1
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Gubas A, Attridge E, Jefferies HB, Nishimura T, Razi M, Kunzelmann S, Gilad Y, Mercer TJ, Wilson MM, Kimchi A, Tooze SA. WIPI2b recruitment to phagophores and ATG16L1 binding are regulated by ULK1 phosphorylation. EMBO Rep 2024; 25:3789-3811. [PMID: 39152217 PMCID: PMC11387628 DOI: 10.1038/s44319-024-00215-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 06/21/2024] [Accepted: 07/04/2024] [Indexed: 08/19/2024] Open
Abstract
One of the key events in autophagy is the formation of a double-membrane phagophore, and many regulatory mechanisms underpinning this remain under investigation. WIPI2b is among the first proteins to be recruited to the phagophore and is essential for stimulating autophagy flux by recruiting the ATG12-ATG5-ATG16L1 complex, driving LC3 and GABARAP lipidation. Here, we set out to investigate how WIPI2b function is regulated by phosphorylation. We studied two phosphorylation sites on WIPI2b, S68 and S284. Phosphorylation at these sites plays distinct roles, regulating WIPI2b's association with ATG16L1 and the phagophore, respectively. We confirm WIPI2b is a novel ULK1 substrate, validated by the detection of endogenous phosphorylation at S284. Notably, S284 is situated within an 18-amino acid stretch, which, when in contact with liposomes, forms an amphipathic helix. Phosphorylation at S284 disrupts the formation of the amphipathic helix, hindering the association of WIPI2b with membranes and autophagosome formation. Understanding these intricacies in the regulatory mechanisms governing WIPI2b's association with its interacting partners and membranes, holds the potential to shed light on these complex processes, integral to phagophore biogenesis.
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Affiliation(s)
- Andrea Gubas
- Molecular Cell Biology of Autophagy, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
- Muscular Dystrophy UK, London, SE1 8QD, UK
| | - Eleanor Attridge
- Molecular Cell Biology of Autophagy, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Harold Bj Jefferies
- Molecular Cell Biology of Autophagy, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Taki Nishimura
- Department of Biochemistry and Molecular Biology, Graduate School and Faculty of Medicine, The University of Tokyo, Tokyo, Japan
- PRESTO, Japan Science and Technology Agency, Chiyoda-ku, Tokyo, Japan
| | - Minoo Razi
- Molecular Cell Biology of Autophagy, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Simone Kunzelmann
- Structural Biology Science Technology Platform, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Yuval Gilad
- The Weizmann Institute of Science, Rehovot, Israel
| | | | | | - Adi Kimchi
- The Weizmann Institute of Science, Rehovot, Israel
| | - Sharon A Tooze
- Molecular Cell Biology of Autophagy, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.
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2
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Gopaldass N, Mayer A. PROPPINs and membrane fission in the endo-lysosomal system. Biochem Soc Trans 2024; 52:1233-1241. [PMID: 38747700 DOI: 10.1042/bst20230897] [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: 02/27/2024] [Revised: 04/21/2024] [Accepted: 04/22/2024] [Indexed: 06/27/2024]
Abstract
PROPPINs constitute a conserved protein family with multiple members being expressed in many eukaryotes. PROPPINs have mainly been investigated for their role in autophagy, where they co-operate with several core factors for autophagosome formation. Recently, novel functions of these proteins on endo-lysosomal compartments have emerged. PROPPINs support the division of these organelles and the formation of tubulo-vesicular cargo carriers that mediate protein exit from them, such as those generated by the Retromer coat. In both cases, PROPPINs provide membrane fission activity. Integrating information from yeast and human cells this review summarizes the most important molecular features that allow these proteins to facilitate membrane fission and thus provide a critical element to endo-lysosomal protein traffic.
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Affiliation(s)
- Navin Gopaldass
- Department of Immunobiology, University of Lausanne, Epalinges, Switzerland
| | - Andreas Mayer
- Department of Immunobiology, University of Lausanne, Epalinges, Switzerland
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3
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Yagyu M, Yoshimoto K. New insights into plant autophagy: molecular mechanisms and roles in development and stress responses. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:1234-1251. [PMID: 37978884 DOI: 10.1093/jxb/erad459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2023] [Accepted: 11/17/2023] [Indexed: 11/19/2023]
Abstract
Autophagy is an evolutionarily conserved eukaryotic intracellular degradation process. Although the molecular mechanisms of plant autophagy share similarities with those in yeast and mammals, certain unique mechanisms have been identified. Recent studies have highlighted the importance of autophagy during vegetative growth stages as well as in plant-specific developmental processes, such as seed development, germination, flowering, and somatic reprogramming. Autophagy enables plants to adapt to and manage severe environmental conditions, such as nutrient starvation, high-intensity light stress, and heat stress, leading to intracellular remodeling and physiological changes in response to stress. In the past, plant autophagy research lagged behind similar studies in yeast and mammals; however, recent advances have greatly expanded our understanding of plant-specific autophagy mechanisms and functions. This review summarizes current knowledge and latest research findings on the mechanisms and roles of plant autophagy with the objective of improving our understanding of this vital process in plants.
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Affiliation(s)
- Mako Yagyu
- Department of Life Sciences, School of Agriculture, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa, 214-8571, Japan
- Life Sciences Program, Graduate School of Agriculture, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa, 214-8571, Japan
| | - Kohki Yoshimoto
- Department of Life Sciences, School of Agriculture, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa, 214-8571, Japan
- Life Sciences Program, Graduate School of Agriculture, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa, 214-8571, Japan
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4
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Kotani T, Yasuda Y, Nakatogawa H. Molecular Mechanism of Autophagy, Cytoplasmic Zoning by Lipid Membranes. J Biochem 2024; 175:155-165. [PMID: 37983716 DOI: 10.1093/jb/mvad099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 11/02/2023] [Accepted: 11/06/2023] [Indexed: 11/22/2023] Open
Abstract
Autophagy is a highly conserved intracellular degradation mechanism. The most distinctive feature of autophagy is the formation of double-membrane structures called autophagosomes, which compartmentalize portions of the cytoplasm. The outer membrane of the autophagosome fuses with the vacuolar/lysosomal membrane, leading to the degradation of the contents of the autophagosome. Approximately 30 years have passed since the identification of autophagy-related (ATG) genes and Atg proteins essential for autophagosome formation, and the primary functions of these Atg proteins have been elucidated. These achievements have significantly advanced our understanding of the mechanism of autophagosome formation. This article summarizes our current knowledge on how the autophagosome precursor is generated, and how the membrane expands and seals to complete the autophagosome.
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Affiliation(s)
- Tetsuya Kotani
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, S2-14 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8501, Japan
| | - Yuri Yasuda
- School of Life Science and Technology, Tokyo Institute of Technology, S2-14 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8501, Japan
| | - Hitoshi Nakatogawa
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, S2-14 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8501, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, S2-14 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8501, Japan
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5
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Noda NN. Structural view on autophagosome formation. FEBS Lett 2024; 598:84-106. [PMID: 37758522 DOI: 10.1002/1873-3468.14742] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Revised: 09/02/2023] [Accepted: 09/04/2023] [Indexed: 09/29/2023]
Abstract
Autophagy is a conserved intracellular degradation system in eukaryotes, involving the sequestration of degradation targets into autophagosomes, which are subsequently delivered to lysosomes (or vacuoles in yeasts and plants) for degradation. In budding yeast, starvation-induced autophagosome formation relies on approximately 20 core Atg proteins, grouped into six functional categories: the Atg1/ULK complex, the phosphatidylinositol-3 kinase complex, the Atg9 transmembrane protein, the Atg2-Atg18/WIPI complex, the Atg8 lipidation system, and the Atg12-Atg5 conjugation system. Additionally, selective autophagy requires cargo receptors and other factors, including a fission factor, for specific sequestration. This review covers the 30-year history of structural studies on core Atg proteins and factors involved in selective autophagy, examining X-ray crystallography, NMR, and cryo-EM techniques. The molecular mechanisms of autophagy are explored based on protein structures, and future directions in the structural biology of autophagy are discussed, considering the advancements in the era of AlphaFold.
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Affiliation(s)
- Nobuo N Noda
- Institute for Genetic Medicine, Hokkaido University, Sapporo, Japan
- Institute of Microbial Chemistry (BIKAKEN), Tokyo, Japan
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6
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Luo M, Law KC, He Y, Chung KK, Po MK, Feng L, Chung KP, Gao C, Zhuang X, Jiang L. Arabidopsis AUTOPHAGY-RELATED2 is essential for ATG18a and ATG9 trafficking during autophagosome closure. PLANT PHYSIOLOGY 2023; 193:304-321. [PMID: 37195145 DOI: 10.1093/plphys/kiad287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 04/25/2023] [Accepted: 04/27/2023] [Indexed: 05/18/2023]
Abstract
As a fundamental metabolic pathway, autophagy plays important roles in plant growth and development, particularly under stress conditions. A set of autophagy-related (ATG) proteins is recruited for the formation of a double-membrane autophagosome. Among them, the essential roles of ATG2, ATG18, and ATG9 have been well established in plant autophagy via genetic analysis; however, the underlying molecular mechanism for ATG2 in plant autophagosome formation remains poorly understood. In this study, we focused on the specific role of ATG2 in the trafficking of ATG18a and ATG9 during autophagy in Arabidopsis (Arabidopsis thaliana). Under normal conditions, YFP-ATG18a proteins are partially localized on late endosomes and translocated to ATG8e-labeled autophagosomes upon autophagic induction. Real-time imaging analysis revealed sequential recruitment of ATG18a on the phagophore membrane, showing that ATG18a specifically decorated the closing edges and finally disassociated from the completed autophagosome. However, in the absence of ATG2, most of the YFP-ATG18a proteins are arrested on autophagosomal membranes. Ultrastructural and 3D tomography analysis showed that unclosed autophagosome structures are accumulated in the atg2 mutant, displaying direct connections with the endoplasmic reticulum membrane and vesicular structures. Dynamic analysis of ATG9 vesicles suggested that ATG2 depletion also affects the association between ATG9 vesicles and the autophagosomal membrane. Furthermore, using interaction and recruitment analysis, we mapped the interaction relationship between ATG2 and ATG18a, implying a possible role of ATG18a in recruiting ATG2 and ATG9 to the membrane. Our findings unveil a specific role of ATG2 in coordinating ATG18a and ATG9 trafficking to mediate autophagosome closure in Arabidopsis.
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Affiliation(s)
- Mengqian Luo
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Kai Ching Law
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Yilin He
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Ka Kit Chung
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Muk Kuen Po
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Lanlan Feng
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Kin Pan Chung
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Caiji Gao
- Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Xiaohong Zhuang
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Liwen Jiang
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
- CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen 518057, China
- Institute of Plant Molecular Biology and Agricultural Biotechnology, The Chinese University of Hong Kong, Hong Kong, China
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7
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Marquardt L, Thumm M. Autophagic and non-autophagic functions of the Saccharomyces cerevisiae PROPPINs Atg18, Atg21 and Hsv2. Biol Chem 2023; 404:813-819. [PMID: 37139661 DOI: 10.1515/hsz-2023-0126] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 04/17/2023] [Indexed: 05/05/2023]
Abstract
Atg18, Atg21 and Hsv2 are homologous β-propeller proteins binding to PI3P and PI(3,5)P2. Atg18 is thought to organize lipid transferring protein complexes at contact sites of the growing autophagosome (phagophore) with both the ER and the vacuole. Atg21 is restricted to the vacuole phagophore contact, where it organizes part of the Atg8-lipidation machinery. The role of Hsv2 is less understood, it partly affects micronucleophagy. Atg18 is further involved in regulation of PI(3,5)P2 synthesis. Recently, a novel Atg18-retromer complex and its role in vacuole homeostasis and membrane fission was uncovered.
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Affiliation(s)
- Lisa Marquardt
- Institute of Cellular Biochemistry, University Medicine, Humboldtallee 23, D-37073 Göttingen, Germany
| | - Michael Thumm
- Institute of Cellular Biochemistry, University Medicine, Humboldtallee 23, D-37073 Göttingen, Germany
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8
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Yong X, Jia G, Liu Z, Zhou C, Yi J, Tang Y, Chen L, Chen L, Wang Y, Sun Q, Billadeau D, Su Z, Jia D. Cryo-EM structure of the Mon1-Ccz1-RMC1 complex reveals molecular basis of metazoan RAB7A activation. Proc Natl Acad Sci U S A 2023; 120:e2301725120. [PMID: 37216550 PMCID: PMC10235969 DOI: 10.1073/pnas.2301725120] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 04/18/2023] [Indexed: 05/24/2023] Open
Abstract
Understanding of the evolution of metazoans from their unicellular ancestors is a fundamental question in biology. In contrast to fungi which utilize the Mon1-Ccz1 dimeric complex to activate the small GTPase RAB7A, metazoans rely on the Mon1-Ccz1-RMC1 trimeric complex. Here, we report a near-atomic resolution cryogenic-electron microscopy structure of the Drosophila Mon1-Ccz1-RMC1 complex. RMC1 acts as a scaffolding subunit and binds to both Mon1 and Ccz1 on the surface opposite to the RAB7A-binding site, with many of the RMC1-contacting residues from Mon1 and Ccz1 unique to metazoans, explaining the binding specificity. Significantly, the assembly of RMC1 with Mon1-Ccz1 is required for cellular RAB7A activation, autophagic functions and organismal development in zebrafish. Our studies offer a molecular explanation for the different degree of subunit conservation across species, and provide an excellent example of how metazoan-specific proteins take over existing functions in unicellular organisms.
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Affiliation(s)
- Xin Yong
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Department of Paediatrics, West China Second University Hospital, State Key Laboratory of Biotherapy and Collaborative Innovation Center of Biotherapy, Sichuan University, Chengdu610041, China
| | - Guowen Jia
- Department of Geriatrics and National Clinical Research Center for Geriatrics, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University610044Chengdu, China
| | - Zhe Liu
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Department of Paediatrics, West China Second University Hospital, State Key Laboratory of Biotherapy and Collaborative Innovation Center of Biotherapy, Sichuan University, Chengdu610041, China
| | - Chunzhuang Zhou
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Department of Paediatrics, West China Second University Hospital, State Key Laboratory of Biotherapy and Collaborative Innovation Center of Biotherapy, Sichuan University, Chengdu610041, China
| | - Jiamin Yi
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Department of Paediatrics, West China Second University Hospital, State Key Laboratory of Biotherapy and Collaborative Innovation Center of Biotherapy, Sichuan University, Chengdu610041, China
| | - Yingying Tang
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Department of Paediatrics, West China Second University Hospital, State Key Laboratory of Biotherapy and Collaborative Innovation Center of Biotherapy, Sichuan University, Chengdu610041, China
| | - Li Chen
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Department of Paediatrics, West China Second University Hospital, State Key Laboratory of Biotherapy and Collaborative Innovation Center of Biotherapy, Sichuan University, Chengdu610041, China
| | - Lu Chen
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Department of Paediatrics, West China Second University Hospital, State Key Laboratory of Biotherapy and Collaborative Innovation Center of Biotherapy, Sichuan University, Chengdu610041, China
| | - Yuan Wang
- Department of Geriatrics and National Clinical Research Center for Geriatrics, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University610044Chengdu, China
| | - Qingxiang Sun
- Department of Geriatrics and National Clinical Research Center for Geriatrics, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University610044Chengdu, China
| | - Daniel D. Billadeau
- Division of Oncology Research and Schulze Center for Novel Therapeutics, Mayo Clinic, Rochester, MN55905
| | - Zhaoming Su
- Department of Geriatrics and National Clinical Research Center for Geriatrics, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University610044Chengdu, China
| | - Da Jia
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Department of Paediatrics, West China Second University Hospital, State Key Laboratory of Biotherapy and Collaborative Innovation Center of Biotherapy, Sichuan University, Chengdu610041, China
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9
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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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10
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Zwilling E, Reggiori F. Membrane Contact Sites in Autophagy. Cells 2022; 11:3813. [PMID: 36497073 PMCID: PMC9735501 DOI: 10.3390/cells11233813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Revised: 11/24/2022] [Accepted: 11/25/2022] [Indexed: 11/29/2022] Open
Abstract
Eukaryotes utilize different communication strategies to coordinate processes between different cellular compartments either indirectly, through vesicular transport, or directly, via membrane contact sites (MCSs). MCSs have been implicated in lipid metabolism, calcium signaling and the regulation of organelle biogenesis in various cell types. Several studies have shown that MCSs play a crucial role in the regulation of macroautophagy, an intracellular catabolic transport route that is characterized by the delivery of cargoes (proteins, protein complexes or aggregates, organelles and pathogens) to yeast and plant vacuoles or mammalian lysosomes, for their degradation and recycling into basic metabolites. Macroautophagy is characterized by the de novo formation of double-membrane vesicles called autophagosomes, and their biogenesis requires an enormous amount of lipids. MCSs appear to have a central role in this supply, as well as in the organization of the autophagy-related (ATG) machinery. In this review, we will summarize the evidence for the participation of specific MCSs in autophagosome formation, with a focus on the budding yeast and mammalian systems.
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Affiliation(s)
- Emma Zwilling
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, 8000C Aarhus, Denmark
| | - Fulvio Reggiori
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, 8000C Aarhus, Denmark
- Aarhus Institute of Advanced Studies (AIAS), Aarhus University, Høegh-Guldbergs Gade 6B, 8000C Aarhus, Denmark
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11
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Chumpen Ramirez S, Gómez-Sánchez R, Verlhac P, Hardenberg R, Margheritis E, Cosentino K, Reggiori F, Ungermann C. --Atg9 interactions via its transmembrane domains are required for phagophore expansion during autophagy. Autophagy 2022:1-20. [PMID: 36354155 DOI: 10.1080/15548627.2022.2136340] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
During macroautophagy/autophagy, precursor cisterna known as phagophores expand and sequester portions of the cytoplasm and/or organelles, and subsequently close resulting in double-membrane transport vesicles called autophagosomes. Autophagosomes fuse with lysosomes/vacuoles to allow the degradation and recycling of their cargoes. We previously showed that sequential binding of yeast Atg2 and Atg18 to Atg9, the only conserved transmembrane protein in autophagy, at the extremities of the phagophore mediates the establishment of membrane contact sites between the phagophore and the endoplasmic reticulum. As the Atg2-Atg18 complex transfers lipids between adjacent membranes in vitro, it has been postulated that this activity and the scramblase activity of the trimers formed by Atg9 are required for the phagophore expansion. Here, we present evidence that Atg9 indeed promotes Atg2-Atg18 complex-mediated lipid transfer in vitro, although this is not the only requirement for its function in vivo. In particular, we show that Atg9 function is dramatically compromised by a F627A mutation within the conserved interface between the transmembrane domains of the Atg9 monomers. Although Atg9F627A self-interacts and binds to the Atg2-Atg18 complex, the F627A mutation blocks the phagophore expansion and thus autophagy progression. This phenotype is conserved because the corresponding human ATG9A mutant severely impairs autophagy as well. Importantly, Atg9F627A has identical scramblase activity in vitro like Atg9, and as with the wild-type protein enhances Atg2-Atg18-mediated lipid transfer. Collectively, our data reveal that interactions of Atg9 trimers via their transmembrane segments play a key role in phagophore expansion beyond Atg9's role as a lipid scramblase.Abbreviations: BafA1: bafilomycin A1; Cvt: cytoplasm-to-vacuole targeting; Cryo-EM: cryo-electron microscopy; ER: endoplasmic reticulum; GFP: green fluorescent protein; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MCS: membrane contact site; NBD-PE: N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine; PAS: phagophore assembly site; PE: phosphatidylethanolamine; prApe1: precursor Ape1; PtdIns3P: phosphatidylinositol-3-phosphate; SLB: supported lipid bilayer; SUV: small unilamellar vesicle; TMD: transmembrane domain; WT: wild type.
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Affiliation(s)
- Sabrina Chumpen Ramirez
- Osnabrück University, Department of Biology/Chemistry, Biochemistry section, Osnabrück, Germany
| | - Rubén Gómez-Sánchez
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Pauline Verlhac
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Ralph Hardenberg
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | | | - Katia Cosentino
- Osnabrück University, Department of Biology/Chemistry, Osnabrück, Germany.,Center of Cellular Nanoanalytic Osnabrück (CellNanOs), Osnabrück University, Osnabrück, Germany
| | - Fulvio Reggiori
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Department of Biomedicine, Aarhus University, Ole Worms Alle 4, 8000 Aarhus C, Aarhus, Denmark.,Aarhus Institute of Advanced Studies (AIAS), Aarhus University, Aarhus C, Denmark
| | - Christian Ungermann
- Osnabrück University, Department of Biology/Chemistry, Biochemistry section, Osnabrück, Germany.,Center of Cellular Nanoanalytic Osnabrück (CellNanOs), Osnabrück University, Osnabrück, Germany
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12
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Courtellemont T, De Leo MG, Gopaldass N, Mayer A. CROP: a retromer-PROPPIN complex mediating membrane fission in the endo-lysosomal system. EMBO J 2022; 41:e109646. [PMID: 35466426 PMCID: PMC9108610 DOI: 10.15252/embj.2021109646] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 03/21/2022] [Accepted: 03/24/2022] [Indexed: 01/06/2023] Open
Abstract
Endo-lysosomal compartments exchange proteins by fusing, fissioning, and through endosomal transport carriers. Thereby, they sort many plasma membrane receptors and transporters and control cellular signaling and metabolism. How the membrane fission events are catalyzed is poorly understood. Here, we identify the novel CROP complex as a factor acting at this step. CROP joins members of two protein families: the peripheral subunits of retromer, a coat forming endosomal transport carriers, and membrane inserting PROPPINs. Integration into CROP potentiates the membrane fission activity of the PROPPIN Atg18 on synthetic liposomes and confers strong preference for binding PI(3,5)P2 , a phosphoinositide required for membrane fission activity. Disrupting CROP blocks fragmentation of lysosome-like yeast vacuoles in vivo. CROP-deficient mammalian endosomes accumulate micrometer-long tubules and fail to export cargo, suggesting that carriers attempt to form but cannot separate from these organelles. PROPPINs compete for retromer binding with the SNX-BAR proteins, which recruit retromer to the membrane during the formation of endosomal carriers. Transition from retromer-SNX-BAR complexes to retromer-PROPPIN complexes might hence switch retromer activities from cargo capture to membrane fission.
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Affiliation(s)
| | | | - Navin Gopaldass
- Department of BiochemistryUniversity of LausanneEpalingesSwitzerland
| | - Andreas Mayer
- Department of BiochemistryUniversity of LausanneEpalingesSwitzerland
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13
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Abstract
Emerging resistance to artemisinin (ART) has become a challenge for reducing worldwide malaria mortality and morbidity. The C580Y mutation in Plasmodium falciparum Kelch13 has been identified as the major determinant for ART resistance in the background of other mutations, which include the T38I mutation in autophagy-related protein PfATG18. Increased endoplasmic reticulum phosphatidylinositol-3-phosphate (ER-PI3P) vesiculation, unfolded protein response (UPR), and oxidative stress are the proteostasis mechanisms proposed to cause ART resistance. While UPR and PI3P are known to stimulate autophagy in higher organisms to clear misfolded proteins, participation of the parasite autophagy machinery in these mechanisms of ART resistance has not yet been experimentally demonstrated. Our study establishes that ART-induced ER stress leads to increased expression of P. falciparum autophagy proteins through induction of the UPR. Furthermore, the ART-resistant K13C580Y isolate shows higher basal expression levels of autophagy proteins than those of its isogenic counterpart, and this magnifies under starvation conditions. The copresence of PfK13 with PfATG18 and PI3P on parasite hemoglobin-trafficking vesicles demonstrate interactions between the autophagy and hemoglobin endocytosis pathways proposed to be involved in ART resistance. Analysis of PfK13 mutations in 2,517 field isolates, revealing an impressive >85% coassociation between PfK13 C580Y and PfATG18 T38I, together with our experimental studies with an ART-resistant P. falciparum strain establishes that parasite autophagy underpins various mechanisms of ART resistance and is a starting point to further explore this pathway for developing antimalarials.
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14
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Kruasuwan W, Puseenam A, Phithakrotchanakoon C, Tanapongpipat S, Roongsawang N. Modulation of heterologous protein secretion in the thermotolerant methylotrophic yeast Ogataea thermomethanolica TBRC 656 by CRISPR-Cas9 system. PLoS One 2021; 16:e0258005. [PMID: 34582499 PMCID: PMC8478189 DOI: 10.1371/journal.pone.0258005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 09/16/2021] [Indexed: 11/18/2022] Open
Abstract
The thermotolerant methylotrophic yeast Ogataea thermomethanolica TBRC 656 is a potential host strain for industrial protein production. Heterologous proteins are often retained intracellularly in yeast resulting in endoplasmic reticulum (ER) stress and poor secretion, and despite efforts to engineer protein secretory pathways, heterologous protein production is often lower than expected. We hypothesized that activation of genes involved in the secretory pathway could mitigate ER stress. In this study, we created mutants defective in protein secretory-related functions using clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9) tools. Secretion of the model protein xylanase was significantly decreased in loss of function mutants for oxidative stress (sod1Δ) and vacuolar and protein sorting (vps1Δ and ypt7Δ) genes. However, xylanase secretion was unaffected in an autophagy related atg12Δ mutant. Then, we developed a system for sequence-specific activation of target gene expression (CRISPRa) in O. thermomethanolica and used it to activate SOD1, VPS1 and YPT7 genes. Production of both non-glycosylated xylanase and glycosylated phytase was enhanced in the gene activated mutants, demonstrating that CRISPR-Cas9 systems can be used as tools for understanding O. thermomethanolica genes involved in protein secretion, which could be applied for increasing heterologous protein secretion in this yeast.
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Affiliation(s)
- Worarat Kruasuwan
- Microbial Cell Factory Research Team, Microbial Biotechnology and Biochemicals Research Unit, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Khlong Nueng, Khlong Luang, Pathum Thani, Thailand
| | - Aekkachai Puseenam
- Microbial Cell Factory Research Team, Microbial Biotechnology and Biochemicals Research Unit, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Khlong Nueng, Khlong Luang, Pathum Thani, Thailand
| | - Chitwadee Phithakrotchanakoon
- Microbial Systems and Computational Biology Research Team, Thailand Bioresource Research Center, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Khlong Nueng, Khlong Luang, Pathum Thani, Thailand
| | - Sutipa Tanapongpipat
- Microbial Cell Factory Research Team, Microbial Biotechnology and Biochemicals Research Unit, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Khlong Nueng, Khlong Luang, Pathum Thani, Thailand
| | - Niran Roongsawang
- Microbial Cell Factory Research Team, Microbial Biotechnology and Biochemicals Research Unit, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Khlong Nueng, Khlong Luang, Pathum Thani, Thailand
- * E-mail:
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15
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Vincent O, Antón-Esteban L, Bueno-Arribas M, Tornero-Écija A, Navas MÁ, Escalante R. The WIPI Gene Family and Neurodegenerative Diseases: Insights From Yeast and Dictyostelium Models. Front Cell Dev Biol 2021; 9:737071. [PMID: 34540850 PMCID: PMC8442847 DOI: 10.3389/fcell.2021.737071] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 08/12/2021] [Indexed: 02/01/2023] Open
Abstract
WIPIs are a conserved family of proteins with a characteristic 7-bladed β-propeller structure. They play a prominent role in autophagy, but also in other membrane trafficking processes. Mutations in human WIPI4 cause several neurodegenerative diseases. One of them is BPAN, a rare disease characterized by developmental delay, motor disorders, and seizures. Autophagy dysfunction is thought to play an important role in this disease but the precise pathological consequences of the mutations are not well established. The use of simple models such as the yeast Saccharomyces cerevisiae and the social amoeba Dictyostelium discoideum provides valuable information on the molecular and cellular function of these proteins, but also sheds light on possible pathways that may be relevant in the search for potential therapies. Here, we review the function of WIPIs as well as disease-causing mutations with a special focus on the information provided by these simple models.
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Affiliation(s)
- Olivier Vincent
- Instituto de Investigaciones Biomédicas Alberto Sols CSIC/UAM, Madrid, Spain
| | - Laura Antón-Esteban
- Instituto de Investigaciones Biomédicas Alberto Sols CSIC/UAM, Madrid, Spain
| | | | - Alba Tornero-Écija
- Instituto de Investigaciones Biomédicas Alberto Sols CSIC/UAM, Madrid, Spain
| | - María-Ángeles Navas
- Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad Complutense de Madrid, Madrid, Spain
| | - Ricardo Escalante
- Instituto de Investigaciones Biomédicas Alberto Sols CSIC/UAM, Madrid, Spain
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16
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Escobar-Niño A, Morano Bermejo IM, Carrasco Reinado R, Fernandez-Acero FJ. Deciphering the Dynamics of Signaling Cascades and Virulence Factors of B. cinerea during Tomato Cell Wall Degradation. Microorganisms 2021; 9:microorganisms9091837. [PMID: 34576732 PMCID: PMC8466851 DOI: 10.3390/microorganisms9091837] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 08/11/2021] [Accepted: 08/24/2021] [Indexed: 11/30/2022] Open
Abstract
The ascomycete Botrytis cinerea is one of the most relevant plant pathogenic fungi, affecting fruits, flowers, and greenhouse-grown crops. The infection strategy used by the fungus comprises a magnificent set of tools to penetrate and overcome plant defenses. In this context, the plant-pathogen communication through membrane receptors and signal transduction cascades is essential to trigger specific routes and the final success of the infection. In previous reports, proteomics approaches to B. cinerea signal transduction cascades changes in response to different carbon source and plant-based elicitors have been performed. Analyzing the secretome, membranome, phosphoproteome, and the phosphomembranome. Moreover, phenotypic changes in fungal biology was analyzed, specifically toxin production. To obtain the whole picture of the process and reveal the network from a system biology approach, this proteomic information has been merged with the phenotypic characterization, to be analyzed using several bioinformatics algorithms (GO, STRING, MCODE) in order to unravel key points in the signal transduction regulation crucial to overcome plant defenses, as well as new virulence/pathogenicity factors that could be used as therapeutic targets in the control of the gray mold rot disease. A total of 1721 and 663 exclusive or overexpressed proteins were identified under glucose (GLU) and deproteinized tomato cell walls (TCW), summarizing all of the protein identifications under phenotypic characterized stages. Under GO analysis, there are more biological process and molecular functions described in GLU, highlighting the increase in signaling related categories. These results agree with the high number of total identified proteins in GLU, probably indicating a more varied and active metabolism of the fungus. When analyzing only GO annotations related with signal transduction, it was revealed that there were proteins related to TOR signaling, the phosphorelay signal transduction system, and inositol lipid-mediated signaling, only under GLU conditions. On the contrary, calcium-mediated signaling GO annotation is only present between the proteins identified under TCW conditions. To establish a potential relationship between expressed proteins, cluster analyses showed 41 and 14 clusters under GLU and TCW conditions, confirming an increase in biological activity in GLU, where we identified a larger number of clusters related to transcription, translation, and cell division, between others. From these analyses, clusters related to signal transduction and clusters related to mycotoxin production were found, which correlated with the phenotypic characterization. The identification of the proteins encompassed in each condition and signal transduction cascade would provide the research community with new information about the B. cinerea infection process and potential candidates of pathogenicity/virulence factors, overcoming plant defenses, and new therapeutic targets.
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17
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Bueno-Arribas M, Blanca I, Cruz-Cuevas C, Escalante R, Navas MA, Vincent O. A conserved ATG2 binding site in WIPI4 and yeast Hsv2 is disrupted by mutations causing β-propeller protein-associated neurodegeneration. Hum Mol Genet 2021; 31:111-121. [PMID: 34368840 PMCID: PMC8682751 DOI: 10.1093/hmg/ddab225] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 01/18/2023] Open
Abstract
PROPPINs are phosphoinositide-binding β-propeller proteins that mediate membrane recruitment of other proteins and are involved in different membrane remodeling processes. The main role of PROPPINs is their function in autophagy, where they act at different steps in phagophore formation. The human PROPPIN WIPI4 (WDR45) forms a complex with ATG2 involved in phagophore elongation, and mutations in this gene cause β-propeller protein-associated neurodegeneration (BPAN). The yeast functional counterpart of WIPI4 is Atg18, although its closest sequence homolog is another member of the PROPPIN family, Hsv2, whose function remains largely undefined. Here, we provide evidence that Hsv2, like WIPI4 and Atg18, interacts with Atg2. We show that Hsv2 and a pool of Atg2 colocalize on endosomes under basal conditions and at the pre-autophagosomal structure (PAS) upon autophagy induction. We further show that Hsv2 drives the recruitment of Atg2 to endosomes while Atg2 mediates Hsv2 recruitment to the PAS. HSV2 overexpression results in mis-sorting and secretion of carboxypeptidase CPY, suggesting that the endosomal function of this protein is related to the endosome-to-Golgi recycling pathway. Furthermore, we show that the Atg2 binding site is conserved in Hsv2 and WIPI4 but not in Atg18. Notably, two WIPI4 residues involved in ATG2 binding are mutated in patients with BPAN, and there is a correlation between the inhibitory effect of these mutations on ATG2 binding and the severity of the disease.
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Affiliation(s)
| | - Irene Blanca
- Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad Complutense de Madrid, Madrid, Spain
| | - Celia Cruz-Cuevas
- Instituto de Investigaciones Biomédicas CSIC-UAM 28029 Madrid, Spain
| | - Ricardo Escalante
- Instituto de Investigaciones Biomédicas CSIC-UAM 28029 Madrid, Spain
| | - María-Angeles Navas
- Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad Complutense de Madrid, Madrid, Spain
| | - Olivier Vincent
- Instituto de Investigaciones Biomédicas CSIC-UAM 28029 Madrid, Spain
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18
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Aman Y, Schmauck-Medina T, Hansen M, Morimoto RI, Simon AK, Bjedov I, Palikaras K, Simonsen A, Johansen T, Tavernarakis N, Rubinsztein DC, Partridge L, Kroemer G, Labbadia J, Fang EF. Autophagy in healthy aging and disease. NATURE AGING 2021; 1:634-650. [PMID: 34901876 PMCID: PMC8659158 DOI: 10.1038/s43587-021-00098-4] [Citation(s) in RCA: 518] [Impact Index Per Article: 172.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 07/07/2021] [Indexed: 12/12/2022]
Abstract
Autophagy is a fundamental cellular process that eliminates molecules and subcellular elements, including nucleic acids, proteins, lipids and organelles, via lysosome-mediated degradation to promote homeostasis, differentiation, development and survival. While autophagy is intimately linked to health, the intricate relationship among autophagy, aging and disease remains unclear. This Review examines several emerging features of autophagy and postulates how they may be linked to aging as well as to the development and progression of disease. In addition, we discuss current preclinical evidence arguing for the use of autophagy modulators as suppressors of age-related pathologies such as neurodegenerative diseases. Finally, we highlight key questions and propose novel research avenues that will likely reveal new links between autophagy and the hallmarks of aging. Understanding the precise interplay between autophagy and the risk of age-related pathologies across organisms will eventually facilitate the development of clinical applications that promote long-term health.
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Affiliation(s)
- Yahyah Aman
- Department of Clinical Molecular Biology, University of Oslo and Akershus University Hospital, Lørenskog, Norway
- Institute of Healthy Ageing, Department of Genetics, Evolution and Environment, University College London, London, UK
- These authors contributed equally: Yahyah Aman, Tomas Schmauck-Medina
| | - Tomas Schmauck-Medina
- Department of Clinical Molecular Biology, University of Oslo and Akershus University Hospital, Lørenskog, Norway
- These authors contributed equally: Yahyah Aman, Tomas Schmauck-Medina
| | - Malene Hansen
- Development, Aging and Regeneration Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Richard I. Morimoto
- Department of Molecular Biosciences, Rice Institute for Biomedical Research, Northwestern University, Evanston, IL, USA
| | | | - Ivana Bjedov
- Institute of Healthy Ageing, Department of Genetics, Evolution and Environment, University College London, London, UK
- UCL Cancer Institute, University College London, London, UK
| | - Konstantinos Palikaras
- Department of Physiology, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece
| | - Anne Simonsen
- Department of Molecular Medicine, Institute of Basic Medical Sciences and Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, The University of Oslo, Oslo, Norway
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, Oslo, Norway
| | - Terje Johansen
- Molecular Cancer Research Group, Institute of Medical Biology, University of Tromsø–The Arctic University of Norway, Tromsø, Norway
| | - Nektarios Tavernarakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology–Hellas, Heraklion, Greece
- Department of Basic Sciences, School of Medicine, University of Crete, Heraklion, Greece
| | - David C. Rubinsztein
- Department of Medical Genetics, Cambridge Institute for Medical Research, Cambridge, UK
- UK Dementia Research Institute, University of Cambridge, Cambridge, UK
| | - Linda Partridge
- Institute of Healthy Ageing, Department of Genetics, Evolution and Environment, University College London, London, UK
- Department of Biological Mechanisms of Ageing, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Guido Kroemer
- Centre de Recherche des Cordeliers, Equipe Labellisée par la Ligue contre le Cancer, Université de Paris, Sorbonne Université, INSERM U1138, Institut Universitaire de France, Paris, France
- Metabolomics and Cell Biology Platforms, Gustave Roussy, Villejuif, France
- Pôle de Biologie, Hôpital Européen Georges Pompidou, AP-HP, Paris, France
- Suzhou Institute for Systems Medicine, Chinese Academy of Medical Sciences, Suzhou, China
- Karolinska Institute, Department of Women’s and Children’s Health, Karolinska University Hospital, Stockholm, Sweden
| | - John Labbadia
- Institute of Healthy Ageing, Department of Genetics, Evolution and Environment, University College London, London, UK
| | - Evandro F. Fang
- Department of Clinical Molecular Biology, University of Oslo and Akershus University Hospital, Lørenskog, Norway
- The Norwegian Centre on Healthy Ageing (NO-Age), Oslo, Norway
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19
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Tornero-Écija A, Tábara LC, Bueno-Arribas M, Antón-Esteban L, Navarro-Gómez C, Sánchez I, Vincent O, Escalante R. A Dictyostelium model for BPAN disease reveals a functional relationship between the WDR45/WIPI4 homolog Wdr45l and Vmp1 in the regulation of autophagy-associated PtdIns3P and ER stress. Autophagy 2021; 18:661-677. [PMID: 34328055 PMCID: PMC9037511 DOI: 10.1080/15548627.2021.1953262] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
PROPPINs are conserved PtdIns3P-binding proteins required for autophagosome biogenesis that fold into a characteristic group of seven-bladed beta-propellers. Mutations in WDR45/WIPI4, a human member of this family, lead to BPAN, a rare form of neurodegeneration. We have generated mutants for the two PROPPIN proteins present in the model system Dictyostelium discoideum (Atg18 and Wdr45l) and characterized their function. Lack of Wdr45l greatly impairs autophagy, while Atg18 only causes subtle defects in the maturation of autolysosomes. The strong phenotype of the Wdr45l mutant is strikingly similar to that observed in Dictyostelium cells lacking Vmp1, an ER protein required for omegasome formation. Common phenotypes include impaired growth in axenic medium, lack of aggregation, and local enrichment of PtdIns3P as determined by the use of lipid reporters. In addition, Vmp1 and Wdr45l mutants show a chronically active response to ER stress. For both mutants, this altered PtdIns3P localization can be prevented by the additional mutation of the upstream regulator Atg1, which also leads to recovery of axenic growth and reduction of ER stress. We propose that, in addition to an autophagy defect, local autophagy-associated PtdIns3P accumulation might contribute to the pathogenesis of BPAN by disrupting ER homeostasis. The introduction of BPAN-associated mutations in Dictyostelium Wdr45l reveals the impact of pathogenic residues on the function and localization of the protein.
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Affiliation(s)
- Alba Tornero-Écija
- C.S.I.C./U.A.M., Instituto De Investigaciones Biomédicas Alberto Sols, Madrid, Spain
| | - Luis-Carlos Tábara
- C.S.I.C./U.A.M., Instituto De Investigaciones Biomédicas Alberto Sols, Madrid, Spain
| | - Miranda Bueno-Arribas
- C.S.I.C./U.A.M., Instituto De Investigaciones Biomédicas Alberto Sols, Madrid, Spain
| | - Laura Antón-Esteban
- C.S.I.C./U.A.M., Instituto De Investigaciones Biomédicas Alberto Sols, Madrid, Spain
| | | | - Irene Sánchez
- C.S.I.C./U.A.M., Instituto De Investigaciones Biomédicas Alberto Sols, Madrid, Spain
| | - Olivier Vincent
- C.S.I.C./U.A.M., Instituto De Investigaciones Biomédicas Alberto Sols, Madrid, Spain
| | - Ricardo Escalante
- C.S.I.C./U.A.M., Instituto De Investigaciones Biomédicas Alberto Sols, Madrid, Spain
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20
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Ran T, Ke S, Song X, Ma T, Xu Y, Wang M. WIPI1 promotes osteosarcoma cell proliferation by inhibiting CDKN1A. Gene 2021; 782:145537. [PMID: 33636294 DOI: 10.1016/j.gene.2021.145537] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 01/24/2021] [Accepted: 02/11/2021] [Indexed: 02/06/2023]
Abstract
Detection of TCGA data revealed that WIPI1 is highly expressed in osteosarcoma cells. So we explore the mechanisms of WIPI1 affecting the proliferation of osteosarcoma cells through Affymetrix microarray analysis. Functional analysis of differentially expressed genes shows that the classical signaling pathways affecting tumor formation and development have changed significantly. By fitting analysis, it is speculated that the WIPI1 may function in the direction of osteosarcoma by regulating the expression of multiple cell cycle-related genes such as CDKN1A, CDK4 and CCND1. Therefore, the key genes are selected for RT-PCR and Western-blot verification. Combined with flow and other means, WIPI1 may affect the cell cycle and the osteosarcoma by regulating the expression of CDKN1A, CDK4 and CCND1. To verify the results, the effect of WIPI1 on cell proliferation was quantified by MTT, cell counts and nude mouse tumorigenicity assay. The results showed that WIPI1 promotes osteosarcoma cell proliferation.
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Affiliation(s)
- Tianfei Ran
- Orthopeadic Dept. Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Song Ke
- Orthopeadic Dept. Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Xin Song
- Orthopeadic Dept. Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Tianying Ma
- Orthopeadic Dept. Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Yuan Xu
- Orthopeadic Dept. Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Min Wang
- Orthopeadic Dept. Xinqiao Hospital, Army Medical University, Chongqing, China.
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21
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Gomez RE, Lupette J, Chambaud C, Castets J, Ducloy A, Cacas JL, Masclaux-Daubresse C, Bernard A. How Lipids Contribute to Autophagosome Biogenesis, a Critical Process in Plant Responses to Stresses. Cells 2021; 10:1272. [PMID: 34063958 PMCID: PMC8224036 DOI: 10.3390/cells10061272] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 05/03/2021] [Accepted: 05/17/2021] [Indexed: 01/18/2023] Open
Abstract
Throughout their life cycle, plants face a tremendous number of environmental and developmental stresses. To respond to these different constraints, they have developed a set of refined intracellular systems including autophagy. This pathway, highly conserved among eukaryotes, is induced by a wide range of biotic and abiotic stresses upon which it mediates the degradation and recycling of cytoplasmic material. Central to autophagy is the formation of highly specialized double membrane vesicles called autophagosomes which select, engulf, and traffic cargo to the lytic vacuole for degradation. The biogenesis of these structures requires a series of membrane remodeling events during which both the quantity and quality of lipids are critical to sustain autophagy activity. This review highlights our knowledge, and raises current questions, regarding the mechanism of autophagy, and its induction and regulation upon environmental stresses with a particular focus on the fundamental contribution of lipids. How autophagy regulates metabolism and the recycling of resources, including lipids, to promote plant acclimation and resistance to stresses is further discussed.
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Affiliation(s)
- Rodrigo Enrique Gomez
- Laboratoire de Biogenèse Membranaire, UMR 5200, CNRS, Université de Bordeaux, F-33140 Villenave d’Ornon, France; (R.E.G.); (J.L.); (C.C.); (J.C.)
| | - Josselin Lupette
- Laboratoire de Biogenèse Membranaire, UMR 5200, CNRS, Université de Bordeaux, F-33140 Villenave d’Ornon, France; (R.E.G.); (J.L.); (C.C.); (J.C.)
| | - Clément Chambaud
- Laboratoire de Biogenèse Membranaire, UMR 5200, CNRS, Université de Bordeaux, F-33140 Villenave d’Ornon, France; (R.E.G.); (J.L.); (C.C.); (J.C.)
| | - Julie Castets
- Laboratoire de Biogenèse Membranaire, UMR 5200, CNRS, Université de Bordeaux, F-33140 Villenave d’Ornon, France; (R.E.G.); (J.L.); (C.C.); (J.C.)
| | - Amélie Ducloy
- Institut Jean-Pierre Bourgin, UMR 1318 AgroParisTech-INRAE, Université Paris-Saclay, 78000 Versailles, France; (A.D.); (J.-L.C.); (C.M.-D.)
| | - Jean-Luc Cacas
- Institut Jean-Pierre Bourgin, UMR 1318 AgroParisTech-INRAE, Université Paris-Saclay, 78000 Versailles, France; (A.D.); (J.-L.C.); (C.M.-D.)
| | - Céline Masclaux-Daubresse
- Institut Jean-Pierre Bourgin, UMR 1318 AgroParisTech-INRAE, Université Paris-Saclay, 78000 Versailles, France; (A.D.); (J.-L.C.); (C.M.-D.)
| | - Amélie Bernard
- Laboratoire de Biogenèse Membranaire, UMR 5200, CNRS, Université de Bordeaux, F-33140 Villenave d’Ornon, France; (R.E.G.); (J.L.); (C.C.); (J.C.)
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22
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Plasmodium falciparum Atg18 localizes to the food vacuole via interaction with the multi-drug resistance protein 1 and phosphatidylinositol 3-phosphate. Biochem J 2021; 478:1705-1732. [PMID: 33843972 DOI: 10.1042/bcj20210001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 04/10/2021] [Accepted: 04/12/2021] [Indexed: 12/27/2022]
Abstract
Autophagy, a lysosome-dependent degradative process, does not appear to be a major degradative process in malaria parasites and has a limited repertoire of genes. To better understand the autophagy process, we investigated Plasmodium falciparum Atg18 (PfAtg18), a PROPPIN family protein, whose members like S. cerevisiae Atg18 (ScAtg18) and human WIPI2 bind PI3P and play an essential role in autophagosome formation. Wild type and mutant PfAtg18 were expressed in P. falciparum and assessed for localization, the effect of various inhibitors and antimalarials on PfAtg18 localization, and identification of PfAtg18-interacting proteins. PfAtg18 is expressed in asexual erythrocytic stages and localized to the food vacuole, which was also observed with other Plasmodium Atg18 proteins, indicating that food vacuole localization is likely a shared feature. Interaction of PfAtg18 with the food vacuole-associated PI3P is essential for localization, as PfAtg18 mutants of PI3P-binding motifs neither bound PI3P nor localized to the food vacuole. Interestingly, wild type ScAtg18 interacted with PI3P, but its expression in P. falciparum showed complete cytoplasmic localization, indicating additional requirement for food vacuole localization. The food vacuole multi-drug resistance protein 1 (MDR1) was consistently identified in the immunoprecipitates of PfAtg18 and P. berghei Atg18, and also interacted with PfAtg18. In contrast with PfAtg18, ScAtg18 did not interact with MDR1, which, in addition to PI3P, could play a critical role in localization of PfAtg18. Chloroquine and amodiaquine caused cytoplasmic localization of PfAtg18, suggesting that these target PfAtg18 transport pathway. Thus, PI3P and MDR1 are critical mediators of PfAtg18 localization.
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Cong Y, So V, Tijssen MAJ, Verbeek DS, Reggiori F, Mauthe M. WDR45, one gene associated with multiple neurodevelopmental disorders. Autophagy 2021; 17:3908-3923. [PMID: 33843443 PMCID: PMC8726670 DOI: 10.1080/15548627.2021.1899669] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The WDR45 gene is localized on the X-chromosome and variants in this gene are linked to six different neurodegenerative disorders, i.e., ß-propeller protein associated neurodegeneration, Rett-like syndrome, intellectual disability, and epileptic encephalopathies including developmental and epileptic encephalopathy, early-onset epileptic encephalopathy and West syndrome and potentially also specific malignancies. WDR45/WIPI4 is a WD-repeat β-propeller protein that belongs to the WIPI (WD repeat domain, phosphoinositide interacting) family. The precise cellular function of WDR45 is still largely unknown, but deletions or conventional variants in WDR45 can lead to macroautophagy/autophagy defects, malfunctioning mitochondria, endoplasmic reticulum stress and unbalanced iron homeostasis, suggesting that this protein functions in one or more pathways regulating directly or indirectly those processes. As a result, the underlying cause of the WDR45-associated disorders remains unknown. In this review, we summarize the current knowledge about the cellular and physiological functions of WDR45 and highlight how genetic variants in its encoding gene may contribute to the pathophysiology of the associated diseases. In particular, we connect clinical manifestations of the disorders with their potential cellular origin of malfunctioning and critically discuss whether it is possible that one of the most prominent shared features, i.e., brain iron accumulation, is the primary cause for those disorders. Abbreviations: ATG/Atg: autophagy related; BPAN: ß-propeller protein associated neurodegeneration; CNS: central nervous system; DEE: developmental and epileptic encephalopathy; EEG: electroencephalograph; ENO2/neuron-specific enolase, enolase 2; EOEE: early-onset epileptic encephalopathy; ER: endoplasmic reticulum; ID: intellectual disability; IDR: intrinsically disordered region; MRI: magnetic resonance imaging; NBIA: neurodegeneration with brain iron accumulation; NCOA4: nuclear receptor coactivator 4; PtdIns3P: phosphatidylinositol-3-phosphate; RLS: Rett-like syndrome; WDR45: WD repeat domain 45; WIPI: WD repeat domain, phosphoinositide interacting
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Affiliation(s)
- Yingying Cong
- Department of Biomedical Sciences of Cells & Systems, Molecular Cell Biology Section, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Vincent So
- Department of Biomedical Sciences of Cells & Systems, Molecular Cell Biology Section, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Marina A J Tijssen
- Department of Neurology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Expertise Center Movement Disorders Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Dineke S Verbeek
- Expertise Center Movement Disorders Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Fulvio Reggiori
- Department of Biomedical Sciences of Cells & Systems, Molecular Cell Biology Section, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Expertise Center Movement Disorders Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Mario Mauthe
- Department of Biomedical Sciences of Cells & Systems, Molecular Cell Biology Section, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Expertise Center Movement Disorders Groningen, University Medical Center Groningen, Groningen, The Netherlands
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24
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Lei Y, Tang D, Liao G, Xu L, Liu S, Chen Q, Li C, Duan J, Wang K, Wang J, Sun B, Li Z, Dai L, Cheng W, Qi S, Lu K. The crystal structure of Atg18 reveals a new binding site for Atg2 in Saccharomyces cerevisiae. Cell Mol Life Sci 2021; 78:2131-2143. [PMID: 32809042 PMCID: PMC11073433 DOI: 10.1007/s00018-020-03621-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 07/24/2020] [Accepted: 08/11/2020] [Indexed: 02/07/2023]
Abstract
Macroautophagy (hereafter referred to as autophagy) is a highly conserved catabolic eukaryotic pathway that is critical for stress responses and homeostasis. Atg18, one of the core proteins involved in autophagy, belongs to the PROPPIN family and is composed of seven WD40 repeats. Together with Atg2, Atg18 participates in the elongation of phagophores and the recycling of Atg9 in yeast. Despite extensive studies on the PROPPIN family, the structure of Atg18 from Saccharomyces cerevisiae has not been determined. Here, we report the structure of ScAtg18 at a resolution of 2.8 Å. Based on bioinformatics and structural analysis, we found that the 7AB loop of ScAtg18 is extended in Atg18, in comparison to other members of the PROPPIN family. Genetic analysis revealed that the 7AB loop of ScAtg18 is required for autophagy. Biochemical and biophysical experiments indicated that the 7AB loop of ScAtg18 is critical for interaction with ScAtg2 and the recruitment of ScAtg2 to the autophagy-initiating site. Collectively, our results show that the 7AB loop of ScAtg18 is a new binding site for Atg2 and is of functional importance to autophagy.
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Affiliation(s)
- Yuqing Lei
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, Chengdu, China
| | - Dan Tang
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, Chengdu, China
| | - Ga Liao
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Chinese Academy of Medical Sciences Research Unit of Oral Carcinogenesis and Management, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Liangting Xu
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, Chengdu, China
| | - Shiyan Liu
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, Chengdu, China
| | - Qianqian Chen
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, Chengdu, China
| | - Chunxia Li
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, Chengdu, China
| | - Jinsong Duan
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Kunjie Wang
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, Chengdu, China
| | - Jiawei Wang
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Bo Sun
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, China
| | - Zhonghan Li
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, Chengdu, China
| | - Lunzhi Dai
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, Chengdu, China
| | - Wei Cheng
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, Chengdu, China
| | - Shiqian Qi
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, Chengdu, China.
| | - Kefeng Lu
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, Chengdu, China.
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25
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Steinfeld N, Lahiri V, Morrison A, Metur SP, Klionsky DJ, Weisman LS. Elevating PI3P drives select downstream membrane trafficking pathways. Mol Biol Cell 2020; 32:143-156. [PMID: 33237833 PMCID: PMC8120694 DOI: 10.1091/mbc.e20-03-0191] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Phosphoinositide signaling lipids are essential for several cellular processes. The requirement for a phosphoinositide is conventionally studied by depleting the corresponding lipid kinase. However, there are very few reports on the impact of elevating phosphoinositides. That phosphoinositides are dynamically elevated in response to stimuli suggests that, in addition to being required, phosphoinositides drive downstream pathways. To test this hypothesis, we elevated the levels of phosphatidylinositol-3-phosphate (PI3P) by generating hyperactive alleles of the yeast phosphatidylinositol 3-kinase, Vps34. We find that hyperactive Vps34 drives certain pathways, including phosphatidylinositol-3,5-bisphosphate synthesis and retrograde transport from the vacuole. This demonstrates that PI3P is rate limiting in some pathways. Interestingly, hyperactive Vps34 does not affect endosomal sorting complexes required for transport (ESCRT) function. Thus, elevating PI3P does not always increase the rate of PI3P-dependent pathways. Elevating PI3P can also delay a pathway. Elevating PI3P slowed late steps in autophagy, in part by delaying the disassembly of autophagy proteins from mature autophagosomes as well as delaying fusion of autophagosomes with the vacuole. This latter defect is likely due to a more general defect in vacuole fusion, as assessed by changes in vacuole morphology. These studies suggest that stimulus-induced elevation of phosphoinositides provides a way for these stimuli to selectively regulate downstream processes.
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Affiliation(s)
- Noah Steinfeld
- Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI 48109.,Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109
| | - Vikramjit Lahiri
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109.,Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Anna Morrison
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109
| | - Shree Padma Metur
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109.,Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Daniel J Klionsky
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109.,Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Lois S Weisman
- Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI 48109.,Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109.,Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
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26
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Dudley LJ, Makar AN, Gammoh N. Membrane targeting of core autophagy players during autophagosome biogenesis. FEBS J 2020; 287:4806-4821. [PMID: 32301577 DOI: 10.1111/febs.15334] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 03/27/2020] [Accepted: 04/14/2020] [Indexed: 12/18/2022]
Abstract
Autophagosomes are vital organelles required to facilitate the lysosomal degradation of cytoplasmic cargo, thereby playing an important role in maintaining cellular homeostasis. A number of autophagy-related (ATG) protein complexes are recruited to the site of autophagosome biogenesis where they act to facilitate membrane growth and maturation. Regulated recruitment of ATG complexes to autophagosomal membranes is essential for their autophagic activities and is required to ensure the efficient engulfment of cargo destined for lysosomal degradation. In this review, we discuss our current understanding of the spatiotemporal hierarchy between ATG proteins, examining the mechanisms underlying their recruitment to membranes. A particular focus is placed on the relevance of phosphatidylinositol 3-phosphate and the extent to which the core autophagy players are reliant on this lipid for their localisation to autophagic membranes. In addition, open questions and potential future research directions regarding the membrane recruitment and displacement of ATG proteins are discussed here.
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Affiliation(s)
- Leo J Dudley
- Cancer Research UK Edinburgh Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, UK
| | - Agata N Makar
- Cancer Research UK Edinburgh Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, UK
| | - Noor Gammoh
- Cancer Research UK Edinburgh Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, UK
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27
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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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28
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Abstract
Autophagy is a conserved vacuole/lysosome-mediated degradation pathway for clearing and recycling cellular components including cytosol, macromolecules, and dysfunctional organelles. In recent years, autophagy has emerged to play important roles in plant-pathogen interactions. It acts as an antiviral defense mechanism in plants. Moreover, increasing evidence shows that plant viruses can manipulate, hijack, or even exploit the autophagy pathway to promote pathogenesis, demonstrating the pivotal role of autophagy in the evolutionary arms race between hosts and viruses. In this review, we discuss recent findings about the antiviral and proviral roles of autophagy in plant-virus interactions.
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Affiliation(s)
- Meng Yang
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China;
| | - Asigul Ismayil
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China;
| | - Yule Liu
- MOE Key Laboratory of Bioinformatics, Center for Plant Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China;
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29
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Emerging roles of ATG proteins and membrane lipids in autophagosome formation. Cell Discov 2020; 6:32. [PMID: 32509328 PMCID: PMC7248066 DOI: 10.1038/s41421-020-0161-3] [Citation(s) in RCA: 153] [Impact Index Per Article: 38.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 03/21/2020] [Indexed: 12/12/2022] Open
Abstract
Autophagosome biogenesis is a dynamic membrane event, which is executed by the sequential function of autophagy-related (ATG) proteins. Upon autophagy induction, a cup-shaped membrane structure appears in the cytoplasm, then elongates sequestering cytoplasmic materials, and finally forms a closed double membrane autophagosome. However, how this complex vesicle formation event is strictly controlled and achieved is still enigmatic. Recently, there is accumulating evidence showing that some ATG proteins have the ability to directly interact with membranes, transfer lipids between membranes and regulate lipid metabolism. A novel role for various membrane lipids in autophagosome formation is also emerging. Here, we highlight past and recent key findings on the function of ATG proteins related to autophagosome biogenesis and consider how ATG proteins control this dynamic membrane formation event to organize the autophagosome by collaborating with membrane lipids.
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30
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Abstract
Neurodegenerative diseases are, at present, major socio-economic burdens without effective treatments and their increasing prevalence means that these diseases will be a challenge for future generations. Neurodegenerative diseases may differ in etiology and pathology but are often caused by the accumulation of dysfunctional and aggregation-prone proteins. Autophagy, a conserved cellular mechanism, deals with cellular stress and waste product build-up and has been shown to reduce the accumulation of dysfunctional proteins in animal models of neurodegenerative diseases. Historically, progress in understanding the precise function of lipids has traditionally been far behind other biological molecules (like proteins) but emerging works demonstrate the importance of lipids in the autophagy pathway and how the disturbance of lipid metabolism is connected to neurodegeneration. Here we review how altered autophagy and the disturbance of lipid metabolism, particularly of phosphoinositols and sphingolipids, feature in neurodegenerative diseases and address work from the field that suggests that these potentially offer an opportunity of therapeutic intervention.
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Affiliation(s)
- Sergio Hernandez-Diaz
- Université de Bordeaux, Institut des Maladies Neurodégénératives, UMR 5293, 33000, Bordeaux, France.,CNRS, Institut des Maladies Neurodégénératives, UMR 5293, 33000, Bordeaux, France
| | - Sandra-Fausia Soukup
- Université de Bordeaux, Institut des Maladies Neurodégénératives, UMR 5293, 33000, Bordeaux, France.,CNRS, Institut des Maladies Neurodégénératives, UMR 5293, 33000, Bordeaux, France
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31
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Park H, Kang JH, Lee S. Autophagy in Neurodegenerative Diseases: A Hunter for Aggregates. Int J Mol Sci 2020; 21:ijms21093369. [PMID: 32397599 PMCID: PMC7247013 DOI: 10.3390/ijms21093369] [Citation(s) in RCA: 104] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 05/07/2020] [Accepted: 05/07/2020] [Indexed: 12/14/2022] Open
Abstract
Cells have developed elaborate quality-control mechanisms for proteins and organelles to maintain cellular homeostasis. Such quality-control mechanisms are maintained by conformational folding via molecular chaperones and by degradation through the ubiquitin-proteasome or autophagy-lysosome system. Accumulating evidence suggests that impaired autophagy contributes to the accumulation of intracellular inclusion bodies consisting of misfolded proteins, which is a hallmark of most neurodegenerative diseases. In addition, genetic mutations in core autophagy-related genes have been reported to be linked to neurodegenerative diseases, such as Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease. Conversely, the pathogenic proteins, such as amyloid β and α-synuclein, are detrimental to the autophagy pathway. Here, we review the recent advances in understanding the relationship between autophagic defects and the pathogenesis of neurodegenerative diseases and suggest autophagy induction as a promising strategy for the treatment of these conditions.
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Affiliation(s)
- Hyungsun Park
- Department of Anatomy, College of Medicine, Inha University, Incheon 22212, Korea;
- Hypoxia-related Disease Research Center, College of Medicine, Inha University, Incheon 22212, Korea;
| | - Ju-Hee Kang
- Hypoxia-related Disease Research Center, College of Medicine, Inha University, Incheon 22212, Korea;
- Department of Pharmacology, College of Medicine, Inha University, Incheon 22212, Korea
| | - Seongju Lee
- Department of Anatomy, College of Medicine, Inha University, Incheon 22212, Korea;
- Hypoxia-related Disease Research Center, College of Medicine, Inha University, Incheon 22212, Korea;
- Correspondence: ; Tel.: +82-32-860-9891
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Abstract
Autophagy is a conserved catabolic process critical for cell homeostasis with broad implications for aging and age-associated diseases. A defining feature of autophagy is the
de novo formation of a specialized transient organelle, the double-membrane autophagosome. Autophagosomes originate from small vesicular precursors after rapid membrane expansion resulting in the engulfment of a broad spectrum of cytoplasmic cargoes within a few minutes for vacuolar or lysosomal degradation. Recent advances have provided exciting new insights into the molecular mechanisms underlying the assembly of autophagic membranes during autophagosome biogenesis. Specifically, the phospholipid biosynthesis activity of the endoplasmic reticulum and a dedicated membrane-tethering complex between nascent autophagosomes and the endoplasmic reticulum have emerged as key factors in autophagosome formation.
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Affiliation(s)
- Martin Graef
- Max Planck Institute for Biology of Ageing, Cologne, 50931, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, 50931, Germany
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33
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Mechanisms of Autophagy in Metabolic Stress Response. J Mol Biol 2020; 432:28-52. [DOI: 10.1016/j.jmb.2019.09.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 09/06/2019] [Accepted: 09/06/2019] [Indexed: 01/17/2023]
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Agrawal P, Manjithaya R, Surolia N. Autophagy‐related protein
Pf
ATG18 participates in food vacuole dynamics and autophagy‐like pathway in
Plasmodium falciparum. Mol Microbiol 2019; 113:766-782. [DOI: 10.1111/mmi.14441] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 12/17/2019] [Accepted: 12/17/2019] [Indexed: 12/30/2022]
Affiliation(s)
- Palak Agrawal
- Molecular Biology and Genetics Unit Jawaharlal Nehru Centre for Advanced Scientific Research Bangalore India
| | - Ravi Manjithaya
- Molecular Biology and Genetics Unit Jawaharlal Nehru Centre for Advanced Scientific Research Bangalore India
| | - Namita Surolia
- Molecular Biology and Genetics Unit Jawaharlal Nehru Centre for Advanced Scientific Research Bangalore India
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35
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Gobé C, Elzaiat M, Meunier N, André M, Sellem E, Congar P, Jouneau L, Allais-Bonnet A, Naciri I, Passet B, Pailhoux E, Pannetier M. Dual role of DMXL2 in olfactory information transmission and the first wave of spermatogenesis. PLoS Genet 2019; 15:e1007909. [PMID: 30735494 PMCID: PMC6383954 DOI: 10.1371/journal.pgen.1007909] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 02/21/2019] [Accepted: 12/19/2018] [Indexed: 12/29/2022] Open
Abstract
Gonad differentiation is a crucial step conditioning the future fertility of individuals and most of the master genes involved in this process have been investigated in detail. However, transcriptomic analyses of developing gonads from different animal models have revealed that hundreds of genes present sexually dimorphic expression patterns. DMXL2 was one of these genes and its function in mammalian gonads was unknown. We therefore investigated the phenotypes of total and gonad-specific Dmxl2 knockout mouse lines. The total loss-of-function of Dmxl2 was lethal in neonates, with death occurring within 12 hours of birth. Dmxl2-knockout neonates were weak and did not feed. They also presented defects of olfactory information transmission and severe hypoglycemia, suggesting that their premature death might be due to global neuronal and/or metabolic deficiencies. Dmxl2 expression in the gonads increased after birth, during follicle formation in females and spermatogenesis in males. DMXL2 was detected in both the supporting and germinal cells of both sexes. As Dmxl2 loss-of-function was lethal, only limited investigations of the gonads of Dmxl2 KO pups were possible. They revealed no major defects at birth. The gonadal function of Dmxl2 was then assessed by conditional deletions of the gene in gonadal supporting cells, germinal cells, or both. Conditional Dmxl2 ablation in the gonads did not impair fertility in males or females. By contrast, male mice with Dmxl2 deletions, either throughout the testes or exclusively in germ cells, presented a subtle testicular phenotype during the first wave of spermatogenesis that was clearly detectable at puberty. Indeed, Dmxl2 loss-of-function throughout the testes or in germ cells only, led to sperm counts more than 60% lower than normal and defective seminiferous tubule architecture. Transcriptomic and immunohistochemichal analyses on these abnormal testes revealed a deregulation of Sertoli cell phagocytic activity related to germ cell apoptosis augmentation. In conclusion, we show that Dmxl2 exerts its principal function in the testes at the onset of puberty, although its absence does not compromise male fertility in mice.
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Affiliation(s)
- Clara Gobé
- UMR BDR, INRA, ENVA, Université Paris Saclay, Jouy-en-Josas, France
| | - Maëva Elzaiat
- UMR 7592 Institut Jacques Monod, Université Paris Diderot/CNRS, Paris, France
| | - Nicolas Meunier
- NBO, INRA, Université Paris Saclay, Jouy en Josas, France
- Université de Versailles Saint-Quentin en Yvelines, Versailles, France
| | - Marjolaine André
- UMR BDR, INRA, ENVA, Université Paris Saclay, Jouy-en-Josas, France
| | - Eli Sellem
- UMR BDR, INRA, ENVA, Université Paris Saclay, Jouy-en-Josas, France
- R&D Department, ALLICE, Paris, France
| | - Patrice Congar
- NBO, INRA, Université Paris Saclay, Jouy en Josas, France
| | - Luc Jouneau
- UMR BDR, INRA, ENVA, Université Paris Saclay, Jouy-en-Josas, France
| | - Aurélie Allais-Bonnet
- UMR BDR, INRA, ENVA, Université Paris Saclay, Jouy-en-Josas, France
- R&D Department, ALLICE, Paris, France
| | - Ikrame Naciri
- Epigenetics and Cell Fate, Université Paris Diderot, Sorbonne Paris Cité, UMR 7216 CNRS, Paris, France
| | - Bruno Passet
- UMR-GABI 1313, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Eric Pailhoux
- UMR BDR, INRA, ENVA, Université Paris Saclay, Jouy-en-Josas, France
| | - Maëlle Pannetier
- UMR BDR, INRA, ENVA, Université Paris Saclay, Jouy-en-Josas, France
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Osawa T, Alam JM, Noda NN. Membrane-binding domains in autophagy. Chem Phys Lipids 2019; 218:1-9. [DOI: 10.1016/j.chemphyslip.2018.11.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 10/31/2018] [Accepted: 11/07/2018] [Indexed: 02/07/2023]
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Baba M, Tomonaga S, Suzuki M, Gen M, Takeda E, Matsuura A, Kamada Y, Baba N. A nuclear membrane-derived structure associated with Atg8 is involved in the sequestration of selective cargo, the Cvt complex, during autophagosome formation in yeast. Autophagy 2018; 15:423-437. [PMID: 30238844 DOI: 10.1080/15548627.2018.1525475] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Macroautophagy (hereafter autophagy) is a conserved intracellular degradation mechanism required for cell survival. A double-membrane structure, the phagophore, is generated to sequester cytosolic cargos destined for degradation in the vacuole. The mechanism involved in the biogenesis of the phagophore is still an open question. We focused on 4 autophagy-related (Atg) proteins (Atg2, Atg9, Atg14, and Atg18), which are involved in the formation of the phagophore in order to gain a more complete understanding of the membrane dynamics that occur during formation of the autophagosome. The corresponding mutants, while defective in autophagy, nonetheless generate the membrane-bound form of Atg8, allowing us to use this protein as a marker for the nascent autophagosome precursor membrane. Using electron microscopy (EM), we discovered in these atg mutants a novel single-membrane structure (~120 to 150 nm in size). Electron tomography revealed that this structure originates from a part of the nuclear membrane, and we have named it the alphasome. Our data suggest that the alphasome is associated with Atg8, and sequesters selective cargo, the Cvt complex, during autophagy. Abbreviations: 3D: three-dimensional; AB: autophagic body; AP: autophagosome; Atg: autophagy-related; Cvt: cytoplasm-to-vacuole targeting; EM: electron microscopy; IEM: immunoelectron microscopy; L: lipid droplet; N: nucleus; NM: nuclear membrane; PAS: phagophore assembly site; PE: phosphatidylethanolamine; prApe1: precursor aminopeptidase I; rER: rough endoplasmic reticulum; TEM: transmission electron microscopy; V: vacuole; VLP: virus-like particle.
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Affiliation(s)
- Misuzu Baba
- a Research Institute for Science and Technology , Kogakuin University , Hachioji, Tokyo , Japan
| | - Sachihiko Tomonaga
- b Major of Informatics , Graduate School, Kogakuin University , Hachioji, Tokyo , Japan
| | - Masato Suzuki
- b Major of Informatics , Graduate School, Kogakuin University , Hachioji, Tokyo , Japan
| | - Maeda Gen
- b Major of Informatics , Graduate School, Kogakuin University , Hachioji, Tokyo , Japan
| | - Eigo Takeda
- c Department of Nanobiology , Graduate School of Advanced Integration Science, Chiba University , Inage-ku, Chiba , Japan
| | - Akira Matsuura
- c Department of Nanobiology , Graduate School of Advanced Integration Science, Chiba University , Inage-ku, Chiba , Japan.,d Department of Biology , Graduate School of Science, Chiba University , Inage-ku, Chiba , Japan
| | - Yoshiaki Kamada
- e Laboratory of Biological Diversity , National Institute for Basic Biology, and School of Life Science, Graduate School of Advanced Studies , Myodaiji Okazaki, Aichi , Japan
| | - Norio Baba
- a Research Institute for Science and Technology , Kogakuin University , Hachioji, Tokyo , Japan.,b Major of Informatics , Graduate School, Kogakuin University , Hachioji, Tokyo , Japan
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The Atg2-Atg18 complex tethers pre-autophagosomal membranes to the endoplasmic reticulum for autophagosome formation. Proc Natl Acad Sci U S A 2018; 115:10363-10368. [PMID: 30254161 DOI: 10.1073/pnas.1806727115] [Citation(s) in RCA: 193] [Impact Index Per Article: 32.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The biogenesis of double-membrane vesicles called autophagosomes, which sequester and transport intracellular material for degradation in lysosomes or vacuoles, is a central event in autophagy. This process requires a unique set of factors called autophagy-related (Atg) proteins. The Atg proteins assemble to organize the preautophagosomal structure (PAS), at which a cup-shaped membrane, the isolation membrane (or phagophore), forms and expands to become the autophagosome. The molecular mechanism of autophagosome biogenesis remains poorly understood. Previous studies have shown that Atg2 forms a complex with the phosphatidylinositol 3-phosphate (PI3P)-binding protein Atg18 and localizes to the PAS to initiate autophagosome biogenesis; however, the molecular function of Atg2 remains unknown. In this study, we show that Atg2 has two membrane-binding domains in the N- and C-terminal regions and acts as a membrane tether during autophagosome formation in the budding yeast Saccharomyces cerevisiae An amphipathic helix in the C-terminal region binds to membranes and facilitates Atg18 binding to PI3P to target the Atg2-Atg18 complex to the PAS. The N-terminal region of Atg2 is also involved in the membrane binding of this protein but is dispensable for the PAS targeting of the Atg2-Atg18 complex. Our data suggest that this region associates with the endoplasmic reticulum (ER) and is responsible for the formation of the isolation membrane at the PAS. Based on these results, we propose that the Atg2-Atg18 complex tethers the PAS to the ER to initiate membrane expansion during autophagosome formation.
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Insights into autophagosome biogenesis from structural and biochemical analyses of the ATG2A-WIPI4 complex. Proc Natl Acad Sci U S A 2018; 115:E9792-E9801. [PMID: 30185561 DOI: 10.1073/pnas.1811874115] [Citation(s) in RCA: 138] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Autophagy is an enigmatic cellular process in which double-membrane compartments, called "autophagosomes, form de novo adjacent to the endoplasmic reticulum (ER) and package cytoplasmic contents for delivery to lysosomes. Expansion of the precursor membrane phagophore requires autophagy-related 2 (ATG2), which localizes to the PI3P-enriched ER-phagophore junction. We combined single-particle electron microscopy, chemical cross-linking coupled with mass spectrometry, and biochemical analyses to characterize human ATG2A in complex with the PI3P effector WIPI4. ATG2A is a rod-shaped protein that can bridge neighboring vesicles through interactions at each of its tips. WIPI4 binds to one of the tips, enabling the ATG2A-WIPI4 complex to tether a PI3P-containing vesicle to another PI3P-free vesicle. These data suggest that the ATG2A-WIPI4 complex mediates ER-phagophore association and/or tethers vesicles to the ER-phagophore junction, establishing the required organization for phagophore expansion via the transfer of lipid membranes from the ER and/or the vesicles to the phagophore.
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Gao J, Reggiori F, Ungermann C. A novel in vitro assay reveals SNARE topology and the role of Ykt6 in autophagosome fusion with vacuoles. J Cell Biol 2018; 217:3670-3682. [PMID: 30097515 PMCID: PMC6168247 DOI: 10.1083/jcb.201804039] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 06/13/2018] [Accepted: 07/06/2018] [Indexed: 11/22/2022] Open
Abstract
Autophagosome fusion with vacuoles requires a conserved fusion machinery, though the topology remained unclear. Two papers in this issue, Bas et al. and Gao et al., uncover Ykt6 as the required autophagosomal SNARE. Autophagy is a catabolic pathway that delivers intracellular material to the mammalian lysosomes or the yeast and plant vacuoles. The final step in this process is the fusion of autophagosomes with vacuoles, which requires SNARE proteins, the homotypic vacuole fusion and protein sorting tethering complex, the RAB7-like Ypt7 GTPase, and its guanine nucleotide exchange factor, Mon1-Ccz1. Where these different components are located and function during fusion, however, remains to be fully understood. Here, we present a novel in vitro assay to monitor fusion of intact and functional autophagosomes with vacuoles. This process requires ATP, physiological temperature, and the entire fusion machinery to tether and fuse autophagosomes with vacuoles. Importantly, we uncover Ykt6 as the autophagosomal SNARE. Our assay and findings thus provide the tools to dissect autophagosome completion and fusion in a test tube.
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Affiliation(s)
- Jieqiong Gao
- Biochemistry Section, Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Fulvio Reggiori
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Christian Ungermann
- Biochemistry Section, Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany .,Center of Cellular Nanoanalytics Osnabrück (CellNanOs), University of Osnabrück, Osnabrück, Germany
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Gómez-Sánchez R, Rose J, Guimarães R, Mari M, Papinski D, Rieter E, Geerts WJ, Hardenberg R, Kraft C, Ungermann C, Reggiori F. Atg9 establishes Atg2-dependent contact sites between the endoplasmic reticulum and phagophores. J Cell Biol 2018; 217:2743-2763. [PMID: 29848619 PMCID: PMC6080931 DOI: 10.1083/jcb.201710116] [Citation(s) in RCA: 174] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 03/07/2018] [Accepted: 05/02/2018] [Indexed: 11/22/2022] Open
Abstract
The autophagy-related (Atg) proteins play a key role in the formation of autophagosomes, the hallmark of autophagy. The function of the cluster composed by Atg2, Atg18, and transmembrane Atg9 is completely unknown despite their importance in autophagy. In this study, we provide insights into the molecular role of these proteins by identifying and characterizing Atg2 point mutants impaired in Atg9 binding. We show that Atg2 associates to autophagosomal membranes through lipid binding and independently from Atg9. Its interaction with Atg9, however, is key for Atg2 confinement to the growing phagophore extremities and subsequent association of Atg18. Assembly of the Atg9-Atg2-Atg18 complex is important to establish phagophore-endoplasmic reticulum (ER) contact sites. In turn, disruption of the Atg2-Atg9 interaction leads to an aberrant topological distribution of both Atg2 and ER contact sites on forming phagophores, which severely impairs autophagy. Altogether, our data shed light in the interrelationship between Atg9, Atg2, and Atg18 and highlight the possible functional relevance of the phagophore-ER contact sites in phagophore expansion.
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Affiliation(s)
- Rubén Gómez-Sánchez
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Jaqueline Rose
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, Osnabrück, Germany
| | - Rodrigo Guimarães
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
- Department of Cell Biology, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
| | - Muriel Mari
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Daniel Papinski
- Max F. Perutz Laboratories, University of Vienna, Vienna Biocenter, Vienna, Austria
| | - Ester Rieter
- Department of Cell Biology, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
| | - Willie J Geerts
- Biomolecular Imaging, Bijvoet Center, Utrecht University, Utrecht, Netherlands
| | - Ralph Hardenberg
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Claudine Kraft
- Max F. Perutz Laboratories, University of Vienna, Vienna Biocenter, Vienna, Austria
- Institute of Biochemistry and Molecular Biology, Institute of Molecular Medicine and Cell Research, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Christian Ungermann
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, Osnabrück, Germany
| | - Fulvio Reggiori
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
- Department of Cell Biology, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
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Gao J, Langemeyer L, Kümmel D, Reggiori F, Ungermann C. Molecular mechanism to target the endosomal Mon1-Ccz1 GEF complex to the pre-autophagosomal structure. eLife 2018; 7:31145. [PMID: 29446751 PMCID: PMC5841931 DOI: 10.7554/elife.31145] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 02/12/2018] [Indexed: 11/13/2022] Open
Abstract
During autophagy, a newly formed double membrane surrounds its cargo to generate the so-called autophagosome, which then fuses with a lysosome after closure. Previous work implicated that endosomal Rab7/Ypt7 associates to autophagosomes prior to their fusion with lysosomes. Here, we unravel how the Mon1-Ccz1 guanosine exchange factor (GEF) acting upstream of Ypt7 is specifically recruited to the pre-autophagosomal structure under starvation conditions. We find that Mon1-Ccz1 directly binds to Atg8, the yeast homolog of the members of the mammalian LC3 protein family. This requires at least one LIR motif in the Ccz1 C-terminus, which is essential for autophagy but not for endosomal transport. In agreement, only wild-type, but not LIR-mutated Mon1-Ccz1 promotes Atg8-dependent activation of Ypt7. Our data reveal how GEF targeting can specify the fate of a newly formed organelle and provide new insights into the regulation of autophagosome-lysosome fusion. Autophagy is a word derived from the Greek for “self-eating”. It describes a biological process in which a living cell breaks down its own material to release their chemical building blocks that can then be used to make new molecules. Autophagy is often triggered when a cell becomes damaged or when nutrients are in short supply. The hallmark of autophagy is the formation of structures called autophagosomes. These structures capture the cellular material, fuse with other compartments in the cell – namely endosomes in animals and vacuoles in yeast – and then deliver the material inside, ready to be broken down. For an autophagosome to fuse to an endosome or a vacuole, small proteins of the Rab protein family must be located on the surface of the autophagosome. Rab proteins are recruited to this surface by enzymes known as GEFs. However it remains unclear how most GEFs get to the surface of a compartment within the cell to begin with. The Mon1-Ccz1 complex is a GEF that occurs in yeast and animals, including fruit flies and humans. It is found on endosomes, and was recently shown to also localize to autophagosomes. Now, Gao et al. report that, in yeast, the Mon1-Ccz1 complex binds directly to a protein named Atg8. This protein is anchored on to the surface of autophagosomes, and is closely related to other proteins in animal cells. Gao et al. discovered that this specific GEF binds to Atg8 via at least one binding site on its Ccz1 component. This binding site is only needed for the GEF to localize to the autophagosomes; the Mon1-Czz1 complex can still bind to endosomes without it. Blocking the GEF from binding to Atg8 stopped the autophagosomes from fusing with vacuoles. These findings reveal how a GEF can be targeted to two distinct compartments in the cell: endosomes and autophagosomes. Further work is now needed to understand how this process is regulated by the availability of nutrients or damage to the cell, to ensure that autophagy is only triggered under the right conditions. Also, because cancer cells often rely on autophagy to survive, the molecules that regulate this process could represent possible targets for new anticancer drugs.
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Affiliation(s)
- Jieqiong Gao
- Biochemistry Section, Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Lars Langemeyer
- Biochemistry Section, Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Daniel Kümmel
- Structural Biology Section, Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Fulvio Reggiori
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Christian Ungermann
- Biochemistry Section, Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
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43
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Tamura N, Nishimura T, Sakamaki Y, Koyama-Honda I, Yamamoto H, Mizushima N. Differential requirement for ATG2A domains for localization to autophagic membranes and lipid droplets. FEBS Lett 2017; 591:3819-3830. [DOI: 10.1002/1873-3468.12901] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 10/23/2017] [Accepted: 10/30/2017] [Indexed: 01/05/2023]
Affiliation(s)
- Norito Tamura
- Department of Biochemistry and Molecular Biology; Graduate School and Faculty of Medicine; The University of Tokyo; Japan
- Department of Developmental and Regenerative Biology; Medical Research Institute; Tokyo Medical and Dental University; Japan
| | - Taki Nishimura
- Department of Biochemistry and Molecular Biology; Graduate School and Faculty of Medicine; The University of Tokyo; Japan
| | - Yuriko Sakamaki
- Microscopy Research Support Unit Research Core; Tokyo Medical and Dental University; Japan
| | - Ikuko Koyama-Honda
- Department of Biochemistry and Molecular Biology; Graduate School and Faculty of Medicine; The University of Tokyo; Japan
| | - Hayashi Yamamoto
- Department of Biochemistry and Molecular Biology; Graduate School and Faculty of Medicine; The University of Tokyo; Japan
| | - Noboru Mizushima
- Department of Biochemistry and Molecular Biology; Graduate School and Faculty of Medicine; The University of Tokyo; Japan
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Scacioc A, Schmidt C, Hofmann T, Urlaub H, Kühnel K, Pérez-Lara Á. Structure based biophysical characterization of the PROPPIN Atg18 shows Atg18 oligomerization upon membrane binding. Sci Rep 2017; 7:14008. [PMID: 29070817 PMCID: PMC5656675 DOI: 10.1038/s41598-017-14337-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 09/19/2017] [Indexed: 11/29/2022] Open
Abstract
PROPPINs (β-propellers that bind polyphosphoinositides) are PtdIns3P and PtdIns(3,5)P2 binding autophagy related proteins. They contain two phosphatidylinositolphosphate (PIP) binding sites and a conserved FRRG motif is essential for PIP binding. Here we present the 2.0 Å resolution crystal structure of the PROPPIN Atg18 from Pichia angusta. We designed cysteine mutants for labelling with the fluorescence dyes to probe the distances of the mutants to the membrane. These measurements support a model for PROPPIN-membrane binding, where the PROPPIN sits in a perpendicular or slightly tilted orientation on the membrane. Stopped-flow measurements suggest that initial PROPPIN-membrane binding is driven by non-specific PIP interactions. The FRRG motif then retains the protein in the membrane by binding two PIP molecules as evident by a lower dissociation rate for Atg18 in comparison with its PIP binding deficient FTTG mutant. We demonstrate that the amine-specific cross-linker Bis(sulfosuccinimidyl)suberate (BS3), which is used for protein-protein cross-linking can also be applied for cross-linking proteins and phosphatidylethanolamine (PE). Cross-linking experiments with liposome bound Atg18 yielded several PE cross-linked peptides. We also observed intermolecular cross-linked peptides, which indicated Atg18 oligomerization. FRET-based stopped-flow measurements revealed that Atg18 rapidly oligomerizes upon membrane binding while it is mainly monomeric in solution.
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Affiliation(s)
- Andreea Scacioc
- Research Group Autophagy, Max-Planck-Institute for Biophysical Chemistry, Am Faßberg 11, 37077, Göttingen, Germany
| | - Carla Schmidt
- Interdisciplinary research center HALOmem, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120, Halle, Germany. .,Bioanalytical Mass Spectrometry Group, Max-Planck-Institute for Biophysical Chemistry, Am Faßberg 11, 37077, Göttingen, Germany.
| | - Tommy Hofmann
- Interdisciplinary research center HALOmem, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120, Halle, Germany
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry Group, Max-Planck-Institute for Biophysical Chemistry, Am Faßberg 11, 37077, Göttingen, Germany.,Bioanalytics Group, University Medical Center Göttingen, Robert-Koch-Strasse 40, 37075, Göttingen, Germany
| | - Karin Kühnel
- Research Group Autophagy, Max-Planck-Institute for Biophysical Chemistry, Am Faßberg 11, 37077, Göttingen, Germany. .,Nature Communications, 4 Crinan Street, London, N1 9XW, United Kingdom.
| | - Ángel Pérez-Lara
- Department of Neurobiology, Max-Planck-Institute for Biophysical Chemistry, Am Faßberg 11, 37077, Göttingen, Germany.
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Zheng JX, Li Y, Ding YH, Liu JJ, Zhang MJ, Dong MQ, Wang HW, Yu L. Architecture of the ATG2B-WDR45 complex and an aromatic Y/HF motif crucial for complex formation. Autophagy 2017; 13:1870-1883. [PMID: 28820312 DOI: 10.1080/15548627.2017.1359381] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
PtdIns3P signaling is critical for dynamic membrane remodeling during autophagosome formation. Proteins in the Atg18/WIPI family are PtdIns3P-binding effectors which can form complexes with proteins in the Atg2 family, and both families are essential for macroautophagy/autophagy. However, little is known about the biophysical properties and biological functions of the Atg2-Atg18/WIPI complex as a whole. Here, we demonstrate that an ortholog of yeast Atg18, mammalian WDR45/WIPI4 has a stronger binding capacity for mammalian ATG2A or ATG2B than the other 3 WIPIs. We purified the full-length Rattus norvegicus ATG2B and found that it could bind to liposomes independently of PtdIns3P or WDR45. We also purified the ATG2B-WDR45 complex and then performed 3-dimensional reconstruction of the complex by single-particle electron microscopy, which revealed a club-shaped heterodimer with an approximate length of 22 nm. Furthermore, we performed cross-linking mass spectrometry and identified a set of highly cross-linked intermolecular and intramolecular lysine pairs. Finally, based on the cross-linking data followed by bioinformatics and mutagenesis analysis, we determined the conserved aromatic H/YF motif in the C terminus of ATG2A and ATG2B that is crucial for complex formation.
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Affiliation(s)
- Jing-Xiang Zheng
- a State Key Laboratory of Membrane Biology , Tsinghua University-Peking University Joint Center for Life Sciences, School of Life Sciences, Tsinghua University , Beijing , China.,b Joint Graduate Program of Peking-Tsinghua-National Institute of Biological Science , Tsinghua University , Beijing , China
| | - Yan Li
- c Ministry of Education Key Laboratory of Protein Sciences , Tsinghua-Peking Joint Center for Life Sciences , Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing , China
| | - Yue-He Ding
- d National Institute of Biological Sciences , Beijing , China
| | - Jun-Jie Liu
- b Joint Graduate Program of Peking-Tsinghua-National Institute of Biological Science , Tsinghua University , Beijing , China.,c Ministry of Education Key Laboratory of Protein Sciences , Tsinghua-Peking Joint Center for Life Sciences , Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing , China
| | - Mei-Jun Zhang
- d National Institute of Biological Sciences , Beijing , China
| | - Meng-Qiu Dong
- d National Institute of Biological Sciences , Beijing , China
| | - Hong-Wei Wang
- c Ministry of Education Key Laboratory of Protein Sciences , Tsinghua-Peking Joint Center for Life Sciences , Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing , China
| | - Li Yu
- a State Key Laboratory of Membrane Biology , Tsinghua University-Peking University Joint Center for Life Sciences, School of Life Sciences, Tsinghua University , Beijing , China
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Rzepnikowska W, Flis K, Kaminska J, Grynberg M, Urbanek A, Ayscough KR, Zoladek T. Amino acid substitution equivalent to human chorea-acanthocytosis I2771R in yeast Vps13 protein affects its binding to phosphatidylinositol 3-phosphate. Hum Mol Genet 2017; 26:1497-1510. [PMID: 28334785 PMCID: PMC5393151 DOI: 10.1093/hmg/ddx054] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 02/09/2017] [Indexed: 12/16/2022] Open
Abstract
The rare human disorder chorea-acanthocytosis (ChAc) is caused by mutations in hVPS13A gene. The hVps13A protein interacts with actin and regulates the level of phosphatidylinositol 4-phosphate (PI4P) in the membranes of neuronal cells. Yeast Vps13 is involved in vacuolar protein transport and, like hVps13A, participates in PI4P metabolism. Vps13 proteins are conserved in eukaryotes, but their molecular function remains unknown. One of the mutations found in ChAc patients causes amino acids substitution I2771R which affects the localization of hVps13A in skeletal muscles. To dissect the mechanism of pathogenesis of I2771R, we created and analyzed a yeast strain carrying the equivalent mutation. Here we show that in yeast, substitution I2749R causes dysfunction of Vps13 protein in endocytosis and vacuolar transport, although the level of the protein is not affected, suggesting loss of function. We also show that Vps13, like hVps13A, influences actin cytoskeleton organization and binds actin in immunoprecipitation experiments. Vps13-I2749R binds actin, but does not function in the actin cytoskeleton organization. Moreover, we show that Vps13 binds phospholipids, especially phosphatidylinositol 3-phosphate (PI3P), via its SHR_BD and APT1 domains. Substitution I2749R attenuates this ability. Finally, the localization of Vps13-GFP is altered when cellular levels of PI3P are decreased indicating its trafficking within the endosomal membrane system. These results suggest that PI3P regulates the functioning of Vps13, both in protein trafficking and actin cytoskeleton organization. Attenuation of PI3P-binding ability in the mutant hVps13A protein may be one of the reasons for its mislocalization and disrupted function in cells of patients suffering from ChAc.
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Affiliation(s)
- Weronika Rzepnikowska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland
| | - Krzysztof Flis
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland
| | - Joanna Kaminska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland
| | - Marcin Grynberg
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland
| | - Agnieszka Urbanek
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, UK
| | - Kathryn R Ayscough
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, UK
| | - Teresa Zoladek
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland
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Hasegawa J, Strunk BS, Weisman LS. PI5P and PI(3,5)P 2: Minor, but Essential Phosphoinositides. Cell Struct Funct 2017; 42:49-60. [PMID: 28302928 DOI: 10.1247/csf.17003] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
In most eukaryotes, phosphoinositides (PIs) have crucial roles in multiple cellular functions. Although the cellular levels of phosphatidylinositol 5-phosphate (PI5P) and phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2) are extremely low relative to some other PIs, emerging evidence demonstrates that both lipids are crucial for the endocytic pathway, intracellular signaling, and adaptation to stress. Mutations that causes defects in the biosynthesis of PI5P and PI(3,5)P2 are linked to human diseases including neurodegenerative disorders. Here, we review recent findings on cellular roles of PI5P and PI(3,5)P2, as well as the pathophysiological importance of these lipids.Key words: Phosphoinositides, Membrane trafficking, Endocytosis, Vacuoles/Lysosomes, Fab1/PIKfyve.
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Keller CW, Lünemann JD. Autophagy and Autophagy-Related Proteins in CNS Autoimmunity. Front Immunol 2017; 8:165. [PMID: 28289410 PMCID: PMC5326760 DOI: 10.3389/fimmu.2017.00165] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 02/02/2017] [Indexed: 12/13/2022] Open
Abstract
Autophagy comprises a heterogeneous group of cellular pathways that enables eukaryotic cells to deliver cytoplasmic constituents for lysosomal degradation, to recycle nutrients, and to survive during starvation. In addition to these primordial functions, autophagy has emerged as a key mechanism in orchestrating innate and adaptive immune responses and to shape CD4+ T cell immunity through delivery of peptides to major histocompatibility complex (MHC) class II-containing compartments (MIICs). Individual autophagy proteins additionally modulate expression of MHC class I molecules for CD8+ T cell activation. The emergence and expansion of autoreactive CD4+ and CD8+ T cells are considered to play a key role in the pathogenesis of multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis. Expression of the essential autophagy-related protein 5 (Atg5), which supports T lymphocyte survival and proliferation, is increased in T cells isolated from blood or brain tissues from patients with relapsing-remitting MS. Whether Atgs contribute to the activation of autoreactive T cells through autophagy-mediated antigen presentation is incompletely understood. Here, we discuss the complex functions of autophagy proteins and pathways in regulating T cell immunity and its potential role in the development and progression of MS.
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Affiliation(s)
- Christian W Keller
- Institute of Experimental Immunology, Laboratory of Neuroinflammation, University of Zürich , Zürich , Switzerland
| | - Jan D Lünemann
- Institute of Experimental Immunology, Laboratory of Neuroinflammation, University of Zürich, Zürich, Switzerland; Department of Neurology, University Hospital Zürich, Zürich, Switzerland
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Gómez-Sánchez R, Sánchez-Wandelmer J, Reggiori F. Monitoring the Formation of Autophagosomal Precursor Structures in Yeast Saccharomyces cerevisiae. Methods Enzymol 2017; 588:323-365. [DOI: 10.1016/bs.mie.2016.09.085] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Suzuki H, Osawa T, Fujioka Y, Noda NN. Structural biology of the core autophagy machinery. Curr Opin Struct Biol 2016; 43:10-17. [PMID: 27723509 DOI: 10.1016/j.sbi.2016.09.010] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Revised: 09/13/2016] [Accepted: 09/21/2016] [Indexed: 02/08/2023]
Abstract
In autophagy, which is an intracellular degradation system that is conserved among eukaryotes, degradation targets are sequestered through the de novo synthesis of a double-membrane organelle, the autophagosome, which delivers them to the lysosomes for degradation. The core autophagy machinery comprising 18 autophagy-related (Atg) proteins in yeast plays an essential role in autophagosome formation; however, the molecular role of each Atg factor and the mechanism of autophagosome formation remain elusive. Recent years have seen remarkable progress in structural biological studies on the core autophagy machinery, opening new avenues for autophagy research. This review summarizes recent advances in structural biological and mechanistic studies on the core autophagy machinery and discusses the molecular mechanisms of autophagosome formation.
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Affiliation(s)
- Hironori Suzuki
- Institute of Microbial Chemistry, Microbial Chemistry Research Foundation, 3-14-23 Kamiosaki, Shinagawa-ku, Tokyo 141-0021, Japan
| | - Takuo Osawa
- Institute of Microbial Chemistry, Microbial Chemistry Research Foundation, 3-14-23 Kamiosaki, Shinagawa-ku, Tokyo 141-0021, Japan
| | - Yuko Fujioka
- Institute of Microbial Chemistry, Microbial Chemistry Research Foundation, 3-14-23 Kamiosaki, Shinagawa-ku, Tokyo 141-0021, Japan
| | - Nobuo N Noda
- Institute of Microbial Chemistry, Microbial Chemistry Research Foundation, 3-14-23 Kamiosaki, Shinagawa-ku, Tokyo 141-0021, Japan.
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