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Date SS, Xu P, Hepowit NL, Diab NS, Best J, Xie B, Du J, Strieter ER, Jackson LP, MacGurn JA, Graham TR. Ubiquitination drives COPI priming and Golgi SNARE localization. eLife 2022; 11:e80911. [PMID: 35904239 PMCID: PMC9374436 DOI: 10.7554/elife.80911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 07/01/2022] [Indexed: 11/15/2022] Open
Abstract
Deciphering mechanisms controlling SNARE localization within the Golgi complex is crucial to understanding protein trafficking patterns within the secretory pathway. SNAREs are also thought to prime coatomer protein I (COPI) assembly to ensure incorporation of these essential cargoes into vesicles, but the regulation of these events is poorly understood. Here, we report roles for ubiquitin recognition by COPI in SNARE trafficking and in stabilizing interactions between Arf, COPI, and Golgi SNAREs in Saccharomyces cerevisiae. The ability of COPI to bind ubiquitin, but not the dilysine motif, through its N-terminal WD repeat domain of β'-COP or through an unrelated ubiquitin-binding domain is essential for the proper localization of Golgi SNAREs Bet1 and Gos1. We find that COPI, the ArfGAP Glo3, and multiple Golgi SNAREs are ubiquitinated. Notably, the binding of Arf and COPI to Gos1 is markedly enhanced by ubiquitination of these components. Glo3 is proposed to prime COPI-SNARE interactions; however, Glo3 is not enriched in the ubiquitin-stabilized SNARE-Arf-COPI complex but is instead enriched with COPI complexes that lack SNAREs. These results support a new model for how posttranslational modifications drive COPI priming events crucial for Golgi SNARE localization.
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Affiliation(s)
- Swapneeta S Date
- Department of Biological Sciences, Vanderbilt UniversityNashvilleUnited States
| | - Peng Xu
- Department of Biological Sciences, Vanderbilt UniversityNashvilleUnited States
| | - Nathaniel L Hepowit
- Department of Cell and Developmental Biology, Vanderbilt UniversityNashvilleUnited States
| | - Nicholas S Diab
- Department of Biological Sciences, Vanderbilt UniversityNashvilleUnited States
| | - Jordan Best
- Department of Biological Sciences, Vanderbilt UniversityNashvilleUnited States
| | - Boyang Xie
- Department of Biological Sciences, Vanderbilt UniversityNashvilleUnited States
| | - Jiale Du
- Department of Chemistry, University of Massachusetts AmherstAmherstUnited States
| | - Eric R Strieter
- Department of Chemistry, University of Massachusetts AmherstAmherstUnited States
| | - Lauren P Jackson
- Department of Biological Sciences, Vanderbilt UniversityNashvilleUnited States
| | - Jason A MacGurn
- Department of Cell and Developmental Biology, Vanderbilt UniversityNashvilleUnited States
| | - Todd R Graham
- Department of Biological Sciences, Vanderbilt UniversityNashvilleUnited States
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2
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Velázquez-Enríquez JM, Ramírez-Hernández AA, Navarro LMS, Reyes-Avendaño I, González-García K, Jiménez-Martínez C, Castro-Sánchez L, Sánchez-Chino XM, Vásquez-Garzón VR, Baltiérrez-Hoyos R. Proteomic Analysis Reveals Differential Expression Profiles in Idiopathic Pulmonary Fibrosis Cell Lines. Int J Mol Sci 2022; 23:ijms23095032. [PMID: 35563422 PMCID: PMC9105114 DOI: 10.3390/ijms23095032] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/18/2022] [Accepted: 04/28/2022] [Indexed: 02/04/2023] Open
Abstract
Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, irreversible lung disorder of unknown cause. This disease is characterized by profibrotic activation of resident pulmonary fibroblasts resulting in aberrant deposition of extracellular matrix (ECM) proteins. However, although much is known about the pathophysiology of IPF, the cellular and molecular processes that occur and allow aberrant fibroblast activation remain an unmet need. To explore the differentially expressed proteins (DEPs) associated with aberrant activation of these fibroblasts, we used the IPF lung fibroblast cell lines LL97A (IPF-1) and LL29 (IPF-2), compared to the normal lung fibroblast cell line CCD19Lu (NL-1). Protein samples were quantified and identified using a label-free quantitative proteomic analysis approach by liquid chromatography-tandem mass spectrometry (LC-MS/MS). DEPs were identified after pairwise comparison, including all experimental groups. Gene Ontology (GO) enrichment analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG), and Protein–Protein Interaction (PPI) network construction were used to interpret the proteomic data. Eighty proteins expressed exclusively in the IPF-1 and IPF-2 clusters were identified. In addition, 19 proteins were identified up-regulated in IPF-1 and 10 in IPF-2; 10 proteins were down-regulated in IPF-1 and 2 in IPF-2 when compared to the NL-1 proteome. Using the search tool for retrieval of interacting genes/proteins (STRING) software, a PPI network was constructed between the DEPs and the 80 proteins expressed exclusively in the IPF-2 and IPF-1 clusters, containing 115 nodes and 136 edges. The 10 hub proteins present in the IPP network were identified using the CytoHubba plugin of the Cytoscape software. GO and KEGG pathway analyses showed that the hub proteins were mainly related to cell adhesion, integrin binding, and hematopoietic cell lineage. Our results provide relevant information on DEPs present in IPF lung fibroblast cell lines when compared to the normal lung fibroblast cell line that could play a key role during IPF pathogenesis.
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Affiliation(s)
- Juan Manuel Velázquez-Enríquez
- Laboratorio de Fibrosis y Cáncer, Facultad de Medicina y Cirugía, Universidad Autónoma “Benito Juárez” de Oaxaca, Oaxaca 68120, Mexico; (J.M.V.-E.); (A.A.R.-H.); (I.R.-A.); (K.G.-G.)
| | - Alma Aurora Ramírez-Hernández
- Laboratorio de Fibrosis y Cáncer, Facultad de Medicina y Cirugía, Universidad Autónoma “Benito Juárez” de Oaxaca, Oaxaca 68120, Mexico; (J.M.V.-E.); (A.A.R.-H.); (I.R.-A.); (K.G.-G.)
| | | | - Itayetzi Reyes-Avendaño
- Laboratorio de Fibrosis y Cáncer, Facultad de Medicina y Cirugía, Universidad Autónoma “Benito Juárez” de Oaxaca, Oaxaca 68120, Mexico; (J.M.V.-E.); (A.A.R.-H.); (I.R.-A.); (K.G.-G.)
| | - Karina González-García
- Laboratorio de Fibrosis y Cáncer, Facultad de Medicina y Cirugía, Universidad Autónoma “Benito Juárez” de Oaxaca, Oaxaca 68120, Mexico; (J.M.V.-E.); (A.A.R.-H.); (I.R.-A.); (K.G.-G.)
| | - Cristian Jiménez-Martínez
- Departamento de Ingeniería Bioquímica, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Unidad Profesional Adolfo López Mateos, Zacatenco, Av. Wilfrido Massieu Esq. Cda. Miguel Stampa S/N, Alcaldía Gustavo A. Madero, Mexico City 07738, Mexico;
| | - Luis Castro-Sánchez
- Conacyt-Centro Universitario de Investigaciones Biomédicas “CUIB”, Universidad de Colima, Colima 28045, Mexico;
| | - Xariss Miryam Sánchez-Chino
- Catedra-Conacyt, Departamento de Salud El Colegio de La Frontera Sur, Unidad Villahermosa, Tabasco 86280, Mexico;
| | | | - Rafael Baltiérrez-Hoyos
- Conacyt-Facultad de Medicina y Cirugía, Universidad Autónoma “Benito Juárez” de Oaxaca, Oaxaca 68120, Mexico;
- Correspondence:
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3
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Watanabe A, Hataida H, Inoue N, Kamon K, Baba K, Sasaki K, Kimura R, Sasaki H, Eura Y, Ni WF, Shibasaki Y, Waguri S, Kokame K, Shiba Y. Arf GTPase-activating proteins SMAP1 and AGFG2 regulate the size of Weibel-Palade bodies and exocytosis of von Willebrand factor. Biol Open 2021; 10:271213. [PMID: 34369554 PMCID: PMC8430232 DOI: 10.1242/bio.058789] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 07/28/2021] [Indexed: 01/22/2023] Open
Abstract
Arf GTPase-Activating proteins (ArfGAPs) mediate the hydrolysis of GTP bound to ADP-ribosylation factors (Arfs), which are critical to form transport intermediates. ArfGAPs have been thought to be negative regulators of Arfs; however, accumulating evidence indicates that ArfGAPs are important for cargo sorting and promote membrane traffic. Weibel-Palade bodies (WPBs) are cigar-shaped secretory granules in endothelial cells that contain von Willebrand factor (vWF) as their main cargo. WPB biogenesis at the Golgi was reported to be regulated by Arf and their regulators, but the role of ArfGAPs has been unknown. In this study, we performed siRNA screening of ArfGAPs to investigate the role of ArfGAPs in the biogenesis of WPBs. We found two ArfGAPs, SMAP1 and AGFG2, to be involved in WPB size and vWF exocytosis, respectively. SMAP1 depletion resulted in small-sized WPBs, and the lysosomal inhibitor leupeptin recovered the size of WPBs. The results indicate that SMAP1 functions in preventing the degradation of cigar-shaped WPBs. On the other hand, AGFG2 downregulation resulted in the inhibition of vWF secretion upon Phorbol 12-myristate 13-acetate (PMA) or histamine stimulation, suggesting that AGFG2 plays a role in vWF exocytosis. Our study revealed unexpected roles of ArfGAPs in vWF transport. Summary: The Arf GTPase-activating proteins SMAP1 and AGFG2 regulate the size of Weibel-Palade bodies and exocytosis of von Willebrand factor.
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Affiliation(s)
- Asano Watanabe
- Faculty of Science and Engineering, Iwate University, Morioka, 020-8551, Japan
| | - Hikari Hataida
- Faculty of Science and Engineering, Iwate University, Morioka, 020-8551, Japan
| | - Naoya Inoue
- Faculty of Science and Engineering, Iwate University, Morioka, 020-8551, Japan
| | - Kosuke Kamon
- Faculty of Science and Engineering, Iwate University, Morioka, 020-8551, Japan
| | - Keigo Baba
- Faculty of Science and Engineering, Iwate University, Morioka, 020-8551, Japan
| | - Kuniaki Sasaki
- Faculty of Science and Engineering, Iwate University, Morioka, 020-8551, Japan
| | - Rika Kimura
- Faculty of Science and Engineering, Iwate University, Morioka, 020-8551, Japan
| | - Honoka Sasaki
- Faculty of Science and Engineering, Iwate University, Morioka, 020-8551, Japan
| | - Yuka Eura
- Department of Molecular Pathogenesis, National Cerebral and Cardiovascular Center, Osaka, 564-8565, Japan
| | - Wei-Fen Ni
- Department of Biotechnology, National Kaohsiung Normal University, Kaohsiung, 80201, Taiwan
| | - Yuji Shibasaki
- Faculty of Science and Engineering, Iwate University, Morioka, 020-8551, Japan
| | - Satoshi Waguri
- Department of Anatomy and Histology, Fukushima Medical University, Fukushima, 960-1295, Japan
| | - Koichi Kokame
- Department of Molecular Pathogenesis, National Cerebral and Cardiovascular Center, Osaka, 564-8565, Japan
| | - Yoko Shiba
- Faculty of Science and Engineering, Iwate University, Morioka, 020-8551, Japan
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Li Y, Jian X, Yin P, Zhu G, Zhang L. Elucidating the Host Interactome of EV-A71 2C Reveals Viral Dependency Factors. Front Microbiol 2019; 10:636. [PMID: 31001221 PMCID: PMC6454016 DOI: 10.3389/fmicb.2019.00636] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 03/13/2019] [Indexed: 01/21/2023] Open
Abstract
Viral protein 2C plays a critical role in EV-A71 replication. The discovery of 2C binding proteins will likely provide potential targets to treat EV-A71 infection. Here, we provide a global proteomic analysis of the human proteins that interact with the EV-A71 2C protein. TRIM4, exportin2, and ARFGAP1 were validated as 2C binding partners. Further functional studies revealed that TRIM4, exportin2, and ARFGAP1 were novel host dependency factors for EV-A71. Moreover, enteroviruses’ 2C family proteins interacted with exportin2 and ARFGAP1. In conclusion, our study provides a cellular interactome of the EV-A71 2C and identifies the proviral roles of TRIM4, exportin2, and ARFGAP1 in EV-A71 infection.
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Affiliation(s)
- Ye Li
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Xia Jian
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Peiqi Yin
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Guofeng Zhu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, and Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Leiliang Zhang
- Institute of Basic Medicine, Shandong Academy of Medical Sciences, Jinan, China
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5
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Del Bel LM, Brill JA. Sac1, a lipid phosphatase at the interface of vesicular and nonvesicular transport. Traffic 2018; 19:301-318. [PMID: 29411923 DOI: 10.1111/tra.12554] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 02/02/2018] [Accepted: 02/02/2018] [Indexed: 12/14/2022]
Abstract
The lipid phosphatase Sac1 dephosphorylates phosphatidylinositol 4-phosphate (PI4P), thereby holding levels of this crucial membrane signaling molecule in check. Sac1 regulates multiple cellular processes, including cytoskeletal organization, membrane trafficking and cell signaling. Here, we review the structure and regulation of Sac1, its roles in cell signaling and development and its links to health and disease. Remarkably, many of the diverse roles attributed to Sac1 can be explained by the recent discovery of its requirement at membrane contact sites, where its consumption of PI4P is proposed to drive interorganelle transfer of other cellular lipids, thereby promoting normal lipid homeostasis within cells.
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Affiliation(s)
- Lauren M Del Bel
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Julie A Brill
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
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6
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Kon S, Funaki T, Satake M. Putative terminator and/or effector functions of Arf GAPs in the trafficking of clathrin-coated vesicles. CELLULAR LOGISTICS 2014; 1:86-89. [PMID: 21922072 DOI: 10.4161/cl.1.3.16192] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Revised: 06/05/2011] [Accepted: 06/06/2011] [Indexed: 11/19/2022]
Abstract
The role of ArfGAP1 as a terminator or effector in COPi-vesicle formation has been the subject of ongoing discussions. Here, the discussion on the putative terminator/effector functions has been enlarged to include Arf GAP members involved in the formation of clathrin-coated vesicles. ACAP1, whose role has been studied extensively, enhances the recycling of endocytosed proteins to the plasma membrane. Importantly, this positive role appears to be an overall reflection of both the terminator and effector activities attributed to ACAP1. Other Arf GAP subtypes have also been suggested to possess both terminator and effector activities. Interestingly, while most Arf GAP proteins regulate membrane trafficking by acting as facilitators, a few Arf GAP subtypes act as inhibitors.
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Affiliation(s)
- Shunsuke Kon
- Institute of Development, Aging and Cancer; Tohoku University; Sendai, Japan
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7
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The Arf GTPase-activating protein SMAP1 promotes transferrin receptor endocytosis and interacts with SMAP2. Biochem Biophys Res Commun 2014; 453:473-9. [DOI: 10.1016/j.bbrc.2014.09.108] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2014] [Accepted: 09/24/2014] [Indexed: 12/18/2022]
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8
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Hepatitis C virus NS5A hijacks ARFGAP1 to maintain a phosphatidylinositol 4-phosphate-enriched microenvironment. J Virol 2014; 88:5956-66. [PMID: 24623438 DOI: 10.1128/jvi.03738-13] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
UNLABELLED Phosphatidylinositol 4-phosphate (PI4P) is well known to be upregulated during hepatitis C virus (HCV) replication. The role of PI4 kinases in HCV has been extensively investigated. Whether the PI4P phosphatase Sac1 is altered by HCV remains unclear. Here, we identified ARFGAP1 to be a novel host factor for HCV replication. We further show that Sac1 interacts with ARFGAP1 and inhibits HCV replication. The elevation of PI4P induced by HCV NS5A is abrogated when the coatomer protein I (COPI) pathway is inhibited. We also found an interaction between NS5A and ARFGAP1. Furthermore, we identified a conserved cluster of positively charged amino acids in NS5A critical for interaction between NS5A and ARFGAP1, induction of PI4P, and HCV replication. Our data demonstrate that ARFGAP1 is a host factor for HCV RNA replication. ARFGAP1 is hijacked by HCV NS5A to remove COPI cargo Sac1 from the site of HCV replication to maintain high levels of PI4P. Our findings provide an additional mechanism by which HCV enhances formation of a PI4P-rich environment. IMPORTANCE PI4P is enriched in the replication area of HCV; however, whether PI4P phosphatase Sac1 is subverted by HCV is not established. The detailed mechanism of how COPI contributes to viral replication remains unknown, though COPI components were hijacked by HCV. We demonstrate that ARFGAP1 is hijacked by HCV NS5A to remove COPI cargo Sac1 from the HCV replication area to maintain high-level PI4P generated by NS5A. Furthermore, we identify a conserved cluster of positively charged amino acids in NS5A, which are critical for interaction between NS5A and ARFGAP1, induction of PI4P, and HCV replication. This study will shed mechanistic insight on how other RNA viruses hijack COPI and Sac1.
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Schlacht A, Mowbrey K, Elias M, Kahn RA, Dacks JB. Ancient complexity, opisthokont plasticity, and discovery of the 11th subfamily of Arf GAP proteins. Traffic 2013; 14:636-49. [PMID: 23433073 DOI: 10.1111/tra.12063] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 02/20/2013] [Accepted: 02/22/2013] [Indexed: 12/14/2022]
Abstract
The organelle paralogy hypothesis is one model for the acquisition of nonendosymbiotic organelles, generated from molecular evolutionary analyses of proteins encoding specificity in the membrane traffic system. GTPase activating proteins (GAPs) for the ADP-ribosylation factor (Arfs) GTPases are additional regulators of the kinetics and fidelity of membrane traffic. Here we describe molecular evolutionary analyses of the Arf GAP protein family. Of the 10 subfamilies previously defined in humans, we find that 5 were likely present in the last eukaryotic common ancestor. Of the 3 most recently derived subfamilies, 1 was likely present in the ancestor of opisthokonts (animals and fungi) and apusomonads (flagellates classified as the sister lineage to opisthokonts), while 2 arose in the holozoan lineage. We also propose to have identified a novel ancient subfamily (ArfGAPC2), present in diverse eukaryotes but which is lost frequently, including in the opisthokonts. Surprisingly few ancient domains accompanying the ArfGAP domain were identified, in marked contrast to the extensively decorated human Arf GAPs. Phylogenetic analyses of the subfamilies reveal patterns of single and multiple gene duplications specific to the Holozoa, to some degree mirroring evolution of Arf GAP targets, the Arfs. Conservation, and lack thereof, of various residues in the ArfGAP structure provide contextualization of previously identified functional amino acids and their application to Arf GAP biology in general. Overall, our results yield insights into current Arf GAP biology, reveal complexity in the ancient eukaryotic ancestor and integrate the Arf GAP family into a proposed mechanism for the evolution of nonendosymbiotic organelles.
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Affiliation(s)
- Alexander Schlacht
- Faculty of Medicine and Dentistry, Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada
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10
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Shiba Y, Randazzo PA. ArfGAP1 function in COPI mediated membrane traffic: currently debated models and comparison to other coat-binding ArfGAPs. Histol Histopathol 2012; 27:1143-53. [PMID: 22806901 DOI: 10.14670/hh-27.1143] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The ArfGAPs are a family of proteins containing an ArfGAP catalytic domain that induces the hydrolysis of GTP bound to the small guanine nucleotide binding-protein ADP-ribosylation factor (Arf). Functional models for Arfs, which are regulators of membrane traffic, are based on the idea that guanine nucleotide-binding proteins function as switches: Arf with GTP bound is active and binds to effector proteins; the conversion of GTP to GDP inactivates Arf. The cellular activities of ArfGAPs have been examined primarily as regulatory proteins that inactivate Arf; however, Arf function in membrane traffic does not strictly adhere to the concept of a simple switch, adding complexity to models explaining the role of ArfGAPs. Here, we review the literature addressing the function Arf and ArfGAP1 in COPI mediated transport, focusing on two critical and integrated functions of membrane traffic, cargo sorting and vesicle coat polymerization. We briefly discuss other ArfGAPs that may have similar function in Arf-dependent membrane traffic outside the ER-Golgi.
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Affiliation(s)
- Yoko Shiba
- National Cancer Institute, Laboratory of Cellular and Molecular Biology, Bethesda, MD 20892, USA
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11
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Shiba Y, Luo R, Hinshaw JE, Szul T, Hayashi R, Sztul E, Nagashima K, Baxa U, Randazzo PA. ArfGAP1 promotes COPI vesicle formation by facilitating coatomer polymerization. CELLULAR LOGISTICS 2011; 1:139-154. [PMID: 22279613 PMCID: PMC3265926 DOI: 10.4161/cl.1.4.18896] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 11/21/2011] [Accepted: 11/29/2011] [Indexed: 12/31/2022]
Abstract
The role of ArfGAP1 in COPI vesicle biogenesis has been controversial. In work using isolated Golgi membranes, ArfGAP1 was found to promote COPI vesicle formation. In contrast, in studies using large unilamellar vesicles (LUVs) as model membranes, ArfGAP1 functioned as an uncoating factor inhibiting COPI vesicle formation. We set out to discriminate between these models. First, we reexamined the effect of ArfGAP1 on LUVs. We found that ArfGAP1 increased the efficiency of coatomer-induced deformation of LUVs. Second, ArfGAP1 and peptides from cargo facilitated self-assembly of coatomer into spherical structures in the absence of membranes, reminiscent of clathrin self-assembly. Third, in vivo, ArfGAP1 overexpression induced the accumulation of vesicles and allowed normal trafficking of a COPI cargo. Taken together, these data support the model in which ArfGAP1 promotes COPI vesicle formation and membrane traffic and identify a function for ArfGAP1 in the assembly of coatomer into COPI.
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Affiliation(s)
- Yoko Shiba
- Laboratory of Cellular and Molecular Biology; National Cancer Institute, Bethesda, MD USA
| | - Ruibai Luo
- Laboratory of Cellular and Molecular Biology; National Cancer Institute, Bethesda, MD USA
| | - Jenny E Hinshaw
- National Institute of Diabetes and Digestive and Kidney Disease; National Institutes of Health; Bethesda, MD USA
| | - Tomasz Szul
- Department of Cell Biology; The University of Alabama at Birmingham; Birmingham, AL USA
| | - Ryo Hayashi
- Laboratory of Cell Biology; National Cancer Institute; Bethesda, MD USA
| | - Elizabeth Sztul
- Department of Cell Biology; The University of Alabama at Birmingham; Birmingham, AL USA
| | - Kunio Nagashima
- Electron Microscopy Laboratory, ATP, SAIC-Frederick, Center for Cancer Research, National Cancer Institute; Frederick, MD USA
| | - Ulrich Baxa
- Electron Microscopy Laboratory, ATP, SAIC-Frederick, Center for Cancer Research, National Cancer Institute; Frederick, MD USA
| | - Paul A Randazzo
- Laboratory of Cellular and Molecular Biology; National Cancer Institute, Bethesda, MD USA
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