101
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Mookherjee D, Das S, Mukherjee R, Bera M, Jana SC, Chakrabarti S, Chakrabarti O. RETREG1/FAM134B mediated autophagosomal degradation of AMFR/GP78 and OPA1 -a dual organellar turnover mechanism. Autophagy 2020; 17:1729-1752. [PMID: 32559118 DOI: 10.1080/15548627.2020.1783118] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Turnover of cellular organelles, including endoplasmic reticulum (ER) and mitochondria, is orchestrated by an efficient cellular surveillance system. We have identified a mechanism for dual regulation of ER and mitochondria under stress. It is known that AMFR, an ER E3 ligase and ER-associated degradation (ERAD) regulator, degrades outer mitochondrial membrane (OMM) proteins, MFNs (mitofusins), via the proteasome and triggers mitophagy. We show that destabilized mitochondria are almost devoid of the OMM and generate "mitoplasts". This brings the inner mitochondrial membrane (IMM) in the proximity of the ER. When AMFR levels are high and the mitochondria are stressed, the reticulophagy regulatory protein RETREG1 participates in the formation of the mitophagophore by interacting with OPA1. Interestingly, OPA1 and other IMM proteins exhibit similar RETREG1-dependent autophagosomal degradation as AMFR, unlike most of the OMM proteins. The "mitoplasts" generated are degraded by reticulo-mito-phagy - simultaneously affecting dual organelle turnover.Abbreviations: AMFR/GP78: autocrine motility factor receptor; BAPTA: 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; BFP: blue fluorescent protein; CCCP: carbonyl cyanide m-chlorophenyl hydrazone; CNBr: cyanogen bromide; ER: endoplasmic reticulum; ERAD: endoplasmic-reticulum-associated protein degradation; FL: fluorescence, GFP: green fluorescent protein; HA: hemagglutinin; HEPES: 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid; IMM: inner mitochondrial membrane; LIR: LC3-interacting region; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MFN: mitofusin, MGRN1: mahogunin ring finger 1; NA: numerical aperature; OMM: outer mitochondrial membrane; OPA1: OPA1 mitochondrial dynamin like GTPase; PRNP/PrP: prion protein; RER: rough endoplasmic reticulum; RETREG1/FAM134B: reticulophagy regulator 1; RFP: red fluorescent protein; RING: really interesting new gene; ROI: region of interest; RTN: reticulon; SEM: standard error of the mean; SER: smooth endoplasmic reticulum; SIM: structured illumination microscopy; SQSTM1/p62: sequestosome 1; STED: stimulated emission depletion; STOML2: stomatin like 2; TOMM20: translocase of outer mitochondrial membrane 20; UPR: unfolded protein response.
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Affiliation(s)
- Debdatto Mookherjee
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata, India
| | - Subhrangshu Das
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Rukmini Mukherjee
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata, India.,Buchmann Institute for Molecular Life Sciences, Frankfurt Am Main, Germany
| | - Manindra Bera
- Laboratory of Cell Biology, the Rockefeller University, New York, USA
| | | | - Saikat Chakrabarti
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Oishee Chakrabarti
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata, India.,Homi Bhabha National Institute, Mumbai, India
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102
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Huang S, Tang M, Jiang H, Li Y, Hu H. A COPII subunit interacting with ER-phagy receptor: a new potential avenue to maintaining neuronal homeostasis. Acta Biochim Biophys Sin (Shanghai) 2020; 52:698-700. [PMID: 32348448 DOI: 10.1093/abbs/gmaa031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Revised: 11/19/2019] [Accepted: 11/07/2019] [Indexed: 11/12/2022] Open
Affiliation(s)
- Shifang Huang
- Department of Pharmacology, Yongzhou Vocational Technical College, Yongzhou 425000, China
| | - Mingzhu Tang
- Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Honglu Jiang
- Department of Pharmacology, Yongzhou Radio and TV University, Yongzhou 425000, China
| | - Yuting Li
- Department of Pharmacology, Yongzhou Vocational Technical College, Yongzhou 425000, China
| | - Haoliang Hu
- Department of Pharmacology, Yongzhou Vocational Technical College, Yongzhou 425000, China
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103
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Nakashima A, Shima T, Tsuda S, Aoki A, Kawaguchi M, Yoneda S, Yamaki-Ushijima A, Cheng SB, Sharma S, Saito S. Disruption of Placental Homeostasis Leads to Preeclampsia. Int J Mol Sci 2020; 21:ijms21093298. [PMID: 32392703 PMCID: PMC7246800 DOI: 10.3390/ijms21093298] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 04/29/2020] [Accepted: 05/04/2020] [Indexed: 12/12/2022] Open
Abstract
Placental homeostasis is directly linked to fetal well-being and normal fetal growth. Placentas are sensitive to various environmental stressors, including hypoxia, endoplasmic reticulum stress, and oxidative stress. Once placental homeostasis is disrupted, the placenta may rebel against the mother and fetus. Autophagy is an evolutionally conservative mechanism for the maintenance of cellular and organic homeostasis. Evidence suggests that autophagy plays a crucial role throughout pregnancy, including fertilization, placentation, and delivery in human and mouse models. This study reviews the available literature discussing the role of autophagy in preeclampsia.
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Affiliation(s)
- Akitoshi Nakashima
- Department of Obstetrics and Gynecology, University of Toyama, Toyama 930-8555, Japan; (T.S.); (S.T.); (A.A.); (M.K.); (S.Y.); (A.Y.-U.); (S.S.)
- Correspondence: ; Tel.: +81-76-434-7355
| | - Tomoko Shima
- Department of Obstetrics and Gynecology, University of Toyama, Toyama 930-8555, Japan; (T.S.); (S.T.); (A.A.); (M.K.); (S.Y.); (A.Y.-U.); (S.S.)
| | - Sayaka Tsuda
- Department of Obstetrics and Gynecology, University of Toyama, Toyama 930-8555, Japan; (T.S.); (S.T.); (A.A.); (M.K.); (S.Y.); (A.Y.-U.); (S.S.)
| | - Aiko Aoki
- Department of Obstetrics and Gynecology, University of Toyama, Toyama 930-8555, Japan; (T.S.); (S.T.); (A.A.); (M.K.); (S.Y.); (A.Y.-U.); (S.S.)
| | - Mihoko Kawaguchi
- Department of Obstetrics and Gynecology, University of Toyama, Toyama 930-8555, Japan; (T.S.); (S.T.); (A.A.); (M.K.); (S.Y.); (A.Y.-U.); (S.S.)
| | - Satoshi Yoneda
- Department of Obstetrics and Gynecology, University of Toyama, Toyama 930-8555, Japan; (T.S.); (S.T.); (A.A.); (M.K.); (S.Y.); (A.Y.-U.); (S.S.)
| | - Akemi Yamaki-Ushijima
- Department of Obstetrics and Gynecology, University of Toyama, Toyama 930-8555, Japan; (T.S.); (S.T.); (A.A.); (M.K.); (S.Y.); (A.Y.-U.); (S.S.)
| | - Shi-Bin Cheng
- Department of Pediatrics, Women and Infants Hospital of Rhode Island, Warren Alpert Medical School of Brown University, Providence, RI 02903, USA; (S.-B.C.); (S.S.)
| | - Surendra Sharma
- Department of Pediatrics, Women and Infants Hospital of Rhode Island, Warren Alpert Medical School of Brown University, Providence, RI 02903, USA; (S.-B.C.); (S.S.)
| | - Shigeru Saito
- Department of Obstetrics and Gynecology, University of Toyama, Toyama 930-8555, Japan; (T.S.); (S.T.); (A.A.); (M.K.); (S.Y.); (A.Y.-U.); (S.S.)
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104
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Li Z, Huang W, Wang W. Multifaceted roles of COPII subunits in autophagy. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1867:118627. [DOI: 10.1016/j.bbamcr.2019.118627] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 12/09/2019] [Accepted: 12/14/2019] [Indexed: 01/06/2023]
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105
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Liu J, Kuang F, Kroemer G, Klionsky DJ, Kang R, Tang D. Autophagy-Dependent Ferroptosis: Machinery and Regulation. Cell Chem Biol 2020; 27:420-435. [PMID: 32160513 DOI: 10.1016/j.chembiol.2020.02.005] [Citation(s) in RCA: 555] [Impact Index Per Article: 111.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 01/19/2020] [Accepted: 02/19/2020] [Indexed: 12/20/2022]
Abstract
Macroautophagy (hereafter referred to as autophagy) is an evolutionarily conserved cellular process capable of degrading various biological molecules (e.g., protein, glycogen, lipids, DNA, and RNA) and organelles (e.g., mitochondria, endoplasmic reticulum [ER] ribosomes, lysosomes, and micronuclei) via the lysosomal pathway. Ferroptosis is a type of oxidative stress-dependent regulated cell death associated with iron accumulation and lipid peroxidation. The recently discovered role of autophagy, especially selective types of autophagy (e.g., ferritinophagy, lipophagy, clockophagy, and chaperone-mediated autophagy), in driving cells toward ferroptotic death motivated us to explore the functional interactions between metabolism, immunity, and cell death. Here, we describe types of selective autophagy and discuss the regulatory mechanisms and signaling pathways of autophagy-dependent ferroptosis. We also summarize chemical modulators that are currently available for triggering or blocking autophagy-dependent ferroptosis and that may be developed for therapeutic interventions in human diseases.
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Affiliation(s)
- Jiao Liu
- The Third Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510600, China
| | - Feimei Kuang
- The Third Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510600, China
| | - Guido Kroemer
- Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France; Equipe 11 Labellisée Ligue Nationale Contre le Cancer, Centre de Recherche des Cordeliers, 75006 Paris, France; Institut National de la Santé et de la Recherche Médicale, U1138, Paris, France; Université Pierre et Marie Curie, 75006 Paris, France; Metabolomics and Cell Biology Platforms, Gustave Roussy Cancer Campus, 94800 Villejuif, France; Pôle de Biologie, Hôpital Européen Georges Pompidou, AP-HP, 75015 Paris, France; Department of Women's and Children's Health, Karolinska University Hospital, 17176 Stockholm, Sweden
| | - Daniel J Klionsky
- Life Sciences Institute and Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Rui Kang
- Department of Surgery, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Daolin Tang
- The Third Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510600, China; Department of Surgery, UT Southwestern Medical Center, Dallas, TX 75390, USA.
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106
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ER-Phagy: Quality Control and Turnover of Endoplasmic Reticulum. Trends Cell Biol 2020; 30:384-398. [PMID: 32302550 DOI: 10.1016/j.tcb.2020.02.001] [Citation(s) in RCA: 200] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 01/30/2020] [Accepted: 02/03/2020] [Indexed: 12/11/2022]
Abstract
The endoplasmic reticulum (ER) is the largest organelle in cells and has fundamental functions, such as folding, processing, and trafficking of proteins, cellular metabolism, and ion storage. To maintain its function, it is turned over constitutively, and even more actively under certain stress conditions. Quality control of the ER is mediated primarily by two pathways: the ubiquitin-proteasome system and autophagy (termed 'ER-phagy'). The identification of ER-phagy adaptor molecules has shed light on the mechanisms and physiological significance of ER-phagy. Here, we describe recent findings on various types of ER-phagy and present unanswered questions related to their mechanism and regulation.
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107
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De Leonibus C, Cinque L, Settembre C. Beating the ER: novel insights into FAM134B function and regulation. EMBO J 2020; 39:e104546. [PMID: 32073155 PMCID: PMC7049802 DOI: 10.15252/embj.2020104546] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
To maintain cellular homeostasis, the endoplasmic reticulum (ER) necessitates a continuous removal of ER fragments via a selective, receptor‐mediated, form of autophagy known as ER‐phagy. In this issue of The EMBO Journal, Jiang et al (2020) shed light on how the best characterized autophagy receptor FAM134B mediates ER membrane fragmentation, the earliest event during ER‐phagy. They propose a dynamic model for FAM134B protein oligomerization and ER membrane scission, which are driven by CAMK2B‐mediated phosphorylation of the receptor and are altered in sensory neuropathy.
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Affiliation(s)
| | - Laura Cinque
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy
| | - Carmine Settembre
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy.,Department of Medical and Translational Science, University of Naples "Federico II", Naples, Italy
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108
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Zhang X, Ding X, Marshall RS, Paez-Valencia J, Lacey P, Vierstra RD, Otegui MS. Reticulon proteins modulate autophagy of the endoplasmic reticulum in maize endosperm. eLife 2020; 9:51918. [PMID: 32011236 PMCID: PMC7046470 DOI: 10.7554/elife.51918] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 02/02/2020] [Indexed: 12/18/2022] Open
Abstract
Reticulon (Rtn) proteins shape tubular domains of the endoplasmic reticulum (ER), and in some cases are autophagy receptors for selective ER turnover. We have found that maize Rtn1 and Rtn2 control ER homeostasis and autophagic flux in endosperm aleurone cells, where the ER accumulates lipid droplets and synthesizes storage protein accretions metabolized during germination. Maize Rtn1 and Rtn2 are expressed in the endosperm, localize to the ER, and re-model ER architecture in a dose-dependent manner. Rtn1 and Rtn2 interact with Atg8a using four Atg8-interacting motifs (AIMs) located at the C-terminus, cytoplasmic loop, and within the transmembrane segments. Binding between Rtn2 and Atg8 is elevated upon ER stress. Maize rtn2 mutants display increased autophagy and up-regulation of an ER stress-responsive chaperone. We propose that maize Rtn1 and Rtn2 act as receptors for autophagy-mediated ER turnover, and thus are critical for ER homeostasis and suppression of ER stress.
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Affiliation(s)
- Xiaoguo Zhang
- Department of Botany, Laboratory of Cell and Molecular Biology, University of Wisconsin, Madison, United States
| | - Xinxin Ding
- Department of Botany, Laboratory of Cell and Molecular Biology, University of Wisconsin, Madison, United States
| | | | - Julio Paez-Valencia
- Department of Botany, Laboratory of Cell and Molecular Biology, University of Wisconsin, Madison, United States
| | - Patrick Lacey
- Department of Botany, Laboratory of Cell and Molecular Biology, University of Wisconsin, Madison, United States
| | | | - Marisa S Otegui
- Department of Botany, Laboratory of Cell and Molecular Biology, University of Wisconsin, Madison, United States.,Department of Genetics, University of Wisconsin, Madison, United States
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109
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Beese CJ, Brynjólfsdóttir SH, Frankel LB. Selective Autophagy of the Protein Homeostasis Machinery: Ribophagy, Proteaphagy and ER-Phagy. Front Cell Dev Biol 2020; 7:373. [PMID: 32039200 PMCID: PMC6985035 DOI: 10.3389/fcell.2019.00373] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 12/16/2019] [Indexed: 01/06/2023] Open
Abstract
The eukaryotic cell has developed intricate machineries that monitor and maintain proteome homeostasis in order to ensure cellular functionality. This involves the carefully coordinated balance between protein synthesis and degradation pathways, which are dynamically regulated in order to meet the constantly changing demands of the cell. Ribosomes, together with the endoplasmic reticulum (ER), are the key drivers of protein synthesis, folding, maturation and sorting, while the proteasome plays a pivotal role in terminating the existence of thousands of proteins that are misfolded, damaged or otherwise obsolete. The synthesis, structure and function of these dedicated machines has been studied for decades, however, much less is understood about the mechanisms that control and execute their own turnover. Autophagy, an evolutionarily conserved catabolic pathway, mediates degradation of a large variety of cytosolic substrates, ranging from single proteins to entire organelles or multi-subunit macromolecular complexes. In this review, we focus on selective autophagy of three key components of the protein homeostasis machinery: ribosomes, ER and proteasomes, through the selective autophagy pathways of ribophagy, ER-phagy, and proteaphagy. We discuss newly discovered mechanisms for the selective clearance of these substrates, which are often stress-dependent and involve specialized signals for cargo recognition by a growing number of receptors. We further discuss the interplay between these pathways and their biological impact on key aspects of proteome homeostasis and cellular function in health and disease.
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Affiliation(s)
- Carsten J Beese
- Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen, Denmark.,Danish Cancer Society Research Center, Copenhagen, Denmark
| | | | - Lisa B Frankel
- Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen, Denmark.,Danish Cancer Society Research Center, Copenhagen, Denmark
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110
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NAKATOGAWA H. Autophagic degradation of the endoplasmic reticulum. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2020; 96:1-9. [PMID: 31932525 PMCID: PMC6974406 DOI: 10.2183/pjab.96.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 10/11/2019] [Indexed: 06/10/2023]
Abstract
Autophagy is an intracellular degradation system that is present in most eukaryotes. In the process of autophagy, double membrane vesicles called autophagosomes sequester a wide variety of cellular constituents and deliver them to lytic organelles: lysosomes in mammals and vacuoles in yeast and plants. Although autophagy used to be considered a non-selective process in its target sequestration into autophagosomes, recent studies have revealed that autophagosomes can also selectively sequester certain proteins and organelles that have become unnecessary or harmful for the cell. We recently discovered that the endoplasmic reticulum (ER) is degraded by autophagy in a selective manner in the budding yeast Saccharomyces cerevisiae, and identified "receptor proteins" that play pivotal roles in this "ER-phagy" pathway. Moreover, several ER-phagy receptors in mammalian cells have also been reported. This report provides an overview of our current knowledge on ER-phagy and discuss their mechanisms, physiological roles, and possible links to human diseases.
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Affiliation(s)
- Hitoshi NAKATOGAWA
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Kanagawa, Japan
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111
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Wang H, Liu R. Macrophage Migration Inhibitory Factor: New Insights into the Pathogenesis of Alcoholic Liver Disease. Alcohol Clin Exp Res 2020; 44:19-22. [PMID: 31634420 DOI: 10.1111/acer.14220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 10/16/2019] [Indexed: 11/29/2022]
Affiliation(s)
- Hua Wang
- Department of Oncology, the First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Rui Liu
- Department of Oncology, the First Affiliated Hospital of Anhui Medical University, Hefei, China
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112
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Abstract
In consistent with other membrane-bound and secretory proteins, immune checkpoint proteins go through a set of modifications in the endoplasmic reticulum (ER) to acquire their native functional structures before they function at their destinations. There are various ER-resident chaperones and enzymes synergistically regulate and catalyze the glycosylation, folding and transporting of proteins. The whole processing is under the surveillance of ER quality control system which allows the correctly folded proteins to exit from the ER with the help of coat proteinII(COPII) coated vesicles, while retains the rest of terminally misfolded ones in the ER and then eliminates them via ER-associated degradation (ERAD) or ER-to-lysosomes-associated degradation (ERLAD). The dysfunction of the ER causes ER stress which triggers unfolded protein response (UPR) to restore ER proteostasis. Unsolvable prolonged ER stress ultimately results in cell death. This chapter reviews the process that proteins undergo in the ER, and the glycosylation, folding and degradation of immune checkpoint proteins as well as the associated potential immunotherapies to date.
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113
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Tang BL. Syntaxin 16's Newly Deciphered Roles in Autophagy. Cells 2019; 8:1655. [PMID: 31861136 PMCID: PMC6953085 DOI: 10.3390/cells8121655] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 12/05/2019] [Accepted: 12/06/2019] [Indexed: 12/16/2022] Open
Abstract
Syntaxin 16, a Qa-SNARE (soluble N-ethylmaleimide-sensitive factor activating protein receptor), is involved in a number of membrane-trafficking activities, particularly transport processes at the trans-Golgi network (TGN). Recent works have now implicated syntaxin 16 in the autophagy process. In fact, syntaxin 16 appears to have dual roles, firstly in facilitating the transport of ATG9a-containing vesicles to growing autophagosomes, and secondly in autolysosome formation. The former involves a putative SNARE complex between syntaxin 16, VAMP7 and SNAP-47. The latter occurs via syntaxin 16's recruitment by Atg8/LC3/GABARAP family proteins to autophagosomes and endo-lysosomes, where syntaxin 16 may act in a manner that bears functional redundancy with the canonical autophagosome Qa-SNARE syntaxin 17. Here, I discuss these recent findings and speculate on the mechanistic aspects of syntaxin 16's newly found role in autophagy.
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Affiliation(s)
- Bor Luen Tang
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117596, Singapore; ; Tel.: +65-6516-1040
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 119077, Singapore
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114
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Stolz A, Grumati P. The various shades of ER-phagy. FEBS J 2019; 286:4642-4649. [PMID: 31386802 PMCID: PMC6916603 DOI: 10.1111/febs.15031] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 07/16/2019] [Accepted: 08/02/2019] [Indexed: 12/18/2022]
Abstract
Endoplasmic reticulum (ER) is a large and dynamic cellular organelle. ER morphology consists of sheets, tubules, matrixes, and contact sites shared with other membranous organelles. The capacity of the ER to fulfill its numerous biological functions depends on its continuous remodeling and the quality control of its proteome. Selective turnover of the ER by autophagy, termed ER-phagy, plays an important role in maintaining ER homeostasis. ER network integrity and turnover rely on specific ER-phagy receptors, which influence and coordinate alterations in ER morphology and the degradation of ER contents and membranes via the lysosome, by interacting with the LC3/GABARAP family. In this commentary, we discuss general principles and identify the major players in this recently characterized form of selective autophagy, while simultaneously highlighting open questions in the field.
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Affiliation(s)
- Alexandra Stolz
- Structural Genomics Consortium, BMLSGoethe UniversityFrankfurtGermany
- Institute of Biochemistry 2Goethe University School of MedicineFrankfurtGermany
| | - Paolo Grumati
- Telethon Institute of Genetics and Medicine (TIGEM)PozzuoliItaly
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115
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Pohl C, Dikic I. Cellular quality control by the ubiquitin-proteasome system and autophagy. Science 2019; 366:818-822. [DOI: 10.1126/science.aax3769] [Citation(s) in RCA: 352] [Impact Index Per Article: 58.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
To achieve homeostasis, cells evolved dynamic and self-regulating quality control processes to adapt to new environmental conditions and to prevent prolonged damage. We discuss the importance of two major quality control systems responsible for degradation of proteins and organelles in eukaryotic cells: the ubiquitin-proteasome system (UPS) and autophagy. The UPS and autophagy form an interconnected quality control network where decision-making is self-organized on the basis of biophysical parameters (binding affinities, local concentrations, and avidity) and compartmentalization (through membranes, liquid-liquid phase separation, or the formation of aggregates). We highlight cellular quality control factors that delineate their differential deployment toward macromolecular complexes, liquid-liquid phase-separated subcellular structures, or membrane-bound organelles. Finally, we emphasize the need for continuous promotion of quantitative and mechanistic research into the roles of the UPS and autophagy in human pathophysiology.
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Affiliation(s)
- Christian Pohl
- Institute of Biochemistry II, Faculty of Medicine, Goethe University, 60590 Frankfurt am Main, Germany
- Buchmann Institute for Molecular Life Sciences, Goethe University, 60438 Frankfurt am Main, Germany
| | - Ivan Dikic
- Institute of Biochemistry II, Faculty of Medicine, Goethe University, 60590 Frankfurt am Main, Germany
- Buchmann Institute for Molecular Life Sciences, Goethe University, 60438 Frankfurt am Main, Germany
- Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
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116
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Loi M, Raimondi A, Morone D, Molinari M. ESCRT-III-driven piecemeal micro-ER-phagy remodels the ER during recovery from ER stress. Nat Commun 2019; 10:5058. [PMID: 31699981 PMCID: PMC6838186 DOI: 10.1038/s41467-019-12991-z] [Citation(s) in RCA: 103] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 10/10/2019] [Indexed: 12/13/2022] Open
Abstract
The endoplasmic reticulum (ER) produces about 40% of the nucleated cell's proteome. ER size and content in molecular chaperones increase upon physiologic and pathologic stresses on activation of unfolded protein responses (UPR). On stress resolution, the mammalian ER is remodeled to pre-stress, physiologic size and function on activation of the LC3-binding activity of the translocon component SEC62. This elicits recov-ER-phagy, i.e., the delivery of the excess ER generated during the phase of stress to endolysosomes (EL) for clearance. Here, ultrastructural and genetic analyses reveal that recov-ER-phagy entails the LC3 lipidation machinery and proceeds via piecemeal micro-ER-phagy, where RAB7/LAMP1-positive EL directly engulf excess ER in processes that rely on the Endosomal Sorting Complex Required for Transport (ESCRT)-III component CHMP4B and the accessory AAA+ ATPase VPS4A. Thus, ESCRT-III-driven micro-ER-phagy emerges as a key catabolic pathway activated to remodel the mammalian ER on recovery from ER stress.
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Affiliation(s)
- Marisa Loi
- Faculty of Biomedical Sciences, Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Bellinzona, Switzerland
- Department of Biology, Swiss Federal Institute of Technology, 8093, Zurich, Switzerland
| | - Andrea Raimondi
- Experimental Imaging Center, San Raffaele Scientific Institute, 20132, Milan, Italy
| | - Diego Morone
- Faculty of Biomedical Sciences, Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Bellinzona, Switzerland
| | - Maurizio Molinari
- Faculty of Biomedical Sciences, Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Bellinzona, Switzerland.
- School of Life Sciences, École Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland.
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117
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ER-phagy and human diseases. Cell Death Differ 2019; 27:833-842. [PMID: 31659280 DOI: 10.1038/s41418-019-0444-0] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 10/04/2019] [Accepted: 10/11/2019] [Indexed: 12/27/2022] Open
Abstract
Autophagy regulates the degradation of unnecessary or dysfunctional cellular components. This catabolic process requires the formation of a double-membrane vesicle, the autophagosome, that engulfs the cytosolic material and delivers it to the lysosome. Substrate specificity is achieved by autophagy receptors, which are characterized by the presence of at least one LC3-interaction region (LIR) or GABARAP-interaction motif (GIM). Only recently, several receptors that mediate the specific degradation of endoplasmic reticulum (ER) components via autophagy have been identified (the process known as ER-phagy or reticulophagy). Here, we give an update on the current knowledge about the role of ER-phagy receptors in health and disease.
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118
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Staiano L, Zappa F. Hijacking intracellular membranes to feed autophagosomal growth. FEBS Lett 2019; 593:3120-3134. [PMID: 31603532 DOI: 10.1002/1873-3468.13637] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 10/02/2019] [Accepted: 10/03/2019] [Indexed: 12/21/2022]
Abstract
Autophagy is widely considered as a housekeeping mechanism that enables cells to survive stress conditions and, in particular, nutrient deprivation. Autophagy begins with the formation of the phagophore that expands and closes around cytosolic material and damaged organelles destined for degradation. The execution of this complex machinery is guaranteed by the coordinated action of more than 40 ATG (autophagy-related) proteins that control the entire process at different stages from the biogenesis of the autophagosome to cargo sequestration and fusion with lysosomes. Autophagosome biogenesis occurs at multiple intracellular sites, such as the endoplasmic reticulum (ER) and the plasma membrane. Soon after the formation of the phagophore, the nascent autophagosome progressively grows in size and ultimately closes by recruiting intracellular membranes. In this review, we focus on the contribution of three membrane sources - the ER, the ER-Golgi intermediate compartment, and the Golgi complex - to autophagosome biogenesis and expansion. We also highlight the interplay between the secretory pathway and autophagy in cells when nutrients are scarce.
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Affiliation(s)
- Leopoldo Staiano
- Telethon Institute of Genetics and Medicine, Pozzuoli, Naples, Italy
| | - Francesca Zappa
- Telethon Institute of Genetics and Medicine, Pozzuoli, Naples, Italy.,Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, USA
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119
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Sun Z, Brodsky JL. Protein quality control in the secretory pathway. J Cell Biol 2019; 218:3171-3187. [PMID: 31537714 PMCID: PMC6781448 DOI: 10.1083/jcb.201906047] [Citation(s) in RCA: 262] [Impact Index Per Article: 43.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 07/22/2019] [Accepted: 08/29/2019] [Indexed: 12/23/2022] Open
Abstract
Protein folding is inherently error prone, especially in the endoplasmic reticulum (ER). Even with an elaborate network of molecular chaperones and protein folding facilitators, misfolding can occur quite frequently. To maintain protein homeostasis, eukaryotes have evolved a series of protein quality-control checkpoints. When secretory pathway quality-control pathways fail, stress response pathways, such as the unfolded protein response (UPR), are induced. In addition, the ER, which is the initial hub of protein biogenesis in the secretory pathway, triages misfolded proteins by delivering substrates to the proteasome or to the lysosome/vacuole through ER-associated degradation (ERAD) or ER-phagy. Some misfolded proteins escape the ER and are instead selected for Golgi quality control. These substrates are targeted for degradation after retrieval to the ER or delivery to the lysosome/vacuole. Here, we discuss how these guardian pathways function, how their activities intersect upon induction of the UPR, and how decisions are made to dispose of misfolded proteins in the secretory pathway.
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Affiliation(s)
- Zhihao Sun
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA
| | - Jeffrey L Brodsky
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA
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120
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Mechanistic Connections between Endoplasmic Reticulum (ER) Redox Control and Mitochondrial Metabolism. Cells 2019; 8:cells8091071. [PMID: 31547228 PMCID: PMC6769559 DOI: 10.3390/cells8091071] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 09/06/2019] [Accepted: 09/07/2019] [Indexed: 12/21/2022] Open
Abstract
The past decade has seen the emergence of endoplasmic reticulum (ER) chaperones as key determinants of contact formation between mitochondria and the ER on the mitochondria-associated membrane (MAM). Despite the known roles of ER–mitochondria tethering factors like PACS-2 and mitofusin-2, it is not yet entirely clear how they mechanistically interact with the ER environment to determine mitochondrial metabolism. In this article, we review the mechanisms used to communicate ER redox and folding conditions to the mitochondria, presumably with the goal of controlling mitochondrial metabolism at the Krebs cycle and at the electron transport chain, leading to oxidative phosphorylation (OXPHOS). To achieve this goal, redox nanodomains in the ER and the interorganellar cleft influence the activities of ER chaperones and Ca2+-handling proteins to signal to mitochondria. This mechanism, based on ER chaperones like calnexin and ER oxidoreductases like Ero1α, controls reactive oxygen production within the ER, which can chemically modify the proteins controlling ER–mitochondria tethering, or mitochondrial membrane dynamics. It can also lead to the expression of apoptotic or metabolic transcription factors. The link between mitochondrial metabolism and ER homeostasis is evident from the specific functions of mitochondria–ER contact site (MERC)-localized Ire1 and PERK. These functions allow these two transmembrane proteins to act as mitochondria-preserving guardians, a function that is apparently unrelated to their functions in the unfolded protein response (UPR). In scenarios where ER stress cannot be resolved via the activation of mitochondrial OXPHOS, MAM-localized autophagosome formation acts to remove defective portions of the ER. ER chaperones such as calnexin are again critical regulators of this MERC readout.
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121
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CAND1 regulates lunapark for the proper tubular network of the endoplasmic reticulum. Sci Rep 2019; 9:13152. [PMID: 31511573 PMCID: PMC6739345 DOI: 10.1038/s41598-019-49542-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 08/27/2019] [Indexed: 12/31/2022] Open
Abstract
Endoplasmic reticulum (ER) tubules connect each other by three-way junctions, resulting in a tubular ER network. Oligomerization of three-way junction protein lunapark (Lnp) is important for its localization and the three-way junction stability. On the other hand, Lnp has an N-terminal ubiquitin ligase activity domain, which is also important for the three-way junction localization. To understand the mode of action of Lnp, we isolated Cullin-associated and neddylation-dissociated 1 (CAND1), a regulator of Skp1-Cul1-F-box (SCF) ubiquitin ligase, as a Lnp-binding protein by affinity chromatography. CAND1 and Lnp form a higher-molecular-weight complex in vitro, while they do not co-localize at the three-way junctions. CAND1 reduces the auto-ubiquitination activity of Lnp. CAND1 knockdown enhances proteasomal degradation of Lnp and reduces the tubular ER network in mammalian cells. These results suggest that CAND1 has the potency to promote the formation of the higher-molecular-weight complex with Lnp and reduce the auto-ubiquitination activity of Lnp, thereby regulating the three-way junction stability of the tubular ER network.
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122
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Irena R, Leszek K. The living organism: evolutionary design or an accident. BIO-ALGORITHMS AND MED-SYSTEMS 2019. [DOI: 10.1515/bams-2019-0035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
AbstractThe presented work discusses some evolutionary phenomena underlining the complexity of organism creation and surprisingly the short evolutionary time of this process in particular. Uncommonness of this process ensued from the necessary simultaneous combining of highly complicated biological mechanisms, of which some were generated independently before the direct evolutionary demand. This in conclusion points to still not fully understood biological program ensuring superiority of the permanent evolutionary progress over effects of purely random mutational changes as the driving mechanism in evolution.
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Affiliation(s)
- Roterman Irena
- Department of Bioinformatics and Telemedicine, Jagiellonian University – Medical College, Lazarza 16, 31-530 Krakow, Poland
| | - Konieczny Leszek
- Chair of Medical Biochemistry, Jagiellonian University, Medical College, Kopernika 7C, 31-034 Krakow, Poland
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123
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De Leonibus C, Cinque L, Settembre C. Emerging lysosomal pathways for quality control at the endoplasmic reticulum. FEBS Lett 2019; 593:2319-2329. [PMID: 31388984 DOI: 10.1002/1873-3468.13571] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 07/30/2019] [Accepted: 08/02/2019] [Indexed: 01/01/2023]
Abstract
Protein misfolding occurring in the endoplasmic reticulum (ER) might eventually lead to aggregation and cellular distress, and is a primary pathogenic mechanism in multiple human disorders. Mammals have developed evolutionary-conserved quality control mechanisms at the level of the ER. The best characterized is the ER-associated degradation (ERAD) pathway, through which misfolded proteins translocate from the ER to the cytosol and are subsequently proteasomally degraded. However, increasing evidence indicates that additional quality control mechanisms apply for misfolded ER clients that are not eligible for ERAD. This review focuses on the alternative, ERAD-independent, mechanisms of clearance of misfolded polypeptides from the ER. These processes, collectively referred to as ER-to-lysosome-associated degradation, involve ER-phagy, microautophagy or vesicular transport. The identification of the underlying molecular mechanisms is particularly important for developing new therapeutic approaches for human diseases associated with protein aggregate formation.
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Affiliation(s)
| | - Laura Cinque
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy
| | - Carmine Settembre
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy.,Department of Medical and Translational Science, University of Naples "Federico II", Italy
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124
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Delorme-Axford E, Popelka H, Klionsky DJ. TEX264 is a major receptor for mammalian reticulophagy. Autophagy 2019; 15:1677-1681. [PMID: 31362563 DOI: 10.1080/15548627.2019.1646540] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The endoplasmic reticulum (ER) is the main site of cellular protein and calcium homeostasis, as well as lipid synthesis in eukaryotic cells. Reticulophagy is the selective clearance and degradation of ER components and membranes by the cellular autophagy machinery. Recently, 2 groups (the laboratories of Noboru Mizushima and Wade Harper) independently identified the previously uncharacterized protein TEX264 (testis expressed gene 264) as a major receptor for selective reticulophagy in mammalian cells. Here we highlight and integrate the major findings of their recent work. Abbreviations: AIM: Atg8-interacting motif; AP-MS: affinity purification-mass spectrometry; ATL3: atlastin GTPase 3; Baf A1: bafilomycin A1; CCPG1: cell cycle progression 1; CRISPR: clustered regularly interspaced short palindromic repeats; GABARAP: gamma-aminobutyric acid receptor associated protein; GFP: green fluorescent protein; GyrI: gyrase inhibitor; IDR: intrinsically disordered region; IP: immunoprecipitation; KO: knockout; LIR: LC3-interacting region; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MEF: mouse embryonic fibroblast; MS: mass spectrometry; MTOR: mechanistic target of rapamycin kinase; RB1CC1/FIP200: RB1-inducible coiled-coil 1; RFP: red fluorescent protein; RNAi: RNA interference; RTN3: reticulon 3; RTN3L: long isoform of RTN3; siRNA: small interfering RNA; SARS: selective autophagy receptors; ss: signal sequence; TEM: transmission electron microscopy, TEX264: testis expressed gene 264; TMT: tandem mass tagging.
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Affiliation(s)
| | - Hana Popelka
- Life Sciences Institute, University of Michigan , Ann Arbor , MI , USA
| | - Daniel J Klionsky
- Life Sciences Institute, University of Michigan , Ann Arbor , MI , USA
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