bims-auttor Biomed News
on Autophagy and mTOR
Issue of 2024–03–31
68 papers selected by
Viktor Korolchuk, Newcastle University
  1. Molecular Mechanism of Autophagosome-Lysosome Fusion in Mammalian Cells.
  2. Glycogen Granules Are Degraded by Non-Selective Autophagy in Nitrogen-Starved Komagataella phaffii.
  3. Stress-induced microautophagy is coordinated with lysosome biogenesis and regulated by PIKfyve.
  4. Polyploidy and mTOR signaling: a possible molecular link.
  5. Regulation of Autophagosome-Lysosome Fusion by Human Viral Infections.
  6. RCHY1 and OPTN are required for melanophagy, selective autophagy of melanosomes.
  7. MCOLN1/TRPML1 in the lysosome: a promising target for autophagy modulation in diverse diseases.
  8. Autophagy-Dependent Secretion: Crosstalk between Autophagy and Exosome Biogenesis.
  9. Hypoxia-associated autophagy flux dysregulation in human cancers.
  10. DNA damage-regulated autophagy modulator 1 prevents glioblastoma cells proliferation by regulating lysosomal function and autophagic flux stability.
  11. Autophagosome biogenesis and organelle homeostasis in plant cells.
  12. Targeting of lysosomal-bound protein mEAK-7 for cancer therapy.
  13. TP53INP2-dependent activation of muscle autophagy ameliorates sarcopenia and promotes healthy aging.
  14. Bitter Taste Receptor T2R14 and Autophagy Flux in Gingival Epithelial Cells.
  15. Lipid droplet accumulation in Wdr45-deficient cells caused by impairment of chaperone-mediated autophagic degradation of Fasn.
  16. RPGR is a guanine nucleotide exchange factor for the small GTPase RAB37 required for retinal function via autophagy regulation.
  17. Homocysteine metabolites inhibit autophagy by upregulating miR-21-5p, miR-155-5p, miR-216-5p, and miR-320c-3p in human vascular endothelial cells.
  18. Autophagy-mediated degradation of integumentary tapetum is critical for embryo pattern formation.
  19. Design and validation of a reporter mouse to study the dynamic regulation of TFEB and TFE3 activity through in vivo imaging techniques.
  20. Cloflucarban Illuminates Specificity and Context-Dependent Activation of the PINK1-Parkin Pathway by Mitochondrial Complex Inhibition.
  21. Negative Regulation of Autophagy during Macrophage Infection by Mycobacterium bovis BCG via Protein Kinase C Activation.
  22. Mitophagy mediated by BNIP3 and NIX protects against ferroptosis by downregulating mitochondrial reactive oxygen species.
  23. Mitophagy modulation for the treatment of cardiovascular diseases.
  24. Impaired autophagic flux in the human brain after traumatic brain injury.
  25. Elucidating miR-146a-3p as a key player in autophagy and lipid metabolism in Leishmania major infection.
  26. Interplay of CD36, autophagy, and lipid metabolism: insights into cancer progression.
  27. Antiproliferative activities through accelerating autophagic flux by basidalin and its analogs in human cancer cells.
  28. Rapamycin alleviates mitochondrial dysfunction in anti-NMDAR encephalitis mice.
  29. The GTPase activating protein Gyp7 regulates Rab7/Ypt7 activity on late endosomes.
  30. Glucosylceramide accumulation in microglia triggers STING-dependent neuroinflammation and neurodegeneration in mice.
  31. L-arginine alleviates heat stress-induced mammary gland injury through modulating CASTOR1-mTORC1 axis mediated mitochondrial homeostasis.
  32. Research Progress on Lipophagy-Mediated Exercise Intervention in Non-Alcoholic Fatty Liver Disease.
  33. A pH-response-based fluorescent probe for detecting the mitophagy process by tracing changes in colocalization coefficients.
  34. The dysregulated autophagy in osteoarthritis: Revisiting molecular profile.
  35. Autophagy maintains endosperm quality during seed storage to preserve germination ability in Arabidopsis.
  36. In Silico Investigation of Parkin-Activating Mutations Using Simulations and Network Modeling.
  37. SNX8 enables lysosome reformation and reverses lysosomal storage disorder.
  38. Induction of Autophagy by Extract from Corydalis heterocarpa for Skin Anti-Aging.
  39. The HEAT repeat protein HPO-27 is a lysosome fission factor.
  40. Loss of TMEM106B exacerbates Tau pathology and neurodegeneration in PS19 mice.
  41. RNA Expression of MMP12 Is Strongly Associated with Inflammatory Bowel Disease and Is Regulated by Metabolic Pathways in RAW 264.7 Macrophages.
  42. The Genetics of Tuberous Sclerosis Complex and Related mTORopathies: Current Understanding and Future Directions.
  43. Loss of function of phosphatidylserine synthase causes muscle atrophy in Drosophila.
  44. APP antisense oligonucleotides reduce Aβ aggregation and rescue endolysosomal dysfunction in Alzheimer's disease.
  45. Deafness-associated tRNAPhe mutation impaired mitochondrial and cellular integrity.
  46. The Mitochondrial Connection: The Nek Kinases' New Functional Axis in Mitochondrial Homeostasis.
  47. RACK1 promotes autophagy via the PERK signaling pathway to protect against traumatic brain injury in rats.
  48. Transfer and fates of damaged mitochondria: role in health and disease.
  49. Involvement of DJ-1 in the pathogenesis of intervertebral disc degeneration via hexokinase 2-mediated mitophagy.
  50. Rapamycin increases leukemia cell sensitivity to chemotherapy by regulating mTORC1 pathway-mediated apoptosis and autophagy.
  51. DMC triggers MDA-MB-231 cells apoptosis via inhibiting protective autophagy and PI3K/AKT/mTOR pathway by enhancing ROS level.
  52. Deletion of Dictyostelium tpc2 gene forms multi-tipped structures, regulates autophagy and cell-type patterning.
  53. The level of protein in the maternal murine diet modulates the facial appearance of the offspring via mTORC1 signaling.
  54. Impaired neuronal macroautophagy in the prelimbic cortex contributes to comorbid anxiety-like behaviors in rats with chronic neuropathic pain.
  55. Autophagy-enhancing ATG16L1 polymorphism is associated with improved clinical outcome and T-cell immunity in chronic HIV-1 infection.
  56. The Development of LAT1 Efflux Agonists as Mechanistic Probes of Cellular Amino Acid Stress.
  57. Recent advances of myotubularin-related (MTMR) protein family in cardiovascular diseases.
  58. The race to uncover fission factors for lysosomal organelles heats up.
  59. Se-methylselenocysteine ameliorates mitochondrial function by targeting both mitophagy and autophagy in the mouse model of Alzheimer's disease.
  60. Rab4A-directed endosome traffic shapes pro-inflammatory mitochondrial metabolism in T cells via mitophagy, CD98 expression, and kynurenine-sensitive mTOR activation.
  61. FOXO3/Rab7-Mediated Lipophagy and Its Role in Zn-Induced Lipid Metabolism in Yellow Catfish (Pelteobagrus fulvidraco).
  62. Trimetazidine Improves Mitochondrial Dysfunction in SOD1G93A Cellular Models of Amyotrophic Lateral Sclerosis through Autophagy Activation.
  63. Unraveling the Impact of Dab1 Gene Silencing on the Expression of Autophagy Markers in Lung Development.
  64. SKA2 regulated hyperactive secretory autophagy drives neuroinflammation-induced neurodegeneration.
  65. DDIT3/CHOP promotes LPS/ATP-induced pyroptosis in osteoblasts via mitophagy inhibition.
  66. Salubrinal promotes phospho-eIF2α-dependent activation of UPR leading to autophagy-mediated attenuation of iron-induced insulin resistance.
  67. Drug Repurposing and Lysosomal Storage Disorders: A Trick to Treat.
  68. Insights on E1-like enzyme ATG7: functional regulation and relationships with aging-related diseases.
  1. Cells. 2024 Mar 13. pii: 500. [Epub ahead of print]13(6):
    Molecular Mechanism of Autophagosome-Lysosome Fusion in Mammalian Cells.
    Po-Yuan Ke.
      In eukaryotes, targeting intracellular components for lysosomal degradation by autophagy represents a catabolic process that evolutionarily regulates cellular homeostasis. The successful completion of autophagy initiates the engulfment of cytoplasmic materials within double-membrane autophagosomes and subsequent delivery to autolysosomes for degradation by acidic proteases. The formation of autolysosomes relies on the precise fusion of autophagosomes with lysosomes. In recent decades, numerous studies have provided insights into the molecular regulation of autophagosome-lysosome fusion. In this review, an overview of the molecules that function in the fusion of autophagosomes with lysosomes is provided. Moreover, the molecular mechanism underlying how these functional molecules regulate autophagosome-lysosome fusion is summarized.
    Keywords:  autolysosome; autophagosome; autophagosome–lysosome fusion; autophagy; lysosome
    DOI:  https://doi.org/10.3390/cells13060500
  2. Cells. 2024 Mar 07. pii: 467. [Epub ahead of print]13(6):
    Glycogen Granules Are Degraded by Non-Selective Autophagy in Nitrogen-Starved Komagataella phaffii.
    Nimna V Wijewantha, Ravinder Kumar, Taras Y Nazarko.
      Autophagy was initially recognized as a bulk degradation process that randomly sequesters and degrades cytoplasmic material in lysosomes (vacuoles in yeast). In recent years, various types of selective autophagy have been discovered. Glycophagy, the selective autophagy of glycogen granules, is one of them. While autophagy of glycogen is an important contributor to Pompe disease, which is characterized by the lysosomal accumulation of glycogen, its selectivity is still a matter of debate. Here, we developed the Komagataella phaffii yeast as a simple model of glycogen autophagy under nitrogen starvation conditions to address the question of its selectivity. For this, we turned the self-glucosylating initiator of glycogen synthesis, Glg1, which is covalently bound to glycogen, into the Glg1-GFP autophagic reporter. Our results revealed that vacuolar delivery of Glg1-GFP and its processing to free GFP were strictly dependent on autophagic machinery and vacuolar proteolysis. Notably, this process was independent of Atg11, the scaffold protein common for many selective autophagy pathways. Importantly, the non-mutated Glg1-GFP (which synthesizes and marks glycogen) and mutated Glg1Y212F-GFP (which does not synthesize glycogen and is degraded by non-selective autophagy as cytosolic Pgk1-GFP) were equally well delivered to the vacuole and had similar levels of released GFP. Therefore, we concluded that glycogen autophagy is a non-selective process in K. phaffii yeast under nitrogen starvation conditions.
    Keywords:  Glg1; Komagataella phaffii; Pichia pastoris; autophagy; glycogen; glycogen granules; glycophagy; non-selective autophagy; selective autophagy; yeast
    DOI:  https://doi.org/10.3390/cells13060467
  3. Mol Biol Cell. 2024 Mar 27. mbcE23080332
    Stress-induced microautophagy is coordinated with lysosome biogenesis and regulated by PIKfyve.
    Alison D Klein, Kayla L Petruzzi, Chan Lee, Michael Overholtzer.
      Lysosome turnover and biogenesis are induced in response to treatment of cells with agents that cause membrane rupture, but whether other stress conditions engage similar homeostatic mechanisms is not well understood. Recently we described a form of selective turnover of lysosomes that is induced by metabolic stress or by treatment of cells with ionophores or lysosomotropic agents, involving the formation of intraluminal vesicles within intact organelles through microautophagy. Selective turnover involves non-canonical autophagy and the lipidation of LC3 onto lysosomal membranes, as well as the autophagy gene-dependent formation of intraluminal vesicles. Here we find a form of microautophagy induction that requires activity of the lipid kinase PIKfyve and is associated with the nuclear translocation of TFEB, a known mediator of lysosome biogenesis. We show that LC3 undergoes turnover during this process, and that PIKfyve is required for the formation of intraluminal vesicles and LC3 turnover, but not for LC3 lipidation onto lysosomal membranes, demonstrating that microautophagy is regulated by PIKfyve downstream of non-canonical autophagy. We further show that TFEB activation requires non-canonical autophagy but not PIKfyve, distinguishing the regulation of biogenesis from microautophagy occurring in response to agents that induce lysosomal stress. [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text].
    DOI:  https://doi.org/10.1091/mbc.E23-08-0332
  4. Cell Commun Signal. 2024 Mar 27. 22(1): 196
    Polyploidy and mTOR signaling: a possible molecular link.
    Debopriya Choudhury, Dhruba Ghosh, Meghna Mondal, Didhiti Singha, Ramesh Pothuraju, Pushkar Malakar.
      Polyploidy is typically described as the condition wherein a cell or organism has more than two complete sets of chromosomes. Occurrence of polyploidy is a naturally occurring phenomenon in the body's development and differentiation processes under normal physiological conditions. However, in pathological conditions, the occurrence of polyploidy is documented in numerous disorders, including cancer, aging and diabetes. Due to the frequent association that the polyploidy has with these pathologies and physiological process, understanding the cause and consequences of polyploidy would be beneficial to develop potential therapeutic applications. Many of the genetic and epigenetic alterations leading to cancer, diabetes and aging are linked to signaling pathways. Nonetheless, the specific signaling pathway associated with the cause and consequences of polyploidy still remains largely unknown. Mammalian/mechanistic target of rapamycin (mTOR) plays a key role in the coordination between eukaryotic cell growth and metabolism, thereby simultaneously respond to various environmental inputs including nutrients and growth factors. Extensive research over the past two decades has established a central role for mTOR in the regulation of many fundamental cellular processes that range from protein synthesis to autophagy. Dysregulated mTOR signaling has been found to be implicated in various disease progressions. Importantly, there is a strong correlation between the hallmarks of polyploidy and dysregulated mTOR signaling. In this review, we explore and discuss the molecular connection between mTOR signaling and polyploidy along with its association with cancer, diabetes and aging. Additionally, we address some unanswered questions and provide recommendations to further advance our understanding of the intricate relationship between mTOR signaling and polyploidy.
    Keywords:  Aging; Cancer; Diabetes; Polyploidy; mTOR signaling; mTORC1; mTORC2
    DOI:  https://doi.org/10.1186/s12964-024-01526-9
  5. Pathogens. 2024 Mar 20. pii: 266. [Epub ahead of print]13(3):
    Regulation of Autophagosome-Lysosome Fusion by Human Viral Infections.
    Po-Yuan Ke.
      Autophagy plays a fundamental role in maintaining cellular homeostasis by eliminating intracellular components via lysosomes. Successful degradation through autophagy relies on the fusion of autophagosomes to lysosomes, which leads to the formation of autolysosomes containing acidic proteases that degrade the sequestered materials. Viral infections can exploit autophagy in infected cells to balance virus-host cell interactions by degrading the invading virus or promoting viral growth. In recent years, cumulative studies have indicated that viral infections may interfere with the fusion of autophagosomes and lysosomes, thus benefiting viral replication and associated pathogenesis. In this review, I provide an overview of the current understanding of the molecular mechanism by which human viral infections deregulate autophagosome-lysosome fusion and summarize the physiological significance in the virus life cycle and host cell damage.
    Keywords:  autophagosome; autophagosome–lysosome fusion; autophagy; lysosome; virus
    DOI:  https://doi.org/10.3390/pathogens13030266
  6. Proc Natl Acad Sci U S A. 2024 Apr 02. 121(14): e2318039121
    RCHY1 and OPTN are required for melanophagy, selective autophagy of melanosomes.
    Ki Won Lee, Ki-Jun Ryu, Minju Kim, Seyeon Lim, Jisu Kim, Jeong Yoon Kim, Cheol Hwangbo, Jiyun Yoo, Yong-Yeon Cho, Kwang Dong Kim.
      Melanosomes are specific organelles dedicated to melanin synthesis and accumulation in melanocytes. Autophagy is suggestively involved in melanosome degradation, although the potential underlying molecular mechanisms remain elusive. In selective autophagy, autophagy receptors and E3-ligases are the key factors conferring cargo selectivity. In B16F10 cells, β-mangostin efficiently induced melanosome degradation without affecting other organelles such as mitochondria, peroxisomes, and the endoplasmic reticulum. Among various autophagy receptors, optineurin (OPTN) contributes TANK-binding kinase 1 (TBK1)-dependently to melanosome degradation and its knockdown inhibited β-mangostin-mediated melanosome degradation. OPTN translocation to melanosomes was dependent on its ubiquitin-binding domain. Moreover, OPTN-mediated TBK1 activation and subsequent TBK1-mediated S187 OPTN phosphorylation were essential for melanosome degradation. β-mangostin increased K63-linked melanosome ubiquitination. Finally, the E3-ligase RCHY1 knockdown inhibited the melanosome ubiquitination required for OPTN- and TBK1-phosphorylation as well as melanosome degradation. This study suggests that melanophagy, melanosome-selective autophagy, contributes to melanosome degradation, and OPTN and RCHY1 are an essential autophagy receptor and a E3-ligase, respectively, conferring cargo selectivity in melanophagy.
    Keywords:  OPTN; RCHY1; melanophagy; melanosome; selective autophagy
    DOI:  https://doi.org/10.1073/pnas.2318039121
  7. Autophagy. 2024 Mar 24. 1-11
    MCOLN1/TRPML1 in the lysosome: a promising target for autophagy modulation in diverse diseases.
    Jiansong Qi, Qingqing Li, Tianli Xin, Qixia Lu, Jinyi Lin, Yang Zhang, Haiting Luo, Feifei Zhang, Yanhong Xing, Wuyang Wang, Derong Cui, Mengmeng Wang.
      MCOLN1/TRPML1 is a nonselective cationic channel specifically localized to the late endosome and lysosome. With its property of mediating the release of several divalent cations such as Ca2+, Zn2+ and Fe2+ from the lysosome to the cytosol, MCOLN1 plays a pivotal role in regulating a variety of cellular events including endocytosis, exocytosis, lysosomal biogenesis, lysosome reformation, and especially in Macroautophagy/autophagy. Autophagy is a highly conserved catabolic process that maintains cytoplasmic integrity by removing superfluous proteins and damaged organelles. Acting as the terminal compartments, lysosomes are crucial for the completion of the autophagy process. This review delves into the emerging role of MCOLN1 in controlling the autophagic process by regulating lysosomal ionic homeostasis, thereby governing the fundamental functions of lysosomes. Furthermore, this review summarizes the physiological relevance as well as molecular mechanisms through which MCOLN1 orchestrates autophagy, consequently influencing mitochondria turnover, cell apoptosis and migration. In addition, we have illustrated the implications of MCOLN1-regulated autophagy in the pathological process of cancer and myocardial ischemia-reperfusion (I/R) injury. In summary, given the involvement of MCOLN1-mediated autophagy in the pathogenesis of cancer and myocardial I/R injury, targeting MCOLN1 May provide clues for developing new therapeutic strategies for the treatment of these diseases. Exploring the regulation of MCOLN1-mediated autophagy in diverse diseases contexts will surely broaden our understanding of this pathway and offer its potential as a promising drug target.Abbreviation: CCCP:carbonyl cyanide3-chlorophenylhydrazone; CQ:chloroquine; HCQ: hydroxychloroquine;I/R: ischemia-reperfusion; MAP1LC3/LC3:microtubule associated protein 1 light chain 3; MCOLN1/TRPML1:mucolipin TRP cation channel 1; MLIV: mucolipidosis type IV; MTORC1:MTOR complex 1; ROS: reactive oxygenspecies; SQSTM1/p62: sequestosome 1.
    Keywords:  Autophagy inhibition; MCOLN1; cardiomyocyte death; mitochondria turnover; tumorigenesis
    DOI:  https://doi.org/10.1080/15548627.2024.2333715
  8. Curr Issues Mol Biol. 2024 Mar 08. 46(3): 2209-2235
    Autophagy-Dependent Secretion: Crosstalk between Autophagy and Exosome Biogenesis.
    Ekaterina Zubkova, Alexander Kalinin, Anastasya Bolotskaya, Irina Beloglazova, Mikhail Menshikov.
      The cellular secretome is pivotal in mediating intercellular communication and coordinating responses to stressors. Exosomes, initially recognized for their role in waste disposal, have now emerged as key intercellular messengers with significant therapeutic and diagnostic potential. Similarly, autophagy has transcended its traditional role as a waste removal mechanism, emerging as a regulator of intracellular communication pathways and a contributor to a unique autophagy-dependent secretome. Secretory authophagy, initiated by various stress stimuli, prompts the selective release of proteins implicated in inflammation, including leaderless proteins that bypass the conventional endoplasmic reticulum-Golgi secretory pathway. This reflects the significant impact of stress-induced autophagy on cellular secretion profiles, including the modulation of exosome release. The convergence of exosome biogenesis and autophagy is exemplified by the formation of amphisomes, vesicles that integrate autophagic and endosomal pathways, indicating their synergistic interplay. Regulatory proteins common to both pathways, particularly mTORC1, emerge as potential therapeutic targets to alter cellular secretion profiles involved in various diseases. This review explores the dynamic interplay between autophagy and exosome formation, highlighting the potential to influence the secretome composition. While the modulation of exosome secretion and cytokine preconditioning is well-established in regenerative medicine, the strategic manipulation of autophagy is still underexplored, presenting a promising but uncharted therapeutic landscape.
    Keywords:  amphisomes; exosomes; secretory authophagy; stress; unconventional protein secretion
    DOI:  https://doi.org/10.3390/cimb46030142
  9. Cancer Lett. 2024 Mar 21. pii: S0304-3835(24)00216-7. [Epub ahead of print] 216823
    Hypoxia-associated autophagy flux dysregulation in human cancers.
    Jiding Fu, Jie Lin, Zili Dai, Baisheng Lin, Jian Zhang.
      A general feature of cancer is hypoxia, determined as low oxygen levels. Low oxygen levels may cause cells to alter in ways that contribute to tumor growth and resistance to treatment. Hypoxia leads to variations in cancer cell metabolism, angiogenesis and metastasis. Furthermore, a hypoxic tumor microenvironment might induce immunosuppression. Moreover, hypoxia has the potential to impact cellular processes, such as autophagy. Autophagy refers to the catabolic process by which damaged organelles and toxic macromolecules are broken down. The abnormal activation of autophagy has been extensively recorded in human tumors and it serves as a regulator of cell growth, spread to other parts of the body, and resistance to treatment. There is a correlation between hypoxia and autophagy in human malignancies. Hypoxia can regulate the activity of AMPK, mTOR, Beclin-1, and ATGs to govern autophagy in human malignancies. Furthermore, HIF-1α, serving as an indicator of low oxygen levels, controls the process of autophagy. Hypoxia-induced autophagy has a crucial role in regulating the growth, spread, and resistance to treatment in human malignancies. Hypoxia-induced regulation of autophagy can impact other mechanisms of cell death, such as apoptosis. Chemoresistance and radioresistance have become significant challenges in recent years. Hypoxia-mediated autophagy plays a crucial role in determining the response to these therapeutic treatments.
    Keywords:  Autophagy; Cancer therapy; Cell death; Drug resistance; Hypoxia-inducible factor-1α
    DOI:  https://doi.org/10.1016/j.canlet.2024.216823
  10. Exp Cell Res. 2024 Mar 25. pii: S0014-4827(24)00107-1. [Epub ahead of print]437(2): 114016
    DNA damage-regulated autophagy modulator 1 prevents glioblastoma cells proliferation by regulating lysosomal function and autophagic flux stability.
    Hongqiang Zhang, Lan Luan, Xinyu Li, Xu Sun, Kang Yang.
      Glioblastoma (GBM) is the most aggressive and life-threatening brain tumor, characterized by its highly malignant and recurrent nature. DNA damage-regulated autophagy modulator 1 (DRAM-1) is a p53 target gene encoding a lysosomal protein that induces macro-autophagy and damage-induced programmed cell death in tumor growth. However, the precise mechanisms underlying how DRAM-1 affects tumor cell proliferation through regulation of lysosomal function and autophagic flux stability remain incompletely understood. We found that DRAM-1 expressions were evidently down-regulated in high-grade glioma and recurrent GBM tissues. The upregulation of DRAM-1 could increase mortality of primary cultured GBM cells. TEM analysis revealed an augmented accumulation of aberrant lysosomes in DRAM-1-overexpressing GBM cells. The assay for lysosomal pH and stability also demonstrated decreasing lysosomal membrane permeabilization (LMP) and impaired lysosomal acidity. Further research revealed the detrimental impact of lysosomal dysfunction, which impaired the autophagic flux stability and ultimately led to GBM cell death. Moreover, downregulation of mTOR phosphorylation was observed in GBM cells following upregulation of DRAM-1. In vivo and in vitro experiments additionally illustrated that the mTOR inhibitor rapamycin increased GBM cell mortality and exhibited an enhanced antitumor effect.
    Keywords:  Autophagy; DRAM-1; Glioblastoma; Lysosomal membrane integrity
    DOI:  https://doi.org/10.1016/j.yexcr.2024.114016
  11. Plant Cell. 2024 Mar 27. pii: koae099. [Epub ahead of print]
    Autophagosome biogenesis and organelle homeostasis in plant cells.
    Xiaohong Zhuang, Baiying Li, Liwen Jiang.
      Autophagy is one of the major highly inducible degradation processes in response to plant developmental and environmental signals. In response to different stimuli, cellular materials, including proteins and organelles, can be sequestered into a double membrane autophagosome structure either selectively or non-selectively. The formation of an autophagosome as well as its delivery into the vacuole involves complex and dynamic membrane processes. The identification and characterization of the conserved autophagy-related (ATG) proteins and their related regulators have greatly advanced our understanding of the molecular mechanism underlying autophagosome biogenesis and function in plant cells. Autophagosome biogenesis is tightly regulated by the coordination of multiple ATG and non-ATG proteins, and selective cargo recruitment. This review updates our current knowledge of autophagosome biogenesis, with special emphasis on the core molecular machinery that drives autophagosome formation, and autophagosome-organelle interactions under abiotic stress conditions.
    Keywords:  Autophagosome biogenesis; abiotic stress; autophagy-related (ATG) proteins; membrane dynamics; organelle homeostasis; selective autophagy
    DOI:  https://doi.org/10.1093/plcell/koae099
  12. Front Oncol. 2024 ;14 1375498
    Targeting of lysosomal-bound protein mEAK-7 for cancer therapy.
    Insoon Chang, Yi-Ling Loo, Jay Patel, Joe Truong Nguyen, Jin Koo Kim, Paul H Krebsbach.
      mEAK-7 (mammalian EAK-7 or MTOR-associated protein, eak-7 homolog), is an evolutionarily conserved lysosomal membrane protein that is highly expressed in several cancer cells. Multiple recent studies have identified mEAK-7 as a positive activator of mTOR (mammalian/mechanistic target of rapamycin) signaling via an alternative mTOR complex, implying that mEAK-7 plays an important role in the promotion of cancer proliferation and migration. In addition, structural analyses investigating interactions between mEAK-7 and V-ATPase, a protein complex responsible for regulating pH homeostasis in cellular compartments, have suggested that mEAK-7 may contribute to V-ATPase-mediated mTORC1 activation. The C-terminal α-helix of mEAK-7 binds to the D and B subunits of the V-ATPase, creating a pincer-like grip around its B subunit. This binding undergoes partial disruption during ATP hydrolysis, potentially enabling other proteins such as mTOR to bind to the α-helix of mEAK-7. mEAK-7 also promotes chemoresistance and radiation resistance by sustaining DNA damage-mediated mTOR signaling through interactions with DNA-PKcs (DNA-dependent protein kinase catalytic subunit). Taken together, these findings indicate that mEAK-7 may be a promising therapeutic target against tumors. However, the precise molecular mechanisms and signal transduction pathways of mEAK-7 in cancer remain largely unknown, motivating the need for further investigation. Here, we summarize the current known roles of mEAK-7 in normal physiology and cancer development by reviewing the latest studies and discuss potential future developments of mEAK-7 in targeted cancer therapy.
    Keywords:  V-ATPase; cancer; lysosomal membrane protein; mEAK-7; mTOR signaling
    DOI:  https://doi.org/10.3389/fonc.2024.1375498
  13. Autophagy. 2024 Mar 28. 1-10
    TP53INP2-dependent activation of muscle autophagy ameliorates sarcopenia and promotes healthy aging.
    David Sebastián, Marc Beltrà, Andrea Irazoki, David Sala, Pilar Aparicio, Cecilia Aris, Esmaeil Alibakhshi, Maria Rubio-Valera, Manuel Palacín, Juan Castellanos, Luis Lores, Antonio Zorzano.
      Sarcopenia is a major contributor to disability in older adults, and thus, it is key to elucidate the mechanisms underlying its development. Increasing evidence suggests that impaired macroautophagy/autophagy contributes to the development of sarcopenia. However, the mechanisms leading to reduced autophagy during aging remain largely unexplored, and whether autophagy activation protects from sarcopenia has not been fully addressed. Here we show that the autophagy regulator TP53INP2/TRP53INP2 is decreased during aging in mouse and human skeletal muscle. Importantly, chronic activation of autophagy by muscle-specific overexpression of TRP53INP2 prevents sarcopenia and the decline of muscle function in mice. Acute re-expression of TRP53INP2 in aged mice also improves muscle atrophy, enhances mitophagy, and reduces ROS production. In humans, high levels of TP53INP2 in muscle are associated with increased muscle strength and healthy aging. Our findings highlight the relevance of an active muscle autophagy in the maintenance of muscle mass and prevention of sarcopenia.Abbreviation: ATG7: autophagy related 7; BMI: body mass index; EIF4EBP1: eukaryotic translation initiation factor 4E binding protein 1; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; ROS: reactive oxygen species; TP53INP2: tumor protein p53 inducible nuclear protein 2; WT: wild type.
    Keywords:  Sarcopenia; aging; autophagy; mitophagy; muscle atrophy
    DOI:  https://doi.org/10.1080/15548627.2024.2333717
  14. Cells. 2024 Mar 17. pii: 531. [Epub ahead of print]13(6):
    Bitter Taste Receptor T2R14 and Autophagy Flux in Gingival Epithelial Cells.
    Nisha Singh, Ben Ulmer, Manoj Reddy Medapati, Christine Zhang, Robert J Schroth, Saeid Ghavami, Prashen Chelikani.
      Macroautophagy (hereafter autophagy) is a lysosomal degradation pathway that functions in nutrient recycling and as a mechanism of innate immunity. Previously, we reported a novel host-bacteria interaction between cariogenic S. mutans and bitter taste receptor (T2R14) in gingival epithelial cells (GECs), leading to an innate immune response. Further, S. mutans might be using the host immune system to inhibit other Gram-positive bacteria, such as S. aureus. To determine whether these bacteria exploit the autophagic machinery of GEC, it is first necessary to evaluate the role of T2R14 in modulating autophagic flux. So far, the role of T2R14 in the regulation of autophagy is not well characterized. Therefore, in this study, for the first time, we report that T2R14 downregulates autophagy flux in GECs, and T2R14 knockout increases acidic vacuoles. However, the treatments of GEC WT with a T2R14 agonist and antagonist did not lead to a significant change in acidic vacuole formation. Transmission electron microscopy morphometric results also suggested an increased number of autophagic vesicles in T2R14-knockout GEC. Further, our results suggest that S. mutans competence stimulating peptide CSP-1 showed robust intracellular calcium release and this effect is both T2R14- and autophagy protein 7-dependent. In this study, we provide the first evidence that T2R14 modulates autophagy flux in GEC. The results of the current study could help in identifying the impact of T2R in regulation of the immuno-microenvironment of GEC and subsequently oral health.
    Keywords:  acridine orange; autophagosome; autophagy flux inhibition; bitter taste receptor; calcium; cariogenic bacteria; serum starvation
    DOI:  https://doi.org/10.3390/cells13060531
  15. Lipids Health Dis. 2024 Mar 28. 23(1): 91
    Lipid droplet accumulation in Wdr45-deficient cells caused by impairment of chaperone-mediated autophagic degradation of Fasn.
    Qiuhong Xiong, Huimin Sun, Yanlin Wang, Qian Xu, Yu Zhang, Mei Xu, Zhonghua Zhao, Ping Li, Changxin Wu.
       BACKGROUND: β-Propeller protein-associated neurodegeneration (BPAN) is a genetic neurodegenerative disease caused by mutations in WDR45. The impairment of autophagy caused by WDR45 deficiency contributes to the pathogenesis of BPAN; however, the pathomechanism of this disease is largely unknown. Lipid dyshomeostasis is involved in neurogenerative diseases, but whether lipid metabolism is affected by Wdr45 deficiency and whether lipid dyshomeostasis contributes to the progression of BPAN are unclear.
    METHODS: We generated Wdr45 knockout SN4741 cell lines using CRISPR‒Cas9-mediated genome editing, then lipid droplets (LDs) were stained using BODIPY 493/503. Chaperone-mediated autophagy was determined by RT-qPCR and western blotting. The expression of fatty acid synthase (Fasn) was detected by western blot in the presence or absence of the lysosomal inhibitor NH4Cl and the CMA activator AR7. The interaction between Fasn and HSC70 was analyzed using coimmunoprecipitation (Co-IP) assay. Cell viability was measured by a CCK-8 kit after treatment with the Fasn inhibitor C75 or the CMA activator AR7.
    RESULTS: Deletion of Wdr45 impaired chaperone-mediated autophagy (CMA), thus leading to lipid droplet (LD) accumulation. Moreover, Fasn can be degraded via CMA, and that defective CMA leads to elevated Fasn, which promotes LD formation. LD accumulation is toxic to cells; however, cell viability was not rescued by Fasn inhibition or CMA activation. Inhibition of Fasn with a low concentration of C75 did not affect cell viability but decreases LD density.
    CONCLUSIONS: These results suggested that Fasn is essential for cell survival but that excessive Fasn leads to LD accumulation in Wdr45 knockout cells.
    Keywords:  Accumulation; BPAN; CMA; Fasn; Lipid droplet; Wdr45
    DOI:  https://doi.org/10.1186/s12944-024-02088-y
  16. Cell Rep. 2024 Mar 26. pii: S2211-1247(24)00338-3. [Epub ahead of print]43(4): 114010
    RPGR is a guanine nucleotide exchange factor for the small GTPase RAB37 required for retinal function via autophagy regulation.
    Ruhong Ying, Cong Li, Huirong Li, Juan Zou, Mengxin Hu, Qiang Hong, Yin Shen, Ling Hou, Hanhua Cheng, Rongjia Zhou.
      Although the small GTPase RAB37 acts as an organizer of autophagosome biogenesis, the upstream regulatory mechanism of autophagy via guanosine diphosphate (GDP)-guanosine triphosphate (GTP) exchange in maintaining retinal function has not been determined. We found that retinitis pigmentosa GTPase regulator (RPGR) is a guanine nucleotide exchange factor that activates RAB37 by accelerating GDP-to-GTP exchange. RPGR directly interacts with RAB37 via the RPGR-RCC1-like domain to promote autophagy through stimulating exchange. Rpgr knockout (KO) in mice leads to photoreceptor degeneration owing to autophagy impairment in the retina. Notably, the retinopathy phenotypes of Rpgr KO retinas are rescued by the adeno-associated virus-mediated transfer of pre-trans-splicing molecules, which produce normal Rpgr mRNAs via trans-splicing in the Rpgr KO retinas. This rescue upregulates autophagy through the re-expression of RPGR in KO retinas to accelerate GDP-to-GTP exchange; thus, retinal homeostasis reverts to normal. Taken together, these findings provide an important missing link for coordinating RAB37 GDP-GTP exchange via the RPGR and retinal homeostasis by autophagy regulation.
    Keywords:  CP: Molecular biology; CP: Neuroscience; RAB37; autophagy; guanine nucleotide exchange factor; homeostasis; retina
    DOI:  https://doi.org/10.1016/j.celrep.2024.114010
  17. Sci Rep. 2024 03 26. 14(1): 7151
    Homocysteine metabolites inhibit autophagy by upregulating miR-21-5p, miR-155-5p, miR-216-5p, and miR-320c-3p in human vascular endothelial cells.
    Łukasz Witucki, Hieronim Jakubowski.
      Nutritional and genetic deficiencies in homocysteine (Hcy) metabolism lead to hyperhomocysteinemia (HHcy) and cause endothelial dysfunction, a hallmark of atherosclerosis, which is a major cause of cardiovascular disease (CVD). Impaired autophagy causes the accumulation of damaged proteins and organelles and is associated with CVD. Biochemically, HHcy is characterized by elevated levels of Hcy and its metabolites, Hcy-thiolactone and N-Hcy-protein. However, whether these metabolites can dysregulate mTOR signaling and autophagy in endothelial cells is not known. Here, we examined the influence of Hcy-thiolactone, N-Hcy-protein, and Hcy on autophagy human umbilical vein endothelial cells. We found that treatments with Hcy-thiolactone, N-Hcy-protein, or Hcy significantly downregulated beclin 1 (BECN1), autophagy-related 5 (ATG5), autophagy-related 7 (ATG7), and microtubule-associated protein 1 light chain 3 (LC3) mRNA and protein levels. We also found that these changes were mediated by upregulation by Hcy-thiolactone, N-Hcy-protein, and Hcy of autophagy-targeting microRNA (miR): miR-21, miR-155, miR-216, and miR-320c. The effects of these metabolites on levels of miR targeting autophagy as well as on the levels of BECN1, ATG5, ATG7, and LC3 mRNA and protein were abrogated by treatments with inhibitors of miR-21, miR-155, miR-216, and mir320c. Taken together, our findings show that Hcy metabolites can upregulate miR-21, miR-155, miR-216, and mir320c, which then downregulate autophagy in human endothelial cells, important for vascular homeostasis.
    Keywords:  Autophagy; Endothelial dysfunction; HUVEC; Homocysteine metabolites; microRNA
    DOI:  https://doi.org/10.1038/s41598-024-57750-3
  18. Nat Commun. 2024 Mar 27. 15(1): 2676
    Autophagy-mediated degradation of integumentary tapetum is critical for embryo pattern formation.
    Lin-Lin Zhao, Ru Chen, Ziyu Bai, Junyi Liu, Yuhao Zhang, Yicheng Zhong, Meng-Xiang Sun, Peng Zhao.
      Autophagy modulates the degradation and recycling of intracellular materials and contributes to male gametophyte development and male fertility in plants. However, whether autophagy participates in seed development remains largely unknown. Here, we demonstrate that autophagy is crucial for timely programmed cell death (PCD) in the integumentary tapetum, the counterpart of anther tapetum, influencing embryo pattern formation and seed viability. Inhibition of autophagy resulted in delayed PCD of the integumentary tapetum and defects in embryo patterning. Cell-type-specific restoration of autophagic activities revealed that the integumentary tapetum plays a non-autonomous role in embryo patterning. Furthermore, high-throughput, comprehensive lipidomic analyzes uncovered an unexpected seed-developmental-stage-dependent role of autophagy in seed lipid metabolism: it contributes to triacylglycerol degradation before fertilization and to triacylglycerol biosynthesis after fertilization. This study highlights the critical role of autophagy in regulating timely integumentary tapetum PCD and reveals its significance in seed lipid metabolism and viability.
    DOI:  https://doi.org/10.1038/s41467-024-46902-8
  19. Autophagy. 2024 Mar 27. 1-16
    Design and validation of a reporter mouse to study the dynamic regulation of TFEB and TFE3 activity through in vivo imaging techniques.
    Electra Brunialti, Nicoletta Rizzi, Rita Pinto-Costa, Alessandro Villa, Alessia Panzeri, Clara Meda, Monica Rebecchi, Donato A Di Monte, Paolo Ciana.
      TFEB and TFE3 belong to the MiT/TFE family of transcription factors that bind identical DNA responsive elements in the regulatory regions of target genes. They are involved in regulating lysosomal biogenesis, function, exocytosis, autophagy, and lipid catabolism. Precise control of TFEB and TFE3 activity is crucial for processes such as senescence, stress response, energy metabolism, and cellular catabolism. Dysregulation of these factors is implicated in various diseases, thus researchers have explored pharmacological approaches to modulate MiT/TFE activity, considering these transcription factors as potential therapeutic targets. However, the physiological complexity of their functions and the lack of suitable in vivo tools have limited the development of selective MiT/TFE modulating agents. Here, we have created a reporter-based biosensor, named CLEARoptimized, facilitating the pharmacological profiling of TFEB- and TFE3-mediated transcription. This innovative tool enables the measurement of TFEB and TFE3 activity in living cells and mice through imaging and biochemical techniques. CLEARoptimized consists of a promoter with six coordinated lysosomal expression and regulation motifs identified through an in-depth bioinformatic analysis of the promoters of 128 TFEB-target genes. The biosensor drives the expression of luciferase and tdTomato reporter genes, allowing the quantification of TFEB and TFE3 activity in cells and in animals through optical imaging and biochemical assays. The biosensor's validity was confirmed by modulating MiT/TFE activity in both cell culture and reporter mice using physiological and pharmacological stimuli. Overall, this study introduces an innovative tool for studying autophagy and lysosomal pathway modulation at various biological levels, from individual cells to the entire organism.Abbreviations: CLEAR: coordinated lysosomal expression and regulation; MAR: matrix attachment regions; MiT: microphthalmia-associated transcription factor; ROI: region of interest; TBS: tris-buffered saline; TF: transcription factor; TFE3: transcription factor binding to IGHM enhancer 3; TFEB: transcription factor EB; TH: tyrosine hydroxylase; TK: thymidine kinase; TSS: transcription start site.
    Keywords:  Autophagy; drug discovery; luciferase; lysosomal pathway; non-invasive study of TFEB and TFE3; optical imaging
    DOI:  https://doi.org/10.1080/15548627.2024.2334111
  20. Biomolecules. 2024 Feb 20. pii: 248. [Epub ahead of print]14(3):
    Cloflucarban Illuminates Specificity and Context-Dependent Activation of the PINK1-Parkin Pathway by Mitochondrial Complex Inhibition.
    Adrian T Ramirez, Zeyu Liu, Quanbin Xu, Sarah Nowosadtko, Xuedong Liu.
      The PTEN-induced kinase 1 (PINK1)-Parkin pathway plays a vital role in maintaining a healthy pool of mitochondria in higher eukaryotic cells. While the downstream components of this pathway are well understood, the upstream triggers remain less explored. In this study, we conducted an extensive analysis of inhibitors targeting various mitochondrial electron transport chain (ETC) complexes to investigate their potential as activators of the PINK1-Parkin pathway. We identified cloflucarban, an antibacterial compound, as a novel pathway activator that simultaneously inhibits mitochondrial complexes III and V, and V. RNA interference (RNAi) confirmed that the dual inhibition of these complexes activates the PINK1-Parkin pathway. Intriguingly, we discovered that albumin, specifically bovine serum albumin (BSA) and human serum albumin (HSA) commonly present in culture media, can hinder carbonyl cyanide m-chlorophenyl hydrazone (CCCP)-induced pathway activation. However, cloflucarban's efficacy remains unaffected by albumin, highlighting its reliability for studying the PINK1-Parkin pathway. This study provides insights into the activation of the upstream PINK1-Parkin pathway and underscores the influence of culture conditions on research outcomes. Cloflucarban emerges as a promising tool for investigating mitochondrial quality control and neurodegenerative diseases.
    Keywords:  CCCP; PINK1; Parkin; bovine serum albumin; cloflucarban; complex V; electron transport complex III; human serum albumin; mitochondrial quality control; mitophagy
    DOI:  https://doi.org/10.3390/biom14030248
  21. Int J Mol Sci. 2024 Mar 09. pii: 3145. [Epub ahead of print]25(6):
    Negative Regulation of Autophagy during Macrophage Infection by Mycobacterium bovis BCG via Protein Kinase C Activation.
    Rafael Maldonado-Bravo, Tomás Villaseñor, Martha Pedraza-Escalona, Leonor Pérez-Martínez, Rogelio Hernández-Pando, Gustavo Pedraza-Alva.
      Mycobacterium tuberculosis (Mtb) employs various strategies to manipulate the host's cellular machinery, overriding critical molecular mechanisms such as phagosome-lysosome fusion, which are crucial for its destruction. The Protein Kinase C (PKC) signaling pathways play a key role in regulating phagocytosis. Recent research in Interferon-activated macrophages has unveiled that PKC phosphorylates Coronin-1, leading to a shift from phagocytosis to micropinocytosis, ultimately resulting in Mtb destruction. Therefore, this study aims to identify additional PKC targets that may facilitate Mycobacterium bovis (M. bovis) infection in macrophages. Protein extracts were obtained from THP-1 cells, both unstimulated and mycobacterial-stimulated, in the presence or absence of a general PKC inhibitor. We conducted an enrichment of phosphorylated peptides, followed by their identification through mass spectrometry (LC-MS/MS). Our analysis revealed 736 phosphorylated proteins, among which 153 exhibited alterations in their phosphorylation profiles in response to infection in a PKC-dependent manner. Among these 153 proteins, 55 are involved in various cellular processes, including endocytosis, vesicular traffic, autophagy, and programmed cell death. Importantly, our findings suggest that PKC may negatively regulate autophagy by phosphorylating proteins within the mTORC1 pathway (mTOR2/PKC/Raf-1/Tsc2/Raptor/Sequestosome-1) in response to M. bovis BCG infection, thereby promoting macrophage infection.
    Keywords:  M. bovis; M. tuberculosis; PKC; autophagy; macrophage
    DOI:  https://doi.org/10.3390/ijms25063145
  22. Cell Death Differ. 2024 Mar 22.
    Mitophagy mediated by BNIP3 and NIX protects against ferroptosis by downregulating mitochondrial reactive oxygen species.
    Shun-Ichi Yamashita, Yuki Sugiura, Yuta Matsuoka, Rae Maeda, Keiichi Inoue, Kentaro Furukawa, Tomoyuki Fukuda, David C Chan, Tomotake Kanki.
      Mitophagy plays an important role in the maintenance of mitochondrial homeostasis and can be categorized into two types: ubiquitin-mediated and receptor-mediated pathways. During receptor-mediated mitophagy, mitophagy receptors facilitate mitophagy by tethering the isolation membrane to mitochondria. Although at least five outer mitochondrial membrane proteins have been identified as mitophagy receptors, their individual contribution and interrelationship remain unclear. Here, we show that HeLa cells lacking BNIP3 and NIX, two of the five receptors, exhibit a complete loss of mitophagy in various conditions. Conversely, cells deficient in the other three receptors show normal mitophagy. Using BNIP3/NIX double knockout (DKO) cells as a model, we reveal that mitophagy deficiency elevates mitochondrial reactive oxygen species (mtROS), which leads to activation of the Nrf2 antioxidant pathway. Notably, BNIP3/NIX DKO cells are highly sensitive to ferroptosis when Nrf2-driven antioxidant enzymes are compromised. Moreover, the sensitivity of BNIP3/NIX DKO cells is fully rescued upon the introduction of wild-type BNIP3 and NIX, but not the mutant forms incapable of facilitating mitophagy. Consequently, our results demonstrate that BNIP3 and NIX-mediated mitophagy plays a role in regulating mtROS levels and protects cells from ferroptosis.
    DOI:  https://doi.org/10.1038/s41418-024-01280-y
  23. Eur J Clin Invest. 2024 Mar 26. e14199
    Mitophagy modulation for the treatment of cardiovascular diseases.
    Italian Society of Cardiology Working Group on Cellular and Molecular Biology of the Heart
       BACKGROUND: Defects of mitophagy, the selective form of autophagy for mitochondria, are commonly observed in several cardiovascular diseases and represent the main cause of mitochondrial dysfunction. For this reason, mitophagy has emerged as a novel and potential therapeutic target.
    METHODS: In this review, we discuss current evidence about the biological significance of mitophagy in relevant preclinical models of cardiac and vascular diseases, such as heart failure, ischemia/reperfusion injury, metabolic cardiomyopathy and atherosclerosis.
    RESULTS: Multiple studies have shown that cardiac and vascular mitophagy is an adaptive mechanism in response to stress, contributing to cardiovascular homeostasis. Mitophagy defects lead to cell death, ultimately impairing cardiac and vascular function, whereas restoration of mitophagy by specific compounds delays disease progression.
    CONCLUSIONS: Despite previous efforts, the molecular mechanisms underlying mitophagy activation in response to stress are not fully characterized. A comprehensive understanding of different forms of mitophagy active in the cardiovascular system is extremely important for the development of new drugs targeting this process. Human studies evaluating mitophagy abnormalities in patients at high cardiovascular risk also represent a future challenge.
    Keywords:  autophagy; heart failure; metabolic cardiomyopathy; mitochondrial dysfunction; mitophagy; myocardial ischemia
    DOI:  https://doi.org/10.1111/eci.14199
  24. Neuroreport. 2024 Mar 04.
    Impaired autophagic flux in the human brain after traumatic brain injury.
    Jiadong Lang, Boyu Sun, Shiyao Feng, Guozhu Sun.
      Emerging evidence indicates that dysfunctional autophagic flux significantly contributes to the pathology of experimental traumatic brain injury (TBI). The current study aims to clarify its role post-TBI using brain tissues from TBI patients. Histological examinations, including hematoxylin and eosin, Nissl staining, and brain water content analysis, were employed to monitor brain damage progression. Electron microscopy was used to visualize autophagic vesicles. Western blotting and immunohistochemistry were performed to analyze the levels of important autophagic flux-related proteins such as Beclin1, autophagy-related protein 5, lipidated microtubule-associated protein light-chain 3 (LC3-II), autophagic substrate sequestosome 1 (SQSTM1/p62), and cathepsin D (CTSD), a lysosomal enzyme. Immunofluorescence assays evaluated LC3 colocalization with NeuN, P62, or CTSD, and correlation analysis linked autophagy-related protein levels with brain water content and Nissl bodies. Early-stage TBI results showed increased autophagic vesicles and LC3-positive neurons, suggesting autophagosome accumulation due to enhanced initiation and reduced clearance. As TBI progressed, LC3-II and P62 levels increased, while CTSD levels decreased. This indicates autophagosome overload from impaired degradation rather than increased initiation. The study reveals a potential association between worsening brain damage and impaired autophagic flux post-TBI, positioning improved autophagic flux as a viable therapeutic target for TBI.
    DOI:  https://doi.org/10.1097/WNR.0000000000002020
  25. Exp Parasitol. 2024 Mar 21. pii: S0014-4894(24)00048-1. [Epub ahead of print]260 108745
    Elucidating miR-146a-3p as a key player in autophagy and lipid metabolism in Leishmania major infection.
    Prajakta Ingale, Shailza Singh.
      Autophagy is a key step involved in many unicellular eukaryotic diseases, including leishmaniasis, for cellular remodelling and differentiation during parasite's lifecycle. Lipids play a significant role in the infection process that begins with Leishmania major invading host cells. MicroRNAs (miRNAs), a family of small, 22-24 nucleotide noncoding regulatory RNAs, target mRNAs to modify gene expression and, subsequently, proteome output may have a regulatory role in altering the host cell processes. We observed miR-146a-3p expression increases in a time-dependent manner post Leishmania major infection. Transfecting miR-146a-3p mimic increases the expression of ATG7, an autophagy gene that encodes an E1-like enzyme in two ubiquitin-like conjugation systems required for autophagosome progression. HPGD (15-hydroxyprostaglandin dehydrogenase) operates as an enzyme, converting prostaglandin to its non-active form. Microarray data and western studies reveal that miR-146a-3p targets and inhibits HPGD, thereby increasing prostaglandin activity in lipid droplets. Herein, our research focuses on miR-146a-3p, which boosts ATG7 expression while reducing HPGD post Leishmania major infections helping us comprehend the intricate network of microRNA, autophagy, and lipid metabolism in leishmaniasis.
    Keywords:  ATG7; Autophagy; HPGD; Leishmania major; Lipid droplets; THP-1 cells; microRNAs
    DOI:  https://doi.org/10.1016/j.exppara.2024.108745
  26. Metabolism. 2024 Mar 26. pii: S0026-0495(24)00131-8. [Epub ahead of print] 155905
    Interplay of CD36, autophagy, and lipid metabolism: insights into cancer progression.
    Yuxuan Yang, Xiaokun Liu, Di Yang, Lianhui Li, Sheng Li, Sen Lu, Ning Li.
      CD36, a scavenger receptor B2 that is dynamically distributed between cell membranes and organelle membranes, plays a crucial role in regulating lipid metabolism. Abnormal CD36 activity has been linked to a range of metabolic disorders, such as obesity, nonalcoholic fatty liver disease, insulin resistance and cardiovascular disease. CD36 undergoes various modifications, including palmitoylation, glycosylation, and ubiquitination, which greatly affect its binding affinity to various ligands, thereby triggering and influencing various biological effects. In the context of tumors, CD36 interacts with autophagy to jointly regulate tumorigenesis, mainly by influencing the tumor microenvironment. The central role of CD36 in cellular lipid homeostasis and recent molecular insights into CD36 in tumor development indicate the applicability of CD36 as a therapeutic target for cancer treatment. Here, we discuss the diverse posttranslational modifications of CD36 and their respective roles in lipid metabolism. Additionally, we delve into recent research findings on CD36 in tumors, outlining ongoing drug development efforts targeting CD36 and potential strategies for future development and highlighting the interplay between CD36 and autophagy in the context of cancer. Our aim is to provide a comprehensive understanding of the function of CD36 in both physiological and pathological processes, facilitating a more in-depth analysis of cancer progression and a better development and application of CD36-targeting drugs for tumor therapy in the near future.
    Keywords:  Autophagy; CD36; Lipid metabolism; Palmitoylation; Tumor immunity; cancer
    DOI:  https://doi.org/10.1016/j.metabol.2024.155905
  27. Bioorg Med Chem Lett. 2024 Mar 22. pii: S0960-894X(24)00115-X. [Epub ahead of print]104 129713
    Antiproliferative activities through accelerating autophagic flux by basidalin and its analogs in human cancer cells.
    Tomoe Matagawa, Yukiko Sasazawa, Koki Agui, Motoki Fujimaki, Sayaka Kawano, Akihiro Ogura, Ken-Ichi Takao, Masayuki Igarashi, Siro Simizu.
      Basidalin, isolated from the basidiomycete Leucoagaricus naucina, has previously demonstrated antibacterial and antitumor properties against murine cancer cells in vivo, but its effects on human cancer cells remain unknown. In this study, we found that basidalin possesses antiproliferative activity against human cancer cell lines. To elucidate the antiproliferative mechanism of basidalin, we focused on autophagy. Treatment with basidalin led to an increase in LC3-II expression level, and accelerated autophagic flux through an mTOR-independent pathway. Moreover, according to the structure-activity relationship analysis-including newly synthesized basidalin analogs-the formyl group, not the amino group, contributes to the antiproliferative activities of basidalin against human cancer cells. Additionally, the antiproliferative activity of basidalin analogs was strongly correlated with autophagy-inducing activity, indicating that basidalin exhibits antiproliferative activity through autophagy induction. These data suggest that basidalin, characterized by its ability to upregulate autophagic flux, emerges as a novel anticancer drug.
    Keywords:  Antibiotic; Antiproliferative activity; Autophagy inducer; Basidalin; Structure–activity relationship; mTOR signal
    DOI:  https://doi.org/10.1016/j.bmcl.2024.129713
  28. Int Immunopharmacol. 2024 Mar 28. pii: S1567-5769(24)00428-4. [Epub ahead of print]132 111910
    Rapamycin alleviates mitochondrial dysfunction in anti-NMDAR encephalitis mice.
    Liangbo Kong, Xiaxin Yang, Anqi Sun, Xue Yang, Xiuhe Zhao, Shengjun Wang.
      Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is one of the most prevalent forms of autoimmune encephalitis, characterized by a series of neurological and psychiatric symptoms, including cognitive impairment, seizures and psychosis. The underlying mechanism of anti-NMDAR encephalitis remains unclear. In the current study, the mouse model of anti-NMDAR encephalitis with active immunization was performed. We first uncovered excessive mitochondrial fission in the hippocampus and temporal cortex of anti-NMDAR encephalitis mice, indicated by elevated level of Phospho-DRP1 (Ser616) (p-Drp1-S616). Moreover, blockade of the autophagic flux was also demonstrated, leading to the accumulation of fragmented mitochondria, and elevated levels of mitochondrial reactive oxygen species (mtROS) and mitochondrial DNA (mtDNA) in anti-NMDAR encephalitis. More importantly, we found that the mTOR signaling pathway was overactivated, which could aggravate mitochondrial fission and inhibit autophagy, resulting in mitochondrial dysfunction. While rapamycin, the specific inhibitor of the mTOR signaling pathway, significantly alleviated mitochondrial dysfunction by inhibiting mitochondrial fission and enhancing autophagy. Levels of mtROS and mtDNA were markedly reduced after the treatment of rapamycin. In addition, rapamycin also significantly alleviated cognitive dysfunction and anxious behaviors found in anti-NMDAR encephalitis mice. Thus, our study reveals the vital role of mitochondrial dysfunction in pathological mechanism of anti-NMDAR encephalitis and lays a theoretical foundation for rapamycin to become a clinically targeted drug for anti-NMDAR encephalitis.
    Keywords:  Autophagy; Mitochondrial dysfunction; Mitochondrial fission; Rapamycin; anti-NMDAR encephalitis; mTOR signaling
    DOI:  https://doi.org/10.1016/j.intimp.2024.111910
  29. J Cell Biol. 2024 Jun 03. pii: e202305038. [Epub ahead of print]223(6):
    The GTPase activating protein Gyp7 regulates Rab7/Ypt7 activity on late endosomes.
    Nadia Füllbrunn, Raffaele Nicastro, Muriel Mari, Janice Griffith, Eric Herrmann, René Rasche, Ann-Christin Borchers, Kathrin Auffarth, Daniel Kümmel, Fulvio Reggiori, Claudio De Virgilio, Lars Langemeyer, Christian Ungermann.
      Organelles of the endomembrane system contain Rab GTPases as identity markers. Their localization is determined by guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs). It remains largely unclear how these regulators are specifically targeted to organelles and how their activity is regulated. Here, we focus on the GAP Gyp7, which acts on the Rab7-like Ypt7 protein in yeast, and surprisingly observe the protein exclusively in puncta proximal to the vacuole. Mistargeting of Gyp7 to the vacuole strongly affects vacuole morphology, suggesting that endosomal localization is needed for function. In agreement, efficient endolysosomal transport requires Gyp7. In vitro assays reveal that Gyp7 requires a distinct lipid environment for membrane binding and activity. Overexpression of Gyp7 concentrates Ypt7 in late endosomes and results in resistance to rapamycin, an inhibitor of the target of rapamycin complex 1 (TORC1), suggesting that these late endosomes are signaling endosomes. We postulate that Gyp7 is part of regulatory machinery involved in late endosome function.
    DOI:  https://doi.org/10.1083/jcb.202305038
  30. Sci Signal. 2024 Mar 26. 17(829): eadk8249
    Glucosylceramide accumulation in microglia triggers STING-dependent neuroinflammation and neurodegeneration in mice.
    Rui Wang, Hongyang Sun, Yifan Cao, Zhixiong Zhang, Yajing Chen, Xiying Wang, Lele Liu, Jin Wu, Hao Xu, Dan Wu, Chenchen Mu, Zongbing Hao, Song Qin, Haigang Ren, Junhai Han, Ming Fang, Guanghui Wang.
      Mutations in the gene encoding the lysosomal enzyme glucocerebrosidase (GCase) are responsible for Gaucher disease (GD) and are considered the strongest genetic risk factor for Parkinson's disease (PD) and Lewy body dementia (LBD). GCase deficiency leads to extensive accumulation of glucosylceramides (GCs) in cells and contributes to the neuropathology of GD, PD, and LBD by triggering chronic neuroinflammation. Here, we investigated the mechanisms by which GC accumulation induces neuroinflammation. We found that GC accumulation within microglia induced by pharmacological inhibition of GCase triggered STING-dependent inflammation, which contributed to neuronal loss both in vitro and in vivo. GC accumulation in microglia induced mitochondrial DNA (mtDNA) leakage to the cytosol to trigger STING-dependent inflammation. Rapamycin, a compound that promotes lysosomal activity, improved mitochondrial function, thereby decreasing STING signaling. Furthermore, lysosomal damage caused by GC accumulation led to defects in the degradation of activated STING, further exacerbating inflammation mediated by microglia. Thus, limiting STING activity may be a strategy to suppress neuroinflammation caused by GCase deficiency.
    DOI:  https://doi.org/10.1126/scisignal.adk8249
  31. Sci Total Environ. 2024 Mar 27. pii: S0048-9697(24)02160-0. [Epub ahead of print] 172017
    L-arginine alleviates heat stress-induced mammary gland injury through modulating CASTOR1-mTORC1 axis mediated mitochondrial homeostasis.
    Zhongchao Gai, Songhao Hu, Yujiao He, Sijia Yan, Ranran Wang, Guoli Gong, Jieqiong Zhao.
      As global warming intensifies, extreme heat is becoming increasingly frequent. These extreme heatwaves have decreased the milk production of dairy animals such as cows and goats and have caused significant damage to the entire dairy industry. It is known that heat stress (HS) can induce the apoptosis and autophagy of mammary epithelial cells (MECs), leading to a decrease in lactating MECs. L-arginine can effectively attenuate HS-induced decreases in milk yield, but the exact mechanisms are not fully understood. In this study, we found that HS upregulated the arginine sensor CASTOR1 in mouse MECs. Arginine activated mTORC1 activity through CASTOR1 and promoted mitochondrial biogenesis through the mTORC1/PGC-1α/NRF1 pathway. Moreover, arginine inhibited mitophagy through the CASTOR1/PINK1/Parkin pathway. Mitochondrial homeostasis ensures ATP synthesis and a stable cellular redox state for MECs under HS, further alleviating HS-induced damage and improving the lactation performance of MECs. In conclusion, these findings reveal the molecular mechanisms by which L-arginine relieves HS-induced mammary gland injury, and suggest that the intake of arginine-based feeds or feed additives is a promising method to increase the milk yield of dairy animals in extreme heat conditions.
    Keywords:  CASTOR1; Climate change; Heat stress; L-arginine; Mitochondrial homeostasis; mTORC1 signaling
    DOI:  https://doi.org/10.1016/j.scitotenv.2024.172017
  32. Int J Mol Sci. 2024 Mar 09. pii: 3153. [Epub ahead of print]25(6):
    Research Progress on Lipophagy-Mediated Exercise Intervention in Non-Alcoholic Fatty Liver Disease.
    Xi Li, Yangjun Yang, Yi Sun, Shuzhe Ding.
      Lipophagy is a cellular pathway targeting the lysosomal degradation of lipid droplets, playing a role in promoting lipid turnover and renewal. Abnormal lipophagy processes can lead to the occurrence and development of non-alcoholic fatty liver disease (NAFLD), characterized by the deposition of lipid droplets (LDs) in the liver. The importance of exercise training in preventing and improving NAFLD has been well-established, but the exact mechanisms remain unclear. Recent research findings suggest that lipophagy may serve as a crucial hub for liver lipid turnover under exercise conditions. Exercise may alleviate hepatic lipid accumulation and mitigate inflammatory responses and fibrosis through lipophagy, thereby improving the onset and progression of NAFLD.
    Keywords:  exercise; lipophagy; non-alcoholic fatty liver
    DOI:  https://doi.org/10.3390/ijms25063153
  33. Anal Methods. 2024 Mar 27.
    A pH-response-based fluorescent probe for detecting the mitophagy process by tracing changes in colocalization coefficients.
    Nongyi Hao, Zekun Jiang, Lina Zhou, Xiaoyu Dai, Xiuqi Kong.
      Mitochondria are not only the center of energy metabolism but also involved in regulating cellular activities. Quality and quantity control of mitochondria is therefore essential. Mitophagy is a lysosome-dependent process to clear dysfunctional mitochondria, and abnormal mitophagy can cause metabolic disorders. Therefore, it is necessary to monitor the mitophagy in living cells on a real-time basis. Herein, we developed a pH-responsive fluorescent probe MP for the detection of the mitophagy process using real-time tracing colocalization coefficients. Probe MP showed good pH responses with high selectivity and sensitivity in spectral testing. Probe MP is of positive charge, which is beneficial for accumulating into mitochondrial in living cells. Cells exhibited pH-dependent fluorescence when they were treated with different pH media. Importantly, the changes in the colocalization coefficient between probe MP and Lyso Tracker® Deep Red from 0.4 to 0.8 were achieved in a real-time manner during the mitophagy stimulated by CCCP, starvation and rapamycin. Therefore, combined with the parameter of the colocalization coefficient, probe MP is a potential molecular tool for the real-time tracing of mitophagy to further explore the details of mitophagy.
    DOI:  https://doi.org/10.1039/d4ay00211c
  34. Prog Biophys Mol Biol. 2024 Mar 24. pii: S0079-6107(24)00034-8. [Epub ahead of print]
    The dysregulated autophagy in osteoarthritis: Revisiting molecular profile.
    Liang Liu, Jie Wang, Lu Liu, Wenling Shi, Huajie Gao, Lun Liu.
      The risk factors of osteoarthritis (OA) are different and obesity, lifestyle, inflammation, cell death mechanisms and diabetes mellitus are among them. The changes in the biological mechanisms are considered as main regulators of OA pathogenesis. The dysregulation of autophagy is observed in different human diseases. During the pathogenesis of OA, the autophagy levels (induction or inhibition) change. The supportive and pro-survival function of autophagy can retard the progression of OA. The protective autophagy prevents the cartilage degeneration. Moreover, autophagy demonstrates interactions with cell death mechanisms and through inhibition of apoptosis and necroptosis, it improves OA. The non-coding RNA molecules can regulate autophagy and through direct and indirect control of autophagy, they dually delay/increase OA pathogenesis. The mitochondrial integrity can be regulated by autophagy to alleviate OA. Furthermore, therapeutic compounds, especially phytochemicals, stimulate protective autophagy in chondrocytes to prevent cell death. The protective autophagy has ability of reducing inflammation and oxidative damage, as two key players in the pathogenesis of OA.
    Keywords:  Apoptosis and autophagy; Autophagy; Inflammation; Non-coding RNAs; Osteoarthritis
    DOI:  https://doi.org/10.1016/j.pbiomolbio.2024.03.004
  35. Proc Natl Acad Sci U S A. 2024 Apr 02. 121(14): e2321612121
    Autophagy maintains endosperm quality during seed storage to preserve germination ability in Arabidopsis.
    Daiki Shinozaki, Erina Takayama, Naoto Kawakami, Kohki Yoshimoto.
      To preserve germination ability, plant seeds must be protected from environmental stresses during the storage period. Here, we demonstrate that autophagy, an intracellular degradation system, maintains seed germination ability in Arabidopsis thaliana. The germination ability of long-term (>5 years) stored dry seeds of autophagy-defective (atg) mutant and wild-type (WT) plants was compared. Long-term stored (old) seeds of atg mutants showed lower germination ability than WT seeds, although short-term stored (new) seeds of atg mutants did not show such a phenotype. After removal of the seed coat and endosperm from old atg mutant seeds, the embryos developed into seedlings. Autophagic flux was maintained in endosperm cells during the storage period, and autophagy defect resulted in the accumulation of oxidized proteins and accelerated endosperm cell death. Consistent with these findings, the transcripts of genes, ENDO-β-MANNANASE 7 and EXPANSIN 2, which are responsible for degradation/remodeling of the endosperm cell wall during germination, were reduced in old atg mutant seeds. We conclude that autophagy maintains endosperm quality during seed storage by suppressing aging-dependent oxidative damage and cell death, which allows the endosperm to perform optimal functions during germination, i.e., cell wall degradation/remodeling, even after long-term storage.
    Keywords:  Arabidopsis thaliana; autophagy; endosperm; germination ability; long-term seed storage
    DOI:  https://doi.org/10.1073/pnas.2321612121
  36. Biomolecules. 2024 Mar 19. pii: 365. [Epub ahead of print]14(3):
    In Silico Investigation of Parkin-Activating Mutations Using Simulations and Network Modeling.
    Naeyma N Islam, Caleb A Weber, Matt Coban, Liam T Cocker, Fabienne C Fiesel, Wolfdieter Springer, Thomas R Caulfield.
      Complete loss-of-function mutations in the PRKN gene are a major cause of early-onset Parkinson's disease (PD). PRKN encodes the Parkin protein, an E3 ubiquitin ligase that works in conjunction with the ubiquitin kinase PINK1 in a distinct quality control pathway to tag damaged mitochondria for autophagic clearance, i.e., mitophagy. According to previous structural investigations, Parkin protein is typically kept in an inactive conformation via several intramolecular, auto-inhibitory interactions. Here, we performed molecular dynamics simulations (MDS) to provide insights into conformational changes occurring during the de-repression of Parkin and the gain of catalytic activity. We analyzed four different Parkin-activating mutations that are predicted to disrupt certain aspects of its auto-inhibition. All four variants showed greater conformational motions compared to wild-type protein, as well as differences in distances between domain interfaces and solvent-accessible surface area, which are thought to play critical roles as Parkin gains catalytic activity. Our findings reveal that the studied variants exert a notable influence on Parkin activation as they alter the opening of its closed inactive structure, a finding that is supported by recent structure- and cell-based studies. These findings not only helped further characterize the hyperactive variants but overall improved our understanding of Parkin's catalytic activity and nominated targets within Parkin's structure for potential therapeutic designs.
    Keywords:  Parkinson’s disease; molecular dynamics simulation; network modeling; parkin
    DOI:  https://doi.org/10.3390/biom14030365
  37. Nat Commun. 2024 Mar 22. 15(1): 2553
    SNX8 enables lysosome reformation and reverses lysosomal storage disorder.
    Xinran Li, Cong Xiang, Shilei Zhu, Jiansheng Guo, Chang Liu, Ailian Wang, Jin Cao, Yan Lu, Dante Neculai, Pinglong Xu, Xin-Hua Feng.
      Lysosomal Storage Disorders (LSDs), which share common phenotypes, including enlarged lysosomes and defective lysosomal storage, are caused by mutations in lysosome-related genes. Although gene therapies and enzyme replacement therapies have been explored, there are currently no effective routine therapies against LSDs. During lysosome reformation, which occurs when the functional lysosome pool is reduced, lysosomal lipids and proteins are recycled to restore lysosome functions. Here we report that the sorting nexin protein SNX8 promotes lysosome tubulation, a process that is required for lysosome reformation, and that loss of SNX8 leads to phenotypes characteristic of LSDs in human cells. SNX8 overexpression rescued features of LSDs in cells, and AAV-based delivery of SNX8 to the brain rescued LSD phenotypes in mice. Importantly, by screening a natural compound library, we identified three small molecules that enhanced SNX8-lysosome binding and reversed LSD phenotypes in human cells and in mice. Altogether, our results provide a potential solution for the treatment of LSDs.
    DOI:  https://doi.org/10.1038/s41467-024-46705-x
  38. Mar Drugs. 2024 Mar 08. pii: 127. [Epub ahead of print]22(3):
    Induction of Autophagy by Extract from Corydalis heterocarpa for Skin Anti-Aging.
    Kyeong Eun Yang, Soo-Bin Nam, Ga-Eun Lee, Gabsik Yang, Mee-Hyun Lee, Geul Bang, Jung Hoon Choi, Yong-Yeon Cho, Cheol-Jung Lee.
      The extracts of Corydalis heterocarpa, a salt-tolerant plant, exhibit diverse physiological properties, including anti-inflammatory, anticancer, and antiadipogenic effects. However, the anti-aging effects of C. heterocarpa extract (CHE) on human skin cells have not yet been investigated. In the present study, we determined that CHE inhibited senescence-associated β-galactosidase (SA-β-gal)-stained senescent human dermal fibroblasts (HDFs). Furthermore, CHE markedly suppressed the expression of major regulatory proteins involved in senescence, including p53, p21, and caveolin-1. Interestingly, CHE promoted autophagic flux, as confirmed by the formation of microtubule-associated protein 1 light chain 3B (LC3B) puncta and lysosomal activity. Notably, using RNA sequencing (RNA-seq), we showed that CHE selectively regulated the gene expression of leucine-rich repeat and sterile alpha motif-containing 1 (LRSAM1), an important regulator of autophagy. The adenosine-monophosphate activated protein kinase/mammalian target of rapamycin (AMPK/mTOR) pathway, which is essential for autophagy regulation, was also modulated by CHE. LRSAM1 depletion not only inhibited LC3B expression but also decreased the autophagy flux induced by CHE. Moreover, the knockdown of LRSAM1 suppressed the reversal of CHE-induced senescence in old HDFs. Collectively, our study has revealed the rejuvenating effects and molecular mechanisms of CHE, suggesting that CHE may be a promising anti-aging agent.
    Keywords:  Corydalis heterocarpa; LRSAM1; anti-aging; autophagy; cellular senescence
    DOI:  https://doi.org/10.3390/md22030127
  39. Nature. 2024 Mar 27.
    The HEAT repeat protein HPO-27 is a lysosome fission factor.
    Letao Li, Xilu Liu, Shanshan Yang, Meijiao Li, Yanwei Wu, Siqi Hu, Wenjuan Wang, Amin Jiang, Qianqian Zhang, Junbing Zhang, Xiaoli Ma, Junyan Hu, Qiaohong Zhao, Yubing Liu, Dong Li, Junjie Hu, Chonglin Yang, Wei Feng, Xiaochen Wang.
      Lysosomes are degradation and signalling centres crucial for homeostasis, development and ageing1. To meet diverse cellular demands, lysosomes remodel their morphology and function through constant fusion and fission2,3. Little is known about the molecular basis of fission. Here we identify HPO-27, a conserved HEAT repeat protein, as a lysosome scission factor in Caenorhabditis elegans. Loss of HPO-27 impairs lysosome fission and leads to an excessive tubular network that ultimately collapses. HPO-27 and its human homologue MROH1 are recruited to lysosomes by RAB-7 and enriched at scission sites. Super-resolution imaging, negative-staining electron microscopy and in vitro reconstitution assays reveal that HPO-27 and MROH1 self-assemble to mediate the constriction and scission of lysosomal tubules in worms and mammalian cells, respectively, and assemble to sever supported membrane tubes in vitro. Loss of HPO-27 affects lysosomal morphology, integrity and degradation activity, which impairs animal development and longevity. Thus, HPO-27 and MROH1 act as self-assembling scission factors to maintain lysosomal homeostasis and function.
    DOI:  https://doi.org/10.1038/s41586-024-07249-8
  40. Acta Neuropathol. 2024 Mar 25. 147(1): 62
    Loss of TMEM106B exacerbates Tau pathology and neurodegeneration in PS19 mice.
    Tuancheng Feng, Huan Du, Cha Yang, Ya Wang, Fenghua Hu.
      TMEM106B, a gene encoding a lysosome membrane protein, is tightly associated with brain aging, hypomyelinating leukodystrophy, and multiple neurodegenerative diseases, including frontotemporal lobar degeneration with TDP-43 aggregates (FTLD-TDP). Recently, TMEM106B polymorphisms have been associated with tauopathy in chronic traumatic encephalopathy (CTE) and FTLD-TDP patients. However, how TMEM106B influences Tau pathology and its associated neurodegeneration, is unclear. Here we show that loss of TMEM106B enhances the accumulation of pathological Tau, especially in the neuronal soma in the hippocampus, resulting in severe neuronal loss in the PS19 Tau transgenic mice. Moreover, Tmem106b-/- PS19 mice develop significantly increased abnormalities in the neuronal cytoskeleton, autophagy-lysosome activities, as well as glial activation, compared with PS19 and Tmem106b-/- mice. Together, our findings demonstrate that loss of TMEM106B drastically exacerbates Tau pathology and its associated disease phenotypes, and provide new insights into the roles of TMEM106B in neurodegenerative diseases.
    Keywords:  Lysosome; Neurodegeneration; PS19; TMEM106B; Tau
    DOI:  https://doi.org/10.1007/s00401-024-02702-4
  41. Int J Mol Sci. 2024 Mar 09. pii: 3167. [Epub ahead of print]25(6):
    RNA Expression of MMP12 Is Strongly Associated with Inflammatory Bowel Disease and Is Regulated by Metabolic Pathways in RAW 264.7 Macrophages.
    Laura Arosa, Miguel Camba-Gómez, Luis Francisco Lorenzo-Martín, Laura Clavaín, Miguel López, Javier Conde-Aranda.
      Macrophage metalloelastase or matrix metalloproteinase-12 (MMP12) is a macrophage-specific proteolytic enzyme involved in the physiopathology of many inflammatory diseases, including inflammatory bowel disease. Although previously published data suggested that the modulation of MMP12 in macrophages could be a determinant for the development of intestinal inflammation, scarce information is available on the mechanisms underlying the regulation of MMP12 expression in those phagocytes. Therefore, in this study, we aimed to delineate the association of MMP12 with inflammatory bowel disease and the molecular events leading to the transcriptional control of this metalloproteinase. For that, we used publicly available transcriptional data. Also, we worked with the RAW 264.7 macrophage cell line for functional experiments. Our results showed a strong association of MMP12 expression with the severity of inflammatory bowel disease and the response to relevant biological therapies. In vitro assays revealed that the inhibition of mechanistic target of rapamycin complex 1 (mTORC1) and the stimulation of the AMP-activated protein kinase (AMPK) signaling pathway potentiated the expression of Mmp12. Additionally, AMPK and mTOR required a functional downstream glycolytic pathway to fully engage with Mmp12 expression. Finally, the pharmacological inhibition of MMP12 abolished the expression of the proinflammatory cytokine Interleukin-6 (Il6) in macrophages. Overall, our findings provide a better understanding of the mechanistic regulation of MMP12 in macrophages and its relationship with inflammation.
    Keywords:  inflammation; macrophages; metalloprotease; ulcerative colitis
    DOI:  https://doi.org/10.3390/ijms25063167
  42. Genes (Basel). 2024 Mar 04. pii: 332. [Epub ahead of print]15(3):
    The Genetics of Tuberous Sclerosis Complex and Related mTORopathies: Current Understanding and Future Directions.
    Alice Man, Matteo Di Scipio, Shan Grewal, Yujin Suk, Elisabetta Trinari, Resham Ejaz, Robyn Whitney.
      The mechanistic target of rapamycin (mTOR) pathway serves as a master regulator of cell growth, proliferation, and survival. Upregulation of the mTOR pathway has been shown to cause malformations of cortical development, medically refractory epilepsies, and neurodevelopmental disorders, collectively described as mTORopathies. Tuberous sclerosis complex (TSC) serves as the prototypical mTORopathy. Characterized by the development of benign tumors in multiple organs, pathogenic variants in TSC1 or TSC2 disrupt the TSC protein complex, a negative regulator of the mTOR pathway. Variants in critical domains of the TSC complex, especially in the catalytic TSC2 subunit, correlate with increased disease severity. Variants in less crucial exons and non-coding regions, as well as those undetectable with conventional testing, may lead to milder phenotypes. Despite the assumption of complete penetrance, expressivity varies within families, and certain variants delay disease onset with milder neurological effects. Understanding these genotype-phenotype correlations is crucial for effective clinical management. Notably, 15% of patients have no mutation identified by conventional genetic testing, with the majority of cases postulated to be caused by somatic TSC1/TSC2 variants which present complex diagnostic challenges. Advancements in genetic testing, prenatal screening, and precision medicine hold promise for changing the diagnostic and treatment paradigm for TSC and related mTORopathies. Herein, we explore the genetic and molecular mechanisms of TSC and other mTORopathies, emphasizing contemporary genetic methods in understanding and diagnosing the condition.
    Keywords:  focal cortical dysplasia; genetic epilepsies; genetic testing; mTORopathies; malformations of cortical development; mosaicism; precision medicine; tuberous sclerosis complex
    DOI:  https://doi.org/10.3390/genes15030332
  43. Dev Biol. 2024 Mar 26. pii: S0012-1606(24)00088-5. [Epub ahead of print]
    Loss of function of phosphatidylserine synthase causes muscle atrophy in Drosophila.
    Sangseob Kim, Hyun Heo, Seung-Hae Kwon, Jae H Park, Gyunghee Lee, Sang-Hak Jeon.
      Maintenance of appropriate muscle mass is crucial for physical activity and metabolism. Aging and various pathological conditions can cause sarcopenia, a condition characterized by muscle mass decline. Although sarcopenia has been actively studied, the mechanisms underlying muscle atrophy are not well understood. Thus, we aimed to investigate the role of Phosphatidylserine synthase (Pss) in muscle development and homeostasis in Drosophila. The results showed that muscle-specific Pss knockdown decreased exercise capacity and produced sarcopenic phenotypes. In addition, it increased the apoptosis rate because of the elevated reactive oxygen species production resulting from mitochondrial dysfunction. Moreover, the autophagy rate increased due to increased FoxO activity caused by reduced Akt activity. Collectively, these findings demonstrate that enhanced apoptosis and autophagy rates resulting from muscle-specific Pss knockdown jointly contribute to sarcopenia development, highlighting the key role of the PSS pathway in muscle health.
    Keywords:  Akt/FoxO; Autophagy; Mitochondria; Muscle atrophy; Phosphatidylserine synthase; Sarcopenia
    DOI:  https://doi.org/10.1016/j.ydbio.2024.03.006
  44. Brain. 2024 Mar 25. pii: awae092. [Epub ahead of print]
    APP antisense oligonucleotides reduce Aβ aggregation and rescue endolysosomal dysfunction in Alzheimer's disease.
    Christy Hung, Emre Fertan, Frederick J Livesey, David Klenerman, Rickie Patani.
      APP gene dosage is strongly associated with Alzheimer's disease (AD) pathogenesis. Genomic duplication of the APP locus leads to autosomal dominant early-onset AD. Individuals with Down syndrome (trisomy of chromosome 21) harbor 3 copies of the APP gene and invariably develop progressive AD with highly characteristic neuropathological features. Restoring expression of APP to the equivalent of that of two gene copies, or lower, is a rational therapeutic strategy, as it would restore physiological levels of neuronal APP protein without the potentially deleterious consequences of inadvertently inducing loss of APP function. Here we find that antisense oligonucleotides (ASOs) targeting APP are an effective approach to reduce APP protein levels and rescue endolysosome and autophagy dysfunction in APP duplication human induced pluripotent stem cell (hiPSC)-derived cortical neurons. Importantly, using ultrasensitive single-aggregate imaging techniques, we show that APP targeting ASOs significantly reduce both intracellular and extracellular Aβ-containing aggregates. Our results highlight the potential of APP ASOs as a therapeutic approach for forms of AD caused by duplication of the APP gene, including monogenic AD and AD related to Down syndrome.
    Keywords:  Endosome; aggregation; amyloid precursor protein; autophagy; iPSCs; lysosome
    DOI:  https://doi.org/10.1093/brain/awae092
  45. J Biol Chem. 2024 Mar 27. pii: S0021-9258(24)01732-0. [Epub ahead of print] 107235
    Deafness-associated tRNAPhe mutation impaired mitochondrial and cellular integrity.
    Xiaowan Chen, Feilong Meng, Chao Chen, Shujuan Li, Zhiqiang Chou, Baicheng Xu, Jun Q Mo, Yufen Guo, Min-Xin Guan.
      Defects in mitochondrial RNA metabolism have been linked to sensorineural deafness that often occurs as a consequence of damaged or deficient inner ear hair cells. In this report, we investigated the molecular mechanism underlying a deafness-associated tRNAPhe 593T>C mutation that changed a highly conserved uracil to cytosine at the position 17 of DHU-loop. The m.593T>C mutation altered tRNAPhe structure and function, including increased melting temperature, resistance to S1 nuclease-mediated digestion and conformational changes. The aberrant tRNA metabolism impaired mitochondrial translation, which was especially pronounced by decreases in levels of ND1, ND5, CYTB, CO1 and CO3 harboring higher numbers of phenylalanine. These alterations resulted in aberrant assembly, instability and reduced activities of respiratory chain enzyme complexes I, III, IV and intact supercomplexes overall. Furthermore, we found that the m.593T>C mutation caused markedly diminished membrane potential, and increased the production of reactive oxygen species in the mutant cell lines carrying the m.593T>C mutation. These mitochondrial dysfunctions led to the mitochondrial dynamic imbalance via increasing fission with abnormal mitochondrial morphology. Excessive fission impaired the process of autophagy including initiation phase, formation and maturation of the autophagosome. In particular, the m.593T>C mutation upregulated the PARKIN-dependent mitophagy pathway. These alterations promoted an intrinsic apoptotic process for the removal of damaged cells. Our findings provide critical insights into the pathophysiology of maternally inherited deafness arising from tRNA mutation-induced defects in mitochondrial and cellular integrity.
    Keywords:  apoptosis; deafness; mitochondrial dynamics; mitochondrial tRNA mutation; mitophagy
    DOI:  https://doi.org/10.1016/j.jbc.2024.107235
  46. Cells. 2024 Mar 07. pii: 473. [Epub ahead of print]13(6):
    The Mitochondrial Connection: The Nek Kinases' New Functional Axis in Mitochondrial Homeostasis.
    Fernanda L Basei, Ivan Rosa E Silva, Pedro R Firmino Dias, Camila C Ferezin, Andressa Peres de Oliveira, Luidy K Issayama, Livia A R Moura, Fernando Riback da Silva, Jörg Kobarg.
      Mitochondria provide energy for all cellular processes, including reactions associated with cell cycle progression, DNA damage repair, and cilia formation. Moreover, mitochondria participate in cell fate decisions between death and survival. Nek family members have already been implicated in DNA damage response, cilia formation, cell death, and cell cycle control. Here, we discuss the role of several Nek family members, namely Nek1, Nek4, Nek5, Nek6, and Nek10, which are not exclusively dedicated to cell cycle-related functions, in controlling mitochondrial functions. Specifically, we review the function of these Neks in mitochondrial respiration and dynamics, mtDNA maintenance, stress response, and cell death. Finally, we discuss the interplay of other cell cycle kinases in mitochondrial function and vice versa. Nek1, Nek5, and Nek6 are connected to the stress response, including ROS control, mtDNA repair, autophagy, and apoptosis. Nek4, in turn, seems to be related to mitochondrial dynamics, while Nek10 is involved with mitochondrial metabolism. Here, we propose that the participation of Neks in mitochondrial roles is a new functional axis for the Nek family.
    Keywords:  Nek kinase family functions; cell cycle; cellular signaling; mitochondrial homeostasis
    DOI:  https://doi.org/10.3390/cells13060473
  47. CNS Neurosci Ther. 2024 Mar;30(3): e14691
    RACK1 promotes autophagy via the PERK signaling pathway to protect against traumatic brain injury in rats.
    Haibo Ni, Xugang Kan, Qin Rui, Yang Zhang, Weiwei Zhai, Baole Zhang, Zhengquan Yu.
       AIMS: Neuronal cell death is a primary factor that determines the outcome after traumatic brain injury (TBI). We previously revealed the importance of receptor for activated C kinase (RACK1), a multifunctional scaffold protein, in maintaining neuronal survival after TBI, but the specific mechanism remains unclear. The aim of this study was to explore the mechanism underlying RACK1-mediated neuroprotection in TBI.
    METHODS: TBI model was established using controlled cortical impact injury in Sprague-Dawley rats. Genetic intervention and pharmacological inhibition of RACK1 and PERK-autophagy signaling were administrated by intracerebroventricular injection. Western blotting, coimmunoprecipitation, transmission electron microscopy, real-time PCR, immunofluorescence, TUNEL staining, Nissl staining, neurobehavioral tests, and contusion volume assessment were performed.
    RESULTS: Endogenous RACK1 was upregulated and correlated with autophagy induction after TBI. RACK1 knockdown markedly inhibited TBI-induced autophagy, whereas RACK1 overexpression exerted the opposite effects. Moreover, RACK1 overexpression ameliorated neuronal apoptosis, neurological deficits, and cortical tissue loss after TBI, and these effects were abrogated by the autophagy inhibitor 3-methyladenine or siRNAs targeting Beclin1 and Atg5. Mechanistically, RACK1 interacted with PERK and activated PERK signaling. Pharmacological and genetic inhibition of the PERK pathway abolished RACK1-induced autophagy after TBI.
    CONCLUSION: Our findings indicate that RACK1 protected against TBI-induced neuronal damage partly through autophagy induction by regulating the PERK signaling pathway.
    Keywords:  PERK; RACK1; autophagy; neuroprotection; traumatic brain injury
    DOI:  https://doi.org/10.1111/cns.14691
  48. FEBS J. 2024 Mar 28.
    Transfer and fates of damaged mitochondria: role in health and disease.
    Hanbing Li, Weiyun Sun, Wenwen Gong, Yubing Han.
      Intercellular communication is pivotal in mediating the transfer of mitochondria from donor to recipient cells. This process orchestrates various biological functions, including tissue repair, cell proliferation, differentiation and cancer invasion. Typically, dysfunctional and depolarized mitochondria are eliminated through intracellular or extracellular pathways. Nevertheless, increasing evidence suggests that intercellular transfer of damaged mitochondria is associated with the pathogenesis of diverse diseases. This review investigates the prevalent triggers of mitochondrial damage and the underlying mechanisms of mitochondrial transfer, and elucidates the role of directional mitochondrial transfer in both physiological and pathological contexts. Additionally, we propose potential previously unknown mechanisms mediating mitochondrial transfer and explore their prospective roles in disease prevention and therapy.
    Keywords:  cell communication; disease; extracellular vesicles; mitochondria; mitochondrial quality control; mitochondrial transfer
    DOI:  https://doi.org/10.1111/febs.17119
  49. Exp Mol Med. 2024 Mar 27.
    Involvement of DJ-1 in the pathogenesis of intervertebral disc degeneration via hexokinase 2-mediated mitophagy.
    Jialiang Lin, Longjie Wang, Yuhao Wu, Qian Xiang, Yongzhao Zhao, Xuanqi Zheng, Shuai Jiang, Zhuoran Sun, Dongwei Fan, Weishi Li.
      Intervertebral disc degeneration (IDD) is an important pathological basis for degenerative spinal diseases and is involved in mitophagy dysfunction. However, the molecular mechanisms underlying mitophagy regulation in IDD remain unclear. This study aimed to clarify the role of DJ-1 in regulating mitophagy during IDD pathogenesis. Here, we showed that the mitochondrial localization of DJ-1 in nucleus pulposus cells (NPCs) first increased and then decreased in response to oxidative stress. Subsequently, loss- and gain-of-function experiments revealed that overexpression of DJ-1 in NPCs inhibited oxidative stress-induced mitochondrial dysfunction and mitochondria-dependent apoptosis, whereas knockdown of DJ-1 had the opposite effect. Mechanistically, mitochondrial translocation of DJ-1 promoted the recruitment of hexokinase 2 (HK2) to damaged mitochondria by activating Akt and subsequently Parkin-dependent mitophagy to inhibit oxidative stress-induced apoptosis in NPCs. However, silencing Parkin, reducing mitochondrial recruitment of HK2, or inhibiting Akt activation suppressed DJ-1-mediated mitophagy. Furthermore, overexpression of DJ-1 ameliorated IDD in rats through HK2-mediated mitophagy. Taken together, these findings indicate that DJ-1 promotes HK2-mediated mitophagy under oxidative stress conditions to inhibit mitochondria-dependent apoptosis in NPCs and could be a therapeutic target for IDD.
    DOI:  https://doi.org/10.1038/s12276-024-01196-0
  50. Int J Hematol. 2024 Mar 26.
    Rapamycin increases leukemia cell sensitivity to chemotherapy by regulating mTORC1 pathway-mediated apoptosis and autophagy.
    Jing Xu, Siwen Zong, Tianle Sheng, Jifu Zheng, Qiong Wu, Qingming Wang, Aiping Tang, Yuan Song, Yan Fei, Zhenjiang Li.
      This study investigated the effect of rapamycin alone and in combination with chemotherapy (doxorubicin and cytarabine) on AML. Human acute monocytic leukemia cell line SHI-1 and NPG AML model mice created by intravenous injection of SHI-1 cell were treated with rapamycin, chemotherapy, or rapamycin plus chemotherapy. Analysis by cell counting kit-8, western blot, flow cytometry, and immunohistochemistry was performed, and results suggested that both rapamycin and chemotherapy inhibited proliferation of SHI-1 cells both in vitro and in vivo, suppressed neoplasm growth in vivo, and promoted survival of NPG AML mice. The antitumor effect of rapamycin plus chemotherapy was better than that of rapamycin alone and chemotherapy alone. In addition, western blot results demonstrated that rapamycin inhibited the phosphorylation of mTOR downstream targets 4EBP1 and S6K1 in SHI-1 cells, and increased the pro-apoptosis-related protein Bax and autophagy-associated proteins Beclin-1, LC3B-II, and ATG5 while reducing the anti-apoptosis-related protein Bcl-2. In conclusion, the results of this study indicate that rapamycin acts synergistically with doxorubicin and cytarabine in AML treatment, and its underlying mechanism might be associated with mTORC1 pathway-mediated apoptosis and autophagy.
    Keywords:  4EBP1; Apoptosis; Leukemia; Rapamycin; S6K1; mTOR
    DOI:  https://doi.org/10.1007/s12185-024-03732-0
  51. Toxicol In Vitro. 2024 Mar 21. pii: S0887-2333(24)00039-0. [Epub ahead of print]97 105809
    DMC triggers MDA-MB-231 cells apoptosis via inhibiting protective autophagy and PI3K/AKT/mTOR pathway by enhancing ROS level.
    Yu Jiang, Sunjie Xu, Miaomiao Guo, Zhi Lu, Xing Wei, Faliang An, Xiujuan Xin.
      DMC, a kind of compound derived from the dry flower buds of Cleistocalyx operculatus, has been shown to inhibit the growth of various cancer cells, but research on triple-negative breast cancer cells remains scarce. To explore this issue, MDA-MB-231 cells were selected, and the results showed that DMC has strong proliferation inhibit effects on this kind of cells. The inhibit rate of 30 μM DMC incubated for 24 h was 56.25%, and 40.6% cells were arrested under the G2/M phase. The levels of pro-apoptosis protein Bax and active caspase-3, cleaved PARP and cell cycle related proteins, such as p21 and p27 increased, but apoptosis regulators, like Bcl-2, Cdc 2, Cyclin B1, and LC3 II decreased dramatically. In addition, DMC induced the accumulation of autophagosomes and autophagic substrates, and the combination of DMC with CQ promoted apoptosis of MDA-MB-231 cells, which suggested that DMC induced apoptosis partly by blocking autophagy flow. Moreover, the phosphorylation levels of phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT), and its mechanistic target of rapamycin kinase (mTOR) were also decreased after 30 μM DMC incubating for 24 h. The proteins play a critical role in cell proliferation, apoptosis, and autophagy modulation. The inhibition of autophagy flow and PI3K/AKT/mTOR pathway could be reversed after being treated with ROS scavenger NAC. Altogether, the results of the present study suggest that DMC effectively induces apoptosis and growth inhibition in MDA-MB-231 cells through blocking autophagy flow and regulating the PI3K/AKT/mTOR pathway by increasing ROS level.
    Keywords:  Apoptosis; DMC; MDA-MB-231 cells; PI3K-AKT-mTOR pathway
    DOI:  https://doi.org/10.1016/j.tiv.2024.105809
  52. Biol Cell. 2024 Mar 27. e2300067
    Deletion of Dictyostelium tpc2 gene forms multi-tipped structures, regulates autophagy and cell-type patterning.
    Madhubala Rathore, Ashima Thakur, Shweta Saran.
       BACKGROUND INFORMATION: Two pore channels (TPCs) are voltage-gated ion channel superfamily members that release Ca2+ from acidic intracellular stores and are ubiquitously present in both animals and plants. Starvation initiates multicellular development in Dictyostelium discoideum. Increased intracellular calcium levels bias Dictyostelium cells towards the stalk pathway and thus we decided to analyze the role of TPC2 in development, differentiation, and autophagy.
    RESULTS: We showed TPC2 protein localizes in lysosome-like acidic vesicles and the in situ data showed stalk cell biasness. Deletion of tpc2 showed defective and delayed development with formation of multi-tipped structures attached to a common base, while tpc2OE cells showed faster development with numerous small-sized aggregates and wiry fruiting bodies. The tpc2OE cells showed higher intracellular cAMP levels as compared to the tpc2- cells while pinocytosis was found to be higher in the tpc2- cells. Also, TPC2 regulates cell-substrate adhesion and cellular morphology. Under nutrient starvation, deletion of tpc2 reduced autophagic flux as compared to Ax2. During chimera formation, tpc2- cells showed a bias towards the prestalk/stalk region while tpc2OE cells showed a bias towards the prespore/spore region. tpc2 deficient strain exhibits aberrant cell-type patterning and loss of distinct boundary between the prestalk/prespore regions.
    CONCLUSION: TPC2 is required for effective development and differentiation in Dictyostelium and supports autophagic cell death and cell-type patterning.
    SIGNIFICANCE: Decreased calcium due to deletion of tpc2 inhibit autophagic flux.
    Keywords:  Dictyostelium; autophagic flux; cell‐fate choice; cell‐type patterning; development; two‐pore channel 2 (TPC2)
    DOI:  https://doi.org/10.1111/boc.202300067
  53. Nat Commun. 2024 Mar 26. 15(1): 2367
    The level of protein in the maternal murine diet modulates the facial appearance of the offspring via mTORC1 signaling.
    Meng Xie, Markéta Kaiser, Yaakov Gershtein, Daniela Schnyder, Ruslan Deviatiiarov, Guzel Gazizova, Elena Shagimardanova, Tomáš Zikmund, Greet Kerckhofs, Evgeny Ivashkin, Dominyka Batkovskyte, Phillip T Newton, Olov Andersson, Kaj Fried, Oleg Gusev, Hugo Zeberg, Jozef Kaiser, Igor Adameyko, Andrei S Chagin.
      The development of craniofacial skeletal structures is fascinatingly complex and elucidation of the underlying mechanisms will not only provide novel scientific insights, but also help develop more effective clinical approaches to the treatment and/or prevention of the numerous congenital craniofacial malformations. To this end, we performed a genome-wide analysis of RNA transcription from non-coding regulatory elements by CAGE-sequencing of the facial mesenchyme of human embryos and cross-checked the active enhancers thus identified against genes, identified by GWAS for the normal range human facial appearance. Among the identified active cis-enhancers, several belonged to the components of the PI3/AKT/mTORC1/autophagy pathway. To assess the functional role of this pathway, we manipulated it both genetically and pharmacologically in mice and zebrafish. These experiments revealed that mTORC1 signaling modulates craniofacial shaping at the stage of skeletal mesenchymal condensations, with subsequent fine-tuning during clonal intercalation. This ability of mTORC1 pathway to modulate facial shaping, along with its evolutionary conservation and ability to sense external stimuli, in particular dietary amino acids, indicate that the mTORC1 pathway may play a role in facial phenotypic plasticity. Indeed, the level of protein in the diet of pregnant female mice influenced the activity of mTORC1 in fetal craniofacial structures and altered the size of skeletogenic clones, thus exerting an impact on the local geometry and craniofacial shaping. Overall, our findings indicate that the mTORC1 signaling pathway is involved in the effect of environmental conditions on the shaping of craniofacial structures.
    DOI:  https://doi.org/10.1038/s41467-024-46030-3
  54. Autophagy. 2024 Mar 24. 1-18
    Impaired neuronal macroautophagy in the prelimbic cortex contributes to comorbid anxiety-like behaviors in rats with chronic neuropathic pain.
    Su Fu, Haojie Sun, Jiaxin Wang, Shuaixin Gao, Liu Zhu, Kun Cui, Shimeng Liu, Xuetao Qi, Rui Guan, Xiaocen Fan, Qingying Liu, Wen Chen, Li Su, Shuang Cui, Feifei Liao, Fengyu Liu, Catherine C L Wong, Ming Yi, You Wan.
      A large proportion of patients with chronic pain experience co-morbid anxiety. The medial prefrontal cortex (mPFC) is proposed to underlie this comorbidity, but the molecular and neuronal mechanisms are not fully understood. Here, we reported that impaired neuronal macroautophagy in the prelimbic cortical (PrL) subregion of the mPFC paralleled the occurrence of anxiety-like behaviors in rats with chronic spared nerve injury (SNI). Intriguingly, such macroautophagy impairment was mainly observed in a FOS/c-Fos+ neuronal subpopulation in the PrL. Chemogenetic inactivation of this comorbid anxiety-related neuronal ensemble relieved pain-induced anxiety-like behaviors. Rescuing macroautophagy impairment in this neuronal ensemble relieved chronic pain-associated anxiety and mechanical allodynia and restored synaptic homeostasis at the molecular level. By contrast, artificial disruption of macroautophagy induced early-onset co-morbid anxiety in neuropathic rats, but not general anxiety in normal rats. Taken together, our work identifies causal linkage between PrL neuronal macroautophagy dysfunction and comorbid anxiety in neuropathic pain and provides novel insights into the role of PrL by differentiating its contribution in pain-induced comorbid anxiety from its modulation over general anxiety-like behaviors.Abbreviation: AAV: adeno-associated viruses; ACC: anterior cingulate cortex; ATG5: autophagy related 5; ATG7: autophagy related 7; ATG12: autophagy related 12; CAMK2/CaMKII: calcium/calmodulin-dependent protein kinase II; CNO: clozapine-N-oxide; CQ: chloroquine; DIA: data independent acquisition; DIO: double floxed inverse orf; DLG4/PSD-95: discs large MAGUK scaffold protein 4; Dox: doxycycline; GABA: γ-aminobutyric acid; GFP: green fluorescent protein; GO: gene ontology; Gi: inhibitory guanine nucleotide-binding proteins; HsCHRM4/M4D: human cholinergic receptor muscarinic 4; HsSYN: human synapsin; KEGG: Kyoto encyclopedia of genes and genomes; LAMP1: lysosomal-associated membrane protein 1; LC3-II: PE conjugated microtubule-associated protein 1 light chain3; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; mPFC: medial prefrontal cortex; P2A: 2A self-cleaving peptide; PPI: protein-protein interaction networks; PrL: prelimbic cortex; RBFOX3/NeuN: RNA binding protein, fox-1 homolog (C. elegans) 3; rtTA: reverse tetracycline-transactivator; SDS-PAGE: sodium dodecylsulfate-polyacrylamide gel electrophoresis; SHANK3: SH3 and multiple ankyrin repeat domains 3; SLC1A1/EAAC1: solute carrier family 1 (neuronal/epithelial high affinity glutamate transporter, systemXag), member 1; SNAP23: synaptosomal-associated protein 23; SNI:spared nerve injury; SQSTM1/p62: sequestosome 1; SYT3: synaptotagmin 3; TRE: tetracycline-responsive element; TRE3G: third-generation tetracycline-responsive element.
    Keywords:  Autophagy; chronic neuropathic pain; comorbid anxiety; neuronal ensemble; prelimbic cortex; synaptic homeostasis
    DOI:  https://doi.org/10.1080/15548627.2024.2330038
  55. Nat Commun. 2024 Mar 28. 15(1): 2465
    Autophagy-enhancing ATG16L1 polymorphism is associated with improved clinical outcome and T-cell immunity in chronic HIV-1 infection.
    Renée R C E Schreurs, Athanasios Koulis, Thijs Booiman, Brigitte Boeser-Nunnink, Alexandra P M Cloherty, Anusca G Rader, Kharishma S Patel, Neeltje A Kootstra, Carla M S Ribeiro.
      Chronic HIV-1 infection is characterized by T-cell dysregulation that is partly restored by antiretroviral therapy. Autophagy is a critical regulator of T-cell function. Here, we demonstrate a protective role for autophagy in HIV-1 disease pathogenesis. Targeted analysis of genetic variation in core autophagy gene ATG16L1 reveals the previously unidentified rs6861 polymorphism, which correlates functionally with enhanced autophagy and clinically with improved survival of untreated HIV-1-infected individuals. T-cells carrying ATG16L1 rs6861(TT) genotype display improved antiviral immunity, evidenced by increased proliferation, revamped immune responsiveness, and suppressed exhaustion/immunosenescence features. In-depth flow-cytometric and transcriptional profiling reveal T-helper-cell-signatures unique to rs6861(TT) individuals with enriched regulation of pro-inflammatory networks and skewing towards immunoregulatory phenotype. Therapeutic enhancement of autophagy recapitulates the rs6861(TT)-associated T-cell traits in non-carriers. These data underscore the in vivo relevance of autophagy for longer-lasting T-cell-mediated HIV-1 control, with implications towards development of host-directed antivirals targeting autophagy to restore immune function in chronic HIV-1 infection.
    DOI:  https://doi.org/10.1038/s41467-024-46606-z
  56. Biomolecules. 2024 Mar 09. pii: 326. [Epub ahead of print]14(3):
    The Development of LAT1 Efflux Agonists as Mechanistic Probes of Cellular Amino Acid Stress.
    Vandana Sekhar, Houssine Ikhlef, Alexandra Bunea, Viet S Nguyen, Johan Joo, Mukund P Tantak, Holly Moots, Otto Phanstiel.
      Amino acid restriction induces cellular stress and cells often respond via the induction of autophagy. Autophagy or 'self-eating' enables the recycling of proteins and provides the essential amino acids needed for cell survival. Of the naturally occurring amino acids, methionine restriction has pleiotropic effects on cells because methionine also contributes to the intracellular methyl pools required for epigenetic controls as well as polyamine biosynthesis. In this report, we describe the chemical synthesis of four diastereomers of a methionine depletion agent and demonstrate how controlled methionine efflux from cells significantly reduces intracellular methionine, S-adenosylmethionine (SAM), S-adenosyl homocysteine (SAH), and polyamine levels. We also demonstrate that human pancreatic cancer cells respond via a lipid signaling pathway to induce autophagy. The methionine depletion agent causes the large amino acid transporter 1 (LAT1) to preferentially work in reverse and export the cell's methionine (and leucine) stores. The four diastereomers of the lead methionine/leucine depletion agent were synthesized and evaluated for their ability to (a) efflux 3H-leucine from cells, (b) dock to LAT1 in silico, (c) modulate intracellular SAM, SAH, and phosphatidylethanolamine (PE) pools, and (d) induce the formation of the autophagy-associated LC3-II marker. The ability to modulate the intracellular concentration of methionine regardless of exogenous methionine supply provides new molecular tools to better understand cancer response pathways. This information can then be used to design improved therapeutics that target downstream methionine-dependent processes like polyamines.
    Keywords:  S-adenosylmethionine (SAM); autophagy; lipid signaling; methionine efflux
    DOI:  https://doi.org/10.3390/biom14030326
  57. Front Cardiovasc Med. 2024 ;11 1364604
    Recent advances of myotubularin-related (MTMR) protein family in cardiovascular diseases.
    Jia Wang, Wei Guo, Qiang Wang, Yongjian Yang, Xiongshan Sun.
      Belonging to a lipid phosphatase family containing 16 members, myotubularin-related proteins (MTMRs) are widely expressed in a variety of tissues and organs. MTMRs preferentially hydrolyzes phosphatidylinositol 3-monophosphate and phosphatidylinositol (3,5) bis-phosphate to generate phosphatidylinositol and phosphatidylinositol 5-monophosphate, respectively. These phosphoinositides (PIPs) promote membrane degradation during autophagosome-lysosomal fusion and are also involved in various regulatory signal transduction. Based on the ability of modulating the levels of these PIPs, MTMRs exert physiological functions such as vesicle trafficking, cell proliferation, differentiation, necrosis, cytoskeleton, and cell migration. It has recently been found that MTMRs are also involved in the occurrence and development of several cardiovascular diseases, including cardiomyocyte hypertrophy, proliferation of vascular smooth muscle cell, LQT1, aortic aneurysm, etc. This review summarizes the functions of MTMRs and highlights their pathophysiological roles in cardiovascular diseases.
    Keywords:  MTMR; PI3K/AKT; autophagy; cardiovascular diseases; phosphoinositide
    DOI:  https://doi.org/10.3389/fcvm.2024.1364604
  58. Nature. 2024 Mar 27.
    The race to uncover fission factors for lysosomal organelles heats up.
    Shilpa Gopan, Thomas J Pucadyil.
      
    Keywords:  Cell biology
    DOI:  https://doi.org/10.1038/d41586-024-00851-w
  59. Food Funct. 2024 Mar 26.
    Se-methylselenocysteine ameliorates mitochondrial function by targeting both mitophagy and autophagy in the mouse model of Alzheimer's disease.
    Yongli Xie, Xiaoshan Ke, Zhencong Ye, Xuexia Li, Zetao Chen, Jiantao Liu, Ziyi Wu, Qiong Liu, Xiubo Du.
      Background: Alzheimer's disease (AD) exerts tremendous pressure on families and society due to its unknown etiology and lack of effective treatment options. Our previous study had shown that Se-methylselenocysteine (SMC) improved the cognition and synaptic plasticity of triple-transgenic AD (3 × Tg-AD) mice and alleviated the related pathological indicators. We are dedicated to investigating the therapeutic effects and molecular mechanisms of SMC on mitochondrial function in 3 × Tg-AD mice. Methods: Transmission electron microscopy (TEM), western blotting (WB), mitochondrial membrane potential (ΔΨm), mitochondrial swelling test, and mitochondrial oxygen consumption test were used to evaluate the mitochondrial morphology and function. Mitophagy flux and autophagy flux were assessed with immunofluorescence, TEM and WB. The Morris water maze test was applied to detect the behavioral ability of mice. Results: The destroyed mitochondrial morphology and function were repaired by SMC through ameliorating mitochondrial energy metabolism, mitochondrial biogenesis and mitochondrial fusion/fission balance in 3 × Tg-AD mice. In addition, SMC ameliorated mitochondria by activating mitophagy flux via the BNIP3/NIX pathway and triggering autophagy flux by suppressing the Ras/Raf/MEK/ERK/mTOR pathway. SMC remarkably increased the cognitive ability of AD mice. Conclusions: This research indicated that SMC might exert its therapeutic effect by protecting mitochondria in 3 × Tg-AD mice.
    DOI:  https://doi.org/10.1039/d4fo00520a
  60. Nat Commun. 2024 Mar 22. 15(1): 2598
    Rab4A-directed endosome traffic shapes pro-inflammatory mitochondrial metabolism in T cells via mitophagy, CD98 expression, and kynurenine-sensitive mTOR activation.
    Nick Huang, Thomas Winans, Brandon Wyman, Zachary Oaks, Tamas Faludi, Gourav Choudhary, Zhi-Wei Lai, Joshua Lewis, Miguel Beckford, Manuel Duarte, Daniel Krakko, Akshay Patel, Joy Park, Tiffany Caza, Mahsa Sadeghzadeh, Laurence Morel, Mark Haas, Frank Middleton, Katalin Banki, Andras Perl.
      Activation of the mechanistic target of rapamycin (mTOR) is a key metabolic checkpoint of pro-inflammatory T-cell development that contributes to the pathogenesis of autoimmune diseases, such as systemic lupus erythematosus (SLE), however, the underlying mechanisms remain poorly understood. Here, we identify a functional role for Rab4A-directed endosome traffic in CD98 receptor recycling, mTOR activation, and accumulation of mitochondria that connect metabolic pathways with immune cell lineage development and lupus pathogenesis. Based on integrated analyses of gene expression, receptor traffic, and stable isotope tracing of metabolic pathways, constitutively active Rab4AQ72L exerts cell type-specific control over metabolic networks, dominantly impacting CD98-dependent kynurenine production, mTOR activation, mitochondrial electron transport and flux through the tricarboxylic acid cycle and thus expands CD4+ and CD3+CD4-CD8- double-negative T cells over CD8+ T cells, enhancing B cell activation, plasma cell development, antinuclear and antiphospholipid autoantibody production, and glomerulonephritis in lupus-prone mice. Rab4A deletion in T cells and pharmacological mTOR blockade restrain CD98 expression, mitochondrial metabolism and lineage skewing and attenuate glomerulonephritis. This study identifies Rab4A-directed endosome traffic as a multilevel regulator of T cell lineage specification during lupus pathogenesis.
    DOI:  https://doi.org/10.1038/s41467-024-46441-2
  61. Genes (Basel). 2024 Mar 04. pii: 334. [Epub ahead of print]15(3):
    FOXO3/Rab7-Mediated Lipophagy and Its Role in Zn-Induced Lipid Metabolism in Yellow Catfish (Pelteobagrus fulvidraco).
    Fei Xiao, Chuan Chen, Wuxiao Zhang, Jiawei Wang, Kun Wu.
      Lipophagy is a selective autophagy that regulates lipid metabolism and reduces hepatic lipid deposition. However, the underlying mechanism has not been understood in fish. In this study, we used micronutrient zinc (Zn) as a regulator of autophagy and lipid metabolism and found that Ras-related protein 7 (rab7) was involved in Zn-induced lipophagy in hepatocytes of yellow catfish Pelteobagrus pelteobagrus. We then characterized the rab7 promoter and identified binding sites for a series of transcription factors, including Forkhead box O3 (FOXO3). Site mutation experiments showed that the -1358/-1369 bp FOXO3 binding site was responsible for Zn-induced transcriptional activation of rab7. Further studies showed that inhibition of rab7 significantly inhibited Zn-induced lipid degradation by lipophagy. Moreover, rab7 inhibitor also mitigated the Zn-induced increase of cpt1α and acadm expression. Our results suggested that Zn exerts its lipid-lowering effect partly through rab7-mediated lipophagy and FA β-oxidation in hepatocytes. Overall, our findings provide novel insights into the FOXO3/rab7 axis in lipophagy regulation and enhance the understanding of lipid metabolism by micronutrient Zn, which may help to reduce excessive lipid accumulation in fish.
    Keywords:  FOXO3; Zn; lipid metabolism; lipophagy; promoter analysis; rab7
    DOI:  https://doi.org/10.3390/genes15030334
  62. Int J Mol Sci. 2024 Mar 13. pii: 3251. [Epub ahead of print]25(6):
    Trimetazidine Improves Mitochondrial Dysfunction in SOD1G93A Cellular Models of Amyotrophic Lateral Sclerosis through Autophagy Activation.
    Illari Salvatori, Valentina Nesci, Alida Spalloni, Veronica Marabitti, Maurizio Muzzi, Henri Zenuni, Silvia Scaricamazza, Marco Rosina, Gianmarco Fenili, Mariangela Goglia, Laura Boffa, Roberto Massa, Sandra Moreno, Nicola Biagio Mercuri, Francesca Nazio, Patrizia Longone, Alberto Ferri, Cristiana Valle.
      Amyotrophic Lateral Sclerosis (ALS) is considered the prototype of motor neuron disease, characterized by motor neuron loss and muscle waste. A well-established pathogenic hallmark of ALS is mitochondrial failure, leading to bioenergetic deficits. So far, pharmacological interventions for the disease have proven ineffective. Trimetazidine (TMZ) is described as a metabolic modulator acting on different cellular pathways. Its efficacy in enhancing muscular and cardiovascular performance has been widely described, although its molecular target remains elusive. We addressed the molecular mechanisms underlying TMZ action on neuronal experimental paradigms. To this aim, we treated murine SOD1G93A-model-derived primary cultures of cortical and spinal enriched motor neurons, as well as a murine motor-neuron-like cell line overexpressing SOD1G93A, with TMZ. We first characterized the bioenergetic profile of the cell cultures, demonstrating significant mitochondrial dysfunction that is reversed by acute TMZ treatments. We then investigated the effect of TMZ in promoting autophagy processes and its impact on mitochondrial morphology. Finally, we demonstrated the effectiveness of TMZ in terms of the mitochondrial functionality of ALS-rpatient-derived peripheral blood mononuclear cells (PBMCs). In summary, our results emphasize the concept that targeting mitochondrial dysfunction may represent an effective therapeutic strategy for ALS. The findings demonstrate that TMZ enhances mitochondrial performance in motor neuron cells by activating autophagy processes, particularly mitophagy. Although further investigations are needed to elucidate the precise molecular pathways involved, these results hold critical implications for the development of more effective and specific derivatives of TMZ for ALS treatment.
    Keywords:  Amyotrophic Lateral Sclerosis; SOD1G93A; Trimetazidine; autophagy; mitochondria; spinal and cortical primary cultures
    DOI:  https://doi.org/10.3390/ijms25063251
  63. Life (Basel). 2024 Feb 28. pii: 316. [Epub ahead of print]14(3):
    Unraveling the Impact of Dab1 Gene Silencing on the Expression of Autophagy Markers in Lung Development.
    Azer Rizikalo, Mirko Maglica, Nela Kelam, Ilija Perutina, Marin Ogorevc, Anita Racetin, Natalija Filipović, Yu Katsuyama, Zdenka Zovko, Josip Mišković, Katarina Vukojević.
      The purpose of this study was to evaluate the effects of Dab1 gene silencing on the immunoexpression of light chain 3 beta (Lc3b), glucose regulating protein 78 (Grp78), heat shock cognate 71 (Hsc70), mammalian target of rapamycin (mTOR) and lysosomal-associated membrane protein 2A (Lamp2a) in the lung tissue of developing yotari (Dab1-/-) and wild-type (wt) mice. The lung epithelium and mesenchyme of the embryos at gestational days E13.5 and E15.5 were examined using immunofluorescence and semi-quantitative methods. In the pulmonary mesenchyme and epithelium, Grp78 and Lc3b of moderate fluorescence reactivity was demonstrated in wt mice for both evaluated time points, while yotari mice exhibited only epithelial reactivity for the same markers. Mild punctate expression of Hsc70 was observed for both genotypes. A significant difference was present when analyzing mTOR expression, where wt mice showed strong perinuclear staining in the epithelium. According to our data, Dab1 gene silencing may result in autophagy abnormalities, which could then cause respiratory system pathologies via defective lung cell degradation by lysosome-dependent cell elimination.
    Keywords:  Grp78; Hsc70; Lamp2a; Lc3b; autophagy; lung injury; mTOR; yotari
    DOI:  https://doi.org/10.3390/life14030316
  64. Nat Commun. 2024 Mar 25. 15(1): 2635
    SKA2 regulated hyperactive secretory autophagy drives neuroinflammation-induced neurodegeneration.
    Jakob Hartmann, Thomas Bajaj, Joy Otten, Claudia Klengel, Tim Ebert, Anne-Kathrin Gellner, Ellen Junglas, Kathrin Hafner, Elmira A Anderzhanova, Fiona Tang, Galen Missig, Lindsay Rexrode, Daniel T Trussell, Katelyn X Li, Max L Pöhlmann, Sarah Mackert, Thomas M Geiger, Daniel E Heinz, Roy Lardenoije, Nina Dedic, Kenneth M McCullough, Tomasz Próchnicki, Thomas Rhomberg, Silvia Martinelli, Antony Payton, Andrew C Robinson, Valentin Stein, Eicke Latz, William A Carlezon, Felix Hausch, Mathias V Schmidt, Chris Murgatroyd, Sabina Berretta, Torsten Klengel, Harry Pantazopoulos, Kerry J Ressler, Nils C Gassen.
      High levels of proinflammatory cytokines induce neurotoxicity and catalyze inflammation-driven neurodegeneration, but the specific release mechanisms from microglia remain elusive. Here we show that secretory autophagy (SA), a non-lytic modality of autophagy for secretion of vesicular cargo, regulates neuroinflammation-mediated neurodegeneration via SKA2 and FKBP5 signaling. SKA2 inhibits SA-dependent IL-1β release by counteracting FKBP5 function. Hippocampal Ska2 knockdown in male mice hyperactivates SA resulting in neuroinflammation, subsequent neurodegeneration and complete hippocampal atrophy within six weeks. The hyperactivation of SA increases IL-1β release, contributing to an inflammatory feed-forward vicious cycle including NLRP3-inflammasome activation and Gasdermin D-mediated neurotoxicity, which ultimately drives neurodegeneration. Results from protein expression and co-immunoprecipitation analyses of male and female postmortem human brains demonstrate that SA is hyperactivated in Alzheimer's disease. Overall, our findings suggest that SKA2-regulated, hyperactive SA facilitates neuroinflammation and is linked to Alzheimer's disease, providing mechanistic insight into the biology of neuroinflammation.
    DOI:  https://doi.org/10.1038/s41467-024-46953-x
  65. Biochim Biophys Acta Mol Cell Res. 2024 Mar 22. pii: S0167-4889(24)00055-7. [Epub ahead of print]1871(4): 119712
    DDIT3/CHOP promotes LPS/ATP-induced pyroptosis in osteoblasts via mitophagy inhibition.
    Zhipeng Dong, Beining Yang, Meie Jia, Chang Yang, Shuo Wang, Hailin Mu, Jiawei Wang.
      Inflammatory environments can trigger endoplasmic reticulum (ER) stress and lead to pyroptosis in various tissues and cells, including liver, brain, and immune cells. As a key factor of ER stress, DNA damage-inducible transcript 3 (DDIT3)/CCAAT/enhancer-binding protein (C/EBP) homologous protein (CHOP) is upregulated in osteoblasts during inflammatory stimulation. DDIT3/CHOP may therefore regulate osteoblast pyroptosis in inflammatory conditions. During this investigation, we found that lipopolysaccharides (LPS)/adenosine 5'-triphosphate (ATP) stimulation in vitro induced osteoblasts to undergo pyroptosis, and the expression of DDIT3/CHOP was increased during this process. The overexpression of DDIT3/CHOP further promoted osteoblast pyroptosis as evidenced by the increased expression of the inflammasome NLR family pyrin domain containing 3 (NLRP3) and ratios of caspase-1 p20/caspase-1 and cleaved gasdermin D (GSDMD)/GSDMD. To explore the specific mechanism of this effect, we found through fluorescence imaging and Western blot analysis that LPS/ATP stimulation promoted PTEN-induced kinase 1 (PINK1)/E3 ubiquitin-protein ligase parkin (Parkin)-mediated mitophagy in osteoblasts, and this alteration was suppressed by the DDIT3/CHOP overexpression, resulting in increased ratio of pyroptosis compared with the control groups. The impact of DDIT3/CHOP on pyroptosis in osteoblasts was reversed by the application of carbonyl cyanide 3-chlorophenylhydrazone (CCCP), a specific mitophagy agonist. Therefore, our data demonstrated that DDIT3/CHOP promotes osteoblast pyroptosis by inhibiting PINK1/Parkin-mediated mitophagy in an inflammatory environment.
    Keywords:  DDIT3/CHOP; Mitophagy; Osteoblast; Pyroptosis
    DOI:  https://doi.org/10.1016/j.bbamcr.2024.119712
  66. Mol Metab. 2024 Mar 23. pii: S2212-8778(24)00052-8. [Epub ahead of print] 101921
    Salubrinal promotes phospho-eIF2α-dependent activation of UPR leading to autophagy-mediated attenuation of iron-induced insulin resistance.
    Khang Nguyen, Jialing Tang, Sungji Cho, Fan Ying, Hye Kyoung Sung, Kostas Pantopoulos, Gary Sweeney.
      Identification of new mechanisms mediating insulin sensitivity is important to allow validation of corresponding therapeutic targets. In this study, we first used a cellular model of skeletal muscle cell iron overload and found endoplasmic reticulum (ER) stress and insulin resistance occurred after iron treatment. Insulin sensitivity was assessed using cells engineered to express an Akt biosensor, based on nuclear FoxO localization, as well as western blotting for insulin signaling proteins. Use of salubrinal to elevate eIF2α phosphorylation and promote the unfolded protein response (UPR) attenuated iron-induced insulin resistance. Salubrinal induced autophagy flux and its beneficial effects on insulin sensitivity were not observed in autophagy-deficient cells generated by overexpressing a dominant-negative Atg5 mutant or via knockout of ATG7. This indicated the beneficial effect of salubrinal-induced UPR activation was autophagy-dependent. We translated these observations to an animal model of systemic iron overload-induced skeletal muscle insulin resistance where administration of salubrinal as pretreatment promoted eIF2α phosphorylation, enhanced autophagic flux in skeletal muscle and improved insulin responsiveness. Together, our results show that salubrinal elicited an eIF2α-autophagy axis leading to improved skeletal muscle insulin sensitivity both in vitro and in mice.
    DOI:  https://doi.org/10.1016/j.molmet.2024.101921
  67. Genes (Basel). 2024 Feb 25. pii: 290. [Epub ahead of print]15(3):
    Drug Repurposing and Lysosomal Storage Disorders: A Trick to Treat.
    Bruno Hay Mele, Federica Rossetti, Maria Vittoria Cubellis, Maria Monticelli, Giuseppina Andreotti.
      Rare diseases, or orphan diseases, are defined as diseases affecting a small number of people compared to the general population. Among these, we find lysosomal storage disorders (LSDs), a cluster of rare metabolic diseases characterized by enzyme mutations causing abnormal glycolipid storage. Drug repositioning involves repurposing existing approved drugs for new therapeutic applications, offering advantages in cost, time savings, and a lower risk of failure. We present a comprehensive analysis of existing drugs, their repurposing potential, and their clinical implications in the context of LSDs, highlighting the necessity of mutation-specific approaches. Our review systematically explores the landscape of drug repositioning as a means to enhance LSDs therapies. The findings advocate for the strategic repositioning of drugs, accentuating its role in expediting the discovery of effective treatments. We conclude that drug repurposing represents a viable pathway for accelerating therapeutic discovery for LSDs, emphasizing the need for the careful evaluation of drug efficacy and toxicity in disease-specific contexts.
    Keywords:  drug repositioning; drug repurposing; lysosomal enzyme disorder; lysosomal storage disease; lysosomal storage disorder
    DOI:  https://doi.org/10.3390/genes15030290
  68. Commun Biol. 2024 Mar 29. 7(1): 382
    Insights on E1-like enzyme ATG7: functional regulation and relationships with aging-related diseases.
    Jingwei Liu, Yutong Xiao, Liangzi Cao, Songming Lu, Siyi Zhang, Ruohan Yang, Yubang Wang, Naijin Zhang, Yang Yu, Xiwen Wang, Wendong Guo, Zhuo Wang, Hongde Xu, Chengzhong Xing, Xiaoyu Song, Liu Cao.
      Autophagy is a dynamic self-renovation biological process that maintains cell homeostasis and is responsible for the quality control of proteins, organelles, and energy metabolism. The E1-like ubiquitin-activating enzyme autophagy-related gene 7 (ATG7) is a critical factor that initiates classic autophagy reactions by promoting the formation and extension of autophagosome membranes. Recent studies have identified the key functions of ATG7 in regulating the cell cycle, apoptosis, and metabolism associated with the occurrence and development of multiple diseases. This review summarizes how ATG7 is precisely programmed by genetic, transcriptional, and epigenetic modifications in cells and the relationship between ATG7 and aging-related diseases.
    DOI:  https://doi.org/10.1038/s42003-024-06080-1
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