assays in Arabidopsis mesophyll protoplasts also indicated that AtPHR1 could not transactivate the expression of both genes. Loss of AtATG8f and AtATG8h leads to decreased root microsomal-enriched ATG8 but increased ATG8 lipidation. Moreover, atg8f/atg8h mutants exhibit reduced autophagic flux estimated by the vacuolar degradation of ATG8 in the Pi-limited root but maintain normal cellular Pi homeostasis with reduced number of lateral roots. While the expression patterns of AtATG8f and AtATG8h overlap in the root stele, AtATG8f is more strongly expressed in the root apex and root hair and remarkably at sites where lateral root primordia develop. We hypothesize that Pi starvation-induction of AtATG8f and AtATG8h may not directly contribute to Pi recycling but rely on a second wave of transcriptional activation triggered by PHR1 that fine-tunes cell type-specific autophagic activity.
    Keywords:  Arabidopsis; autophagy; autophagy-related protein 8 (ATG8); lateral root; phosphate starvation
    DOI:  https://doi.org/10.3389/fpls.2023.1018984
  31. Autophagy. 2023 Jul 12. 1-3
    Autophagy-ER stress crosstalk controls mucus secretion and susceptibility to gut inflammation.
    Maria Naama, Shai Bel.
      Mucus secretion from colonic goblet cells is an important host defense mechanism against the harsh lumenal environment. Yet how mucus secretion is regulated is not well understood. We discovered that constitutive activation of macroautophagy/autophagy via BECN1 (beclin 1) relieves endoplasmic reticulum (ER) stress in goblet cells, which in turn produce a thicker and less penetrable mucus barrier. Pharmacological reduction of the ER stress or activation of the unfolded protein response (UPR) in mice, regardless of autophagy activation, lead to excess mucus secretion. This regulation of mucus secretion by ER stress is microbiota-dependent and requires the activity of the intracellular sensor NOD2 (nucleotide-binding oligomerization domain containing 2). Excess mucus production in the colon alters the gut microbiota and protects from chemical- and infection-driven inflammation. Our findings provide new insights into the mechanisms by which autophagy regulates mucus secretion and susceptibility to intestinal inflammation.Abbreviations:BECN1- Beclin 1; ER- endoplasmic reticulum; UPR - unfolded protein response; NOD2 - nucleotide-binding oligomerization domain containing 2; IBD- inflammatory bowel disease; BCL2- B cell leukemia/lymphoma 2; TUDCA- tauroursodeoxycholic acid; ATG16L1- autophagy related 16 like 1; LRRK2- leucine-rich repeat kinase 2.
    Keywords:  Autophagy; BECN1; Crohn’s disease; ER stress; Goblet; Mucus
    DOI:  https://doi.org/10.1080/15548627.2023.2228191
  32. Nat Commun. 2023 07 12. 14(1): 4146
    A protein kinase coordinates cycles of autophagy and glutaminolysis in invasive hyphae of the fungus Magnaporthe oryzae within rice cells.
    Gang Li, Ziwen Gong, Nawaraj Dulal, Margarita Marroquin-Guzman, Raquel O Rocha, Michael Richter, Richard A Wilson.
      The blast fungus Magnaporthe oryzae produces invasive hyphae in living rice cells during early infection, separated from the host cytoplasm by plant-derived interfacial membranes. However, the mechanisms underpinning this intracellular biotrophic growth phase are poorly understood. Here, we show that the M. oryzae serine/threonine protein kinase Rim15 promotes biotrophic growth by coordinating cycles of autophagy and glutaminolysis in invasive hyphae. Alongside inducing autophagy, Rim15 phosphorylates NAD-dependent glutamate dehydrogenase, resulting in increased levels of α-ketoglutarate that reactivate target-of-rapamycin (TOR) kinase signaling, which inhibits autophagy. Deleting RIM15 attenuates invasive hyphal growth and triggers plant immunity; exogenous addition of α-ketoglutarate prevents these effects, while glucose addition only suppresses host defenses. Our results indicate that Rim15-dependent cycles of autophagic flux liberate α-ketoglutarate - via glutaminolysis - to reactivate TOR signaling and fuel biotrophic growth while conserving glucose for antioxidation-mediated host innate immunity suppression.
    DOI:  https://doi.org/10.1038/s41467-023-39880-w
  33. Int J Mol Sci. 2023 Jun 30. pii: 10944. [Epub ahead of print]24(13):
    Autophagy Regulators in Cancer.
    Juan Zhang, Qian Xiang, Man Wu, Yuan-Zhi Lao, Yan-Fang Xian, Hong-Xi Xu, Zhi-Xiu Lin.
      Autophagy plays a complex impact role in tumor initiation and development. It serves as a double-edged sword by supporting cell survival in certain situations while also triggering autophagic cell death in specific cellular contexts. Understanding the intricate functions and mechanisms of autophagy in tumors is crucial for guiding clinical approaches to cancer treatment. Recent studies highlight its significance in various aspects of cancer biology. Autophagy enables cancer cells to adapt to and survive unfavorable conditions by recycling cellular components. However, excessive or prolonged autophagy can lead to the self-destruction of cancer cells via a process known as autophagic cell death. Unraveling the molecular mechanisms underlying autophagy regulation in cancer is crucial for the development of targeted therapeutic interventions. In this review, we seek to present a comprehensive summary of current knowledge regarding autophagy, its impact on cancer cell survival and death, and the molecular mechanisms involved in the modulation of autophagy for cancer therapy.
    Keywords:  apoptosis; autophagy; cancer; cancer therapy; inducers; inhibitors; metastasis
    DOI:  https://doi.org/10.3390/ijms241310944
  34. Autophagy. 2023 Jul 11. 1-16
    ATG4B antagonizes antiviral immunity by GABARAP-directed autophagic degradation of TBK1.
    Weihong Xie, Chenqiu Zhang, Zheyu Wang, Hui Chen, Tonghui Gu, Tao Zhou, Yaoxing Wu, Fan Xia, Min Li, Jun Wang, Renjie Jiao, Jun Cui, Shouheng Jin.
      ABBREVIATIONS: Baf A1: bafilomycin A1; GABARAP: GABA type A receptor-associated protein; GFP: green fluorescent protein; IFN: interferon; IKBKE/IKKi: inhibitor of nuclear factor kappa B kinase subunit epsilon; IRF3: interferon regulatory factor 3; ISG: interferon-stimulated gene; ISRE: IFN-stimulated response element; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MAVS: mitochondrial antiviral signaling protein; MOI: multiplicity of infection; PAMPs: pathogen-associated molecule patterns; RIGI/DDX58: RNA sensor RIG-I; SeV: Sendai virus; siRNA: small interfering RNA; TBK1: TANK binding kinase 1; WT: wild-type; VSV: vesicular stomatitis virus.
    Keywords:  ATG4B; Antiviral immune response; LC3-interacting region; TBK1; selective autophagy
    DOI:  https://doi.org/10.1080/15548627.2023.2233846
  35. bioRxiv. 2023 Jun 29. pii: 2023.06.29.547095. [Epub ahead of print]
    A partial Drp1 knockout improves autophagy flux independent of mitochondrial function.
    Rebecca Z Fan, Carolina Sportelli, Yanhao Lai, Said Salehe, Jennifer R Pinnell, Jason R Richardson, Shouqing Luo, Kim Tieu.
      Dynamin-related protein 1 (Drp1) is typically known for its role in mitochondrial fission. A partial inhibition of this protein has been reported to be protective in experimental models of neurodegenerative diseases. The protective mechanism has been attributed primarily to improved mitochondrial function. Herein, we provide evidence showing that a partial Drp1-knockout improves autophagy flux independent of mitochondria. First, we characterized in cell and animal models that at low non-toxic concentrations, manganese (Mn), which causes parkinsonian-like symptoms in humans, impaired autophagy flux but not mitochondrial function and morphology. Furthermore, nigral dopaminergic neurons were more sensitive than their neighbouring GABAergic counterparts. Second, in cells with a partial Drp1-knockdown and Drp1 +/- mice, autophagy impairment induced by Mn was significantly attenuated. This study demonstrates that autophagy is a more vulnerable target than mitochondria to Mn toxicity. Furthermore, improving autophagy flux is a separate mechanism conferred by Drp1 inhibition independent of mitochondrial fission.
    DOI:  https://doi.org/10.1101/2023.06.29.547095
  36. Cancer Lett. 2023 Jul 12. pii: S0304-3835(23)00258-6. [Epub ahead of print] 216307
    Autophagy and cancer drug resistance in dialogue: Pre-clinical and clinical evidence.
    Yi Qin, Milad Ashrafizadeh, Vera Mongiardini, Benedetto Grimaldi, Francesco Crea, Katja Rietdorf, Balázs Győrffy, Daniel J Klionsky, Jun Ren, Wei Zhang, Xianbin Zhang.
      The emergence of drug resistance is a major challenge for oncologists. Resistance can be categorized as acquired or intrinsic; the alteration of several biological mechanisms contributes to both intrinsic and acquired resistance. Macroautophagy/autophagy is the primary process in eukaryotes for the degradation of macromolecules and organelles. This process is critical in maintaining cellular homeostasis. Given its function as either a pro-survival or a pro-death phenomenon, autophagy has a complex physio-pathological role. In some circumstances, autophagy can confer chemoresistance and promote cell survival, whereas in others it can promote chemosensitivity and contribute to cell death. The role of autophagy in the modulation of cancer drug resistance reflects its impact on apoptosis and metastasis. The regulation of autophagy in cancer is mediated by various factors including AMP-activated protein kinase (AMPK), MAPK, phosphoinositide 3-kinase (PI3K)-AKT, BECN1 and ATG proteins. Non-coding RNAs are among the main regulators of autophagy, e.g. via the modulation of chemoresistance pathways. Due to the significant contribution of autophagy in cancer drug resistance, small molecule modulators and natural compounds targeting autophagy have been introduced to alter the response of cancer cells to chemotherapy. Furthermore, nanotherapeutic approaches based on autophagy regulation have been introduced in pre-clinical cancer therapy. In this review we consider the potential for using autophagy regulators for the clinical treatment of malignancies.
    Keywords:  Apoptosis; Autophagy; Cancer drug resistance; Cell death; Chemoresistance; Drug sensitivity
    DOI:  https://doi.org/10.1016/j.canlet.2023.216307
  37. Autophagy. 2023 Jul 09. 1-3
    The autophagy-related protein ATG5 is a central mediator of a non-canonical autophagy pathway hijacked by HIV-1 to weaken the host's response to infection.
    Delphine Judith, Clarisse Berlioz-Torrent.
      Understanding how viruses evade innate defenses to efficiently spread in their hosts is crucial in the fight against infections. In our study, we provided new insights on the first step initiating an LC3C (microtubule associated protein 1 light chain 3 gamma)-associated degradative pathway exploited by HIV-1 (human immunodeficiency virus type 1) to overcome the antiviral action of the restriction factor BST2 (bone marrow stromal cell antigen 2)/tetherin. We have uncovered an unsuspected and unconventional function of the autophagy-related protein ATG5 in the recognition and engagement of BST2 molecules trapping viruses at the plasma membrane, and directing them toward this LC3C-associated pathway for degradation. Additionally, we highlighted that HIV-1 uses this LC3C-associated process to attenuate the inflammatory responses triggered by BST2-mediated sensing of viruses.
    Keywords:  ATG5; BST2; HIV-1; LC3C-associated pathway; Vpu; restriction factor
    DOI:  https://doi.org/10.1080/15548627.2023.2232225
  38. Arch Biochem Biophys. 2023 Jul 08. pii: S0003-9861(23)00188-1. [Epub ahead of print] 109689
    Exogenous galanin alleviates hepatic steatosis by promoting autophagy via the AMPK-mTOR pathway.
    Shuyuan Zhu, Shuai Wang, Tao Luo.
      Defective autophagy-induced intracellular lipid degradation is causally associated with non-alcoholic fatty liver disease (NAFLD) development. Therefore, agents that can restore autophagy may have potential clinical application prospects on this public health issue. Galanin (GAL) is a pleiotropic peptide that regulates autophagy and is a potential drug for the treatment of NAFLD. In this study, we used an MCD-induced NAFLD mouse model in vivo and an FFA-induced HepG2 hepatocyte model in vitro to evaluate the anti-NAFLD effect of GAL. Exogenous GAL supplementation significantly attenuated lipid droplet accumulation and suppressed hepatocyte TG levels in mice and cell models. Mechanistically, Galanin-mediated reduction of lipid accumulation was positively correlated with upregulated p-AMPK, as evidenced by upregulated protein expressions of fatty acid oxidation-related gene markers (PPAR-α and CPT1A), upregulated expressions of the autophagy-related marker (LC3B), and downregulated autophagic substrate p62 levels. In FFA-treated HepG2 cells, activation of fatty acid oxidation and autophagy-related proteins by galanin was reversed by autophagy inhibitors, chloroquine, and the AMPK inhibitor. Galanin ameliorates hepatic fat accumulation by inducing autophagy and fatty acid oxidation via the AMPK/mTOR pathway.
    Keywords:  AMPK; Autophagy; Galanin; NAFLD; β-Oxidation
    DOI:  https://doi.org/10.1016/j.abb.2023.109689
  39. Biol Res. 2023 Jul 13. 56(1): 41
    Hyperbaric oxygen treatment increases intestinal stem cell proliferation through the mTORC1/S6K1 signaling pathway in Mus musculus.
    Ignacio Casanova-Maldonado, David Arancibia, Pablo Lois, Isaac Peña-Villalobos, Verónica Palma.
      BACKGROUND: Hyperbaric oxygen treatment (HBOT) has been reported to modulate the proliferation of neural and mesenchymal stem cell populations, but the molecular mechanisms underlying these effects are not completely understood. In this study, we aimed to assess HBOT somatic stem cell modulation by evaluating the role of the mTOR complex 1 (mTORC1), a key regulator of cell metabolism whose activity is modified depending on oxygen levels, as a potential mediator of HBOT in murine intestinal stem cells (ISCs).RESULTS: We discovered that acute HBOT synchronously increases the proliferation of ISCs without affecting the animal's oxidative metabolism through activation of the mTORC1/S6K1 axis. mTORC1 inhibition by rapamycin administration for 20 days also increases ISCs proliferation, generating a paradoxical response in mice intestines, and has been proposed to mimic a partial starvation state. Interestingly, the combination of HBOT and rapamycin does not have a synergic effect, possibly due to their differential impact on the mTORC1/S6K1 axis.
    CONCLUSIONS: HBOT can induce an increase in ISCs proliferation along with other cell populations within the crypt through mTORC1/S6K1 modulation without altering the oxidative metabolism of the animal's small intestine. These results shed light on the molecular mechanisms underlying HBOT therapeutic action, laying the groundwork for future studies.
    Keywords:  Caloric restriction; Clarity; Hyperbaric oxygen treatment; Intestinal stem cells; Progenitor cells; Proliferation; Rapamycin; S6K1; mTORC1
    DOI:  https://doi.org/10.1186/s40659-023-00444-3
  40. Int J Mol Sci. 2023 Jun 28. pii: 10800. [Epub ahead of print]24(13):
    Vps4a Regulates Autophagic Flux to Prevent Hypertrophic Cardiomyopathy.
    Xiaozhi Huang, Jiayin Zhang, Wenyi Wang, Zhishan Huang, Peidong Han.
      Autophagy has stabilizing functions for cardiomyocytes. Recent studies indicate that an impairment in the autophagy pathway can seriously affect morphology and function, potentially leading to heart failure. However, the role and the underlying mechanism of the endosomal sorting complex required for transport (ESCRT) family protein, in particular the AAA-ATPase vacuolar protein sorting 4a (Vps4a), in regulating myocardial autophagy remains unclear. In the present study, cardiomyocyte-specific Vps4a knockout mice were generated by crossing Vps4aflox/flox (Vps4afl/fl) with Myh6-cre transgenic mice. As a result, we observed a partially dilated left ventricular (LV) chamber, a significant increase in heart weight to body weight ratio (HW/BW), and heart weight to tibial length ratio (HW/TL), hypertrophic cardiomyopathy and early lethality starting at 3 months of age. Hematoxylin-eosin (HE), immunofluorescence assay (IFA), and Western blot (WB) revealed autophagosome accumulation in cardiomyocytes. A transcriptome-based analysis and autophagic flux tracking by AAV-RFP-GFP-LC3 showed that the autophagic flux was blocked in Vps4a knockout cardiomyocytes. In addition, we provided in vitro evidence demonstrating that Vps4a and LC3 were partially co-localized in cardiomyocytes, and the knockdown of Vps4a led to the accumulation of autophagosomes in cardiomyocytes. Similarly, the transfection of cardiomyocytes with adenovirus (Adv) mCherry-GFP-LC3 further indicated that the autophagic flux was blocked in cells with deficient levels of Vps4a. Finally, an electron microscope (EM) showed that the compromised sealing of autophagosome blocked the autophagic flux in Vps4a-depleted cardiomyocytes. These findings revealed that Vps4a contributed to the sealing of autophagosomes in cardiomyocytes. Therefore, we demonstrated that Vps4a deletion could block the autophagic flux, leading to the accumulation of degradation substances and compromised cardiac function. Overall, this study provides insights into a new theoretical basis for which autophagy may represent a therapeutic target for cardiovascular diseases.
    Keywords:  ESCRT; Vps4a; autophagy; heart; heart failure
    DOI:  https://doi.org/10.3390/ijms241310800
  41. Autophagy Rep. 2022 ;1(1): 438-515
    Interactions of Autophagy and the Immune System in Health and Diseases.
    Aarti Pant, Xiaomin Yao, Aude Lavedrine, Christophe Viret, Jake Dockterman, Swati Chauhan, Chong-Shan Shi, Ravi Manjithaya, Ken Cadwell, Thomas A Kufer, John H Kehrl, Jörn Coers, L David Sibley, Mathias Faure, Gregory A Taylor, Santosh Chauhan.
      Autophagy is a highly conserved process that utilizes lysosomes to selectively degrade a variety of intracellular cargo, thus providing quality control over cellular components and maintaining cellular regulatory functions. Autophagy is triggered by multiple stimuli ranging from nutrient starvation to microbial infection. Autophagy extensively shapes and modulates the inflammatory response, the concerted action of immune cells, and secreted mediators aimed to eradicate a microbial infection or to heal sterile tissue damage. Here, we first review how autophagy affects innate immune signaling, cell-autonomous immune defense, and adaptive immunity. Then, we discuss the role of non-canonical autophagy in microbial infections and inflammation. Finally, we review how crosstalk between autophagy and inflammation influences infectious, metabolic, and autoimmune disorders.
    DOI:  https://doi.org/10.1080/27694127.2022.2119743
  42. Acta Pharm Sin B. 2023 Jun;13(6): 2701-2714
    Corynoxine B targets at HMGB1/2 to enhance autophagy for α-synuclein clearance in fly and rodent models of Parkinson's disease.
    Qi Zhu, Juxian Song, Jia-Yue Chen, Zhenwei Yuan, Liangfeng Liu, Li-Ming Xie, Qiwen Liao, Richard D Ye, Xiu Chen, Yepiao Yan, Jieqiong Tan, Chris Soon Heng Tan, Min Li, Jia-Hong Lu.
      Parkinson's disease (PD) is the most common neurodegenerative movement disease. It is featured by abnormal alpha-synuclein (α-syn) aggregation in dopaminergic neurons in the substantia nigra. Macroautophagy (autophagy) is an evolutionarily conserved cellular process for degradation of cellular contents, including protein aggregates, to maintain cellular homeostasis. Corynoxine B (Cory B), a natural alkaloid isolated from Uncaria rhynchophylla (Miq.) Jacks., has been reported to promote the clearance of α-syn in cell models by inducing autophagy. However, the molecular mechanism by which Cory B induces autophagy is not known, and the α-syn-lowering activity of Cory B has not been verified in animal models. Here, we report that Cory B enhanced the activity of Beclin 1/VPS34 complex and increased autophagy by promoting the interaction between Beclin 1 and HMGB1/2. Depletion of HMGB1/2 impaired Cory B-induced autophagy. We showed for the first time that, similar to HMGB1, HMGB2 is also required for autophagy and depletion of HMGB2 decreased autophagy levels and phosphatidylinositol 3-kinase III activity both under basal and stimulated conditions. By applying cellular thermal shift assay, surface plasmon resonance, and molecular docking, we confirmed that Cory B directly binds to HMGB1/2 near the C106 site. Furthermore, in vivo studies with a wild-type α-syn transgenic drosophila model of PD and an A53T α-syn transgenic mouse model of PD, Cory B enhanced autophagy, promoted α-syn clearance and improved behavioral abnormalities. Taken together, the results of this study reveal that Cory B enhances phosphatidylinositol 3-kinase III activity/autophagy by binding to HMGB1/2 and that this enhancement is neuroprotective against PD.
    Keywords:  Autophagy; Corynoxine B; HMGB1; HMGB2; Neurodegenerative disease; PI3KC3; Parkinson's disease; α-Synuclein
    DOI:  https://doi.org/10.1016/j.apsb.2023.03.011
  43. Int J Biochem Cell Biol. 2023 Jul 08. pii: S1357-2725(23)00078-X. [Epub ahead of print] 106439
    hsa-miR-320a mediated exosome release under PD stress conditions rescue mitochondrial ROS and cell death in the recipient neuronal and glial cells.
    Shatakshi Shukla, Fatema Currim, Jyoti Singh, Shanikumar Goyani, M V Saranga, Anjali Shinde, Minal Mane, Nisha Chandak, Shyam Kishore, Rajesh Singh.
      Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by dopaminergic neuronal cell death. Emerging evidence suggest exosomes as a crucial player in the progression and pathogenesis of PD via intercellular communication between different cell types in brain. Exosome release is enhanced from dysfunctional neurons/glia (source cells) under PD stress and mediates the transfer of biomolecules between different cell types (recipient) in brain leading to unique functional outcomes. Exosome release is modulated by alterations in the autophagy and lysosomal pathways; however, the molecular factors regulating these pathways remain elusive. Micro-RNAs (miRNAs) are class of non-coding RNAs that regulate gene expression post-transcriptionally by binding target mRNA and modulate its turnover and translation; however their role in modulating exosome release is not understood. Here, we analyzed the miRNAs-mRNAs network which target cellular processes regulating exosome release. hsa-miR-320a showed the maximum mRNA targets of autophagy, lysosome, mitochondria and exosome release pathways. hsa-miR-320a regulate ATG5 levels and modulate exosome release under PD stress conditions in neuronal SH-SY5Y and glial U-87 MG cells. hsa-miR-320a modulates autophagic flux, lysosomal functions, and mitochondrial ROS in neuronal SH-SY5Y and glial U-87 MG cells. Exosomes derived from hsa-miR-320a expressing source cells under PD stress conditions were actively internalized in the recipient cells and rescued cell death and mitochondrial ROS. These results suggest that hsa-miR-320a regulates autophagy and lysosomal pathways and modulates exosome release in the source cells and derived exosomes under PD stress conditions rescue cell death and mitochondrial ROS in the recipient neuronal and glial cells.
    Keywords:  Parkinson’s disease; autophagy; cell-death; exosomes; hsa-miR-320a; lysosome; mitochondria
    DOI:  https://doi.org/10.1016/j.biocel.2023.106439
  44. mBio. 2023 Jul 12. e0102023
    Bidirectional interplay between SARS-CoV-2 and autophagy.
    Hao Zhou, Zhiqiang Hu, Sergio Castro-Gonzalez.
      Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), as the causative agent of the recent COVID-19 pandemic, continues representing one of the main health concerns worldwide. Autophagy, in addition to its role in cellular homeostasis and metabolism, plays an important part for the host antiviral immunity. However, viruses including SARS-CoV-2 have evolved diverse mechanisms to not only overcome autophagy's antiviral pressure but also manipulate its machinery in order to enhance viral replication and propagation. Here, we discuss our current knowledge on the impact that autophagy exerts on SARS-CoV-2 replication, as well as the different counteracting measures that this virus has developed to manipulate autophagy's complex machinery. Some of the elements regarding this interplay may become future therapeutic targets in the fight against SARS-CoV-2.
    Keywords:  COVID-19; SARS-CoV-2; autophagy; innate immunity; therapeutic targets
    DOI:  https://doi.org/10.1128/mbio.01020-23
  45. Cell Death Dis. 2023 Jul 08. 14(7): 409
    Crosstalk between autophagy and CSCs: molecular mechanisms and translational implications.
    Dai Li, Xueqiang Peng, Guangpeng He, Jiaxing Liu, Xian Li, Weikai Lin, Jianjun Fang, Xinyu Li, Shuo Yang, Liang Yang, Hangyu Li.
      Cancer stem cells(CSCs) play a key role in regulating tumorigenesis, progression, as well as recurrence, and possess typical metabolic characteristics. Autophagy is a catabolic process that can aid cells to survive under stressful conditions such as nutrient deficiency and hypoxia. Although the role of autophagy in cancer cells has been extensively studied, CSCs possess unique stemness, and their potential relationship with autophagy has not been fully analyzed. This study summarizes the possible role of autophagy in the renewal, proliferation, differentiation, survival, metastasis, invasion, and treatment resistance of CSCs. It has been found that autophagy can contribute to the maintenance of CSC stemness, facilitate the tumor cells adapt to changes in the microenvironment, and promote tumor survival, whereas in some other cases autophagy acts as an important process involved in the deprivation of CSC stemness thus leading to tumor death. Mitophagy, which has emerged as another popular research area in recent years, has a great scope when explored together with stem cells. In this study, we have aimed to elaborate on the mechanism of action of autophagy in regulating the functions of CSCs to provide deeper insights for future cancer treatment.
    DOI:  https://doi.org/10.1038/s41419-023-05929-3
  46. Nat Commun. 2023 07 11. 14(1): 4105
    Hypoxia-reprogramed megamitochondrion contacts and engulfs lysosome to mediate mitochondrial self-digestion.
    Tianshu Hao, Jianglong Yu, Zhida Wu, Jie Jiang, Longlong Gong, Bingjun Wang, Hanze Guo, Huabin Zhao, Bin Lu, Simone Engelender, He He, Zhiyin Song.
      Mitochondria are the key organelles for sensing oxygen, which is consumed by oxidative phosphorylation to generate ATP. Lysosomes contain hydrolytic enzymes that degrade misfolded proteins and damaged organelles to maintain cellular homeostasis. Mitochondria physically and functionally interact with lysosomes to regulate cellular metabolism. However, the mode and biological functions of mitochondria-lysosome communication remain largely unknown. Here, we show that hypoxia remodels normal tubular mitochondria into megamitochondria by inducing broad inter-mitochondria contacts and subsequent fusion. Importantly, under hypoxia, mitochondria-lysosome contacts are promoted, and certain lysosomes are engulfed by megamitochondria, in a process we term megamitochondria engulfing lysosome (MMEL). Both megamitochondria and mature lysosomes are required for MMEL. Moreover, the STX17-SNAP29-VAMP7 complex contributes to mitochondria-lysosome contacts and MMEL under hypoxia. Intriguingly, MMEL mediates a mode of mitochondrial degradation, which we termed mitochondrial self-digestion (MSD). Moreover, MSD increases mitochondrial ROS production. Our results reveal a mode of crosstalk between mitochondria and lysosomes and uncover an additional pathway for mitochondrial degradation.
    DOI:  https://doi.org/10.1038/s41467-023-39811-9
  47. Anim Biotechnol. 2023 Jul 12. 1-11
    Glucose promotes cell growth and casein synthesis via ATF4/Nrf2-Sestrin2- AMPK-mTORC1 pathway in dairy cow mammary epithelial cells.
    Wei Yu, Jinqi Guo, Lei Mao, Qingzhu Wang, Yuanyuan Liu, Dong Xu, Jiage Ma, Chaochao Luo.
      In the dairy industry, glucose (Glu) is used as bioactive substance to increase milk yield. However, the molecular regulation underneath needs further clarification. Here, the regulation and its molecular mechanism of Glu on cell growth and casein synthesis of dairy cow mammary epithelial cells (DCMECs) were investigated. When Glu was added from DCMECs, both cell growth, β-casein expression and the mechanistic target of rapamycin complex 1 (mTORC1) pathway were increased. Overexpression and silencing of mTOR revealed that Glu promoted cell growth and β-casein expression through the mTORC1 pathway. When Glu was added from DCMECs, both Adenosine 5'-monophosphate-activated protein kinase α (AMPKα) and Sestrin2 (SESN2) expression were decreased. Overexpression and silencing of AMPKα or SESN2 uncovered that AMPKα suppressed cell growth and β-casein synthesis through inhibiting mTORC1 pathway, and SESN2 suppressed cell growth and β-casein synthesis through activating AMPK pathway. When Glu was depleted from DCMECs, both activating transcription factor 4 (ATF4) and nuclear factor (erythroid-derived 2)-like 2 (Nrf2) expression were increased. Overexpression or silencing of ATF4 or Nrf2 demonstrated that Glu depletion promoted SESN2 expression through ATF4 and Nrf2. Together, these results indicate that in DCMECs, Glu promoted cell growth and casein synthesis via ATF4/Nrf2-SESN2-AMPK-mTORC1 pathway.
    Keywords:  ATF4/Nrf2-Sestrin2-AMPK-mTORC1 pathway; Glucose; casein synthesis; cell growth; dairy cow mammary epithelial cells
    DOI:  https://doi.org/10.1080/10495398.2023.2228847
  48. J Ovarian Res. 2023 Jul 11. 16(1): 137
    Lysophosphatidic acid is associated with oocyte maturation by enhancing autophagy via PI3K-AKT-mTOR signaling pathway in granulosa cells.
    Jia Liu, Chong Wang.
      BACKGROUND: Folliculogenesis is a complex network of interacting cellular signals between somatic cells and oocytes. Many components in ovarian follicular fluid (FF) dynamically change during folliculogenesis and play a positive role in oocyte maturation. Previous studies have reported that lysophosphatidic acid (LPA) promotes cumulus cell expansion, oocyte nuclear maturation, and in vitro maturation of oocytes.RESULTS: Initially, the expression of LPA was raised in matured FF significantly (P < 0.0001). Then, 10 μM LPA treated for 24 h in human granulosa cells (KGNs) aggravated cell proliferation, with increased autophagy, and reduced apoptosis. Meanwhile, we demonstrated that LPA mediated cell function through the PI3K-AKT-mTOR signaling pathway as PI3K inhibitor (LY294002) significantly prevented LPA-induced AKT, mTOR phosphorylation and autophagy activation. Such results were also verified by immunofluorescence staining and flow cytometry. In addition, an autophagy inhibitor 3 methyladenine (3MA) could also alleviate the effects of LPA, by activating apoptosis through PI3K-AKT-mTOR pathways. Finally, we found blockade with Ki16425 or knockdown LPAR1, alleviated LPA mediated autophagy activation in KGNs, suggesting that LPA enhances autophagy through activation of the LPAR1 and PI3K-AKT-mTOR signaling pathways.
    CONCLUSION: This study demonstrates that increased LPA activated PI3K-Akt-mTOR pathway through LPAR1 in granulosa cells, suppressing apoptosis by enhancing autophagy, which might play a role in oocyte maturation in vivo.
    Keywords:  Autophagy; Granulosa cells; In vitro maturation; LY294002; Lysophosphatidic acid; Small interfering RNA
    DOI:  https://doi.org/10.1186/s13048-023-01228-9
  49. Cell Stress. 2023 Jul;7(7): 50-58
    Molecular targets of spermidine: implications for cancer suppression.
    Andreas Zimmermann, Sebastian J Hofer, Frank Madeo.
      Spermidine is a ubiquitous, natural polyamine with geroprotective features. Supplementation of spermidine extends the lifespan of yeast, worms, flies, and mice, and dietary spermidine intake correlates with reduced human mortality. However, the crucial role of polyamines in cell proliferation has also implicated polyamine metabolism in neoplastic diseases, such as cancer. While depleting intracellular polyamine biosynthesis halts tumor growth in mouse models, lifelong external spermidine administration in mice does not increase cancer incidence. In contrast, a series of recent findings points to anti-neoplastic properties of spermidine administration in the context of immunotherapy. Various molecular mechanisms for the anti-aging and anti-cancer properties have been proposed, including the promotion of autophagy, enhanced translational control, and augmented mitochondrial function. For instance, spermidine allosterically activates mitochondrial trifunctional protein (MTP), a bipartite protein complex that mediates three of the four steps of mitochondrial fatty acid (β-oxidation. Through this action, spermidine supplementation is able to restore MTP-mediated mitochondrial respiratory capacity in naïve CD8+ T cells to juvenile levels and thereby improves T cell activation in aged mice. Here, we put this finding into the context of the previously described molecular target space of spermidine.
    Keywords:  autophagy; cancer; hypusination; immunosurveillance; molecular targets; spermidine
    DOI:  https://doi.org/10.15698/cst2023.07.281
  50. Cell Rep. 2023 Jul 11. pii: S2211-1247(23)00801-X. [Epub ahead of print]42(7): 112790
    SREBP-1 upregulates lipophagy to maintain cholesterol homeostasis in brain tumor cells.
    Feng Geng, Yaogang Zhong, Huali Su, Etienne Lefai, Shino Magaki, Timothy F Cloughesy, William H Yong, Arnab Chakravarti, Deliang Guo.
      Cholesterol is a structural component of cell membranes. How rapidly growing tumor cells maintain membrane cholesterol homeostasis is poorly understood. Here, we found that glioblastoma (GBM), the most lethal brain tumor, maintains normal levels of membrane cholesterol but with an abundant presence of cholesteryl esters (CEs) in its lipid droplets (LDs). Mechanistically, SREBP-1 (sterol regulatory element-binding protein 1), a master transcription factor that is activated upon cholesterol depletion, upregulates critical autophagic genes, including ATG9B, ATG4A, and LC3B, as well as lysosome cholesterol transporter NPC2. This upregulation promotes LD lipophagy, resulting in the hydrolysis of CEs and the liberation of cholesterol from the lysosomes, thus maintaining plasma membrane cholesterol homeostasis. When this pathway is blocked, GBM cells become quite sensitive to cholesterol deficiency with poor growth in vitro. Our study unravels an SREBP-1-autophagy-LD-CE hydrolysis pathway that plays an important role in maintaining membrane cholesterol homeostasis while providing a potential therapeutic avenue for GBM.
    Keywords:  ATG4A; ATG9B; CP: Cancer; CP: Metabolism; LC3B; NPC2; SREBP-1; autophagy; cholesterol homeostasis; cholesteryl esters; glioblastoma; lipid droplets
    DOI:  https://doi.org/10.1016/j.celrep.2023.112790
  51. Chem Biol Interact. 2023 Jul 11. pii: S0009-2797(23)00296-X. [Epub ahead of print] 110629
    Swainsonine inhibits autophagic degradation and causes cytotoxicity by reducing CTSD O-GlcNAcylation.
    Shuai Wang, Panpan Tan, Hongwei Wang, Jicang Wang, Cai Zhang, Hao Lu, Baoyu Zhao.
      Swainsonine (SW) is the primary toxin in locoweed, a poisonous plant. SW can cause animal poisoning, affect the quality and safety of meat products and threaten human health, but the mechanism of its toxicity is little defined. Here, we identified 159 differentially expressed proteins, many of which are involved in autophagy and glycosylation modification processes, using proteomics sequencing analysis. O-linked-N-acetylglucosamylation (O-GlcNAcylation) is a glycosylation modification widely involved in various biological processes. Our results show that SW toxicity is related to O-GlcNAcylation. In addition, increased O-GlcNAcylation with the O-GlcNAcase (OGA) inhibitor TMG promoted autophagy, while decreased O-GlcNAcylation with the O-GlcNAc transferase (OGT) inhibitor OSMI inhibited autophagy. Further analysis by Immunoprecipitation (IP) showed that SW could change the O-GlcNAcylation of Cathepsin D (CTSD), reducing the expression of mature CTSD (m-CTSD). In summary, these findings suggest that SW inhibits the O-GlcNAcylation of CTSD, affecting its maturation and leading to the impairment of lysosome function. Consequently, it inhibits autophagy degradation, and causes cytotoxicity, providing a new theoretical basis for SW toxicological mechanism.
    Keywords:  Autophagy; CTSD; O-GlcNAcylation; Swainsonine; Toxicity
    DOI:  https://doi.org/10.1016/j.cbi.2023.110629
  52. Eur J Pharmacol. 2023 Jul 08. pii: S0014-2999(23)00370-9. [Epub ahead of print]955 175859
    Role of autophagy in the pathogenesis and regulation of pain.
    Guangda Zheng, Juanxia Ren, Lu Shang, Yanju Bao.
      Pain is a ubiquitous and highly concerned clinical symptom, usually caused by peripheral or central nervous injury, tissue damage, or other diseases. The long-term existence of pain can seriously affect daily physical function and quality of life and produce great torture on the physiological and psychological levels. However, the complex pathogenesis of pain involving molecular mechanisms and signaling pathways has not been fully elucidated, and managing pain remains highly challenging. As a result, finding new targets to pursue effective and long-term pain treatment strategies is required and urgent. Autophagy is an intracellular degradation and recycling process that maintains tissue homeostasis and energy supply, which can be cytoprotective and is vital in maintaining neural plasticity and proper nervous system function. Much evidence has shown that autophagy dysregulation is linked to the emergence of neuropathic pain, such as postherpetic neuralgia and cancer-related pain. Autophagy has also been connected to pain caused by osteoarthritis and lumbar disc degeneration. It is worth noting that in recent years, studies on traditional Chinese medicine have also proved that several traditional Chinese medicine monomers involve autophagy in the mechanism of pain relief. Therefore, autophagy can serve as a potential regulatory target to provide new ideas and inspiration for pain management.
    Keywords:  Autophagy; Cancer-related pain; Neuropathic pain; Postherpetic neuralgia
    DOI:  https://doi.org/10.1016/j.ejphar.2023.175859
  53. Cell Discov. 2023 Jul 11. 9(1): 71
    Glc7/PP1 dephosphorylates histone H3T11 to regulate autophagy and telomere silencing in response to nutrient availability.
    Xinyu Zhang, Qi Yu, Yinsheng Wu, Yuan Zhang, Yi He, Rongsha Wang, Xilan Yu, Shanshan Li.
      How cells adapt their gene expression to nutritional changes remains poorly understood. Histone H3T11 is phosphorylated by pyruvate kinase to repress gene transcription. Here, we identify the protein phosphatase 1 (PP1), Glc7 as the enzyme that specifically dephosphorylates H3T11. We also characterize two novel Glc7-containing complexes and reveal their roles in regulating gene expression upon glucose starvation. Specifically, the Glc7-Sen1 complex dephosphorylates H3T11 to activate the transcription of autophagy-related genes. The Glc7-Rif1-Rap1 complex dephosphorylates H3T11 to derepress the transcription of telomere-proximal genes. Upon glucose starvation, Glc7 expression is up-regulated and more Glc7 translocates into the nucleus to dephosphorylate H3T11, leading to induction of autophagy and derepressed transcription of telomere-proximal genes. Furthermore, the functions of PP1/Glc7 and the two Glc7-containing complexes are conserved in mammals to regulate autophagy and telomere structure. Collectively, our results reveal a novel mechanism that regulate gene expression and chromatin structure in response to glucose availability.
    DOI:  https://doi.org/10.1038/s41421-023-00551-1
  54. Prog Neuropsychopharmacol Biol Psychiatry. 2023 Jul 11. pii: S0278-5846(23)00108-2. [Epub ahead of print] 110822
    Recency memory is altered in cocaine-withdrawn adolescent rats: Implication of cortical mTOR signaling.
    Fernando Castillo Díaz, Francesca Mottarlini, Giorgia Targa, Beatrice Rizzi, Fabio Fumagalli, Lucia Caffino.
      In humans, cocaine abuse during adolescence poses a significant risk for developing cognitive deficits later in life. Among the regions responsible for cognitive processes, the medial prefrontal cortex (mPFC) modulates temporal order information via mechanisms involving the mammalian-target of rapamycin (mTOR)-mediated pathway and protein synthesis regulation. Accordingly, our goal was to study the effect of repeated cocaine exposure during both adolescence and adulthood on temporal memory by studying the mTOR pathway in the mPFC. Adolescent or adult rats underwent repeated cocaine injections for 15 days and, after two weeks of withdrawal, engaged in the temporal order object recognition (TOOR) test. We found that repeated cocaine exposure during adolescence impaired TOOR performance, while control or adult-treated animals showed no impairments. Moreover, activation of the mTOR-S6-eEF2 pathway following the TOOR test was diminished only in the adolescent cocaine-treated group. Notably, inhibition of the mTOR-mediated pathway by rapamycin injection impaired TOOR performance in naïve adolescent and adult animals, revealing this pathway to be a critical component in regulating recency memory. Our data indicate that withdrawal from cocaine exposure impairs recency memory via the dysregulation of protein translation mechanisms, but only when cocaine is administered during adolescence.
    Keywords:  Adolescence; Cocaine; Prefrontal cortex; Rapamycin; Temporal order memory; mTOR
    DOI:  https://doi.org/10.1016/j.pnpbp.2023.110822
  55. Mol Neurobiol. 2023 Jul 10.
    Proteasomal Stimulation by MK886 and Its Derivatives Can Rescue Tau-Induced Neurite Pathology.
    Elly E Liao, Mu Yang, Noah Nathan Kochen, Nagamani Vunnam, Anthony R Braun, David M Ferguson, Jonathan N Sachs.
      Proteasomal degradation of intrinsically disordered proteins, such as tau, is a critical component of proteostasis in both aging and neurodegenerative diseases. In this study, we investigated proteasomal activation by MK886 (MK). We previously identified MK as a lead compound capable of modulating tau oligomerization in a cellular FRET assay and rescuing P301L tau-induced cytotoxicity. We first confirmed robust proteasomal activation by MK using 20S proteasomal assays and a cellular proteasomal tau-GFP cleavage assay. We then show that MK treatment can significantly rescue tau-induced neurite pathology in differentiated SHSY5Y neurospheres. Due to this compelling result, we designed a series of seven MK analogs to determine if proteasomal activity is sensitive to structural permutations. Using the proteasome as the primary MOA, we examined tau aggregation, neurite outgrowth, inflammation, and autophagy assays to identify two essential substituents of MK that are required for compound activity: (1) removal of the N-chlorobenzyl group from MK negated both proteasomal and autophagic activity and reduced neurite outgrowth; and (2) removal of the indole-5-isopropyl group significantly improved neurite outgrowth and autophagy activity but reduced its anti-inflammatory capacity. Overall, our results suggest that the combination of proteasomal/autophagic stimulation and anti-inflammatory properties of MK and its derivatives can decrease tau-tau interactions and help rebalance dysfunctional proteostasis. Further development of MK to optimize its proteasomal, autophagic, and anti-inflammatory targets may lead to a novel therapeutic that would be beneficial in aging and neurodegenerative diseases.
    Keywords:  Drug discovery; FRET; Neurite outgrowth; Proteasome; Proteostasis; Tau
    DOI:  https://doi.org/10.1007/s12035-023-03417-5
  56. Mitochondrion. 2023 Jul 12. pii: S1567-7249(23)00066-1. [Epub ahead of print]
    Mitochondrial Dysfunction and Skeletal Muscle Atrophy: Causes, Mechanisms, and Treatment Strategies.
    Gokhan Burcin Kubat, Esmaa Bouhamida, Oner Ulger, Ibrahim Turkel, Gaia Pedriali, Daniela Ramaccini, Ozgur Ekinci, Berkay Ozerklig, Ozbeyen Atalay, Simone Patergnani, Beyza Nur Sahin, Giampaolo Morciano, Meltem Tuncer, Elena Tremoli, Paolo Pinton.
      Skeletal muscle, which accounts for approximately 40% of total body weight, is one of the most dynamic and plastic tissues in the human body and plays a vital role in movement, posture and force production. More than just a component of the locomotor system, skeletal muscle functions as an endocrine organ capable of producing and secreting hundreds of bioactive molecules. Therefore, maintaining healthy skeletal muscles is crucial for supporting overall body health. Various pathological conditions, such as prolonged immobilization, cachexia, aging, drug-induced toxicity, and cardiovascular diseases (CVDs), can disrupt the balance between muscle protein synthesis and degradation, leading to skeletal muscle atrophy. Mitochondrial dysfunction is a major contributing mechanism to skeletal muscle atrophy, as it plays crucial roles in various biological processes, including energy production, metabolic flexibility, maintenance of redox homeostasis, and regulation of apoptosis. In this review, we critically examine recent knowledge regarding the causes of muscle atrophy (disuse, cachexia, aging, etc.) and its contribution to CVDs. Additionally, we highlight the mitochondrial signaling pathways involvement to skeletal muscle atrophy, such as the ubiquitin-proteasome system, autophagy and mitophagy, mitochondrial fission-fusion, and mitochondrial biogenesis. Furthermore, we discuss current strategies, including exercise, mitochondria-targeted antioxidants, in vivo transfection of PGC-1α, and the potential use of mitochondrial transplantation as a possible therapeutic approach.
    Keywords:  Skeletal muscle atrophy; cardiovascular diseases; exercise; mitochondria; mitochondrial transplantation
    DOI:  https://doi.org/10.1016/j.mito.2023.07.003
  57. Sci Rep. 2023 Jul 14. 13(1): 11414
    Longitudinal in vivo metabolic labeling reveals tissue-specific mitochondrial proteome turnover rates and proteins selectively altered by parkin deficiency.
    K L Stauch, S Totusek, A J Trease, L D Estrella, K Emanuel, A Fangmeier, H S Fox.
      Our study utilizes a longitudinal isotopic metabolic labeling approach in vivo in combination with organelle fraction proteomics to address the role of parkin in mitochondrial protein turnover in mice. The use of metabolic labeling provides a method to quantitatively determine the global changes in protein half-lives whilst simultaneously assessing protein expression. Studying two diverse mitochondrial populations, we demonstrated the median half-life of brain striatal synaptic mitochondrial proteins is significantly greater than that of hepatic mitochondrial proteins (25.7 vs. 3.5 days). Furthermore, loss of parkin resulted in an overall, albeit modest, increase in both mitochondrial protein abundance and half-life. Pathway and functional analysis of our proteomics data identified both known and novel pathways affected by loss of parkin that are consistent with its role in both mitochondrial quality control and neurodegeneration. Our study therefore adds to a growing body of evidence suggesting dependence on parkin is low for basal mitophagy in vivo and provides a foundation for the investigation of novel parkin targets.
    DOI:  https://doi.org/10.1038/s41598-023-38484-0
  58. J Nutr Biochem. 2023 Jul 07. pii: S0955-2863(23)00147-X. [Epub ahead of print] 109414
    Quercetin ameliorates non-alcoholic fatty liver disease (NAFLD) via the promotion of AMPK-mediated hepatic mitophagy.
    Peng Cao, Yi Wang, Cong Zhang, Mitchell A Sullivan, Wen Chen, Xiang Jing, Huifan Yu, Fei Li, Qu Wang, Zhongshi Zhou, Qi Wang, Wen Tian, Zhenpeng Qiu, Lianxiang Luo.
      BACKGROUND: The global incidence of non-alcoholic fatty liver disease (NAFLD) has been surging in recent years, however, no drug is currently approved to treat this disease.PURPOSE: Quercetin, a natural flavonoid abundant in plants and fruits, has been reported to alleviate NAFLD, however, the exact molecular mechanism remains unclear. This study aims to further elucidate its potential mechanism of action.
    METHODS: The beneficial effects and the underlying mechanism of quercetin in alleviating NAFLD were explored both in vitro and in vivo, by employing chemical inhibitors of autophagosomes (3-methyladenine, 3-MA), autolysosomes (chloroquine, CQ), AMPK (Compound C, CC) and SIRT1 (selisistat, EX-527). The levels of intracellular lipids, reactive oxygen species, mitochondria function, autophagy and mitophagy were assessed by fluorescent labeling and examined using flow cytometry or confocal microscopy. Key protein expressions of autophagy, mitophagy and inflammation were also determined.
    RESULTS: In vivo, quercetin was shown to dose-dependently effectively alleviate NAFLD, but intraperitoneal injection of 3-MA could block the beneficial effects of quercetin on body weight, liver weight, serum ALT/AST, hepatic ROS and inflammation. In vitro, quercetin could reduce intracellular lipids (Nile Red staining) and ROS/DHE accumulation, which could be also blocked by 3-MA or CQ. Furthermore, we found that CC could abrogate the protective effects of quercetin on lipid and ROS accumulation in vitro. Also, CC abolished the pro-autophagic and anti-inflammatory effects of quercetin, as shown by western blot determination and Lyso-Tracker labeling. Importantly, mitophagy, a specific form of mitochondria-targeted autophagy, was enhanced by quercetin, as demonstrated by PINK1/Parkin protein variation and immunofluorescence co-localization of autophagosomes and mitochondria, which could also be blocked by the intervention of CC.
    CONCLUSIONS: This study demonstrates that quercetin prevents NAFLD through AMPK-mediated mitophagy and suggests that promoting mitophagy via an upregulation of AMPK may be a promising therapeutic strategy against NAFLD.
    Keywords:  AMPK; NAFLD; autophagy; mitophagy; quercetin
    DOI:  https://doi.org/10.1016/j.jnutbio.2023.109414
  59. PLoS Genet. 2023 Jul 13. 19(7): e1010828
    Loss of STING in parkin mutant flies suppresses muscle defects and mitochondria damage.
    Andrew T Moehlman, Gil Kanfer, Richard J Youle.
      The early pathogenesis and underlying molecular causes of motor neuron degeneration in Parkinson's Disease (PD) remains unresolved. In the model organism Drosophila melanogaster, loss of the early-onset PD gene parkin (the ortholog of human PRKN) results in impaired climbing ability, damage to the indirect flight muscles, and mitochondrial fragmentation with swelling. These stressed mitochondria have been proposed to activate innate immune pathways through release of damage associated molecular patterns (DAMPs). Parkin-mediated mitophagy is hypothesized to suppress mitochondrial damage and subsequent activation of the cGAS/STING innate immunity pathway, but the relevance of this interaction in the fly remains unresolved. Using a combination of genetics, immunoassays, and RNA sequencing, we investigated a potential role for STING in the onset of parkin-null phenotypes. Our findings demonstrate that loss of Drosophila STING in flies rescues the thorax muscle defects and the climbing ability of parkin-/- mutants. Loss of STING also suppresses the disrupted mitochondrial morphology in parkin-/- flight muscles, suggesting unexpected feedback of STING on mitochondria integrity or activation of a compensatory mitochondrial pathway. In the animals lacking both parkin and sting, PINK1 is activated and cell death pathways are suppressed. These findings support a unique, non-canonical role for Drosophila STING in the cellular and organismal response to mitochondria stress.
    DOI:  https://doi.org/10.1371/journal.pgen.1010828
  60. Genetics. 2023 Jul 13. pii: iyad129. [Epub ahead of print]
    Identification and Characterization of Protein Interactions with the Major Niemann-Pick Type C Disease Protein in Yeast Reveals Pathways of Therapeutic Potential.
    Natalie Hammond, Jamie Snider, Igor Stagljar, Kevin Mitchell, Kirill Lagutin, Matthew Jessulat, Mohan Babu, Paul H Teesdale-Spittle, Jeffrey P Sheridan, Stephen L Sturley, Andrew B Munkacsi.
      Niemann-Pick type C (NP-C) disease is a rare lysosomal storage disease caused by mutations in NPC1 (95% cases) or NPC2 (5% cases). These proteins function together in cholesterol egress from the lysosome, whereby upon mutation, cholesterol and other lipids accumulate causing major pathologies. However, it is not fully understood how cholesterol is transported from NPC1 residing at the lysosomal membrane to the endoplasmic reticulum and plasma membrane. The yeast orthologue of NPC1, Niemann-Pick type C related protein-1 (Ncr1), functions similarly to NPC1; when transfected into a mammalian cell lacking NPC1, Ncr1 rescues the diagnostic hallmarks of cholesterol and sphingolipid accumulation. Here we aimed to identify and characterise protein-protein interactions (PPIs) with the yeast Ncr1 protein. A genome-wide split-ubiquitin membrane yeast two-hybrid (MYTH) protein interaction screen identified 11 ER membrane-localised, full-length proteins interacting with Ncr1 at the lysosomal/vacuolar membrane. These highlight the importance of ER-vacuole membrane interface and include PPIs with the Cyb5/Cbr1 electron transfer system, the ceramide synthase complex and the Sec61/Sbh1 protein translocation complex. These PPIs were not detected in a sterol auxotrophy condition and thus depend on normal sterol metabolism. To provide biological context for the Ncr1-Cyb5 PPI, a yeast strain lacking this PPI (via gene deletions) exhibited altered levels of sterols and sphingolipids including increased levels of glucosylceramide that mimic NP-C disease. Overall, the results herein provide new physical and genetic interaction models to further use the yeast model of NP-C disease to better understand human NP-C disease.
    Keywords:  lipid transport; lysosomal storage disease; neurodegenerative disease; rare disease; sphingolipid; sterol; yeast model
    DOI:  https://doi.org/10.1093/genetics/iyad129
  61. Mol Nutr Food Res. 2023 Jul 12. e2200763
    Dietary Apigenin Relieves Body Weight and Glycolipid Metabolic Disturbance via Pro-Browning of White Adipose Mediated by Autophagy Inhibition.
    Shaofeng Xiong, Shumin Yu, Kun Wang, Xiaowei Xiong, Min Xia, Guohua Zeng, Qiren Huang.
      SCOPE: Apigenin (AP) has many pharmacological activities, including anti-inflammation, hyperlipidemia-lowering, and so on. Previous studies show that AP can reduce lipid accumulation in adipocytes in vitro. However, it remains unclear whether and how AP can promote fat-browning. Therefore, mouse obesity model and preadipocyte induction model in vitro are used to investigate the effects of AP on glycolipid metabolism, browning and autophagy as well as the possible mechanisms.METHODS AND RESULTS: The obese mice are intragastrically administrated with AP (0.1 mg g-1  d-1 ) for 4 weeks; meanwhile, the differentiating preadipocytes are respectively treated with the indicated concentrations of AP for 48 h. Metabolic phenotype, lipid accumulation, and fat-browning are respectively evaluated by morphological, functional, and specific markers analysis. The results show that AP treatment alleviates the body weight, glycolipid metabolic disorder, and insulin resistance in the obese mice , which is contributed to the pro-browning effects of AP in vivo and in vitro. Moreover, the study finds that the pro-browning effect of AP is accomplished through autophagy inhibition mediated by the activation of PI3K-Akt-mTOR pathway.
    CONCLUSIONS: The findings highlight that autophagy inhibition promotes the browning of white adipocytes and suggest that AP would prevent and treat obesity and the associated metabolic disorders.
    Keywords:  adipocyte; apigenin; autophagy; browning; obesity
    DOI:  https://doi.org/10.1002/mnfr.202200763
  62. FEBS J. 2023 Jul 11.
    Lysosome pH-regulated H+ /K+ switching channel involved in maintaining lysosomal homeostasis.
    Yizhen Wang, Wei Li, Qiaochu Wang.
      Lysosomal pH setpoint and H+ homeostasis is key to the lysosome's functions. The Parkinson's disease-risk protein TMEM175, originally identified as lysosomal K+ channel, works as a H+ -activated H+ channel and discharges the lysosomal H+ store when it is hyper-acidified. Yang et al. indicate that TMEM175 is permeable for both K+ and H+ in the same pore and charges the lysosome with H+ under certain conditions. The charge and discharge functions are under regulation of the lysosomal matrix and glycocalyx layer. Their presented work indicates that TMEM175 performs as a multi-functional channel regulating lysosomal pH in response to physiological conditions.
    Keywords:  TMEM175; glycocalyx; lysosome H+ fluxes
    DOI:  https://doi.org/10.1111/febs.16895
  63. Nutrients. 2023 Jun 30. pii: 2973. [Epub ahead of print]15(13):
    Piceatannol Protects PC-12 Cells against Oxidative Damage and Mitochondrial Dysfunction by Inhibiting Autophagy via SIRT3 Pathway.
    Jie Liu, Peishi Mai, Zihui Yang, Zongwei Wang, Wei Yang, Ziyuan Wang.
      Oxidative stress has been identified as a major cause of cellular injury in a variety of neurodegenerative disorders. This study aimed to investigate the cytoprotective effects of piceatannol on hydrogen peroxide (H2O2)-induced pheochromocytoma-12 (PC-12) cell damage and explore the underlying mechanisms. Our findings indicated that piceatannol pre-treatment significantly attenuated H2O2-induced PC-12 cell death. Furthermore, piceatannol effectively improved mitochondrial content and mitochondrial function, including enhancing mitochondrial reactive oxygen species (ROS) elimination capacity and increasing mitochondrial transcription factor (TFAM), peroxisome-proliferator-activated receptor-γ coactivator-1α (PGC-1α) and mitochondria Complex IV expression. Meanwhile, piceatannol treatment inhibited mitochondria-mediated autophagy as demonstrated by restoring mitochondrial membrane potential, reducing autophagosome formation and light chain 3B II/I (LC3B II/I) and autophagy-related protein 5 (ATG5) expression level. The protein expression level of SIRT3 was significantly increased by piceatannol in a concentration-dependent manner. However, the cytoprotective effect of piceatannol was dramatically abolished by sirtuin 3 (SIRT3) inhibitor, 3-(1H-1,2,3-Triazol-4-yl) pyridine (3-TYP), which led to an exacerbated mitochondrial dysfunction and autophagy in PC-12 cells under oxidative stress. In addition, the autophagy activator (rapamycin) abrogated the protective effects of piceatannol on PC-12 cell death. These findings demonstrated that piceatannol could alleviate PC-12 cell oxidative damage and mitochondrial dysfunction by inhibiting autophagy via the SIRT3 pathway.
    Keywords:  SIRT3; autophagy; mitochondrial function; oxidative damage; piceatannol
    DOI:  https://doi.org/10.3390/nu15132973
  64. Aquat Toxicol. 2023 Jul 10. pii: S0166-445X(23)00236-9. [Epub ahead of print] 106633
    Bioimaging tools reveal copper processing in fish cells by mitophagy.
    Yiteng Xia, Wen-Xiong Wang.
      As an essential trace metal, copper (Cu) regulation, distribution and detoxification among different cellular organelles remain much unknown. In the current study, bioimaging tool was used in visualizing the locations of Cu among different organelles in fish fin cells isolated from rabbitfish Siganus fuscescens. Exposure concentration of Cu directly affected the Cu bioaccumulation and toxicity. When the exposure dosage of Cu reached 100 µM, it began to damage the cells and affect the cell viability after 10 min of exposure. Remarkably, while various Cu concentrations (50∼150 µM) initially reduced the cell viability, they did not lead to a further loss in viability over extended exposure period. Upon entry to the cells, Cu was mainly targeted to the mitochondria whose number, size and network responded immediately to the incoming Cu. However, Cu toxicity did not increase time-dependently, strongly indicating that these mitochondria damaged by Cu could be removed and its cytotoxicity could be relieved. Bioimaging results showed that lysosomes interacted with the mitochondria, which were subsequently digested within a few minutes. Meanwhile the lysosomal number increased, and the size and pH of lysosomes decreased. These reactions were in line with the observed mitophagy, suggesting that mitochondrial Cu could be detoxified, and the damaged mitochondria were removed by lysosome via mitophagy. By further purifying the cellular organelles, the mitochondrial and lysosomal Cu amounts were quantified and found to be in line with the imaging results. The present study suggested that excessive mitochondrial Cu could be removed via mitophagy to relieve the Cu toxicity.
    Keywords:  Bioimaging; Cu homeostasis; Cu toxicity; Mitophagy
    DOI:  https://doi.org/10.1016/j.aquatox.2023.106633
  65. Biogerontology. 2023 Jul 10.
    Molecular mechanism of caloric restriction mimetics-mediated neuroprotection of age-related neurodegenerative diseases: an emerging therapeutic approach.
    Apoorv Sharma, Abhishek Kumar Singh.
      Aging-induced neurodegenerative diseases (NDs) are significantly increasing health problem worldwide. It has been well documented that oxidative stress is one of the potential causes of aging and age-related NDs. There are no drugs for the treatment of NDs, therefore there is an immediate necessity for the development of strategies/treatments either to prevent or cure age-related NDs. Caloric restriction (CR) and intermittent fasting have been considered as effective strategies in increasing the healthspan and lifespan, but it is difficult to adhere to these routines strictly, which has led to the development of calorie restriction mimetics (CRMs). CRMs are natural compounds that provide similar molecular and biochemical effects of CR, and activate autophagy process. CRMs have been reported to regulate redox signaling by enhancing the antioxidant defense systems through activation of the Nrf2 pathway, and inhibiting ROS generation through attenuation of mitochondrial dysfunction. Moreover, CRMs also regulate redox-sensitive signaling pathways such as the PI3K/Akt and MAPK pathways to promote neuronal cell survival. Here, we discuss the neuroprotective effects of various CRMs at molecular and cellular levels during aging of the brain. The CRMs are envisaged to become a cornerstone of the pharmaceutical arsenal against aging and age-related pathologies.
    Keywords:  Aging; Autophagy; Caloric restriction mimetics (CRMs); Neurodegenerative disorders; Neuroprotection; Redox signaling
    DOI:  https://doi.org/10.1007/s10522-023-10045-y
  66. Am J Transl Res. 2023 ;15(6): 4380-4389
    Increasing autophagy ameliorates all-trans-retinal-activated NLRP3 inflammasomes in human THP-1 macrophages.
    Qingqing Xia, Jie Li, Lingmin Zhang, Yingying Zhou, Zaixing Yang, Jing Xie.
      OBJECTIVE: Severe inflammation, mediated by innate immune sensors, can be observed in the retina and is considered to play an important role in the pathogenesis of retinal degeneration caused by all-trans-retinal (atRAL). However, the underlying mechanism thereof remains elusive. This study investigated the effects of atRAL on the macrophage cell line THP-1 and determined the underlying signaling pathway through pharmacological and genetical manipulation.METHODS: The cytotoxicity of atRAL in THP-1 macrophage cells was assessed using the cell counting kit-8 (CCK-8) assay, and mature IL-1β was detected by enzyme-linked immunosorbent assay (ELISA). We measured levels of NLRP3 and cleaved caspase-1 by western blotting to evaluate the activation of NLRP3 inflammasomes. Oxidative stress was validated by measuring mitochondria-associated reactive oxygen species (ROS) with MitoSOXTM Red staining. Autophagy was assessed with the LC3BII turnover assay and tandem mCherry-eGFP-LC3B fluorescence microscopy.
    RESULTS: The maturation and release of IL-1β were regulated by the activation of the NLRP3 inflammasome. Mitochondria-associated ROS were involved in the regulation of NLRP3 inflammasome activation and caspase-1 cleavage. In addition, atRAL functionally activated autophagy in THP-1 cells, and atRAL-induced NLRP3 inflammasome activation was suppressed by autophagy.
    CONCLUSIONS: atRAL activates both the NLRP3 inflammasome and autophagy in THP-1 cells, and the increasing level of autophagy leads to the inhibition of excessive NLRP3 inflammasome activation. These findings shed new light on the pathogenesis of age-related retinal degeneration.
    Keywords:  All-trans-retinal; NLRP3 inflammasome; age-related macular degeneration; autophagy; reactive oxygen species
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