1
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Chung T, Choi YE, Song K, Jung H. How coat proteins shape autophagy in plant cells. PLANT PHYSIOLOGY 2024:kiae426. [PMID: 39259569 DOI: 10.1093/plphys/kiae426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2024] [Accepted: 08/07/2024] [Indexed: 09/13/2024]
Abstract
Autophagy is a membrane trafficking pathway through which eukaryotic cells target their own cytoplasmic constituents for degradation in the lytic compartment. Proper biogenesis of autophagic organelles requires a conserved set of autophagy-related (ATG) proteins and their interacting factors, such as signalling phospholipid phosphatidylinositol 3-phosphate (PI3P) and coat complex II (COPII). The COPII machinery, which was originally identified as a membrane coat involved in the formation of vesicles budding from the endoplasmic reticulum, contributes to the initiation of autophagic membrane formation in yeast, metazoan, and plant cells; however, the exact mechanisms remain elusive. Recent studies using the plant model species Arabidopsis thaliana have revealed that plant-specific PI3P effectors are involved in autophagy. The PI3P effector FYVE2 interacts with the conserved PI3P effector ATG18 and with COPII components, indicating an additional role for the COPII machinery in the later stages of autophagosome biogenesis. In this Update, we examined recent research on plant autophagosome biogenesis and proposed working models on the functions of the COPII machinery in autophagy, including its potential roles in stabilizing membrane curvature and sealing the phagophore.
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Affiliation(s)
- Taijoon Chung
- Department of Biological Sciences, Pusan National University, Busan, 46241, Republic of Korea
- Institute of Systems Biology, Pusan National University, Busan, 46241, Republic of Korea
| | - Ye Eun Choi
- Department of Biological Sciences, Pusan National University, Busan, 46241, Republic of Korea
| | - Kyoungjun Song
- Department of Biological Sciences, Pusan National University, Busan, 46241, Republic of Korea
| | - Hyera Jung
- Department of Biological Sciences, Pusan National University, Busan, 46241, Republic of Korea
- Institute of Systems Biology, Pusan National University, Busan, 46241, Republic of Korea
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2
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Li X, Zheng J, Su J, Wang L, Luan L, Wang T, Bai F, Zhong Q, Gong Q. Myotubularin 2 interacts with SEC23A and negatively regulates autophagy at ER exit sites in Arabidopsis. Autophagy 2024:1-19. [PMID: 39177202 DOI: 10.1080/15548627.2024.2394302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 08/11/2024] [Accepted: 08/15/2024] [Indexed: 08/24/2024] Open
Abstract
Starvation- or stress-induced phosphatidylinositol 3-phosphate (PtdIns3P/PI3P) production at the endoplasmic reticulum (ER) subdomains organizes phagophore assembly and autophagosome formation. Coat protein complex II (COPII) vesicles budding from ER exit site (ERES) also contribute to autophagosome formation. Whether any PtdIns3P phosphatase functions at ERES to inhibit macroautophagy/autophagy is unknown. Here we report Myotubularin 2 (MTM2) of Arabidopsis as a PtdIns3P phosphatase that localizes to ERES and negatively regulates autophagy. MTM2 binds PtdIns3P with its PH-GRAM domain in vitro and acts toward PtdIns3P in vivo. Transiently expressed MTM2 colocalizes with ATG14b, a subunit of the phosphatidylinositol 3-kinase (PtdIns3K) complex, and overexpression of MTM2 blocks autophagic flux and causes over-accumulation of ATG18a, ATG5, and ATG8a. The mtm2 mutant has higher levels of autophagy and is more tolerant to starvation, whereas MTM2 overexpression leads to reduced autophagy and sensitivity to starvation. The phenotypes of mtm2 are suppressed by ATG2 mutation, suggesting that MTM2 acts upstream of ATG2. Importantly, MTM2 does not affect the endosomal functions of PtdIns3P. Instead, MTM2 specifically colocalizes with COPII coat proteins and is cradled by the ERES-defining protein SEC16. MTM2 interacts with SEC23A with its phosphatase domain and inhibits COPII-mediated protein secretion. Finally, a role for MTM2 in salt stress response is uncovered. mtm2 resembles the halophyte Thellungiella salsuginea in its efficient vacuolar compartmentation of Na+, maintenance of chloroplast integrity, and timely regulation of autophagy-related genes. Our findings reveal a balance between PtdIns3P synthesis and turnover in autophagosome formation, and provide a new link between autophagy and COPII function.Abbreviations: ATG: autophagy related; BFA: brefeldin A; BiFC: bimolecular fluorescence complementation; CHX: cycloheximide; ConA: concanamycin A; COPII: coat protein complex II; ER: endoplasmic reticulum; ERES: ER exit site; MS: Murashige and Skoog; MTM: myotubularin; MVB: multivesicular body; PAS: phagophore assembly site; PI: phosphoinositide; TEM: transmission electron microscopy; WT: wild-type.
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Affiliation(s)
- Xinjing Li
- State Key Laboratory of Microbial Metabolism & Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, P. R. China
| | - Jing Zheng
- Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, Tianjin, P. R. China
| | - Jing Su
- Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, Tianjin, P. R. China
| | - Lin Wang
- Shanghai Institute for Advanced Immunochemical Studies, School of Life Science and Technology, ShanghaiTech University, Shanghai, P. R. China
| | - Lin Luan
- Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, Tianjin, P. R. China
| | - Taotao Wang
- State Key Laboratory of Microbial Metabolism & Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, P. R. China
| | - Fang Bai
- Shanghai Institute for Advanced Immunochemical Studies, School of Life Science and Technology, ShanghaiTech University, Shanghai, P. R. China
| | - Qing Zhong
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, P. R. China
| | - Qingqiu Gong
- State Key Laboratory of Microbial Metabolism & Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, P. R. China
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3
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Zhuang X, Li B, Jiang L. Autophagosome biogenesis and organelle homeostasis in plant cells. THE PLANT CELL 2024; 36:3009-3024. [PMID: 38536783 PMCID: PMC11371174 DOI: 10.1093/plcell/koae099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 02/23/2024] [Indexed: 09/05/2024]
Abstract
Autophagy is one of the major highly inducible degradation processes in response to plant developmental and environmental signals. In response to different stimuli, cellular materials, including proteins and organelles, can be sequestered into a double membrane autophagosome structure either selectively or nonselectively. The formation of an autophagosome as well as its delivery into the vacuole involves complex and dynamic membrane processes. The identification and characterization of the conserved autophagy-related (ATG) proteins and their related regulators have greatly advanced our understanding of the molecular mechanism underlying autophagosome biogenesis and function in plant cells. Autophagosome biogenesis is tightly regulated by the coordination of multiple ATG and non-ATG proteins and by selective cargo recruitment. This review updates our current knowledge of autophagosome biogenesis, with special emphasis on the core molecular machinery that drives autophagosome formation and autophagosome-organelle interactions under abiotic stress conditions.
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Affiliation(s)
- Xiaohong Zhuang
- School of Life Sciences, Centre for Cell and Developmental Biology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
- State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Baiying Li
- State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
- Department of Biology, Hong Kong Baptist University, Hong Kong SAR, China
| | - Liwen Jiang
- School of Life Sciences, Centre for Cell and Developmental Biology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
- State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
- Institute of Plant Molecular Biology and Agricultural Biotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong, China
- CUHK Shenzhen Research Institute, Shenzhen 518057, China
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4
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Di Rienzo M, Romagnoli A, Refolo G, Vescovo T, Ciccosanti F, Zuchegna C, Lozzi F, Occhigrossi L, Piacentini M, Fimia GM. Role of AMBRA1 in mitophagy regulation: emerging evidence in aging-related diseases. Autophagy 2024:1-14. [PMID: 39113560 DOI: 10.1080/15548627.2024.2389474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Revised: 07/25/2024] [Accepted: 08/02/2024] [Indexed: 09/03/2024] Open
Abstract
Aging is a gradual and irreversible physiological process that significantly increases the risks of developing a variety of pathologies, including neurodegenerative, cardiovascular, metabolic, musculoskeletal, and immune system diseases. Mitochondria are the energy-producing organelles, and their proper functioning is crucial for overall cellular health. Over time, mitochondrial function declines causing an increased release of harmful reactive oxygen species (ROS) and DNA, which leads to oxidative stress, inflammation and cellular damage, common features associated with various age-related pathologies. The impairment of mitophagy, the selective removal of damaged or dysfunctional mitochondria by autophagy, is relevant to the development and progression of age-related diseases. The molecular mechanisms that regulates mitophagy levels in aging remain largely uncharacterized. AMBRA1 is an intrinsically disordered scaffold protein with a unique property of regulating the activity of both proliferation and autophagy core machineries. While the role of AMBRA1 during embryonic development and neoplastic transformation has been extensively investigated, its functions in post-mitotic cells of adult tissues have been limited due to the embryonic lethality caused by AMBRA1 deficiency. Recently, a key role of AMBRA1 in selectively regulating mitophagy in post-mitotic cells has emerged. Here we summarize and discuss these results with the aim of providing a comprehensive view of the mitochondrial roles of AMBRA1, and how defective activity of AMBRA1 has been functionally linked to mitophagy alterations observed in age-related degenerative disorders, including muscular dystrophy/sarcopenia, Parkinson diseases, Alzheimer diseases and age-related macular degeneration.Abbreviations: AD: Alzheimer disease; AMD: age-related macular degeneration; AMBRA1: autophagy and beclin 1 regulator 1; APOE4: apolipoprotein E4; ATAD3A: ATPase family AAA domain containing 3A; ATG: autophagy related; BCL2: BCL2 apoptosis regulator; BH3: BCL2-homology-3; BNIP3L/NIX: BCL2 interacting protein 3 like; CDK: cyclin dependent kinase; CHUK/IKKα: component of inhibitor of nuclear factor kappa B kinase complex; CRL2: CUL2-RING ubiquitin ligase; DDB1: damage specific DNA binding protein 1; ER: endoplasmic reticulum; FOXO: forkhead box O; FUNDC1: FUN14 domain containing 1; GBA/β-glucocerebrosidase: glucosylceramidase beta; HUWE1: HECT, UBA and WWE domain containing E3 ubiquitin protein ligase 1; IDR: intrinsically disordered region; LIR: LC3-interacting region; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MAVS: mitochondrial antiviral signaling protein; MCL1: MCL1 apoptosis regulator, BCL2 family member; MFN2: mitofusin 2; MTOR: mechanistic target of rapamycin kinase; MSA: multiple system atrophy; MYC: MYC proto-oncogene, bHLH transcription factor; NUMA1: nuclear mitotic apparatus protein 1; OMM; mitochondria outer membrane; PD: Parkinson disease; PHB2: prohibitin 2; PINK1: PTEN induced kinase 1; PIK3C3/VPS34: phosphatidylinositol 3-kinase catalytic subunit type 3; PTK2/FAK: protein tyrosine kinase 2; ROS: reactive oxygen species; RPE: retinal pigment epithelium; SAD: sporadic AD; SOCS3: suppressor of cytokine signaling 3; SRC, SRC proto-oncogene, non-receptor tyrosine kinase; STAT3: signal transducer and activator of transcription 3; STING1: stimulator of interferon response cGAMP interactor 1; SQSTM1/p62: sequestosome 1; TBK1: TANK binding kinase 1; TGFB/TGFβ: transforming growth factor beta; TOMM: translocase of outer mitochondrial membrane; TRAF6: TNF receptor associated factor 6; TRIM32: tripartite motif containing 32; ULK1: unc-51 like autophagy activating kinase 1.
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Affiliation(s)
- Martina Di Rienzo
- Department of Epidemiology, Preclinical Research and Advanced Diagnostics, National Institute for Infectious Diseases IRCCS 'L. Spallanzani', Rome, Italy
| | - Alessandra Romagnoli
- Department of Epidemiology, Preclinical Research and Advanced Diagnostics, National Institute for Infectious Diseases IRCCS 'L. Spallanzani', Rome, Italy
| | - Giulia Refolo
- Department of Epidemiology, Preclinical Research and Advanced Diagnostics, National Institute for Infectious Diseases IRCCS 'L. Spallanzani', Rome, Italy
| | - Tiziana Vescovo
- Department of Epidemiology, Preclinical Research and Advanced Diagnostics, National Institute for Infectious Diseases IRCCS 'L. Spallanzani', Rome, Italy
| | - Fabiola Ciccosanti
- Department of Epidemiology, Preclinical Research and Advanced Diagnostics, National Institute for Infectious Diseases IRCCS 'L. Spallanzani', Rome, Italy
| | - Candida Zuchegna
- Department of Epidemiology, Preclinical Research and Advanced Diagnostics, National Institute for Infectious Diseases IRCCS 'L. Spallanzani', Rome, Italy
| | - Francesca Lozzi
- Department of Epidemiology, Preclinical Research and Advanced Diagnostics, National Institute for Infectious Diseases IRCCS 'L. Spallanzani', Rome, Italy
| | - Luca Occhigrossi
- Department of Epidemiology, Preclinical Research and Advanced Diagnostics, National Institute for Infectious Diseases IRCCS 'L. Spallanzani', Rome, Italy
- Department of Molecular Medicine, University of Rome "La Sapienza", Rome, Italy
| | - Mauro Piacentini
- Department of Epidemiology, Preclinical Research and Advanced Diagnostics, National Institute for Infectious Diseases IRCCS 'L. Spallanzani', Rome, Italy
- Department of Biology, University of Rome 'Tor Vergata', Rome, Italy
| | - Gian Maria Fimia
- Department of Epidemiology, Preclinical Research and Advanced Diagnostics, National Institute for Infectious Diseases IRCCS 'L. Spallanzani', Rome, Italy
- Department of Molecular Medicine, University of Rome "La Sapienza", Rome, Italy
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5
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Mohan J, Moparthi SB, Girard-Blanc C, Campisi D, Blanchard S, Nugues C, Rama S, Salles A, Pénard E, Vassilopoulos S, Wollert T. ATG16L1 induces the formation of phagophore-like membrane cups. Nat Struct Mol Biol 2024; 31:1448-1459. [PMID: 38834913 DOI: 10.1038/s41594-024-01300-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 03/28/2024] [Indexed: 06/06/2024]
Abstract
The hallmark of non-selective autophagy is the formation of cup-shaped phagophores that capture bulk cytoplasm. The process is accompanied by the conjugation of LC3B to phagophores by an E3 ligase complex comprising ATG12-ATG5 and ATG16L1. Here we combined two complementary reconstitution approaches to reveal the function of LC3B and its ligase complex during phagophore expansion. We found that LC3B forms together with ATG12-ATG5-ATG16L1 a membrane coat that remodels flat membranes into cups that closely resemble phagophores. Mechanistically, we revealed that cup formation strictly depends on a close collaboration between LC3B and ATG16L1. Moreover, only LC3B, but no other member of the ATG8 protein family, promotes cup formation. ATG16L1 truncates that lacked the C-terminal membrane binding domain catalyzed LC3B lipidation but failed to assemble coats, did not promote cup formation and inhibited the biogenesis of non-selective autophagosomes. Our results thus demonstrate that ATG16L1 and LC3B induce and stabilize the characteristic cup-like shape of phagophores.
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Affiliation(s)
- Jagan Mohan
- Membrane Biochemistry and Transport, Institut Pasteur, Université de Paris, Paris, France
| | - Satish B Moparthi
- Membrane Biochemistry and Transport, Institut Pasteur, Université de Paris, Paris, France
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Association Institut de Myologie, Centre de Recherche en Myologie, Paris, France
| | - Christine Girard-Blanc
- Membrane Biochemistry and Transport, Institut Pasteur, Université de Paris, Paris, France
| | - Daniele Campisi
- Membrane Biochemistry and Transport, Institut Pasteur, Université de Paris, Paris, France
| | - Stéphane Blanchard
- Membrane Biochemistry and Transport, Institut Pasteur, Université de Paris, Paris, France
| | - Charlotte Nugues
- Membrane Biochemistry and Transport, Institut Pasteur, Université de Paris, Paris, France
| | - Sowmya Rama
- Membrane Biochemistry and Transport, Institut Pasteur, Université de Paris, Paris, France
| | - Audrey Salles
- Unit of Technology and Service Photonic BioImaging (UTechS PBI), C2RT, Institut Pasteur, Université de Paris, Paris, France
| | - Esthel Pénard
- Ultrastructural BioImaging Core Facility (UBI), C2RT, Institut Pasteur, Université Paris Cité, Paris, France
| | - Stéphane Vassilopoulos
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Association Institut de Myologie, Centre de Recherche en Myologie, Paris, France.
| | - Thomas Wollert
- Membrane Biochemistry and Transport, Institut Pasteur, Université de Paris, Paris, France.
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6
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Sankar DS, Kaeser-Pebernard S, Vionnet C, Favre S, de Oliveira Marchioro L, Pillet B, Zhou J, Stumpe M, Kovacs WJ, Kressler D, Antonioli M, Fimia GM, Dengjel J. The ULK1 effector BAG2 regulates autophagy initiation by modulating AMBRA1 localization. Cell Rep 2024; 43:114689. [PMID: 39207901 DOI: 10.1016/j.celrep.2024.114689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 06/15/2024] [Accepted: 08/12/2024] [Indexed: 09/04/2024] Open
Abstract
Autophagy initiation is regulated by the ULK1 kinase complex. To gain insights into functions of the holo-complex, we generated a deep interactome by combining affinity purification- and proximity labeling-mass spectrometry of all four complex members: ULK1, ATG13, ATG101, and RB1CC1/FIP200. Under starvation conditions, the ULK1 complex interacts with several protein and lipid kinases and phosphatases, implying the formation of a signalosome. Interestingly, several selective autophagy receptors also interact with ULK1, indicating the activation of selective autophagy pathways by nutrient starvation. One effector of the ULK1 complex is the HSC/HSP70 co-chaperone BAG2, which regulates the subcellular localization of the VPS34 lipid kinase complex member AMBRA1. Depending on the nutritional status, BAG2 has opposing roles. In growth conditions, the unphosphorylated form of BAG2 sequesters AMBRA1, attenuating autophagy induction. In starvation conditions, ULK1 phosphorylates BAG2 on Ser31, which supports the recruitment of AMBRA1 to the ER membrane, positively affecting autophagy.
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Affiliation(s)
| | | | - Christine Vionnet
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Sebastian Favre
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Lais de Oliveira Marchioro
- Department of Epidemiology, Preclinical Research and Advanced Diagnostics, National Institute for Infectious Diseases IRCCS "L. Spallanzani", 00149 Rome, Italy; Department of Pharmacology, Federal University of São Paulo (UNIFESP), São Paulo CEP 05508-000, Brazil
| | - Benjamin Pillet
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Jianwen Zhou
- Institute of Molecular Health Sciences, ETH Zürich, 8093 Zürich, Switzerland
| | - Michael Stumpe
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Werner Josef Kovacs
- Institute of Molecular Health Sciences, ETH Zürich, 8093 Zürich, Switzerland
| | - Dieter Kressler
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Manuela Antonioli
- Department of Epidemiology, Preclinical Research and Advanced Diagnostics, National Institute for Infectious Diseases IRCCS "L. Spallanzani", 00149 Rome, Italy; Department of Biology, University of Rome "Tor Vergata", 00133 Rome, Italy
| | - Gian Maria Fimia
- Department of Epidemiology, Preclinical Research and Advanced Diagnostics, National Institute for Infectious Diseases IRCCS "L. Spallanzani", 00149 Rome, Italy; Department of Molecular Medicine, University of Rome "Sapienza", 00185 Rome, Italy
| | - Jӧrn Dengjel
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland.
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7
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Wang Y, Dahmane S, Ti R, Mai X, Zhu L, Carlson LA, Stjepanovic G. Structural basis for lipid transfer by the ATG2A-ATG9A complex. Nat Struct Mol Biol 2024:10.1038/s41594-024-01376-6. [PMID: 39174844 DOI: 10.1038/s41594-024-01376-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 07/23/2024] [Indexed: 08/24/2024]
Abstract
Autophagy is characterized by the formation of double-membrane vesicles called autophagosomes. Autophagy-related proteins (ATGs) 2A and 9A have an essential role in autophagy by mediating lipid transfer and re-equilibration between membranes for autophagosome formation. Here we report the cryo-electron microscopy structures of human ATG2A in complex with WD-repeat protein interacting with phosphoinositides 4 (WIPI4) at 3.2 Å and the ATG2A-WIPI4-ATG9A complex at 7 Å global resolution. On the basis of molecular dynamics simulations, we propose a mechanism of lipid extraction from the donor membranes. Our analysis revealed 3:1 stoichiometry of the ATG9A-ATG2A complex, directly aligning the ATG9A lateral pore with ATG2A lipid transfer cavity, and an interaction of the ATG9A trimer with both the N-terminal and the C-terminal tip of rod-shaped ATG2A. Cryo-electron tomography of ATG2A liposome-binding states showed that ATG2A tethers lipid vesicles at different orientations. In summary, this study provides a molecular basis for the growth of the phagophore membrane and lends structural insights into spatially coupled lipid transport and re-equilibration during autophagosome formation.
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Affiliation(s)
- Yang Wang
- Kobilka Institute of Innovative Drug Discovery, School of Medicine, The Chinese University of Hong Kong, Shenzhen, Shenzhen, China
| | - Selma Dahmane
- Wallenberg Centre for Molecular Medicine, Umeå University, Umeå, Sweden
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
- Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Rujuan Ti
- Warshel Institute for Computational Biology, The Chinese University of Hong Kong, Shenzhen, Shenzhen, China
- School of Medicine, The Chinese University of Hong Kong, Shenzhen, Shenzhen, China
| | - Xinyi Mai
- Kobilka Institute of Innovative Drug Discovery, School of Medicine, The Chinese University of Hong Kong, Shenzhen, Shenzhen, China
| | - Lizhe Zhu
- Warshel Institute for Computational Biology, The Chinese University of Hong Kong, Shenzhen, Shenzhen, China.
- School of Medicine, The Chinese University of Hong Kong, Shenzhen, Shenzhen, China.
| | - Lars-Anders Carlson
- Wallenberg Centre for Molecular Medicine, Umeå University, Umeå, Sweden.
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.
- Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden.
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden.
| | - Goran Stjepanovic
- Kobilka Institute of Innovative Drug Discovery, School of Medicine, The Chinese University of Hong Kong, Shenzhen, Shenzhen, China.
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8
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Barnaba C, Broadbent DG, Kaminsky EG, Perez GI, Schmidt JC. AMPK regulates phagophore-to-autophagosome maturation. J Cell Biol 2024; 223:e202309145. [PMID: 38775785 PMCID: PMC11110907 DOI: 10.1083/jcb.202309145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 03/28/2024] [Accepted: 05/04/2024] [Indexed: 05/24/2024] Open
Abstract
Autophagy is an important metabolic pathway that can non-selectively recycle cellular material or lead to targeted degradation of protein aggregates or damaged organelles. Autophagosome formation starts with autophagy factors accumulating on lipid vesicles containing ATG9. These phagophores attach to donor membranes, expand via ATG2-mediated lipid transfer, capture cargo, and mature into autophagosomes, ultimately fusing with lysosomes for their degradation. Autophagy can be activated by nutrient stress, for example, by a reduction in the cellular levels of amino acids. In contrast, how autophagy is regulated by low cellular ATP levels via the AMP-activated protein kinase (AMPK), an important therapeutic target, is less clear. Using live-cell imaging and an automated image analysis pipeline, we systematically dissect how nutrient starvation regulates autophagosome biogenesis. We demonstrate that glucose starvation downregulates autophagosome maturation by AMPK-mediated inhibition of phagophore tethering to donor membrane. Our results clarify AMPKs regulatory role in autophagy and highlight its potential as a therapeutic target to reduce autophagy.
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Affiliation(s)
- Carlo Barnaba
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, USA
| | - David G. Broadbent
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, USA
- College of Osteopathic Medicine, Michigan State University, East Lansing, MI, USA
- Department of Physiology, Michigan State University, East Lansing, MI, USA
| | - Emily G. Kaminsky
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, USA
| | - Gloria I. Perez
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, USA
| | - Jens C. Schmidt
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, USA
- Department of Obstetrics, Gynecology and Reproductive Biology, Michigan State University, East Lansing, MI, USA
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9
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Choi J, Jang H, Xuan Z, Park D. Emerging roles of ATG9/ATG9A in autophagy: implications for cell and neurobiology. Autophagy 2024:1-15. [PMID: 39099167 DOI: 10.1080/15548627.2024.2384349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Revised: 07/01/2024] [Accepted: 07/22/2024] [Indexed: 08/06/2024] Open
Abstract
Atg9, the only transmembrane protein among many autophagy-related proteins, was first identified in the year 2000 in yeast. Two homologs of Atg9, ATG9A and ATG9B, have been found in mammals. While ATG9B shows a tissue-specific expression pattern, such as in the placenta and pituitary gland, ATG9A is ubiquitously expressed. Additionally, ATG9A deficiency leads to severe defects not only at the molecular and cellular levels but also at the organismal level, suggesting key and fundamental roles for ATG9A. The subcellular localization of ATG9A on small vesicles and its functional relevance to autophagy have suggested a potential role for ATG9A in the lipid supply during autophagosome biogenesis. Nevertheless, the precise role of ATG9A in the autophagic process has remained a long-standing mystery, especially in neurons. Recent findings, however, including structural, proteomic, and biochemical analyses, have provided new insights into its function in the expansion of the phagophore membrane. In this review, we aim to understand various aspects of ATG9 (in invertebrates and plants)/ATG9A (in mammals), including its localization, trafficking, and other functions, in nonneuronal cells and neurons by comparing recent discoveries related to ATG9/ATG9A and proposing directions for future research.Abbreviation: AP-4: adaptor protein complex 4; ATG: autophagy related; cKO: conditional knockout; CLA-1: CLArinet (functional homolog of cytomatrix at the active zone proteins piccolo and fife); cryo-EM: cryogenic electron microscopy; ER: endoplasmic reticulum; KO: knockout; PAS: phagophore assembly site; PtdIns3K: class III phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol-3-phosphate; RB1CC1/FIP200: RB1 inducible coiled-coil 1; SV: synaptic vesicle; TGN: trans-Golgi network; ULK: unc-51 like autophagy activating kinase; WIPI2: WD repeat domain, phosphoinositide interacting 2.
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Affiliation(s)
- Jiyoung Choi
- Department of Medical and Biological Sciences, The Catholic University of Korea, Bucheon, South Korea
- Department of Biotechnology, The Catholic University of Korea, Bucheon, South Korea
| | - Haeun Jang
- Department of Medical and Biological Sciences, The Catholic University of Korea, Bucheon, South Korea
| | - Zhao Xuan
- School of Biology and Ecology, University of Maine, Orono, ME, USA
| | - Daehun Park
- Department of Medical and Biological Sciences, The Catholic University of Korea, Bucheon, South Korea
- Department of Biotechnology, The Catholic University of Korea, Bucheon, South Korea
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10
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Holzer E, Martens S, Tulli S. The Role of ATG9 Vesicles in Autophagosome Biogenesis. J Mol Biol 2024; 436:168489. [PMID: 38342428 DOI: 10.1016/j.jmb.2024.168489] [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: 12/19/2023] [Revised: 02/02/2024] [Accepted: 02/07/2024] [Indexed: 02/13/2024]
Abstract
Autophagy mediates the degradation and recycling of cellular material in the lysosomal system. Dysfunctional autophagy is associated with a plethora of diseases including uncontrolled infections, cancer and neurodegeneration. In macroautophagy (hereafter autophagy) this material is encapsulated in double membrane vesicles, the autophagosomes, which form upon induction of autophagy. The precursors to autophagosomes, referred to as phagophores, first appear as small flattened membrane cisternae, which gradually enclose the cargo material as they grow. The assembly of phagophores during autophagy initiation has been a major subject of investigation over the past decades. A special focus has been ATG9, the only conserved transmembrane protein among the core machinery. The majority of ATG9 localizes to small Golgi-derived vesicles. Here we review the recent advances and breakthroughs regarding our understanding of how ATG9 and the vesicles it resides in serve to assemble the autophagy machinery and to establish membrane contact sites for autophagosome biogenesis. We also highlight open questions in the field that need to be addressed in the years to come.
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Affiliation(s)
- Elisabeth Holzer
- Max Perutz Labs, Vienna BioCenter Campus (VBC), Vienna, Austria; University of Vienna, Max Perutz Labs, Department of Biochemistry and Cell Biology, Vienna, Austria; Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, Campus-Vienna-Biocenter 1, Vienna, Austria.
| | - Sascha Martens
- Max Perutz Labs, Vienna BioCenter Campus (VBC), Vienna, Austria; University of Vienna, Max Perutz Labs, Department of Biochemistry and Cell Biology, Vienna, Austria.
| | - Susanna Tulli
- Max Perutz Labs, Vienna BioCenter Campus (VBC), Vienna, Austria; University of Vienna, Max Perutz Labs, Department of Biochemistry and Cell Biology, Vienna, Austria.
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11
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Isola D, Elazar Z. Phospholipid Supply for Autophagosome Biogenesis. J Mol Biol 2024; 436:168691. [PMID: 38944336 DOI: 10.1016/j.jmb.2024.168691] [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: 04/09/2024] [Revised: 06/10/2024] [Accepted: 06/24/2024] [Indexed: 07/01/2024]
Abstract
Autophagy is a cellular degradation pathway where double-membrane autophagosomes form de novo to engulf cytoplasmic material destined for lysosomal degradation. This process requires regulated membrane remodeling, beginning with the initial autophagosomal precursor and progressing to its elongation and maturation into a fully enclosed, fusion-capable vesicle. While the core protein machinery involved in autophagosome formation has been extensively studied over the past two decades, the role of phospholipids in this process has only recently been studied. This review focuses on the phospholipid composition of the phagophore membrane and the mechanisms that supply lipids to expand this unique organelle.
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Affiliation(s)
- Damilola Isola
- Departments of Biomolecular Sciences, The Weizmann Institute of Science, 76100 Rehovot, Israel
| | - Zvulun Elazar
- Departments of Biomolecular Sciences, The Weizmann Institute of Science, 76100 Rehovot, Israel.
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12
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Paddar MA, Wang F, Trosdal ES, Hendrix E, He Y, Salemi M, Mudd M, Jia J, Duque TLA, Javed R, Phinney B, Deretic V. Noncanonical roles of ATG5 and membrane atg8ylation in retromer assembly and function. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.10.602886. [PMID: 39026874 PMCID: PMC11257513 DOI: 10.1101/2024.07.10.602886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
ATG5 is one of the core autophagy proteins with additional functions such as noncanonical membrane atg8ylation, which among a growing number of biological outputs includes control of tuberculosis in animal models. Here we show that ATG5 associates with retromer's core components VPS26, VPS29 and VPS35 and modulates retromer function. Knockout of ATG5 blocked trafficking of a key glucose transporter sorted by the retromer, GLUT1, to the plasma membrane. Knockouts of other genes essential for membrane atg8ylation, of which ATG5 is a component, affected GLUT1 sorting, indicating that membrane atg8ylation as a process affects retromer function and endosomal sorting. The contribution of membrane atg8ylation to retromer function in GLUT1 sorting was independent of canonical autophagy. These findings expand the scope of membrane atg8ylation to specific sorting processes in the cell dependent on the retromer and its known interactors.
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Affiliation(s)
- Masroor Ahmad Paddar
- Autophagy, Inflammation and Metabolism Center of Biochemical Research Excellence
- Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, 915 Camino de Salud, NE, Albuquerque, NM 87131, USA
| | - Fulong Wang
- Autophagy, Inflammation and Metabolism Center of Biochemical Research Excellence
- Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, 915 Camino de Salud, NE, Albuquerque, NM 87131, USA
| | - Einar S Trosdal
- Autophagy, Inflammation and Metabolism Center of Biochemical Research Excellence
- Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, 915 Camino de Salud, NE, Albuquerque, NM 87131, USA
| | - Emily Hendrix
- Department of Chemistry & Chemical Biology, The University of New Mexico, Albuquerque, NM, USA
| | - Yi He
- Department of Chemistry & Chemical Biology, The University of New Mexico, Albuquerque, NM, USA
| | - Michelle Salemi
- Proteomics Core Facility, UC Davis Genome Center, University of California, Davis, CA 95616, USA
| | - Michal Mudd
- Autophagy, Inflammation and Metabolism Center of Biochemical Research Excellence
- Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, 915 Camino de Salud, NE, Albuquerque, NM 87131, USA
| | - Jingyue Jia
- Autophagy, Inflammation and Metabolism Center of Biochemical Research Excellence
- Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, 915 Camino de Salud, NE, Albuquerque, NM 87131, USA
| | - Thabata L A Duque
- Autophagy, Inflammation and Metabolism Center of Biochemical Research Excellence
- Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, 915 Camino de Salud, NE, Albuquerque, NM 87131, USA
| | - Ruheena Javed
- Autophagy, Inflammation and Metabolism Center of Biochemical Research Excellence
- Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, 915 Camino de Salud, NE, Albuquerque, NM 87131, USA
| | - Brett Phinney
- Proteomics Core Facility, UC Davis Genome Center, University of California, Davis, CA 95616, USA
| | - Vojo Deretic
- Autophagy, Inflammation and Metabolism Center of Biochemical Research Excellence
- Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, 915 Camino de Salud, NE, Albuquerque, NM 87131, USA
- Lead Contact
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13
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Nähse V, Stenmark H, Schink KO. Omegasomes control formation, expansion, and closure of autophagosomes. Bioessays 2024; 46:e2400038. [PMID: 38724256 DOI: 10.1002/bies.202400038] [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: 02/15/2024] [Revised: 04/04/2024] [Accepted: 04/05/2024] [Indexed: 05/28/2024]
Abstract
Autophagy, an essential cellular process for maintaining cellular homeostasis and eliminating harmful cytoplasmic objects, involves the de novo formation of double-membraned autophagosomes that engulf and degrade cellular debris, protein aggregates, damaged organelles, and pathogens. Central to this process is the phagophore, which forms from donor membranes rich in lipids synthesized at various cellular sites, including the endoplasmic reticulum (ER), which has emerged as a primary source. The ER-associated omegasomes, characterized by their distinctive omega-shaped structure and accumulation of phosphatidylinositol 3-phosphate (PI3P), play a pivotal role in autophagosome formation. Omegasomes are thought to serve as platforms for phagophore assembly by recruiting essential proteins such as DFCP1/ZFYVE1 and facilitating lipid transfer to expand the phagophore. Despite the critical importance of phagophore biogenesis, many aspects remain poorly understood, particularly the complete range of proteins involved in omegasome dynamics, and the detailed mechanisms of lipid transfer and membrane contact site formation.
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Affiliation(s)
- Viola Nähse
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Harald Stenmark
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Kay O Schink
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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14
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Yi S, Wang L, Ho MS, Zhang S. The autophagy protein Atg9 functions in glia and contributes to parkinsonian symptoms in a Drosophila model of Parkinson's disease. Neural Regen Res 2024; 19:1150-1155. [PMID: 37862221 PMCID: PMC10749615 DOI: 10.4103/1673-5374.382259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 05/31/2023] [Accepted: 07/10/2023] [Indexed: 10/22/2023] Open
Abstract
Parkinson's disease is a progressive neurodegenerative disease characterized by motor deficits, dopaminergic neuron loss, and brain accumulation of α-synuclein aggregates called Lewy bodies. Dysfunction in protein degradation pathways, such as autophagy, has been demonstrated in neurons as a critical mechanism for eliminating protein aggregates in Parkinson's disease. However, it is less well understood how protein aggregates are eliminated in glia, the other cell type in the brain. In the present study, we show that autophagy-related gene 9 (Atg9), the only transmembrane protein in the autophagy machinery, is highly expressed in Drosophila glia from adult brain. Results from immunostaining and live cell imaging analysis reveal that a portion of Atg9 localizes to the trans-Golgi network, autophagosomes, and lysosomes in glia. Atg9 is persistently in contact with these organelles. Lacking glial atg9 reduces the number of omegasomes and autophagosomes, and impairs autophagic substrate degradation. This suggests that glial Atg9 participates in the early steps of autophagy, and hence the control of autophagic degradation. Importantly, loss of glial atg9 induces parkinsonian symptoms in Drosophila including progressive loss of dopaminergic neurons, locomotion deficits, and glial activation. Our findings identify a functional role of Atg9 in glial autophagy and establish a potential link between glial autophagy and Parkinson's disease. These results may provide new insights on the underlying mechanism of Parkinson's disease.
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Affiliation(s)
- Shuanglong Yi
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Linfang Wang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Margaret S. Ho
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Shiping Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
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15
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Ortega MA, Fraile-Martinez O, de Leon-Oliva D, Boaru DL, Lopez-Gonzalez L, García-Montero C, Alvarez-Mon MA, Guijarro LG, Torres-Carranza D, Saez MA, Diaz-Pedrero R, Albillos A, Alvarez-Mon M. Autophagy in Its (Proper) Context: Molecular Basis, Biological Relevance, Pharmacological Modulation, and Lifestyle Medicine. Int J Biol Sci 2024; 20:2532-2554. [PMID: 38725847 PMCID: PMC11077378 DOI: 10.7150/ijbs.95122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Accepted: 04/04/2024] [Indexed: 05/12/2024] Open
Abstract
Autophagy plays a critical role in maintaining cellular homeostasis and responding to various stress conditions by the degradation of intracellular components. In this narrative review, we provide a comprehensive overview of autophagy's cellular and molecular basis, biological significance, pharmacological modulation, and its relevance in lifestyle medicine. We delve into the intricate molecular mechanisms that govern autophagy, including macroautophagy, microautophagy and chaperone-mediated autophagy. Moreover, we highlight the biological significance of autophagy in aging, immunity, metabolism, apoptosis, tissue differentiation and systemic diseases, such as neurodegenerative or cardiovascular diseases and cancer. We also discuss the latest advancements in pharmacological modulation of autophagy and their potential implications in clinical settings. Finally, we explore the intimate connection between lifestyle factors and autophagy, emphasizing how nutrition, exercise, sleep patterns and environmental factors can significantly impact the autophagic process. The integration of lifestyle medicine into autophagy research opens new avenues for promoting health and longevity through personalized interventions.
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Affiliation(s)
- Miguel A Ortega
- Department of Medicine and Medical Specialities, Faculty of Medicine and Health Sciences, University of Alcalá, 28801 Alcala de Henares, Spain
- Ramón y Cajal Institute of Sanitary Research (IRYCIS), 28034 Madrid, Spain
| | - Oscar Fraile-Martinez
- Department of Medicine and Medical Specialities, Faculty of Medicine and Health Sciences, University of Alcalá, 28801 Alcala de Henares, Spain
- Ramón y Cajal Institute of Sanitary Research (IRYCIS), 28034 Madrid, Spain
| | - Diego de Leon-Oliva
- Department of Medicine and Medical Specialities, Faculty of Medicine and Health Sciences, University of Alcalá, 28801 Alcala de Henares, Spain
- Ramón y Cajal Institute of Sanitary Research (IRYCIS), 28034 Madrid, Spain
| | - Diego Liviu Boaru
- Department of Medicine and Medical Specialities, Faculty of Medicine and Health Sciences, University of Alcalá, 28801 Alcala de Henares, Spain
- Ramón y Cajal Institute of Sanitary Research (IRYCIS), 28034 Madrid, Spain
| | - Laura Lopez-Gonzalez
- Ramón y Cajal Institute of Sanitary Research (IRYCIS), 28034 Madrid, Spain
- Department of Surgery, Medical and Social Sciences, Faculty of Medicine and Health Sciences, University of Alcalá, 28801 Alcala de Henares, Spain
| | - Cielo García-Montero
- Department of Medicine and Medical Specialities, Faculty of Medicine and Health Sciences, University of Alcalá, 28801 Alcala de Henares, Spain
- Ramón y Cajal Institute of Sanitary Research (IRYCIS), 28034 Madrid, Spain
| | - Miguel Angel Alvarez-Mon
- Department of Medicine and Medical Specialities, Faculty of Medicine and Health Sciences, University of Alcalá, 28801 Alcala de Henares, Spain
- Ramón y Cajal Institute of Sanitary Research (IRYCIS), 28034 Madrid, Spain
| | - Luis G Guijarro
- Ramón y Cajal Institute of Sanitary Research (IRYCIS), 28034 Madrid, Spain
- Unit of Biochemistry and Molecular Biology, Department of System Biology (CIBEREHD), University of Alcalá, 28801 Alcala de Henares, Spain
| | - Diego Torres-Carranza
- Department of Medicine and Medical Specialities, Faculty of Medicine and Health Sciences, University of Alcalá, 28801 Alcala de Henares, Spain
- Ramón y Cajal Institute of Sanitary Research (IRYCIS), 28034 Madrid, Spain
| | - Miguel A Saez
- Department of Medicine and Medical Specialities, Faculty of Medicine and Health Sciences, University of Alcalá, 28801 Alcala de Henares, Spain
- Ramón y Cajal Institute of Sanitary Research (IRYCIS), 28034 Madrid, Spain
- Pathological Anatomy Service, Central University Hospital of Defence-UAH Madrid, 28801 Alcala de Henares, Spain
| | - Raul Diaz-Pedrero
- Ramón y Cajal Institute of Sanitary Research (IRYCIS), 28034 Madrid, Spain
- Department of Surgery, Medical and Social Sciences, Faculty of Medicine and Health Sciences, University of Alcalá, 28801 Alcala de Henares, Spain
- Department of General and Digestive Surgery, Príncipe de Asturias Universitary Hospital, 28805 Alcala de Henares, Spain
| | - Agustin Albillos
- Department of Medicine and Medical Specialities, Faculty of Medicine and Health Sciences, University of Alcalá, 28801 Alcala de Henares, Spain
- Ramón y Cajal Institute of Sanitary Research (IRYCIS), 28034 Madrid, Spain
| | - Melchor Alvarez-Mon
- Department of Medicine and Medical Specialities, Faculty of Medicine and Health Sciences, University of Alcalá, 28801 Alcala de Henares, Spain
- Ramón y Cajal Institute of Sanitary Research (IRYCIS), 28034 Madrid, Spain
- Immune System Diseases-Rheumatology, Oncology Service an Internal Medicine (CIBEREHD), Príncipe de Asturias University Hospital, 28806 Alcala de Henares, Spain
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16
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Schmid M, Fischer P, Engl M, Widder J, Kerschbaum-Gruber S, Slade D. The interplay between autophagy and cGAS-STING signaling and its implications for cancer. Front Immunol 2024; 15:1356369. [PMID: 38660307 PMCID: PMC11039819 DOI: 10.3389/fimmu.2024.1356369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 03/26/2024] [Indexed: 04/26/2024] Open
Abstract
Autophagy is an intracellular process that targets various cargos for degradation, including members of the cGAS-STING signaling cascade. cGAS-STING senses cytosolic double-stranded DNA and triggers an innate immune response through type I interferons. Emerging evidence suggests that autophagy plays a crucial role in regulating and fine-tuning cGAS-STING signaling. Reciprocally, cGAS-STING pathway members can actively induce canonical as well as various non-canonical forms of autophagy, establishing a regulatory network of feedback mechanisms that alter both the cGAS-STING and the autophagic pathway. The crosstalk between autophagy and the cGAS-STING pathway impacts a wide variety of cellular processes such as protection against pathogenic infections as well as signaling in neurodegenerative disease, autoinflammatory disease and cancer. Here we provide a comprehensive overview of the mechanisms involved in autophagy and cGAS-STING signaling, with a specific focus on the interactions between the two pathways and their importance for cancer.
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Affiliation(s)
- Maximilian Schmid
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
- Comprehensive Cancer Center, Medical University of Vienna, Vienna, Austria
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
- Department of Medical Biochemistry, Medical University of Vienna, Max Perutz Labs, Vienna Biocenter, Vienna, Austria
| | - Patrick Fischer
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
- Comprehensive Cancer Center, Medical University of Vienna, Vienna, Austria
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
- Department of Medical Biochemistry, Medical University of Vienna, Max Perutz Labs, Vienna Biocenter, Vienna, Austria
| | - Magdalena Engl
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
- Comprehensive Cancer Center, Medical University of Vienna, Vienna, Austria
- Department of Medical Biochemistry, Medical University of Vienna, Max Perutz Labs, Vienna Biocenter, Vienna, Austria
- Vienna Biocenter PhD Program, a Doctoral School of the University of Vienna and Medical University of Vienna, Vienna, Austria
| | - Joachim Widder
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
- Comprehensive Cancer Center, Medical University of Vienna, Vienna, Austria
| | - Sylvia Kerschbaum-Gruber
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
- Comprehensive Cancer Center, Medical University of Vienna, Vienna, Austria
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
| | - Dea Slade
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
- Comprehensive Cancer Center, Medical University of Vienna, Vienna, Austria
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria
- Department of Medical Biochemistry, Medical University of Vienna, Max Perutz Labs, Vienna Biocenter, Vienna, Austria
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17
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Binotti B, Ninov M, Cepeda AP, Ganzella M, Matti U, Riedel D, Urlaub H, Sambandan S, Jahn R. ATG9 resides on a unique population of small vesicles in presynaptic nerve terminals. Autophagy 2024; 20:883-901. [PMID: 37881948 PMCID: PMC11062364 DOI: 10.1080/15548627.2023.2274204] [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: 02/01/2023] [Accepted: 10/17/2023] [Indexed: 10/27/2023] Open
Abstract
In neurons, autophagosome biogenesis occurs mainly in distal axons, followed by maturation during retrograde transport. Autophagosomal growth depends on the supply of membrane lipids which requires small vesicles containing ATG9, a lipid scramblase essential for macroautophagy/autophagy. Here, we show that ATG9-containing vesicles are enriched in synapses and resemble synaptic vesicles in size and density. The proteome of ATG9-containing vesicles immuno-isolated from nerve terminals showed conspicuously low levels of trafficking proteins except of the AP2-complex and some enzymes involved in endosomal phosphatidylinositol metabolism. Super resolution microscopy of nerve terminals and isolated vesicles revealed that ATG9-containing vesicles represent a distinct vesicle population with limited overlap not only with synaptic vesicles but also other membranes of the secretory pathway, uncovering a surprising heterogeneity in their membrane composition. Our results are compatible with the view that ATG9-containing vesicles function as lipid shuttles that scavenge membrane lipids from various intracellular membranes to support autophagosome biogenesis.Abbreviations: AP: adaptor related protein complex: ATG2: autophagy related 2; ATG9: autophagy related 9; DNA PAINT: DNA-based point accumulation for imaging in nanoscale topography; DyMIN STED: dynamic minimum stimulated emission depletion; EL: endosome and lysosome; ER: endoplasmic reticulum; GA: Golgi apparatus; iBAQ: intensity based absolute quantification; LAMP: lysosomal-associated membrane protein; M6PR: mannose-6-phosphate receptor, cation dependent; Minflux: minimal photon fluxes; Mito: mitochondria; MS: mass spectrometry; PAS: phagophore assembly site; PM: plasma membrane; Px: peroxisome; RAB26: RAB26, member RAS oncogene family; RAB3A: RAB3A, member RAS oncogene family; RAB5A: RAB5A, member RAS oncogene family; SNARE: soluble N-ethylmaleimide-sensitive-factor attachment receptor; SVs: synaptic vesicles; SYP: synaptophysin; TGN: trans-Golgi network; TRAPP: transport protein particle; VTI1: vesicle transport through interaction with t-SNAREs.
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Affiliation(s)
- Beyenech Binotti
- Laboratory of Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Department of Biochemistry, Biocenter, University of Würzburg, Würzburg, Germany
| | - Momchil Ninov
- Laboratory of Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Bioanalytics, Institute of Clinical Chemistry, University Medical Center Göttingen, Germany
- Bioanalytical Mass Spectrometry, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Andreia P. Cepeda
- Bioanalytical Mass Spectrometry, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Marcelo Ganzella
- Laboratory of Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Ulf Matti
- Abberior Instruments GmbH, Göttingen, Germany
| | - Dietmar Riedel
- Facility for Transmission Electron Microscopy, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Henning Urlaub
- Bioanalytics, Institute of Clinical Chemistry, University Medical Center Göttingen, Germany
- Bioanalytical Mass Spectrometry, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Cluster of Excellence “Multiscale Bioimaging : from Molecular Machines to Networks of Excitable Cells” (MBExC), University of Göttingen, Göttingen, Germany
| | - Sivakumar Sambandan
- Laboratory of Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Synaptic Metal Ion Dynamics and Signalin, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Reinhard Jahn
- Laboratory of Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
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18
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Wallace NS, Gadbery JE, Cohen CI, Kendall AK, Jackson LP. Tepsin binds LC3B to promote ATG9A trafficking and delivery. Mol Biol Cell 2024; 35:ar56. [PMID: 38381558 PMCID: PMC11064669 DOI: 10.1091/mbc.e23-09-0359-t] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 02/07/2024] [Accepted: 02/16/2024] [Indexed: 02/23/2024] Open
Abstract
Tepsin is an established accessory protein found in Adaptor Protein 4 (AP-4) coated vesicles, but the biological role of tepsin remains unknown. AP-4 vesicles originate at the trans-Golgi network (TGN) and target the delivery of ATG9A, a scramblase required for autophagosome biogenesis, to the cell periphery. Using in silico methods, we identified a putative LC3-Interacting Region (LIR) motif in tepsin. Biochemical experiments using purified recombinant proteins indicate tepsin directly binds LC3B preferentially over other members of the mammalian ATG8 family. Calorimetry and structural modeling data indicate this interaction occurs with micromolar affinity using the established LC3B LIR docking site. Loss of tepsin in cultured cells dysregulates ATG9A export from the TGN as well as ATG9A distribution at the cell periphery. Tepsin depletion in a mRFP-GFP-LC3B HeLa reporter cell line using siRNA knockdown increases autophagosome volume and number, but does not appear to affect flux through the autophagic pathway. Reintroduction of wild-type tepsin partially rescues ATG9A cargo trafficking defects. In contrast, reintroducing tepsin with a mutated LIR motif or missing N-terminus drives diffuse ATG9A subcellular distribution. Together, these data suggest roles for tepsin in cargo export from the TGN; ensuring delivery of ATG9A-positive vesicles; and in overall maintenance of autophagosome structure.
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Affiliation(s)
- Natalie S. Wallace
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37232
| | - John E. Gadbery
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37232
| | - Cameron I. Cohen
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37232
| | - Amy K. Kendall
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37232
| | - Lauren P. Jackson
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37232
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37232
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19
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Varela YR, Iriondo MN, Goñi FM, Alonso A, Montes LR. Ceramide regulation of autophagy: A biophysical approach. Biochim Biophys Acta Mol Cell Biol Lipids 2024; 1869:159444. [PMID: 38056762 DOI: 10.1016/j.bbalip.2023.159444] [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: 11/06/2023] [Revised: 11/29/2023] [Accepted: 11/30/2023] [Indexed: 12/08/2023]
Abstract
Specific membrane lipids play unique roles in (macro)autophagy. Those include phosphatidylethanolamine, to which LC3/GABARAP autophagy proteins become covalently bound in the process, or cardiolipin, an important effector in mitochondrial autophagy (or mitophagy). Ceramide (Cer), or N-acyl sphingosine, is one of the simplest sphingolipids, known as a stress signal in the apoptotic pathway. Moreover, Cer is increasingly being recognized as an autophagy activator, although its mechanism of action is unclear. In the present review, the proposed Cer roles in autophagy are summarized, together with some biophysical properties of Cer in membranes. Possible pathways for Cer activation of autophagy are discussed, including specific protein binding of the lipid, and Cer-dependent perturbation of bilayer properties. Cer generation of lateral inhomogeneities (domain formation) is given special attention. Recent biophysical results, including fluorescence and atomic force microscopy data, show Cer-promoted enhanced binding of LC3/GABARAP to lipid bilayers. These observations could be interpreted in terms of the putative formation of Cer-rich nanodomains.
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Affiliation(s)
- Yaiza R Varela
- Instituto Biofisika (UPV/EHU, CSIC) and Departamento de Bioquímica, Universidad del País Vasco, 48940 Leioa, Spain
| | - Marina N Iriondo
- Instituto Biofisika (UPV/EHU, CSIC) and Departamento de Bioquímica, Universidad del País Vasco, 48940 Leioa, Spain
| | - Félix M Goñi
- Instituto Biofisika (UPV/EHU, CSIC) and Departamento de Bioquímica, Universidad del País Vasco, 48940 Leioa, Spain
| | - Alicia Alonso
- Instituto Biofisika (UPV/EHU, CSIC) and Departamento de Bioquímica, Universidad del País Vasco, 48940 Leioa, Spain.
| | - L Ruth Montes
- Instituto Biofisika (UPV/EHU, CSIC) and Departamento de Bioquímica, Universidad del País Vasco, 48940 Leioa, Spain
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20
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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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21
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Maruyama T, Hama Y, Noda NN. Mechanisms of mitochondrial reorganization. J Biochem 2024; 175:167-178. [PMID: 38016932 DOI: 10.1093/jb/mvad098] [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: 08/30/2023] [Revised: 10/27/2023] [Accepted: 11/09/2023] [Indexed: 11/30/2023] Open
Abstract
The cytoplasm of eukaryotes is dynamically zoned by membrane-bound and membraneless organelles. Cytoplasmic zoning allows various biochemical reactions to take place at the right time and place. Mitochondrion is a membrane-bound organelle that provides a zone for intracellular energy production and metabolism of lipids and iron. A key feature of mitochondria is their high dynamics: mitochondria constantly undergo fusion and fission, and excess or damaged mitochondria are selectively eliminated by mitophagy. Therefore, mitochondria are appropriate model systems to understand dynamic cytoplasmic zoning by membrane organelles. In this review, we summarize the molecular mechanisms of mitochondrial fusion and fission as well as mitophagy unveiled through studies using yeast and mammalian models.
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Affiliation(s)
- Tatsuro Maruyama
- Institute of Microbial Chemistry (BIKAKEN), 3-14-23 Kamiosaki, Shinagawa-ku, Tokyo 141-0021, Japan
| | - Yutaro Hama
- Institute of Microbial Chemistry (BIKAKEN), 3-14-23 Kamiosaki, Shinagawa-ku, Tokyo 141-0021, Japan
- Institute for Genetic Medicine, Hokkaido University, Kita 15, Nishi 7, Kita-ku, Sapporo 060-0815, Japan
| | - Nobuo N Noda
- Institute of Microbial Chemistry (BIKAKEN), 3-14-23 Kamiosaki, Shinagawa-ku, Tokyo 141-0021, Japan
- Institute for Genetic Medicine, Hokkaido University, Kita 15, Nishi 7, Kita-ku, Sapporo 060-0815, Japan
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22
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van Vliet AR, Jefferies HBJ, Faull PA, Chadwick J, Ibrahim F, Skehel MJ, Tooze SA. Exploring the ATG9A interactome uncovers interaction with VPS13A. J Cell Sci 2024; 137:jcs261081. [PMID: 38294121 PMCID: PMC10911177 DOI: 10.1242/jcs.261081] [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: 02/16/2023] [Accepted: 01/17/2024] [Indexed: 02/01/2024] Open
Abstract
ATG9A, a transmembrane protein of the core autophagy pathway, cycles between the Golgi, endosomes and a vesicular compartment. ATG9A was recently shown to act as a lipid scramblase, and this function is thought to require its interaction with another core autophagy protein, ATG2A, which acts as a lipid transfer protein. Together, ATG9A and ATG2A are proposed to function to expand the growing autophagosome. However, ATG9A is implicated in other pathways including membrane repair and lipid droplet homeostasis. To elucidate other ATG9A interactors within the autophagy pathway, or interactors beyond autophagy, we performed an interactome analysis through mass spectrometry. This analysis revealed a host of proteins involved in lipid synthesis and trafficking, including ACSL3, VPS13A and VPS13C. Furthermore, we show that ATG9A directly interacts with VPS13A and forms a complex that is distinct from the ATG9A-ATG2A complex.
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Affiliation(s)
| | | | - Peter A. Faull
- Proteomics Science Technology Platform, The Francis Crick Institute, London NW1 1AT, UK
| | | | - Fairouz Ibrahim
- Proteomics Science Technology Platform, The Francis Crick Institute, London NW1 1AT, UK
| | - Mark J. Skehel
- Proteomics Science Technology Platform, The Francis Crick Institute, London NW1 1AT, UK
| | - Sharon A. Tooze
- Molecular Cell Biology of Autophagy, The Francis Crick Institute, London NW1 1AT, UK
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23
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Proikas-Cezanne T, Haas ML, Pastor-Maldonado CJ, Schüssele DS. Human WIPI β-propeller function in autophagy and neurodegeneration. FEBS Lett 2024; 598:127-139. [PMID: 38058212 DOI: 10.1002/1873-3468.14782] [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: 09/21/2023] [Revised: 11/10/2023] [Accepted: 11/10/2023] [Indexed: 12/08/2023]
Abstract
The four human WIPI β-propellers, WIPI1 through WIPI4, belong to the ancient PROPPIN family and fulfill scaffold functions in the control of autophagy. In this context, WIPI β-propellers function as PI3P effectors during autophagosome formation and loss of WIPI function negatively impacts autophagy and contributes to neurodegeneration. Of particular interest are mutations in WDR45, the human gene that encodes WIPI4. Sporadic WDR45 mutations are the cause of a rare human neurodegenerative disease called BPAN, hallmarked by high brain iron accumulation. Here, we discuss the current understanding of the functions of human WIPI β-propellers and address unanswered questions with a particular focus on the role of WIPI4 in autophagy and BPAN.
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Affiliation(s)
- Tassula Proikas-Cezanne
- Interfaculty Institute of Cell Biology, Department of Biology, Faculty of Science, Eberhard Karls University Tübingen, Germany
| | - Maximilian L Haas
- Interfaculty Institute of Cell Biology, Department of Biology, Faculty of Science, Eberhard Karls University Tübingen, Germany
| | - Carmen J Pastor-Maldonado
- Interfaculty Institute of Cell Biology, Department of Biology, Faculty of Science, Eberhard Karls University Tübingen, Germany
| | - David S Schüssele
- Interfaculty Institute of Cell Biology, Department of Biology, Faculty of Science, Eberhard Karls University Tübingen, Germany
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24
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Tooze SA, Zhang W, Lazzeri G, Gahlot D, Thukral L, Covino R, Nishimura T. Membrane association of the ATG8 conjugation machinery emerges as a key regulatory feature for autophagosome biogenesis. FEBS Lett 2024; 598:107-113. [PMID: 37259601 PMCID: PMC10952647 DOI: 10.1002/1873-3468.14676] [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: 04/22/2023] [Revised: 05/10/2023] [Accepted: 05/10/2023] [Indexed: 06/02/2023]
Abstract
Autophagy is a highly conserved intracellular pathway that is essential for survival in all eukaryotes. In healthy cells, autophagy is used to remove damaged intracellular components, which can be as simple as unfolded proteins or as complex as whole mitochondria. Once the damaged component is captured, the autophagosome engulfs it and closes, isolating the content from the cytoplasm. The autophagosome then fuses with the late endosome and/or lysosome to deliver its content to the lysosome for degradation. Formation of the autophagosome, sequestration or capture of content, and closure all require the ATG proteins, which constitute the essential core autophagy protein machinery. This brief 'nutshell' will highlight recent data revealing the importance of small membrane-associated domains in the ATG proteins. In particular, recent findings from two parallel studies reveal the unexpected key role of α-helical structures in the ATG8 conjugation machinery and ATG8s. These studies illustrate how unique membrane association modules can control the formation of autophagosomes.
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Affiliation(s)
- Sharon A. Tooze
- Molecular Cell Biology of Autophagy LaboratoryThe Francis Crick InstituteLondonUK
| | - Wenxin Zhang
- Molecular Cell Biology of Autophagy LaboratoryThe Francis Crick InstituteLondonUK
| | | | - Deepanshi Gahlot
- CSIR‐Institute of Genomics and Integrative BiologyNew DelhiIndia
- Academy of Scientific and Innovative Research (AcSIR)GhaziabadIndia
| | - Lipi Thukral
- CSIR‐Institute of Genomics and Integrative BiologyNew DelhiIndia
- Academy of Scientific and Innovative Research (AcSIR)GhaziabadIndia
| | | | - Taki Nishimura
- PRESTO, Japan Science and Technology AgencyTokyoJapan
- Department of Biochemistry and Molecular Biology, Graduate School of MedicineThe University of TokyoJapan
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25
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Nguyen A, Faesen AC. The role of the HORMA domain proteins ATG13 and ATG101 in initiating autophagosome biogenesis. FEBS Lett 2024; 598:114-126. [PMID: 37567770 DOI: 10.1002/1873-3468.14717] [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: 06/30/2023] [Revised: 08/03/2023] [Accepted: 08/04/2023] [Indexed: 08/13/2023]
Abstract
Autophagy is a process of regulated degradation. It eliminates damaged and unnecessary cellular components by engulfing them with a de novo-generated organelle: the double-membrane autophagosome. The past three decades have provided us with a detailed parts list of the autophagy initiation machinery, have developed important insights into how these processes function and have identified regulatory proteins. It is now clear that autophagosome biogenesis requires the timely assembly of a complex machinery. However, it is unclear how a putative stable machine is assembled and disassembled and how the different parts cooperate to perform its overall function. Although they have long been somewhat enigmatic in their precise role, HORMA domain proteins (first identified in Hop1p, Rev7p and MAD2 proteins) autophagy-related protein 13 (ATG13) and ATG101 of the ULK-kinase complex have emerged as important coordinators of the autophagy-initiating subcomplexes. Here, we will particularly focus on ATG13 and ATG101 and the role of their unusual metamorphosis in initiating autophagosome biogenesis. We will also explore how this metamorphosis could potentially be purposefully rate-limiting and speculate on how it could regulate the spontaneous self-assembly of the autophagy-initiating machinery.
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Affiliation(s)
- Anh Nguyen
- Laboratory of Biochemistry of Signal Dynamics, Max-Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Alex C Faesen
- Laboratory of Biochemistry of Signal Dynamics, Max-Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
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26
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Liu Z, Yang Q, Wu P, Li Y, Lin Y, Liu W, Guo S, Liu Y, Huang Y, Xu P, Qian Y, Xie Q. Dynamic monitoring of TGW6 by selective autophagy during grain development in rice. THE NEW PHYTOLOGIST 2023; 240:2419-2435. [PMID: 37743547 DOI: 10.1111/nph.19271] [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: 08/09/2023] [Accepted: 08/31/2023] [Indexed: 09/26/2023]
Abstract
Crop yield must increase to achieve food security in the face of a growing population and environmental deterioration. Grain size is a prime breeding target for improving grain yield and quality in crop. Here, we report that autophagy emerges as an important regulatory pathway contributing to grain size and quality in rice. Mutations of rice Autophagy-related 9b (OsATG9b) or OsATG13a causes smaller grains and increase of chalkiness, whereas overexpression of either promotes grain size and quality. We also demonstrate that THOUSAND-GRAIN WEIGHT 6 (TGW6), a superior allele that regulates grain size and quality in the rice variety Kasalath, interacts with OsATG8 via the canonical Atg8-interacting motif (AIM), and then is recruited to the autophagosome for selective degradation. In consistent, alteration of either OsATG9b or OsATG13a expression results in reciprocal modulation of TGW6 abundance during grain growth. Genetic analyses confirmed that knockout of TGW6 in either osatg9b or osatg13a mutants can partially rescue their grain size defects, indicating that TGW6 is one of the substrates for autophagy to regulate grain development. We therefore propose a potential framework for autophagy in contributing to grain size and quality in crops.
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Affiliation(s)
- Zinan Liu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Key Laboratory for Enhancing Resource Use Efficiency of Crops in South China, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Plant Molecular Breeding, College of Agriculture, South China Agricultural University, Guangzhou, 510642, China
| | - Qianying Yang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Key Laboratory for Enhancing Resource Use Efficiency of Crops in South China, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Plant Molecular Breeding, College of Agriculture, South China Agricultural University, Guangzhou, 510642, China
| | - Pingfan Wu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Key Laboratory for Enhancing Resource Use Efficiency of Crops in South China, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Plant Molecular Breeding, College of Agriculture, South China Agricultural University, Guangzhou, 510642, China
| | - Yifan Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Key Laboratory for Enhancing Resource Use Efficiency of Crops in South China, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Plant Molecular Breeding, College of Agriculture, South China Agricultural University, Guangzhou, 510642, China
| | - Yanni Lin
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Key Laboratory for Enhancing Resource Use Efficiency of Crops in South China, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Plant Molecular Breeding, College of Agriculture, South China Agricultural University, Guangzhou, 510642, China
| | - Wanqing Liu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Key Laboratory for Enhancing Resource Use Efficiency of Crops in South China, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Plant Molecular Breeding, College of Agriculture, South China Agricultural University, Guangzhou, 510642, China
- Guangdong Academy of Agricultural Sciences, Rice Research Institute, Guangzhou, 510640, China
| | - Shaoying Guo
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Key Laboratory for Enhancing Resource Use Efficiency of Crops in South China, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Plant Molecular Breeding, College of Agriculture, South China Agricultural University, Guangzhou, 510642, China
| | - Yunfeng Liu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences and Technology, Guangxi University, Nanning, 530004, China
| | - Yifeng Huang
- Institute of Crop and Nuclear Technology Utilization, Zhejiang Academy of Agricultural Science, Hangzhou, 310001, China
| | - Peng Xu
- CAS Key Laboratory of Tropical Plant Resources and Sustainable Use, The Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan, 666303, China
| | - Yangwen Qian
- WIMI Biotechnology Co. Ltd., Changzhou, 213000, China
| | - Qingjun Xie
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Key Laboratory for Enhancing Resource Use Efficiency of Crops in South China, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Plant Molecular Breeding, College of Agriculture, South China Agricultural University, Guangzhou, 510642, China
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27
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Broadbent DG, McEwan CM, Tsang TM, Poole DM, Naylor BC, Price JC, Schmidt JC, Andersen JL. The formation of ubiquitin rich condensates triggers recruitment of the ATG9A lipid transfer complex to initiate basal autophagy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.28.569058. [PMID: 38077022 PMCID: PMC10705457 DOI: 10.1101/2023.11.28.569058] [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] [Indexed: 12/20/2023]
Abstract
Autophagy is an essential cellular recycling process that maintains protein and organelle homeostasis. ATG9A vesicle recruitment is a critical early step in autophagy to initiate autophagosome biogenesis. The mechanisms of ATG9A vesicle recruitment are best understood in the context of starvation-induced non-selective autophagy, whereas less is known about the signals driving ATG9A vesicle recruitment to autophagy initiation sites in the absence of nutrient stress. Here we demonstrate that loss of ATG9A or the lipid transfer protein ATG2 leads to the accumulation of phosphorylated p62 aggregates in the context of basal autophagy. Furthermore, we show that p62 degradation requires the lipid scramblase activity of ATG9A. Lastly, we present evidence that poly-ubiquitin is an essential signal that recruits ATG9A and mediates autophagy foci assembly in nutrient replete cells. Together, our data support a ubiquitin-driven model of ATG9A recruitment and autophagosome formation during basal autophagy.
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Affiliation(s)
- D G Broadbent
- Institute for Quantitative Health Sciences and Engineering, Michigan State University, East Lansing, MI, USA
- College of Osteopathic Medicine, Michigan State University, East Lansing, MI, USA
- Department of Physiology, College of Natural Sciences, Michigan State University, East Lansing, MI, USA
| | - C M McEwan
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, USA
| | - T M Tsang
- Institute for Quantitative Health Sciences and Engineering, Michigan State University, East Lansing, MI, USA
- College of Osteopathic Medicine, Michigan State University, East Lansing, MI, USA
- Department of Physiology, College of Natural Sciences, Michigan State University, East Lansing, MI, USA
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, USA
- Department of Obstetrics, Gynecology, and Reproductive Biology, Michigan State University, East Lansing, MI, USA
- Department of Oncological Sciences and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - D M Poole
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, USA
| | - B C Naylor
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, USA
| | - J C Price
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, USA
| | - J C Schmidt
- Institute for Quantitative Health Sciences and Engineering, Michigan State University, East Lansing, MI, USA
- Department of Obstetrics, Gynecology, and Reproductive Biology, Michigan State University, East Lansing, MI, USA
| | - J L Andersen
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, USA
- Department of Oncological Sciences and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT, USA
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28
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Barnaba C, Broadbent DG, Perez GI, Schmidt JC. AMPK Regulates Phagophore-to-Autophagosome Maturation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.28.559981. [PMID: 37808644 PMCID: PMC10557706 DOI: 10.1101/2023.09.28.559981] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Autophagy is an important metabolic pathway that can non-selectively recycle cellular material or lead to targeted degradation of protein aggregates or damaged organelles. Autophagosome formation starts with autophagy factors accumulating on lipid vesicles containing ATG9. These phagophores attach to donor membranes, expand via ATG2-mediated lipid transfer, capture cargo, and mature into autophagosomes, ultimately fusing with lysosomes for their degradation. Autophagy can be activated by nutrient stress, for example by a reduction in the cellular levels of amino acids. In contrast, how autophagy is regulated by low cellular ATP levels via the AMP-activated protein kinase (AMPK), an important therapeutic target, is less clear. Using live-cell imaging and an automated image analysis pipeline, we systematically dissect how nutrient starvation regulates autophagosome biogenesis. We demonstrate that glucose starvation downregulates autophagosome maturation by AMPK mediated inhibition of phagophores tethering to donor membranes. Our results clarify AMPK's regulatory role in autophagy and highlight its potential as a therapeutic target to reduce autophagy.
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Affiliation(s)
- Carlo Barnaba
- Institute for Quantitative Health Science and Engineering
| | - David G. Broadbent
- Institute for Quantitative Health Science and Engineering
- College of Osteopathic Medicine
- Department of Physiology
| | | | - Jens C. Schmidt
- Institute for Quantitative Health Science and Engineering
- Department of Obstetrics, Gynecology and Reproductive Biology, Michigan State University, East Lansing, USA
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29
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Deretic V. Atg8ylation as a host-protective mechanism against Mycobacterium tuberculosis. FRONTIERS IN TUBERCULOSIS 2023; 1:1275882. [PMID: 37901138 PMCID: PMC10612523 DOI: 10.3389/ftubr.2023.1275882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/31/2023]
Abstract
Nearly two decades have passed since the first report on autophagy acting as a cell-autonomous defense against Mycobacterium tuberculosis. This helped usher a new area of research within the field of host-pathogen interactions and led to the recognition of autophagy as an immunological mechanism. Interest grew in the fundamental mechanisms of antimicrobial autophagy and in the prophylactic and therapeutic potential for tuberculosis. However, puzzling in vivo data have begun to emerge in murine models of M. tuberculosis infection. The control of infection in mice affirmed the effects of certain autophagy genes, specifically ATG5, but not of other ATGs. Recent studies with a more complete inactivation of ATG genes now show that multiple ATG genes are indeed necessary for protection against M. tuberculosis. These particular ATG genes are involved in the process of membrane atg8ylation. Atg8ylation in mammalian cells is a broad response to membrane stress, damage and remodeling of which canonical autophagy is one of the multiple downstream outputs. The current developments clarify the controversies and open new avenues for both fundamental and translational studies.
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Affiliation(s)
- Vojo Deretic
- Autophagy, Inflammation and Metabolism Center of Biochemical Research Excellence
- Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, 915 Camino de Salud, NE, Albuquerque, NM 87131, USA
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30
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Melia TJ. Growing thin - How bulk lipid transport drives expansion of the autophagosome membrane but not of its lumen. Curr Opin Cell Biol 2023; 83:102190. [PMID: 37385155 PMCID: PMC10528516 DOI: 10.1016/j.ceb.2023.102190] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 05/30/2023] [Accepted: 05/30/2023] [Indexed: 07/01/2023]
Abstract
The key event in macroautophagy is the de novo formation of a new organelle called the autophagosome which when complete, will have captured bits of cytoplasm within its double-membrane structure. Eventual fusion with the lysosome allows this captured material to be degraded back to simple molecules which can be recycled to support cell function during starvation. How autophagosomes form has been a challenging question for over 60 years. This review highlights work that forms the basis for an autophagosome membrane expansion model grounded in protein-mediated lipid transport.
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31
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Wallace NS, Gadbery JE, Cohen CI, Kendall AK, Jackson LP. Tepsin binds LC3B to promote ATG9A export and delivery at the cell periphery. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.18.549521. [PMID: 37502979 PMCID: PMC10370099 DOI: 10.1101/2023.07.18.549521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Tepsin is an established accessory protein found in Adaptor Protein 4 (AP-4) coated vesicles, but the biological role of tepsin remains unknown. AP-4 vesicles originate at the trans -Golgi network (TGN) and target the delivery of ATG9A, a scramblase required for autophagosome biogenesis, to the cell periphery. Using in silico methods, we identified a putative L C3-Interacting R egion (LIR) motif in tepsin. Biochemical experiments using purified recombinant proteins indicate tepsin directly binds LC3B, but not other members, of the mammalian ATG8 family. Calorimetry and structural modeling data indicate this interaction occurs with micromolar affinity using the established LC3B LIR docking site. Loss of tepsin in cultured cells dysregulates ATG9A export from the TGN as well as ATG9A distribution at the cell periphery. Tepsin depletion in a mRFP-GFP-LC3B HeLa reporter cell line using siRNA knockdown increases autophagosome volume and number, but does not appear to affect flux through the autophagic pathway. Re-introduction of wild-type tepsin partially rescues ATG9A cargo trafficking defects. In contrast, re-introducing tepsin with a mutated LIR motif or missing N-terminus does not fully rescue altered ATG9A subcellular distribution. Together, these data suggest roles for tepsin in cargo export from the TGN; delivery of ATG9A-positive vesicles at the cell periphery; and in overall maintenance of autophagosome structure.
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32
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Abstract
Two papers in this issue resolve a long-standing obstacle to a "standard model" for autophagosome biogenesis in mammals. The first, Olivas et al. (2023. J. Cell Biol. https://doi.org/10.1083/jcb.202208088), uses biochemistry to confirm that the lipid scramblase ATG9A is a bona fide autophagosome component, while the second, Broadbent et al. (2023. J. Cell Biol. https://doi.org/10.1083/jcb.202210078), uses particle tracking to show that the dynamics of autophagy proteins are consistent with the concept.
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Affiliation(s)
- Annan S.I. Cook
- Graduate Group in Biophysics, University of California, Berkeley, Berkeley, CA, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA, USA
- Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD, USA
| | - James H. Hurley
- Graduate Group in Biophysics, University of California, Berkeley, Berkeley, CA, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA, USA
- Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD, USA
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, USA
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33
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Nita M, Grzybowski A. Antioxidative Role of Heterophagy, Autophagy, and Mitophagy in the Retina and Their Association with the Age-Related Macular Degeneration (AMD) Etiopathogenesis. Antioxidants (Basel) 2023; 12:1368. [PMID: 37507908 PMCID: PMC10376332 DOI: 10.3390/antiox12071368] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 06/09/2023] [Accepted: 06/26/2023] [Indexed: 07/30/2023] Open
Abstract
Age-related macular degeneration (AMD), an oxidative stress-linked neurodegenerative disease, leads to irreversible damage of the central retina and severe visual impairment. Advanced age and the long-standing influence of oxidative stress and oxidative cellular damage play crucial roles in AMD etiopathogenesis. Many authors emphasize the role of heterophagy, autophagy, and mitophagy in maintaining homeostasis in the retina. Relevantly modifying the activity of both macroautophagy and mitophagy pathways represents one of the new therapeutic strategies in AMD. Our review provides an overview of the antioxidative roles of heterophagy, autophagy, and mitophagy and presents associations between dysregulations of these molecular mechanisms and AMD etiopathogenesis. The authors performed an extensive analysis of the literature, employing PubMed and Google Scholar, complying with the 2013-2023 period, and using the following keywords: age-related macular degeneration, RPE cells, reactive oxygen species, oxidative stress, heterophagy, autophagy, and mitophagy. Heterophagy, autophagy, and mitophagy play antioxidative roles in the retina; however, they become sluggish and dysregulated with age and contribute to AMD development and progression. In the retina, antioxidative roles also play in RPE cells, NFE2L2 and PGC-1α proteins, NFE2L2/PGC-1α/ARE signaling cascade, Nrf2 factor, p62/SQSTM1/Keap1-Nrf2/ARE pathway, circulating miRNAs, and Yttrium oxide nanoparticles performed experimentally in animal studies.
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Affiliation(s)
- Małgorzata Nita
- Domestic and Specialized Medicine Centre "Dilmed", 40-231 Katowice, Poland
| | - Andrzej Grzybowski
- Institute for Research in Ophthalmology, Foundation for Ophthalmology Development, Gorczyczewskiego 2/3, 61-553 Poznań, Poland
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