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Gross AS, Ghillebert R, Schuetter M, Reinartz E, Rowland A, Bishop BC, Stumpe M, Dengjel J, Graef M. A metabolite sensor subunit of the Atg1/ULK complex regulates selective autophagy. Nat Cell Biol 2024; 26:366-377. [PMID: 38316984 PMCID: PMC10940145 DOI: 10.1038/s41556-024-01348-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 01/03/2024] [Indexed: 02/07/2024]
Abstract
Cells convert complex metabolic information into stress-adapted autophagy responses. Canonically, multilayered protein kinase networks converge on the conserved Atg1/ULK kinase complex (AKC) to induce non-selective and selective forms of autophagy in response to metabolic changes. Here we show that, upon phosphate starvation, the metabolite sensor Pho81 interacts with the adaptor subunit Atg11 at the AKC via an Atg11/FIP200 interaction motif to modulate pexophagy by virtue of its conserved phospho-metabolite sensing SPX domain. Notably, core AKC components Atg13 and Atg17 are dispensable for phosphate starvation-induced autophagy revealing significant compositional and functional plasticity of the AKC. Our data indicate that, instead of functioning as a selective autophagy receptor, Pho81 compensates for partially inactive Atg13 by promoting Atg11 phosphorylation by Atg1 critical for pexophagy during phosphate starvation. Our work shows Atg11/FIP200 adaptor subunits bind not only selective autophagy receptors but also modulator subunits that convey metabolic information directly to the AKC for autophagy regulation.
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Affiliation(s)
- A S Gross
- Max Planck Research Group of Autophagy and Cellular Ageing, Max Planck Institute for Biology of Ageing, Cologne, Germany
- Gregor Mendel Institute of Molecular Plant Biology, Vienna Biocenter, Vienna, Austria
| | - R Ghillebert
- Max Planck Research Group of Autophagy and Cellular Ageing, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - M Schuetter
- Max Planck Research Metabolomics Core Facility, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - E Reinartz
- Max Planck Research Group of Autophagy and Cellular Ageing, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - A Rowland
- Max Planck Research Group of Autophagy and Cellular Ageing, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - B C Bishop
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - M Stumpe
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - J Dengjel
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - M Graef
- Max Planck Research Group of Autophagy and Cellular Ageing, Max Planck Institute for Biology of Ageing, Cologne, Germany.
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA.
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2
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Chen Y, Tan X, Zhang W, Li Y, Deng X, Zeng J, Huang L, Ma X. Natural products targeting macroautophagy signaling in hepatocellular carcinoma therapy: Recent evidence and perspectives. Phytother Res 2024; 38:1623-1650. [PMID: 38302697 DOI: 10.1002/ptr.8103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 12/07/2023] [Accepted: 12/16/2023] [Indexed: 02/03/2024]
Abstract
Hepatocellular carcinoma (HCC), presently the second leading cause of global cancer-related mortality, continues to pose significant challenges in the realm of medical oncology, impacting both clinical drug selection and mechanistic research. Recent investigations have unveiled autophagy-related signaling as a promising avenue for HCC treatment. A growing body of research has highlighted the pivotal role of autophagy-modulating natural products in inhibiting HCC progression. In this context, we provide a concise overview of the fundamental autophagy mechanism and delineate the involvement of autophagic signaling pathways in HCC development. Additionally, we review pertinent studies demonstrating how natural products regulate autophagy to mitigate HCC. Our findings indicate that natural products exhibit cytotoxic effects through the induction of excessive autophagy, simultaneously impeding HCC cell proliferation by autophagy inhibition, thereby depriving HCC cells of essential energy. These effects have been associated with various signaling pathways, including PI3K/AKT, MAPK, AMPK, Wnt/β-catenin, Beclin-1, and ferroautophagy. These results underscore the considerable therapeutic potential of natural products in HCC treatment. However, it is important to note that the present study did not establish definitive thresholds for autophagy induction or inhibition by natural products. Further research in this domain is imperative to gain comprehensive insights into the dual role of autophagy, equipping us with a better understanding of this double-edged sword in HCC management.
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Affiliation(s)
- Yuan Chen
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Xiyue Tan
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Wenwen Zhang
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Yubing Li
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Xinyu Deng
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Jinhao Zeng
- Department of Gastroenterology, Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu, China
- TCM Regulating Metabolic Diseases Key Laboratory of Sichuan Province, Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Lihua Huang
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Xiao Ma
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China
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3
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Kang Y, Lin W, Nagy PD. Subversion of selective autophagy for the biogenesis of tombusvirus replication organelles inhibits autophagy. PLoS Pathog 2024; 20:e1012085. [PMID: 38484009 DOI: 10.1371/journal.ppat.1012085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 03/26/2024] [Accepted: 02/29/2024] [Indexed: 03/27/2024] Open
Abstract
Elaborate viral replication organelles (VROs) are formed to support positive-strand RNA virus replication in infected cells. VRO formation requires subversion of intracellular membranes by viral replication proteins. Here, we showed that the key ATG8f autophagy protein and NBR1 selective autophagy receptor were co-opted by Tomato bushy stunt virus (TBSV) and the closely-related carnation Italian ringspot virus. Knockdown of ATG8f or NBR1 in plants led to reduced tombusvirus replication, suggesting pro-viral function for selective autophagy. BiFC and proximity-labeling experiments showed that the TBSV p33 replication protein interacted with ATG8f and NBR1 to recruit them to VROs. In addition, we observed that several core autophagy proteins, such as ATG1a, ATG4, ATG5, ATG101 and the plant-specific SH3P2 autophagy adaptor proteins were also re-localized to TBSV VROs, suggesting that TBSV hijacks the autophagy machinery in plant cells. We demonstrated that subversion of autophagy components facilitated the recruitment of VPS34 PI3 kinase and enrichment of phospholipids, such as phosphatidylethanolamine and PI3P phosphoinositide in the VRO membranes. Hijacking of autophagy components into TBSV VROs led to inhibition of autophagic flux. We also found that a fraction of the subverted ATG8f and NBR1 was sequestered in biomolecular condensates associated with VROs. We propose that the VRO-associated condensates trap those autophagy proteins, taking them away from the autophagy pathway. Overall, tombusviruses hijack selective autophagy to provide phospholipid-rich membranes for replication and to regulate the antiviral autophagic flux.
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Affiliation(s)
- Yuanrong Kang
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky, United States of America
| | - Wenwu Lin
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky, United States of America
| | - Peter D Nagy
- Department of Plant Pathology, University of Kentucky, Lexington, Kentucky, United States of America
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4
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Ma X, Zhang H. Compositional plasticity of the Atg1 complex. Nat Cell Biol 2024; 26:313-315. [PMID: 38316983 DOI: 10.1038/s41556-023-01340-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Affiliation(s)
- Xiaoli Ma
- New Cornerstone Science Laboratory, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Hong Zhang
- New Cornerstone Science Laboratory, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
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5
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Hanley SE, Willis SD, Doyle SJ, Strich R, Cooper KF. Ksp1 is an autophagic receptor protein for the Snx4-assisted autophagy of Ssn2/Med13. Autophagy 2024; 20:397-415. [PMID: 37733395 PMCID: PMC10813586 DOI: 10.1080/15548627.2023.2259708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 09/11/2023] [Indexed: 09/22/2023] Open
Abstract
Ksp1 is a casein II-like kinase whose activity prevents aberrant macroautophagy/autophagy induction in nutrient-rich conditions in yeast. Here, we describe a kinase-independent role of Ksp1 as a novel autophagic receptor protein for Ssn2/Med13, a known cargo of Snx4-assisted autophagy of transcription factors. In this pathway, a subset of conserved transcriptional regulators, Ssn2/Med13, Rim15, and Msn2, are selectively targeted for vacuolar proteolysis following nitrogen starvation, assisted by the sorting nexin heterodimer Snx4-Atg20. Here we show that phagophores also engulf Ksp1 alongside its cargo for vacuolar proteolysis. Ksp1 directly associates with Atg8 following nitrogen starvation at the interface of an Atg8-family interacting motif (AIM)/LC3-interacting region (LIR) in Ksp1 and the LIR/AIM docking site (LDS) in Atg8. Mutating the LDS site prevents the autophagic degradation of Ksp1. However, deletion of the C terminal canonical AIM still permitted Ssn2/Med13 proteolysis, suggesting that additional non-canonical AIMs may mediate the Ksp1-Atg8 interaction. Ksp1 is recruited to the perivacuolar phagophore assembly site by Atg29, a member of the trimeric scaffold complex. This interaction is independent of Atg8 and Snx4, suggesting that Ksp1 is recruited early to phagophores, with Snx4 delivering Ssn2/Med13 thereafter. Finally, normal cell survival following prolonged nitrogen starvation requires Ksp1. Together, these studies define a kinase-independent role for Ksp1 as an autophagic receptor protein mediating Ssn2/Med13 degradation. They also suggest that phagophores built by the trimeric scaffold complex are capable of receptor-mediated autophagy. These results demonstrate the dual functionality of Ksp1, whose kinase activity prevents autophagy while it plays a scaffolding role supporting autophagic degradation.Abbreviations: 3-AT: 3-aminotriazole; 17C: Atg17-Atg31-Atg29 trimeric scaffold complex; AIM: Atg8-family interacting motif; ATG: autophagy related; CKM: CDK8 kinase module; Cvt: cytoplasm-to-vacuole targeting; IDR: intrinsically disordered region; LIR: LC3-interacting region; LDS: LIR/AIM docking site; MoRF: molecular recognition feature; NPC: nuclear pore complex; PAS: phagophore assembly site; PKA: protein kinase A; RBP: RNA-binding protein; UPS: ubiquitin-proteasome system. SAA-TF: Snx4-assisted autophagy of transcription factors; Y2H: yeast two-hybrid.
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Affiliation(s)
- Sara E. Hanley
- Department of Molecular Biology, Rowan-Virtua School of Translational Biomedical Engineering & Sciences, Rowan University, Stratford, NJ, USA
| | - Stephen D. Willis
- Department of Molecular Biology, Rowan-Virtua School of Translational Biomedical Engineering & Sciences, Rowan University, Stratford, NJ, USA
| | - Steven J. Doyle
- Department of Molecular Biology, Rowan-Virtua School of Translational Biomedical Engineering & Sciences, Rowan University, Stratford, NJ, USA
- School of Osteopathic Medicine, Rowan University, Stratford, NJ, USA
| | - Randy Strich
- Department of Molecular Biology, Rowan-Virtua School of Translational Biomedical Engineering & Sciences, Rowan University, Stratford, NJ, USA
| | - Katrina F. Cooper
- Department of Molecular Biology, Rowan-Virtua School of Translational Biomedical Engineering & Sciences, Rowan University, Stratford, NJ, USA
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6
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Lecordier L, Heo P, Graversen JH, Hennig D, Skytthe MK, Cornet d'Elzius A, Pincet F, Pérez-Morga D, Pays E. Apolipoproteins L1 and L3 control mitochondrial membrane dynamics. Cell Rep 2023; 42:113528. [PMID: 38041817 PMCID: PMC10765320 DOI: 10.1016/j.celrep.2023.113528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 11/08/2023] [Accepted: 11/17/2023] [Indexed: 12/04/2023] Open
Abstract
Apolipoproteins L1 and L3 (APOLs) are associated at the Golgi with the membrane fission factors phosphatidylinositol 4-kinase-IIIB (PI4KB) and non-muscular myosin 2A. Either APOL1 C-terminal truncation (APOL1Δ) or APOL3 deletion (APOL3-KO [knockout]) reduces PI4KB activity and triggers actomyosin reorganization. We report that APOL3, but not APOL1, controls PI4KB activity through interaction with PI4KB and neuronal calcium sensor-1 or calneuron-1. Both APOLs are present in Golgi-derived autophagy-related protein 9A vesicles, which are involved in PI4KB trafficking. Like APOL3-KO, APOL1Δ induces PI4KB dissociation from APOL3, linked to reduction of mitophagy flux and production of mitochondrial reactive oxygen species. APOL1 and APOL3, respectively, can interact with the mitophagy receptor prohibitin-2 and the mitophagosome membrane fusion factor vesicle-associated membrane protein-8 (VAMP8). While APOL1 conditions PI4KB and APOL3 involvement in mitochondrion fission and mitophagy, APOL3-VAMP8 interaction promotes fusion between mitophagosomal and endolysosomal membranes. We propose that APOL3 controls mitochondrial membrane dynamics through interactions with the fission factor PI4KB and the fusion factor VAMP8.
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Affiliation(s)
- Laurence Lecordier
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles, 6041 Gosselies, Belgium
| | - Paul Heo
- Laboratoire de Physique de l'Ecole Normale Supérieure, Ecole Normale Supérieure (ENS), Université Paris Sciences et Lettres (PSL), CNRS, Sorbonne Université, Université Paris-Cité, 75005 Paris, France; Institute of Psychiatry and Neuroscience of Paris, INSERM U1266, 75014 Paris, France
| | - Jonas H Graversen
- Department of Molecular Medicine, Cancer and Inflammation Research, University of Southern Denmark, 5000 Odense C, Denmark
| | - Dorle Hennig
- Department of Molecular Medicine, Cancer and Inflammation Research, University of Southern Denmark, 5000 Odense C, Denmark
| | - Maria Kløjgaard Skytthe
- Department of Molecular Medicine, Cancer and Inflammation Research, University of Southern Denmark, 5000 Odense C, Denmark
| | | | - Frédéric Pincet
- Laboratoire de Physique de l'Ecole Normale Supérieure, Ecole Normale Supérieure (ENS), Université Paris Sciences et Lettres (PSL), CNRS, Sorbonne Université, Université Paris-Cité, 75005 Paris, France
| | - David Pérez-Morga
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles, 6041 Gosselies, Belgium; Center for Microscopy and Molecular Imaging (CMMI), Université Libre de Bruxelles, 6041 Gosselies, Belgium
| | - Etienne Pays
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles, 6041 Gosselies, Belgium.
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7
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Andhare D, Ragusa MJ. A new GUV-based assay to reconstitute membrane tethering in vitro demonstrates the vesicle tethering ability of the selective autophagy scaffold Atg11. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.19.572332. [PMID: 38187578 PMCID: PMC10769207 DOI: 10.1101/2023.12.19.572332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
Membrane tethering is essential for the generation of organelle contact sites and to anchor incoming vesicles to their target membranes before vesicle fusion. During autophagy in yeast, tethering of 30 nm vesicles to cargo is one of the first steps in the generation of the isolation membrane that engulfs the cargo to be degraded. While membrane tethering is critical for cellular function, many of the current biochemical techniques to assay for membrane tethering rely on indirect readouts and are limited in their ability to monitor protein localization at sites of tethering. As such, we developed a fluorescence-microscopy-based GUV liposome tethering assay (GLT) to directly visualize membrane tethering and monitor protein localization at tethering sites simultaneously. We initially used GLT with engineered membrane tethers to demonstrate the ease of use, versatility and sensitivity of the assay. We also demonstrated that the selective autophagy scaffolding protein Atg11 can bind, and tether negatively charged membranes but is unable to bind GUVs mimicking the charge of the outer mitochondrial membrane. Atg11 instead requires the selective autophagy receptor Atg32 to be recruited to mitochondrial membranes. Lastly, we demonstrate that Atg11 bound to Atg32 on GUVs can tether negatively charged vesicles to GUVs. Collectively, our results reconstitute one of the first steps during the initiation of mitochondrial autophagy and highlight the versatility of GLT to study a range of membrane tethering events biochemically.
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Affiliation(s)
- Devika Andhare
- Department of Chemistry, Dartmouth College, Hanover, NH 03755, USA
| | - Michael J Ragusa
- Department of Chemistry, Dartmouth College, Hanover, NH 03755, USA
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8
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Folger A, Chen C, Kabbaj MH, Frey K, Wang Y. Neurodegenerative disease-associated inclusion bodies are cleared by selective autophagy in budding yeast. AUTOPHAGY REPORTS 2023; 2:2236407. [PMID: 37680383 PMCID: PMC10482306 DOI: 10.1080/27694127.2023.2236407] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 06/13/2023] [Accepted: 07/06/2023] [Indexed: 09/09/2023]
Abstract
Protein misfolding, aggregation, and accumulation cause neurodegenerative disorders. One such disorder, Huntington's disease, is caused by an increased number of glutamine-encoding trinucleotide repeats CAG in the first exon of the huntingtin (HTT) gene. Mutant proteins of Htt exon 1 with polyglutamine expansion are prone to aggregation and form pathological inclusion bodies in neurons. Extensive studies have shown that misfolded proteins are cleared by the ubiquitin-proteasome system or autophagy to alleviate their cytotoxicity. Misfolded proteins can form small soluble aggregates or large insoluble inclusion bodies. Previous works have elucidated the role of autophagy in the clearance of misfolded protein aggregates, but autophagic clearance of inclusion bodies remains poorly characterized. Here we use mutant Htt exon 1 with 103 polyglutamine (Htt103QP) as a model substrate to study the autophagic clearance of inclusion bodies in budding yeast. We found that the core autophagy-related proteins were required for Htt103QP inclusion body autophagy. Moreover, our evidence indicates that the autophagy of Htt103QP inclusion bodies is selective. Interestingly, Cue5/Tollip, a known autophagy receptor for aggrephagy, is dispensable for this inclusion body autophagy. From the known selective autophagy receptors in budding yeast, we identified three that are essential for inclusion body autophagy. Amyloid beta peptide (Aβ42) is a major component of amyloid plaques found in Alzheimer's disease brains. Interestingly, a similar selective autophagy pathway contributes to the clearance of Aβ42 inclusion bodies in budding yeast. Therefore, our results reveal a novel autophagic pathway specific for inclusion bodies associated with neurodegenerative diseases, which we have termed IBophagy.
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Affiliation(s)
- Austin Folger
- Department of Biomedical Sciences, College of Medicine, Florida State University, 1115 West Call Street, Tallahassee, FL 32306-4300
| | - Chuan Chen
- College of Biological Sciences, Hebei University, Baoding, China
| | - Marie-Helene Kabbaj
- Department of Biomedical Sciences, College of Medicine, Florida State University, 1115 West Call Street, Tallahassee, FL 32306-4300
| | - Karina Frey
- Department of Biological Sciences, Florida State University (undergraduate student)
| | - Yanchang Wang
- Department of Biomedical Sciences, College of Medicine, Florida State University, 1115 West Call Street, Tallahassee, FL 32306-4300
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9
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Shen ZF, Li L, Zhu XM, Liu XH, Klionsky DJ, Lin FC. Current opinions on mitophagy in fungi. Autophagy 2023; 19:747-757. [PMID: 35793406 PMCID: PMC9980689 DOI: 10.1080/15548627.2022.2098452] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 06/27/2022] [Accepted: 06/28/2022] [Indexed: 11/02/2022] Open
Abstract
Mitophagy, as one of the most important cellular processes to ensure quality control of mitochondria, aims at transporting damaged, aging, dysfunctional or excess mitochondria to vacuoles (plants and fungi) or lysosomes (mammals) for degradation and recycling. The normal functioning of mitophagy is critical for cellular homeostasis from yeasts to humans. Although the role of mitophagy has been well studied in mammalian cells and in certain model organisms, especially the budding yeast Saccharomyces cerevisiae, our understanding of its significance in other fungi, particularly in pathogenic filamentous fungi, is still at the preliminary stage. Recent studies have shown that mitophagy plays a vital role in spore production, vegetative growth and virulence of pathogenic fungi, which are very different from its roles in mammal and yeast. In this review, we summarize the functions of mitophagy for mitochondrial quality and quantity control, fungal growth and pathogenesis that have been reported in the field of molecular biology over the past two decades. These findings may help researchers and readers to better understand the multiple functions of mitophagy and provide new perspectives for the study of mitophagy in fungal pathogenesis.Abbreviations: AIM/LIR: Atg8-family interacting motif/LC3-interacting region; BAR: Bin-Amphiphysin-Rvs; BNIP3: BCL2 interacting protein 3; CK2: casein kinase 2; Cvt: cytoplasm-to-vacuole targeting; ER: endoplasmic reticulum; IMM: inner mitochondrial membrane; mETC: mitochondrial electron transport chain; OMM: outer mitochondrial membrane; OPTN: optineurin; PAS: phagophore assembly site; PD: Parkinson disease; PE: phosphatidylethanolamine; PHB2: prohibitin 2; PX: Phox homology; ROS, reactive oxygen species; TM: transmembrane.
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Affiliation(s)
- Zi-Fang Shen
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, China
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang, China
| | - Lin Li
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, China
| | - Xue-Ming Zhu
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, China
| | - Xiao-Hong Liu
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang, China
| | - Daniel J. Klionsky
- Life Sciences Institute and Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Fu-Cheng Lin
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, China
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang, China
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10
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Vargas Duarte P, Reggiori F. The Organization and Function of the Phagophore-ER Membrane Contact Sites. CONTACT (THOUSAND OAKS (VENTURA COUNTY, CALIF.)) 2023; 6:25152564231183898. [PMID: 37465355 PMCID: PMC10350784 DOI: 10.1177/25152564231183898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 06/06/2023] [Accepted: 06/06/2023] [Indexed: 07/20/2023]
Abstract
Macroautophagy is characterized by the de novo formation of double-membrane vesicles termed autophagosomes. The precursor structure of autophagosomes is a membrane cistern called phagophore, which elongates through a massive acquisition of lipids until closure. The phagophore establishes membrane-contact sites (MCSs) with the endoplasmic reticulum (ER), where conserved ATG proteins belonging to the ATG9 lipid scramblase, ATG2 lipid transfer and Atg18/WIPI4 β-propeller families concentrate. Several recent in vivo and in vitro studies have uncovered the relevance of these proteins and MCSs in the lipid supply required for autophagosome formation. Although important conceptual advances have been reached, the functional interrelationship between ATG9, ATG2 and Atg18/WIPI4 proteins at the phagophore-ER MCSs and their role in the phagophore expansion are not completely understood. In this review, we describe the current knowledge about the structure, interactions, localizations, and molecular functions of these proteins, with a particular emphasis on the yeast Saccharomyces cerevisiae and mammalian systems.
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Affiliation(s)
| | - Fulvio Reggiori
- Department of Biomedicine, Aarhus University, Aarhus C, Denmark
- Aarhus Institute of Advanced Studies (AIAS), Aarhus University, Aarhus C, Denmark
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11
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Schuster R, Okamoto K. An overview of the molecular mechanisms of mitophagy in yeast. Biochim Biophys Acta Gen Subj 2022; 1866:130203. [PMID: 35842014 DOI: 10.1016/j.bbagen.2022.130203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 05/27/2022] [Accepted: 07/11/2022] [Indexed: 11/18/2022]
Abstract
Autophagy-dependent selective degradation of excess or damaged mitochondria, termed mitophagy, is a tightly regulated process necessary for mitochondrial quality and quantity control. Mitochondria are highly dynamic and major sites for vital cellular processes such as ATP and iron‑sulfur cluster biogenesis. Due to their pivotal roles for immunity, apoptosis, and aging, the maintenance of mitochondrial function is of utmost importance for cellular homeostasis. In yeast, mitophagy is mediated by the receptor protein Atg32 that is localized to the outer mitochondrial membrane. Upon mitophagy induction, Atg32 expression is transcriptionally upregulated, which leads to its accumulation on the mitochondrial surface and to recruitment of the autophagic machinery via its direct interaction with Atg11 and Atg8. Importantly, post-translational modifications such as phosphorylation further fine-tune the mitophagic response. This review summarizes the current knowledge about mitophagy in yeast and its connection with mitochondrial dynamics and the ubiquitin-proteasome system.
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Affiliation(s)
- Ramona Schuster
- Laboratory of Mitochondrial Dynamics, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Koji Okamoto
- Laboratory of Mitochondrial Dynamics, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
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12
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Majeed ST, Majeed R, Andrabi KI. Expanding the view of the molecular mechanisms of autophagy pathway. J Cell Physiol 2022; 237:3257-3277. [DOI: 10.1002/jcp.30819] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 06/01/2022] [Accepted: 06/07/2022] [Indexed: 01/18/2023]
Affiliation(s)
- Sheikh Tahir Majeed
- Department of Biotechnology Central University of Kashmir Ganderbal Jammu and Kashmir India
- Growth Factor Signaling Laboratory, Department of Biotechnology University of Kashmir Srinagar Jammu and Kashmir India
| | - Rabiya Majeed
- Growth Factor Signaling Laboratory, Department of Biotechnology University of Kashmir Srinagar Jammu and Kashmir India
- Department of Biochemistry University of Kashmir Srinagar Jammu and Kashmir India
| | - Khurshid I. Andrabi
- Growth Factor Signaling Laboratory, Department of Biotechnology University of Kashmir Srinagar Jammu and Kashmir India
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13
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Characterization of Protein-Membrane Interactions in Yeast Autophagy. Cells 2022; 11:cells11121876. [PMID: 35741004 PMCID: PMC9221364 DOI: 10.3390/cells11121876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/03/2022] [Accepted: 06/07/2022] [Indexed: 02/06/2023] Open
Abstract
Cells rely on autophagy to degrade cytosolic material and maintain homeostasis. During autophagy, content to be degraded is encapsulated in double membrane vesicles, termed autophagosomes, which fuse with the yeast vacuole for degradation. This conserved cellular process requires the dynamic rearrangement of membranes. As such, the process of autophagy requires many soluble proteins that bind to membranes to restructure, tether, or facilitate lipid transfer between membranes. Here, we review the methods that have been used to investigate membrane binding by the core autophagy machinery and additional accessory proteins involved in autophagy in yeast. We also review the key experiments demonstrating how each autophagy protein was shown to interact with membranes.
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14
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Hawkins WD, Leary KA, Andhare D, Popelka H, Klionsky DJ, Ragusa MJ. Dimerization-dependent membrane tethering by Atg23 is essential for yeast autophagy. Cell Rep 2022; 39:110702. [PMID: 35443167 PMCID: PMC9097366 DOI: 10.1016/j.celrep.2022.110702] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 02/17/2022] [Accepted: 03/29/2022] [Indexed: 12/24/2022] Open
Abstract
Eukaryotes maintain cellular health through the engulfment and subsequent degradation of intracellular cargo using macroautophagy. The function of Atg23, despite being critical to the efficiency of this process, is unclear due to a lack of biochemical investigations and an absence of any structural information. In this study, we use a combination of in vitro and in vivo methods to show that Atg23 exists primarily as a homodimer, a conformation facilitated by a putative amphipathic helix. We utilize small-angle X-ray scattering to monitor the overall shape of Atg23, revealing that it contains an extended rod-like structure spanning approximately 320 Å. We also demonstrate that Atg23 interacts with membranes directly, primarily through electrostatic interactions, and that these interactions lead to vesicle tethering. Finally, mutation of the hydrophobic face of the putative amphipathic helix completely precludes dimer formation, leading to severely impaired subcellular localization, vesicle tethering, Atg9 binding, and autophagic efficiency.
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Affiliation(s)
- Wayne D Hawkins
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Kelsie A Leary
- Department of Chemistry, Dartmouth College, Hanover, NH 03755, USA
| | - Devika Andhare
- Department of Chemistry, Dartmouth College, Hanover, NH 03755, USA
| | - Hana Popelka
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Daniel J Klionsky
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Michael J Ragusa
- Department of Chemistry, Dartmouth College, Hanover, NH 03755, USA.
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15
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Kang Y, Lin W, Liu Y, Nagy PD. Key tethering function of Atg11 autophagy scaffold protein in formation of virus-induced membrane contact sites during tombusvirus replication. Virology 2022; 572:1-16. [DOI: 10.1016/j.virol.2022.04.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 04/15/2022] [Accepted: 04/25/2022] [Indexed: 01/04/2023]
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16
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Meyer MD, Winzeler J, Taylor SM, Kilgore A, Edicha K, Chitwood C, Spearin Z, Silvia SKNR, Chakraborty R, Smith JE, Kennedy B, Zois C, Cawthon H, Gilruth M, Backues SK. Mapping Critical Residues in ATG11's Coiled-Coil 2 Domain that Block Multiple Interactions and Disrupt Selective Autophagy. Front Cell Dev Biol 2022; 9:775364. [PMID: 35118068 PMCID: PMC8805157 DOI: 10.3389/fcell.2021.775364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 12/23/2021] [Indexed: 11/26/2022] Open
Abstract
Selective autophagy is a conserved subcellular process that maintains the health of eukaryotic cells by targeting damaged or toxic cytoplasmic components to the vacuole/lysosome for degradation. A key player in the initiation of selective autophagy in S. Cerevisiae (baker's yeast) is a large adapter protein called Atg11. Atg11 has multiple predicted coiled-coil domains and intrinsically disordered regions, is known to dimerize, and binds and organizes other essential components of the autophagosome formation machinery, including Atg1 and Atg9. We performed systematic directed mutagenesis on the coiled-coil 2 domain of Atg11 in order to map which residues were required for its structure and function. Using yeast-2-hybrid and coimmunoprecipitation, we found only three residues to be critical: I562, Y565, and I569. Mutation of any of these, but especially Y565, could interfere with Atg11 dimerization and block its interaction with Atg1 and Atg9, thereby inactivating selective autophagy.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | - Steven K. Backues
- Department of Chemistry, Eastern Michigan University, Ypsilanti, MI, United States
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17
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Zheng Q, Duan L, Zhang Y, Li J, Zhang S, Wang H. A dynamically evolving war between autophagy and pathogenic microorganisms. J Zhejiang Univ Sci B 2022; 23:19-41. [PMID: 35029086 PMCID: PMC8758936 DOI: 10.1631/jzus.b2100285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Autophagy is an intracellular degradation process that maintains cellular homeostasis. It is essential for protecting organisms from environmental stress. Autophagy can help the host to eliminate invading pathogens, including bacteria, viruses, fungi, and parasites. However, pathogens have evolved multiple strategies to interfere with autophagic signaling pathways or inhibit the fusion of autophagosomes with lysosomes to form autolysosomes. Moreover, host cell matrix degradation by different types of autophagy can be used for the proliferation and reproduction of pathogens. Thus, determining the roles and mechanisms of autophagy during pathogen infections will promote understanding of the mechanisms of pathogen‒host interactions and provide new strategies for the treatment of infectious diseases.
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Affiliation(s)
- Qianqian Zheng
- Henan Key Laboratory of Immunology and Targeted Drugs, School of Laboratory Medicine, Xinxiang Medical University, Xinxiang 453003, China.,Henan Collaborative Innovation Center of Molecular Diagnosis and Laboratory Medicine, Xinxiang Medical University, Xinxiang 453003, China
| | - Liangwei Duan
- Henan Key Laboratory of Immunology and Targeted Drugs, School of Laboratory Medicine, Xinxiang Medical University, Xinxiang 453003, China.,Henan Collaborative Innovation Center of Molecular Diagnosis and Laboratory Medicine, Xinxiang Medical University, Xinxiang 453003, China
| | - Yang Zhang
- Henan Key Laboratory of Immunology and Targeted Drugs, School of Laboratory Medicine, Xinxiang Medical University, Xinxiang 453003, China.,Henan Collaborative Innovation Center of Molecular Diagnosis and Laboratory Medicine, Xinxiang Medical University, Xinxiang 453003, China
| | - Jiaoyang Li
- Henan Key Laboratory of Immunology and Targeted Drugs, School of Laboratory Medicine, Xinxiang Medical University, Xinxiang 453003, China.,Henan Collaborative Innovation Center of Molecular Diagnosis and Laboratory Medicine, Xinxiang Medical University, Xinxiang 453003, China
| | - Shiyu Zhang
- Henan Key Laboratory of Immunology and Targeted Drugs, School of Laboratory Medicine, Xinxiang Medical University, Xinxiang 453003, China.,Henan Collaborative Innovation Center of Molecular Diagnosis and Laboratory Medicine, Xinxiang Medical University, Xinxiang 453003, China
| | - Hui Wang
- Henan Key Laboratory of Immunology and Targeted Drugs, School of Laboratory Medicine, Xinxiang Medical University, Xinxiang 453003, China. .,Henan Collaborative Innovation Center of Molecular Diagnosis and Laboratory Medicine, Xinxiang Medical University, Xinxiang 453003, China.
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18
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Application of Metabolomics in the Study of Starvation-Induced Autophagy in Saccharomyces cerevisiae: A Scoping Review. J Fungi (Basel) 2021; 7:jof7110987. [PMID: 34829274 PMCID: PMC8619235 DOI: 10.3390/jof7110987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 11/15/2021] [Accepted: 11/16/2021] [Indexed: 11/18/2022] Open
Abstract
This scoping review is aimed at the application of the metabolomics platform to dissect key metabolites and their intermediates to observe the regulatory mechanisms of starvation-induced autophagy in Saccharomyces cerevisiae. Four research papers were shortlisted in this review following the inclusion and exclusion criteria. We observed a commonly shared pathway undertaken by S. cerevisiae under nutritional stress. Targeted and untargeted metabolomics was applied in either of these studies using varying platforms resulting in the annotation of several different observable metabolites. We saw a commonly shared pathway undertaken by S. cerevisiae under nutritional stress. Following nitrogen starvation, the concentration of cellular nucleosides was altered as a result of autophagic RNA degradation. Additionally, it is also found that autophagy replenishes amino acid pools to sustain macromolecule synthesis. Furthermore, in glucose starvation, nucleosides were broken down into carbonaceous metabolites that are being funneled into the non-oxidative pentose phosphate pathway. The ribose salvage allows for the survival of starved yeast. Moreover, acute glucose starvation showed autophagy to be involved in maintaining ATP/energy levels. We highlighted the practicality of metabolomics as a tool to better understand the underlying mechanisms involved to maintain homeostasis by recycling degradative products to ensure the survival of S. cerevisiae under starvation. The application of metabolomics has extended the scope of autophagy and provided newer intervention targets against cancer as well as neurodegenerative diseases in which autophagy is implicated.
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19
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Hanley SE, Willis SD, Cooper KF. Snx4-assisted vacuolar targeting of transcription factors defines a new autophagy pathway for controlling ATG expression. Autophagy 2021; 17:3547-3565. [PMID: 33678121 PMCID: PMC8632336 DOI: 10.1080/15548627.2021.1877934] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 01/14/2021] [Indexed: 12/18/2022] Open
Abstract
Autophagy, in part, is controlled by the repression and activation of autophagy-related (ATG) genes. Here, we describe a new selective autophagy pathway that targets functional transcriptional regulators to control their activity. This pathway is activated in response to nitrogen starvation and recycles transcriptional activators (Msn2 and Rim15) and a repressor (Ssn2/Med13) of ATG expression. Further analysis of Ssn2/Med13 vacuolar proteolysis revealed that this pathway utilizes the core autophagic machinery. However, it is independent of known nucleophagy mechanisms, receptor proteins, and the scaffold protein Atg11. Instead, Ssn2/Med13 exits the nucleus through the nuclear pore complex (NPC) and associates with the cytoplasmic nucleoporin Gle1, a member of the RNA remodeling complex. Dbp5 and Nup159, that act in concert with Gle1, are also required for Ssn2/Med13 clearance. Ssn2/Med13 is retrieved from the nuclear periphery and degraded by Atg17-initiated phagophores anchored to the vacuole. Efficient transfer to phagophores depends on the sorting nexin heterodimer Snx4/Atg24-Atg20, which binds to Atg17, and relocates to the perinucleus following nitrogen starvation. To conclude, this pathway defines a previously undescribed autophagy mechanism that targets select transcriptional regulators for rapid vacuolar proteolysis, utilizing the RNA remodeling complex, the sorting nexin heterodimer Snx4-Atg20, Atg17, and the core autophagic machinery. It is physiologically relevant as this Snx4-assisted vacuolar targeting pathway permits cells to fine-tune the autophagic response by controlling the turnover of both positive and negative regulators of ATG transcription.Abbreviations: AIM: Atg8 interacting motif; ATG: autophagy-related; CKM: CDK8 kinase module; IDR: intrinsically disordered region; IP6: phosphoinositide inositol hexaphosphate; NPC: nuclear pore complex; PAS: phagophore assembly site; UPS: ubiquitin-proteasomal system.
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Affiliation(s)
- Sara E. Hanley
- Department of Molecular Biology, Graduate School of Biomedical Sciences, Rowan University, Stratford, NJ, USA
| | - Stephen D. Willis
- Department of Molecular Biology, Graduate School of Biomedical Sciences, Rowan University, Stratford, NJ, USA
| | - Katrina F. Cooper
- Department of Molecular Biology, Graduate School of Biomedical Sciences, Rowan University, Stratford, NJ, USA
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20
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Huang YJ, Klionsky DJ. Yeast mitophagy: Unanswered questions. Biochim Biophys Acta Gen Subj 2021; 1865:129932. [PMID: 34022298 PMCID: PMC8205991 DOI: 10.1016/j.bbagen.2021.129932] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 05/13/2021] [Accepted: 05/17/2021] [Indexed: 01/18/2023]
Abstract
Superfluous and damaged mitochondria need to be efficiently repaired or removed. Mitophagy is a selective type of autophagy that can engulf a portion of mitochondria within a double-membrane structure, called a mitophagosome, and deliver it to the vacuole for degradation. Mitophagy has significant physiological functions from yeast to human, and recent advances in yeast mitophagy shed light on the molecular mechanisms of mitophagy, especially the regulation of mitophagy induction. This review summarizes our current knowledge about yeast mitophagy and considers several unsolved questions, with a particular focus on Saccharomyces cerevisiae.
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Affiliation(s)
- Yuxiang J Huang
- Life Sciences Institute and Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Daniel J Klionsky
- Life Sciences Institute and Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.
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21
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Gómez-Sánchez R, Tooze SA, Reggiori F. Membrane supply and remodeling during autophagosome biogenesis. Curr Opin Cell Biol 2021; 71:112-119. [PMID: 33930785 DOI: 10.1016/j.ceb.2021.02.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/17/2021] [Accepted: 02/04/2021] [Indexed: 12/17/2022]
Abstract
The de novo generation of double-membrane autophagosomes is the hallmark of autophagy. The initial membranous precursor cisterna, the phagophore, is very likely generated by the fusion of vesicles and acts as a membrane seed for the subsequent expansion into an autophagosome. This latter step requires a massive convoy of lipids into the phagophore. In this review, we present recent advances in our understanding of the intracellular membrane sources and lipid delivery mechanisms, which principally rely on vesicular transport and membrane contact sites that contribute to autophagosome biogenesis. In this context, we discuss lipid biosynthesis and lipid remodeling events that play a crucial role in both phagophore nucleation and expansion.
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Affiliation(s)
- Rubén Gómez-Sánchez
- Department of Biomedical Sciences of Cells & Systems, University of Groningen, University Medical Center Groningen, A. Deusinglaan 1, 9713 AV Groningen, the Netherlands
| | - Sharon A Tooze
- Molecular Cell Biology of Autophagy, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, United Kingdom
| | - Fulvio Reggiori
- Department of Biomedical Sciences of Cells & Systems, University of Groningen, University Medical Center Groningen, A. Deusinglaan 1, 9713 AV Groningen, the Netherlands.
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22
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Melia TJ, Lystad AH, Simonsen A. Autophagosome biogenesis: From membrane growth to closure. J Cell Biol 2021; 219:151729. [PMID: 32357219 PMCID: PMC7265318 DOI: 10.1083/jcb.202002085] [Citation(s) in RCA: 164] [Impact Index Per Article: 54.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 04/04/2020] [Accepted: 04/06/2020] [Indexed: 12/14/2022] Open
Abstract
Autophagosome biogenesis involves de novo formation of a membrane that elongates to sequester cytoplasmic cargo and closes to form a double-membrane vesicle (an autophagosome). This process has remained enigmatic since its initial discovery >50 yr ago, but our understanding of the mechanisms involved in autophagosome biogenesis has increased substantially during the last 20 yr. Several key questions do remain open, however, including, What determines the site of autophagosome nucleation? What is the origin and lipid composition of the autophagosome membrane? How is cargo sequestration regulated under nonselective and selective types of autophagy? This review provides key insight into the core molecular mechanisms underlying autophagosome biogenesis, with a specific emphasis on membrane modeling events, and highlights recent conceptual advances in the field.
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Affiliation(s)
- Thomas J Melia
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT
| | - Alf H Lystad
- Department of Molecular Medicine, Institute of Basic Medical Sciences and Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Anne Simonsen
- Department of Molecular Medicine, Institute of Basic Medical Sciences and Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
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23
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Hanley SE, Cooper KF. Sorting Nexins in Protein Homeostasis. Cells 2020; 10:cells10010017. [PMID: 33374212 PMCID: PMC7823608 DOI: 10.3390/cells10010017] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 12/15/2020] [Accepted: 12/18/2020] [Indexed: 12/11/2022] Open
Abstract
Protein homeostasis is maintained by removing misfolded, damaged, or excess proteins and damaged organelles from the cell by three major pathways; the ubiquitin-proteasome system, the autophagy-lysosomal pathway, and the endo-lysosomal pathway. The requirement for ubiquitin provides a link between all three pathways. Sorting nexins are a highly conserved and diverse family of membrane-associated proteins that not only traffic proteins throughout the cells but also provide a second common thread between protein homeostasis pathways. In this review, we will discuss the connections between sorting nexins, ubiquitin, and the interconnected roles they play in maintaining protein quality control mechanisms. Underlying their importance, genetic defects in sorting nexins are linked with a variety of human diseases including neurodegenerative, cardiovascular diseases, viral infections, and cancer. This serves to emphasize the critical roles sorting nexins play in many aspects of cellular function.
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24
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Wilfling F, Lee CW, Erdmann PS, Zheng Y, Sherpa D, Jentsch S, Pfander B, Schulman BA, Baumeister W. A Selective Autophagy Pathway for Phase-Separated Endocytic Protein Deposits. Mol Cell 2020; 80:764-778.e7. [PMID: 33207182 PMCID: PMC7721475 DOI: 10.1016/j.molcel.2020.10.030] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 09/20/2020] [Accepted: 10/21/2020] [Indexed: 12/14/2022]
Abstract
Autophagy eliminates cytoplasmic content selected by autophagy receptors, which link cargo to the membrane-bound autophagosomal ubiquitin-like protein Atg8/LC3. Here, we report a selective autophagy pathway for protein condensates formed by endocytic proteins in yeast. In this pathway, the endocytic protein Ede1 functions as a selective autophagy receptor. Distinct domains within Ede1 bind Atg8 and mediate phase separation into condensates. Both properties are necessary for an Ede1-dependent autophagy pathway for endocytic proteins, which differs from regular endocytosis and does not involve other known selective autophagy receptors but requires the core autophagy machinery. Cryo-electron tomography of Ede1-containing condensates, at the plasma membrane and in autophagic bodies, shows a phase-separated compartment at the beginning and end of the Ede1-mediated selective autophagy route. Our data suggest a model for autophagic degradation of macromolecular protein complexes by the action of intrinsic autophagy receptors.
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Affiliation(s)
- Florian Wilfling
- Molecular Cell Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany; Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany; Molecular Machines and Signaling, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.
| | - Chia-Wei Lee
- Molecular Cell Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany; Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Philipp S Erdmann
- Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.
| | - Yumei Zheng
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA; Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Dawafuti Sherpa
- Molecular Machines and Signaling, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Stefan Jentsch
- Molecular Cell Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Boris Pfander
- DNA Replication and Genome Integrity, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Brenda A Schulman
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA; Molecular Machines and Signaling, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Wolfgang Baumeister
- Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.
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25
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In vitro reconstitution of autophagic processes. Biochem Soc Trans 2020; 48:2003-2014. [PMID: 32897375 DOI: 10.1042/bst20200130] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 08/12/2020] [Accepted: 08/13/2020] [Indexed: 11/17/2022]
Abstract
Autophagy is a lysosomal degradation system that involves de novo autophagosome formation. A lot of factors are involved in autophagosome formation, including dozens of Atg proteins that form supramolecular complexes, membrane structures including vesicles and organelles, and even membraneless organelles. Because these diverse higher-order structural components cooperate to mediate de novo formation of autophagosomes, it is too complicated to be elaborated only by cell biological approaches. Recent trials to regenerate each step of this phenomenon in vitro have started to elaborate on the molecular mechanisms of such a complicated process by simplification. In this review article, we outline the in vitro reconstitution trials in autophagosome formation, mainly focusing on the reports in the past few years and discussing the molecular mechanisms of autophagosome formation by comparing in vitro and in vivo observations.
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26
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Cheung YWS, Nam SE, Yip CK. Recent Advances in Single-Particle Electron Microscopic Analysis of Autophagy Degradation Machinery. Int J Mol Sci 2020; 21:E8051. [PMID: 33126766 PMCID: PMC7663694 DOI: 10.3390/ijms21218051] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 10/25/2020] [Accepted: 10/25/2020] [Indexed: 12/31/2022] Open
Abstract
Macroautophagy (also known as autophagy) is a major pathway for selective degradation of misfolded/aggregated proteins and damaged organelles and non-selective degradation of cytoplasmic constituents for the generation of power during nutrient deprivation. The multi-step degradation process, from sequestering cytoplasmic cargo into the double-membrane vesicle termed autophagosome to the delivery of the autophagosome to the lysosome or lytic vacuole for breakdown, is mediated by the core autophagy machinery composed of multiple Atg proteins, as well as the divergent sequence family of selective autophagy receptors. Single-particle electron microscopy (EM) is a molecular imaging approach that has become an increasingly important tool in the structural characterization of proteins and macromolecular complexes. This article summarizes the contributions single-particle EM have made in advancing our understanding of the core autophagy machinery and selective autophagy receptors. We also discuss current technical challenges and roadblocks, as well as look into the future of single-particle EM in autophagy research.
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Affiliation(s)
| | | | - Calvin K. Yip
- Life Sciences Institute, Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada; (Y.W.S.C.); (S.-E.N.)
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27
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Gao J, Kurre R, Rose J, Walter S, Fröhlich F, Piehler J, Reggiori F, Ungermann C. Function of the SNARE Ykt6 on autophagosomes requires the Dsl1 complex and the Atg1 kinase complex. EMBO Rep 2020; 21:e50733. [PMID: 33025734 PMCID: PMC7726795 DOI: 10.15252/embr.202050733] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 09/04/2020] [Accepted: 09/14/2020] [Indexed: 12/11/2022] Open
Abstract
The mechanism and regulation of fusion between autophagosomes and lysosomes/vacuoles are still only partially understood in both yeast and mammals. In yeast, this fusion step requires SNARE proteins, the homotypic vacuole fusion and protein sorting (HOPS) tethering complex, the RAB7 GTPase Ypt7, and its guanine nucleotide exchange factor (GEF) Mon1‐Ccz1. We and others recently identified Ykt6 as the autophagosomal SNARE protein. However, it has not been resolved when and how lipid‐anchored Ykt6 is recruited onto autophagosomes. Here, we show that Ykt6 is recruited at an early stage of the formation of these carriers through a mechanism that depends on endoplasmic reticulum (ER)‐resident Dsl1 complex and COPII‐coated vesicles. Importantly, Ykt6 activity on autophagosomes is regulated by the Atg1 kinase complex, which inhibits Ykt6 through direct phosphorylation. Thus, our findings indicate that the Ykt6 pool on autophagosomal membranes is kept inactive by Atg1 phosphorylation, and once an autophagosome is ready to fuse with vacuole, Ykt6 dephosphorylation allows its engagement in the fusion event.
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Affiliation(s)
- Jieqiong Gao
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, Osnabrück, Germany
| | - Rainer Kurre
- Center of Cellular Nanoanalytics Osnabrück (CellNanOs), University of Osnabrück, Osnabrück, Germany.,Center of Cellular Nanoanalytics, Integrated Bioimaging Facility, University of Osnabrück, Osnabrück, Germany
| | - Jaqueline Rose
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, Osnabrück, Germany
| | - Stefan Walter
- Center of Cellular Nanoanalytics Osnabrück (CellNanOs), University of Osnabrück, Osnabrück, Germany
| | - Florian Fröhlich
- Department of Biology/Chemistry, Molecular Membrane Biology Group, University of Osnabrück, Osnabrück, Germany
| | - Jacob Piehler
- Center of Cellular Nanoanalytics Osnabrück (CellNanOs), University of Osnabrück, Osnabrück, Germany.,Center of Cellular Nanoanalytics, Integrated Bioimaging Facility, University of Osnabrück, Osnabrück, Germany.,Department of Biology/Chemistry, Biophysics Section, University of Osnabrück, Osnabrück, Germany
| | - Fulvio Reggiori
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Christian Ungermann
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, Osnabrück, Germany.,Center of Cellular Nanoanalytics Osnabrück (CellNanOs), University of Osnabrück, Osnabrück, Germany
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28
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Margolis HK, Katzenell S, Leary KA, Ragusa MJ. The Third Coiled Coil Domain of Atg11 Is Required for Shaping Mitophagy Initiation Sites. J Mol Biol 2020; 432:5752-5764. [PMID: 32896530 DOI: 10.1016/j.jmb.2020.08.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 08/27/2020] [Accepted: 08/28/2020] [Indexed: 11/26/2022]
Abstract
Selective autophagy is the capture of specific cytosolic contents in double-membrane vesicles that subsequently fuse with the vacuole or lysosome, thereby delivering cargo for degradation. Selective autophagy receptors (SARs) mark the cargo for degradation and, in yeast, recruit Atg11, the scaffolding protein for selective autophagy initiation. The mitochondrial protein Atg32 is the yeast SAR that mediates mitophagy, the selective autophagic capture of mitochondria. Atg11-Atg32 interactions concentrate Atg32 into puncta that are thought to represent sites of mitophagy initiation. However, it is unclear how Atg11 concentrates Atg32 to generate mitophagy initiation sites. We show here that the coiled coil 3 (CC3) domain of Atg11 is required for concentrating Atg32 into puncta. We determined the structure of the majority of the CC3, demonstrating that the CC3 forms a parallel homodimer whose dimer interface is formed by a small number of hydrophobic residues. We further show that the CC3 interface is not required for Atg11 dimerization but is required for shaping Atg32 into functional mitophagy initiation sites and for delivery of mitochondria to the vacuole. Our findings suggest that Atg11 self-interactions help concentrate SARs as a necessary precondition for cargo capture.
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Affiliation(s)
| | - Sarah Katzenell
- Department of Chemistry, Dartmouth College, Hanover, NH 03755, USA
| | - Kelsie A Leary
- Department of Chemistry, Dartmouth College, Hanover, NH 03755, USA
| | - Michael J Ragusa
- Department of Chemistry, Dartmouth College, Hanover, NH 03755, USA; Department of Biochemistry and Cell Biology, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA.
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Sawa-Makarska J, Baumann V, Coudevylle N, von Bülow S, Nogellova V, Abert C, Schuschnig M, Graef M, Hummer G, Martens S. Reconstitution of autophagosome nucleation defines Atg9 vesicles as seeds for membrane formation. Science 2020; 369:eaaz7714. [PMID: 32883836 PMCID: PMC7610778 DOI: 10.1126/science.aaz7714] [Citation(s) in RCA: 154] [Impact Index Per Article: 38.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 05/16/2020] [Accepted: 07/06/2020] [Indexed: 12/15/2022]
Abstract
Autophagosomes form de novo in a manner that is incompletely understood. Particularly enigmatic are autophagy-related protein 9 (Atg9)-containing vesicles that are required for autophagy machinery assembly but do not supply the bulk of the autophagosomal membrane. In this study, we reconstituted autophagosome nucleation using recombinant components from yeast. We found that Atg9 proteoliposomes first recruited the phosphatidylinositol 3-phosphate kinase complex, followed by Atg21, the Atg2-Atg18 lipid transfer complex, and the E3-like Atg12-Atg5-Atg16 complex, which promoted Atg8 lipidation. Furthermore, we found that Atg2 could transfer lipids for Atg8 lipidation. In selective autophagy, these reactions could potentially be coupled to the cargo via the Atg19-Atg11-Atg9 interactions. We thus propose that Atg9 vesicles form seeds that establish membrane contact sites to initiate lipid transfer from compartments such as the endoplasmic reticulum.
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Affiliation(s)
- Justyna Sawa-Makarska
- Department of Biochemistry and Cell Biology, Max Perutz Labs, University of Vienna, 1030 Vienna, Austria.
| | - Verena Baumann
- Department of Biochemistry and Cell Biology, Max Perutz Labs, University of Vienna, 1030 Vienna, Austria
| | - Nicolas Coudevylle
- Department of Biochemistry and Cell Biology, Max Perutz Labs, University of Vienna, 1030 Vienna, Austria
| | - Sören von Bülow
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Veronika Nogellova
- Department of Biochemistry and Cell Biology, Max Perutz Labs, University of Vienna, 1030 Vienna, Austria
| | - Christine Abert
- Department of Biochemistry and Cell Biology, Max Perutz Labs, University of Vienna, 1030 Vienna, Austria
| | - Martina Schuschnig
- Department of Biochemistry and Cell Biology, Max Perutz Labs, University of Vienna, 1030 Vienna, Austria
| | - Martin Graef
- Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50931 Cologne, Germany
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
- Institute for Biophysics, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
| | - Sascha Martens
- Department of Biochemistry and Cell Biology, Max Perutz Labs, University of Vienna, 1030 Vienna, Austria.
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30
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The Roles of Ubiquitin in Mediating Autophagy. Cells 2020; 9:cells9092025. [PMID: 32887506 PMCID: PMC7564124 DOI: 10.3390/cells9092025] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 08/25/2020] [Accepted: 08/28/2020] [Indexed: 12/20/2022] Open
Abstract
Ubiquitination, the post-translational modification essential for various intracellular processes, is implicated in multiple aspects of autophagy, the major lysosome/vacuole-dependent degradation pathway. The autophagy machinery adopted the structural architecture of ubiquitin and employs two ubiquitin-like protein conjugation systems for autophagosome biogenesis. Ubiquitin chains that are attached as labels to protein aggregates or subcellular organelles confer selectivity, allowing autophagy receptors to simultaneously bind ubiquitinated cargos and autophagy-specific ubiquitin-like modifiers (Atg8-family proteins). Moreover, there is tremendous crosstalk between autophagy and the ubiquitin-proteasome system. Ubiquitination of autophagy-related proteins or regulatory components plays significant roles in the precise control of the autophagy pathway. In this review, we summarize and discuss the molecular mechanisms and functions of ubiquitin and ubiquitination, in the process and regulation of autophagy.
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31
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Abstract
Autophagy is an intracellular degradation pathway targeting organelles and macromolecules, thereby regulating various cellular functions. Phosphorylation is a key posttranscriptional protein modification implicated in the regulation of biological function including autophagy. Under asynchronous conditions, autophagy activity is predominantly suppressed by mechanistic target of rapamycin (mTOR) kinase, but whether autophagy-related genes (ATG) proteins are phosphorylated differentially throughout the sequential phases of the cell cycle remains unclear. In this issue, Li and colleagues report that cyclin-dependent kinase 1 (CDK1) phosphorylates the ULK complex during mitosis. This phosphorylation induces autophagy and, surprisingly, is shown to drive cell cycle progression. This work reveals a yet-unappreciated role for autophagy in cell cycle progression and enhances our understanding of the specific phase-dependent autophagy regulation during cellular growth and proliferation.
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Affiliation(s)
- Akinori Yamasaki
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
| | - Yui Jin
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
- Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
| | - Yoshinori Ohsumi
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
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32
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Tang BL. Syntaxin 16's Newly Deciphered Roles in Autophagy. Cells 2019; 8:cells8121655. [PMID: 31861136 PMCID: PMC6953085 DOI: 10.3390/cells8121655] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 12/05/2019] [Accepted: 12/06/2019] [Indexed: 12/16/2022] Open
Abstract
Syntaxin 16, a Qa-SNARE (soluble N-ethylmaleimide-sensitive factor activating protein receptor), is involved in a number of membrane-trafficking activities, particularly transport processes at the trans-Golgi network (TGN). Recent works have now implicated syntaxin 16 in the autophagy process. In fact, syntaxin 16 appears to have dual roles, firstly in facilitating the transport of ATG9a-containing vesicles to growing autophagosomes, and secondly in autolysosome formation. The former involves a putative SNARE complex between syntaxin 16, VAMP7 and SNAP-47. The latter occurs via syntaxin 16’s recruitment by Atg8/LC3/GABARAP family proteins to autophagosomes and endo-lysosomes, where syntaxin 16 may act in a manner that bears functional redundancy with the canonical autophagosome Qa-SNARE syntaxin 17. Here, I discuss these recent findings and speculate on the mechanistic aspects of syntaxin 16’s newly found role in autophagy.
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Affiliation(s)
- Bor Luen Tang
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117596, Singapore; ; Tel.: +65-6516-1040
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 119077, Singapore
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