1
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Pocognoni CA, Nawara T, Bhatt JM, Lee E, Jian X, Randazzo P, Sztul E. The lipid flippase ATP8A1 regulates the recruitment of ARF effectors to the trans-Golgi Network. Arch Biochem Biophys 2024; 758:110049. [PMID: 38879142 DOI: 10.1016/j.abb.2024.110049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 05/18/2024] [Accepted: 06/05/2024] [Indexed: 06/30/2024]
Abstract
Formation of transport vesicles requires the coordinate activity of the coating machinery that selects cargo into the nascent vesicle and the membrane bending machinery that imparts curvature to the forming bud. Vesicle coating at the trans-Golgi Network (TGN) involves AP1, GGA2 and clathrin, which are recruited to membranes by activated ARF GTPases. The ARF activation at the TGN is mediated by the BIG1 and BIG2 guanine nucleotide exchange factors (GEFs). Membrane deformation at the TGN has been shown to be mediated by lipid flippases, including ATP8A1, that moves phospholipids from the inner to the outer leaflet of the TGN membrane. We probed a possible coupling between the coating and deformation machineries by testing for an interaction between BIG1, BIG2 and ATP8A1, and by assessing whether such an interaction may influence coating efficiency. Herein, we document that BIG1 and BIG2 co-localize with ATP8A1 in both, static and highly mobile TGN elements, and that BIG1 and BIG2 bind ATP8A1. We show that the interaction involves the catalytic Sec7 domain of the GEFs and the cytosolic C-terminal tail of ATP8A1. Moreover, we report that the expression of ATP8A1, but not ATP8A1 lacking the GEF-binding cytosolic tail, increases the generation of activated ARFs at the TGN and increases the selective recruitment of AP1, GGA2 and clathrin to TGN membranes. This occurs without increasing BIG1 or BIG2 levels at the TGN, suggesting that the binding of the ATP8A1 flippase tail to the Sec7 domain of BIG1/BIG2 increases their catalytic activity. Our results support a model in which a flippase component of the deformation machinery impacts the activity of the GEF component of the coating machinery.
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Affiliation(s)
- Cristian A Pocognoni
- Instituto de Histología y Embriología de Mendoza (IHEM), Universidad Nacional de Cuyo, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Mendoza 5500, Argentina.
| | - Tomasz Nawara
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 731, Birmingham, AL, 35233-2008, USA
| | - Jay M Bhatt
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 731, Birmingham, AL, 35233-2008, USA
| | - Eunjoo Lee
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 731, Birmingham, AL, 35233-2008, USA
| | - Xiaoying Jian
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, NHLBI, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Paul Randazzo
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, NHLBI, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Elizabeth Sztul
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 731, Birmingham, AL, 35233-2008, USA
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2
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B.R. R, Shah N, Joshi P, Madhusudan MS, Balasubramanian N. Kinetics of Arf1 inactivation regulates Golgi organisation and function in non-adherent fibroblasts. Biol Open 2023; 12:bio059669. [PMID: 36946871 PMCID: PMC10187640 DOI: 10.1242/bio.059669] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 03/13/2023] [Indexed: 03/23/2023] Open
Abstract
Arf1 belongs to the Arf family of small GTPases that localise at the Golgi and plasma membrane. Active Arf1 plays a crucial role in regulating Golgi organisation and function. In mouse fibroblasts, loss of adhesion triggers a consistent drop (∼50%) in Arf1 activation that causes the Golgi to disorganise but not fragment. In suspended cells, the trans-Golgi (GalTase) disperses more prominently than cis-Golgi (Man II), accompanied by increased active Arf1 (detected using GFP-ABD: ARHGAP10 Arf1 binding domain) associated with the cis-Golgi compartment. Re-adhesion restores Arf1 activation at the trans-Golgi as it reorganises. Arf1 activation at the Golgi is regulated by Arf1 Guanine nucleotide exchange factors (GEFs), GBF1, and BIG1/2. In non-adherent fibroblasts, the cis-medial Golgi provides a unique setting to test and understand the role GEF-mediated Arf1 activation has in regulating Golgi organisation. Labelled with Man II-GFP, non-adherent fibroblasts treated with increasing concentrations of Brefeldin-A (BFA) (which inhibits BIG1/2 and GBF1) or Golgicide A (GCA) (which inhibits GBF1 only) comparably decrease active Arf1 levels. They, however, cause a concentration-dependent increase in cis-medial Golgi fragmentation and fusion with the endoplasmic reticulum (ER). Using selected BFA and GCA concentrations, we find a change in the kinetics of Arf1 inactivation could mediate this by regulating cis-medial Golgi localisation of GBF1. On loss of adhesion, a ∼50% drop in Arf1 activation over 120 min causes the Golgi to disorganise. The kinetics of this drop, when altered by BFA or GCA treatment causes a similar decline in Arf1 activation but over 10 min. This causes the Golgi to now fragment which affects cell surface glycosylation and re-adherent cell spreading. Using non-adherent fibroblasts this study reveals the kinetics of Arf1 inactivation, with active Arf1 levels, to be vital for Golgi organisation and function.
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Affiliation(s)
- Rajeshwari B.R.
- Indian Institute of Science Education and Research (IISER) Pune, Dr Homi Bhabha Road, Pashan, Pune, Maharashtra 411008, India
| | - Nikita Shah
- Indian Institute of Science Education and Research (IISER) Pune, Dr Homi Bhabha Road, Pashan, Pune, Maharashtra 411008, India
| | - Prachi Joshi
- Indian Institute of Science Education and Research (IISER) Pune, Dr Homi Bhabha Road, Pashan, Pune, Maharashtra 411008, India
| | - M. S. Madhusudan
- Indian Institute of Science Education and Research (IISER) Pune, Dr Homi Bhabha Road, Pashan, Pune, Maharashtra 411008, India
| | - Nagaraj Balasubramanian
- Indian Institute of Science Education and Research (IISER) Pune, Dr Homi Bhabha Road, Pashan, Pune, Maharashtra 411008, India
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3
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Golgipathies reveal the critical role of the sorting machinery in brain and skeletal development. Nat Commun 2022; 13:7397. [PMID: 36456556 PMCID: PMC9715697 DOI: 10.1038/s41467-022-35101-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 11/18/2022] [Indexed: 12/03/2022] Open
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4
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Pellegrina D, Bahcheli AT, Krassowski M, Reimand J. Human phospho-signaling networks of SARS-CoV-2 infection are rewired by population genetic variants. Mol Syst Biol 2022; 18:e10823. [PMID: 35579274 PMCID: PMC9112486 DOI: 10.15252/msb.202110823] [Citation(s) in RCA: 6] [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: 11/19/2021] [Revised: 04/26/2022] [Accepted: 04/27/2022] [Indexed: 11/23/2022] Open
Abstract
SARS-CoV-2 infection hijacks signaling pathways and induces protein-protein interactions between human and viral proteins. Human genetic variation may impact SARS-CoV-2 infection and COVID-19 pathology; however, the genetic variation in these signaling networks remains uncharacterized. Here, we studied human missense single nucleotide variants (SNVs) altering phosphorylation sites modulated by SARS-CoV-2 infection, using machine learning to identify amino acid substitutions altering kinase-bound sequence motifs. We found 2,033 infrequent phosphorylation-associated SNVs (pSNVs) that are enriched in sequence motif alterations, potentially reflecting the evolution of signaling networks regulating host defenses. Proteins with pSNVs are involved in viral life cycle and host responses, including RNA splicing, interferon response (TRIM28), and glucose homeostasis (TBC1D4) with potential associations with COVID-19 comorbidities. pSNVs disrupt CDK and MAPK substrate motifs and replace these with motifs of Tank Binding Kinase 1 (TBK1) involved in innate immune responses, indicating consistent rewiring of signaling networks. Several pSNVs associate with severe COVID-19 and hospitalization (STARD13, ARFGEF2). Our analysis highlights potential genetic factors contributing to inter-individual variation of SARS-CoV-2 infection and COVID-19 and suggests leads for mechanistic and translational studies.
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Affiliation(s)
- Diogo Pellegrina
- Computational Biology ProgramOntario Institute for Cancer ResearchTorontoONCanada
| | - Alexander T Bahcheli
- Computational Biology ProgramOntario Institute for Cancer ResearchTorontoONCanada
- Department of Molecular GeneticsUniversity of TorontoTorontoONCanada
| | - Michal Krassowski
- Medical Sciences DivisionNuffield Department of Women's and Reproductive HealthUniversity of OxfordOxfordUK
| | - Jüri Reimand
- Computational Biology ProgramOntario Institute for Cancer ResearchTorontoONCanada
- Department of Molecular GeneticsUniversity of TorontoTorontoONCanada
- Department of Medical BiophysicsUniversity of TorontoTorontoONCanada
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5
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Pavišić V, Mahmutefendić Lučin H, Blagojević Zagorac G, Lučin P. Arf GTPases Are Required for the Establishment of the Pre-Assembly Compartment in the Early Phase of Cytomegalovirus Infection. Life (Basel) 2021; 11:867. [PMID: 34440611 PMCID: PMC8399710 DOI: 10.3390/life11080867] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/16/2021] [Accepted: 08/18/2021] [Indexed: 12/31/2022] Open
Abstract
Shortly after entering the cells, cytomegaloviruses (CMVs) initiate massive reorganization of cellular endocytic and secretory pathways, which results in the forming of the cytoplasmic virion assembly compartment (AC). We have previously shown that the formation of AC in murine CMV- (MCMV) infected cells begins in the early phase of infection (at 4-6 hpi) with the pre-AC establishment. Pre-AC comprises membranes derived from the endosomal recycling compartment, early endosomes, and the trans-Golgi network, which is surrounded by fragmented Golgi cisterns. To explore the importance of Arf GTPases in the biogenesis of the pre-AC, we infected Balb 3T3 cells with MCMV and analyzed the expression and intracellular localization of Arf proteins in the early phases (up to 16 hpi) of infection and the development of pre-AC in cells with a knockdown of Arf protein expression by small interfering RNAs (siRNAs). Herein, we show that even in the early phase, MCMVs cause massive reorganization of the Arf system of the host cells and induce the over-recruitment of Arf proteins onto the membranes of pre-AC. Knockdown of Arf1, Arf3, Arf4, or Arf6 impaired the establishment of pre-AC. However, the knockdown of Arf1 and Arf6 also abolished the establishment of infection. Our study demonstrates that Arf GTPases are required for different steps of early cytomegalovirus infection, including the establishment of the pre-AC.
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Affiliation(s)
- Valentino Pavišić
- Department of Physiology and Immunology, Faculty of Medicine, University of Rijeka, 51000 Rijeka, Croatia; (V.P.); (H.M.L.); (P.L.)
| | - Hana Mahmutefendić Lučin
- Department of Physiology and Immunology, Faculty of Medicine, University of Rijeka, 51000 Rijeka, Croatia; (V.P.); (H.M.L.); (P.L.)
- Nursing Department, University North, University Center Varaždin, Jurja Križanića 31b, 42000 Varaždin, Croatia
| | - Gordana Blagojević Zagorac
- Department of Physiology and Immunology, Faculty of Medicine, University of Rijeka, 51000 Rijeka, Croatia; (V.P.); (H.M.L.); (P.L.)
- Nursing Department, University North, University Center Varaždin, Jurja Križanića 31b, 42000 Varaždin, Croatia
| | - Pero Lučin
- Department of Physiology and Immunology, Faculty of Medicine, University of Rijeka, 51000 Rijeka, Croatia; (V.P.); (H.M.L.); (P.L.)
- Nursing Department, University North, University Center Varaždin, Jurja Križanića 31b, 42000 Varaždin, Croatia
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6
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Adarska P, Wong-Dilworth L, Bottanelli F. ARF GTPases and Their Ubiquitous Role in Intracellular Trafficking Beyond the Golgi. Front Cell Dev Biol 2021; 9:679046. [PMID: 34368129 PMCID: PMC8339471 DOI: 10.3389/fcell.2021.679046] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 06/30/2021] [Indexed: 11/13/2022] Open
Abstract
Molecular switches of the ADP-ribosylation factor (ARF) GTPase family coordinate intracellular trafficking at all sorting stations along the secretory pathway, from the ER-Golgi-intermediate compartment (ERGIC) to the plasma membrane (PM). Their GDP-GTP switch is essential to trigger numerous processes, including membrane deformation, cargo sorting and recruitment of downstream coat proteins and effectors, such as lipid modifying enzymes. While ARFs (in particular ARF1) had mainly been studied in the context of coat protein recruitment at the Golgi, COPI/clathrin-independent roles have emerged in the last decade. Here we review the roles of human ARF1-5 GTPases in cellular trafficking with a particular emphasis on their roles in post-Golgi secretory trafficking and in sorting in the endo-lysosomal system.
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Affiliation(s)
- Petia Adarska
- Institut für Biochemie, Freie Universität Berlin, Berlin, Germany
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7
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BIG3 and BIG5 Redundantly Mediate Vesicle Trafficking in Arabidopsis. Biomolecules 2021; 11:biom11050732. [PMID: 34069034 PMCID: PMC8156563 DOI: 10.3390/biom11050732] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/08/2021] [Accepted: 05/12/2021] [Indexed: 12/02/2022] Open
Abstract
Vesicle trafficking plays an important role in delivering a diverse range of cargoes between different membranous systems in eukaryotes. It is well documented that the brefeldin A (BFA)-inhibited guanine nucleotide exchange factor (GEF), named BIG, regulates vesicle budding at the trans-Golgi network (TGN) and recycling endosomes through activating the ADP-ribosylation factor (ARFs). Among the five BIGs in Arabidopsis, BIG5 is characterized to mediate ARF-dependent trafficking at the plasma membrane or endosomes while the members from BIG1 to BIG4 (BIG1-BIG4) at the TGN in the secretory pathway. However, evidence is increasing to suggest that BIG5 can function redundantly with BIG1-BIG4 to regulate vesicular trafficking in response to various intra- and extra-cellular stimuli. In this study, our genetic analysis showed that BIG5 played an overlapping role at least with BIG3 in cell proliferation. To elucidate molecular mechanisms underlying the BIG5- and BIG3-regulated biological processes, we examined the effect of BIGs on expression patterns of the two transmembrane proteins, PINFORMED 2 (PIN2) epically localized in root epidermal cells and the regulator of G protein signaling 1 (RGS1) localized in the plasma membrane. Our data showed that the PIN2 polar distribution was slightly reduced in big3 big5 in the absence of BFA, and it was significantly reduced by the treatment of 0.1 µM BFA in big3 big5. Further analysis revealed that BFA bodies derived from the plasma membrane were only observed in wild type (WT), big3 and big5 cells, but not in the big3 big5 cells. These results indicate that BIG5 and BIG3 are functionally redundant in the endosome recycling pathway from the plasma membrane to TGN. On the other hand, the single BIG3 or BIG5 mutation had no effect on the plasma membrane expression of RGS1, whereas the double mutations in BIG3 and BIG5 led to a significant amount of RGS1 retained in the vesicle, indicating that BIG3 and BIG5 act redundantly in mediating protein trafficking. Furthermore, transmission electron microscopy assays showed that Golgi ultrastructure in big3 big5 cells was abnormal and similar to that in BFA-treated WT cells. Taken together, our data provide several new lines of evidence supporting that BIGs play a redundant role in vesicular trafficking and probably also in maintaining the Golgi structural integrity in Arabidopsis.
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8
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Fujii S, Kurokawa K, Tago T, Inaba R, Takiguchi A, Nakano A, Satoh T, Satoh AK. Sec71 separates Golgi stacks in Drosophila S2 cells. J Cell Sci 2020; 133:jcs245571. [PMID: 33262309 PMCID: PMC10668125 DOI: 10.1242/jcs.245571] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 11/18/2020] [Indexed: 01/19/2023] Open
Abstract
Golgi stacks are the basic structural units of the Golgi. Golgi stacks are separated from each other and scattered in the cytoplasm of Drosophila cells. Here, we report that the ARF-GEF inhibitor Brefeldin A (BFA) induces the formation of BFA bodies, which are aggregates of Golgi stacks, trans-Golgi networks and recycling endosomes. Recycling endosomes are located in the centers of BFA bodies, while Golgi stacks surround them on their trans sides. Live imaging of S2 cells revealed that Golgi stacks repeatedly merged and separated on their trans sides, and BFA caused successive merger by inhibiting separation, forming BFA bodies. S2 cells carrying genome-edited BFA-resistant mutant Sec71M717L did not form BFA bodies at high concentrations of BFA; S2 cells carrying genome-edited BFA-hypersensitive mutant Sec71F713Y produced BFA bodies at low concentrations of BFA. These results indicate that Sec71 is the sole BFA target for BFA body formation and controls Golgi stack separation. Finally, we showed that impairment of Sec71 in fly photoreceptors induces BFA body formation, with accumulation of both apical and basolateral cargoes, resulting in inhibition of polarized transport.
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Affiliation(s)
- Syara Fujii
- Program of Life and Environmental Science, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
| | - Kazuo Kurokawa
- Live Cell Super-Resolution Imaging Research Team, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Tatsuya Tago
- Program of Life and Environmental Science, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
| | - Ryota Inaba
- Program of Life and Environmental Science, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
| | - Arata Takiguchi
- Program of Life and Environmental Science, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
| | - Akihiko Nakano
- Live Cell Super-Resolution Imaging Research Team, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Takunori Satoh
- Program of Life and Environmental Science, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
| | - Akiko K Satoh
- Program of Life and Environmental Science, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
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9
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Seoane PI, Lee B, Hoyle C, Yu S, Lopez-Castejon G, Lowe M, Brough D. The NLRP3-inflammasome as a sensor of organelle dysfunction. J Cell Biol 2020; 219:191204. [PMID: 33044555 PMCID: PMC7543090 DOI: 10.1083/jcb.202006194] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 09/18/2020] [Accepted: 09/18/2020] [Indexed: 02/08/2023] Open
Abstract
Diverse pathogen- and damage-associated stresses drive inflammation via activation of the multimolecular NLRP3-inflammasome complex. How the effects of diverse stimuli are integrated by the cell to regulate NLRP3 has been the subject of intense research, and yet an accepted unifying hypothesis for the control of NLRP3 remains elusive. Here, we review the literature on the effects of NLRP3-activating stimuli on subcellular organelles and conclude that a shared feature of NLRP3-activating stresses is an organelle dysfunction. In particular, we propose that the endosome may be more important than previously recognized as a signal-integrating hub for NLRP3 activation in response to many stimuli and may also link to the dysfunction of other organelles. In addition, NLRP3-inflammasome-activating stimuli trigger diverse posttranslational modifications of NLRP3 that are important in controlling its activation. Future research should focus on how organelles respond to specific NLRP3-activating stimuli, and how this relates to posttranslational modifications, to delineate the organellar control of NLRP3.
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Affiliation(s)
- Paula I. Seoane
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine, and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK,The Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, UK
| | - Bali Lee
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine, and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK,The Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, UK
| | - Christopher Hoyle
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine, and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK,The Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, UK
| | - Shi Yu
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine, and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK,The Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, UK
| | - Gloria Lopez-Castejon
- Division of Infection, Immunity, and Respiratory Medicine, School of Biological Sciences, Faculty of Biology, Medicine, and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK,The Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, UK
| | - Martin Lowe
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology, Medicine, and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - David Brough
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine, and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK,The Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, UK,Correspondence to David Brough:
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10
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Lučin P, Jug Vučko N, Karleuša L, Mahmutefendić Lučin H, Blagojević Zagorac G, Lisnić B, Pavišić V, Marcelić M, Grabušić K, Brizić I, Lukanović Jurić S. Cytomegalovirus Generates Assembly Compartment in the Early Phase of Infection by Perturbation of Host-Cell Factors Recruitment at the Early Endosome/Endosomal Recycling Compartment/Trans-Golgi Interface. Front Cell Dev Biol 2020; 8:563607. [PMID: 33042998 PMCID: PMC7516400 DOI: 10.3389/fcell.2020.563607] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 08/18/2020] [Indexed: 12/02/2022] Open
Abstract
Beta-herpesviruses develop a unique structure within the infected cell known as an assembly compartment (AC). This structure, as large as the nucleus, is composed of host-cell-derived membranous elements. The biogenesis of the AC and its contribution to the final stages of beta-herpesvirus assembly are still unclear. In this study, we performed a spatial and temporal analysis of the AC in cells infected with murine CMV (MCMV), a member of the beta-herpesvirus family, using a panel of markers that characterize membranous organelle system. Out of 64 markers that were analyzed, 52 were cytosolic proteins that are recruited to membranes as components of membrane-shaping regulatory cascades. The analysis demonstrates that MCMV infection extensively reorganizes interface between early endosomes (EE), endosomal recycling compartment (ERC), and the trans-Golgi network (TGN), resulting in expansion of various EE-ERC-TGN intermediates that fill the broad area of the inner AC. These intermediates are displayed as over-recruitment of host-cell factors that control membrane flow at the EE-ERC-TGN interface. Most of the reorganization is accomplished in the early (E) phase of infection, indicating that the AC biogenesis is controlled by MCMV early genes. Although it is known that CMV infection affects the expression of a large number of host-cell factors that control membranous system, analysis of the host-cell transcriptome and protein expression in the E phase of infection demonstrated no sufficiently significant alteration in expression levels of analyzed markers. Thus, our study demonstrates that MCMV-encoded early phase function targets recruitment cascades of host cell-factors that control membranous flow at the EE-ERC-TGN interface in order to initiate the development of the AC.
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Affiliation(s)
- Pero Lučin
- Department of Physiology and Immunology, Faculty of Medicine, University of Rijeka, Rijeka, Croatia.,University North, University Center Varaždin, Varaždin, Croatia
| | - Natalia Jug Vučko
- Department of Physiology and Immunology, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
| | - Ljerka Karleuša
- Department of Physiology and Immunology, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
| | - Hana Mahmutefendić Lučin
- Department of Physiology and Immunology, Faculty of Medicine, University of Rijeka, Rijeka, Croatia.,University North, University Center Varaždin, Varaždin, Croatia
| | - Gordana Blagojević Zagorac
- Department of Physiology and Immunology, Faculty of Medicine, University of Rijeka, Rijeka, Croatia.,University North, University Center Varaždin, Varaždin, Croatia
| | - Berislav Lisnić
- Department of Histology and Embryology, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
| | - Valentino Pavišić
- Department of Physiology and Immunology, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
| | - Marina Marcelić
- Department of Physiology and Immunology, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
| | - Kristina Grabušić
- Department of Physiology and Immunology, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
| | - Ilija Brizić
- Department of Histology and Embryology, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
| | - Silvija Lukanović Jurić
- Department of Physiology and Immunology, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
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11
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Okamoto S, Naito T, Shigetomi R, Kosugi Y, Nakayama K, Takatsu H, Shin HW. The N- or C-terminal cytoplasmic regions of P4-ATPases determine their cellular localization. Mol Biol Cell 2020; 31:2115-2124. [PMID: 32614659 PMCID: PMC7530900 DOI: 10.1091/mbc.e20-04-0225] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Mammalian P4-ATPases specifically localize to the plasma membrane and the membranes of intracellular compartments. P4-ATPases contain 10 transmembrane domains, and their N- and C-terminal (NT and CT) regions face the cytoplasm. Among the ATP10 and ATP11 proteins of P4-ATPases, ATP10A, ATP10D, ATP11A, and ATP11C localize to the plasma membrane, while ATP10B and ATP11B localize to late endosomes and early/recycling endosomes, respectively. We previously showed that the NT region of ATP9B is critical for its localization to the Golgi apparatus, while the CT regions of ATP11C isoforms are critical for Ca2+-dependent endocytosis or polarized localization at the plasma membrane. Here, we conducted a comprehensive analysis of chimeric proteins and found that the NT region of ATP10 proteins and the CT region of ATP11 proteins are responsible for their specific subcellular localization. Importantly, the ATP10B NT and the ATP11B CT regions were found to harbor a trafficking and/or targeting signal that allows these P4-ATPases to localize to late endosomes and early/recycling endosomes, respectively. Moreover, dileucine residues in the NT region of ATP10B were required for its trafficking to endosomal compartments. These results suggest that the NT and CT sequences of P4-ATPases play a key role in their intracellular trafficking.
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Affiliation(s)
- Sayuri Okamoto
- Department of Physiological Chemistry, Graduate School, Sakyo-ku, Kyoto 606-8501, Japan
| | - Tomoki Naito
- Department of Physiological Chemistry, Graduate School, Sakyo-ku, Kyoto 606-8501, Japan
| | - Ryo Shigetomi
- Department of Physiological Chemistry, Graduate School, Sakyo-ku, Kyoto 606-8501, Japan
| | - Yusuke Kosugi
- Faculty of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Kazuhisa Nakayama
- Department of Physiological Chemistry, Graduate School, Sakyo-ku, Kyoto 606-8501, Japan
| | - Hiroyuki Takatsu
- Department of Physiological Chemistry, Graduate School, Sakyo-ku, Kyoto 606-8501, Japan
| | - Hye-Won Shin
- Department of Physiological Chemistry, Graduate School, Sakyo-ku, Kyoto 606-8501, Japan
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12
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Walton K, Leier A, Sztul E. Regulating the regulators: role of phosphorylation in modulating the function of the GBF1/BIG family of Sec7 ARF-GEFs. FEBS Lett 2020; 594:2213-2226. [PMID: 32333796 DOI: 10.1002/1873-3468.13798] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 04/15/2020] [Accepted: 04/16/2020] [Indexed: 12/15/2022]
Abstract
Membrane traffic between secretory and endosomal compartments is vesicle-mediated and must be tightly balanced to maintain a physiological compartment size. Vesicle formation is initiated by guanine nucleotide exchange factors (GEFs) that activate the ARF family of small GTPases. Regulatory mechanisms, including reversible phosphorylation, allow ARF-GEFs to support vesicle formation only at the right time and place in response to cellular needs. Here, we review current knowledge of how the Golgi-specific brefeldin A-resistance factor 1 (GBF1)/brefeldin A-inhibited guanine nucleotide exchange protein (BIG) family of ARF-GEFs is influenced by phosphorylation and use predictive paradigms to propose new regulatory paradigms. We describe a conserved cluster of phosphorylation sites within the N-terminal domains of the GBF1/BIG ARF-GEFs and suggest that these sites may respond to homeostatic signals related to cell growth and division. In the C-terminal region, GBF1 shows phosphorylation sites clustered differently as compared with the similar configuration found in both BIG1 and BIG2. Despite this similarity, BIG1 and BIG2 phosphorylation patterns are divergent in other domains. The different clustering of phosphorylation sites suggests that the nonconserved sites may represent distinct regulatory nodes and specify the function of GBF1, BIG1, and BIG2.
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Affiliation(s)
- Kendall Walton
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, AL, USA
| | - Andre Leier
- Department of Genetics, University of Alabama at Birmingham, AL, USA
| | - Elizabeth Sztul
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, AL, USA
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13
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Identification of Genes Required for Apical Protein Trafficking in Drosophila Photoreceptor Cells. G3-GENES GENOMES GENETICS 2019; 9:4007-4017. [PMID: 31649044 PMCID: PMC6893196 DOI: 10.1534/g3.119.400635] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Drosophila melanogaster photoreceptor cells are highly polarized epithelial cells. Their apical membrane is further subdivided into the stalk membrane and the light-sensing rhabdomere. The photo-pigment Rhodopsin1 (Rh1) localizes to the rhabdomere, whereas the apical determinant Crumbs (Crb) is enriched at the stalk membrane. The proteoglycan Eyes shut (Eys) is secreted through the apical membrane into an inter-rhabdomeral space. Rh1, Crb, and Eys are essential for the development of photoreceptor cells, normal vision, and photoreceptor cell survival. Human orthologs of all three proteins have been linked to retinal degenerative diseases. Here, we describe an RNAi-based screen examining the importance of 237 trafficking-related genes in apical trafficking of Eys, Rh1, and Crb. We found 28 genes that have an effect on the localization and/or levels of these apical proteins and analyzed several factors in more detail. We show that the Arf GEF protein Sec71 is required for biosynthetic traffic of both apical and basolateral proteins, that the exocyst complex and the microtubule-based motor proteins dynein and kinesin promote the secretion of Eys and Rh1, and that Syntaxin 7/Avalanche controls the endocytosis of Rh1, Eys, and Crb.
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14
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Teoh J, Subramanian N, Pero ME, Bartolini F, Amador A, Kanber A, Williams D, Petri S, Yang M, Allen AS, Beal J, Haut SR, Frankel WN. Arfgef1 haploinsufficiency in mice alters neuronal endosome composition and decreases membrane surface postsynaptic GABA A receptors. Neurobiol Dis 2019; 134:104632. [PMID: 31678406 DOI: 10.1016/j.nbd.2019.104632] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 09/23/2019] [Accepted: 10/01/2019] [Indexed: 12/23/2022] Open
Abstract
ARFGEF1 encodes a guanine exchange factor involved in intracellular vesicle trafficking, and is a candidate gene for childhood genetic epilepsies. To model ARFGEF1 haploinsufficiency observed in a recent Lennox Gastaut Syndrome patient, we studied a frameshift mutation (Arfgef1fs) in mice. Arfgef1fs/+ pups exhibit signs of developmental delay, and Arfgef1fs/+ adults have a significantly decreased threshold to induced seizures but do not experience spontaneous seizures. Histologically, the Arfgef1fs/+ brain exhibits a disruption in the apical lining of the dentate gyrus and altered spine morphology of deep layer neurons. In primary hippocampal neuron culture, dendritic surface and synaptic but not total GABAA receptors (GABAAR) are reduced in Arfgef1fs/+ neurons with an accompanying decrease in the number of GABAAR-containing recycling endosomes in cell body. Arfgef1fs/+ neurons also display differences in the relative ratio of Arf6+:Rab11+:TrfR+ recycling endosomes. Although the GABAAR-containing early endosomes in Arfgef1fs/+ neurons are comparable to wildtype, Arfgef1fs/+ neurons show an increase in the number of GABAAR-containing lysosomes in dendrite and cell body. Together, the altered endosome composition and decreased neuronal surface GABAAR results suggests a mechanism whereby impaired neuronal inhibition leads to seizure susceptibility.
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Affiliation(s)
- JiaJie Teoh
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States of America.
| | - Narayan Subramanian
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States of America
| | - Maria Elena Pero
- Department of Pathology & Cell Biology, Columbia University Irving Medical Center, New York, NY, United States of America; Department of Veterinary Medicine and Animal Production, University of Naples Federico II, Naples, Italy
| | - Francesca Bartolini
- Department of Pathology & Cell Biology, Columbia University Irving Medical Center, New York, NY, United States of America
| | - Ariadna Amador
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States of America
| | - Ayla Kanber
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States of America
| | - Damian Williams
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States of America
| | - Sabrina Petri
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States of America
| | - Mu Yang
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States of America
| | - Andrew S Allen
- Department of Biostatistics and Bioinformatics, Duke University, Durham, NC, United States of America
| | - Jules Beal
- The Saul R. Korey Department of Neurology, Montefiore Medical Center and Albert Einstein College of Medicine, Bronx, NY, United States of America
| | - Sheryl R Haut
- The Saul R. Korey Department of Neurology, Montefiore Medical Center and Albert Einstein College of Medicine, Bronx, NY, United States of America
| | - Wayne N Frankel
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States of America; Department of Genetic and Development, Columbia University Irving Medical Center, New York, NY, United States of America
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15
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The Guanine Nucleotide Exchange Factor GBF1 Participates in Rotavirus Replication. J Virol 2019; 93:JVI.01062-19. [PMID: 31270230 DOI: 10.1128/jvi.01062-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 07/01/2019] [Indexed: 01/06/2023] Open
Abstract
Cellular and viral factors participate in the replication cycle of rotavirus. We report that the guanine nucleotide exchange factor GBF1, which activates the small GTPase Arf1 to induce COPI transport processes, is required for rotavirus replication since knocking down GBF1 expression by RNA interference or inhibiting its activity by treatment with brefeldin A (BFA) or Golgicide A (GCA) significantly reduces the yield of infectious viral progeny. This reduction in virus yield was related to a block in virus assembly, since in the presence of either BFA or GCA, the assembly of infectious mature triple-layered virions was significantly prevented and only double-layered particles were detected. We report that the catalytic activity of GBF1, but not the activation of Arf1, is essential for the assembly of the outer capsid of rotavirus. We show that both BFA and GCA, as well as interfering with the synthesis of GBF1, alter the electrophoretic mobility of glycoproteins VP7 and NSP4 and block the trimerization of the virus surface protein VP7, a step required for its incorporation into virus particles. Although a posttranslational modification of VP7 (other than glycosylation) could be related to the lack of trimerization, we found that NSP4 might also be involved in this process, since knocking down its expression reduces VP7 trimerization. In support, recombinant VP7 protein overexpressed in transfected cells formed trimers only when cotransfected with NSP4.IMPORTANCE Rotavirus, a member of the family Reoviridae, is the major cause of severe diarrhea in children and young animals worldwide. Despite significant advances in the characterization of the biology of this virus, the mechanisms involved in morphogenesis of the virus particle are still poorly understood. In this work, we show that the guanine nucleotide exchange factor GBF1, relevant for COPI/Arf1-mediated cellular vesicular transport, participates in the replication cycle of the virus, influencing the correct processing of viral glycoproteins VP7 and NSP4 and the assembly of the virus surface proteins VP7 and VP4.
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16
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Newton T, Allison R, Edgar JR, Lumb JH, Rodger CE, Manna PT, Rizo T, Kohl Z, Nygren AOH, Arning L, Schüle R, Depienne C, Goldberg L, Frahm C, Stevanin G, Durr A, Schöls L, Winner B, Beetz C, Reid E. Mechanistic basis of an epistatic interaction reducing age at onset in hereditary spastic paraplegia. Brain 2019; 141:1286-1299. [PMID: 29481671 PMCID: PMC5917785 DOI: 10.1093/brain/awy034] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 01/04/2018] [Indexed: 12/20/2022] Open
Abstract
Many genetic neurological disorders exhibit variable expression within affected families, often exemplified by variations in disease age at onset. Epistatic effects (i.e. effects of modifier genes on the disease gene) may underlie this variation, but the mechanistic basis for such epistatic interactions is rarely understood. Here we report a novel epistatic interaction between SPAST and the contiguous gene DPY30, which modifies age at onset in hereditary spastic paraplegia, a genetic axonopathy. We found that patients with hereditary spastic paraplegia caused by genomic deletions of SPAST that extended into DPY30 had a significantly younger age at onset. We show that, like spastin, the protein encoded by SPAST, the DPY30 protein controls endosomal tubule fission, traffic of mannose 6-phosphate receptors from endosomes to the Golgi, and lysosomal ultrastructural morphology. We propose that additive effects on this pathway explain the reduced age at onset of hereditary spastic paraplegia in patients who are haploinsufficient for both genes.
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Affiliation(s)
- Timothy Newton
- Department of Medical Genetics and Cambridge Institute for Medical Research, University of Cambridge, UK
| | - Rachel Allison
- Department of Medical Genetics and Cambridge Institute for Medical Research, University of Cambridge, UK
| | - James R Edgar
- Department of Clinical Biochemistry and Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Jennifer H Lumb
- Department of Medical Genetics and Cambridge Institute for Medical Research, University of Cambridge, UK
| | - Catherine E Rodger
- Department of Medical Genetics and Cambridge Institute for Medical Research, University of Cambridge, UK
| | - Paul T Manna
- Department of Clinical Biochemistry and Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Tania Rizo
- Department of Stem Cell Biology, Friedrich-Alexander University Erlangen-Nuernberg (FAU), Erlangen, Germany
| | - Zacharias Kohl
- Department of Molecular Neurology, Friedrich-Alexander University Erlangen-Nuernberg (FAU), Erlangen, Germany
| | | | - Larissa Arning
- Department of Human Genetics, Ruhr-University, Bochum, Germany
| | - Rebecca Schüle
- Center for Neurology and Hertie Institute for Clinical Brain Research, Eberhard-Karls-University, 72076 Tübingen, Germany.,German Center of Neurodegenerative Diseases (DZNE), 72076 Tübingen, Germany
| | - Christel Depienne
- ICM Brain and Spine Institute, INSERM U1127, CNRS UMR7225, Sorbonne Universites, UPMC Univ Paris VI UMR_S1127, Paris, France.,APHP, Genetic Department, Pitie-Salpêtrière University Hospital, Paris, France
| | - Lisa Goldberg
- Department of Clinical Chemistry and Laboratory Diagnostics, Jena University Hospital, Jena, Germany
| | - Christiane Frahm
- Hans Berger Department of Neurology, Jena University Hospital, Jena, Germany
| | - Giovanni Stevanin
- ICM Brain and Spine Institute, INSERM U1127, CNRS UMR7225, Sorbonne Universites, UPMC Univ Paris VI UMR_S1127, Paris, France.,APHP, Genetic Department, Pitie-Salpêtrière University Hospital, Paris, France.,Ecole Pratique des Hautes Etudes, PSL Research University, Paris, France
| | - Alexandra Durr
- ICM Brain and Spine Institute, INSERM U1127, CNRS UMR7225, Sorbonne Universites, UPMC Univ Paris VI UMR_S1127, Paris, France.,APHP, Genetic Department, Pitie-Salpêtrière University Hospital, Paris, France
| | - Ludger Schöls
- Center for Neurology and Hertie Institute for Clinical Brain Research, Eberhard-Karls-University, 72076 Tübingen, Germany.,German Center of Neurodegenerative Diseases (DZNE), 72076 Tübingen, Germany
| | - Beate Winner
- Department of Molecular Neurology, Friedrich-Alexander University Erlangen-Nuernberg (FAU), Erlangen, Germany
| | - Christian Beetz
- Department of Clinical Chemistry and Laboratory Diagnostics, Jena University Hospital, Jena, Germany
| | - Evan Reid
- Department of Medical Genetics and Cambridge Institute for Medical Research, University of Cambridge, UK
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17
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Lu FI, Wang YT, Wang YS, Wu CY, Li CC. Involvement of BIG1 and BIG2 in regulating VEGF expression and angiogenesis. FASEB J 2019; 33:9959-9973. [PMID: 31199673 DOI: 10.1096/fj.201900342rr] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
VEGF stimulates the formation of new blood vessels by inducing endothelial cell (EC) proliferation and migration. Brefeldin A (BFA)-inhibited guanine nucleotide-exchange protein (BIG)1 and 2 accelerate the replacement of bound GDP with GTP to activate ADP-ribosylation factor (Arf)1, which regulates vesicular transport between the Golgi and plasma membrane. Although it has been reported that treating cells with BFA interferes with Arf1 activation to inhibit VEGF secretion, the role of BIG1 and BIG2 in VEGF trafficking and expression, EC migration and proliferation, and vascular development remains unknown. Here, we found that inactivation of Arf1 reduced VEGF secretion but did not affect the levels of VEGF protein. Interestingly, however, BIG1 and BIG2 knockdown significantly decreased the levels of VEGF mRNA and protein in glioblastoma U251 cells and HUVECs. Furthermore, depletion of BIG1 and BIG2 inhibited HUVEC angiogenesis by diminishing cell migration. Angioblast migration and intersegmental vessel sprouting were also impaired when the BIG2 homolog, Arf guanine nucleotide exchange factor (arfgef)2, was knocked down in zebrafish with endothelial expression of green fluorescent protein (GFP). Depletion of arfgef2 by clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 (Cas9) also caused defects in vascular development of zebrafish embryos. Taken together, these data reveal that BIG1 and BIG2 participate in endothelial cell angiogenesis.-Lu, F.-I., Wang, Y.-T., Wang, Y.-S., Wu, C.-Y., Li, C.-C. Involvement of BIG1 and BIG2 in regulating VEGF expression and angiogenesis.
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Affiliation(s)
- Fu-I Lu
- Department of Biotechnology and Bioindustry Sciences, National Cheng Kung University, Tainan, Taiwan.,The Integrative Evolutionary Galliforms Genomics Research (iEGG) and Animal Biotechnology Center, National Chung Hsing University, Taichung, Taiwan
| | - Yi-Ting Wang
- Department of Life Sciences, National Cheng Kung University, Tainan, Taiwan
| | - Yi-Shan Wang
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan
| | - Chang-Yi Wu
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan
| | - Chun-Chun Li
- Department of Life Sciences, National Cheng Kung University, Tainan, Taiwan
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18
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Sztul E, Chen PW, Casanova JE, Cherfils J, Dacks JB, Lambright DG, Lee FJS, Randazzo PA, Santy LC, Schürmann A, Wilhelmi I, Yohe ME, Kahn RA. ARF GTPases and their GEFs and GAPs: concepts and challenges. Mol Biol Cell 2019; 30:1249-1271. [PMID: 31084567 PMCID: PMC6724607 DOI: 10.1091/mbc.e18-12-0820] [Citation(s) in RCA: 149] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 02/26/2019] [Accepted: 03/11/2019] [Indexed: 12/12/2022] Open
Abstract
Detailed structural, biochemical, cell biological, and genetic studies of any gene/protein are required to develop models of its actions in cells. Studying a protein family in the aggregate yields additional information, as one can include analyses of their coevolution, acquisition or loss of functionalities, structural pliability, and the emergence of shared or variations in molecular mechanisms. An even richer understanding of cell biology can be achieved through evaluating functionally linked protein families. In this review, we summarize current knowledge of three protein families: the ARF GTPases, the guanine nucleotide exchange factors (ARF GEFs) that activate them, and the GTPase-activating proteins (ARF GAPs) that have the ability to both propagate and terminate signaling. However, despite decades of scrutiny, our understanding of how these essential proteins function in cells remains fragmentary. We believe that the inherent complexity of ARF signaling and its regulation by GEFs and GAPs will require the concerted effort of many laboratories working together, ideally within a consortium to optimally pool information and resources. The collaborative study of these three functionally connected families (≥70 mammalian genes) will yield transformative insights into regulation of cell signaling.
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Affiliation(s)
- Elizabeth Sztul
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Pei-Wen Chen
- Department of Biology, Williams College, Williamstown, MA 01267
| | - James E. Casanova
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22908
| | - Jacqueline Cherfils
- Laboratoire de Biologie et Pharmacologie Appliquée, CNRS and Ecole Normale Supérieure Paris-Saclay, 94235 Cachan, France
| | - Joel B. Dacks
- Division of Infectious Disease, Department of Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - David G. Lambright
- Program in Molecular Medicine and Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Amherst, MA 01605
| | - Fang-Jen S. Lee
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan
| | | | - Lorraine C. Santy
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802
| | - Annette Schürmann
- German Institute of Human Nutrition, 85764 Potsdam-Rehbrücke, Germany
| | - Ilka Wilhelmi
- German Institute of Human Nutrition, 85764 Potsdam-Rehbrücke, Germany
| | - Marielle E. Yohe
- Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892
| | - Richard A. Kahn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322-3050
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19
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Bhatt JM, Hancock W, Meissner JM, Kaczmarczyk A, Lee E, Viktorova E, Ramanadham S, Belov GA, Sztul E. Promiscuity of the catalytic Sec7 domain within the guanine nucleotide exchange factor GBF1 in ARF activation, Golgi homeostasis, and effector recruitment. Mol Biol Cell 2019; 30:1523-1535. [PMID: 30943106 PMCID: PMC6724685 DOI: 10.1091/mbc.e18-11-0711] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The integrity of the Golgi and trans-Golgi network (TGN) is disrupted by brefeldin A (BFA), which inhibits the Golgi-localized BFA-sensitive factor (GBF1) and brefeldin A-inhibited guanine nucleotide-exchange factors (BIG1 and BIG2). Using a cellular replacement assay to assess GBF1 functionality without interference from the BIGs, we show that GBF1 alone maintains Golgi architecture; facilitates secretion; activates ADP-ribosylation factor (ARF)1, 3, 4, and 5; and recruits ARF effectors to Golgi membranes. Unexpectedly, GBF1 also supports TGN integrity and recruits numerous TGN-localized ARF effectors. The impact of the catalytic Sec7 domain (Sec7d) on GBF1 functionality was assessed by swapping it with the Sec7d from ARF nucleotide-binding site opener (ARNO)/cytohesin-2, a plasma membrane GEF reported to activate all ARFs. The resulting chimera (GBF1-ARNO-GBF1 [GARG]) targets like GBF1, supports Golgi/TGN architecture, and facilitates secretion. However, unlike GBF1, GARG activates all ARFs (including ARF6) at the Golgi/TGN and recruits additional ARF effectors to the Golgi/TGN. Our results have general implications: 1) GEF's targeting is independent of Sec7d, but Sec7d influence the GEF substrate specificity and downstream effector events; 2) all ARFs have access to all membranes, but are restricted in their distribution by the localization of their activating GEFs; and 3) effector association with membranes requires the coincidental presence of activated ARFs and specific membrane identifiers.
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Affiliation(s)
- Jay M Bhatt
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - William Hancock
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Justyna M Meissner
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Aneta Kaczmarczyk
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Eunjoo Lee
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Ekaterina Viktorova
- Department of Veterinary Medicine, Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, MD 20742
| | - Sasanka Ramanadham
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294.,Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL 35294
| | - George A Belov
- Department of Veterinary Medicine, Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, MD 20742
| | - Elizabeth Sztul
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294
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20
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Shin H, Reiner DJ. The Signaling Network Controlling C. elegans Vulval Cell Fate Patterning. J Dev Biol 2018; 6:E30. [PMID: 30544993 PMCID: PMC6316802 DOI: 10.3390/jdb6040030] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 12/08/2018] [Accepted: 12/10/2018] [Indexed: 12/17/2022] Open
Abstract
EGF, emitted by the Anchor Cell, patterns six equipotent C. elegans vulval precursor cells to assume a precise array of three cell fates with high fidelity. A group of core and modulatory signaling cascades forms a signaling network that demonstrates plasticity during the transition from naïve to terminally differentiated cells. In this review, we summarize the history of classical developmental manipulations and molecular genetics experiments that led to our understanding of the signals governing this process, and discuss principles of signal transduction and developmental biology that have emerged from these studies.
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Affiliation(s)
- Hanna Shin
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030, USA.
| | - David J Reiner
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030, USA.
- College of Medicine, Texas A & M University, Houston, TX 77030, USA.
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21
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Saraste J, Marie M. Intermediate compartment (IC): from pre-Golgi vacuoles to a semi-autonomous membrane system. Histochem Cell Biol 2018; 150:407-430. [PMID: 30173361 PMCID: PMC6182704 DOI: 10.1007/s00418-018-1717-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/27/2018] [Indexed: 12/19/2022]
Abstract
Despite its discovery more than three decades ago and well-established role in protein sorting and trafficking in the early secretory pathway, the intermediate compartment (IC) has remained enigmatic. The prevailing view is that the IC evolved as a specialized organelle to mediate long-distance endoplasmic reticulum (ER)–Golgi communication in metazoan cells, but is lacking in other eukaryotes, such as plants and fungi. However, this distinction is difficult to reconcile with the high conservation of the core machineries that regulate early secretory trafficking from yeast to man. Also, it has remained unclear whether the pleiomorphic IC components—vacuoles, tubules and vesicles—represent transient transport carriers or building blocks of a permanent pre-Golgi organelle. Interestingly, recent studies have revealed that the IC maintains its compositional, structural and spatial properties throughout the cell cycle, supporting a model that combines the dynamic and stable aspects of the organelle. Moreover, the IC has been assigned novel functions, such as cell signaling, Golgi-independent trafficking and autophagy. The emerging permanent nature of the IC and its connections with the centrosome and the endocytic recycling system encourage reconsideration of its relationship with the Golgi ribbon, role in Golgi biogenesis and ubiquitous presence in eukaryotic cells.
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Affiliation(s)
- Jaakko Saraste
- Department of Biomedicine and Molecular Imaging Center (MIC), University of Bergen, Jonas Lies vei 91, 5009, Bergen, Norway.
| | - Michaël Marie
- Department of Biomedicine and Molecular Imaging Center (MIC), University of Bergen, Jonas Lies vei 91, 5009, Bergen, Norway
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22
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Luchsinger C, Aguilar M, Burgos PV, Ehrenfeld P, Mardones GA. Functional disruption of the Golgi apparatus protein ARF1 sensitizes MDA-MB-231 breast cancer cells to the antitumor drugs Actinomycin D and Vinblastine through ERK and AKT signaling. PLoS One 2018; 13:e0195401. [PMID: 29614107 PMCID: PMC5882166 DOI: 10.1371/journal.pone.0195401] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Accepted: 03/21/2018] [Indexed: 12/26/2022] Open
Abstract
Increasing evidence indicates that the Golgi apparatus plays active roles in cancer, but a comprehensive understanding of its functions in the oncogenic transformation has not yet emerged. At the same time, the Golgi is becoming well recognized as a hub that integrates its functions of protein and lipid biosynthesis to signal transduction for cell proliferation and migration in cancer cells. Nevertheless, the active function of the Golgi apparatus in cancer cells has not been fully evaluated as a target for combined treatment. Here, we analyzed the effect of perturbing the Golgi apparatus on the sensitivity of the MDA-MB-231 breast cancer cell line to the drugs Actinomycin D and Vinblastine. We disrupted the function of ARF1, a protein necessary for the homeostasis of the Golgi apparatus. We found that the expression of the ARF1-Q71L mutant increased the sensitivity of MDA-MB-231 cells to both Actinomycin D and Vinblastine, resulting in decreased cell proliferation and cell migration, as well as in increased apoptosis. Likewise, the combined treatment of cells with Actinomycin D or Vinblastine and Brefeldin A or Golgicide A, two disrupting agents of the ARF1 function, resulted in similar effects on cell proliferation, cell migration and apoptosis. Interestingly, each combined treatment had distinct effects on ERK1/2 and AKT signaling, as indicated by the decreased levels of either phospho-ERK1/2 or phospho-AKT. Our results suggest that disruption of Golgi function could be used as a strategy for the sensitization of cancer cells to chemotherapy.
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Affiliation(s)
- Charlotte Luchsinger
- Department of Physiology, School of Medicine, Universidad Austral de Chile, Valdivia, Chile
- Center for Interdisciplinary Studies of the Nervous System (CISNe), Universidad Austral de Chile, Valdivia, Chile
| | - Marcelo Aguilar
- Department of Physiology, School of Medicine, Universidad Austral de Chile, Valdivia, Chile
- Center for Interdisciplinary Studies of the Nervous System (CISNe), Universidad Austral de Chile, Valdivia, Chile
| | - Patricia V. Burgos
- Department of Physiology, School of Medicine, Universidad Austral de Chile, Valdivia, Chile
- Center for Interdisciplinary Studies of the Nervous System (CISNe), Universidad Austral de Chile, Valdivia, Chile
- Center for Cell Biology and Biomedicine (CEBICEM), School of Medicine and Science, Universidad San Sebastián, Santiago, Chile
- Center for Aging and Regeneration (CARE), Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Pamela Ehrenfeld
- Center for Interdisciplinary Studies of the Nervous System (CISNe), Universidad Austral de Chile, Valdivia, Chile
- Department of Anatomy, Histology and Pathology, School of Medicine, Universidad Austral de Chile, Valdivia, Chile
| | - Gonzalo A. Mardones
- Department of Physiology, School of Medicine, Universidad Austral de Chile, Valdivia, Chile
- Center for Interdisciplinary Studies of the Nervous System (CISNe), Universidad Austral de Chile, Valdivia, Chile
- Center for Cell Biology and Biomedicine (CEBICEM), School of Medicine and Science, Universidad San Sebastián, Santiago, Chile
- * E-mail:
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23
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Lorenz-Guertin JM, Jacob TC. GABA type a receptor trafficking and the architecture of synaptic inhibition. Dev Neurobiol 2018; 78:238-270. [PMID: 28901728 PMCID: PMC6589839 DOI: 10.1002/dneu.22536] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 09/08/2017] [Accepted: 09/08/2017] [Indexed: 12/21/2022]
Abstract
Ubiquitous expression of GABA type A receptors (GABAA R) in the central nervous system establishes their central role in coordinating most aspects of neural function and development. Dysregulation of GABAergic neurotransmission manifests in a number of human health disorders and conditions that in certain cases can be alleviated by drugs targeting these receptors. Precise changes in the quantity or activity of GABAA Rs localized at the cell surface and at GABAergic postsynaptic sites directly impact the strength of inhibition. The molecular mechanisms constituting receptor trafficking to and from these compartments therefore dictate the efficacy of GABAA R function. Here we review the current understanding of how GABAA Rs traffic through biogenesis, plasma membrane transport, and degradation. Emphasis is placed on discussing novel GABAergic synaptic proteins, receptor and scaffolding post-translational modifications, activity-dependent changes in GABAA R confinement, and neuropeptide and neurosteroid mediated changes. We further highlight modern techniques currently advancing the knowledge of GABAA R trafficking and clinically relevant neurodevelopmental diseases connected to GABAergic dysfunction. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 238-270, 2018.
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Affiliation(s)
- Joshua M Lorenz-Guertin
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15261
| | - Tija C Jacob
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15261
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24
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BIG2-ARF1-RhoA-mDia1 Signaling Regulates Dendritic Golgi Polarization in Hippocampal Neurons. Mol Neurobiol 2018; 55:7701-7716. [PMID: 29455446 DOI: 10.1007/s12035-018-0954-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 02/05/2018] [Indexed: 01/08/2023]
Abstract
Proper dendrite development is essential for establishing neural circuitry, and Rho GTPases play key regulatory roles in this process. From mouse brain lysates, we identified Brefeldin A-inhibited guanine exchange factor 2 (BIG2) as a novel Rho GTPase regulatory protein involved in dendrite growth and maintenance. BIG2 was highly expressed during early development, and knockdown of the ARFGEF2 gene encoding BIG2 significantly reduced total dendrite length and the number of branches. Expression of the constitutively active ADP-ribosylation factor 1 ARF1 Q71L rescued the defective dendrite morphogenesis of ARFGEF2-null neurons, indicating that BIG2 controls dendrite growth and maintenance by activating ARF1. Moreover, BIG2 co-localizes with the Golgi apparatus and is required for Golgi deployment into major dendrites in cultured hippocampal neurons. Simultaneous overexpression of BIG2 and ARF1 activated RhoA, and treatment with the RhoA activator lysophosphatidic acid in neurons lacking BIG2 or ARF1 increased the number of cells with dendritic Golgi, suggesting that BIG2 and ARF1 activate RhoA to promote dendritic Golgi polarization. mDia1 was identified as a downstream effector of BIG2-ARF1-RhoA axis, mediating Golgi polarization and dendritic morphogenesis. Furthermore, in utero electroporation of ARFGEF2 shRNA into the embryonic mouse brain confirmed an in vivo role of BIG2 for Golgi deployment into the apical dendrite. Taken together, our results suggest that BIG2-ARF1-RhoA-mDia1 signaling regulates dendritic Golgi polarization and dendrite growth and maintenance in hippocampal neurons.
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25
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Kaczmarek B, Verbavatz JM, Jackson CL. GBF1 and Arf1 function in vesicular trafficking, lipid homoeostasis and organelle dynamics. Biol Cell 2017; 109:391-399. [PMID: 28985001 DOI: 10.1111/boc.201700042] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/22/2017] [Accepted: 09/25/2017] [Indexed: 01/07/2023]
Abstract
The ADP-ribosylation factor (Arf) small G proteins act as molecular switches to coordinate multiple downstream pathways that regulate membrane dynamics. Their activation is spatially and temporally controlled by the guanine nucleotide exchange factors (GEFs). Members of the evolutionarily conserved GBF/Gea family of Arf GEFs are well known for their roles in formation of coat protein complex I (COPI) vesicles, essential for maintaining the structure and function of the Golgi apparatus. However, studies over the past 10 years have found new functions for these GEFs, along with their substrate Arf1, in lipid droplet metabolism, clathrin-independent endocytosis, signalling at the plasma membrane, mitochondrial dynamics and transport along microtubules. Here, we describe these different functions, focussing in particular on the emerging theme of GFB1 and Arf1 regulation of organelle movement on microtubules.
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Affiliation(s)
- Beata Kaczmarek
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Paris, F-75013, France
| | - Jean-Marc Verbavatz
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Paris, F-75013, France
| | - Catherine L Jackson
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Paris, F-75013, France
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26
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Rafiq NBM, Lieu ZZ, Jiang T, Yu CH, Matsudaira P, Jones GE, Bershadsky AD. Podosome assembly is controlled by the GTPase ARF1 and its nucleotide exchange factor ARNO. J Cell Biol 2016; 216:181-197. [PMID: 28007915 PMCID: PMC5223603 DOI: 10.1083/jcb.201605104] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 09/26/2016] [Accepted: 11/28/2016] [Indexed: 01/07/2023] Open
Abstract
Podosomes represent a class of integrin-mediated cell-matrix adhesions formed by migrating and matrix-degrading cells. We demonstrate that in macrophage-like THP1 cells and fibroblasts stimulated to produce podosomes, down-regulation of the G-protein ARF1 or the ARF1 guanine nucleotide exchange factor, ARNO, by small, interfering RNA or pharmacological inhibitors led to striking podosome elimination. Concomitantly, treatments inducing podosome formation increased the level of guanosine triphosphate (GTP)-bound ARF1. ARNO was found to colocalize with the adhesive rings of podosomes, whereas ARF1 was localized to vesicular structures transiently contacting podosome rings. Inhibition of ARF1 led to an increase in RhoA-GTP levels and triggered assembly of myosin-IIA filaments in THP1 cells, whereas the suppression of myosin-IIA rescued podosome formation regardless of ARF1 inhibition. Finally, expression of constitutively active ARF1 in fibroblasts induced formation of putative podosome precursors: actin-rich puncta coinciding with matrix degradation sites and containing proteins of the podosome core but not of the adhesive ring. Thus, ARNO-ARF1 regulates formation of podosomes by inhibition of RhoA/myosin-II and promotion of actin core assembly.
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Affiliation(s)
- Nisha Bte Mohd Rafiq
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore.,Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, England, UK
| | - Zi Zhao Lieu
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore
| | - Tingting Jiang
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore
| | - Cheng-Han Yu
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore
| | - Paul Matsudaira
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore
| | - Gareth E Jones
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, England, UK
| | - Alexander D Bershadsky
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore .,Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
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27
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Brefeldin A-Inhibited Guanine Nucleotide-Exchange Factor 1 (BIG1) Governs the Recruitment of Tumor Necrosis Factor Receptor-Associated Factor 2 (TRAF2) to Tumor Necrosis Factor Receptor 1 (TNFR1) Signaling Complexes. Int J Mol Sci 2016; 17:ijms17111869. [PMID: 27834853 PMCID: PMC5133869 DOI: 10.3390/ijms17111869] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 10/26/2016] [Accepted: 11/02/2016] [Indexed: 12/02/2022] Open
Abstract
Tumor necrosis factor receptor-associated factor 2 (TRAF2) is a critical mediator of tumor necrosis factor-α (TNF-α) signaling. However, the regulatory mechanisms of TRAF2 are not fully understood. Here we show evidence that TRAF2 requires brefeldin A-inhibited guanine nucleotide-exchange factor 1 (BIG1) to be recruited into TNF receptor 1 (TNFR1) signaling complexes. In BIG1 knockdown cells, TNF-α-induced c-Jun N-terminal kinase (JNK) activation was attenuated and the sensitivity to TNF-α-induced apoptosis was increased. Since these trends correlated well with those of TRAF2 deficient cells as previously demonstrated, we tested whether BIG1 functions as an upstream regulator of TRAF2 in TNFR1 signaling. As expected, we found that knockdown of BIG1 suppressed TNF-α-dependent ubiquitination of TRAF2 that is required for JNK activation, and impaired the recruitment of TRAF2 to the TNFR1 signaling complex (complex I). Moreover, we found that the recruitment of TRAF2 to the death-inducing signaling complex termed complex II was also impaired in BIG1 knockdown cells. These results suggest that BIG1 is a key component of the machinery that drives TRAF2 to the signaling complexes formed after TNFR1 activation. Thus, our data demonstrate a novel and unexpected function of BIG1 that regulates TNFR1 signaling by targeting TRAF2.
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28
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Tanaka Y, Ono N, Shima T, Tanaka G, Katoh Y, Nakayama K, Takatsu H, Shin HW. The phospholipid flippase ATP9A is required for the recycling pathway from the endosomes to the plasma membrane. Mol Biol Cell 2016; 27:3883-3893. [PMID: 27733620 PMCID: PMC5170610 DOI: 10.1091/mbc.e16-08-0586] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 09/30/2016] [Accepted: 10/04/2016] [Indexed: 12/20/2022] Open
Abstract
ATP9A is localized to phosphatidylserine-positive early and recycling endosomes, but not late endosomes, in HeLa cells. ATP9A plays a crucial role in recycling of transferrin and glucose transporter 1 from endosomes to the plasma membrane. Type IV P-type ATPases (P4-ATPases) are phospholipid flippases that translocate phospholipids from the exoplasmic (or luminal) to the cytoplasmic leaflet of lipid bilayers. In Saccharomyces cerevisiae, P4-ATPases are localized to specific subcellular compartments and play roles in compartment-mediated membrane trafficking; however, roles of mammalian P4-ATPases in membrane trafficking are poorly understood. We previously reported that ATP9A, one of 14 human P4-ATPases, is localized to endosomal compartments and the Golgi complex. In this study, we found that ATP9A is localized to phosphatidylserine (PS)-positive early and recycling endosomes, but not late endosomes, in HeLa cells. Depletion of ATP9A delayed the recycling of transferrin from endosomes to the plasma membrane, although it did not affect the morphology of endosomal structures. Moreover, depletion of ATP9A caused accumulation of glucose transporter 1 in endosomes, probably by inhibiting their recycling. By contrast, depletion of ATP9A affected neither the early/late endosomal transport and degradation of epidermal growth factor (EGF) nor the transport of Shiga toxin B fragment from early/recycling endosomes to the Golgi complex. Therefore ATP9A plays a crucial role in recycling from endosomes to the plasma membrane.
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Affiliation(s)
- Yoshiki Tanaka
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Natsuki Ono
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Takahiro Shima
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Gaku Tanaka
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Yohei Katoh
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Kazuhisa Nakayama
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Hiroyuki Takatsu
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Hye-Won Shin
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
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29
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Enhancement of β-catenin activity by BIG1 plus BIG2 via Arf activation and cAMP signals. Proc Natl Acad Sci U S A 2016; 113:5946-51. [PMID: 27162341 DOI: 10.1073/pnas.1601918113] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Multifunctional β-catenin, with critical roles in both cell-cell adhesion and Wnt-signaling pathways, was among HeLa cell proteins coimmunoprecipitated by antibodies against brefeldin A-inhibited guanine nucleotide-exchange factors 1 and 2 (BIG1 or BIG2) that activate ADP-ribosylation factors (Arfs) by accelerating the replacement of bound GDP with GTP. BIG proteins also contain A-kinase anchoring protein (AKAP) sequences that can act as scaffolds for multimolecular assemblies that facilitate and limit cAMP signaling temporally and spatially. Direct interaction of BIG1 N-terminal sequence with β-catenin was confirmed using yeast two-hybrid assays and in vitro synthesized proteins. Depletion of BIG1 and/or BIG2 or overexpression of guanine nucleotide-exchange factor inactive mutant, but not wild-type, proteins interfered with β-catenin trafficking, leading to accumulation at perinuclear Golgi structures. Both phospholipase D activity and vesicular trafficking were required for effects of BIG1 and BIG2 on β-catenin activation. Levels of PKA-phosphorylated β-catenin S675 and β-catenin association with PKA, BIG1, and BIG2 were also diminished after BIG1/BIG2 depletion. Inferring a requirement for BIG1 and/or BIG2 AKAP sequence in PKA modification of β-catenin and its effect on transcription activation, we confirmed dependence of S675 phosphorylation and transcription coactivator function on BIG2 AKAP-C sequence.
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30
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Bhatt JM, Viktorova EG, Busby T, Wyrozumska P, Newman LE, Lin H, Lee E, Wright J, Belov GA, Kahn RA, Sztul E. Oligomerization of the Sec7 domain Arf guanine nucleotide exchange factor GBF1 is dispensable for Golgi localization and function but regulates degradation. Am J Physiol Cell Physiol 2015; 310:C456-69. [PMID: 26718629 DOI: 10.1152/ajpcell.00185.2015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 12/14/2015] [Indexed: 12/15/2022]
Abstract
Members of the large Sec7 domain-containing Arf guanine nucleotide exchange factor (GEF) family have been shown to dimerize through their NH2-terminal dimerization and cyclophilin binding (DCB) and homology upstream of Sec7 (HUS) domains. However, the importance of dimerization in GEF localization and function has not been assessed. We generated a GBF1 mutant (91/130) in which two residues required for oligomerization (K91 and E130 within the DCB domain) were replaced with A and assessed the effects of these mutations on GBF1 localization and cellular functions. We show that 91/130 is compromised in oligomerization but that it targets to the Golgi in a manner indistinguishable from wild-type GBF1 and that it rapidly exchanges between the cytosolic and membrane-bound pools. The 91/130 mutant appears active as it integrates within the functional network at the Golgi, supports Arf activation and COPI recruitment, and sustains Golgi homeostasis and cargo secretion when provided as a sole copy of functional GBF1 in cells. In addition, like wild-type GBF1, the 91/130 mutant supports poliovirus RNA replication, a process requiring GBF1 but believed to be independent of GBF1 catalytic activity. However, oligomerization appears to stabilize GBF1 in cells, and the 91/130 mutant is degraded faster than the wild-type GBF1. Our data support a model in which oligomerization is not a key regulator of GBF1 activity but impacts its function by regulating the cellular levels of GBF1.
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Affiliation(s)
- Jay M Bhatt
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Ekaterina G Viktorova
- Department of Veterinary Medicine, Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, Maryland; and
| | - Theodore Busby
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Paulina Wyrozumska
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Laura E Newman
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia
| | - Helen Lin
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Eunjoo Lee
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
| | - John Wright
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
| | - George A Belov
- Department of Veterinary Medicine, Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, Maryland; and
| | - Richard A Kahn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia
| | - Elizabeth Sztul
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama;
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31
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Regulators and Effectors of Arf GTPases in Neutrophils. J Immunol Res 2015; 2015:235170. [PMID: 26609537 PMCID: PMC4644846 DOI: 10.1155/2015/235170] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 09/30/2015] [Indexed: 12/22/2022] Open
Abstract
Polymorphonuclear neutrophils (PMNs) are key innate immune cells that represent the first line of defence against infection. They are the first leukocytes to migrate from the blood to injured or infected sites. This process involves molecular mechanisms that coordinate cell polarization, delivery of receptors, and activation of integrins at the leading edge of migrating PMNs. These phagocytes actively engulf microorganisms or form neutrophil extracellular traps (NETs) to trap and kill pathogens with bactericidal compounds. Association of the NADPH oxidase complex at the phagosomal membrane for production of reactive oxygen species (ROS) and delivery of proteolytic enzymes into the phagosome initiate pathogen killing and removal. G protein-dependent signalling pathways tightly control PMN functions. In this review, we will focus on the small monomeric GTPases of the Arf family and their guanine exchange factors (GEFs) and GTPase activating proteins (GAPs) as components of signalling cascades regulating PMN responses. GEFs and GAPs are multidomain proteins that control cellular events in time and space through interaction with other proteins and lipids inside the cells. The number of Arf GAPs identified in PMNs is expanding, and dissecting their functions will provide important insights into the role of these proteins in PMN physiology.
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Kuster A, Nola S, Dingli F, Vacca B, Gauchy C, Beaujouan JC, Nunez M, Moncion T, Loew D, Formstecher E, Galli T, Proux-Gillardeaux V. The Q-soluble N-Ethylmaleimide-sensitive Factor Attachment Protein Receptor (Q-SNARE) SNAP-47 Regulates Trafficking of Selected Vesicle-associated Membrane Proteins (VAMPs). J Biol Chem 2015; 290:28056-28069. [PMID: 26359495 DOI: 10.1074/jbc.m115.666362] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Indexed: 11/06/2022] Open
Abstract
SNAREs constitute the core machinery of intracellular membrane fusion, but vesicular SNAREs localize to specific compartments via largely unknown mechanisms. Here, we identified an interaction between VAMP7 and SNAP-47 using a proteomics approach. We found that SNAP-47 mainly localized to cytoplasm, the endoplasmic reticulum (ER), and ERGIC and could also shuttle between the cytoplasm and the nucleus. SNAP-47 preferentially interacted with the trans-Golgi network VAMP4 and post-Golgi VAMP7 and -8. SNAP-47 also interacted with ER and Golgi syntaxin 5 and with syntaxin 1 in the absence of Munc18a, when syntaxin 1 is retained in the ER. A C-terminally truncated SNAP-47 was impaired in interaction with VAMPs and affected their subcellular distribution. SNAP-47 silencing further shifted the subcellular localization of VAMP4 from the Golgi apparatus to the ER. WT and mutant SNAP-47 overexpression impaired VAMP7 exocytic activity. We conclude that SNAP-47 plays a role in the proper localization and function of a subset of VAMPs likely via regulation of their transport through the early secretory pathway.
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Affiliation(s)
- Aurelia Kuster
- Membrane Traffic in Health and Disease, INSERM U950, CNRS, UMR 7592, Institut Jacques Monod, Université Paris Diderot, Sorbonne Paris Cité, F-75013 Paris
| | - Sebastien Nola
- Membrane Traffic in Health and Disease, INSERM U950, CNRS, UMR 7592, Institut Jacques Monod, Université Paris Diderot, Sorbonne Paris Cité, F-75013 Paris
| | - Florent Dingli
- Protein Mass Spectrometry Laboratory, Institut Curie, 75005 Paris
| | - Barbara Vacca
- Membrane Traffic in Health and Disease, INSERM U950, CNRS, UMR 7592, Institut Jacques Monod, Université Paris Diderot, Sorbonne Paris Cité, F-75013 Paris
| | - Christian Gauchy
- Membrane Traffic in Health and Disease, INSERM U950, CNRS, UMR 7592, Institut Jacques Monod, Université Paris Diderot, Sorbonne Paris Cité, F-75013 Paris
| | - Jean-Claude Beaujouan
- Membrane Traffic in Health and Disease, INSERM U950, CNRS, UMR 7592, Institut Jacques Monod, Université Paris Diderot, Sorbonne Paris Cité, F-75013 Paris
| | - Marcela Nunez
- Hybrigenics, 3-5 Impasse Reille, 75014 Paris, France
| | | | - Damarys Loew
- Protein Mass Spectrometry Laboratory, Institut Curie, 75005 Paris
| | | | - Thierry Galli
- Membrane Traffic in Health and Disease, INSERM U950, CNRS, UMR 7592, Institut Jacques Monod, Université Paris Diderot, Sorbonne Paris Cité, F-75013 Paris.
| | - Veronique Proux-Gillardeaux
- Membrane Traffic in Health and Disease, INSERM U950, CNRS, UMR 7592, Institut Jacques Monod, Université Paris Diderot, Sorbonne Paris Cité, F-75013 Paris
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33
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Hanai A, Ohgi M, Yagi C, Ueda T, Shin HW, Nakayama K. Class I Arfs (Arf1 and Arf3) and Arf6 are localized to the Flemming body and play important roles in cytokinesis. J Biochem 2015; 159:201-8. [PMID: 26330566 DOI: 10.1093/jb/mvv088] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 08/10/2015] [Indexed: 11/14/2022] Open
Abstract
Small GTPases play important roles in various aspects of cell division as well as membrane trafficking. We and others previously showed that ADP-ribosylation factor 6 (Arf6) is locally activated around the ingressing cleavage furrow and recruited to the Flemming body in late cytokinesis phases, and involved in faithful completion of cytokinesis. However, knockout of the Arf6 gene or Arf6 depletion by siRNAs did not drastically influence cytokinesis. We here show that, in addition to Arf6, Class I Arfs (Arf1 and Arf3) are localized to the Flemming body, and that double knockdown of Arf1 and Arf3 moderately increases the proportion of multinucleate cells and simultaneous knockdown of Arf1, Arf3 and Arf6 leads to severe cytokinesis defects. These observations indicate that Arf1 and Arf3 as well as Arf6 play important roles in cytokinesis. We further show that EFA6 (exchange factor for Arf6) activates not only Arf6 but also Arf1 in the cell. Taken together with our previous data, these Arf GTPases are likely to be locally activated by EFA6 and in turn targeted to the Flemming body to complete cytokinesis.
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Affiliation(s)
- Ayako Hanai
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Minako Ohgi
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Chikako Yagi
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Tomoko Ueda
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Hye-Won Shin
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Kazuhisa Nakayama
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
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Matsudaira T, Niki T, Taguchi T, Arai H. Transport of the cholera toxin B-subunit from recycling endosomes to the Golgi requires clathrin and AP-1. J Cell Sci 2015; 128:3131-42. [PMID: 26136365 DOI: 10.1242/jcs.172171] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 06/22/2015] [Indexed: 11/20/2022] Open
Abstract
The retrograde pathway is defined by the transport of proteins and lipids from the plasma membrane through endosomes to the Golgi complex, and is essential for a variety of cellular activities. Recycling endosomes are important sorting stations for some retrograde cargo. SMAP2, a GTPase-activating protein (GAP) for Arf1 with a putative clathrin-binding domain, has previously been shown to participate in the retrograde transport of the cholera toxin B-subunit (CTxB) from recycling endosomes. Here, we found that clathrin, a vesicle coat protein, and clathrin adaptor protein complex 1 (AP-1) were present at recycling endosomes and were needed for the retrograde transport of CTxB from recycling endosomes to the Golgi, but not from the plasma membrane to recycling endosomes. SMAP2 immunoprecipitated clathrin and AP-1 through a putative clathrin-binding domain and a CALM-binding domain, and SMAP2 mutants that did not interact with clathrin or AP-1 could not localize to recycling endosomes. Moreover, knockdown of Arf1 suppressed the retrograde transport of CTxB from recycling endosomes to the Golgi. These findings suggest that retrograde transport is mediated by clathrin-coated vesicles from recycling endosomes and that the role of the coat proteins is in the recruitment of Arf GAP to transport vesicles.
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Affiliation(s)
- Tatsuyuki Matsudaira
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Takahiro Niki
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Tomohiko Taguchi
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan Pathological Cell Biology Laboratory, Graduate School of Pharmaceutical Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Hiroyuki Arai
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan Pathological Cell Biology Laboratory, Graduate School of Pharmaceutical Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
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Arst HN, Hernandez-Gonzalez M, Peñalva MA, Pantazopoulou A. GBF/Gea mutant with a single substitution sustains fungal growth in the absence of BIG/Sec7. FEBS Lett 2014; 588:4799-806. [PMID: 25451223 PMCID: PMC4266534 DOI: 10.1016/j.febslet.2014.11.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 11/07/2014] [Accepted: 11/10/2014] [Indexed: 12/11/2022]
Abstract
A. nidulans has a GBF/Gea and a BIG/Sec7 subfamily Golgi Arf1-GEFs, both essential. The late Golgi Arf1-GEF mutant hypB5 conditionally blocks secretion. Residue substitution in the early Golgi Arf1-GEF GeaA suppresses hypB5 and hypBΔ. The mutation alters a GBF/Gea amino acid motif and shifts GeaA localization. GeaA1 alone satisfies the eukaryotic requirement for two Golgi Arf1 GEFs.
Golgi Arf1-guanine nucleotide exchange factors (GEFs) belong to two subfamilies: GBF/Gea and BIG/Sec7. Both are conserved across eukaryotes, but the physiological role of each is not well understood. Aspergillus nidulans has a single member of the early Golgi GBF/Gea-subfamily, geaA, and the late Golgi BIG/Sec7-subfamily, hypB. Both geaA and hypB are essential. hypB5 conditionally blocks secretion. We sought extragenic hypB5 suppressors and obtained geaA1. geaA1 results in Tyr1022Cys within a conserved GBF/Gea-specific S(Y/W/F)(L/I) motif in GeaA. This mutation alters GeaA localization. Remarkably, geaA1 suppresses hypBΔ, indicating that a single mutant Golgi Arf1-GEF suffices for growth.
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Affiliation(s)
- Herbert N Arst
- Section of Microbiology, Department of Medicine, Imperial College London, London SW7 2AZ, United Kingdom; Centro de Investigaciones Biológicas, CSIC, Madrid 28040, Spain
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Skorobogata O, Escobar-Restrepo JM, Rocheleau CE. An AGEF-1/Arf GTPase/AP-1 ensemble antagonizes LET-23 EGFR basolateral localization and signaling during C. elegans vulva induction. PLoS Genet 2014; 10:e1004728. [PMID: 25329472 PMCID: PMC4199573 DOI: 10.1371/journal.pgen.1004728] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2014] [Accepted: 09/02/2014] [Indexed: 02/07/2023] Open
Abstract
LET-23 Epidermal Growth Factor Receptor (EGFR) signaling specifies the vulval cell fates during C. elegans larval development. LET-23 EGFR localization on the basolateral membrane of the vulval precursor cells (VPCs) is required to engage the LIN-3 EGF-like inductive signal. The LIN-2 Cask/LIN-7 Veli/LIN-10 Mint (LIN-2/7/10) complex binds LET-23 EGFR, is required for its basolateral membrane localization, and therefore, vulva induction. Besides the LIN-2/7/10 complex, the trafficking pathways that regulate LET-23 EGFR localization have not been defined. Here we identify vh4, a hypomorphic allele of agef-1, as a strong suppressor of the lin-2 mutant Vulvaless (Vul) phenotype. AGEF-1 is homologous to the mammalian BIG1 and BIG2 Arf GTPase guanine nucleotide exchange factors (GEFs), which regulate secretory traffic between the Trans-Golgi network, endosomes and the plasma membrane via activation of Arf GTPases and recruitment of the AP-1 clathrin adaptor complex. Consistent with a role in trafficking we show that AGEF-1 is required for protein secretion and that AGEF-1 and the AP-1 complex regulate endosome size in coelomocytes. The AP-1 complex has previously been implicated in negative regulation of LET-23 EGFR, however the mechanism was not known. Our genetic data indicate that AGEF-1 is a strong negative regulator of LET-23 EGFR signaling that functions in the VPCs at the level of the receptor. In line with AGEF-1 being an Arf GEF, we identify the ARF-1.2 and ARF-3 GTPases as also negatively regulating signaling. We find that the agef-1(vh4) mutation results in increased LET-23 EGFR on the basolateral membrane in both wild-type and lin-2 mutant animals. Furthermore, unc-101(RNAi), a component of the AP-1 complex, increased LET-23 EGFR on the basolateral membrane in lin-2 and agef-1(vh4); lin-2 mutant animals. Thus, an AGEF-1/Arf GTPase/AP-1 ensemble functions opposite the LIN-2/7/10 complex to antagonize LET-23 EGFR basolateral membrane localization and signaling.
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Affiliation(s)
- Olga Skorobogata
- Division of Endocrinology and Metabolism, Department of Medicine, Research Institute of the McGill University Health Centre, McGill University, Montreal, Quebec, Canada
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
| | | | - Christian E. Rocheleau
- Division of Endocrinology and Metabolism, Department of Medicine, Research Institute of the McGill University Health Centre, McGill University, Montreal, Quebec, Canada
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
- * E-mail:
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Wang J, Du J, Jin Q. Class I ADP-ribosylation factors are involved in enterovirus 71 replication. PLoS One 2014; 9:e99768. [PMID: 24911624 PMCID: PMC4049829 DOI: 10.1371/journal.pone.0099768] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 05/16/2014] [Indexed: 12/16/2022] Open
Abstract
Enterovirus 71 is one of the major causative agents of hand, foot, and mouth disease in infants and children. Replication of enterovirus 71 depends on host cellular factors. The viral replication complex is formed in novel, cytoplasmic, vesicular compartments. It has not been elucidated which cellular pathways are hijacked by the virus to create these vesicles. Here, we investigated whether proteins associated with the cellular secretory pathway were involved in enterovirus 71 replication. We used a loss-of-function assay, based on small interfering RNA. We showed that enterovirus 71 RNA replication was dependent on the activity of Class I ADP-ribosylation factors. Simultaneous depletion of ADP-ribosylation factors 1 and 3, but not three others, inhibited viral replication in cells. We also demonstrated with various techniques that the brefeldin-A-sensitive guanidine nucleotide exchange factor, GBF1, was critically important for enterovirus 71 replication. Our results suggested that enterovirus 71 replication depended on GBF1-mediated activation of Class I ADP-ribosylation factors. These results revealed a connection between enterovirus 71 replication and the cellular secretory pathway; this pathway may represent a novel target for antiviral therapies.
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Affiliation(s)
- Jianmin Wang
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| | - Jiang Du
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
| | - Qi Jin
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China
- * E-mail:
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D'Souza RS, Semus R, Billings EA, Meyer CB, Conger K, Casanova JE. Rab4 orchestrates a small GTPase cascade for recruitment of adaptor proteins to early endosomes. Curr Biol 2014; 24:1187-98. [PMID: 24835460 PMCID: PMC4059052 DOI: 10.1016/j.cub.2014.04.003] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 03/20/2014] [Accepted: 04/01/2014] [Indexed: 12/11/2022]
Abstract
BACKGROUND Early, sorting endosomes are a major crossroad of membrane traffic, at the intersection of the endocytic and exocytic pathways. The sorting of endosomal cargo for delivery to different subcellular destinations is mediated by a number of distinct coat protein complexes, including adaptor protein 1 (AP-1), AP-3, and Golgi-localized, gamma adaptin ear-containing, Arf-binding (GGAs) protein. Ultrastructural studies suggest that these coats assemble onto tubular subdomains of the endosomal membrane, but the mechanisms of coat recruitment and assembly at this site remain poorly understood. RESULTS Here we report that the endosomal Rab protein Rab4 orchestrates a GTPase cascade that results in the sequential recruitment of the ADP-ribosylation factor (Arf)-like protein Arl1; the Arf-specific guanine nucleotide exchange factors BIG1 and BIG2; and the class I Arfs, Arf1 and Arf3. Knockdown of Arf1, or inhibition of BIG1 and BIG2 activity with brefeldin A results in the loss of AP-1, AP-3, and GGA-3, but not Arl1, from endosomal membranes and the formation of elongated tubules. In contrast, depletion of Arl1 randomizes the distribution of Rab4 on endosomal membranes, inhibits the formation of tubular subdomains, and blocks recruitment of BIG1 and BIG2, Arfs, and adaptor protein complexes to the endosome. CONCLUSIONS Together these findings indicate that Arl1 links Rab4-dependent formation of endosomal sorting domains with downstream assembly of adaptor protein complexes that constitute the endosomal sorting machinery.
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Affiliation(s)
- Ryan S D'Souza
- Department of Cell Biology, University of Virginia Health Sciences Centre, P.O. Box 800732, Charlottesville, VA 22908, USA
| | - Rachel Semus
- Department of Cell Biology, University of Virginia Health Sciences Centre, P.O. Box 800732, Charlottesville, VA 22908, USA
| | - Emily A Billings
- Department of Cell Biology, University of Virginia Health Sciences Centre, P.O. Box 800732, Charlottesville, VA 22908, USA
| | - Corey B Meyer
- Department of Cell Biology, University of Virginia Health Sciences Centre, P.O. Box 800732, Charlottesville, VA 22908, USA
| | - Kathryn Conger
- Department of Cell Biology, University of Virginia Health Sciences Centre, P.O. Box 800732, Charlottesville, VA 22908, USA
| | - James E Casanova
- Department of Cell Biology, University of Virginia Health Sciences Centre, P.O. Box 800732, Charlottesville, VA 22908, USA.
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Wittinghofer A. Arf Proteins and Their Regulators: At the Interface Between Membrane Lipids and the Protein Trafficking Machinery. RAS SUPERFAMILY SMALL G PROTEINS: BIOLOGY AND MECHANISMS 2 2014. [PMCID: PMC7123483 DOI: 10.1007/978-3-319-07761-1_8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
The Arf small GTP-binding (G) proteins regulate membrane traffic and organelle structure in eukaryotic cells through a regulated cycle of GTP binding and hydrolysis. The first function identified for Arf proteins was recruitment of cytosolic coat complexes to membranes to mediate vesicle formation. However, subsequent studies have uncovered additional functions, including roles in plasma membrane signalling pathways, cytoskeleton regulation, lipid droplet function, and non-vesicular lipid transport. In contrast to other families of G proteins, there are only a few Arf proteins in each organism, yet they function specifically at many different cellular locations. Part of this specificity is achieved by formation of complexes with their guanine nucleotide-exchange factors (GEFs) and GTPase activating proteins (GAPs) that catalyse GTP binding and hydrolysis, respectively. Because these regulators outnumber their Arf substrates by at least 3-to-1, an important aspect of understanding Arf function is elucidating the mechanisms by which a single Arf protein is incorporated into different GEF, GAP, and effector complexes. New insights into these mechanisms have come from recent studies showing GEF–effector interactions, Arf activation cascades, and positive feedback loops. A unifying theme in the function of Arf proteins, carried out in conjunction with their regulators and effectors, is sensing and modulating the properties of the lipids that make up cellular membranes.
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Affiliation(s)
- Alfred Wittinghofer
- Max-Planck-Institute of Molecular Physiology, Dortmund, Nordrhein-Westfalen Germany
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40
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Torres IL, Rosa-Ferreira C, Munro S. The Arf family G protein Arl1 is required for secretory granule biogenesis in Drosophila. J Cell Sci 2014; 127:2151-60. [PMID: 24610947 DOI: 10.1242/jcs.122028] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The small G protein Arf like 1 (Arl1) is found at the Golgi complex, and its GTP-bound form recruits several effectors to the Golgi including GRIP-domain-containing coiled-coil proteins, and the Arf1 exchange factors Big1 and Big2. To investigate the role of Arl1, we have characterised a loss-of-function mutant of the Drosophila Arl1 orthologue. The gene is essential, and examination of clones of cells lacking Arl1 shows that it is required for recruitment of three of the four GRIP domain golgins to the Golgi, with Drosophila GCC185 being less dependent on Arl1. At a functional level, Arl1 is essential for formation of secretory granules in the larval salivary gland. When Arl1 is missing, Golgi are still present but there is a dispersal of adaptor protein 1 (AP-1), a clathrin adaptor that requires Arf1 for its membrane recruitment and which is known to be required for secretory granule biogenesis. Arl1 does not appear to be required for AP-1 recruitment in all tissues, suggesting that it is crucially required to enhance Arf1 activation at the trans-Golgi in particular tissues.
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Affiliation(s)
- Isabel L Torres
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | | | - Sean Munro
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
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Wyrozumska P, Ashley JW, Ramanadham S, Liu Q, Garvey WT, Sztul E. Novel effects of Brefeldin A (BFA) in signaling through the insulin receptor (IR) pathway and regulating FoxO1-mediated transcription. CELLULAR LOGISTICS 2014; 4:e27732. [PMID: 24843827 PMCID: PMC4022606 DOI: 10.4161/cl.27732] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 01/02/2014] [Accepted: 01/03/2014] [Indexed: 12/19/2022]
Abstract
Brefeldin A (BFA) is a fungal metabolite best known for its ability to inhibit activation of ADP-ribosylation factor (Arf) and thereby inhibit secretory traffic. BFA also appears to regulate the trafficking of the GLUT4 glucose transporter by inducing its relocation from intracellular stores to the cell surface. Such redistribution of GLUT4 is normally regulated by insulin-mediated signaling. Hence, we tested whether BFA may intersect with the insulin pathway. We report that BFA causes the activation of the insulin receptor (IR), IRS-1, Akt-2, and AS160 components of the insulin pathway. The response is mediated through phosphoinositol-3-kinase (PI3K) and Akt kinase since the PI3K inhibitor wortmannin and the Akt inhibitors MK2206 and perifosine inhibit the BFA effect. BFA-mediated activation of the insulin pathway results in Akt-mediated phosphorylation of the insulin-responsive transcription factor FoxO1. This leads to nuclear exclusion of FoxO1 and a decrease in transcription of the insulin-responsive gene SIRT-1. Our findings suggest novel effects for BFA in signaling and transcription, and imply that BFA has multiple intracellular targets and can be used to regulate diverse cellular responses that include vesicular trafficking, signaling and transcription.
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Affiliation(s)
- Paulina Wyrozumska
- Department of Cell, Developmental and Integrative Biology; University of Alabama at Birmingham; Birmingham, AL USA
| | - Jason W Ashley
- Department of Cell, Developmental and Integrative Biology; University of Alabama at Birmingham; Birmingham, AL USA
| | - Sasanka Ramanadham
- Department of Cell, Developmental and Integrative Biology; University of Alabama at Birmingham; Birmingham, AL USA
| | - Qinglan Liu
- Department of Nutrition Sciences University of Alabama at Birmingham; Birmingham, AL USA
| | - W Timothy Garvey
- Department of Nutrition Sciences University of Alabama at Birmingham; Birmingham, AL USA
| | - Elizabeth Sztul
- Department of Cell, Developmental and Integrative Biology; University of Alabama at Birmingham; Birmingham, AL USA
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BIG1, a brefeldin A-inhibited guanine nucleotide-exchange protein regulates neurite development via PI3K–AKT and ERK signaling pathways. Neuroscience 2013; 254:361-8. [DOI: 10.1016/j.neuroscience.2013.09.045] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 09/23/2013] [Accepted: 09/24/2013] [Indexed: 11/20/2022]
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Arf guanine nucleotide-exchange factors BIG1 and BIG2 regulate nonmuscle myosin IIA activity by anchoring myosin phosphatase complex. Proc Natl Acad Sci U S A 2013; 110:E3162-70. [PMID: 23918382 DOI: 10.1073/pnas.1312531110] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Brefeldin A-inhibited guanine nucleotide-exchange factors BIG1 and BIG2 activate, through their Sec7 domains, ADP ribosylation factors (Arfs) by accelerating the replacement of Arf-bound GDP with GTP for initiation of vesicular transport or activation of specific enzymes that modify important phospholipids. They are also implicated in regulation of cell polarization and actin dynamics for directed migration. Reciprocal coimmunoprecipitation of endogenous HeLa cell BIG1 and BIG2 with myosin IIA was demonstrably independent of Arf guanine nucleotide-exchange factor activity, because effects of BIG1 and BIG2 depletion were reversed by overexpression of the cognate BIG molecule C-terminal sequence that follows the Arf activation site. Selective depletion of BIG1 or BIG2 enhanced specific phosphorylation of myosin regulatory light chain (T18/S19) and F-actin content, which impaired cell migration in Transwell assays. Our data are clear evidence of these newly recognized functions for BIG1 and BIG2 in transduction or integration of mechanical signals from integrin adhesions and myosin IIA-dependent actin dynamics. Thus, by anchoring or scaffolding the assembly, organization, and efficient operation of multimolecular myosin phosphatase complexes that include myosin IIA, protein phosphatase 1δ, and myosin phosphatase-targeting subunit 1, BIG1 and BIG2 serve to integrate diverse biophysical and biochemical events in cells.
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Nakai W, Kondo Y, Saitoh A, Naito T, Nakayama K, Shin HW. ARF1 and ARF4 regulate recycling endosomal morphology and retrograde transport from endosomes to the Golgi apparatus. Mol Biol Cell 2013; 24:2570-81. [PMID: 23783033 PMCID: PMC3744953 DOI: 10.1091/mbc.e13-04-0197] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The ARF1+ARF4 and ARF1+ARF3 pairs are both required for integrity of recycling endosomes but are involved in distinct transport pathways: the former pair regulates retrograde transport from endosomes to the TGN, whereas the latter is required for the transferrin recycling pathway from endosomes to the plasma membrane. Small GTPases of the ADP-ribosylation factor (ARF) family, except for ARF6, mainly localize to the Golgi apparatus, where they trigger formation of coated carrier vesicles. We recently showed that class I ARFs (ARF1 and ARF3) localize to recycling endosomes, as well as to the Golgi, and are redundantly required for recycling of endocytosed transferrin. On the other hand, the roles of class II ARFs (ARF4 and ARF5) are not yet fully understood, and the complementary or overlapping functions of class I and class II ARFs have been poorly characterized. In this study, we find that simultaneous depletion of ARF1 and ARF4 induces extensive tubulation of recycling endosomes. Moreover, the depletion of ARF1 and ARF4 inhibits retrograde transport of TGN38 and mannose-6-phosphate receptor from early/recycling endosomes to the trans-Golgi network (TGN) but does not affect the endocytic/recycling pathway of transferrin receptor or inhibit retrograde transport of CD4-furin from late endosomes to the TGN. These observations indicate that the ARF1+ARF4 and ARF1+ARF3 pairs are both required for integrity of recycling endosomes but are involved in distinct transport pathways: the former pair regulates retrograde transport from endosomes to the TGN, whereas the latter is required for the transferrin recycling pathway from endosomes to the plasma membrane.
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Affiliation(s)
- Waka Nakai
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
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Eckler AM, Wilder C, Castanon A, Ferris VM, Lamere RA, Perrin BA, Pearlman R, White B, Byrd C, Ludvik N, Nichols N, Poole-Sumrall K, Sztul E, Styers ML. Haploinsufficiency of the Sec7 guanine nucleotide exchange factor gea1 impairs septation in fission yeast. PLoS One 2013; 8:e56807. [PMID: 23457617 PMCID: PMC3574105 DOI: 10.1371/journal.pone.0056807] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Accepted: 01/15/2013] [Indexed: 11/19/2022] Open
Abstract
Membrane trafficking is essential to eukaryotic life and is controlled by a complex network of proteins that regulate movement of proteins and lipids between organelles. The GBF1/GEA family of Guanine nucleotide Exchange Factors (GEFs) regulates trafficking between the endoplasmic reticulum and Golgi by catalyzing the exchange of GDP for GTP on ADP Ribosylation Factors (Arfs). Activated Arfs recruit coat protein complex 1 (COP-I) to form vesicles that ferry cargo between these organelles. To further explore the function of the GBF1/GEA family, we have characterized a fission yeast mutant lacking one copy of the essential gene gea1 (gea1+/-), the Schizosaccharomyces pombe ortholog of GBF1. The haploinsufficient gea1+/- strain was shown to be sensitive to the GBF1 inhibitor brefeldin A (BFA) and was rescued from BFA sensitivity by gea1p overexpression. No overt defects in localization of arf1p or arf6p were observed in gea1+/- cells, but the fission yeast homolog of the COP-I cargo sac1 was mislocalized, consistent with impaired COP-I trafficking. Although Golgi morphology appeared normal, a slight increase in vacuolar size was observed in the gea1+/- mutant strain. Importantly, gea1+/- cells exhibited dramatic cytokinesis-related defects, including disorganized contractile rings, an increased septation index, and alterations in septum morphology. Septation defects appear to result from altered secretion of enzymes required for septum dynamics, as decreased secretion of eng1p, a β-glucanase required for septum breakdown, was observed in gea1+/- cells, and overexpression of eng1p suppressed the increased septation phenotype. These observations implicate gea1 in regulation of septum breakdown and establish S. pombe as a model system to explore GBF1/GEA function in cytokinesis.
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Affiliation(s)
- Alan M. Eckler
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Caroline Wilder
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Antonio Castanon
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Veronica M. Ferris
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Rachael A. Lamere
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Benjamin A. Perrin
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Ross Pearlman
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Blaise White
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Clifton Byrd
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Nicholas Ludvik
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Nona Nichols
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Kristen Poole-Sumrall
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Elizabeth Sztul
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Melanie L. Styers
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
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Lowery J, Szul T, Styers M, Holloway Z, Oorschot V, Klumperman J, Sztul E. The Sec7 guanine nucleotide exchange factor GBF1 regulates membrane recruitment of BIG1 and BIG2 guanine nucleotide exchange factors to the trans-Golgi network (TGN). J Biol Chem 2013; 288:11532-45. [PMID: 23386609 PMCID: PMC3630886 DOI: 10.1074/jbc.m112.438481] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Three Sec7 guanine nucleotide exchange factors (GEFs) activate ADP-ribosylation factors (ARFs) to facilitate coating of transport vesicles within the secretory and endosomal pathways. GBF1 recruits COPI to pre-Golgi and Golgi compartments, whereas BIG1 and BIG2 recruit AP1 and GGA clathrin adaptors to the trans-Golgi network (TGN) and endosomes. Here, we report a functional cascade between these GEFs by showing that GBF1-activated ARFs (ARF4 and ARF5, but not ARF3) facilitate BIG1 and BIG2 recruitment to the TGN. We localize GBF1 ultrastructurally to the pre-Golgi, the Golgi, and also the TGN. Our findings suggest a model in which GBF1 localized within pre-Golgi and Golgi compartments mediates ARF activation to facilitate recruitment of COPI to membranes, whereas GBF1 localized at the TGN mediates ARF activation that leads to the recruitment of BIG1 and BIG2 to the TGN. Membrane-associated BIG1/2 then activates ARFs that recruit clathrin adaptors. In this cascade, an early acting GEF (GBF1) activates ARFs that mediate recruitment of late acting GEFs (BIG1/2) to coordinate coating events within the pre-Golgi/Golgi/TGN continuum. Such coordination may optimize the efficiency and/or selectivity of cargo trafficking through the compartments of the secretory pathway.
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Affiliation(s)
- Jason Lowery
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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Abstract
The assembly of clathrin/AP (adaptor protein)-1-coated vesicles on the trans-Golgi network and endosomes is much less studied than that of clathrin/AP-2 vesicles at the plasma membrane for endocytosis. In vitro, the association of AP-1 with protein-free liposomes had been shown to require phosphoinositides, Arf1 (ADP-ribosylation factor 1)–GTP and additional cytosolic factor(s). We have purified an active fraction from brain cytosol and found it to contain amphiphysin 1 and 2 and endophilin A1, three proteins known to be involved in the formation of AP-2/clathrin coats at the plasma membrane. Assays with bacterially expressed and purified proteins showed that AP-1 stabilization on liposomes depends on amphiphysin 2 or the amphiphysin 1/2 heterodimer. Activity is independent of the SH3 (Src homology 3) domain, but requires interaction of the WDLW motif with γ-adaptin. Endogenous amphiphysin in neurons and transfected protein in cell lines co-localize perinuclearly with AP-1 at the trans-Golgi network. This localization depends on interaction of clathrin and the adaptor sequence in the amphiphysins and is sensitive to brefeldin A, which inhibits Arf1-dependent AP-1 recruitment. Interaction between AP-1 and amphiphysin 1/2 in vivo was demonstrated by co-immunoprecipitation after cross-linking. These results suggest an involvement of amphiphysins not only with AP-2 at the plasma membrane, but also in AP-1/clathrin coat formation at the trans-Golgi network.
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Martínez-Alonso E, Tomás M, Martínez-Menárguez JA. Morpho-functional architecture of the Golgi complex of neuroendocrine cells. Front Endocrinol (Lausanne) 2013; 4:41. [PMID: 23543640 PMCID: PMC3610015 DOI: 10.3389/fendo.2013.00041] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Accepted: 03/14/2013] [Indexed: 12/22/2022] Open
Abstract
In neuroendocrine cells, prohormones move from the endoplasmic reticulum to the Golgi complex (GC), where they are sorted and packed into secretory granules. The GC is considered the central station of the secretory pathway of proteins and lipids en route to their final destination. In most mammalian cells, it is formed by several stacks of cisternae connected by tubules, forming a continuous ribbon. This organelle shows an extraordinary structural and functional complexity, which is exacerbated by the fact that its architecture is cell type specific and also tuned by the functional status of the cell. It is, indeed, one the most beautiful cellular organelles and, for that reason, perhaps the most extensively photographed by electron microscopists. In recent decades, an exhaustive dissection of the molecular machinery involved in membrane traffic and other Golgi functions has been carried out. Concomitantly, detailed morphological studies have been performed, including 3D analysis by electron tomography, and the precise location of key proteins has been identified by immunoelectron microscopy. Despite all this effort, some basic aspects of Golgi functioning remain unsolved. For instance, the mode of intra-Golgi transport is not known, and two opposing theories (vesicular transport and cisternal maturation models) have polarized the field for many years. Neither of these theories explains all the experimental data so that new theories and combinations thereof have recently been proposed. Moreover, the specific role of the small vesicles and tubules which surround the stacks needs to be clarified. In this review, we summarize our current knowledge of the Golgi architecture in relation with its function and the mechanisms of intra-Golgi transport. Within the same framework, the characteristics of the GC of neuroendocrine cells are analyzed.
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Affiliation(s)
- Emma Martínez-Alonso
- Department of Cell Biology and Histology, Medical School, University of MurciaMurcia, Spain
| | - Mónica Tomás
- Department of Human Anatomy and Embryology, Medical School, Valencia UniversityValencia, Spain
| | - José A. Martínez-Menárguez
- Department of Cell Biology and Histology, Medical School, University of MurciaMurcia, Spain
- *Correspondence: José A. Martínez-Menárguez, Department of Cell Biology and Histology, Medical School, University of Murcia, 30100 Murcia, Spain. e-mail:
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Lin S, Zhou C, Neufeld E, Wang YH, Xu SW, Lu L, Wang Y, Liu ZP, Li D, Li C, Chen S, Le K, Huang H, Liu P, Moss J, Vaughan M, Shen X. BIG1, a brefeldin A-inhibited guanine nucleotide-exchange protein modulates ATP-binding cassette transporter A-1 trafficking and function. Arterioscler Thromb Vasc Biol 2012; 33:e31-8. [PMID: 23220274 DOI: 10.1161/atvbaha.112.300720] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECTIVE Cell-surface localization and intracellular trafficking are essential for the function of ATP-binding cassette transporter A-1 (ABCA1). However, regulation of these activities is still largely unknown. Brefeldin A, an uncompetitive inhibitor of brefeldin A-inhibited guanine nucleotide-exchange proteins (BIGs), disturbs the intracellular distribution of ABCA1, and thus inhibits cholesterol efflux. This study aimed to define the possible roles of BIGs in regulating ABCA1 trafficking and cholesterol efflux, and further to explore the potential mechanism. METHODS AND RESULTS By vesicle immunoprecipitation, we found that BIG1 was associated with ABCA1 in vesicles preparation from rat liver. BIG1 depletion reduced surface ABCA1 on HepG2 cells, and inhibited by 60% cholesterol release. In contrast, BIG1 overexpression increased surface ABCA1 and cholesterol secretion. With partial restoration of BIG1 through overexpression in BIG1-depleted cells, surface ABCA1 was also restored. Biotinylation and glutathione cleavage revealed that BIG1 small interfering RNA dramatically decreased the internalization and recycling of ABCA1. This novel function of BIG1 was dependent on the guanine nucleotide-exchange activity and achieved through activation of ADP-ribosylation factor 1. CONCLUSIONS BIG1, through its ability to activate ADP-ribosylation factor 1, regulates cell-surface levels and function of ABCA1, indicating a transcription-independent mechanism for controlling ABCA1 action.
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Affiliation(s)
- Sisi Lin
- Laboratory of Pharmacology and Toxicology, School of Pharmaceutical Sciences, Sun Yat-sen University, No. 132, East Wai-Huan Rd, College Town, Guangzhou 510006, PR China
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50
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Kondo Y, Hanai A, Nakai W, Katoh Y, Nakayama K, Shin HW. ARF1 and ARF3 are required for the integrity of recycling endosomes and the recycling pathway. Cell Struct Funct 2012; 37:141-54. [PMID: 22971977 DOI: 10.1247/csf.12015] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Small GTPases ARF1 and ARF3 localize mainly to the Golgi apparatus, where they trigger formation of coated carrier vesicles. We previously showed that BIG2, a guanine nucleotide exchange factor specific for ARF1 and ARF3, localizes not only to the trans-Golgi network (TGN) but also to recycling endosomes, where it is involved in regulating the integrity of recycling endosomes. However, it is not yet clear whether ARF1 and ARF3 act downstream of BIG2 to ensure endosome integrity. In this study, we show that EGFP-tagged ARF1 and ARF3 localize to endosomal compartments containing endocytosed transferrin. We further demonstrate that simultaneous depletion of ARF1 and ARF3 induces tubulation of recycling endosomal compartments positive for transferrin receptor, Rab4, and Rab11, but does not significantly affect the integrity of the Golgi apparatus or early or late endosomes. Moreover, the simultaneous depletion of ARF1 and ARF3 suppresses recycling of transferrin but does not affect either its endocytosis or the retrograde transport of TGN38 from early/recycling endosomes to the TGN. In addition, depletion of ARF1 and ARF3 does not affect retrograde transport of CD4-furin from late endosomes to the TGN, or of endocytosed EGF from late endosomes to lysosomes. These results indicate that ARF1 and ARF3 are redundantly required for the integrity of recycling endosomes, and that they regulate transferrin recycling from endosomes to the plasma membrane, but not retrograde transport from endosomal compartments to the TGN.
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Affiliation(s)
- Yumika Kondo
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
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