bims-auttor Biomed News
on Autophagy and mTOR
Issue of 2023–05–14
67 papers selected by
Viktor Korolchuk, Newcastle University
  1. Autophagy and mitophagy: physiological implications in kidney inflammation and diseases.
  2. Inhibition of mTORC2 improves brain injury in epileptic rats by promoting chaperone-mediated autophagy.
  3. Vps13 is required for efficient autophagy in Saccharomyces cerevisiae.
  4. Impact of interorganelle coordination between the conventional early secretory pathway and autophagy in cellular homeostasis and stress response.
  5. The roles of autophagy and mitophagy in corneal pathology: current knowledge and future perspectives.
  6. ATG16L1 is equipped with two distinct WIPI2-binding sites to drive autophagy.
  7. Methods to study primary cilia and autophagy in the brain.
  8. Autophagy-dependent expression of osteopontin and its downstream Stat3 signaling contributes to lymphatic malformation progression to lymphangiosarcoma.
  9. Circadian clock protein BMAL1 broadly influences autophagy and endolysosomal function in astrocytes.
  10. TIM23 facilitates PINK1 activation by safeguarding against OMA1-mediated degradation in damaged mitochondria.
  11. Systems biology of autophagy in leishmanial infection and its diverse role in precision medicine.
  12. FBXL4 suppresses mitophagy by restricting the accumulation of NIX and BNIP3 mitophagy receptors.
  13. Reduced mitophagy is an early feature of NAFLD and liver-specific PARKIN knockout hastens the onset of steatosis, inflammation and fibrosis.
  14. The role of CK2 in the regulation of mitochondrial autophagy induced by rotenone.
  15. Osteocytes autophagy mediated by mTORC2 activation controls osteoblasts differentiation and osteoclasts activities under mechanical loading.
  16. Effect of rapamycin on lysosomal accumulation in a CRISPR/Cas9-based cellular model of VPS13A deficiency.
  17. Targeting macrophage autophagy for inflammation resolution and tissue repair in inflammatory bowel disease.
  18. SARS-CoV-2 Nsp8 induces mitophagy by damaging mitochondria.
  19. mTOR pathway: Insights into an established pathway for brain mosaicism in epilepsy.
  20. Hepatic mTORC2 compensates for loss of adipose mTORC2 in mediating energy storage and glucose homeostasis.
  21. Secretory autophagy-promoted cargo exocytosis requires active RAB37.
  22. Inflammatory, mitochondrial, and senescence-related markers: Underlying biological pathways of muscle aging and new therapeutic targets.
  23. TRPV1 inhibition overcomes cisplatin resistance by blocking autophagy-mediated hyperactivation of EGFR signaling pathway.
  24. Combined effects of functional overload and denervation on skeletal muscle mass and its regulatory proteins in mice.
  25. Evaluation of anti-atherosclerotic effects of Sitagliptin via modulation of the mTOR pathway in male rabbits.
  26. Viral subversion of selective autophagy is critical for biogenesis of virus replication organelles.
  27. Boosting autophagy in anti-tumor proteasome inhibition-mediated cardiotoxicity.
  28. Cadmium-induced Stress: A Close Look at the Relationship between Autophagy and Apoptosis.
  29. Peroxisome Deficiency in Cochlear Hair Cells Causes Hearing Loss by Deregulating BK Channels.
  30. C. elegans as a model to study mitochondrial biology and disease.
  31. The mTOR Signaling Pathway and mTOR Inhibitors in Cancer: Next-generation Inhibitors and Approaches.
  32. Evaluation of the Effectiveness of Various Autophagy Inhibitors in A549 Cancer Stem Cells.
  33. Characterization of the role of TMEM175 in an in vitro lysosomal H+ fluxes model.
  34. How autophagy, a potential therapeutic target, regulates intestinal inflammation.
  35. The endo-lysosomal system in Parkinson's disease: expanding the horizon.
  36. Silicon dioxide nanoparticles compromise decidualization via autophagy impairment to possibly cause embryo resorption.
  37. ATG5 selectively engages virus-tethered BST2/tetherin in an LC3C-associated pathway.
  38. Role of Dysregulated Autophagy in HIV Tat, Cocaine, and cART Mediated NLRP3 Activation in Microglia.
  39. [Advances in molecular function of p62 protein and its role in diseases].
  40. Lysine deserts prevent adventitious ubiquitylation of ubiquitin-proteasome components.
  41. The polyphenol EGCG directly targets intracellular amyloid-β aggregates and promotes their lysosomal degradation.
  42. Molecular Regulation Mechanism of Microglial Autophagy in the Pathology of Alzheimer's Disease.
  43. mTOR signalling pathway in stem cell bioactivities and angiogenesis potential.
  44. The emerging theme of 3'UTR mRNA isoform regulation in reprogramming of cell metabolism.
  45. Crystalline silica-induced macrophage pyroptosis interacting with mitophagy contributes to pulmonary fibrosis via modulating mitochondria homeostasis.
  46. Autophagy benefits the in vitro and in vivo clearance of Talaromyces marneffei.
  47. Autophagy in hepatic macrophages can be regulator and potential therapeutic target of liver diseases: A review.
  48. Orexin pathway in Parkinson's disease: a review.
  49. Tau filaments are tethered within brain extracellular vesicles in Alzheimer's disease.
  50. An effector of 'Candidatus Liberibacter asiaticus' manipulates autophagy to promote bacterial infection.
  51. Combined inhibition of XIAP and autophagy induces apoptosis and differentiation in acute myeloid leukaemia.
  52. Hydroquinone-induced endoplasmic reticulum stress affects TK6 cell autophagy and apoptosis via ATF6-mTOR.
  53. Single-cell multiomic analysis identifies a HOX-PBX gene network regulating the survival of lymphangioleiomyomatosis cells.
  54. Diphenyl disulfide potentiates the apoptosis of breast cancer cells through Bax proteolytic activation with accompanying autophagy.
  55. Multi-omics data integration reveals the molecular network of dysregulation IQGAP2-mTOR promotes cell proliferation.
  56. Look who's TORking: mTOR-mediated integration of cell status and external signals during limb development and endochondral bone growth.
  57. Outlook of PINK1/Parkin signaling in molecular etiology of Parkinson's disease, with insights into Pink1 knockout models.
  58. Lysosomal-associated protein transmembrane 5 ameliorates non-alcoholic steatohepatitis by promoting the degradation of CDC42 in mice.
  59. RNF113A targeted by miR-197 promotes proliferation and inhibits autophagy via CXCR4/CXCL12/AKT/ERK/Beclin1 axis in cervical cancer.
  60. Deubiquitinase USP13 regulates glycolytic reprogramming and progression in osteosarcoma by stabilizing METTL3/m6A/ATG5 axis.
  61. Inosine attenuates rotenone-induced Parkinson's disease in rats by alleviating the imbalance between autophagy and apoptosis.
  62. Maintenance of mitochondrial homeostasis for Alzheimer's disease: Strategies and challenges.
  63. Circadian regulation of mTORC1 signaling via Per2 dependent mechanism disrupts folliculogenesis and oocyte maturation in female mice.
  64. SEC22B inhibition attenuates colorectal cancer aggressiveness and autophagic flux under unfavorable environment.
  65. Induction of endoplasmic reticulum stress is associated with the anti-tumor activity of monepantel across cancer types.
  66. Research progress on the mitochondrial mechanism of age-related non-alcoholic fatty liver.
  67. Depletion of WFS1 compromises mitochondrial function in hiPSC-derived neuronal models of Wolfram syndrome.
  1. Am J Physiol Renal Physiol. 2023 May 11.
    Autophagy and mitophagy: physiological implications in kidney inflammation and diseases.
    Divya Bhatia, Mary E Choi.
      Autophagy is a ubiquitous intracellular cytoprotective quality control program that maintains cellular homeostasis by recycling superfluous cytoplasmic components (lipid droplets, protein, or glycogen aggregates) and invading pathogens. Mitophagy is a selective form of autophagy that by recycling damaged mitochondrial material, which can extracellularly act as damage-associated molecular patterns, prevents their release. Autophagy and mitophagy are indispensable for the maintenance of kidney homeostasis and exert crucial functions during both physiological and disease conditions. Impaired autophagy and mitophagy can negatively impact the pathophysiological state and promote its progression. Autophagy helps in maintaining structural integrity of the kidney. Mitophagy-mediated mitochondrial quality control is explicitly critical for regulating cellular homeostasis in the kidney. Both autophagy and mitophagy attenuate the inflammatory responses in the kidney. Accumulating body of evidence highlights that persistent kidney injury-induced oxidative stress can contribute to dysregulated autophagic and mitophagic responses, and cell death. Autophagy and mitophagy also communicate with programmed cell death pathways (apoptosis, necroptosis), and play important roles in cell survival by preventing nutrient deprivation and regulating oxidative stress. Autophagy and mitophagy are activated in the kidney after acute injury. However, their aberrant hyperactivation can be deleterious and cause tissue damage. The findings on the functions of autophagy and mitophagy in various models of chronic kidney disease are heterogenous, and cell type and context-specific dependent. In this review, we discuss the roles of autophagy and mitophagy in the kidney in regulating inflammatory responses, and during various pathological manifestations.
    Keywords:  AKI; Autophagy; CKD; Kidney inflammation; Mitophagy
    DOI:  https://doi.org/10.1152/ajprenal.00012.2023
  2. Epilepsy Res. 2023 May 05. pii: S0920-1211(23)00086-4. [Epub ahead of print]193 107161
    Inhibition of mTORC2 improves brain injury in epileptic rats by promoting chaperone-mediated autophagy.
    Yihan Zhao, Wenying Zhao, Ying Han.
      Epilepsy can seriously affect children's cognitive and behavioral development. The mechanistic target of rapamycin(mTOR) pathway plays an important role in neurodevelopment and epilepsy, but the mechanism of mechanistic target of rapamycin complex 2 (mTORC2) in epilepsy is still unclear. Here, we compared the similarities and differences of the mechanisms of action of mechanistic target of rapamycin complex 1 (mTORC1) and mTORC2 complex in the pathogenesis of epilepsy. Our research results show that the levels of apoptosis in cortical and hippocampal neurons were upregulated in epileptic rats (F = 32.15, 30.96; both P < 0.01), and epilepsy caused neuronal damage (F = 8.13, 9.43; both P < 0.01). The mTORC2-Akt pathway was activated in the cortex and hippocampus of epileptic rats. Inhibition of mTORC2 resulted in decreased levels of apoptosis and reduced neuronal damage in the cortex and hippocampus of epileptic rats. In the hippocampus, selective inhibition of mTORC2 increased lysosome-associated membrane protein 2 A (LAMP2A) protein expression compared with the control group, and the difference was statistically significant (F = 3.02, P < 0.05). Finally, we concluded that in the hippocampus, selective inhibition of mTORC2 can improve epileptic brain injury in rats by increasing chaperone-mediated autophagy (CMA) levels.
    Keywords:  Apoptosis; Autophagy; Epilepsy; Signaling pathway; mTOR
    DOI:  https://doi.org/10.1016/j.eplepsyres.2023.107161
  3. Contact (Thousand Oaks). 2022 Jan-Dec;5:5
    Vps13 is required for efficient autophagy in Saccharomyces cerevisiae.
    Yuchen Lei, Xin Wen, Daniel J Klionsky.
      Vps13 is a large, conserved protein that transports lipids between membranes. Its localization at multiple organelle membranes and membrane contact sites suggests its important physiological roles. In addition, the high correlation of mutant VPS13 with certain diseases, especially those involving neurodegeneration, makes this protein of considerable biomedical interest. Taking advantage of the fact that yeasts only have one Vps13 protein, the roles of yeast Vps13 have been well studied. However, whether and how Vps13 functions in macroautophagy/autophagy, a process of degradation of cytoplasmic cargoes, have been elusive questions. In this paper, we investigated the role of Vps13 in both non-selective and selective autophagy and found that this protein participates in non-selective autophagy, reticulophagy and pexophagy, but not mitophagy, and that Vps13 plays a role in the late stage of autophagy.
    Keywords:  Membrane; mitophagy; protein trafficking; stress; vacuole
    DOI:  https://doi.org/10.1177/25152564221136388
  4. Front Cell Dev Biol. 2023 ;11 1069256
    Impact of interorganelle coordination between the conventional early secretory pathway and autophagy in cellular homeostasis and stress response.
    Diego Tapia, Viviana A Cavieres, Patricia V Burgos, Jorge Cancino.
      The conventional early secretory pathway and autophagy are two essential interconnected cellular processes that are crucial for maintaining cellular homeostasis. The conventional secretory pathway is an anabolic cellular process synthesizing and delivering proteins to distinct locations, including different organelles, the plasma membrane, and the extracellular media. On the other hand, autophagy is a catabolic cellular process that engulfs damaged organelles and aberrant cytosolic constituents into the double autophagosome membrane. After fusion with the lysosome and autolysosome formation, this process triggers digestion and recycling. A growing list of evidence indicates that these anabolic and catabolic processes are mutually regulated. While knowledge about the molecular actors involved in the coordination and functional cooperation between these two processes has increased over time, the mechanisms are still poorly understood. This review article summarized and discussed the most relevant evidence about the key molecular players implicated in the interorganelle crosstalk between the early secretory pathway and autophagy under normal and stressful conditions.
    Keywords:  KDEL receptor (KDELR); endoplasmic reticulum (ER); lipid droplets (LD); plasma membrane (PM); protein kinase A (PKA); traffic-induced degradation response for secretion (TIDeRS)
    DOI:  https://doi.org/10.3389/fcell.2023.1069256
  5. Front Med (Lausanne). 2023 ;10 1064938
    The roles of autophagy and mitophagy in corneal pathology: current knowledge and future perspectives.
    Rajalakshmy Ayilam Ramachandran, Jose Marcos Sanches, Danielle M Robertson.
      The cornea is the clear dome that covers the front portion of the globe. The primary functions of the cornea are to promote the refraction of light and to protect the eye from invading pathogens, both of which are essential for the preservation of vision. Homeostasis of each cellular layer of the cornea requires the orchestration of multiple processes, including the ability to respond to stress. One mechanism whereby cells respond to stress is autophagy, or the process of "self-eating." Autophagy functions to clear damaged proteins and organelles. During nutrient deprivation, amino acids released from protein breakdown via autophagy are used as a fuel source. Mitophagy, a selective form of autophagy, functions to clear damaged mitochondria. Thus, autophagy and mitophagy are important intracellular degradative processes that sustain tissue homeostasis. Importantly, the inhibition or excessive activation of these processes result in deleterious effects on the cell. In the eye, impairment or inhibition of these mechanisms have been associated with corneal disease, degenerations, and dystrophies. This review summarizes the current body of knowledge on autophagy and mitophagy at all layers in the cornea in both non-infectious and infectious corneal disease, dystrophies, and degenerations. It further highlights the critical gaps in our understanding of mitochondrial dysfunction, with implications for novel therapeutics in clinical practice.
    Keywords:  autophagy; cornea; endothelium; epithelium; mitochondria; mitophagy; stroma
    DOI:  https://doi.org/10.3389/fmed.2023.1064938
  6. Autophagy. 2023 May 10.
    ATG16L1 is equipped with two distinct WIPI2-binding sites to drive autophagy.
    Xinyu Gong, Lifeng Pan.
      The recruitment of ATG12-ATG5-ATG16L1 complex to phagophore mediated by the specific interaction between ATG16L1 and WIPI2, is pivotal to the formation of autophagosomes during macroautophagy. Recently, we reported that ATG16L1 contains two distinct WIPI2-binding sites, the previously reported WIPI2-binding site (WBS1), and the newly identified site (WBS2). By determining the crystal structures of WIPI2 with ATG16L1 WBS1 and WBS2 respectively, we uncovered that, unlike ATG16L1 WBS1, ATG16L1 WBS2 and its binding mechanism to WIPI2 are conserved from yeast to mammals. Using cell-based functional assays, we further demonstrated that the integrity of two WIPI2-binding sites of ATG16L1 is essential for normal autophagic flux. In summary, our study provided mechanistic insights into the interaction of two key autophagic proteins, ATG16L1 and WIPI2, and revealed a dual-binding-site mode adopted by ATG16L1 to associate with WIPI2.
    Keywords:  ATG16L1; Macroautophagy; WIPI2; autophagosome
    DOI:  https://doi.org/10.1080/15548627.2023.2213038
  7. Methods Cell Biol. 2023 ;pii: S0091-679X(23)00010-9. [Epub ahead of print]176 217-234
    Methods to study primary cilia and autophagy in the brain.
    Laura de Las Heras-García, Irati Zabalegui, Olatz Pampliega.
      Autophagy is an intracellular catabolic pathway that allows proteins, organelles, and pathogens to be recycled. Thus, it is crucial to maintain cell homeostasis, especially important in post-mitotic cells as neurons that cannot dilute cellular damage through mitosis. In the last decade, autophagy has been connected to the primary cilium (PC), a small organelle that acts as a sensory hub and is present in most cell types, including astrocytes and neurons. In this chapter, we briefly describe the state-of-the-art of the interplay between autophagy, PC, and its implications for the brain, in healthy and pathophysiological conditions. Deregulations in autophagy can be monitored by numerous assays, both in vivo and in vitro, and so do changes in PC length/number. Here, we relate a practical and user-friendly description of immunofluorescence methods to study autophagy and PC changes in brain slices, including the tissue preparation, confocal microscopy, image analysis, and deconvolution process.
    Keywords:  Astrocyte; Autophagy; Immunohistochemistry; Neuron; Primary cilium
    DOI:  https://doi.org/10.1016/bs.mcb.2023.01.010
  8. Autophagy. 2023 May 11.
    Autophagy-dependent expression of osteopontin and its downstream Stat3 signaling contributes to lymphatic malformation progression to lymphangiosarcoma.
    Fuchun Yang, Jun-Lin Guan.
      Lymphatic malformation (LM) is a vascular anomaly from lymphatic endothelial cells (ECs), and a fraction of the patients could progress to the deadly malignant lymphangiosarcoma (LAS). Using genetic tools to delete an essential autophagy gene Rb1cc1/FIP200 or its mutation specifically blocking its autophagy function, we demonstrated that autophagy inhibition abrogated LM progression to LAS although not affecting LM formation in our recently developed mouse model of LAS. Analysis of the mouse models in vivo and vascular tumor cells in vitro showed that autophagy inhibition reduced vascular tumor cell proliferation in vitro and tumorigenicity in vivo without affecting mTORC1 signaling as an oncogenic driver directly. Transcriptional profiling of autophagy-deficient tumor cells and further mechanistic studies revealed a role for osteopontin (OPN) and its downstream Jak/Stat3 signaling in mediating regulation of vascular tumor cells by autophagy. Together, these results support potential new prophylactic strategies to targeting autophagy and/or its downstream OPN expression to prevent progression of the benign LM to the malignant and deadly LAS.
    Keywords:  Lymphangiosarcoma; Osteopontin; RB1CC1/FIP200; Stat3; autophagy; endothelial cells; lymphatic malformation
    DOI:  https://doi.org/10.1080/15548627.2023.2213527
  9. Proc Natl Acad Sci U S A. 2023 05 16. 120(20): e2220551120
    Circadian clock protein BMAL1 broadly influences autophagy and endolysosomal function in astrocytes.
    Celia A McKee, Alexander J Polino, Melvin W King, Erik S Musiek.
      An emerging role for the circadian clock in autophagy and lysosome function has opened new avenues for exploration in the field of neurodegeneration. The daily rhythms of circadian clock proteins may coordinate gene expression programs involved not only in daily rhythms but in many cellular processes. In the brain, astrocytes are critical for sensing and responding to extracellular cues to support neurons. The core clock protein BMAL1 serves as the primary positive circadian transcriptional regulator and its depletion in astrocytes not only disrupts circadian function but also leads to a unique cell-autonomous activation phenotype. We report here that astrocyte-specific deletion of Bmal1 influences endolysosome function, autophagy, and protein degradation dynamics. In vitro, Bmal1-deficient astrocytes exhibit increased endocytosis, lysosome-dependent protein cleavage, and accumulation of LAMP1- and RAB7-positive organelles. In vivo, astrocyte-specific Bmal1 knockout (aKO) brains show accumulation of autophagosome-like structures within astrocytes by electron microscopy. Transcriptional analysis of isolated astrocytes from young and aged Bmal1 aKO mice indicates broad dysregulation of pathways involved in lysosome function which occur independently of TFEB activation. Since a clear link has been established between neurodegeneration and endolysosome dysfunction over the course of aging, this work implicates BMAL1 as a key regulator of these crucial astrocyte functions in health and disease.
    Keywords:  Bmal1; astrocyte; autophagy; circadian; lysosome
    DOI:  https://doi.org/10.1073/pnas.2220551120
  10. Cell Rep. 2023 Apr 30. pii: S2211-1247(23)00465-5. [Epub ahead of print] 112454
    TIM23 facilitates PINK1 activation by safeguarding against OMA1-mediated degradation in damaged mitochondria.
    Shiori Akabane, Kiyona Watanabe, Hidetaka Kosako, Shun-Ichi Yamashita, Kohei Nishino, Masahiro Kato, Shiori Sekine, Tomotake Kanki, Noriyuki Matsuda, Toshiya Endo, Toshihiko Oka.
      PINK1 is activated by autophosphorylation and forms a high-molecular-weight complex, thereby initiating the selective removal of damaged mitochondria by autophagy. Other than translocase of the outer mitochondrial membrane complexes, members of PINK1-containing protein complexes remain obscure. By mass spectrometric analysis of PINK1 co-immunoprecipitates, we identify the inner membrane protein TIM23 as a component of the PINK1 complex. TIM23 downregulation decreases PINK1 levels and significantly delays autophosphorylation, indicating that TIM23 promotes PINK1 accumulation in response to depolarization. Moreover, inactivation of the mitochondrial protease OMA1 not only enhances PINK1 accumulation but also represses the reduction in PINK1 levels induced by TIM23 downregulation, suggesting that TIM23 facilitates PINK1 activation by safeguarding against degradation by OMA1. Indeed, deficiencies of pathogenic PINK1 mutants that fail to interact with TIM23 are partially restored by OMA1 inactivation. These findings indicate that TIM23 plays a distinct role in activating mitochondrial autophagy by protecting PINK1.
    Keywords:  CP: Cell biology; OMA1; PINK1; TIM23; mitochondrial quality control
    DOI:  https://doi.org/10.1016/j.celrep.2023.112454
  11. Front Mol Biosci. 2023 ;10 1113249
    Systems biology of autophagy in leishmanial infection and its diverse role in precision medicine.
    Vrushali Guhe, Prajakta Ingale, Anil Tambekar, Shailza Singh.
      Autophagy is a contentious issue in leishmaniasis and is emerging as a promising therapeutic regimen. Published research on the impact of autophagic regulation on Leishmania survival is inconclusive, despite numerous pieces of evidence that Leishmania spp. triggers autophagy in a variety of cell types. The mechanistic approach is poorly understood in the Leishmania parasite as autophagy is significant in both Leishmania and the host. Herein, this review discusses the autophagy proteins that are being investigated as potential therapeutic targets, the connection between autophagy and lipid metabolism, and microRNAs that regulate autophagy and lipid metabolism. It also highlights the use of systems biology to develop novel autophagy-dependent therapeutics for leishmaniasis by utilizing artificial intelligence (AI), machine learning (ML), mathematical modeling, network analysis, and other computational methods. Additionally, we have shown many databases for autophagy and metabolism in Leishmania parasites that suggest potential therapeutic targets for intricate signaling in the autophagy system. In a nutshell, the detailed understanding of the dynamics of autophagy in conjunction with lipids and miRNAs unfolds larger dimensions for future research.
    Keywords:  anti-leishmanial drugs; artificial intelligence; autophagy; computational biology; leishmaniasis; lipid droplets; miRNA; systems biology
    DOI:  https://doi.org/10.3389/fmolb.2023.1113249
  12. EMBO J. 2023 May 10. e112767
    FBXL4 suppresses mitophagy by restricting the accumulation of NIX and BNIP3 mitophagy receptors.
    Giang Thanh Nguyen-Dien, Keri-Lyn Kozul, Yi Cui, Brendan Townsend, Prajakta Gosavi Kulkarni, Soo Siang Ooi, Antonio Marzio, Nissa Carrodus, Steven Zuryn, Michele Pagano, Robert G Parton, Michael Lazarou, S Sean Millard, Robert W Taylor, Brett M Collins, Mathew Jk Jones, Julia K Pagan.
      To maintain both mitochondrial quality and quantity, cells selectively remove damaged or excessive mitochondria through mitophagy, which is a specialised form of autophagy. Mitophagy is induced in response to diverse conditions, including hypoxia, cellular differentiation and mitochondrial damage. However, the mechanisms that govern the removal of specific dysfunctional mitochondria under steady-state conditions to fine-tune mitochondrial content are not well understood. Here, we report that SCFFBXL4 , an SKP1/CUL1/F-box protein ubiquitin ligase complex, localises to the mitochondrial outer membrane in unstressed cells and mediates the constitutive ubiquitylation and degradation of the mitophagy receptors NIX and BNIP3 to suppress basal levels of mitophagy. We demonstrate that the pathogenic variants of FBXL4 that cause encephalopathic mtDNA depletion syndrome (MTDPS13) do not efficiently interact with the core SCF ubiquitin ligase machinery or mediate the degradation of NIX and BNIP3. Thus, we reveal a molecular mechanism whereby FBXL4 actively suppresses mitophagy by preventing NIX and BNIP3 accumulation. We propose that the dysregulation of NIX and BNIP3 turnover causes excessive basal mitophagy in FBXL4-associated mtDNA depletion syndrome.
    Keywords:  BNIP3; FBXL4; NIX/BNIP3L; mitochondria; mitophagy
    DOI:  https://doi.org/10.15252/embj.2022112767
  13. Sci Rep. 2023 May 10. 13(1): 7575
    Reduced mitophagy is an early feature of NAFLD and liver-specific PARKIN knockout hastens the onset of steatosis, inflammation and fibrosis.
    R Undamatla, O G Fagunloye, J Chen, L R Edmunds, A Murali, A Mills, B Xie, M M Pangburn, I Sipula, G Gibson, C St Croix, M J Jurczak.
      Nonalcoholic fatty liver disease (NAFLD) encompasses a spectrum of pathologies that includes steatosis, steatohepatitis (NASH) and fibrosis and is strongly associated with insulin resistance and type 2 diabetes. Changes in mitochondrial function are implicated in the pathogenesis of NAFLD, particularly in the transition from steatosis to NASH. Mitophagy is a mitochondrial quality control mechanism that allows for the selective removal of damaged mitochondria from the cell via the autophagy pathway. While past work demonstrated a negative association between liver fat content and rates of mitophagy, when changes in mitophagy occur during the pathogenesis of NAFLD and whether such changes contribute to the primary endpoints associated with the disease are currently poorly defined. We therefore undertook the studies described here to establish when alterations in mitophagy occur during the pathogenesis of NAFLD, as well as to determine the effects of genetic inhibition of mitophagy via conditional deletion of a key mitophagy regulator, PARKIN, on the development of steatosis, insulin resistance, inflammation and fibrosis. We find that loss of mitophagy occurs early in the pathogenesis of NAFLD and that loss of PARKIN accelerates the onset of key NAFLD disease features. These observations suggest that loss of mitochondrial quality control in response to nutritional stress may contribute to mitochondrial dysfunction and the pathogenesis of NAFLD.
    DOI:  https://doi.org/10.1038/s41598-023-34710-x
  14. Toxicol Lett. 2023 May 06. pii: S0378-4274(23)00178-9. [Epub ahead of print]
    The role of CK2 in the regulation of mitochondrial autophagy induced by rotenone.
    Beom Hee Kim, Hyun Chul Koh.
      CK2 regulates receptor-mediated mitophagy that removes damaged mitochondria. The PINK1/Parkin pathways also involve mitochondrial clearance through mitophagy. However, it is not clear whether CK2 regulates PINK1/Parkin-dependent mitophagy in response to stress. Rotenone treatment showed a decrease of FUNDC1 expression in the mitochondrial fraction of SH-SY5Y and HeLa cells, but an increase of PINK1/Parkin expression only in SH-SY5Y cells. Interestingly, CK2 inhibition increased mitochondrial LC3II expression in rotenone-treated HeLa cells, whereas it decreased in SH-SY5Y cells, indicating that CK2 mediates rotenone-induced mitophagy in dopaminergic neurons. Furthermore, FUNDC1 expression increased in rotenone-treated SH-SY5Y cells by CK2 inhibition, whereas it decreased in HeLa cells. CK2 inhibition also blocked the increase of Drp1, PINK1 and Parkin translocation into mitochondria and decrease of PGAM5 expression in rotenone-treated SH-SY5Y cells. As expected, rotenone treatment in PGAM5-knockdown cells reduced the expression of PINK1 and Parkin and decrease of LC3II expression. Interestingly, we observed that knockdown of CK2α or PGAM5 induced a further increase in caspase-3 expression. These results suggest that PINK1/Parkin-dependent mitophagy was dominant over FUNDC1 receptor-mediated mitophagy. Collectively, our findings suggest that CK2 can positively induce PINK1/Parkin-dependent mitophagy, and that mitophagy regulates cytoprotective effects by CK2 signaling in dopaminergic neurons. DATA AVAILABILITY STATEMENT: All data generated or analyzed during this study are available upon request.
    Keywords:  CK2; FUNDC1; Mitophagy; PGAM5; PINK1/Parkin; Rotenone
    DOI:  https://doi.org/10.1016/j.toxlet.2023.05.002
  15. Arch Biochem Biophys. 2023 May 08. pii: S0003-9861(23)00133-9. [Epub ahead of print] 109634
    Osteocytes autophagy mediated by mTORC2 activation controls osteoblasts differentiation and osteoclasts activities under mechanical loading.
    Li Gao, Gen Liu, Xiangnan Wu, Chuanzi Liu, Yiqiao Wang, Meirui Ma, Yuanyuan Ma, Zhichao Hao.
      Autophagy is an important mechanosensitive response for cellular homeostasis and survival in osteocytes. However, the mechanism and its effect on bone metabolism have not yet clarified. The objective of this study was to evaluate how compressive cyclic force (CCF) induced autophagic response in osteocytes and to determine the effect of mechanically induced-autophagy on bone cells including osteocytes, osteoblasts, and osteoclasts. Autophagic puncta observed in MLO-Y4 cells increased after exposure to CCF. The upregulated levels of the LC3-II isoform and the degradation of p62 further confirmed the increased autophagic flux. Additionally, ATP synthesis and release, osteocalcin (OCN) expression, and cell survival increased in osteocytes as well. The Murine osteoblasts MC3T3-E1 cells and RAW 264.7 macrophage cells were cultured in conditioned medium collected from MLO-Y4 cells subjected to CCF. The concentration of FGF23 increased and the concentrations of SOST and M-CSF and RANKL/OPG ratio decreased significantly in the conditioned medium. Moreover, the promotion of osteogenic differentiation in MC3T3-E1 cells and inhibition of osteoclastogenesis and function in RAW 264.7 cells were significantly attenuated when osteocytes autophagy was inhibited by siAtg7. Our findings suggested that CCF induced protective autophagy in osteocytes and subsequently enhanced osteocytes survival and osteoblasts differentiation and downregulated osteoclasts activities. Further study revealed that CCF induced autophagic response in osteocytes through mechanistic target of rapamycin complex 2 (mTORC2) activation. In conclusion, CCF-induced osteocytes autophagy upon mTORC2 activation promoted osteocytes survival and osteogenic response and decreased osteoclastic function. Thus, osteocytes autophagy will provide a promising target for better understanding of bone physiology and treatment of bone diseases.
    Keywords:  Autophagy; Mechanical loading; Osteocytes; mTORC2
    DOI:  https://doi.org/10.1016/j.abb.2023.109634
  16. J Cell Mol Med. 2023 May 10.
    Effect of rapamycin on lysosomal accumulation in a CRISPR/Cas9-based cellular model of VPS13A deficiency.
    A R Tornero-Écija, M A Navas, S Muñoz-Braceras, O Vincent, R Escalante.
      VPS13A is a lipid transfer protein localized at different membrane contact sites between organelles, and mutations in the corresponding gene produce a rare neurodegenerative disease called chorea-acanthocytosis (ChAc). Previous studies showed that VPS13A depletion in HeLa cells results in an accumulation of endosomal and lysosomal markers, suggesting a defect in lysosomal degradation capacity leading to partial autophagic dysfunction. Our goal was to determine whether compounds that modulate the endo-lysosomal pathway could be beneficial in the treatment of ChAc. To test this hypothesis, we first generated a KO model using CRISPR/Cas9 to study the consequences of the absence of VPS13A in HeLa cells. We found that inactivation of VPS13A impairs cell growth, which precludes the use of isolated clones due to the undesirable selection of edited clones with residual protein expression. Therefore, we optimized the use of pool cells obtained shortly after transfection with CRISPR/Cas9 components. These cells are a mixture of wild-type and edited cells that allow a comparative analysis of phenotypes and avoids the selection of clones with residual level of VPS13A expression after long-term growth. Consistent with previous observations by siRNA inactivation, VPS13A inactivation by CRISPR/Cas9 resulted in accumulation of the endo-lysosomal markers RAB7A and LAMP1. Notably, we observed that rapamycin partially suppressed the difference in lysosome accumulation between VPS13A KO and WT cells, suggesting that modulation of the autophagic and lysosomal pathway could be a therapeutic target in the treatment of ChAc.
    Keywords:  CRISPR/Cas9; VPS13A; autophagy; chorea-acanthocytosis; rapamycin
    DOI:  https://doi.org/10.1111/jcmm.17768
  17. Burns Trauma. 2023 ;11 tkad004
    Targeting macrophage autophagy for inflammation resolution and tissue repair in inflammatory bowel disease.
    Er-Jin Wang, Ming-Yue Wu, Zheng-Yu Ren, Ying Zheng, Richard D Ye, Chris Soon Heng Tan, Yitao Wang, Jia-Hong Lu.
      Inflammatory bowel disease (IBD) is a chronic, non-specific, recurrent inflammatory disease, majorly affecting the gastrointestinal tract. Due to its unclear pathogenesis, the current therapeutic strategy for IBD is focused on symptoms alleviation. Autophagy is a lysosome-mediated catabolic process for maintaining cellular homeostasis. Genome-wide association studies and subsequent functional studies have highlighted the critical role of autophagy in IBD via a number of mechanisms, including modulating macrophage function. Macrophages are the gatekeepers of intestinal immune homeostasis, especially involved in regulating inflammation remission and tissue repair. Interestingly, many autophagic proteins and IBD-related genes have been revealed to regulate macrophage function, suggesting that macrophage autophagy is a potentially important process implicated in IBD regulation. Here, we have summarized current understanding of macrophage autophagy function in pathogen and apoptotic cell clearance, inflammation remission and tissue repair regulation in IBD, and discuss how this knowledge can be used as a strategy for IBD treatment.
    Keywords:  Autophagy; Efferocytosis; Inflammation; Inflammatory bowel diseases; Macrophage; Tissue repair
    DOI:  https://doi.org/10.1093/burnst/tkad004
  18. Virol Sin. 2023 May 06. pii: S1995-820X(23)00051-2. [Epub ahead of print]
    SARS-CoV-2 Nsp8 induces mitophagy by damaging mitochondria.
    Shan Zong, Yan Wu, Weiling Li, Qiang You, Qian Peng, Chenghai Wang, Pin Wan, Tao Bai, Yanling Ma, Binlian Sun, Jialu Qiao.
      Autophagy plays an important role in the interaction between viruses and host cells. SARS-CoV-2 infection can disrupt the autophagy process in target cells. However, the precise molecular mechanism is still unknown. In this study, we discovered that the Nsp8 of SARS-CoV-2 could cause an increasing accumulation of autophagosomes by preventing the fusion of autophagosomes and lysosomes. From further investigation, we found that Nsp8 was present on mitochondria and can damage mitochondria to initiate mitophagy. The results of experiments with immunofluorescence revealed that Nsp8 induced incomplete mitophagy. Moreover, both domains of Nsp8 orchestrated their function during Nsp8-induced mitophagy, in which the N-terminal domain colocalized with mitochondria and the C-terminal domain induced auto/mitophagy. This novel finding expands our understanding of the function of Nsp8 in promoting mitochondrial damage and inducing incomplete mitophagy, which helps us to understand the etiology of COVID-19 as well as open up new pathways for creating SARS-CoV-2 treatment methods.
    Keywords:  Autophagy; Mitochondrial damage; Mitophagy; Nsp8; SARS-CoV-2
    DOI:  https://doi.org/10.1016/j.virs.2023.05.003
  19. Neurobiol Dis. 2023 May 04. pii: S0969-9961(23)00158-4. [Epub ahead of print]182 106144
    mTOR pathway: Insights into an established pathway for brain mosaicism in epilepsy.
    Anna Gerasimenko, Sara Baldassari, Stéphanie Baulac.
      The mechanistic target of rapamycin (mTOR) signaling pathway is an essential regulator of numerous cellular activities such as metabolism, growth, proliferation, and survival. The mTOR cascade recently emerged as a critical player in the pathogenesis of focal epilepsies and cortical malformations. The 'mTORopathies' comprise a spectrum of cortical malformations that range from whole brain (megalencephaly) and hemispheric (hemimegalencephaly) abnormalities to focal abnormalities, such as focal cortical dysplasia type II (FCDII), which manifest with drug-resistant epilepsies. The spectrum of cortical dysplasia results from somatic brain mutations in the mTOR pathway activators AKT3, MTOR, PIK3CA, and RHEB and from germline and somatic mutations in mTOR pathway repressors, DEPDC5, NPRL2, NPRL3, TSC1 and TSC2. The mTORopathies are characterized by excessive mTOR pathway activation, leading to a broad range of structural and functional impairments. Here, we provide a comprehensive literature review of somatic mTOR-activating mutations linked to epilepsy and cortical malformations in 292 patients and discuss the perspectives of targeted therapeutics for personalized medicine.
    Keywords:  Brain mosaicism; Cortical development; Cortical malformation; Epilepsy; FCDII; Hemimegalencephaly; Megalencephaly; Somatic mutations; mTOR signaling
    DOI:  https://doi.org/10.1016/j.nbd.2023.106144
  20. Am J Physiol Endocrinol Metab. 2023 May 11.
    Hepatic mTORC2 compensates for loss of adipose mTORC2 in mediating energy storage and glucose homeostasis.
    Irina C Frei, Diana Weissenberger, Christoph Müller, Michael N Hall, Mitsugu Shimobayashi.
      Mammalian target of rapamycin complex 2 (mTORC2) is a protein kinase complex that plays an important role in energy homeostasis. Loss of adipose mTORC2 reduces lipogenic enzyme expression and de novo lipogenesis in adipose tissue. Adipose-specific mTORC2 knockout mice also display triglyceride accumulation in the liver. However, the mechanism and physiological role of hepatic triglyceride accumulation upon loss of adipose mTORC2 are unknown. Here, we show that loss of adipose mTORC2 increases expression of de novo lipogenic enzymes in the liver, thereby causing accumulation of hepatic triglyceride and hypertriglyceridemia. Simultaneous inhibition of lipogenic enzymes in adipose tissue and liver by ablating mTORC2 in both tissues prevented accumulation of hepatic triglycerides and hypertriglyceridemia. However, loss of adipose and hepatic mTORC2 caused severe insulin resistance and glucose intolerance. Thus, our findings suggest that increased hepatic lipogenesis is a compensatory mechanism to cope with loss of lipogenesis in adipose tissue, and further suggest that mTORC2 in adipose tissue and liver plays a crucial role in maintaining whole-body energy homeostasis.
    Keywords:  adipose tissue; de novo lipogenesis; glucose homeostasis; liver; mTORC2
    DOI:  https://doi.org/10.1152/ajpendo.00338.2022
  21. Autophagy. 2023 May 12. 1-2
    Secretory autophagy-promoted cargo exocytosis requires active RAB37.
    Shan-Ying Wu, Yi-Ching Wang, Roberto Zuchini, Kai-Ying Lan, Hsiao-Sheng Liu, Sheng-Hui Lan.
      RAB37 GTPase regulates cargo exocytosis by cycling between an inactive GDP-bound form and an active GTP-bound form. We reveal that RAB37 simultaneously regulates autophagy activation and tissue inhibitor of metalloproteinase 1 (TIMP1) secretion in lung cancer cells under starvation conditions. TIMP1, an inflammatory cytokine, is a known inhibitory molecule of matrix metalloproteinases matrix metalloproteinase 9 and suppresses the mobility of lung cancer cells both in vitro and in vivo through conventional exocytosis under serum-free conditions. Notably, we disclosed that secretory autophagy participates in TIMP1 secretion in a RAB37- and Sec22b-dependent manner. Sec22b, a SNARE family protein, participates in vesicle and membrane fusion of secretory autophagy. Knockdown of Sec22b decreased TIMP1 secretion and cell motility but did not affect cell proliferation under starvation conditions. We confirmed that starvation-activated RAB37 accompanied by Sec22b is essential for secretory autophagy to further enhance TIMP1 exocytosis. We further use an off-label drug amiodarone to demonstrate that autophagy induction facilitates TIMP1 secretion and suppresses the motility and metastasis of lung cancer cells in a RAB37-dependent manner in the lung-to-lung mouse model. In conclusion, we demonstrated that the RAB37 activation plays a pivotal regulatory role in secretory autophagy for TIMP1 secretion in lung cancer.Abbreviations: ATG: autophagy-related gene; GDP: guanosine diphosphate; GTP: guanosine triphosphate; LC3: microtubule-associated protein 1A/1B-light chain 3; SNARE: soluble N-ethylmaleimide-sensitive-factor attachment protein receptor; TIMP1: tissue inhibitor matrix metalloproteinase 1.
    Keywords:  RAB37; TIMP1; lung cancer; metastasis; secretory autophagy
    DOI:  https://doi.org/10.1080/15548627.2023.2210446
  22. Exp Gerontol. 2023 May 09. pii: S0531-5565(23)00125-0. [Epub ahead of print] 112204
    Inflammatory, mitochondrial, and senescence-related markers: Underlying biological pathways of muscle aging and new therapeutic targets.
    Anna Picca, Biliana Lozanoska-Ochser, Riccardo Calvani, Hélio José Coelho-Júnior, Christiaan Leewenburgh, Emanuele Marzetti.
      The maintenance of functional health is pivotal for achieving independent life in older age. The aged muscle is characterized by ultrastructural changes, including loss of type I and type II myofibers and a greater proportion of cytochrome c oxidase deficient and succinate dehydrogenase positive fibers. Both intrinsic (e.g., altered proteostasis, DNA damage, and mitochondrial dysfunction) and extrinsic factors (e.g., denervation, altered metabolic regulation, declines in satellite cells, and inflammation) contribute to muscle aging. Being a hub for several cellular activities, mitochondria are key to myocyte viability and mitochondrial dysfunction has been implicated in age-associated physical decline. The maintenance of functional organelles via mitochondrial quality control (MQC) processes is, therefore, crucial to skeletal myofiber viability. The autophagy-lysosome pathway has emerged as a critical step of MQC in muscle by disposing organelles and proteins via their tagging for autophagosome incorporation and delivery to the lysosome for clearance. This pathway has been reported to be altered in muscle of physically inactive older people. A relationship between this pathway and muscle tissue composition of the lower extremities as well as physical performance has been identified. Therefore, integrating muscle structure and myocyte quality control measures in the evaluation of muscle health may be a promising strategy for devising interventions fostering muscle health.
    Keywords:  Cytokine; Extracellular matrix; Mitochondrial quality; Physical performance; Sarcopenia; Satellite cells
    DOI:  https://doi.org/10.1016/j.exger.2023.112204
  23. Nat Commun. 2023 May 10. 14(1): 2691
    TRPV1 inhibition overcomes cisplatin resistance by blocking autophagy-mediated hyperactivation of EGFR signaling pathway.
    Se Jin Oh, Ji Yeon Lim, Min Kyu Son, Jun Hyeok Ahn, Kwon-Ho Song, Hyo-Jung Lee, Suyeon Kim, Eun Ho Cho, Joon-Yong Chung, Hanbyoul Cho, Hyosun Kim, Jae-Hoon Kim, Jooyoung Park, Jungmin Choi, Sun Wook Hwang, Tae Woo Kim.
      Cisplatin resistance along with chemotherapy-induced neuropathic pain is an important cause of treatment failure for many cancer types and represents an unmet clinical need. Therefore, future studies should provide evidence regarding the mechanisms of potential targets that can overcome the resistance as well as alleviate pain. Here, we show that the emergence of cisplatin resistance is highly associated with EGFR hyperactivation, and that EGFR hyperactivation is arisen by a transcriptional increase in the pain-generating channel, TRPV1, via NANOG. Furthermore, TRPV1 promotes autophagy-mediated EGF secretion via Ca2+ influx, which activates the EGFR-AKT signaling and, consequentially, the acquisition of cisplatin resistance. Importantly, TRPV1 inhibition renders tumors susceptible to cisplatin. Thus, our findings indicate a link among cisplatin resistance, EGFR hyperactivation, and TRPV1-mediated autophagic secretion, and implicate that TRPV1 could be a crucial drug target that could not only overcome cisplatin resistance but also alleviate pain in NANOG+ cisplatin-resistant cancer.
    DOI:  https://doi.org/10.1038/s41467-023-38318-7
  24. Physiol Rep. 2023 May;11(9): e15689
    Combined effects of functional overload and denervation on skeletal muscle mass and its regulatory proteins in mice.
    Kazuki Uemichi, Takanaga Shirai, Tohru Takemasa.
      Skeletal muscle is a highly pliable tissue and various adaptations such as muscle hypertrophy or atrophy are induced by overloading or disuse, respectively. However, the combined effect of overloading and disuse on the quantitative adaptation of skeletal muscle is unknown. Thus, the aim of this study was to investigate the effects of the combined stimuli of overloading and disuse on mouse skeletal muscle mass and the expression of regulatory factors for muscle protein anabolism or catabolism. Male mice from the Institute Cancer Research were subjected to denervation concomitant with unilateral functional overload or functional overload concomitant with unilateral denervation. Disuse and functional overload were induced by sciatic nerve transection (denervation) and synergist ablation, respectively, and the plantaris muscle was harvested 14 days after the operation. Our results showed that denervation attenuated functional overload-induced muscle hypertrophy and functional overload partially ameliorated the denervation-induced muscle atrophy. P70S6K phosphorylation, an indicator of mechanistic target of rapamycin complex 1 (mTORC1) activation, was not increased by unilateral functional overload in denervated muscles or by unilateral denervation in functional overloaded muscles. Denervation did not affect the increase of LC3-II, a marker of autophagy activation, and ubiquitinated protein expression upon unilateral functional overload. Also, functional overload did not affect ubiquitinated protein expression during unilateral denervation. Thus, our findings suggest that functional overload-induced muscle hypertrophy or denervation-induced muscle atrophy was attenuated by the combined stimuli of overload and denervation.
    Keywords:  denervation; functional overload; skeletal muscle
    DOI:  https://doi.org/10.14814/phy2.15689
  25. J Med Life. 2023 Mar;16(3): 451-457
    Evaluation of anti-atherosclerotic effects of Sitagliptin via modulation of the mTOR pathway in male rabbits.
    Hussam Hamza Sahib, Bassim Mohammad, Najah Rayish Hadi.
      Atherosclerosis is a common and serious vascular disease that underlies many cardiovascular and cerebrovascular illnesses, including heart attack and stroke. Atherosclerosis-related illnesses have increased in prevalence and now pose a substantial burden on individuals and society. Autophagy (AP) is a process in which cytoplasmic components are engulfed by a double-membrane structure, such as defective organelles and aged, damaged, and flawed proteins. Autophagy is essential for maintaining a proper cellular equilibrium and plays a vital homeostatic role in physiological settings by liberating nutrients from macromolecules and removing undesirable cellular components. This study aimed to investigate the effect of Sitagliptin on the progression of atherosclerosis. Twenty-one male New Zealand White rabbits weighing 2-2.5 kg each were split into three groups: normal control, atherogenic control, and Sitagliptin-treated. The following parameters: serum triglycerides (TG), total cholesterol (TC), LDL, and a tissue autophagy marker (p62) using ELISA, aortic mRNA expression of mTORC1 marker using Real-Time Quantitative PCR(RT-qPCR), and histological inspection of the aorta were assessed. The mRNA expression of mTORC1 and the lipid profile of aortic tissue are considerably elevated in atherogenic diet-fed animals. Histopathological analysis confirmed the presence of a substantial atherosclerotic lesion in the animals fed an atherogenic diet. However, compared to an atherogenic control group, Sitagliptin dramatically reduced lipid profile, P62 aortic level, and mRNA expression of mTORC1. Sitagliptin medication slowed the development of atherosclerosis via increasing autophagy through suppression of the mTORC1 signaling pathway.
    Keywords:  Sitagliptin; anti-atherosclerotic effects; modulation of mTOR pathway
    DOI:  https://doi.org/10.25122/jml-2022-0298
  26. Nat Commun. 2023 May 10. 14(1): 2698
    Viral subversion of selective autophagy is critical for biogenesis of virus replication organelles.
    Yun Lan, Sophie Wilhelmina van Leur, Julia Ayano Fernando, Ho Him Wong, Martin Kampmann, Lewis Siu, Jingshu Zhang, Mingyuan Li, John M Nicholls, Sumana Sanyal.
      Infection by many (+)RNA viruses is accompanied by ER-expansion and membrane remodelling to form viral replication organelles, followed by assembly and secretion of viral progenies. We previously identified that virus-triggered lipophagy was critical for flaviviral assembly, and is driven by the lipid droplet associated protein Ancient ubiquitin protein 1 (Aup1). A ubiquitin conjugating protein Ube2g2 that functions as a co-factor for Aup1 was identified as a host dependency factor in our study. Here we characterized its function: Ube2g2-deficient cells displayed a dramatic reduction in virus production, which could be rescued by reconstituting the wild-type but not the catalytically deficient (C89K) mutant of Ube2g2, suggesting that its enzymatic activity is necessary. Ube2g2 deficiency did not affect entry of virus particles but resulted in a profound loss in formation of replication organelles, and production of infectious progenies. This phenomenon resulted from its dual activity in (i) triggering lipophagy in conjunction with Aup1, and (ii) degradation of ER chaperones such as Herpud1, SEL1L, Hrd1, along with Sec62 to restrict ER-phagy upon Xbp1-IRE1 triggered ER expansion. Our results therefore underscore an exquisite fine-tuning of selective autophagy by flaviviruses that drive host membrane reorganization during infection to enable biogenesis of viral replication organelles.
    DOI:  https://doi.org/10.1038/s41467-023-38377-w
  27. Aging (Albany NY). 2023 May 08. 15
    Boosting autophagy in anti-tumor proteasome inhibition-mediated cardiotoxicity.
    Eleni-Dimitra Papanagnou, Sentiljana Gumeni, Ioannis P Trougakos.
      
    Keywords:  autophagy; cardiotoxicity; proteasome dysfunction; proteasome inhibitors; proteotoxicity
    DOI:  https://doi.org/10.18632/aging.204724
  28. Toxicol Sci. 2023 May 11. pii: kfad045. [Epub ahead of print]
    Cadmium-induced Stress: A Close Look at the Relationship between Autophagy and Apoptosis.
    Alex Tuffour, Anthony Adebayiga Kosiba, Frank Addai Peprah, Jie Gu, Yang Zhou, Haifeng Shi.
      Stress is acknowledged as one of the major factors responsible for autophagy induction, a tightly regulated process that acts as a pro-death or pro-survival mechanism within cells. Cadmium (Cd), a toxic heavy metal, induces apoptosis and autophagy in cells after exposure to low concentrations. This is due to Cd's ability to induce oxidative stress in cells and tissues by overproducing reactive oxygen species (ROS). Several proteins have been found to mediate the process of autophagy but aspects of their specific roles and targets remain undefined. Though LC3-II and p62 have traditionally been used as biomarkers that define autophagy, recent findings have revealed some limitations to LC3-II since it can be accumulated in cells in an autophagy-independent manner, whereas p62 remains a good determinant of the process. In addition to LC3-II and p62, recent studies have suggested that a new member of the autophagy protein family, the vacuole membrane protein 1 (VMP1), is essential in driving autophagy and could be an important biomarker for detecting the initiation and progression of autophagy. This review therefore focuses on current trends in autophagy biomarkers, the effect of Cd on the expression of LC3-II, p62, VMP1, and Beclin-1 and their relation and inter-regulatory roles in autophagy and apoptosis, pharmacological importance and the mechanisms involved.
    Keywords:  Apoptosis; Autophagy; Cadmium; biomarkers
    DOI:  https://doi.org/10.1093/toxsci/kfad045
  29. Adv Sci (Weinh). 2023 May 12. e2300402
    Peroxisome Deficiency in Cochlear Hair Cells Causes Hearing Loss by Deregulating BK Channels.
    Xiaolong Fu, Peifeng Wan, Ling Lu, Yingcui Wan, Ziyi Liu, Guodong Hong, Shengda Cao, Xiuli Bi, Jing Zhou, Ruifeng Qiao, Siwei Guo, Yu Xiao, Bingzheng Wang, Miao Chang, Wen Li, Peipei Li, Aizhen Zhang, Jin Sun, Renjie Chai, Jiangang Gao.
      The peroxisome is a ubiquitous organelle in rodent cells and plays important roles in a variety of cell types and tissues. It is previously indicated that peroxisomes are associated with auditory function, and patients with peroxisome biogenesis disorders (PBDs) are found to have hearing dysfunction, but the specific role of peroxisomes in hearing remains unclear. In this study, two peroxisome-deficient mouse models (Atoh1-Pex5-/- and Pax2-Pex5-/- ) are established and it is found that peroxisomes mainly function in the hair cells of cochleae. Furthermore, peroxisome deficiency-mediated negative effects on hearing do not involve mitochondrial dysfunction and oxidative damage. Although the mammalian target of rapamycin complex 1 (mTORC1) signaling is shown to function through peroxisomes, no changes are observed in the mTORC1 signaling in Atoh1-Pex5-/- mice when compared to wild-type (WT) mice. However, the expression of large-conductance, voltage-, and Ca2+ -activated K+ (BK) channels is less in Atoh1-Pex5-/- mice as compared to the WT mice, and the administration of activators of BK channels (NS-1619 and NS-11021) restores the auditory function in knockout mice. These results suggest that peroxisomes play an essential role in cochlear hair cells by regulating BK channels. Hence, BK channels appear as the probable target for treating peroxisome-related hearing diseases such as PBDs.
    Keywords:  BK channels; Pex5; hair cells; peroxisome
    DOI:  https://doi.org/10.1002/advs.202300402
  30. Semin Cell Dev Biol. 2023 May 04. pii: S1084-9521(23)00101-5. [Epub ahead of print]
    C. elegans as a model to study mitochondrial biology and disease.
    Tessa Onraet, Steven Zuryn.
      Mitochondria perform a myriad of essential functions that ensure organismal homeostasis, including maintaining bioenergetic capacity, sensing and signalling the presence of pathogenic threats, and determining cell fate. Their function is highly dependent on mitochondrial quality control and the appropriate regulation of mitochondrial size, shape, and distribution during an entire lifetime, as well as their inheritance across generations. The roundworm Caenorhabditis elegans has emerged as an ideal model organism through which to study mitochondria. The remarkable conservation of mitochondrial biology has allowed C. elegans researchers to investigate complex processes that are challenging to study in higher organisms. In this review, we explore the key recent contributions of C. elegans to mitochondrial biology through the lens of mitochondrial dynamics, organellar removal, and mitochondrial inheritance, as well as their involvement in immune responses, various types of stress, and transgenerational signalling.
    Keywords:  Aging; Biogenesis; Fission; Fusion; Mitochondrial disease; Mitophagy; MtDNA; Neurodegeneration; Proteotoxicity; UPRmt
    DOI:  https://doi.org/10.1016/j.semcdb.2023.04.006
  31. Curr Mol Med. 2023 May 09.
    The mTOR Signaling Pathway and mTOR Inhibitors in Cancer: Next-generation Inhibitors and Approaches.
    Murat Ihlamur, Busra Akgul, Yağmur Zengin, Şenay Vural Korkut, Kübra Kelleci, Emrah Şefik Abamor.
      mTOR is a serine/threonine kinase that plays various roles in cell growth, proliferation, and metabolism. mTOR signaling in cancer becomes irregular. Therefore, drugs targeting mTOR have been developed. Although mTOR inhibitors rapamycin and rapamycin rapalogs (everolimus, rapamycin, temsirolimus, deforolimus, etc.) and new generation mTOR inhibitors (Rapalink, Dual PI3K/mTOR inhibitors, etc.) are used in cancer treatments, mTOR resistance mechanisms may inhibit the efficacy of these drugs. Therefore, new inhibition approaches are developed. Although these new inhibition approaches have not been widely investigated in cancer treatment, the use of nanoparticles has been evaluated as a new treatment option in a few types of cancer. This review outlines the functions of mTOR in the cancer process, its resistance mechanisms, and the efficiency of mTOR inhibitors in cancer treatment. Furthermore, it discusses the next-generation mTOR inhibitors and inhibition strategies created using nanoparticles. Since mTOR resistance mechanisms prevent the effects of mTOR inhibitors used in cancer treatments, new inhibition strategies should be developed. Inhibition approaches are created using nanoparticles, and one of them offers a promising treatment option with evidence supporting its effectiveness.
    Keywords:  cancer; mTOR; mTOR inhibitor; nanoparticles; next-generation inhibitors and approaches; resistance mechanisms
    DOI:  https://doi.org/10.2174/1566524023666230509161645
  32. Acta Naturae. 2023 Jan-Mar;15(1):15(1): 19-25
    Evaluation of the Effectiveness of Various Autophagy Inhibitors in A549 Cancer Stem Cells.
    K V Aleksandrova, I I Suvorova.
      Numerous studies have already established that autophagy plays a central role in the survival of all cells, including malignant ones. Autophagy is a central cog in the general mechanism that provides the intracellular proteostasis determining cellular physiological and phenotypic characteristics. The accumulated data show that autophagy largely contributes to cancer cell stemness. Thus, autophagy modulation is considered one of the promising pharmacological targets in therapy aimed at cancer stem cell elimination. However, autophagy is a multi-stage intracellular process that involves numerous protein participants. In addition, the process can be activated simultaneously by various signaling modules. Therefore, it is no small feat to select an effective pharmacological drug against autophagy. What's more, the search for potential chemotherapeutic agents that could eliminate cancer stem cells through pharmacological inhibition of autophagy is still under way. In the present work, we selected a panel of autophagy inhibitors (Autophinib, SBI-0206965, Siramesine, MRT68921, and IITZ-01), some of whom have been recently identified as effective autophagy inhibitors in cancer cells. Using A549 cancer cells, which express the core stem factors Oct4 and Sox2, we evaluated the effect of these drugs on the survival and preservation of the original properties of cancer stem cells. Among the agents selected, only Autophinib demonstrated a significant toxic effect on cancer stem cells. The obtained results demonstrate that autophagy inhibition by Autophinib downregulates the expression of the Sox2 protein in A549 cells, and that this downregulation correlates with a pronounced induction of apoptosis. Moreover, Autophinib-treated A549 cells are unable to form spheroids, which indicates a reduction in stemness. Thus, among the drugs studied, only Autophinib can be considered a potential agent against cancer stem cells.
    Keywords:  Autophinib; Oct4; Sox2; autophagy; cancer stem cells; tumor cells
    DOI:  https://doi.org/10.32607/actanaturae.11891
  33. FEBS J. 2023 May 11.
    Characterization of the role of TMEM175 in an in vitro lysosomal H+ fluxes model.
    Chuanyan Yang, Fuyun Tian, Mei Hu, Chunlan Kang, Meixuan Ping, Yiyao Liu, Meiqin Hu, Haoxing Xu, Ye Yu, Zhaobing Gao, Ping Li.
      Lysosome acidification is a dynamic equilibrium of H+ influx and efflux across the membrane, which is crucial for cell physiology. The vacuolar H+ ATPase (V-ATPase) is responsible for the H+ influx or refilling of lysosomes. TMEM175 was identified as a novel H+ permeable channel on lysosomal membranes, and it plays a critical role in lysosome acidification. However, how TMEM175 participates in lysosomal acidification remains unknown. Here, we present evidence that TMEM175 regulates lysosomal H+ influx and efflux in enlarged lysosomes isolated from COS1 treated with vacuolin-1. By utilizing the whole-endolysosome patch-clamp recording technique, a series of integrated lysosomal H+ influx and efflux signals in a ten-of-second time scale under the physiological pH gradient (luminal pH 4.60, and cytosolic pH 7.20) was recorded from this in vitro system. Lysosomal H+ fluxes constitute both the lysosomal H+ refilling and releasing, and they are asymmetrical processes with distinct featured kinetics for each of the H+ fluxes. Lysosomal H+ fluxes are entirely abolished when TMEM175 losses of function in the F39V mutant and is blocked by the antagonist (2-GBI). Meanwhile, lysosomal H+ fluxes are modulated by the pH-buffering capacity of the lumen and the lysosomal glycosylated membrane proteins, lysosome-associated membrane protein 1 (LAMP1). We propose that the TMEM175-mediated lysosomal H+ fluxes model would provide novel thoughts for studying the pathology of Parkinson`s disease and lysosome storage disorders.
    Keywords:  H+ leak; TMEM175; glycocalyx; lysosome acidification; proton channel
    DOI:  https://doi.org/10.1111/febs.16814
  34. Front Immunol. 2023 ;14 1087677
    How autophagy, a potential therapeutic target, regulates intestinal inflammation.
    Shuang-Lan Chen, Chun-Meng Li, Wei Li, Qing-Song Liu, Shuang-Yuan Hu, Mao-Yuan Zhao, Dong-Sen Hu, Yan-Wei Hao, Jin-Hao Zeng, Yi Zhang.
      Inflammatory bowel disease (IBD) is a group of disorders that cause chronic inflammation in the intestines, with the primary types including ulcerative colitis and Crohn's disease. The link between autophagy, a catabolic mechanism in which cells clear protein aggregates and damaged organelles, and intestinal health has been widely studied. Experimental animal studies and human clinical studies have revealed that autophagy is pivotal for intestinal homeostasis maintenance, gut ecology regulation and other aspects. However, few articles have summarized and discussed the pathways by which autophagy improves or exacerbates IBD. Here, we review how autophagy alleviates IBD through the specific genes (e.g., ATG16L1, IRGM, NOD2 and LRRK2), crosstalk of multiple phenotypes with autophagy (e.g., Interaction of autophagy with endoplasmic reticulum stress, intestinal antimicrobial defense and apoptosis) and autophagy-associated signaling pathways. Moreover, we briefly discuss the role of autophagy in colorectal cancer and current status of autophagy-based drug research for IBD. It should be emphasized that autophagy has cell-specific and environment-specific effects on the gut. One of the problems of IBD research is to understand how autophagy plays a role in intestinal tract under specific environmental factors. A better understanding of the mechanism of autophagy in the occurrence and progression of IBD will provide references for the development of therapeutic drugs and disease management for IBD in the future.
    Keywords:  autophagy; autophagy-associated gene; endoplasmic reticulum stress; inflammatory bowel disease; intestinal microflora; signaling pathway
    DOI:  https://doi.org/10.3389/fimmu.2023.1087677
  35. J Mol Biol. 2023 May 04. pii: S0022-2836(23)00218-8. [Epub ahead of print] 168140
    The endo-lysosomal system in Parkinson's disease: expanding the horizon.
    Amitha Muraleedharan, Benoît Vanderperre.
      Parkinson's disease (PD) is the second most common neurodegenerative disorder after Alzheimer's disease, and its prevalence is increasing with age. A wealth of genetic evidence indicates that the endo-lysosomal system is a major pathway driving PD pathogenesis with a growing number of genes encoding endo-lysosomal proteins identified as risk factors for PD, making it a promising target for therapeutic intervention. However, detailed knowledge and understanding of the molecular mechanisms linking these genes to the disease are available for only a handful of them (e.g. LRRK2, GBA1, VPS35). Taking on the challenge of studying poorly characterized genes and proteins can be daunting, due to the limited availability of tools and knowledge from previous literature. This review aims at providing a valuable source of molecular and cellular insights into the biology of lesser-studied PD-linked endo-lysosomal genes, to help and encourage researchers in filling the knowledge gap around these less popular genetic players. Specific endo-lysosomal pathways discussed range from endocytosis, sorting, and vesicular trafficking to the regulation of membrane lipids of these membrane-bound organelles and the specific enzymatic activities they contain. We also provide perspectives on future challenges that the community needs to tackle and propose approaches to move forward in our understanding of these poorly studied endo-lysosomal genes. This will help harness their potential in designing innovative and efficient treatments to ultimately re-establish neuronal homeostasis in PD but also other diseases involving endo-lysosomal dysfunction.
    Keywords:  Ceramide; Cholesterol; Endosomes; Lysosomes; Trafficking
    DOI:  https://doi.org/10.1016/j.jmb.2023.168140
  36. Toxicol Lett. 2023 May 09. pii: S0378-4274(23)00179-0. [Epub ahead of print]
    Silicon dioxide nanoparticles compromise decidualization via autophagy impairment to possibly cause embryo resorption.
    Ying Bai, Fang-Fang Li, Yi Zhang, Yu-Bin Ding.
      The wide application of silicon dioxide nanoparticles (SiO2NPs) has raised concerns about their harmful effects on reproduction. The purpose of this research was to investigate the toxic effects and the possible mechanisms by which SiO2NPs affect decidualization and pregnancy progression. We found that SiO2NPs could inhibit decidualization, both in mice and in human endometrial stromal cells (HESCs). Embryo resorption was also evident in mice treated with SiO2NPs. When HESCs were treated with SiO2NPs, decidualization was inhibited and there was an increase in intracellular lysosomes and autophagosomes as well as the blockage of autophagic flux. Interestingly, a reduction of autophagosome accumulation via 3-methyladenine (3MA) significantly restored the decidualization of HESCs. In summary, our results indicate that SiO2NPs can affect embryo survival by impairing decidualization through a dysfunctional autophagic process.
    Keywords:  autophagy; decidualization; lysosome; silicon dioxide nanoparticles
    DOI:  https://doi.org/10.1016/j.toxlet.2023.05.003
  37. Proc Natl Acad Sci U S A. 2023 05 16. 120(20): e2217451120
    ATG5 selectively engages virus-tethered BST2/tetherin in an LC3C-associated pathway.
    Delphine Judith, Margaux Versapuech, Fabienne Bejjani, Marjory Palaric, Pauline Verlhac, Aurelia Kuster, Leslie Lepont, Sarah Gallois-Montbrun, Katy Janvier, Clarisse Berlioz-Torrent.
      Bone marrow stromal antigen 2 (BST2)/tetherin is a restriction factor that reduces HIV-1 dissemination by tethering virus at the cell surface. BST2 also acts as a sensor of HIV-1 budding, establishing a cellular antiviral state. The HIV-1 Vpu protein antagonizes BST2 antiviral functions via multiple mechanisms, including the subversion of an LC3C-associated pathway, a key cell intrinsic antimicrobial mechanism. Here, we describe the first step of this viral-induced LC3C-associated process. This process is initiated at the plasma membrane through the recognition and internalization of virus-tethered BST2 by ATG5, an autophagy protein. ATG5 and BST2 assemble as a complex, independently of the viral protein Vpu and ahead of the recruitment of the ATG protein LC3C. The conjugation of ATG5 with ATG12 is dispensable for this interaction. ATG5 recognizes cysteine-linked homodimerized BST2 and specifically engages phosphorylated BST2 tethering viruses at the plasma membrane, in an LC3C-associated pathway. We also found that this LC3C-associated pathway is used by Vpu to attenuate the inflammatory responses mediated by virion retention. Overall, we highlight that by targeting BST2 tethering viruses, ATG5 acts as a signaling scaffold to trigger an LC3C-associated pathway induced by HIV-1 infection.
    Keywords:  ATG5; BST2/tetherin; HIV-1; LC3-associated pathway; non-canonical autophagy
    DOI:  https://doi.org/10.1073/pnas.2217451120
  38. J Neuroimmune Pharmacol. 2023 May 06.
    Role of Dysregulated Autophagy in HIV Tat, Cocaine, and cART Mediated NLRP3 Activation in Microglia.
    Seema Singh, Annadurai Thangaraj, Ernest T Chivero, Ming-Lei Guo, Palsamy Periyasamy, Shilpa Buch.
      Despite the ability of combination antiretroviral therapy (cART) to suppress viremia, there is persistence low levels of HIV proteins such as Transactivator of transcription (Tat) in the central nervous system (CNS), contributing to glial activation and neuroinflammation. Accumulating evidence also implicates the role of drugs of abuse in exacerbating neurological complications associated with HIV-1. The combined effects of HIV Tat, drugs of abuse, and cART can thus create a toxic milieu in the CNS. The present study investigated the combinatorial effects of HIV-Tat, cocaine, and cART on autophagy and NLRP3 inflammasome activation. We selected a combination of three commonly used cART regimens: tenofovir, emtricitabine, and dolutegravir. Our results demonstrated that exposure of mouse primary microglia (MPMs) to these agents-HIV Tat (25 ng/ml), cocaine (1 μM), and cART (1 μM each) resulted in upregulation of autophagy markers: Beclin1, LC3B-II, and SQSTM1 with impaired lysosomal functioning involving increased lysosomal pH, decreased LAMP2 and cathepsin D, ultimately leading to dysregulated autophagy. Our findings also demonstrated activation of the NLRP3 signaling in microglia exposed to these agents. We further demonstrated that gene silencing of key autophagy protein BECN1 significantly blocked NLRP3-mediated activation of microglia. Silencing of NLRP3, however, failed to block HIV Tat, cocaine, and cART-mediated dysregulation of the autophagy-lysosomal axis; these in vitro phenomena were also validated in vivo using iTat mice administered cocaine and cART. This study thus underscores the cooperative effects of HIV Tat, cocaine, and cART in exacerbating microglial activation involving dysregulated autophagy and activation of the NLRP3 inflammasome signaling.
    Keywords:  Autophagy; Cocaine; HIV Tat; Microglia activation; NLRP3; Neuroinflammation
    DOI:  https://doi.org/10.1007/s11481-023-10063-0
  39. Sheng Wu Gong Cheng Xue Bao. 2023 Apr 25. 39(4): 1374-1389
    [Advances in molecular function of p62 protein and its role in diseases].
    Xinying Sui, Ping Xu, Changzhu Duan, Yanchang Li.
      Sequestosome 1 (SQSTM1/p62) is a selective autophagy adaptor protein that plays an important role in the clearance of proteins to be degraded as well as in the maintenance of cellular proteostasis. p62 protein has multiple functional domains, which interact with several downstream proteins to precisely regulate multiple signaling pathways, thereby linking p62 to oxidative defense systems, inflammatory responses and nutrient sensing. Studies have shown that mutation or abnormal expression of p62 is closely related to the occurrence and development of various diseases, including neurodegenerative diseases, tumors, infectious diseases, genetic diseases and chronic diseases. This review summarizes the structural features and molecular functions of p62. Moreover, we systematically introduce its multiple functions in protein homeostasis and regulation of signaling pathways. Furthermore, the complexity and versatility of p62 in the occurrence and development of diseases are summarized, with the aim to provide a reference for understanding the function of p62 protein and facilitating related disease research.
    Keywords:  SQSTM1/p62; autophagy; disease; proteasome; tumor
    DOI:  https://doi.org/10.13345/j.cjb.220681
  40. Cell Mol Life Sci. 2023 May 09. 80(6): 143
    Lysine deserts prevent adventitious ubiquitylation of ubiquitin-proteasome components.
    Caroline Kampmeyer, Martin Grønbæk-Thygesen, Nicole Oelerich, Michael H Tatham, Matteo Cagiada, Kresten Lindorff-Larsen, Wouter Boomsma, Kay Hofmann, Rasmus Hartmann-Petersen.
      In terms of its relative frequency, lysine is a common amino acid in the human proteome. However, by bioinformatics we find hundreds of proteins that contain long and evolutionarily conserved stretches completely devoid of lysine residues. These so-called lysine deserts show a high prevalence in intrinsically disordered proteins with known or predicted functions within the ubiquitin-proteasome system (UPS), including many E3 ubiquitin-protein ligases and UBL domain proteasome substrate shuttles, such as BAG6, RAD23A, UBQLN1 and UBQLN2. We show that introduction of lysine residues into the deserts leads to a striking increase in ubiquitylation of some of these proteins. In case of BAG6, we show that ubiquitylation is catalyzed by the E3 RNF126, while RAD23A is ubiquitylated by E6AP. Despite the elevated ubiquitylation, mutant RAD23A appears stable, but displays a partial loss of function phenotype in fission yeast. In case of UBQLN1 and BAG6, introducing lysine leads to a reduced abundance due to proteasomal degradation of the proteins. For UBQLN1 we show that arginine residues within the lysine depleted region are critical for its ability to form cytosolic speckles/inclusions. We propose that selective pressure to avoid lysine residues may be a common evolutionary mechanism to prevent unwarranted ubiquitylation and/or perhaps other lysine post-translational modifications. This may be particularly relevant for UPS components as they closely and frequently encounter the ubiquitylation machinery and are thus more susceptible to nonspecific ubiquitylation.
    Keywords:  Degradation; Intrinsically disordered protein; Lysine; PTM; Proteasome; Ubiquitin
    DOI:  https://doi.org/10.1007/s00018-023-04782-z
  41. J Neurochem. 2023 May 11.
    The polyphenol EGCG directly targets intracellular amyloid-β aggregates and promotes their lysosomal degradation.
    Christopher Secker, Angelika Y Motzny, Simona Kostova, Alexander Buntru, Lucas Helmecke, Laura Reus, Robert Steinfort, Lydia Brusendorf, Annett Boeddrich, Nancy Neuendorf, Lisa Diez, Peter Schmieder, Aline Schulz, Constantin Czekelius, Erich E Wanker.
      The accumulation of amyloidogenic protein aggregates in neurons is a pathogenic hallmark of a large number of neurodegenerative diseases including Alzheimer's disease (AD). Small molecules targeting such structures and promoting their degradation may have therapeutic potential for the treatment of AD. Here, we searched for natural chemical compounds that decrease the abundance of stable, proteotoxic β-sheet-rich amyloid-β (Aβ) aggregates in cells. We found that the polyphenol (-)-epigallocatechin gallate (EGCG) functions as a potent chemical aggregate degrader (CAD) in SH-EP cells. We further demonstrate that a novel, fluorescently labeled EGCG derivative (EGC-dihydroxybenzoate (DHB)-Rhodamine) also shows cellular activity. It directly targets intracellular Aβ42 aggregates and competes with EGCG for Aβ42 aggregate binding in vitro. Mechanistic investigations indicated a lysosomal accumulation of Aβ42 aggregates in SH-EP cells and showed that lysosomal cathepsin activity is critical for efficient EGCG-mediated aggregate clearance. In fact, EGCG treatment leads to an increased abundance of active cathepsin B isoforms and increased enzymatic activity in our SH-EP cell model. Our findings suggest that intracellular Aβ42 aggregates are cleared through the endo-lysosomal system. We show that EGCG directly targets intracellular Aβ42 aggregates and facilitates their lysosomal degradation. Small molecules, which bind to protein aggregates and increase their lysosomal degradation could have therapeutic potential for the treatment of amyloid diseases.
    Keywords:  Alzheimer's disease; EGCG; EGCG derivatives; amyloid-β; cathepsin; lysosome
    DOI:  https://doi.org/10.1111/jnc.15842
  42. Aging Dis. 2023 01 07.
    Molecular Regulation Mechanism of Microglial Autophagy in the Pathology of Alzheimer's Disease.
    Pei Ou-Yang, Zhi-Yu Cai, Zhong-Hao Zhang.
      Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the progressive accumulation of abnormal protein aggregates, neuronal loss, synaptic dysfunction, and neuroinflammation. Microglia are resident macrophages of the central nervous system (CNS). Evidence has shown that impaired microglial autophagy exerts considerable detrimental impact on the CNS, thus contributing to AD pathogenesis. This review highlights the association between microglial autophagy and AD pathology, with a focus on the inflammatory response, defective clearance, and propagation of Aβ and Tau, and synaptic dysfunction. Mechanistically, several lines of research support the roles of microglial receptors in autophagy regulation during AD. In light of accumulating evidence, a strategy for inducing microglial autophagy has great potential in AD drug development.
    DOI:  https://doi.org/10.14336/AD.2023.0106
  43. Cell Prolif. 2023 May 08. e13499
    mTOR signalling pathway in stem cell bioactivities and angiogenesis potential.
    Hamid Lotfimehr, Narges Mardi, Samaneh Narimani, Hamid Tayefi Nasrabadi, Mohammad Karimipour, Emel Sokullu, Reza Rahbarghazi.
      The mammalian target of rapamycin (mTOR) is a protein kinase that responds to different stimuli such as stresses, starvation and hypoxic conditions. The modulation of this effector can lead to the alteration of cell dynamic growth, proliferation, basal metabolism and other bioactivities. Considering this fact, the mTOR pathway is believed to regulate the diverse functions in several cell lineages. Due to the pleiotropic effects of the mTOR, we here, hypothesize that this effector can also regulate the bioactivity of stem cells in response to external stimuli pathways under physiological and pathological conditions. As a correlation, we aimed to highlight the close relationship between the mTOR signalling axis and the regenerative potential of stem cells in a different milieu. The relevant publications were included in this study using electronic searches of the PubMed database from inception to February 2023. We noted that the mTOR signalling cascade can affect different stem cell bioactivities, especially angiogenesis under physiological and pathological conditions. Modulation of mTOR signalling pathways is thought of as an effective strategy to modulate the angiogenic properties of stem cells.
    DOI:  https://doi.org/10.1111/cpr.13499
  44. Biochem Soc Trans. 2023 May 12. pii: BST20221128. [Epub ahead of print]
    The emerging theme of 3'UTR mRNA isoform regulation in reprogramming of cell metabolism.
    Qiang Zhang, Bin Tian.
      The 3' untranslated region (3'UTR) of mRNA plays a key role in the post-transcriptional regulation of gene expression. Most eukaryotic protein-coding genes express 3'UTR isoforms owing to alternative cleavage and polyadenylation (APA). The 3'UTR isoform expression profile of a cell changes in cell proliferation, differentiation, and stress conditions. Here, we review the emerging theme of regulation of 3'UTR isoforms in cell metabolic reprogramming, focusing on cell growth and autophagy responses through the mTOR pathway. We discuss regulatory events that converge on the Cleavage Factor I complex, a master regulator of APA in 3'UTRs, and recent understandings of isoform-specific m6A modification and endomembrane association in determining differential metabolic fates of 3'UTR isoforms.
    Keywords:  3′UTR; alternative polyadenylation; autophagy; metabolism
    DOI:  https://doi.org/10.1042/BST20221128
  45. J Hazard Mater. 2023 May 03. pii: S0304-3894(23)00845-2. [Epub ahead of print]454 131562
    Crystalline silica-induced macrophage pyroptosis interacting with mitophagy contributes to pulmonary fibrosis via modulating mitochondria homeostasis.
    Yungeng Wei, Yichuan You, Jiarui Zhang, Jiaqi Ban, Hui Min, Chao Li, Jie Chen.
      Environmental exposure to crystalline silica (CS) can lead to silicosis. Alveolar macrophages (AMs) play a crucial role in the pathogenesis of silicosis. Previously, we demonstrated that enhancing AMs mitophagy exerted protective effects on silicosis with a restrained inflammatory response. However, the exact molecular mechanisms are elusive. Pyroptosis and mitophagy are two different biological processes that determine cell fate. Exploring whether there were interactions or balances between these two processes in AMs would provide new insight into treating silicosis. Here we reported that crystalline silica induced pyroptosis in silicotic lungs and AMs with apparent mitochondria injury. Notably, we identified a reciprocal inhibitory effect between mitophagy and pyroptosis cascades in AMs. By enhancing or diminishing mitophagy, we demonstrated that PINK1-mediated mitophagy helped clear damaged mitochondria to negatively regulate CS-induced pyroptosis. While constraining pyroptosis cascades by NLRP3, Caspase1, and GSDMD inhibitors, respectively, displayed enhanced PINK1-dependent mitophagy with lessened CS-injured mitochondria. These observed effects were echoed in the mice with enhanced mitophagy. Therapeutically, we demonstrated abolishing GSDMD-dependent pyroptosis by disulfiram attenuated CS-induced silicosis. Collectively, our data demonstrated that macrophage pyroptosis interacting with mitophagy contributes to pulmonary fibrosis via modulating mitochondria homeostasis, which may provide potential therapeutic targets.
    Keywords:  Crystalline silica; Macrophages; Mitophagy; Pulmonary fibrosis; Pyroptosis
    DOI:  https://doi.org/10.1016/j.jhazmat.2023.131562
  46. Microb Pathog. 2023 May 05. pii: S0882-4010(23)00179-1. [Epub ahead of print]180 106146
    Autophagy benefits the in vitro and in vivo clearance of Talaromyces marneffei.
    Xiao-Wen Huang, Sha Lu, Wen Pan, Mei-Zhen Zhong, Jin-Wei Chai, Ying-Hui Liu, Kang Zeng, Li-Yan Xi.
      Talaromycosis, namely Talaromyces marneffei infection, is increasing gradually and has a high mortality rate even under antifungal therapy. Although autophagy acts differently on different pathogens, it is a promising therapeutic strategy. However, information on autophagy in macrophages and animals upon infection by T. marneffei is still limited. Therefore, several models were employed here to investigate the role of autophagy in host defense against T. marneffei, including RAW264.7 macrophages as in vitro models, different types of Caenorhabditis elegans and BALB/c mice as in vivo models. We applied the clinical T. marneffei isolate SUMS0152 in this study. T. marneffei-infected macrophages exhibit increased formation of autophagosomes. Further, macrophage autophagy promoted by rapamycin or Earle's balanced salt solution (EBSS) inhibited the viability of intracellular T. marneffei. In vivo, compared with uninfected Caenorhabditis elegans, the wild-type nematodes upregulated the expression of the autophagy-related gene lgg-1 and atg-18, and nematodes carrying GFP reporter were induced to form autophagosomes (GFP::LGG-1) after T. marneffei infection. Furthermore, the knockdown of lgg-1 significantly reduced the survival rate of T. marneffei-infected nematodes. Likewise, the autophagy activator rapamycin reduced the fungal burden and suppressed lung inflammation in a mouse model of infection. In conclusion, autophagy is essential for host defense against T. marneffei in vitro and in vivo. Therefore, autophagy may be an attractive target for developing new therapeutics to treat talaromycosis.
    Keywords:  Autophagy; Caenorhabditis elegans; Macrophages; Talaromyces marneffei
    DOI:  https://doi.org/10.1016/j.micpath.2023.106146
  47. Medicine (Baltimore). 2023 May 12. 102(19): e33698
    Autophagy in hepatic macrophages can be regulator and potential therapeutic target of liver diseases: A review.
    Jun Ge, Hao Li, Jia-Qi Yang, Yuan Yue, Sheng-Yu Lu, Hong-Yun Nie, Tao Zhang, Pei-Ming Sun, Hong-Feng Yan, Hong-Wei Sun, Jian-Wu Yang, Jin-Lian Zhou, Yan Cui.
      Hepatic macrophages are a complex population of cells that play an important role in the normal functioning of the liver and in liver diseases. Autophagy, as a maintainer of cellular homeostasis, is closely connected to many liver diseases. And its roles are not always beneficial, but manifesting as a double-edged sword. The polarization of macrophages and the activation of inflammasomes are mediated by intracellular and extracellular signals, respectively, and are important ways for macrophages to take part in a variety of liver diseases. More attention should be paid to autophagy of hepatic macrophages in liver diseases. In this review, we focus on the regulatory role of hepatic macrophages' autophagy in a variety of liver diseases; especially on the upstream regulator of polarization and inflammasomes activation of the hepatic macrophages. We believe that the autophagy of hepatic macrophages can become a potential therapeutic target for management of liver diseases.
    DOI:  https://doi.org/10.1097/MD.0000000000033698
  48. Mol Biol Rep. 2023 May 08.
    Orexin pathway in Parkinson's disease: a review.
    Mohammed Alrouji, Hayder M Al-Kuraishy, Ali I Al-Gareeb, Dalia Zaafar, Gaber El-Saber Batiha.
      Parkinson's disease (PD) is a progressive neurodegenerative disease (NDD) caused by dopaminergic neuron degeneration in the substantia nigra (SN). Orexin is a neuropeptide that plays a role in the pathogenesis of PD. Orexin has neuroprotective properties in dopaminergic neurons. In PD neuropathology, there is also degeneration of orexinergic neurons in the hypothalamus, in addition to dopaminergic neurons. However, the loss of orexinergic neurons in PD began after the degeneration of dopaminergic neurons. Reduced activity of orexinergic neurons has been linked to developing and progressing motor and non-motor symptoms in PD. In addition, the dysregulation of the orexin pathway is linked to the development of sleep disorders. The hypothalamic orexin pathway regulates various aspects of PD neuropathology at the cellular, subcellular, and molecular levels. Finally, non-motor symptoms, particularly insomnia and disturbed sleep, promote neuroinflammation and the accumulation of neurotoxic proteins as a result of defects in autophagy, endoplasmic reticulum (ER) stress, and the glymphatic system. As a result, this review aimed to highlight the potential role of orexin in PD neuropathology.
    Keywords:  Neurodegenerative disease; Neuropathology; Neuropeptide; Orexin; Parkinson’s disease
    DOI:  https://doi.org/10.1007/s11033-023-08459-5
  49. bioRxiv. 2023 Apr 30. pii: 2023.04.30.537820. [Epub ahead of print]
    Tau filaments are tethered within brain extracellular vesicles in Alzheimer's disease.
    S L Fowler, T S Behr, E Turkes, P Maglio Cauhy, M S Foiani, A Schaler, G Crowley, S Bez, E Ficulle, E Tsefou, D P O'Brien, R Fischer, B Geary, P Gaur, C Miller, P D'Acunzo, E Levy, K E Duff, B Ryskeldi-Falcon.
      The abnormal assembly of tau protein in neurons is the pathological hallmark of multiple neurodegenerative diseases, including Alzheimer's disease (AD). In addition, assembled tau associates with extracellular vesicles (EVs) in the central nervous system of patients with AD, which is linked to its clearance and prion-like propagation between neurons. However, the identities of the assembled tau species and the EVs, as well as how they associate, are not known. Here, we combined quantitative mass spectrometry, cryo-electron tomography and single-particle cryo-electron microscopy to study brain EVs from AD patients. We found filaments of truncated tau enclosed within EVs enriched in endo-lysosomal proteins. We observed multiple filament interactions, including with molecules that tethered filaments to the EV limiting membrane, suggesting selective packaging. Our findings will guide studies into the molecular mechanisms of EV-mediated secretion of assembled tau and inform the targeting of EV-associated tau as potential therapeutic and biomarker strategies for AD.
    DOI:  https://doi.org/10.1101/2023.04.30.537820
  50. J Exp Bot. 2023 May 11. pii: erad176. [Epub ahead of print]
    An effector of 'Candidatus Liberibacter asiaticus' manipulates autophagy to promote bacterial infection.
    Hongwei Shi, Zuhui Yang, Jie Huang, Haodi Wu, Shimin Fu, Weimin Li, Xiuping Zou, Changyong Zhou, Xuefeng Wang.
      Autophagy functions in plant host immunity responses to pathogen infection. The molecular mechanisms and functions used by the citrus Huanglongbing (HLB)-associated intracellular bacterium 'Candidatus Liberibacter asiaticus' (CLas) to manipulate autophagy are unknown. We identified a CLas effector, SDE4405 (CLIBASIA_04405), which contributes to HLB progression. Transgenic SDE4405 in Wanjincheng orange (Citrus sinensis) promotes CLas proliferation and symptom expression via suppressing host immunity response. SDE4405 interacts with ATG8-family proteins (ATG8s) and their interactions activate autophagy in Nicotiana benthamiana. The occurrence of autophagy is also significantly enhanced in SDE4405-transgenic citrus plants. Interrupting NbATG8s-SDE4405 interaction by silencing NbATG8s reduces Pseudomonas syringae pv. tomato strain DC3000ΔhopQ1-1 (Pst DC3000ΔhopQ1-1) proliferation in N. benthamiana, and transient overexpression of CsATG8c and SDE4405 in citrus promotes Xanthomonas citri subsp. citri (Xcc) multiplication, suggesting SDE4405-ATG8s interaction negatively regulates plant defense. These data show the role of the CLas effector protein in manipulating autophagy and provide new insights into the molecular interaction between CLas and citrus.
    Keywords:   Candidatus Liberibacter asiaticus; ATG8; Huanglongbing; autophagy; effector; immunity response
    DOI:  https://doi.org/10.1093/jxb/erad176
  51. J Cell Mol Med. 2023 May 08.
    Combined inhibition of XIAP and autophagy induces apoptosis and differentiation in acute myeloid leukaemia.
    Ziyang Huang, Jifan Zhou, Yinyan Jiang, Yixiang Han, Xiaofang Wang, Fanfan Li, Songfu Jiang, Kang Yu, Shenghui Zhang.
      Perturbations in autophagy, apoptosis and differentiation have greatly affected the progression and therapy of acute myeloid leukaemia (AML). The role of X-linked inhibitor of apoptosis (XIAP)-related autophagy remains unclear in AML therapeutics. Here, we found that XIAP was highly expressed and associated with poor overall survival in patients with AML. Furthermore, pharmacologic inhibition of XIAP using birinapant or XIAP knockdown via siRNA impaired the proliferation and clonogenic capacity by inducing autophagy and apoptosis in AML cells. Intriguingly, birinapant-induced cell death was aggravated in combination with ATG5 siRNA or an autophagy inhibitor spautin-1, suggesting that autophagy may be a pro-survival signalling. Spautin-1 further enhanced the ROS level and myeloid differentiation in THP-1 cells treated with birinapant. The mechanism analysis showed that XIAP interacted with MDM2 and p53, and XIAP inhibition notably downregulated p53, substantially increased the AMPKα1 phosphorylation and downregulated the mTOR phosphorylation. Combined treatment using birinapant and chloroquine significantly retarded AML progression in both a subcutaneous xenograft model injected with HEL cells and an orthotopic xenograft model injected intravenously with C1498 cells. Collectively, our data suggested that XIAP inhibition can induce autophagy, apoptosis and differentiation, and combined inhibition of XIAP and autophagy may be a promising therapeutic strategy for AML.
    Keywords:  XIAP; acute myeloid leukaemia; apoptosis; autophagy; differentiation
    DOI:  https://doi.org/10.1111/jcmm.17765
  52. Environ Toxicol. 2023 May 06.
    Hydroquinone-induced endoplasmic reticulum stress affects TK6 cell autophagy and apoptosis via ATF6-mTOR.
    Boxin Li, Hui Yang, Haipeng Wu, Huanhuan Wang, Zhongming Ye, Yao Wu, Yuting Chen, Huanwen Tang.
      Hydroquinone (HQ), one of the main active metabolites of benzene in vivo, 7is commonly used as a surrogate for benzene in in vitro studies and has been shown to be cytotoxic. The aim of this study was to investigate the role of endoplasmic reticulum stress (ERS) in HQ-induced autophagy and apoptosis in human lymphoblastoid cells (TK6) and how activating transcription factor 6 (ATF-6) is involved. We treated TK6 cells with HQ to establish a cytotoxicity model and found that HQ induced cellular ERS, autophagy and apoptosis by Western blot, flow cytometry and transmission electron microscopy. In addition, inhibition of both reactive oxygen species (ROS) and ERS inhibited cellular autophagy and apoptosis, suggesting that ERS may be induced by ROS, which in turn affects autophagy and apoptosis. Our study also found that HQ could inhibit ATF6 expression and mTOR activation. Knockdown of ATF6 enhanced autophagy and apoptosis levels and further inhibited mTOR activation; activation of ATF6 by AA147 enhanced cellular activity, suggesting that ATF6 may affect cellular autophagy and apoptosis through mTOR. In conclusion, our data suggest that ROS mediated ERS may promote autophagy and apoptosis by inhibiting ATF6-mTOR pathway after HQ treatment of TK6 cells.
    Keywords:  ATF6; ROS; apoptosis; autophagy; endoplasmic reticulum stress; mTOR
    DOI:  https://doi.org/10.1002/tox.23814
  53. Sci Adv. 2023 May 10. 9(19): eadf8549
    Single-cell multiomic analysis identifies a HOX-PBX gene network regulating the survival of lymphangioleiomyomatosis cells.
    Tasnim Olatoke, Andrew Wagner, Aristotelis Astrinidis, Erik Y Zhang, Minzhe Guo, Alan G Zhang, Ushodaya Mattam, Elizabeth J Kopras, Nishant Gupta, Eric P Smith, Magdalena Karbowniczek, Maciej M Markiewski, Kathryn A Wikenheiser-Brokamp, Jeffrey A Whitsett, Francis X McCormack, Yan Xu, Jane J Yu.
      Lymphangioleiomyomatosis (LAM) is a rare, progressive lung disease that predominantly affects women. LAM cells carry TSC1/TSC2 mutations, causing mTORC1 hyperactivation and uncontrolled cell growth. mTORC1 inhibitors stabilize lung function; however, sustained efficacy requires long-term administration, and some patients fail to tolerate or respond to therapy. Although the genetic basis of LAM is known, mechanisms underlying LAM pathogenesis remain elusive. We integrated single-cell RNA sequencing and single-nuclei ATAC-seq of LAM lungs to construct a gene regulatory network controlling the transcriptional program of LAM cells. We identified activation of uterine-specific HOX-PBX transcriptional programs in pulmonary LAMCORE cells as regulators of cell survival depending upon HOXD11-PBX1 dimerization. Accordingly, blockage of HOXD11-PBX1 dimerization by HXR9 suppressed LAM cell survival in vitro and in vivo. PBX1 regulated STAT1/3, increased the expression of antiapoptotic genes, and promoted LAM cell survival in vitro. The HOX-PBX gene network provides promising targets for treatment of LAM/TSC mTORC1-hyperactive cancers.
    DOI:  https://doi.org/10.1126/sciadv.adf8549
  54. Environ Toxicol. 2023 May 10.
    Diphenyl disulfide potentiates the apoptosis of breast cancer cells through Bax proteolytic activation with accompanying autophagy.
    Sheng-Yuan Chen, Chien-Chih Chiu, Chun-Tzu Hung, Wen-Hsiung Pan, Yen-Chun Chen, Yung-Ding Bow, Wan-Ju Li, Sheng-Kai Hsu, I-Ling Lin, Zhi-Hong Wen, Chang-Yi Wu.
      Breast cancer is a leading cause of cancer-related death worldwide, and chemoresistance often leads to poor patient outcomes. In this study, we investigated the anticancer activity of synthetic diphenyl disulfide (DPDS) in breast cancer cell lines. DPDS inhibited cellular proliferation and viability in a dose-dependent manner and reduced colony formation, an index of clonogenicity. Annexin-V and 7-AAD double staining showed that DPDS could induce the apoptosis of breast cancer cells. Western blotting of the expression of Bax p21 and its cleaved form p18 suggested the activation of p18 Bax-induced apoptosis. Furthermore, the increased expression of the autophagy marker LC3B-II indicated autophagic lysosome accumulation induced by DPDS. Our findings suggest that DPDS has potential as a candidate for treating breast cancer, and further modifications and optimizations are warranted.
    Keywords:  apoptosis; autophagy; breast cancer; chemoresistance; diphenyl disulfide
    DOI:  https://doi.org/10.1002/tox.23828
  55. Hum Cell. 2023 May 08.
    Multi-omics data integration reveals the molecular network of dysregulation IQGAP2-mTOR promotes cell proliferation.
    Tao Chen, Xijie Fan, Guibin Li, Yuhuan Meng.
      IQGAP2 as a tumor suppressor gene can influence cell proliferation in multiple tumor cell lines. However, the regulation network of cell proliferation resulting solely from the deficiency of IQGAP2 in cells was still unclear. Here, we integrated transcriptome, proteome, and phosphoproteome analyses to investigate the regulatory network of cell proliferation in IQGAP2 knockdown HaCaT and HEK293 cells. Our findings revealed that the dysregulation of the IQGAP2-mTOR molecular network led to increased cell proliferation. We demonstrated that IQGAP2 knockdown enhanced the phosphorylation levels of AKT and S6K, leading to increased cell proliferation. Additionally, we found that AKT and mTOR inhibitors partially rescued abnormal cell proliferation by reducing hyperphosphorylation. Our data suggest a potential connection between the mTOR signaling pathway and aberrant cell proliferation in IQGAP2 knockdown cells. These findings offer a new therapeutic strategy for patients with IQGAP2 deficiency.
    Keywords:  Cell proliferation; IQGAP2; Multi-omics; Regulation networks; mTOR
    DOI:  https://doi.org/10.1007/s13577-023-00912-8
  56. Front Cell Dev Biol. 2023 ;11 1153473
    Look who's TORking: mTOR-mediated integration of cell status and external signals during limb development and endochondral bone growth.
    Chee Ho H'ng, Ashwini Khaladkar, Alberto Rosello-Diez.
      The balance of cell proliferation and size is key for the control of organ development and repair. Moreover, this balance has to be coordinated within tissues and between tissues to achieve robustness in the organ's pattern and size. The tetrapod limb has been used to study these topics during development and repair, and several conserved pathways have emerged. Among them, mechanistic target of rapamycin (mTOR) signaling, despite being active in several cell types and developmental stages, is one of the least understood in limb development, perhaps because of its multiple potential roles and interactions with other pathways. In the body of this review, we have collated and integrated what is known about the role of mTOR signaling in three aspects of tetrapod limb development: 1) limb outgrowth; 2) chondrocyte differentiation after mesenchymal condensation and 3) endochondral ossification-driven longitudinal bone growth. We conclude that, given its ability to interact with the most common signaling pathways, its presence in multiple cell types, and its ability to influence cell proliferation, size and differentiation, the mTOR pathway is a critical integrator of external stimuli and internal status, coordinating developmental transitions as complex as those taking place during limb development. This suggests that the study of the signaling pathways and transcription factors involved in limb patterning, morphogenesis and growth could benefit from probing the interaction of these pathways with mTOR components.
    Keywords:  appendicular; cartilage; endochondral ossification; limb development; mTOR; skeletal
    DOI:  https://doi.org/10.3389/fcell.2023.1153473
  57. Zool Res. 2023 May 18. pii: 2095-8137(2023)03-0559-18. [Epub ahead of print]44(3): 559-576
    Outlook of PINK1/Parkin signaling in molecular etiology of Parkinson's disease, with insights into Pink1 knockout models.
    Zhangting Wang, See-Wing Chan, Hui Zhao, Kai-Kei Miu, Wai-Yee Chan.
      Parkinson's disease (PD) relates to defective mitochondrial quality control in the dopaminergic motor network. Genetic studies have revealed that PINK1 and Parkin mutations are indicative of a heightened propensity to PD onset, pinpointing mitophagy and inflammation as the culprit pathways involved in neuronal loss in the substantia nigra (SNpc). In a reciprocal manner, LRRK2 functions in the regulation of basal flux and inflammatory responses responsible for PINK1/Parkin-dependent mitophagy activation. Pharmacological intervention in these disease-modifying pathways may facilitate the development of novel PD therapeutics, despite the current lack of an established drug evaluation model. As such, we reviewed the feasibility of employing the versatile global Pink1 knockout (KO) rat model as a self-sufficient, spontaneous PD model for investigating both disease etiology and drug pharmacology. These rats retain clinical features encompassing basal mitophagic flux changes with PD progression. We demonstrate the versatility of this PD rat model based on the incorporation of additional experimental insults to recapitulate the proinflammatory responses observed in PD patients.
    Keywords:  Genetic model; Inflammatory response; Mitophagy; Parkinson’s disease; Pink1 KO rats
    DOI:  https://doi.org/10.24272/j.issn.2095-8137.2022.406
  58. Nat Commun. 2023 May 08. 14(1): 2654
    Lysosomal-associated protein transmembrane 5 ameliorates non-alcoholic steatohepatitis by promoting the degradation of CDC42 in mice.
    Lang Jiang, Jing Zhao, Qin Yang, Mei Li, Hao Liu, Xiaoyue Xiao, Song Tian, Sha Hu, Zhen Liu, Peiwen Yang, Manhua Chen, Ping Ye, Jiahong Xia.
      Non-alcoholic steatohepatitis (NASH) has received great attention due to its high incidence. Here, we show that lysosomal-associated protein transmembrane 5 (LAPTM5) is associated with NASH progression through extensive bioinformatical analysis. The protein level of LAPTM5 bears a negative correlation with NAS score. Moreover, LAPTM5 degradation is mediated through its ubiquitination modification by the E3 ubquitin ligase NEDD4L. Discovered by experiments conducted on male mice, hepatocyte-specific depletion of Laptm5 exacerbates mouse NASH symptoms. In contrast, Laptm5 overexpression in hepatocytes exerts diametrically opposite effects. Mechanistically, LAPTM5 interacts with CDC42 and promotes its degradation through a lysosome-dependent manner under the stimulation of palmitic acid, thus inhibiting activation of the mitogen-activated protein kinase signaling pathway. Finally, adenovirus-mediated hepatic Laptm5 overexpression ameliorates aforementioned symptoms in NASH models.
    DOI:  https://doi.org/10.1038/s41467-023-37908-9
  59. Exp Cell Res. 2023 May 08. pii: S0014-4827(23)00179-9. [Epub ahead of print]428(1): 113632
    RNF113A targeted by miR-197 promotes proliferation and inhibits autophagy via CXCR4/CXCL12/AKT/ERK/Beclin1 axis in cervical cancer.
    Qingwei Zhang, Jiayu Song, Leijia Cao, Mingzhen Sun, Tenghan Xu, Shaozhe Yang, Suhong Li, Huifen Wang, Xiuhong Fu.
      Ring Finger Protein 113 (RNF113A), an ubiquitin E3 ligase, is genetically associated with many biological processes, including proliferation, differentiation, cell death, and neurogenesis. Recently, RNF113A has been found to be an abnormal expression in many diseases, such as X-linked trichothiodystrophy syndrome and esophageal cancer. Here, we explore the potential mechanism of RNF113A in the progression of cervical cancer (CC). In this study, we evaluated the expression level and biological function of RNF113A in CC both in vitro and in vivo by bioinformatic prediction, DIA proteomic analysis, compensation experiment, Co-IP, dual-luciferase reporter assay and nude mouse xenograft to identify the RNF113A-associated autophagy pathways involved with tumorigenesis. Consistent with the prediction from biological information analysis, we found that RNF113A was highly expressed in human CC tissues and cells. In addition, this study illustrated that the high expression of RNF113A dramatically promoted proliferation and suppressed autophagy both in vitro and in vivo. In contrast, low expression of RNF113A enhanced autophagy activities and inhibited tumor growth in CC. We also found that miRNA-197, the level of which (negative correlation with RNF113A) declined in human CC, directly restrained the expression of RNF113A. Mechanistically, proteomic and mechanistic assays uncovered that RNF113A confirmed as the direct downstream target of miR-197, promoted proliferation and restrained autophagy in CC not through direct ubiquitination degradation of autophagy marker Beclin1 but via CXCR4/CXCL12/AKT/ERK/Beclin1 signal transduction axis. In summary, we found a new miR-197/RNF113 A/CXCR4/CXCL12/AKT/ERK/Beclin1 regulation pathway that plays an important part in the survival and progression of CC.
    Keywords:  Autophagy; Cervical cancer; Proliferation; RNF113A; miR-197
    DOI:  https://doi.org/10.1016/j.yexcr.2023.113632
  60. Int J Biol Sci. 2023 ;19(7): 2289-2303
    Deubiquitinase USP13 regulates glycolytic reprogramming and progression in osteosarcoma by stabilizing METTL3/m6A/ATG5 axis.
    Ce Wang, Yichen Meng, Jianquan Zhao, Jun Ma, Yuechao Zhao, Rui Gao, Wei Liu, Xuhui Zhou.
      Reprogramming metabolism is a hallmark of cancer cells for rapid progression. However, the detailed functional role of deubiquitinating enzymes (DUBs) in tumor glycolytic reprogramming is still unknown and requires further investigation. USP13 was found to upregulate in osteosarcoma (OS) specimens and promote OS progression through regulating aerobic glycolysis. Interestingly, the m6A writer protein, METTL3, has been identified as a novel target of USP13. USP13 interacts with, deubiquitinates, and therefore stabilizes METTL3 at K488 by removing K48-linked ubiquitin chains. Since METTL3 is a well-known m6A writer and USP13 stabilizes METTL3, we further found that USP13 increased global m6A abundance in OS cells. The results of RNA sequencing and methylated RNA immunoprecipitation sequencing indicated METTL3 could bind to m6A-modified ATG5 mRNA, which is crucial for autophagosome formation, and inhibit ATG5 mRNA decay on an IGF2BP3 dependent manner, thereby promoting autophagy and the autophagy-associated malignancy of OS. Using a small-molecule inhibitor named Spautin-1 to pharmacologically inhibit USP13 induced METTL3 degradation and exhibited significant therapeutic efficacy both in vitro and in vivo. Collectively, our study results indicate that USP13 promotes glycolysis and tumor progression in OS by stabilizing METTL3, thereby stabilizing ATG5 mRNA and facilitating autophagy in OS. Our findings demonstrate the role of the USP13-METTL3-ATG5 cascade in OS progression and show that USP13 is a crucial DUB for the stabilization of METTL3 and a promising therapeutic target for treating OS.
    Keywords:  ATG5; METTL3; N6-methyladenosine; USP13; glycolytic reprogramming
    DOI:  https://doi.org/10.7150/ijbs.82081
  61. Drug Dev Res. 2023 May 12.
    Inosine attenuates rotenone-induced Parkinson's disease in rats by alleviating the imbalance between autophagy and apoptosis.
    Aya M Abd El-Latif, Mostafa A Rabie, Rabab H Sayed, Mai A Abd El Fattah, Sanaa A Kenawy.
      Growing evidence points to impaired autophagy as one of the major factors implicated in the pathophysiology of Parkinson's disease (PD). Autophagy is a downstream target of adenosine monophosphate-activated protein kinase (AMPK). Inosine has already demonstrated a neuroprotective effect against neuronal loss in neurodegenerative diseases, mainly due its anti-inflammatory and antioxidant properties. We, herein, aimed at investigating the neuroprotective effects of inosine against rotenone-induced PD in rats and to focus on the activation of AMPK-mediated autophagy. Inosine successfully increased p-AMPK/AMPK ratio in PD rats and improved their motor performance and muscular co-ordination (assessed by rotarod, open field, and grip strength tests, as well as by manual gait analysis). Furthermore, inosine was able to mitigate the rotenone-induced histopathological alterations and to restore the tyrosine hydroxylase immunoreactivity in PD rats' substantia nigra. Inosine-induced AMPK activation resulted in an autophagy enhancement, as demonstrated by the increased striatal Unc-S1-like kinase1 and beclin-1 expression, and also by the increment light chain 3II to light chain 3I ratio, along with the decline in striatal mammalian target of rapamycin and p62 protein expressions. The inosine-induced stimulation of AMPK also attenuated neuronal apoptosis and promoted antioxidant activity. Unsurprisingly, these neuroprotective effects were antagonized by a preadministration of dorsomorphin (an AMPK inhibitor). In conclusion, inosine exerted neuroprotective effects against the rotenone-induced neuronal loss via an AMPK activation and through the restoration of the imbalance between autophagy and apoptosis. These findings support potential application of inosine in PD treatment.
    Keywords:  AMPK; Inosine; Parkinson's disease; apoptosis; autophagy; substantia nigra
    DOI:  https://doi.org/10.1002/ddr.22077
  62. Redox Biol. 2023 May 06. pii: S2213-2317(23)00135-0. [Epub ahead of print]63 102734
    Maintenance of mitochondrial homeostasis for Alzheimer's disease: Strategies and challenges.
    Ying Han, Daozhou Liu, Ying Cheng, Qifeng Ji, Miao Liu, Bangle Zhang, Siyuan Zhou.
      Alzheimer's disease (AD) is one of the most common neurodegenerative diseases, and its early onset is closely related to mitochondrial energy metabolism. The brain is only 2% of body weight, but consumes 20% of total energy needs. Mitochondria are responsible for providing energy in cells, and maintaining their homeostasis ensures an adequate supply of energy to the brain. Mitochondrial homeostasis is constituted by mitochondrial quantity and quality control, which is dynamically regulated by mitochondrial energy metabolism, mitochondrial dynamics and mitochondrial quality control. Impaired energy metabolism of brain cells occurs early in AD, and maintaining mitochondrial homeostasis is a promising therapeutic target in the future. We summarized the mechanism of mitochondrial homeostasis in AD, its influence on the pathogenesis of early AD, strategies for maintaining mitochondrial homeostasis, and mitochondrial targeting strategies. This review concludes with the authors' opinions on future research and development for mitochondrial homeostasis of early AD.
    Keywords:  Alzheimer's disease; Mitochondrial dynamics; Mitochondrial quality control; Mitochondrial targeting; Oxidative phosphorylation
    DOI:  https://doi.org/10.1016/j.redox.2023.102734
  63. J Mol Histol. 2023 May 10.
    Circadian regulation of mTORC1 signaling via Per2 dependent mechanism disrupts folliculogenesis and oocyte maturation in female mice.
    Gizem Bora, Tuğçe Önel, Ecem Yıldırım, Aylin Yaba.
      mTOR (mammalian target of Rapamycin) is an important signaling pathway involved in several crucial ovarian functions including folliculogenesis and oocyte maturation. The circadian rhythm regulates multiple physiological processes and PER2 is one of the core circadian rhythm components. mTOR is regulated by the circadian clock and in turn, the rhythmic mTOR activities strengthen the clock function. Our current study aims to investigate a possible interconnection between the circadian clock and the mTORC1 signaling pathway in folliculogenesis and oocyte maturation. Here we demonstrate that the circadian system regulates mTORC1 signaling via Per2 dependent mechanism in the mouse ovary. To investigate the effect of constant light on ovarian and oocyte morphology, animals were housed 12:12 h L:D group in standard lightening conditions and the 12:12 h L:L group in constant light for one week. Food intake and body weight changes were measured. Ovarian morphology, follicle counting, and oocyte aging were evaluated. Afterward, western blot for mTOR, p-mTOR, p70S6K, p-p70S6K, PER2, and Caspase-3 protein levels was performed. The study demonstrated that circadian rhythm disruption caused an alteration in their food intake and decrease in primordial follicle numbers and an increase in the number of atretic follicles. It caused an increase in oxidative stress and a decrease in ZP3 expression in oocytes. Decreased protein levels of mTOR, p-mTOR, p70S6K, and PER2 were shown. The results showed that the circadian clock regulates mTORC1 through PER2 dependent mechanism and that decreased mTORC1 activity can contribute to premature aging of mouse ovary. In conclusion, these results suggest that the circadian clock may control ovarian aging by regulating mTOR signaling pathway through Per2 expression.
    Keywords:  Circadian rhythm; Ovarian aging; PER2; mTORC1
    DOI:  https://doi.org/10.1007/s10735-023-10126-9
  64. Biochem Biophys Res Commun. 2023 Mar 15. pii: S0006-291X(23)00324-8. [Epub ahead of print]665 10-18
    SEC22B inhibition attenuates colorectal cancer aggressiveness and autophagic flux under unfavorable environment.
    Jang-Hyun Choi, So-Yeon Park, Won-Jae Lee, Choong-Jae Lee, Jee-Heun Kim, Tae-Young Jang, So-El Jeon, Youngsoo Jun, Jeong-Seok Nam.
      Autophagy has bidirectional functions in cancer by facilitating cell survival and death in a context-dependent manner. Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) are a large family of proteins essential for numerous biological processes, including autophagy; nevertheless, their potential function in cancer malignancy remains unclear. Here, we explored the gene expression patterns of SNAREs in tissues of patients with colorectal cancer (CRC) and discovered that SEC22B expression, a vesicle SNARE, was higher in tumor tissues than in normal tissues, with a more significant increase in metastatic tissues. Interestingly, SEC22B knockdown dramatically decreased CRC cell survival and growth, especially under stressful conditions, such as hypoxia and serum starvation, and decreased the number of stress-induced autophagic vacuoles. Moreover, SEC22B knockdown successfully attenuated liver metastasis in a CRC cell xenograft mouse model, with histological signs of decreased autophagic flux and proliferation within cancer cells. Together, this study posits that SEC22B plays a crucial role in enhancing the aggressiveness of CRC cells, suggesting that SEC22B might be an attractive therapeutic target for CRC.
    Keywords:  Autophagy; Colorectal cancer; Hypoxia; Metastatic colonization; SEC22B; Starvation
    DOI:  https://doi.org/10.1016/j.bbrc.2023.03.039
  65. Cancer Med. 2023 May 06.
    Induction of endoplasmic reticulum stress is associated with the anti-tumor activity of monepantel across cancer types.
    Tiffany J Harris, Yang Liao, Wei Shi, Marco Evangelista, Bhupinder Pal, Hamsa Puthalakath, Roger Aston, Richard Mollard, John M Mariadason, Erinna F Lee, Walter D Fairlie.
       BACKGROUND: Monepantel is an anti-helminthic drug that also has anti-cancer properties. Despite several studies over the years, the molecular target of monepantel in mammalian cells is still unknown, and its mechanism-of-action is not fully understood, though effects on cell cycle, mTOR signalling and autophagy have been implicated.
    METHODS: Viability assays were performed on >20 solid cancer cell cells, and apoptosis assays were performed on a subset of these, including 3D cultures. Genetic deletion of BAX/BAK and ATG were used to establish roles of apoptosis and autophagy in killing activity. RNA-sequencing was performed on four cell lines after monepantel treatment, and differentially regulated genes were confirmed by Western blotting.
    RESULTS: We showed that monepantel has anti-proliferative activity on a broad range of cancer cell lines. In some, this was associated with induction of apoptosis which was confirmed using a BAX/BAK-deficient cell line. However, proliferation is still inhibited in these cells following monepantel treatment, indicating cell-cycle disruption as the major anti-cancer effect. Previous studies have also indicated autophagic cell death occurs following monepantel treatment. We showed autophagy induction in multiple cell lines; however, deletion of a key autophagy regulator ATG7 had minimal impact on monepantel's anti-proliferative activity, suggesting autophagy is associated with, but not required for its anti-tumour effects. Transcriptomic analysis of four cell lines treated with monepantel revealed downregulation of many genes involved in the cell cycle, and upregulation of genes linked to ATF4-mediated ER stress responses, especially those involved in amino-acid metabolism and protein synthesis.
    CONCLUSIONS: As these outcomes are all associated with mTOR signalling, cell cycle and autophagy, we now provide a likely triggering mechanism for the anti-cancer activity of monepantel.
    Keywords:  ER stress; autophagy; cell cycle; mTOR; monepantel
    DOI:  https://doi.org/10.1002/cam4.6021
  66. World J Gastroenterol. 2023 Apr 07. 29(13): 1982-1993
    Research progress on the mitochondrial mechanism of age-related non-alcoholic fatty liver.
    Dan Wang, Duo-Chun Ji, Chun-Yan Yu, Dan-Ni Wu, Ling Qi.
      Non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease worldwide. Reduced activity and slower metabolism in the elderly affect the balance of lipid metabolism in the liver leading to the accumulation of lipids. This affects the mitochondrial respiratory chain and the efficiency of β-oxidation and induces the overproduction of reactive oxygen species. In addition, the dynamic balance of the mitochondria is disrupted during the ageing process, which inhibits its phagocytic function and further aggravates liver injury, leading to a higher incidence of NAFLD in the elderly population. The present study reviewed the manifestations, role and mechanism of mitochondrial dysfunction in the progression of NAFLD in the elderly. Based on the understanding of mitochondrial dysfunction and abnormal lipid metabolism, this study discusses the treatment strategies and the potential therapeutic targets for NAFLD, including lipid accumulation, antioxidation, mitophagy and liver-protecting drugs. The purpose is to provide new ideas for the development of innovative drugs for the prevention and treatment of NAFLD.
    Keywords:  Autophagy; Lipid metabolism; Mitochondria; Non-alcoholic fatty liver disease; Reactive oxygen species; aging
    DOI:  https://doi.org/10.3748/wjg.v29.i13.1982
  67. Stem Cell Reports. 2023 May 09. pii: S2213-6711(23)00136-4. [Epub ahead of print]18(5): 1090-1106
    Depletion of WFS1 compromises mitochondrial function in hiPSC-derived neuronal models of Wolfram syndrome.
    Malgorzata Zatyka, Tatiana R Rosenstock, Congxin Sun, Adina M Palhegyi, Georgina W Hughes, Samuel Lara-Reyna, Dewi Astuti, Alessandro di Maio, Axel Sciauvaud, Miriam E Korsgen, Vesna Stanulovic, Gamze Kocak, Malgorzata Rak, Sandra Pourtoy-Brasselet, Katherine Winter, Thiago Varga, Margot Jarrige, Hélène Polvèche, Joao Correia, Eva-Maria Frickel, Maarten Hoogenkamp, Douglas G Ward, Laetitia Aubry, Timothy Barrett, Sovan Sarkar.
      Mitochondrial dysfunction involving mitochondria-associated ER membrane (MAM) dysregulation is implicated in the pathogenesis of late-onset neurodegenerative diseases, but understanding is limited for rare early-onset conditions. Loss of the MAM-resident protein WFS1 causes Wolfram syndrome (WS), a rare early-onset neurodegenerative disease that has been linked to mitochondrial abnormalities. Here we demonstrate mitochondrial dysfunction in human induced pluripotent stem cell-derived neuronal cells of WS patients. VDAC1 is identified to interact with WFS1, whereas loss of this interaction in WS cells could compromise mitochondrial function. Restoring WFS1 levels in WS cells reinstates WFS1-VDAC1 interaction, which correlates with an increase in MAMs and mitochondrial network that could positively affect mitochondrial function. Genetic rescue by WFS1 overexpression or pharmacological agents modulating mitochondrial function improves the viability and bioenergetics of WS neurons. Our data implicate a role of WFS1 in regulating mitochondrial functionality and highlight a therapeutic intervention for WS and related rare diseases with mitochondrial defects.
    Keywords:  Cyclosporin A; Human induced pluripotent stem cell-derived neurons; Mitochondria-associated ER membrane; Mitochondrial dysfunction; Mitochondrial membrane potential; MnTBAP; Neurodegeneration; VDAC1; WFS1; Wolfram syndrome
    DOI:  https://doi.org/10.1016/j.stemcr.2023.04.002
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