Autophagy最新文献

{"title":"Were the autophagosome-lysosome/vacuole fusion models illustrated correctly in the literature?","authors":"Yongheng Liang","doi":"10.1080/15548627.2024.2405954","DOIUrl":"10.1080/15548627.2024.2405954","url":null,"abstract":"<p><p>Exploration of autophagy in different species has become a hotspot in cell biology in the past decades. Macroautophagy (hereafter, autophagy) is the most widely studied type. One of the hallmarks of autophagy is the fusion of the outer membrane (OM) of a closed double-membrane mature autophagosome (AP) with the lysosomal/vacuolar single membrane. Most researchers in the autophagy field agree upon this description. However, AP-lysosome/vacuole fusion models that do not follow this description frequently appear in the literature, even published in some prestigious journals until now. Some of the misrepresented models are from autophagy laboratories with brilliant publication records. These flaws should be addressed as a public announcement in the autophagy field to avoid spreading misinformation. The editors and reviewers are the guardians to ensure correct models.<b>Abbreviations</b>: AP: autophagosome; IM: inner membrane; OM: outer membrane.</p>","PeriodicalId":93893,"journal":{"name":"Autophagy","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142309353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Targeted proteomics addresses selectivity and complexity of protein degradation by autophagy.","authors":"Alexandre Leytens, Rocío Benítez-Fernández, Carlos Jiménez-García, Carole Roubaty, Michael Stumpe, Patricia Boya, Jörn Dengjel","doi":"10.1080/15548627.2024.2396792","DOIUrl":"10.1080/15548627.2024.2396792","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Macroautophagy/autophagy is a constitutively active catabolic lysosomal degradation pathway, often found dysregulated in human diseases. It is often considered to act in a cytoprotective manner and is commonly upregulated in cells undergoing stress. Its initiation is regulated at the protein level and does not require &lt;i&gt;de novo&lt;/i&gt; protein synthesis. Historically, autophagy has been regarded as nonselective; however, it is now clear that different stimuli can lead to the selective degradation of cellular components via selective autophagy receptors (SARs). Due to its selective nature and the existence of multiple degradation pathways potentially acting in concert, monitoring of autophagy flux, &lt;i&gt;i.e&lt;/i&gt;. selective autophagy-dependent protein degradation, should address this complexity. Here, we introduce a targeted proteomics approach monitoring abundance changes of 37 autophagy-related proteins covering process-relevant proteins such as the initiation complex and the Atg8-family protein lipidation machinery, as well as most known SARs. We show that proteins involved in autophagosome biogenesis are upregulated and spared from degradation under autophagy-inducing conditions in contrast to SARs, in a cell-line dependent manner. Classical bulk stimuli such as nutrient starvation mainly induce degradation of ubiquitin-dependent soluble SARs and not of ubiquitin-independent, membrane-bound SARs. In contrast, treatment with the iron chelator deferiprone leads to the degradation of ubiquitin-dependent and -independent SARs linked to mitophagy and reticulophagy/ER-phagy. Our approach is automatable and supports large-scale screening assays paving the way to (pre)clinical applications and monitoring of specific autophagy flux.&lt;b&gt;Abbreviation:&lt;/b&gt; AMBRA1: autophagy and beclin 1 regulator 1; ATG: autophagy related; BafA1: bafilomycin A&lt;sub&gt;1&lt;/sub&gt;; BNIP1: BCL2 interacting protein 1; BNIP3: BCL2 interacting protein 3; BNIP3L/NIX: BCL2 interacting protein 3-like; CALCOCO2/NDP52: calcium binding and coiled-coil domain 2; CCPG1: cell cycle progression 1; CV: coefficients of variations; CCCP: carbonyl cyanide m-chlorophenyl hydrazone; DFP: deferiprone; ER: endoplasmic reticulum; FKBP8: FKBP prolyl isomerase 8; GABARAPL: GABA type A receptor associated protein like; LC: liquid chromatography; LOD: limit of detection; LOQ: limit of quantification; MAP1LC3: microtubule associated protein 1 light chain 3; MS: mass spectrometry; NCOA4: nuclear receptor coactivator 4; NBR1: NBR1 autophagy cargo receptor; NUFIP1: nuclear FMR1 interacting protein 1; OPTN: optineurin; PHB2: prohibitin 2; PNPLA2/ATGL: patatin like phospholipase domain containing 2; POI: protein of interest; PTM: posttranslational modification; PRM: parallel reaction monitoring; RB1CC1/FIP200: RB1 inducible coiled-coil 1; RETREG1/FAM134B: reticulophagy regulator 1; RPS6KB1: ribosomal protein S6 kinase B1; RTN3: reticulon 3; SARs: selective autophagy receptors; SQSTM1/p62: sequestosome 1; STBD1: sta","PeriodicalId":93893,"journal":{"name":"Autophagy","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142156931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"MLKL-USP7-UBA52 signaling is indispensable for autophagy in brain through maintaining ubiquitin homeostasis.","authors":"Zhigang Zhang, Shuai Chen, Shirui Jun, Xirong Xu, Yuchuan Hong, Xifei Yang, Liangyu Zou, You-Qiang Song, Yu Chen, Jie Tu","doi":"10.1080/15548627.2024.2395727","DOIUrl":"10.1080/15548627.2024.2395727","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Individuals with genetic elimination of &lt;i&gt;MLKL&lt;/i&gt; (mixed lineage kinase domain like pseudokinase) exhibit an increased susceptibility to neurodegenerative diseases like Alzheimer disease (AD). However, the mechanism is not yet fully understood. Here, we observed significant compromise in macroautophagy/autophagy in the brains of &lt;i&gt;mlkl&lt;/i&gt; knockout (KO) mice, as evidenced by the downregulation of BECN1/Beclin1 and ULK1 (unc-51 like autophagy activating kinase 1). We identified UBA52 (ubiquitin A-52 residue ribosomal protein fusion product 1) as the binding partner of MLKL under physiological conditions. Loss of &lt;i&gt;Mlkl&lt;/i&gt; induced a decrease in ubiquitin levels by preventing UBA52 cleavage. Furthermore, we demonstrated that the deubiquitinase (DUB) USP7 (ubiquitin specific peptidase 7) mediates the processing of UBA52, which is regulated by MLKL. Moreover, our results indicated that the reduction of BECN1 and ULK1 upon &lt;i&gt;Mlkl&lt;/i&gt; loss is attributed to a decrease in their lysine 63 (K63)-linked polyubiquitination. Additionally, single-nucleus RNA sequencing revealed that the loss of &lt;i&gt;Mlkl&lt;/i&gt; resulted in the disruption of multiple neurodegenerative disease-related pathways, including those associated with AD. These results were consistent with the observation of cognitive impairment in &lt;i&gt;mlkl&lt;/i&gt; KO mice and exacerbation of AD pathologies in an AD mouse model with &lt;i&gt;mlkl&lt;/i&gt; deletion. Taken together, our findings demonstrate that MLKL-USP7-UBA52 signaling is required for autophagy in brain through maintaining ubiquitin homeostasis, and highlight the contribution of &lt;i&gt;Mlkl&lt;/i&gt; loss-induced ubiquitin deficits to the development of neurodegeneration. Thus, the maintenance of adequate levels of ubiquitin may provide a novel perspective to protect individuals from multiple neurodegenerative diseases through regulating autophagy.&lt;b&gt;Abbreviations&lt;/b&gt;: 4HB: four-helix bundle; AAV: adeno-associated virus; AD: Alzheimer disease; AIF1: allograft inflammatory factor 1; APOE: apolipoprotein E; APP: amyloid beta precursor protein; Aβ: amyloid β; BECN1: beclin 1; co-IP: co-immunoprecipitation; DEGs: differentially expressed genes; DLG4: discs large MAGUK scaffold protein 4; DUB: deubiquitinase; EBSS: Earle's balanced salt solution; GFAP: glial fibrillary acidic protein; HRP: horseradish peroxidase; IL1B: interleukin 1 beta; IL6: interleukin 6; IPed: immunoprecipitated; KEGG: Kyoto Encyclopedia of Genes and Genomes; KO: knockout; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MLKL: mixed lineage kinase domain like pseudokinase; NSA: necrosulfonamide; OPCs: oligodendrocyte precursor cells; PFA: paraformaldehyde; PsKD: pseudo-kinase domain; SYP: synaptophysin; UB: ubiquitin; UBA52: ubiquitin A-52 residue ribosomal protein fusion product 1; UCHL3: ubiquitin C-terminal hydrolase L3; ULK1: unc-51 like autophagy activating kinase 1; UMAP: uniform manifold approximation and projection; UPS: ubiquitin-proteasome system; USP7: ubiquitin specif","PeriodicalId":93893,"journal":{"name":"Autophagy","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142082829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correction.","authors":"","doi":"10.1080/15548627.2024.2401222","DOIUrl":"https://doi.org/10.1080/15548627.2024.2401222","url":null,"abstract":"","PeriodicalId":93893,"journal":{"name":"Autophagy","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142303282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bunyavirus SFTSV nucleoprotein exploits TUFM-mediated mitophagy to impair antiviral innate immunity.","authors":"Wen-Kang Zhang, Jia-Min Yan, Min Chu, Bang Li, Xiao-Lan Gu, Ze-Zheng Jiang, Ze-Min Li, Pan-Pan Liu, Tian-Mei Yu, Chuan-Min Zhou, Xue-Jie Yu","doi":"10.1080/15548627.2024.2393067","DOIUrl":"10.1080/15548627.2024.2393067","url":null,"abstract":"<p><p>Severe fever with thrombocytopenia syndrome is an emerging viral hemorrhagic fever caused by a tick-borne bunyavirus, severe fever with thrombocytopenia syndrome virus (SFTSV), with a high case fatality. We previously found that SFTSV nucleoprotein (NP) induces macroautophagy/autophagy to facilitate virus replication. However, the role of NP in antagonizing host innate immunity remains unclear. Mitophagy, a selected form of autophagy, eliminates damaged mitochondria to maintain mitochondrial homeostasis. Here, we demonstrate that SFTSV NP triggers mitophagy to degrade MAVS (mitochondrial antiviral signaling protein), thereby blocking MAVS-mediated antiviral signaling to escape the host immune response. Mechanistically, SFTSV NP translocates to mitochondria by interacting with TUFM (Tu translation elongation factor, mitochondrial), and mediates mitochondrial sequestration into phagophores through interacting with LC3, thus inducing mitophagy. Notably, the N-terminal LC3-interacting region (LIR) motif of NP is essential for mitophagy induction. Collectively, our results demonstrated that SFTSV NP serves as a novel virulence factor, inducing TUFM-mediated mitophagy to degrade MAVS and evade the host immune response.<b>Abbreviation:</b> 3-MA: 3-methyladenine; ACTB: actin beta; co-IP: co-immunoprecipitation; CQ: chloroquine; DAPI: 4',6-diamidino-2-phenylindole, dihydrochloride; DMSO: dimethyl sulfoxide; FCCP: carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone; GFP: green fluorescent protein; HTNV: Hantan virus; IAV: influenza A virus; IFN: interferon; LAMP1: lysosomal associated membraneprotein 1; LIR: LC3-interacting region; MAP1LC3B/LC3B: microtubule associatedprotein 1 light chain 3 beta; MAVS: mitochondrial antiviral signaling protein; Mdivi-1: mitochondrial division inhibitor 1; MOI: multiplicity of infection; MT-CO2/COXII: mitochondrially encoded cytochrome C oxidase II; NP: nucleoprotein; NSs: nonstructural proteins; poly(I:C): polyinosinic:polycytidylic acid; RIGI: RNA sensor RIG-I; RLR: RIGI-like receptor; SFTSV: severe fever withthrombocytopenia syndrome virus; TCID50: 50% tissue culture infectiousdose; TIMM23: translocase of inner mitochondrial membrane 23; TOMM20:translocase of outer mitochondrial membrane 20; TUFM: Tu translation elongationfactor, mitochondrial.</p>","PeriodicalId":93893,"journal":{"name":"Autophagy","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142074822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A surge in endogenous spermidine is essential for rapamycin-induced autophagy and longevity.","authors":"Sebastian J Hofer, Ioanna Daskalaki, Mahmoud Abdellatif, Ulrich Stelzl, Simon Sedej, Nektarios Tavernarakis, Guido Kroemer, Frank Madeo","doi":"10.1080/15548627.2024.2396793","DOIUrl":"10.1080/15548627.2024.2396793","url":null,"abstract":"<p><p>Acute nutrient deprivation (fasting) causes an immediate increase in spermidine biosynthesis in yeast, flies, mice and humans, as corroborated in four independent clinical studies. This fasting-induced surge in spermidine constitutes the critical first step of a phylogenetically conserved biochemical cascade that leads to spermidine-dependent hypusination of EIF5A (eukaryotic translation initiation factor 5A), which favors the translation of the pro-macroautophagic/autophagic TFEB (transcription factor EB), and hence an increase in autophagic flux. We observed that genetic or pharmacological inhibition of the spermidine increase by inhibition of ODC1 (ornithine decarboxylase 1) prevents the pro-autophagic and antiaging effects of fasting in yeast, nematodes, flies and mice. Moreover, knockout or knockdown of the enzymes required for EIF5A hypusination abolish fasting-mediated autophagy enhancement and longevity extension in these organisms. Of note, autophagy and longevity induced by rapamycin obey the same rule, meaning that they are tied to an increase in spermidine synthesis. These findings indicate that spermidine is not only a \"caloric restriction mimetic\" in the sense that its supplementation mimics the beneficial effects of nutrient deprivation on organismal health but that it is also an obligatory downstream effector of the antiaging effects of fasting and rapamycin.<b>Abbreviation</b>: EIF5A: eukaryotic translation initiation factor 5A; IGF1: insulin like growth factor 1; MTOR: mechanistic target of rapamycin kinase; ODC1: ornithine decarboxylase 1; TFEB: transcription factor EB.</p>","PeriodicalId":93893,"journal":{"name":"Autophagy","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142115909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"USP8 promotes intracellular infection by enhancing ESCRT-mediated membrane repair, limiting xenophagy, and reducing oxidative stress.","authors":"Pallavi Chandra, Jennifer A Philips","doi":"10.1080/15548627.2024.2395134","DOIUrl":"10.1080/15548627.2024.2395134","url":null,"abstract":"<p><p>The host ESCRT-machinery repairs damaged endolysosomal membranes. If damage persists, selective macroautophagy/autophagy clears the damaged compartment. <i>Mycobacterium tuberculosis</i> (Mtb) is an intracellular pathogen that damages the phagosomal membrane and targets ESCRT-mediated repair as part of its virulence program. The E3 ubiquitin ligases PRKN and SMURF1 promote autophagic capture of damaged, Mtb-containing phagosomes. Because ubiquitination is a reversible process, we anticipated that host deubiquitinases (DUBs) would also be involved. Here, we screened all predicted mouse DUBs for their role in ubiquitin targeting and control of intracellular Mtb. We show that USP8 (ubiquitin specific peptidase 8) colocalizes with intracellular Mtb, recognizes phagosomal membrane damage, and is required for ESCRT-dependent membrane repair. Furthermore, we show that USP8 regulates the NFE2L2/NRF2-dependent antioxidant signature. Taken together, our study demonstrates a central role of USP8 in promoting Mtb intracellular growth by promoting phagosomal membrane repair, limiting ubiquitin-driven selective autophagy, and reducing oxidative stress.<b>Abbreviation:</b> BMDMs: bone marrow-derived macrophages; CFUs: colony-forming units; DUB: deubiquitinase; ESCRT: endosomal sorting complexes required for transport; LLOMe: L-leucyl-L-leucine methyl ester; MFI: mean fluorescence intensity; MOI: multiplicity of infection; Mtb: <i>Mycobacterium tuberculosis</i>; NFE2L2/NRF2: nuclear factor, erythroid derived 2, like 2; PMA: phorbol 12-myristate 13-acetate; ROS: reactive oxygen species; USP8: ubiquitin specific peptidase 8.</p>","PeriodicalId":93893,"journal":{"name":"Autophagy","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142047647","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impaired degradation of PLCG1 by chaperone-mediated autophagy promotes cellular senescence and intervertebral disc degeneration.","authors":"Zhangrong Cheng, Weikang Gan, Qian Xiang, Kangcheng Zhao, Haiyang Gao, Yuhang Chen, Pengzhi Shi, Anran Zhang, Gaocai Li, Yu Song, Xiaobo Feng, Cao Yang, Yukun Zhang","doi":"10.1080/15548627.2024.2395797","DOIUrl":"10.1080/15548627.2024.2395797","url":null,"abstract":"<p><p>Defects in chaperone-mediated autophagy (CMA) are associated with cellular senescence, but the mechanism remains poorly understood. Here, we found that CMA inhibition induced cellular senescence in a calcium-dependent manner and identified its role in TNF-induced senescence of nucleus pulposus cells (NPC) and intervertebral disc degeneration. Based on structural and functional proteomic screens, PLCG1 (phospholipase C gamma 1) was predicted as a potential substrate for CMA deficiency to affect calcium homeostasis. We further confirmed that PLCG1 was a key mediator of CMA in the regulation of intracellular calcium flux. Aberrant accumulation of PLCG1 caused by CMA blockage resulted in calcium overload, thereby inducing NPC senescence. Immunoassays on human specimens showed that reduced LAMP2A, the rate-limiting protein of CMA, or increased PLCG1 was associated with disc senescence, and the TNF-induced disc degeneration in rats was inhibited by overexpression of <i>Lamp2a</i> or knockdown of <i>Plcg1</i>. Because CMA dysregulation, calcium overload, and cellular senescence are common features of disc degeneration and other age-related degenerative diseases, the discovery of actionable molecular targets that can link these perturbations may have therapeutic value.<b>Abbreviation:</b> ATRA: all-trans-retinoic acid; BrdU: bromodeoxyuridine; CDKN1A/p21: cyclin dependent kinase inhibitor 1A; CDKN2A/p16-INK4A: cyclin dependent kinase inhibitor 2A; CMA: chaperone-mediated autophagy; DHI: disc height index; ER: endoplasmic reticulum; IP: immunoprecipitation; IP3: inositol 1,4,5-trisphosphate; ITPR/IP3R: inositol 1,4,5-trisphosphate receptor; IVD: intervertebral disc; IVDD: intervertebral disc degeneration; KD: knockdown; KO: knockout; Leu: leupeptin; MRI: magnetic resonance imaging; MS: mass spectrometry; N/L: NH₄Cl and leupeptin; NP: nucleus pulposus; NPC: nucleus pulposus cells; PI: protease inhibitors; PLC: phospholipase C; PLCG1: phospholipase C gamma 1; ROS: reactive oxygen species; RT-qPCR: real-time quantitative reverse transcription PCR; SA-GLB1/β-gal: senescence-associated galactosidase beta 1; SASP: senescence-associated secretory phenotype; STV: starvation; TMT: tandem mass tag; TNF: tumor necrosis factor; TP53: tumor protein p53; UPS: ubiquitin-proteasome system.</p>","PeriodicalId":93893,"journal":{"name":"Autophagy","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142115911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"TRIM21-mediated ubiquitination of SQSTM1/p62 abolishes its Ser403 phosphorylation and enhances palmitic acid cytotoxicity.","authors":"Peng Yang, Shenglan Gao, Jianliang Shen, Tong Liu, Kevin Lu, Xinlu Han, Jun Wang, Hong-Min Ni, Wen-Xing Ding, Hong Li, Ji-An Pan, Kesong Peng, Wei-Xing Zong","doi":"10.1080/15548627.2024.2394308","DOIUrl":"10.1080/15548627.2024.2394308","url":null,"abstract":"<p><p>Long-chain free fatty acids (FFAs) accumulation and oxidative toxicity is a major cause for several pathological conditions. The mechanisms underlying FFA cytotoxicity remain elusive. Here we show that palmitic acid (PA), the most abundant FFA in the circulation, induces S403 phosphorylation of SQSTM1/p62 (sequestosome 1) and its aggregation, which sequesters KEAP1 and activates the non-canonical SQSTM1-KEAP1-NFE2L2 antioxidant pathway. The PA-induced SQSTM1 S403 phosphorylation and aggregation are dependent on SQSTM1 K7-D69 hydrogen bond formation and dimerization in the Phox and Bem1 (PB1) domain, which facilitates the recruitment of TBK1 that phosphorylates SQSTM1 S403. The ubiquitin E3 ligase TRIM21 ubiquitinates SQSTM1 at the K7 residue and abolishes the PB1 dimerization, S403 phosphorylation, and SQSTM1 aggregation. TRIM21 is oxidized at C92, C111, and C114 to form disulfide bonds that lead to its oligomerization and decreased E3 activity. Mutagenizing the three C residues to S (3CS) abolishes TRIM21 oligomerization and increases its E3 activity. TRIM21 ablation leads to decreased SQSTM1 K7 ubiquitination, hence elevated SQSTM1 S403 phosphorylation and aggregation, which confers protection against PA-induced oxidative stress and cytotoxicity. Therefore, TRIM21 is a negative regulator of SQSTM1 phosphorylation, aggregation, and the antioxidant sequestration function. TRIM21 is oxidized to reduce its E3 activity that helps enhance the SQSTM1-KEAP1-NFE2L2 antioxidant pathway. Inhibition of TRIM21 May be a viable strategy to protect tissues from lipotoxicity resulting from long-chain FFAs.<b>Abbreviations:</b> ER: endoplasmic reticulum; FFA: free fatty acid; HMOX1/HO-1: heme oxygenase 1; IB: immunoblotting; IF: immunofluorescence; IP: immunoprecipitation; KEAP1: kelch like ECH associated protein 1; MASH: metabolic dysfunction-associated steatohepatitis; MEF: mouse embryonic fibroblast; NFE2L2/Nrf2: NFE2 like BZIP transcription factor 2; PA: palmitic acid; PB1: Phox and Bem 1; ROS: reactive oxygen species; SLD: steatotic liver disease; SQSTM1: sequestosome 1; TBK1: TANK-binding kinase 1; TRIM21: tripartite motif containing 21.</p>","PeriodicalId":93893,"journal":{"name":"Autophagy","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142019834","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"BIN1 deficiency enhances ULK3-dependent autophagic flux and reduces dendritic size in mouse hippocampal neurons.","authors":"Yuxi Jin, Lin Zhao, Yanli Zhang, Tingzhen Chen, Huili Shi, Huaiqing Sun, Shixin Ding, Sijia Chen, Haifeng Cao, Guannan Zhang, Qian Li, Junying Gao, Ming Xiao, Chengyu Sheng","doi":"10.1080/15548627.2024.2393932","DOIUrl":"10.1080/15548627.2024.2393932","url":null,"abstract":"<p><p>Genome-wide association studies identified variants around the <i>BIN1</i> (bridging integrator 1) gene locus as prominent risk factors for late-onset Alzheimer disease. In the present study, we decreased the expression of BIN1 in mouse hippocampal neurons to investigate its neuronal function. <i>Bin1</i> knockdown via RNAi reduced the dendritic arbor size in primary cultured hippocampal neurons as well as in mature Cornu Ammonis 1 excitatory neurons. The AAV-mediated <i>Bin1</i> RNAi knockdown also generated a significant regional volume loss around the injection sites at the organ level, as revealed by 7-Tesla structural magnetic resonance imaging, and an impaired spatial reference memory performance in the Barnes maze test. Unexpectedly, <i>Bin1</i> knockdown led to concurrent activation of both macroautophagy/autophagy and MTOR (mechanistic target of rapamycin kinase) complex 1 (MTORC1). Autophagy inhibition with the lysosome inhibitor chloroquine effectively mitigated the <i>Bin1</i> knockdown-induced dendritic regression. The subsequent molecular studydemonstrated that increased expression of ULK3 (unc-51 like kinase 3), which is MTOR-insensitive, supported autophagosome formation in BIN1 deficiency. Reducing ULK3 activity with SU6668, a receptor tyrosine kinase inhibitor, or decreasing neuronal ULK3 expression through AAV-mediated RNAi, significantly attenuated <i>Bin1</i> knockdown-induced hippocampal volume loss and spatial memory decline. In Alzheimer disease patients, the major neuronal isoform of BIN1 is specifically reduced. Our work suggests this reduction is probably an important molecular event that increases the autophagy level, which might subsequently promote brain atrophy and cognitive impairment through reducing dendritic structures, and ULK3 is a potential interventional target for relieving these detrimental effects.<b>Abbreviations</b>: AV: adeno-associated virus; Aβ: amyloid-β; ACTB: actin, beta; AD: Alzheimer disease; Aduk: Another Drosophila Unc-51-like kinase; AKT1: thymoma viral proto-oncogene 1; AMPK: AMP-activated protein kinase; AP: autophagosome; BafA1: bafilomycin A₁; BDNF: brain derived neurotrophic factor; BIN1: bridging integrator 1; BIN1-iso1: BIN1, isoform 1; CA1: cornu Ammonis 1; CA3: cornu Ammonis 3; CLAP: clathrin and adapter binding; CQ: chloroquine; DMEM: Dulbecco's modified Eagle medium; EGFP: enhanced green fluorescent protein; GWAS: genome-wide association study; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MRI: magnetic resonance imaging; MTOR; mechanistic target of rapamycin kinase; MTORC1: MTOR complex 1; PET: positron emission tomography; qRT-PCR: real-time quantitative reverse transcription PCR; ROS: reactive oxygen species; RPS6KB1: ribosomal protein S6 kinase B1; TFEB: transcription factor EB; ULK1: unc-51 like kinase 1; ULK3: unc-51 like kinase 3.</p>","PeriodicalId":93893,"journal":{"name":"Autophagy","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142019885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}