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Jacquemyn J, Kuenen S, Swerts J, Pavie B, Vijayan V, Kilic A, Chabot D, Wang YC, Schoovaerts N, Corthout N, Verstreken P. Parkinsonism mutations in DNAJC6 cause lipid defects and neurodegeneration that are rescued by Synj1. NPJ Parkinsons Dis 2023; 9:19. [PMID: 36739293 PMCID: PMC9899244 DOI: 10.1038/s41531-023-00459-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 01/16/2023] [Indexed: 02/06/2023] Open
Abstract
Recent evidence links dysfunctional lipid metabolism to the pathogenesis of Parkinson's disease, but the mechanisms are not resolved. Here, we generated a new Drosophila knock-in model of DNAJC6/Auxilin and find that the pathogenic mutation causes synaptic dysfunction, neurological defects and neurodegeneration, as well as specific lipid metabolism alterations. In these mutants, membrane lipids containing long-chain polyunsaturated fatty acids, including phosphatidylinositol lipid species that are key for synaptic vesicle recycling and organelle function, are reduced. Overexpression of another protein mutated in Parkinson's disease, Synaptojanin-1, known to bind and metabolize specific phosphoinositides, rescues the DNAJC6/Auxilin lipid alterations, the neuronal function defects and neurodegeneration. Our work reveals a functional relation between two proteins mutated in Parkinsonism and implicates deregulated phosphoinositide metabolism in the maintenance of neuronal integrity and neuronal survival.
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Affiliation(s)
- Julie Jacquemyn
- VIB-KU Leuven Center for Brain & Disease Research, 3000, Leuven, Belgium
- KU Leuven, Department of Neurosciences, Leuven Brain Institute, Mission Lucidity, 3000, Leuven, Belgium
- Neuroscience and Mental Health Institute, University of Alberta, Department of Physiology, Department of Cell Biology, Group on Molecular and Cell Biology of Lipids, Edmonton, Alberta, Canada
| | - Sabine Kuenen
- VIB-KU Leuven Center for Brain & Disease Research, 3000, Leuven, Belgium
- KU Leuven, Department of Neurosciences, Leuven Brain Institute, Mission Lucidity, 3000, Leuven, Belgium
| | - Jef Swerts
- VIB-KU Leuven Center for Brain & Disease Research, 3000, Leuven, Belgium
- KU Leuven, Department of Neurosciences, Leuven Brain Institute, Mission Lucidity, 3000, Leuven, Belgium
| | - Benjamin Pavie
- VIB-KU Leuven Center for Brain & Disease Research, 3000, Leuven, Belgium
- KU Leuven, Department of Neurosciences, Leuven Brain Institute, Mission Lucidity, 3000, Leuven, Belgium
- VIB-Bioimaging Core, 3000, Leuven, Belgium
| | - Vinoy Vijayan
- VIB-KU Leuven Center for Brain & Disease Research, 3000, Leuven, Belgium
- KU Leuven, Department of Neurosciences, Leuven Brain Institute, Mission Lucidity, 3000, Leuven, Belgium
| | - Ayse Kilic
- VIB-KU Leuven Center for Brain & Disease Research, 3000, Leuven, Belgium
- KU Leuven, Department of Neurosciences, Leuven Brain Institute, Mission Lucidity, 3000, Leuven, Belgium
| | - Dries Chabot
- VIB-KU Leuven Center for Brain & Disease Research, 3000, Leuven, Belgium
- KU Leuven, Department of Neurosciences, Leuven Brain Institute, Mission Lucidity, 3000, Leuven, Belgium
| | - Yu-Chun Wang
- VIB-KU Leuven Center for Brain & Disease Research, 3000, Leuven, Belgium
- KU Leuven, Department of Neurosciences, Leuven Brain Institute, Mission Lucidity, 3000, Leuven, Belgium
- VIB Technology Watch, Technology Innovation Laboratory, VIB, Gent, Belgium
| | - Nils Schoovaerts
- VIB-KU Leuven Center for Brain & Disease Research, 3000, Leuven, Belgium
- KU Leuven, Department of Neurosciences, Leuven Brain Institute, Mission Lucidity, 3000, Leuven, Belgium
| | - Nikky Corthout
- VIB-KU Leuven Center for Brain & Disease Research, 3000, Leuven, Belgium
- KU Leuven, Department of Neurosciences, Leuven Brain Institute, Mission Lucidity, 3000, Leuven, Belgium
- VIB-Bioimaging Core, 3000, Leuven, Belgium
| | - Patrik Verstreken
- VIB-KU Leuven Center for Brain & Disease Research, 3000, Leuven, Belgium.
- KU Leuven, Department of Neurosciences, Leuven Brain Institute, Mission Lucidity, 3000, Leuven, Belgium.
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Zhao H, Ren X, Kong R, Shi L, Li Z, Wang R, Ma R, Zhao H, Liu F, Chang HC, Chen CH, Li Z. Auxilin regulates intestinal stem cell proliferation through EGFR. Stem Cell Reports 2022; 17:1120-1137. [PMID: 35427486 PMCID: PMC9133653 DOI: 10.1016/j.stemcr.2022.03.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 03/14/2022] [Accepted: 03/15/2022] [Indexed: 12/11/2022] Open
Abstract
Adult tissue homeostasis is maintained by residential stem cells. The proliferation and differentiation of adult stem cells must be tightly balanced to avoid excessive proliferation or premature differentiation. However, how stem cell proliferation is properly controlled remains elusive. Here, we find that auxilin (Aux) restricts intestinal stem cell (ISC) proliferation mainly through EGFR signaling. aux depletion leads to excessive ISC proliferation and midgut homeostasis disruption, which is unlikely caused by defective Notch signaling. Aux is expressed in multiple types of intestinal cells. Interestingly, aux depletion causes a dramatic increase in EGFR signaling, with a strong accumulation of EGFR at the plasma membrane and an increased expression of EGFR ligands in response to tissue stress. Furthermore, Aux co-localizes and associates with EGFR. Finally, blocking EGFR signaling completely suppresses the defects caused by aux depletion. Together, these data demonstrate that Aux mainly safeguards EGFR activation to keep a proper ISC proliferation rate to maintain midgut homeostasis.
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Affiliation(s)
- Hang Zhao
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Xuejing Ren
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Ruiyan Kong
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Lin Shi
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Zhengran Li
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Runqi Wang
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Rui Ma
- Department of Neurology, Capital Medical University, Beijing 100053, China
| | - Huiqing Zhao
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Fuli Liu
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Henry C Chang
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Chun-Hong Chen
- Division of Molecular and Genomic Medicine, National Health Research Institute, 35, Keyan Road, Zhunan Town, Miaoli County 350, Taiwan
| | - Zhouhua Li
- College of Life Sciences, Capital Normal University, Beijing 100048, China.
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Liu M, Hu J, Zhang A, Dai Y, Chen W, He Y, Zhang H, Zheng X, Zhang Z. Auxilin-like protein MoSwa2 promotes effector secretion and virulence as a clathrin uncoating factor in the rice blast fungus Magnaporthe oryzae. THE NEW PHYTOLOGIST 2021; 230:720-736. [PMID: 33423301 PMCID: PMC8048681 DOI: 10.1111/nph.17181] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 01/04/2021] [Indexed: 05/03/2023]
Abstract
Plant pathogens exploit the extracellular matrix (ECM) to inhibit host immunity during their interactions with the host. The formation of ECM involves a series of continuous steps of vesicular transport events. To understand how such vesicle trafficking impacts ECM and virulence in the rice blast fungus Magnaporthe oryzae, we characterised MoSwa2, a previously identified actin-regulating kinase MoArk1 interacting protein, as an orthologue of the auxilin-like clathrin uncoating factor Swa2 of the budding yeast Saccharomyces cerevisiae. We found that MoSwa2 functions as an uncoating factor of the coat protein complex II (COPII) via an interaction with the COPII subunit MoSec24-2. Loss of MoSwa2 led to a deficiency in the secretion of extracellular proteins, resulting in both restricted growth of invasive hyphae and reduced inhibition of host immunity. Additionally, extracellular fluid (ECF) proteome analysis revealed that MoSwa2-regulated extracellular proteins include many redox proteins such as the berberine bridge enzyme-like (BBE-like) protein MoSef1. We further found that MoSef1 functions as an apoplastic virulent factor that inhibits the host immune response. Our studies revealed a novel function of a COPII uncoating factor in vesicular transport that is critical in the suppression of host immunity and pathogenicity of M. oryzae.
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Affiliation(s)
- Muxing Liu
- Department of Plant PathologyCollege of Plant ProtectionNanjing Agricultural UniversityKey Laboratory of Integrated Management of Crop Diseases and PestsMinistry of EducationNanjing210095China
- The Key Laboratory of Plant ImmunityNanjing Agricultural UniversityNanjing210095China
| | - Jiexiong Hu
- Department of Plant PathologyCollege of Plant ProtectionNanjing Agricultural UniversityKey Laboratory of Integrated Management of Crop Diseases and PestsMinistry of EducationNanjing210095China
| | - Ao Zhang
- Department of Plant PathologyCollege of Plant ProtectionNanjing Agricultural UniversityKey Laboratory of Integrated Management of Crop Diseases and PestsMinistry of EducationNanjing210095China
| | - Ying Dai
- Department of Plant PathologyCollege of Plant ProtectionNanjing Agricultural UniversityKey Laboratory of Integrated Management of Crop Diseases and PestsMinistry of EducationNanjing210095China
| | - Weizhong Chen
- Department of Plant PathologyCollege of Plant ProtectionNanjing Agricultural UniversityKey Laboratory of Integrated Management of Crop Diseases and PestsMinistry of EducationNanjing210095China
| | - Yanglan He
- Department of Plant PathologyCollege of Plant ProtectionNanjing Agricultural UniversityKey Laboratory of Integrated Management of Crop Diseases and PestsMinistry of EducationNanjing210095China
| | - Haifeng Zhang
- Department of Plant PathologyCollege of Plant ProtectionNanjing Agricultural UniversityKey Laboratory of Integrated Management of Crop Diseases and PestsMinistry of EducationNanjing210095China
| | - Xiaobo Zheng
- Department of Plant PathologyCollege of Plant ProtectionNanjing Agricultural UniversityKey Laboratory of Integrated Management of Crop Diseases and PestsMinistry of EducationNanjing210095China
| | - Zhengguang Zhang
- Department of Plant PathologyCollege of Plant ProtectionNanjing Agricultural UniversityKey Laboratory of Integrated Management of Crop Diseases and PestsMinistry of EducationNanjing210095China
- The Key Laboratory of Plant ImmunityNanjing Agricultural UniversityNanjing210095China
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Segarra VA, Sharma A, Lemmon SK. Atg27p localization is clathrin- and Ent3p/5p-dependent. MICROPUBLICATION BIOLOGY 2021; 2021. [PMID: 33817565 PMCID: PMC8008256 DOI: 10.17912/micropub.biology.000381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The autophagy-related protein Atg27p has been previously shown to localize to the autophagy-specific pre-autophagosomal structure (PAS) as well as to several organelles, including the late Golgi, the vacuolar membrane, and the endosome. Given that Atg27p localization to the vacuolar membrane in particular has been shown to be dependent on both its C-terminal tyrosine sorting motif and the AP-3 adaptor, and that Atg27p can be found in clathrin-coated vesicles, we set out to determine whether Atg27p localization inside cells is dependent on clathrin or on any of its cargo adaptors. We report that Atg27p localization is clathrin- and Ent3p/5p-dependent.
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Affiliation(s)
| | - Anupam Sharma
- Department of Microbiology, University of Georgia, Athens, GA, USA 30602
| | - Sandra K Lemmon
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, USA 33101
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5
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Segarra VA, Sharma A, Lemmon SK. Atg27p co-fractionates with clathrin-coated vesicles in budding yeast. MICROPUBLICATION BIOLOGY 2021; 2021. [PMID: 33817564 PMCID: PMC8008255 DOI: 10.17912/micropub.biology.000380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Atg27p, a single-pass transmembrane protein that functions in autophagy, localizes to a variety of cellular compartments including the pre-autophagosomal structure, late Golgi, vacuolar membrane, as well as early and late endosomes. Its cytoplasmic C-terminus contains a tyrosine sorting motif that allows for its transport to the vacuolar membrane and an additional sequence that allows for its retrieval from the vacuolar membrane to the endosome. Since clathrin is well known to mediate vesicular transport in the endomembrane system, the trafficking of Atg27p and its tyrosine sorting motif suggested that it might be trafficked inside clathrin-coated vesicles (CCVs). In our previous studies, Atg27p was identified by mass spectrometry as a potential component in CCVs, as it was present in CCVs isolated from both WT and auxilin-depleted cells. We now confirm that Atg27p is a component of CCVs using immunoblotting and additional mass spectrometry data.
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Affiliation(s)
| | - Anupam Sharma
- Department of Microbiology, University of Georgia, Athens, GA, USA 30602
| | - Sandra K Lemmon
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, USA 33101
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Wang C, Scott SM, Sun S, Zhao P, Hutt DM, Shao H, Gestwicki JE, Balch WE. Individualized management of genetic diversity in Niemann-Pick C1 through modulation of the Hsp70 chaperone system. Hum Mol Genet 2020; 29:1-19. [PMID: 31509197 PMCID: PMC7001602 DOI: 10.1093/hmg/ddz215] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 08/05/2019] [Accepted: 09/02/2019] [Indexed: 12/21/2022] Open
Abstract
Genetic diversity provides a rich repository for understanding the role of proteostasis in the management of the protein fold in human biology. Failure in proteostasis can trigger multiple disease states, affecting both human health and lifespan. Niemann-Pick C1 (NPC1) disease is a rare genetic disorder triggered by mutations in NPC1, a multi-spanning transmembrane protein that is trafficked through the exocytic pathway to late endosomes (LE) and lysosomes (Ly) (LE/Ly) to globally manage cholesterol homeostasis. Defects triggered by >300 NPC1 variants found in the human population inhibit export of NPC1 protein from the endoplasmic reticulum (ER) and/or function in downstream LE/Ly, leading to cholesterol accumulation and onset of neurodegeneration in childhood. We now show that the allosteric inhibitor JG98, that targets the cytosolic Hsp70 chaperone/co-chaperone complex, can significantly improve the trafficking and post-ER protein level of diverse NPC1 variants. Using a new approach to model genetic diversity in human disease, referred to as variation spatial profiling, we show quantitatively how JG98 alters the Hsp70 chaperone/co-chaperone system to adjust the spatial covariance (SCV) tolerance and set-points on an amino acid residue-by-residue basis in NPC1 to differentially regulate variant trafficking, stability, and cholesterol homeostasis, results consistent with the role of BCL2-associated athanogene family co-chaperones in managing the folding status of NPC1 variants. We propose that targeting the cytosolic Hsp70 system by allosteric regulation of its chaperone/co-chaperone based client relationships can be used to adjust the SCV tolerance of proteostasis buffering capacity to provide an approach to mitigate systemic and neurological disease in the NPC1 population.
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Affiliation(s)
- Chao Wang
- Department of Molecular Medicine, Scripps Research, La Jolla, CA 92037, USA
| | - Samantha M Scott
- Department of Molecular Medicine, Scripps Research, La Jolla, CA 92037, USA
| | - Shuhong Sun
- Department of Molecular Medicine, Scripps Research, La Jolla, CA 92037, USA
| | - Pei Zhao
- Department of Molecular Medicine, Scripps Research, La Jolla, CA 92037, USA
| | - Darren M Hutt
- Department of Molecular Medicine, Scripps Research, La Jolla, CA 92037, USA
| | - Hao Shao
- Department of Pharmaceutical Chemistry, University of California at San Francisco, San Francisco, CA 94158, USA
| | - Jason E Gestwicki
- Department of Pharmaceutical Chemistry, University of California at San Francisco, San Francisco, CA 94158, USA
| | - William E Balch
- Department of Molecular Medicine, Scripps Research, La Jolla, CA 92037, USA
- The Skaggs Institute for Chemical Biology, Scripps Research, La Jolla, CA 92037, USA
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8
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Inoshita T, Cui C, Hattori N, Imai Y. Regulation of membrane dynamics by Parkinson's disease-associated genes. J Genet 2018; 97:715-725. [PMID: 30027905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Parkinson's disease (PD), the second most common neurodegenerative disease after Alzheimer's disease, develops sporadically, and its cause is unknown. However, 5-10% of PD cases are inherited as monogenic diseases, which provides a chance to understand the molecular mechanisms underlying neurodegeneration. Over 20 causative genes have already been identified and are being characterized. These PD-associated genes are broadly classified into two groups: genes involved in mitochondrial functions and genes related to membrane dynamics such as intracellular vesicle transport and the lysosomal pathway. In this review, we summarize the latest findings on the mechanism by which members of the latter group of PD-associated genes regulate membrane dynamics, and we discuss how mutations of these genes lead to dopaminergic neurodegeneration.
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Affiliation(s)
- Tsuyoshi Inoshita
- Department of Research for Parkinson's Disease, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan.
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Adamowski M, Narasimhan M, Kania U, Glanc M, De Jaeger G, Friml J. A Functional Study of AUXILIN-LIKE1 and 2, Two Putative Clathrin Uncoating Factors in Arabidopsis. THE PLANT CELL 2018; 30:700-716. [PMID: 29511054 PMCID: PMC5894831 DOI: 10.1105/tpc.17.00785] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 01/16/2018] [Accepted: 03/05/2018] [Indexed: 05/20/2023]
Abstract
Clathrin-mediated endocytosis (CME) is a cellular trafficking process in which cargoes and lipids are internalized from the plasma membrane into vesicles coated with clathrin and adaptor proteins. CME is essential for many developmental and physiological processes in plants, but its underlying mechanism is not well characterized compared with that in yeast and animal systems. Here, we searched for new factors involved in CME in Arabidopsis thaliana by performing tandem affinity purification of proteins that interact with clathrin light chain, a principal component of the clathrin coat. Among the confirmed interactors, we found two putative homologs of the clathrin-coat uncoating factor auxilin previously described in non-plant systems. Overexpression of AUXILIN-LIKE1 and AUXILIN-LIKE2 in Arabidopsis caused an arrest of seedling growth and development. This was concomitant with inhibited endocytosis due to blocking of clathrin recruitment after the initial step of adaptor protein binding to the plasma membrane. By contrast, auxilin-like1/2 loss-of-function lines did not present endocytosis-related developmental or cellular phenotypes under normal growth conditions. This work contributes to the ongoing characterization of the endocytotic machinery in plants and provides a robust tool for conditionally and specifically interfering with CME in Arabidopsis.
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Affiliation(s)
| | | | - Urszula Kania
- IST Austria, 3400 Klosterneuburg, Austria
- Ghent University, Department of Plant Biotechnology and Bioinformatics, 9052 Ghent, Belgium
- VIB Center for Plant Systems Biology, 9052 Ghent, Belgium
| | - Matouš Glanc
- IST Austria, 3400 Klosterneuburg, Austria
- Department of Experimental Plant Biology, Faculty of Science, Charles University, 12844 Prague, Czech Republic
| | - Geert De Jaeger
- Ghent University, Department of Plant Biotechnology and Bioinformatics, 9052 Ghent, Belgium
- VIB Center for Plant Systems Biology, 9052 Ghent, Belgium
| | - Jiří Friml
- IST Austria, 3400 Klosterneuburg, Austria
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10
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Geva Y, Crissman J, Arakel EC, Gómez-Navarro N, Chuartzman SG, Stahmer KR, Schwappach B, Miller EA, Schuldiner M. Two novel effectors of trafficking and maturation of the yeast plasma membrane H + -ATPase. Traffic 2017; 18:672-682. [PMID: 28727280 PMCID: PMC5607100 DOI: 10.1111/tra.12503] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 07/17/2017] [Accepted: 07/17/2017] [Indexed: 11/28/2022]
Abstract
The endoplasmic reticulum (ER) is the entry site of proteins into the endomembrane system. Proteins exit the ER via coat protein II (COPII) vesicles in a selective manner, mediated either by direct interaction with the COPII coat or aided by cargo receptors. Despite the fundamental role of such receptors in protein sorting, only a few have been identified. To further define the machinery that packages secretory cargo and targets proteins from the ER to Golgi membranes, we used multiple systematic approaches, which revealed 2 uncharacterized proteins that mediate the trafficking and maturation of Pma1, the essential yeast plasma membrane proton ATPase. Ydl121c (Exp1) is an ER protein that binds Pma1, is packaged into COPII vesicles, and whose deletion causes ER retention of Pma1. Ykl077w (Psg1) physically interacts with Exp1 and can be found in the Golgi and coat protein I (COPI) vesicles but does not directly bind Pma1. Loss of Psg1 causes enhanced degradation of Pma1 in the vacuole. Our findings suggest that Exp1 is a Pma1 cargo receptor and that Psg1 aids Pma1 maturation in the Golgi or affects its retrieval. More generally our work shows the utility of high content screens in the identification of novel trafficking components.
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Affiliation(s)
- Yosef Geva
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Jonathan Crissman
- Department of Biological Sciences, Columbia University, New York, NY
| | - Eric C Arakel
- Department of Molecular Biology, Universitätsmedizin Göttingen, Göttingen, Germany
| | | | - Silvia G Chuartzman
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Kyle R Stahmer
- Department of Biological Sciences, Columbia University, New York, NY
| | - Blanche Schwappach
- Department of Molecular Biology, Universitätsmedizin Göttingen, Göttingen, Germany
| | - Elizabeth A Miller
- Department of Biological Sciences, Columbia University, New York, NY.,MRC Laboratory of Molecular Biology, Cell Biology Division, Cambridge, UK
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
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Parashar S, Mukhopadhyay A. GTPase Sar1 regulates the trafficking and secretion of the virulence factor gp63 in Leishmania. J Biol Chem 2017; 292:12111-12125. [PMID: 28576830 DOI: 10.1074/jbc.m117.784033] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 05/30/2017] [Indexed: 12/30/2022] Open
Abstract
Metalloprotease gp63 (Leishmania donovani gp63 (Ldgp63)) is a critical virulence factor secreted by Leishmania However, how newly synthesized Ldgp63 exits the endoplasmic reticulum (ER) and is secreted by this parasite is unknown. Here, we cloned, expressed, and characterized the GTPase LdSar1 and other COPII components like LdSec23, LdSec24, LdSec13, and LdSec31 from Leishmania to understand their role in ER exit of Ldgp63. Using dominant-positive (LdSar1:H74L) and dominant-negative (LdSar1:T34N) mutants of LdSar1, we found that GTP-bound LdSar1 specifically binds to LdSec23, which binds, in turn, with LdSec24(1-702) to form a prebudding complex. Moreover, LdSec13 specifically interacted with His6-LdSec31(1-603), and LdSec31 bound the prebudding complex via LdSec23. Interestingly, dileucine 594/595 and valine 597 residues present in the Ldgp63 C-terminal domain were critical for binding with LdSec24(703-966), and GFP-Ldgp63L594A/L595A or GFP-Ldgp63V597S mutants failed to exit from the ER. Moreover, Ldgp63-containing COPII vesicle budding from the ER was inhibited by LdSar1:T34N in an in vitro budding assay, indicating that GTP-bound LdSar1 is required for budding of Ldgp63-containing COPII vesicles. To directly demonstrate the function of LdSar1 in Ldgp63 trafficking, we coexpressed RFP-Ldgp63 along with LdSar1:WT-GFP or LdSar1:T34N-GFP and found that LdSar1:T34N overexpression blocks Ldgp63 trafficking and secretion in Leishmania Finally, we noted significantly compromised survival of LdSar1:T34N-GFP-overexpressing transgenic parasites in macrophages. Taken together, these results indicated that Ldgp63 interacts with the COPII complex via LdSec24 for Ldgp63 ER exit and subsequent secretion.
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Affiliation(s)
- Smriti Parashar
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110067, India
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12
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Gorenberg EL, Chandra SS. The Role of Co-chaperones in Synaptic Proteostasis and Neurodegenerative Disease. Front Neurosci 2017; 11:248. [PMID: 28579939 PMCID: PMC5437171 DOI: 10.3389/fnins.2017.00248] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 04/18/2017] [Indexed: 12/14/2022] Open
Abstract
Synapses must be preserved throughout an organism's lifespan to allow for normal brain function and behavior. Synapse maintenance is challenging given the long distances between the termini and the cell body, reliance on axonal transport for delivery of newly synthesized presynaptic proteins, and high rates of synaptic vesicle exo- and endocytosis. Hence, synapses rely on efficient proteostasis mechanisms to preserve their structure and function. To this end, the synaptic compartment has specific chaperones to support its functions. Without proper synaptic chaperone activity, local proteostasis imbalances lead to neurotransmission deficits, dismantling of synapses, and neurodegeneration. In this review, we address the roles of four synaptic chaperones in the maintenance of the nerve terminal, as well as their genetic links to neurodegenerative disease. Three of these are Hsp40 co-chaperones (DNAJs): Cysteine String Protein alpha (CSPα; DNAJC5), auxilin (DNAJC6), and Receptor-Mediated Endocytosis 8 (RME-8; DNAJC13). These co-chaperones contain a conserved J domain through which they form a complex with heat shock cognate 70 (Hsc70), enhancing the chaperone's ATPase activity. CSPα is a synaptic vesicle protein known to chaperone the t-SNARE SNAP-25 and the endocytic GTPase dynamin-1, thereby regulating synaptic vesicle exocytosis and endocytosis. Auxilin binds assembled clathrin cages, and through its interactions with Hsc70 leads to the uncoating of clathrin-coated vesicles, a process necessary for the regeneration of synaptic vesicles. RME-8 is a co-chaperone on endosomes and may have a role in clathrin-coated vesicle endocytosis on this organelle. These three co-chaperones maintain client function by preserving folding and assembly to prevent client aggregation, but they do not break down aggregates that have already formed. The fourth synaptic chaperone we will discuss is Heat shock protein 110 (Hsp110), which interacts with Hsc70, DNAJAs, and DNAJBs to constitute a disaggregase. Hsp110-related disaggregase activity is present at the synapse and is known to protect against aggregation of proteins such as α-synuclein. Congruent with their importance in the nervous system, mutations of these co-chaperones lead to familial neurodegenerative disease. CSPα mutations cause adult neuronal ceroid lipofuscinosis, while auxilin mutations result in early-onset Parkinson's disease, demonstrating their significance in preservation of the nervous system.
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Affiliation(s)
- Erica L Gorenberg
- Interdepartmental Neuroscience Program, Yale UniversityNew Haven, CT, United States
| | - Sreeganga S Chandra
- Department of Neurology, Yale UniversityNew Haven, CT, United States.,Department of Neuroscience, Yale UniversityNew Haven, CT, United States
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