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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 PMCID: PMC11264237 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] [Grants] [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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Hirano J, Hayashi T, Kitamura K, Nishimura Y, Shimizu H, Okamoto T, Okada K, Uemura K, Yeh MT, Ono C, Taguwa S, Muramatsu M, Matsuura Y. Enterovirus 3A protein disrupts endoplasmic reticulum homeostasis through interaction with GBF1. J Virol 2024; 98:e0081324. [PMID: 38904364 PMCID: PMC11265424 DOI: 10.1128/jvi.00813-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2024] [Accepted: 05/10/2024] [Indexed: 06/22/2024] Open
Abstract
Enteroviruses are single-stranded, positive-sense RNA viruses causing endoplasmic reticulum (ER) stress to induce or modulate downstream signaling pathways known as the unfolded protein responses (UPR). However, viral and host factors involved in the UPR related to viral pathogenesis remain unclear. In the present study, we aimed to identify the major regulator of enterovirus-induced UPR and elucidate the underlying molecular mechanisms. We showed that host Golgi-specific brefeldin A-resistant guanine nucleotide exchange factor 1 (GBF1), which supports enteroviruses replication, was a major regulator of the UPR caused by infection with enteroviruses. In addition, we found that severe UPR was induced by the expression of 3A proteins encoded in human pathogenic enteroviruses, such as enterovirus A71, coxsackievirus B3, poliovirus, and enterovirus D68. The N-terminal-conserved residues of 3A protein interact with the GBF1 and induce UPR through inhibition of ADP-ribosylation factor 1 (ARF1) activation via GBF1 sequestration. Remodeling and expansion of ER and accumulation of ER-resident proteins were observed in cells infected with enteroviruses. Finally, 3A induced apoptosis in cells infected with enteroviruses via activation of the protein kinase RNA-like endoplasmic reticulum kinase (PERK)/C/EBP homologous protein (CHOP) pathway of UPR. Pharmaceutical inhibition of PERK suppressed the cell death caused by infection with enteroviruses, suggesting the UPR pathway is a therapeutic target for treating diseases caused by infection with enteroviruses.IMPORTANCEInfection caused by several plus-stranded RNA viruses leads to dysregulated ER homeostasis in the host cells. The mechanisms underlying the disruption and impairment of ER homeostasis and its significance in pathogenesis upon enteroviral infection remain unclear. Our findings suggested that the 3A protein encoded in human pathogenic enteroviruses disrupts ER homeostasis by interacting with GBF1, a major regulator of UPR. Enterovirus-mediated infections drive ER into pathogenic conditions, where ER-resident proteins are accumulated. Furthermore, in such scenarios, the PERK/CHOP signaling pathway induced by an unresolved imbalance of ER homeostasis essentially drives apoptosis. Therefore, elucidating the mechanisms underlying the virus-induced disruption of ER homeostasis might be a potential target to mitigate the pathogenesis of enteroviruses.
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Affiliation(s)
- Junki Hirano
- Laboratory of Virus Control, Center for Infectious Disease Education and Research (CiDER), Osaka, Japan
- Research Institute for Microbial Diseases (RIMD), Osaka University, Osaka, Japan
- Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - Tsuyoshi Hayashi
- Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - Kouichi Kitamura
- Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - Yorihiro Nishimura
- Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - Hiroyuki Shimizu
- Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - Toru Okamoto
- Institute for Advanced Co-Creation Studies, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
- Department of Microbiology, Juntendo University School of Medicine, Tokyo, Japan
| | - Kazuma Okada
- Laboratory of Virus Control, Center for Infectious Disease Education and Research (CiDER), Osaka, Japan
- Research Institute for Microbial Diseases (RIMD), Osaka University, Osaka, Japan
| | - Kentaro Uemura
- Laboratory of Virus Control, Center for Infectious Disease Education and Research (CiDER), Osaka, Japan
- Research Institute for Microbial Diseases (RIMD), Osaka University, Osaka, Japan
| | - Ming Te Yeh
- Research Institute for Microbial Diseases (RIMD), Osaka University, Osaka, Japan
- Center for Advanced Modalities and DDS (CAMaD), Osaka University, Osaka, Japan
| | - Chikako Ono
- Laboratory of Virus Control, Center for Infectious Disease Education and Research (CiDER), Osaka, Japan
- Research Institute for Microbial Diseases (RIMD), Osaka University, Osaka, Japan
| | - Shuhei Taguwa
- Laboratory of Virus Control, Center for Infectious Disease Education and Research (CiDER), Osaka, Japan
- Research Institute for Microbial Diseases (RIMD), Osaka University, Osaka, Japan
- Center for Advanced Modalities and DDS (CAMaD), Osaka University, Osaka, Japan
| | - Masamichi Muramatsu
- Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan
- Department of Infectious Disease Research, Institute of Biomedical Research and Innovation, Foundation for Biomedical Research and Innovation at Kobe, Kobe, Japan
| | - Yoshiharu Matsuura
- Laboratory of Virus Control, Center for Infectious Disease Education and Research (CiDER), Osaka, Japan
- Research Institute for Microbial Diseases (RIMD), Osaka University, Osaka, Japan
- Center for Advanced Modalities and DDS (CAMaD), Osaka University, Osaka, Japan
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Rabino A, Awadia S, Ali N, Edson A, Garcia-Mata R. The Scribble/SGEF/Dlg1 complex regulates the stability of apical junctions in epithelial cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.26.586884. [PMID: 38585765 PMCID: PMC10996629 DOI: 10.1101/2024.03.26.586884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
SGEF, a RhoG specific GEF, can form a ternary complex with the Scribble polarity complex proteins Scribble and Dlg1, which regulates the formation and maintenance of adherens junctions and barrier function of epithelial cells. Notably, silencing SGEF results in a dramatic downregulation of the expression of both E-cadherin and ZO-1. However, the molecular mechanisms involved in the regulation of this pathway are not known. Here, we describe a novel signaling pathway governed by the Scribble/SGEF/Dlg1 complex. Our results show that an intact ternary complex is required to maintain the stability of the apical junctions, the expression of ZO-1, and TJ permeability. In contrast, only SGEF is necessary to regulate E-cadherin expression. The absence of SGEF destabilizes the E-cadherin/catenin complex at the membrane, triggering a positive feedback loop that exacerbates the phenotype through the repression of E-cadherin transcription in a process that involves the internalization of E-cadherin by endocytosis, β-catenin signaling and the transcriptional repressor Slug.
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Affiliation(s)
- Agustin Rabino
- Department of Biological Sciences, University of Toledo, Toledo, OH, USA
| | - Sahezeel Awadia
- Department of Biological Sciences, University of Toledo, Toledo, OH, USA
| | - Nabaa Ali
- Department of Biological Sciences, University of Toledo, Toledo, OH, USA
| | - Amber Edson
- Department of Biological Sciences, University of Toledo, Toledo, OH, USA
| | - Rafael Garcia-Mata
- Department of Biological Sciences, University of Toledo, Toledo, OH, USA
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Meissner JM, Akhmetova K, Szul T, Viktorova EG, Sha B, Bhatt JM, Lee EJ, Kahn RA, Belov GA, Chesnokov I, Sztul E. The Arf-GEF GBF1 undergoes multi-domain structural shifts to activate Arf at the Golgi. Front Cell Dev Biol 2023; 11:1233272. [PMID: 37745300 PMCID: PMC10512945 DOI: 10.3389/fcell.2023.1233272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 08/29/2023] [Indexed: 09/26/2023] Open
Abstract
Golgi homeostasis require the activation of Arf GTPases by the guanine-nucleotide exchange factor requires GBF1, whose recruitment to the Golgi represents a rate limiting step in the process. GBF1 contains a conserved, catalytic, Sec7 domain (Sec7d) and five additional (DCB, HUS, HDS1-3) domains. Herein, we identify the HDS3 domain as essential for GBF1 membrane association in mammalian cells and document the critical role of HDS3 during the development of Drosophila melanogaster. We show that upon binding to Golgi membranes, GBF1 undergoes conformational changes in regions bracketing the catalytic Sec7d. We illuminate GBF1 interdomain arrangements by negative staining electron microscopy of full-length human GBF1 to show that GBF1 forms an anti-parallel dimer held together by the paired central DCB-HUS core, with two sets of HDS1-3 arms extending outward in opposite directions. The catalytic Sec7d protrudes from the central core as a largely independent domain, but is closely opposed to a previously unassigned α-helix from the HDS1 domain. Based on our data, we propose models of GBF1 engagement on the membrane to provide a paradigm for understanding GBF1-mediated Arf activation required for cellular and organismal function.
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Affiliation(s)
- Justyna M. Meissner
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Katarina Akhmetova
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Tomasz Szul
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Ekaterina G. Viktorova
- Department of Veterinary Medicine, Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, MD, United States
| | - Bingdong Sha
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Jay M. Bhatt
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Eunjoo J. Lee
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Richard A. Kahn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, United States
| | - George A. Belov
- Department of Veterinary Medicine, Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, MD, United States
| | - Igor Chesnokov
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Elizabeth Sztul
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, United States
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5
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Walton K, Nawara TJ, Angermeier AR, Rosengrant H, Lee E, Wynn B, Victorova E, Belov G, Sztul E. Site-specific phosphorylations of the Arf activator GBF1 differentially regulate GBF1 function in Golgi homeostasis and secretion versus cytokinesis. Sci Rep 2023; 13:13609. [PMID: 37604968 PMCID: PMC10442430 DOI: 10.1038/s41598-023-40705-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 08/16/2023] [Indexed: 08/23/2023] Open
Abstract
Diverse cellular processes, including membrane traffic, lipid homeostasis, cytokinesis, mitochondrial positioning, and cell motility are critically dependent on the Sec7 domain guanine nucleotide exchange factor GBF1. Yet, how the participation of GBF1 in a particular cellular function is regulated is unknown. Here, we show that the phosphorylation of specific highly conserved serine and tyrosine residues within the N-terminal domain of GBF1 differentially regulates its function in maintaining Golgi homeostasis and facilitating secretion versus its role in cytokinesis. Specifically, GBF1 mutants containing single amino acid substitutions that mimic a stably phosphorylated S233, S371, Y377, and Y515 or the S233A mutant that can't be phosphorylated are fully able to maintain Golgi architecture and support cargo traffic through the secretory pathway when assessed in multiple functional assays. However, the same mutants cause multi-nucleation when expressed in cells, and appear to inhibit the progression through mitosis and the resolution of cytokinetic bridges. Thus, GBF1 participates in distinct interactive networks when mediating Golgi homeostasis and secretion versus facilitating cytokinesis, and GBF1 integration into such networks is differentially regulated by the phosphorylation of specific GBF1 residues.
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Affiliation(s)
- Kendall Walton
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 668, Birmingham, AL, 35233-2008, USA.
| | - Tomasz J Nawara
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 668, Birmingham, AL, 35233-2008, USA
| | - Allyson R Angermeier
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 668, Birmingham, AL, 35233-2008, USA
| | - Hadley Rosengrant
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 668, Birmingham, AL, 35233-2008, USA
| | - Eunjoo Lee
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 668, Birmingham, AL, 35233-2008, USA
| | - Bridge Wynn
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 668, Birmingham, AL, 35233-2008, USA
| | - Ekaterina Victorova
- Department of Veterinary Medicine, Virginia-Maryland College of Veterinary Medicine, University of Maryland, College Park, MD, 20742, USA
| | - George Belov
- Department of Veterinary Medicine, Virginia-Maryland College of Veterinary Medicine, University of Maryland, College Park, MD, 20742, USA
| | - Elizabeth Sztul
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 668, Birmingham, AL, 35233-2008, USA
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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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Khakurel A, Kudlyk T, Pokrovskaya I, D’Souza Z, Lupashin VV. GARP dysfunction results in COPI displacement, depletion of Golgi v-SNAREs and calcium homeostasis proteins. Front Cell Dev Biol 2022; 10:1066504. [PMID: 36578782 PMCID: PMC9791199 DOI: 10.3389/fcell.2022.1066504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 11/30/2022] [Indexed: 12/14/2022] Open
Abstract
Golgi-associated retrograde protein (GARP) is an evolutionary conserved heterotetrameric protein complex that tethers endosome-derived vesicles and is vital for Golgi glycosylation. Microscopy and proteomic approaches were employed to investigate defects in Golgi physiology in RPE1 cells depleted for the GARP complex. Both cis and trans-Golgi compartments were significantly enlarged in GARP-knock-out (KO) cells. Proteomic analysis of Golgi-enriched membranes revealed significant depletion of a subset of Golgi residents, including Ca2+ binding proteins, enzymes, and SNAREs. Validation of proteomics studies revealed that SDF4 and ATP2C1, related to Golgi calcium homeostasis, as well as intra-Golgi v-SNAREs GOSR1 and BET1L, were significantly depleted in GARP-KO cells. Finding that GARP-KO is more deleterious to Golgi physiology than deletion of GARP-sensitive v-SNAREs, prompted a detailed investigation of COPI trafficking machinery. We discovered that in GARP-KO cells COPI is significantly displaced from the Golgi and partially relocalized to the ER-Golgi intermediate compartment (ERGIC). Moreover, COPI accessory proteins GOLPH3, ARFGAP1, GBF1, and BIG1 are also relocated to off-Golgi compartments. We propose that the dysregulation of COPI machinery, along with the depletion of Golgi v-SNAREs and alteration of Golgi Ca2+ homeostasis, are the major driving factors for the depletion of Golgi resident proteins, structural alterations, and glycosylation defects in GARP deficient cells.
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Jiang L, Zhang T, Lu K, Qi S. The progress in C9orf72 research: ALS/FTD pathogenesis, functions and structure. Small GTPases 2022; 13:56-76. [PMID: 33663328 PMCID: PMC9707547 DOI: 10.1080/21541248.2021.1892443] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The hexanucleotide repeat (GGGGCC) expansion in C9orf72 is accounted for a large proportion of the genetic amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). The hypotheses of how the massive G4C2 repeats in C9orf72 destroy the neurons and lead to ALS/FTD are raised and improving. As a multirole player, C9orf72 exerts critical roles in many cellular processes, including autophagy, membrane trafficking, immune response, and so on. Notably, the partners of C9orf72, through which C9orf72 participates in the cell activities, have been identified. Notably, the structures of the C9orf72-SMCR8-WDR41 complex shed light on its activity as GTPase activating proteins (GAP). In this manuscript, we reviewed the latest research progress in the C9orf72-mediated ALS/FTD, the physiological functions of C9orf72, and the putative function models of C9orf72/C9orf72-containing complex.
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Affiliation(s)
- Lan Jiang
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, Chengdu, China
| | - Tizhong Zhang
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, Chengdu, China
| | - Kefeng Lu
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, Chengdu, China
| | - Shiqian Qi
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, Chengdu, China,CONTACT Shiqian Qi Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, Chengdu, China.
These authors contributed equally to this work.
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9
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Zou YJ, Shan MM, Pan ZN, Pan MH, Li XH, Sun SC. Loss of Arf Guanine Nucleotide Exchange Factor GBF1 Activity Disturbs Organelle Dynamics in Mouse Oocytes. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2021; 27:400-408. [PMID: 33478608 DOI: 10.1017/s1431927620024885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
GBF1 [Golgi brefeldin A (BFA) resistance factor 1] is a member of the guanine nucleotide exchange factors Arf family. GBF1 localizes at the cis-Golgi and endoplasmic reticulum (ER)-Golgi intermediate compartment where it participates in ER-Golgi traffic by assisting in the recruitment of the coat protein COPI. However, the roles of GBF1 in oocyte meiotic maturation are still unknown. In the present study, we investigated the regulatory functions of GBF1 in mouse oocyte organelle dynamics. In our results, GBF1 was stably expressed during oocyte maturation, and GBF1 localized at the spindle periphery during metaphase I. Inhibiting GBF1 activity led to aberrant accumulation of the Golgi apparatus around the spindle. This may be due to the effects of GBF1 on the localization of GM130, as GBF1 co-localized with GM130 and inhibiting GBF1 induced condensation of GM130. Moreover, the loss of GBF1 activity affected the ER distribution and induced ER stress, as shown by increased GRP78 expression. Mitochondrial localization and functions were affected, as the mitochondrial membrane potential was altered. Taken together, these results suggest that GBF1 has wide-ranging effects on the distribution and functions of Golgi apparatus, ER, and mitochondria as well as normal polar body formation in mouse oocytes.
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Affiliation(s)
- Yuan-Jing Zou
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing210095, China
| | - Meng-Meng Shan
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing210095, China
| | - Zhen-Nan Pan
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing210095, China
| | - Meng-Hao Pan
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing210095, China
| | - Xiao-Han Li
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing210095, China
| | - Shao-Chen Sun
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing210095, China
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Sager G, Szul T, Lee E, Kawai R, Presley JF, Sztul E. Modeling the dynamic behaviors of the COPI vesicle formation regulators, the small GTPase Arf1 and its activating Sec7 guanine nucleotide exchange factor GBF1 on Golgi membranes. Mol Biol Cell 2021; 32:446-459. [PMID: 33405949 PMCID: PMC8098855 DOI: 10.1091/mbc.e20-09-0587] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The components and subprocesses underlying the formation of COPI-coated vesicles at the Golgi are well understood. The coating cascade is initiated after the small GTPase Arf1 is activated by the Sec7 domain–containing guanine nucleotide exchange factor GBF1 (Golgi brefeldin A resistant guanine nucleotide exchange factor 1). This causes a conformational shift within Arf1 that facilitates stable association of Arf1 with the membrane, a process required for subsequent recruitment of the COPI coat. Although we have atomic-level knowledge of Arf1 activation by Sec7 domain–containing GEFs, our understanding of the biophysical processes regulating Arf1 and GBF1 dynamics is limited. We used fluorescence recovery after photobleaching data and kinetic Monte Carlo simulation to assess the behavior of Arf1 and GBF1 during COPI vesicle formation in live cells. Our analyses suggest that Arf1 and GBF1 associate with Golgi membranes independently, with an excess of GBF1 relative to Arf1. Furthermore, the GBF1-mediated Arf1 activation is much faster than GBF1 cycling on/off the membrane, suggesting that GBF1 is regulated by processes other than its interactions Arf1. Interestingly, modeling the behavior of the catalytically inactive GBF1/E794K mutant stabilized on the membrane is inconsistent with the formation of a stable complex between it and an endogenous Arf1 and suggests that GBF1/E794K is stabilized on the membrane independently of complex formation.
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Affiliation(s)
- Garrett Sager
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35924.,Department of Physics, University of Alabama at Birmingham, Birmingham, AL 35924
| | - Tomasz Szul
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35924
| | - Eunjoo Lee
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35924
| | - Ryoichi Kawai
- Department of Physics, University of Alabama at Birmingham, Birmingham, AL 35924
| | - John F Presley
- Department of Anatomy & Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada
| | - Elizabeth Sztul
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35924
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11
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Deretic D, Lorentzen E, Fresquez T. The ins and outs of the Arf4-based ciliary membrane-targeting complex. Small GTPases 2021; 12:1-12. [PMID: 31068062 PMCID: PMC7781591 DOI: 10.1080/21541248.2019.1616355] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 04/09/2019] [Accepted: 05/02/2019] [Indexed: 10/26/2022] Open
Abstract
The small GTPase Arf4-based ciliary membrane-targeting complex recognizes specific targeting signals within sensory receptors and regulates their directed movement to primary cilia. Activated Arf4 directly binds the VxPx ciliary-targeting signal (CTS) of the light-sensing receptor rhodopsin. Recent findings revealed that at the trans-Golgi, marked by the small GTPase Rab6, activated Arf4 forms a functional complex with rhodopsin and the Arf guanine nucleotide exchange factor (GEF) GBF1, providing positive feedback that drives further Arf4 activation in ciliary trafficking. Arf4 function is conserved across diverse cell types; however, it appears that not all its aspects are conserved across species, as mouse Arf4 is a natural mutant in the conserved α3 helix, which is essential for its interaction with rhodopsin. Generally, activated Arf4 regulates the assembly of the targeting nexus containing the Arf GAP ASAP1 and the Rab11a-FIP3-Rabin8 dual effector complex, which controls the assembly of the highly conserved Rab11a-Rabin8-Rab8 ciliary-targeting module. It was recently found that this module interacts with the R-SNARE VAMP7, likely in its activated, c-Src-phosphorylated form. Rab11 and Rab8 bind VAMP7 regulatory longin domain (LD), whereas Rabin8 interacts with the SNARE domain, capturing VAMP7 for delivery to the ciliary base and subsequent pairing with the cognate SNAREs syntaxin 3 and SNAP-25. This review will focus on the implications of these novel findings that further illuminate the role of well-ordered Arf and Rab interaction networks in targeting of sensory receptors to primary cilia. Abbreviations: CTS: Ciliary-Targeting Signal; GAP: GTPase Activating Protein; GEF: Guanine Nucleotide Exchange Factor; RTC(s), Rhodopsin Transport Carrier(s); SNARE: Soluble N-ethylmaleimide-sensitive Factor Attachment Protein Receptor; TGN: Trans-Golgi Network.
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Affiliation(s)
- Dusanka Deretic
- Departments of Surgery, Division of Ophthalmology, University of New Mexico, Albuquerque, NM, USA
- Cell Biology and Physiology, University of New Mexico, Albuquerque, NM, USA
| | - Esben Lorentzen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Theresa Fresquez
- Departments of Surgery, Division of Ophthalmology, University of New Mexico, Albuquerque, NM, USA
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12
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Mendoza-Ferreira N, Karakaya M, Cengiz N, Beijer D, Brigatti KW, Gonzaga-Jauregui C, Fuhrmann N, Hölker I, Thelen MP, Zetzsche S, Rombo R, Puffenberger EG, De Jonghe P, Deconinck T, Zuchner S, Strauss KA, Carson V, Schrank B, Wunderlich G, Baets J, Wirth B. De Novo and Inherited Variants in GBF1 are Associated with Axonal Neuropathy Caused by Golgi Fragmentation. Am J Hum Genet 2020; 107:763-777. [PMID: 32937143 PMCID: PMC7491385 DOI: 10.1016/j.ajhg.2020.08.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 08/19/2020] [Indexed: 01/18/2023] Open
Abstract
Distal hereditary motor neuropathies (HMNs) and axonal Charcot-Marie-Tooth neuropathy (CMT2) are clinically and genetically heterogeneous diseases characterized primarily by motor neuron degeneration and distal weakness. The genetic cause for about half of the individuals affected by HMN/CMT2 remains unknown. Here, we report the identification of pathogenic variants in GBF1 (Golgi brefeldin A-resistant guanine nucleotide exchange factor 1) in four unrelated families with individuals affected by sporadic or dominant HMN/CMT2. Genomic sequencing analyses in seven affected individuals uncovered four distinct heterozygous GBF1 variants, two of which occurred de novo. Other known HMN/CMT2-implicated genes were excluded. Affected individuals show HMN/CMT2 with slowly progressive distal muscle weakness and musculoskeletal deformities. Electrophysiological studies confirmed axonal damage with chronic neurogenic changes. Three individuals had additional distal sensory loss. GBF1 encodes a guanine-nucleotide exchange factor that facilitates the activation of members of the ARF (ADP-ribosylation factor) family of small GTPases. GBF1 is mainly involved in the formation of coatomer protein complex (COPI) vesicles, maintenance and function of the Golgi apparatus, and mitochondria migration and positioning. We demonstrate that GBF1 is present in mouse spinal cord and muscle tissues and is particularly abundant in neuropathologically relevant sites, such as the motor neuron and the growth cone. Consistent with the described role of GBF1 in Golgi function and maintenance, we observed marked increase in Golgi fragmentation in primary fibroblasts derived from all affected individuals in this study. Our results not only reinforce the existing link between Golgi fragmentation and neurodegeneration but also demonstrate that pathogenic variants in GBF1 are associated with HMN/CMT2.
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13
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Gonçalves-Pimentel C, Mazaud D, Kottler B, Proelss S, Hirth F, Fanto M. A miRNA screen procedure identifies garz as an essential factor in adult glia functions and validates Drosophila as a beneficial 3Rs model to study glial functions and GBF1 biology. F1000Res 2020; 9:317. [PMID: 32595956 PMCID: PMC7309417 DOI: 10.12688/f1000research.23154.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/21/2020] [Indexed: 03/21/2024] Open
Abstract
Invertebrate glia performs most of the key functions controlled by mammalian glia in the nervous system and provides an ideal model for genetic studies of glial functions. To study the influence of adult glial cells in ageing we have performed a genetic screen in Drosophila using a collection of transgenic lines providing conditional expression of micro-RNAs (miRNAs). Here, we describe a methodological algorithm to identify and rank genes that are candidate to be targeted by miRNAs that shorten lifespan when expressed in adult glia. We have used four different databases for miRNA target prediction in Drosophila but find little agreement between them, overall. However, top candidate gene analysis shows potential to identify essential genes involved in adult glial functions. One example from our top candidates' analysis is gartenzwerg ( garz). We establish that garz is necessary in many glial cell types, that it affects motor behaviour and, at the sub-cellular level, is responsible for defects in cellular membranes, autophagy and mitochondria quality control. We also verify the remarkable conservation of functions between garz and its mammalian orthologue, GBF1, validating the use of Drosophila as an alternative 3Rs-beneficial model to knock-out mice for studying the biology of GBF1, potentially involved in human neurodegenerative diseases.
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Affiliation(s)
- Catarina Gonçalves-Pimentel
- Department of Basic and Clinical Neuroscience, King's College London, London, SE5 9NU, UK
- Champalimaud Research, Champalimaud Foundation, Av. Brasília, Lisbon, 1400-038, Portugal
| | - David Mazaud
- Department of Basic and Clinical Neuroscience, King's College London, London, SE5 9NU, UK
| | - Benjamin Kottler
- Department of Basic and Clinical Neuroscience, King's College London, London, SE5 9NU, UK
| | - Sandra Proelss
- Department of Basic and Clinical Neuroscience, King's College London, London, SE5 9NU, UK
| | - Frank Hirth
- Department of Basic and Clinical Neuroscience, King's College London, London, SE5 9NU, UK
| | - Manolis Fanto
- Department of Basic and Clinical Neuroscience, King's College London, London, SE5 9NU, UK
- Institut du Cerveau et de la Moelle épinière (ICM), 47, bd de l'hôpital, Paris, F-75013, France
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14
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Gonçalves-Pimentel C, Mazaud D, Kottler B, Proelss S, Hirth F, Fanto M. A miRNA screen procedure identifies garz as an essential factor in adult glia functions and validates Drosophila as a beneficial 3Rs model to study glial functions and GBF1 biology. F1000Res 2020; 9:317. [PMID: 32595956 PMCID: PMC7309417 DOI: 10.12688/f1000research.23154.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/20/2020] [Indexed: 11/25/2022] Open
Abstract
Invertebrate glia performs most of the key functions controlled by mammalian glia in the nervous system and provides an ideal model for genetic studies of glial functions. To study the influence of adult glial cells in ageing we have performed a genetic screen in Drosophila using a collection of transgenic lines providing conditional expression of micro-RNAs (miRNAs). Here, we describe a methodological algorithm to identify and rank genes that are candidate to be targeted by miRNAs that shorten lifespan when expressed in adult glia. We have used four different databases for miRNA target prediction in Drosophila but find little agreement between them, overall. However, top candidate gene analysis shows potential to identify essential genes involved in adult glial functions. One example from our top candidates' analysis is gartenzwerg ( garz). We establish that garz is necessary in many glial cell types, that it affects motor behaviour and, at the sub-cellular level, is responsible for defects in cellular membranes, autophagy and mitochondria quality control. We also verify the remarkable conservation of functions between garz and its mammalian orthologue, GBF1, validating the use of Drosophila as an alternative 3Rs-beneficial model to knock-out mice for studying the biology of GBF1, potentially involved in human neurodegenerative diseases.
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Affiliation(s)
- Catarina Gonçalves-Pimentel
- Department of Basic and Clinical Neuroscience, King's College London, London, SE5 9NU, UK
- Champalimaud Research, Champalimaud Foundation, Av. Brasília, Lisbon, 1400-038, Portugal
| | - David Mazaud
- Department of Basic and Clinical Neuroscience, King's College London, London, SE5 9NU, UK
| | - Benjamin Kottler
- Department of Basic and Clinical Neuroscience, King's College London, London, SE5 9NU, UK
| | - Sandra Proelss
- Department of Basic and Clinical Neuroscience, King's College London, London, SE5 9NU, UK
| | - Frank Hirth
- Department of Basic and Clinical Neuroscience, King's College London, London, SE5 9NU, UK
| | - Manolis Fanto
- Department of Basic and Clinical Neuroscience, King's College London, London, SE5 9NU, UK
- Institut du Cerveau et de la Moelle épinière (ICM), 47, bd de l'hôpital, Paris, F-75013, France
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15
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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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16
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Uckeley ZM, Moeller R, Kühn LI, Nilsson E, Robens C, Lasswitz L, Lindqvist R, Lenman A, Passos V, Voss Y, Sommerauer C, Kampmann M, Goffinet C, Meissner F, Överby AK, Lozach PY, Gerold G. Quantitative Proteomics of Uukuniemi Virus-host Cell Interactions Reveals GBF1 as Proviral Host Factor for Phleboviruses. Mol Cell Proteomics 2019; 18:2401-2417. [PMID: 31570497 PMCID: PMC6885706 DOI: 10.1074/mcp.ra119.001631] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 09/15/2019] [Indexed: 12/20/2022] Open
Abstract
Novel tick-borne phleboviruses in the Phenuiviridae family, which are highly pathogenic in humans and all closely related to Uukuniemi virus (UUKV), have recently emerged on different continents. How phleboviruses assemble, bud, and exit cells remains largely elusive. Here, we performed high-resolution, label-free mass spectrometry analysis of UUKV immunoprecipitated from cell lysates and identified 39 cellular partners interacting with the viral envelope glycoproteins. The importance of these host factors for UUKV infection was validated by silencing each host factor by RNA interference. This revealed Golgi-specific brefeldin A-resistance guanine nucleotide exchange factor 1 (GBF1), a guanine nucleotide exchange factor resident in the Golgi, as a critical host factor required for the UUKV life cycle. An inhibitor of GBF1, Golgicide A, confirmed the role of the cellular factor in UUKV infection. We could pinpoint the GBF1 requirement to UUKV replication and particle assembly. When the investigation was extended to viruses from various positive and negative RNA viral families, we found that not only phleboviruses rely on GBF1 for infection, but also Flavi-, Corona-, Rhabdo-, and Togaviridae In contrast, silencing or blocking GBF1 did not abrogate infection by the human adenovirus serotype 5 and immunodeficiency retrovirus type 1, the replication of both requires nuclear steps. Together our results indicate that UUKV relies on GBF1 for viral replication, assembly and egress. This study also highlights the proviral activity of GBF1 in the infection by a broad range of important zoonotic RNA viruses.
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Affiliation(s)
- Zina M Uckeley
- CellNetworks Cluster of Excellence and Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany; CellNetworks Cluster of Excellence and Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Rebecca Moeller
- Institute for Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany; CellNetworks Cluster of Excellence and Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Lars I Kühn
- Experimental Systems Immunology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Emma Nilsson
- Division of Virology, Department of Clinical Microbiology, and Laboratory for Molecular Infection Medicine Sweden, Umeå University, Umeå, Sweden
| | - Claudia Robens
- CellNetworks Cluster of Excellence and Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Lisa Lasswitz
- Institute for Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany
| | - Richard Lindqvist
- Division of Virology, Department of Clinical Microbiology, and Laboratory for Molecular Infection Medicine Sweden, Umeå University, Umeå, Sweden
| | - Annasara Lenman
- Institute for Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany
| | - Vania Passos
- Institute for Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany; Instituto De Ciências Biomédicas Abel Salazar, Universidade Do Porto, Porto, Portugal
| | - Yannik Voss
- CellNetworks Cluster of Excellence and Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Christian Sommerauer
- CellNetworks Cluster of Excellence and Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Martin Kampmann
- CellNetworks Cluster of Excellence and Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Christine Goffinet
- Institute for Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany; Institute of Virology, Charité, Universitätsmedizin Berlin, Berlin, Germany and Berlin Institute of Health (BIH), Berlin, Germany
| | - Felix Meissner
- Experimental Systems Immunology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Anna K Överby
- Division of Virology, Department of Clinical Microbiology, and Laboratory for Molecular Infection Medicine Sweden, Umeå University, Umeå, Sweden
| | - Pierre-Yves Lozach
- CellNetworks Cluster of Excellence and Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany; IVPC UMR754, INRA, Univ. Lyon, EPHE, 50 Av. Tony Garnier, 69007 Lyon, France.
| | - Gisa Gerold
- Institute for Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany; Department of Clinical Microbiology, Virology & Wallenberg Centre for Molecular Medicine (WCMM), Umeå University, SE-90185 Umeå, Sweden.
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17
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Magliozzi R, Carrero ZI, Low TY, Yuniati L, Valdes-Quezada C, Kruiswijk F, van Wijk K, Heck AJR, Jackson CL, Guardavaccaro D. Inheritance of the Golgi Apparatus and Cytokinesis Are Controlled by Degradation of GBF1. Cell Rep 2019; 23:3381-3391.e4. [PMID: 29898406 DOI: 10.1016/j.celrep.2018.05.031] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 04/05/2018] [Accepted: 05/10/2018] [Indexed: 11/27/2022] Open
Abstract
Although much is known about how chromosome segregation is coupled to cell division, how intracellular organelles partition during mitotic division is poorly understood. We report that the phosphorylation-dependent degradation of the ARFGEF GBF1 regulates organelle trafficking during cell division. We show that, in mitosis, GBF1 is phosphorylated on Ser292 and Ser297 by casein kinase-2 allowing recognition by the F-box protein βTrCP. GBF1 interaction with βTrCP recruits GBF1 to the SCFβTrCP ubiquitin ligase complex, triggering its degradation. Phosphorylation and degradation of GBF1 occur along microtubules at the intercellular bridge of telophase cells and are required for Golgi membrane positioning and postmitotic Golgi reformation. Indeed, expression of a non-degradable GBF1 mutant inhibits the transport of the Golgi cluster adjacent to the midbody toward the Golgi twin positioned next to the centrosome and results in defective Golgi reassembly and cytokinesis failure. These findings define a mechanism that controls postmitotic Golgi reassembly and inheritance.
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Affiliation(s)
- Roberto Magliozzi
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 Utrecht, the Netherlands
| | - Zunamys I Carrero
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 Utrecht, the Netherlands
| | - Teck Yew Low
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 Utrecht, the Netherlands; The Netherlands Proteomics Center, Padualaan 8, 3584 Utrecht, the Netherlands
| | - Laurensia Yuniati
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 Utrecht, the Netherlands
| | - Christian Valdes-Quezada
- Oncode Institute, Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 Utrecht, the Netherlands
| | - Flore Kruiswijk
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 Utrecht, the Netherlands
| | - Koen van Wijk
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 Utrecht, the Netherlands
| | - Albert J R Heck
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 Utrecht, the Netherlands; The Netherlands Proteomics Center, Padualaan 8, 3584 Utrecht, the Netherlands
| | - Catherine L Jackson
- Membrane Dynamics and Intracellular Trafficking, Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, 75013 Paris, France
| | - Daniele Guardavaccaro
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 Utrecht, the Netherlands.
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18
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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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Awadia S, Huq F, Arnold TR, Goicoechea SM, Sun YJ, Hou T, Kreider-Letterman G, Massimi P, Banks L, Fuentes EJ, Miller AL, Garcia-Mata R. SGEF forms a complex with Scribble and Dlg1 and regulates epithelial junctions and contractility. J Cell Biol 2019; 218:2699-2725. [PMID: 31248911 PMCID: PMC6683736 DOI: 10.1083/jcb.201811114] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 03/18/2019] [Accepted: 04/12/2019] [Indexed: 01/15/2023] Open
Abstract
The canonical Scribble polarity complex is implicated in regulation of epithelial junctions and apical polarity. Here, we show that SGEF, a RhoG-specific GEF, forms a ternary complex with Scribble and Dlg1, two members of the Scribble complex. SGEF targets to apical junctions in a Scribble-dependent fashion and functions in the regulation of actomyosin-based contractility and barrier function at tight junctions as well as E-cadherin-mediated formation of adherens junctions. Surprisingly, SGEF does not control the establishment of polarity. However, in 3D cysts, SGEF regulates the formation of a single open lumen. Interestingly, SGEF's nucleotide exchange activity regulates the formation and maintenance of adherens junctions, and in cysts the number of lumens formed, whereas SGEF's scaffolding activity is critical for regulation of actomyosin contractility and lumen opening. We propose that SGEF plays a key role in coordinating junctional assembly and actomyosin contractility by bringing together Scribble and Dlg1 and targeting RhoG activation to cell-cell junctions.
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Affiliation(s)
- Sahezeel Awadia
- Department of Biological Sciences, The University of Toledo, Toledo, OH
| | - Farah Huq
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI
| | - Torey R Arnold
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI
| | | | - Young Joo Sun
- Department of Biochemistry, University of Iowa, Iowa City, IA
| | - Titus Hou
- Department of Biochemistry, University of Iowa, Iowa City, IA
| | | | - Paola Massimi
- International Center for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Lawrence Banks
- International Center for Genetic Engineering and Biotechnology, Trieste, Italy
| | | | - Ann L Miller
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI
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Regulatory role of Golgi brefeldin A resistance factor‐1 in amyloid precursor protein trafficking, cleavage and Aβ formation. J Cell Biochem 2019; 120:15604-15615. [DOI: 10.1002/jcb.28827] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 01/11/2019] [Accepted: 01/14/2019] [Indexed: 01/19/2023]
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21
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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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22
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The small GTPase RhoG regulates microtubule-mediated focal adhesion disassembly. Sci Rep 2019; 9:5163. [PMID: 30914742 PMCID: PMC6435757 DOI: 10.1038/s41598-019-41558-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 03/11/2019] [Indexed: 01/09/2023] Open
Abstract
Focal adhesions (FA) are a complex network of proteins that allow the cell to form physical contacts with the extracellular matrix (ECM). FA assemble and disassemble in a dynamic process, orchestrated by a variety of cellular components. However, the underlying mechanisms that regulate adhesion turnover remain poorly understood. Here we show that RhoG, a Rho GTPase related to Rac, modulates FA dynamics. When RhoG expression is silenced, FA are more stable and live longer, resulting in an increase in the number and size of adhesions, which are also more mature and fibrillar-like. Silencing RhoG also increases the number and thickness of stress fibers, which are sensitive to blebbistatin, suggesting contractility is increased. The molecular mechanism by which RhoG regulates adhesion turnover is yet to be characterized, but our results demonstrate that RhoG plays a role in the regulation of microtubule-mediated FA disassembly.
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23
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Pocognoni CA, Viktorova EG, Wright J, Meissner JM, Sager G, Lee E, Belov GA, Sztul E. Highly conserved motifs within the large Sec7 ARF guanine nucleotide exchange factor GBF1 target it to the Golgi and are critical for GBF1 activity. Am J Physiol Cell Physiol 2018; 314:C675-C689. [PMID: 29443553 DOI: 10.1152/ajpcell.00221.2017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cellular life requires the activation of the ADP-ribosylation factors (ARFs) by Golgi brefeldin A-resistant factor 1 (GBF1), a guanine nucleotide exchange factor (GEF) with a highly conserved catalytic Sec7 domain (Sec7d). In addition to the Sec7d, GBF1 contains other conserved domains whose functions remain unclear. Here, we focus on HDS2 (homology downstream of Sec7d 2) domain because the L1246R substitution within the HDS2 α-helix 5 of the zebrafish GBF1 ortholog causes vascular hemorrhaging and embryonic lethality (13). To dissect the structure/function relationships within HDS2, we generated six variants, in which the most conserved residues within α-helices 1, 2, 4, and 6 were mutated to alanines. Each HDS2 mutant was assessed in a cell-based "replacement" assay for its ability to support cellular functions normally supported by GBF1, such as maintaining Golgi homeostasis, facilitating COPI recruitment, supporting secretion, and sustaining cellular viability. We show that cells treated with the pharmacological GBF1 inhibitor brefeldin A (BFA) and expressing a BFA-resistant GBF1 variant with alanine substitutions of RDR1168 or LF1266 are compromised in Golgi homeostasis, impaired in ARF activation, unable to sustain secretion, and defective in maintaining cellular viability. To gain insight into the molecular mechanism of this dysfunction, we assessed the ability of each GBF1 mutant to target to Golgi membranes and found that mutations in RDR1168 and LF1266 significantly decrease targeting efficiency. Thus, these residues within α-helix 2 and α-helix 6 of the HDS2 domain in GBF1 are novel regulatory determinants that support GBF1 cellular function by impacting the Golgi-specific membrane association of GBF1.
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Affiliation(s)
- Cristian A Pocognoni
- 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
| | - John Wright
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham , Birmingham, Alabama
| | - Justyna M Meissner
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham , Birmingham, Alabama
| | - Garrett Sager
- 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
| | - George A Belov
- Department of Veterinary Medicine, Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland , College Park, Maryland
| | - Elizabeth Sztul
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham , Birmingham, Alabama
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24
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Meissner JM, Bhatt JM, Lee E, Styers ML, Ivanova AA, Kahn RA, Sztul E. The ARF guanine nucleotide exchange factor GBF1 is targeted to Golgi membranes through a PIP-binding domain. J Cell Sci 2018; 131:jcs.210245. [PMID: 29361542 DOI: 10.1242/jcs.210245] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 12/15/2017] [Indexed: 11/20/2022] Open
Abstract
ADP-ribosylation factors (ARF) GTPases are activated by guanine nucleotide exchange factors (GEFs) to support cellular homeostasis. Key to understanding spatio-temporal regulation of ARF signaling is the mechanism of GEF recruitment to membranes. Small GEFs are recruited through phosphoinositide (PIP) binding by a pleckstrin homology (PH) domain downstream from the catalytic Sec7 domain (Sec7d). The large GEFs lack PH domains, and their recruitment mechanisms are poorly understood. We probed Golgi recruitment of GBF1, a GEF catalyzing ARF activation required for Golgi homeostasis. We show that the homology downstream of Sec7d-1 (HDS1) regulates Golgi recruitment of GBF1. We document that GBF1 binds phosphoinositides, preferentially PI3P, PI4P and PI(4,5)P2, and that lipid binding requires the HDS1 domain. Mutations within HDS1 that reduce GBF1 binding to specific PIPs in vitro inhibit GBF1 targeting to Golgi membranes in cells. Our data imply that HDS1 and PH domains are functionally analogous in that each uses lipid-based membrane information to regulate GEF recruitment. Lipid-based recruitment of GBF1 extends the paradigm of lipid regulation to small and large GEFs and suggests that lipid-based mechanisms evolved early during GEF diversification. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Justyna M Meissner
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Jay M Bhatt
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Eunjoo Lee
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Melanie L Styers
- Department of Biology, Birmingham-Southern College, Birmingham, AL 35254, USA
| | - Anna A Ivanova
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Richard A Kahn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Elizabeth Sztul
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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25
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Abstract
In eukaryotes, distinct transport vesicles functionally connect various intracellular compartments. These carriers mediate transport of membranes for the biogenesis and maintenance of organelles, secretion of cargo proteins and peptides, and uptake of cargo into the cell. Transport vesicles have distinct protein coats that assemble on a donor membrane where they can select cargo and curve the membrane to form a bud. A multitude of structural elements of coat proteins have been solved by X-ray crystallography. More recently, the architectures of the COPI and COPII coats were elucidated in context with their membrane by cryo-electron tomography. Here, we describe insights gained from the structures of these two coat lattices and discuss the resulting functional implications.
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Affiliation(s)
- Julien Béthune
- Heidelberg University Biochemistry Centre, 69120 Heidelberg, Germany; ,
| | - Felix T Wieland
- Heidelberg University Biochemistry Centre, 69120 Heidelberg, Germany; ,
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26
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García IA, Torres Demichelis V, Viale DL, Di Giusto P, Ezhova Y, Polishchuk RS, Sampieri L, Martinez H, Sztul E, Alvarez C. CREB3L1-mediated functional and structural adaptation of the secretory pathway in hormone-stimulated thyroid cells. J Cell Sci 2017; 130:4155-4167. [PMID: 29093023 DOI: 10.1242/jcs.211102] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 10/11/2017] [Indexed: 01/22/2023] Open
Abstract
Many secretory cells increase the synthesis and secretion of cargo proteins in response to specific stimuli. How cells couple increased cargo load with a coordinate rise in secretory capacity to ensure efficient transport is not well understood. We used thyroid cells stimulated with thyrotropin (TSH) to demonstrate a coordinate increase in the production of thyroid-specific cargo proteins and ER-Golgi transport factors, and a parallel expansion of the Golgi complex. TSH also increased expression of the CREB3L1 transcription factor, which alone caused amplified transport factor levels and Golgi enlargement. Furthermore, CREB3L1 potentiated the TSH-induced increase in Golgi volume. A dominant-negative CREB3L1 construct hampered the ability of TSH to induce Golgi expansion, implying that this transcription factor contributes to Golgi expansion. Our findings support a model in which CREB3L1 acts as a downstream effector of TSH to regulate the expression of cargo proteins, and simultaneously increases the synthesis of transport factors and the expansion of the Golgi to synchronize the rise in cargo load with the amplified capacity of the secretory pathway.
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Affiliation(s)
- Iris A García
- Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI-CONICET), Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba 5000, Argentina
| | - Vanina Torres Demichelis
- Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI-CONICET), Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba 5000, Argentina
| | - Diego L Viale
- Laboratorio de Neuro y Citogenetica Molecular, Centro de Estudios en Salud y Medio Ambiente, Escuela de Ciencia y Tecnologi-Universidad Nacional de San Martiń-CONICET, Buenos Aires, B1650 WAB, Argentina
| | - Pablo Di Giusto
- Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI-CONICET), Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba 5000, Argentina
| | - Yulia Ezhova
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei, 34, 80078, Pozzuoli (NA), Italy
| | - Roman S Polishchuk
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei, 34, 80078, Pozzuoli (NA), Italy
| | - Luciana Sampieri
- Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI-CONICET), Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba 5000, Argentina
| | - Hernán Martinez
- Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI-CONICET), Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba 5000, Argentina
| | - Elizabeth Sztul
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35233-2008, USA
| | - Cecilia Alvarez
- Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI-CONICET), Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba 5000, Argentina
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27
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Wang J, Fresquez T, Kandachar V, Deretic D. The Arf GEF GBF1 and Arf4 synergize with the sensory receptor cargo, rhodopsin, to regulate ciliary membrane trafficking. J Cell Sci 2017; 130:3975-3987. [PMID: 29025970 DOI: 10.1242/jcs.205492] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 10/10/2017] [Indexed: 01/05/2023] Open
Abstract
The small GTPase Arf4 and the Arf GTPase-activating protein (GAP) ASAP1 cooperatively sequester sensory receptor cargo into transport carriers targeted to primary cilia, but the input that drives Arf4 activation in this process remains unknown. Here, we show, by using frog retinas and recombinant human proteins, that during the carrier biogenesis from the photoreceptor Golgi/trans-Golgi network (TGN) a functional complex is formed between Arf4, the Arf guanine nucleotide exchange factor (GEF) GBF1 and the light-sensing receptor, rhodopsin. Rhodopsin and Arf4 bind the regulatory N-terminal dimerization and cyclophillin-binding (DCB)-homology upstream of Sec7 (HUS) domain of GBF1. The complex is sensitive to Golgicide A (GCA), a selective inhibitor of GBF1 that accordingly blocks rhodopsin delivery to the cilia, without disrupting the photoreceptor Golgi. The emergence of newly synthesized rhodopsin in the endomembrane system is essential for GBF1-Arf4 complex formation in vivo Notably, GBF1 interacts with the Arf GAP ASAP1 in a GCA-resistant manner. Our findings indicate that converging signals on GBF1 from the influx of cargo into the Golgi/TGN and the feedback from Arf4, combined with input from ASAP1, control Arf4 activation during sensory membrane trafficking to primary cilia.
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Affiliation(s)
- Jing Wang
- Department of Surgery, Division of Ophthalmology, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Theresa Fresquez
- Department of Surgery, Division of Ophthalmology, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Vasundhara Kandachar
- Department of Surgery, Division of Ophthalmology, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Dusanka Deretic
- Department of Surgery, Division of Ophthalmology, University of New Mexico, Albuquerque, New Mexico 87131, USA .,Cell Biology and Physiology, University of New Mexico, Albuquerque, New Mexico 87131, USA
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28
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Valdivia A, Goicoechea SM, Awadia S, Zinn A, Garcia-Mata R. Regulation of circular dorsal ruffles, macropinocytosis, and cell migration by RhoG and its exchange factor, Trio. Mol Biol Cell 2017; 28:1768-1781. [PMID: 28468978 PMCID: PMC5491185 DOI: 10.1091/mbc.e16-06-0412] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 04/20/2017] [Accepted: 04/25/2017] [Indexed: 11/11/2022] Open
Abstract
The small GTPase RhoG and its exchange factor, Trio, regulate the formation and size of circular dorsal ruffles and associated functions, including macropinocytosis and cell migration. Circular dorsal ruffles (CDRs) are actin-rich structures that form on the dorsal surface of many mammalian cells in response to growth factor stimulation. CDRs represent a unique type of structure that forms transiently and only once upon stimulation. The formation of CDRs involves a drastic rearrangement of the cytoskeleton, which is regulated by the Rho family of GTPases. So far, only Rac1 has been consistently associated with CDR formation, whereas the role of other GTPases in this process is either lacking or inconclusive. Here we show that RhoG and its exchange factor, Trio, play a role in the regulation of CDR dynamics, particularly by modulating their size. RhoG is activated by Trio downstream of PDGF in a PI3K- and Src-dependent manner. Silencing RhoG expression decreases the number of cells that form CDRs, as well as the area of the CDRs. The regulation of CDR area by RhoG is independent of Rac1 function. In addition, our results show the RhoG plays a role in the cellular functions associated with CDR formation, including macropinocytosis, receptor internalization, and cell migration. Taken together, our results reveal a novel role for RhoG in the regulation of CDRs and the cellular processes associated with their formation.
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Affiliation(s)
- Alejandra Valdivia
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606.,Division of Cardiology, School of Medicine, Emory University, Atlanta, GA 30322
| | | | - Sahezeel Awadia
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606
| | - Ashtyn Zinn
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606
| | - Rafael Garcia-Mata
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606
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29
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Busby T, Meissner JM, Styers ML, Bhatt J, Kaushik A, Hjelmeland AB, Sztul E. The Arf activator GBF1 localizes to plasma membrane sites involved in cell adhesion and motility. CELLULAR LOGISTICS 2017; 7:e1308900. [PMID: 28702273 DOI: 10.1080/21592799.2017.1308900] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 02/20/2017] [Accepted: 03/14/2017] [Indexed: 10/24/2022]
Affiliation(s)
- Theodore Busby
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Justyna M Meissner
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Melanie L Styers
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Jay Bhatt
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Akhil Kaushik
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Anita B Hjelmeland
- Department of Cell, Developmental and Integrative Biology, 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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30
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Wang Y, Zhang H, Shi M, Liou YC, Lu L, Yu F. Sec71 functions as a GEF for the small GTPase Arf1 to govern dendrite pruning of Drosophila sensory neurons. Development 2017; 144:1851-1862. [DOI: 10.1242/dev.146175] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 03/29/2017] [Indexed: 01/20/2023]
Abstract
Pruning, whereby neurons eliminate their exuberant neurites, is central for the maturation of the nervous system. In Drosophila, sensory neurons, ddaCs, selectively prune their larval dendrites without affecting their axons during metamorphosis. However, it is unknown whether the secretory pathway plays a role in dendrite pruning. Here, we show that the small GTPase Arf1, an important regulator of secretory pathway, is specifically required for dendrite pruning of ddaC/D/E sensory neurons but dispensable for apoptosis of ddaF neurons. Analyses of the GTP and GDP-locked forms of Arf1 indicate that the cycling of Arf1 between GDP-bound and GTP-bound forms is essential for dendrite pruning. We further identified Sec71 as a guanine nucleotide exchange factor for Arf1 that preferentially interacts with its GDP-bound form. Like Arf1, Sec71 is also important for dendrite pruning, but not apoptosis, of sensory neurons. Arf1 and Sec71 are interdependent for their localizations on Golgi. Finally, we show that Sec71/Arf1-mediated trafficking process is a prerequisite for Rab5-dependent endocytosis to facilitate endocytosis and degradation of the cell adhesion molecule Neuroglian (Nrg).
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Affiliation(s)
- Yan Wang
- Temasek Life Sciences Laboratory and Department of Biological Sciences, 1 Research Link, National University of Singapore, Singapore, 117604
- NUS Graduate School for Integrative Sciences and Engineering, Centre for Life Sciences, Singapore, 117456
| | - Heng Zhang
- Temasek Life Sciences Laboratory and Department of Biological Sciences, 1 Research Link, National University of Singapore, Singapore, 117604
| | - Meng Shi
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551
| | - Yih-Cherng Liou
- Temasek Life Sciences Laboratory and Department of Biological Sciences, 1 Research Link, National University of Singapore, Singapore, 117604
- NUS Graduate School for Integrative Sciences and Engineering, Centre for Life Sciences, Singapore, 117456
| | - Lei Lu
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551
| | - Fengwei Yu
- Temasek Life Sciences Laboratory and Department of Biological Sciences, 1 Research Link, National University of Singapore, Singapore, 117604
- NUS Graduate School for Integrative Sciences and Engineering, Centre for Life Sciences, Singapore, 117456
- Neuroscience and Behavioral Disorder Program, Duke-NUS Graduate Medical School Singapore, 8 College Road, Singapore, 169857
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31
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Chen J, Wu X, Yao L, Yan L, Zhang L, Qiu J, Liu X, Jia S, Meng A. Impairment of Cargo Transportation Caused by gbf1 Mutation Disrupts Vascular Integrity and Causes Hemorrhage in Zebrafish Embryos. J Biol Chem 2016; 292:2315-2327. [PMID: 28003365 DOI: 10.1074/jbc.m116.767608] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 12/19/2016] [Indexed: 12/11/2022] Open
Abstract
ADP-ribosylation factor GTPases are activated by guanine nucleotide exchange factors including Gbf1 (Golgi brefeldin A-resistant factor 1) and play important roles in regulating organelle structure and cargo-selective vesicle trafficking. However, the developmental role of Gbf1 in vertebrates remains elusive. In this study, we report the zebrafish mutant line tsu3994 that arises from N-ethyl-N-nitrosourea (ENU)-mediated mutagenesis and is characterized by prominent intracerebral and trunk hemorrhage. The mutant embryos develop hemorrhage accompanied by fewer pigments and shorter caudal fin at day 2 of development. The hemorrhage phenotype is caused by vascular breakage in a cell autonomous fashion. Positional cloning identifies a T → G nucleotide substitution in the 23rd exon of the gbf1 locus, resulting in a leucine → arginine substitution (L1246R) in the HDS2 domain. The mutant phenotype is mimicked by gbf1 knockouts and morphants, suggesting a nature of loss of function. Experimental results in mammalian cells show that the mutant form Gbf1(L1246R) is unable to be recruited to the Golgi apparatus and fails to activate Arf1 for recruiting COPI complex. The hemorrhage in tsu3994 mutants can be prevented partially and temporally by treating with the endoplasmic reticulum stress/apoptosis inhibitor tauroursodeoxycholic acid or by knocking down the proapoptotic gene baxb Therefore, endothelial endoplasmic reticulum stress and subsequent apoptosis induced by gbf1 deficiency may account for the vascular collapse and hemorrhage.
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Affiliation(s)
- Jing Chen
- From the Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xiaotong Wu
- From the Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Likun Yao
- From the Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Lu Yan
- From the Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Lin Zhang
- From the Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Juhui Qiu
- From the Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xingfeng Liu
- From the Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Shunji Jia
- From the Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Anming Meng
- From the Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
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32
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Expression of Epitope-Tagged Proteins in Mammalian Cells in Culture. Methods Mol Biol 2016. [PMID: 27515071 DOI: 10.1007/978-1-4939-6352-2_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Before the advent of molecular methods to tag proteins, visualization of proteins within cells required the use of antibodies directed against the protein of interest. Thus, only proteins for which antibodies were available could be visualized. Epitope tagging allows the detection of all proteins with existing sequence information, irrespective of the availability of antibodies directed against them. This technique involves the generation of DNA constructs that express the protein of interest tagged with an epitope that can be recognized by a commercially available antibody. Proteins can be tagged with a wide variety of epitopes using commercially available vectors that allow expression in mammalian cells. Epitope-tagged proteins are easily transfected into mammalian cell lines and, in most cases, tightly mimic the behavior of the endogenous protein. Tagged proteins exogenously expressed in cells provide different types of information depending on the subsequent detection approaches. Using immunofluorescence and immunoelectron microscopy with anti-tag antibodies, relative to known markers of cellular organelles, can provide information on the subcellular localization of the tagged protein and may provide clues regarding the protein's function. Immunofluorescence with anti-tag antibodies can also be utilized to assess the tagged protein's responses to cellular signals and pharmacological treatments. Immunoprecipitations with anti-tag antibodies can recover protein complexes containing the protein of interest, resulting in the identification of interacting proteins. Recovery of tagged proteins on affinity matrices allows their purification for use in biochemical assays. In addition, specialized fluorescent tags, such as the green fluorescent protein (GFP) allow the analysis of cellular dynamics in live cells in real time.
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Martinez H, García IA, Sampieri L, Alvarez C. Spatial-Temporal Study of Rab1b Dynamics and Function at the ER-Golgi Interface. PLoS One 2016; 11:e0160838. [PMID: 27500526 PMCID: PMC4976911 DOI: 10.1371/journal.pone.0160838] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2015] [Accepted: 07/26/2016] [Indexed: 12/27/2022] Open
Abstract
The GTPase Rab1b is involved in ER to Golgi transport, with multiple Rab1b effectors (located at ERES, VTCs and the Golgi complex) being required for its function. In this study, we performed live-cell dual-expression studies to analyze the dynamics of Rab1b and some effectors located at the ERES-Golgi interface. Rab1b occupied widely distributed mobile punctate and tubular structures, displaying a transient overlaps with its effectors and showing that these overlaps occurred at the same time in spatially distinct steps of ER to Golgi transport. In addition, we assessed Rab1b dynamics during cargo sorting by analyzing the concentration at ERES of a Golgi protein (SialT2-CFP) during Brefeldin A washout (BFA WO). Rab1b was associated to most of the ERES structures, but at different times during BFA WO, and recurrently SialT2-CFP was sorted in the ERES-Rab1b positive structures. Furthermore, we reveal for first time that Rab1b localization time at ERES depended on GBF1, a Rab1b effector that acts as the guanine nucleotide exchange factor of Arf1, and that Rab1b membrane association/dissociation dynamics at ERES was dependent on the GBF1 membrane association and activity, which strongly suggests that GBF1 activity modulates Rab1b membrane cycling dynamic.
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Affiliation(s)
- Hernán Martinez
- Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI-CONICET), Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba 5000, Argentina
| | - Iris A. García
- Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI-CONICET), Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba 5000, Argentina
| | - Luciana Sampieri
- Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI-CONICET), Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba 5000, Argentina
| | - Cecilia Alvarez
- Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI-CONICET), Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba 5000, Argentina
- * E-mail:
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Saraste J, Marie M. Intermediate Compartment: A Sorting Station between the Endoplasmic Reticulum and the Golgi Apparatus. ENCYCLOPEDIA OF CELL BIOLOGY 2016. [PMCID: PMC7150006 DOI: 10.1016/b978-0-12-394447-4.20013-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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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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Covington JD, Noland RC, Hebert RC, Masinter BS, Smith SR, Rustan AC, Ravussin E, Bajpeyi S. Perilipin 3 Differentially Regulates Skeletal Muscle Lipid Oxidation in Active, Sedentary, and Type 2 Diabetic Males. J Clin Endocrinol Metab 2015; 100:3683-92. [PMID: 26171795 PMCID: PMC4596049 DOI: 10.1210/jc.2014-4125] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
CONTEXT The role of perilipin 3 (PLIN3) on lipid oxidation is not fully understood. OBJECTIVE We aimed to 1) determine whether skeletal muscle PLIN3 protein content is associated with lipid oxidation in humans, 2) understand the role of PLIN3 in lipid oxidation by knocking down PLIN3 protein content in primary human myotubes, and 3) compare PLIN3 content and its role in lipid oxidation in human primary skeletal muscle cultures established from sedentary, healthy lean (leans), type 2 diabetic (T2D), and physically active donors. DESIGN, PARTICIPANTS, AND INTERVENTION This was a clinical investigation of 29 healthy, normoglycemic males and a cross-sectional study using primary human myotubes from five leans, four T2D, and four active donors. Energy expenditure, whole-body lipid oxidation, PLIN3 protein content in skeletal muscle tissue, and ex vivo muscle palmitate oxidation were measured. Myotubes underwent lipolytic stimulation (palmitate, forskolin, inomycin [PFI] cocktail), treatment with brefeldin A (BFA), and knockdown of PLIN3 using siRNA. SETTING Experiments were performed in a Biomedical Research Institute. MAIN OUTCOME MEASURES Protein content, 24-hour respiratory quotient (RQ), and ex vivo/in vitro lipid oxidations. RESULTS PLIN3 protein content was associated with 24-h RQ (r = -0.44; P = .02) and skeletal muscle-specific ex vivo palmitate oxidation (r = 0.61; P = .02). PLIN3 knockdown showed drastic reductions in lipid oxidation in myotubes from leans. Lipolytic stimulation increased PLIN3 protein in cells from leans over T2Ds with little expression in active participants. Furthermore, treatment with BFA, known to inhibit coatomers that associate with PLIN3, reduced lipid oxidation in cells from lean and T2D, but not in active participants. CONCLUSIONS Differential expression of PLIN3 and BFA sensitivity may explain differential lipid oxidation efficiency in skeletal muscle among these cohorts.
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Affiliation(s)
- Jeffrey D Covington
- Pennington Biomedical Research Center (J.D.C., R.C.N., R.C.H., B.S.M., E.R., S.B.), Laboratory of Skeletal Muscle Physiology, Baton Rouge, Louisiana 70808; Louisiana State University Health Sciences Center (J.D.C.), School of Medicine, New Orleans, Louisiana 70112; Translational Research Institute for Metabolism and Diabetes (S.R.S.), Florida Hospital, Sanford-Burnham Medical Research Institute, Winter Park, Florida 32789; Department of Pharmaceutical Biosciences (A.C.R.), University of Oslo, Oslo, Norway; and Department of Kinesiology (S.B.), University of Texas-El Paso, El Paso, Texas 79968
| | - Robert C Noland
- Pennington Biomedical Research Center (J.D.C., R.C.N., R.C.H., B.S.M., E.R., S.B.), Laboratory of Skeletal Muscle Physiology, Baton Rouge, Louisiana 70808; Louisiana State University Health Sciences Center (J.D.C.), School of Medicine, New Orleans, Louisiana 70112; Translational Research Institute for Metabolism and Diabetes (S.R.S.), Florida Hospital, Sanford-Burnham Medical Research Institute, Winter Park, Florida 32789; Department of Pharmaceutical Biosciences (A.C.R.), University of Oslo, Oslo, Norway; and Department of Kinesiology (S.B.), University of Texas-El Paso, El Paso, Texas 79968
| | - R Caitlin Hebert
- Pennington Biomedical Research Center (J.D.C., R.C.N., R.C.H., B.S.M., E.R., S.B.), Laboratory of Skeletal Muscle Physiology, Baton Rouge, Louisiana 70808; Louisiana State University Health Sciences Center (J.D.C.), School of Medicine, New Orleans, Louisiana 70112; Translational Research Institute for Metabolism and Diabetes (S.R.S.), Florida Hospital, Sanford-Burnham Medical Research Institute, Winter Park, Florida 32789; Department of Pharmaceutical Biosciences (A.C.R.), University of Oslo, Oslo, Norway; and Department of Kinesiology (S.B.), University of Texas-El Paso, El Paso, Texas 79968
| | - Blaine S Masinter
- Pennington Biomedical Research Center (J.D.C., R.C.N., R.C.H., B.S.M., E.R., S.B.), Laboratory of Skeletal Muscle Physiology, Baton Rouge, Louisiana 70808; Louisiana State University Health Sciences Center (J.D.C.), School of Medicine, New Orleans, Louisiana 70112; Translational Research Institute for Metabolism and Diabetes (S.R.S.), Florida Hospital, Sanford-Burnham Medical Research Institute, Winter Park, Florida 32789; Department of Pharmaceutical Biosciences (A.C.R.), University of Oslo, Oslo, Norway; and Department of Kinesiology (S.B.), University of Texas-El Paso, El Paso, Texas 79968
| | - Steven R Smith
- Pennington Biomedical Research Center (J.D.C., R.C.N., R.C.H., B.S.M., E.R., S.B.), Laboratory of Skeletal Muscle Physiology, Baton Rouge, Louisiana 70808; Louisiana State University Health Sciences Center (J.D.C.), School of Medicine, New Orleans, Louisiana 70112; Translational Research Institute for Metabolism and Diabetes (S.R.S.), Florida Hospital, Sanford-Burnham Medical Research Institute, Winter Park, Florida 32789; Department of Pharmaceutical Biosciences (A.C.R.), University of Oslo, Oslo, Norway; and Department of Kinesiology (S.B.), University of Texas-El Paso, El Paso, Texas 79968
| | - Arild C Rustan
- Pennington Biomedical Research Center (J.D.C., R.C.N., R.C.H., B.S.M., E.R., S.B.), Laboratory of Skeletal Muscle Physiology, Baton Rouge, Louisiana 70808; Louisiana State University Health Sciences Center (J.D.C.), School of Medicine, New Orleans, Louisiana 70112; Translational Research Institute for Metabolism and Diabetes (S.R.S.), Florida Hospital, Sanford-Burnham Medical Research Institute, Winter Park, Florida 32789; Department of Pharmaceutical Biosciences (A.C.R.), University of Oslo, Oslo, Norway; and Department of Kinesiology (S.B.), University of Texas-El Paso, El Paso, Texas 79968
| | - Eric Ravussin
- Pennington Biomedical Research Center (J.D.C., R.C.N., R.C.H., B.S.M., E.R., S.B.), Laboratory of Skeletal Muscle Physiology, Baton Rouge, Louisiana 70808; Louisiana State University Health Sciences Center (J.D.C.), School of Medicine, New Orleans, Louisiana 70112; Translational Research Institute for Metabolism and Diabetes (S.R.S.), Florida Hospital, Sanford-Burnham Medical Research Institute, Winter Park, Florida 32789; Department of Pharmaceutical Biosciences (A.C.R.), University of Oslo, Oslo, Norway; and Department of Kinesiology (S.B.), University of Texas-El Paso, El Paso, Texas 79968
| | - Sudip Bajpeyi
- Pennington Biomedical Research Center (J.D.C., R.C.N., R.C.H., B.S.M., E.R., S.B.), Laboratory of Skeletal Muscle Physiology, Baton Rouge, Louisiana 70808; Louisiana State University Health Sciences Center (J.D.C.), School of Medicine, New Orleans, Louisiana 70112; Translational Research Institute for Metabolism and Diabetes (S.R.S.), Florida Hospital, Sanford-Burnham Medical Research Institute, Winter Park, Florida 32789; Department of Pharmaceutical Biosciences (A.C.R.), University of Oslo, Oslo, Norway; and Department of Kinesiology (S.B.), University of Texas-El Paso, El Paso, Texas 79968
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Microsomal Triglyceride Transfer Protein (MTP) Associates with Cytosolic Lipid Droplets in 3T3-L1 Adipocytes. PLoS One 2015; 10:e0135598. [PMID: 26267806 PMCID: PMC4534446 DOI: 10.1371/journal.pone.0135598] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 07/16/2015] [Indexed: 12/18/2022] Open
Abstract
Lipid droplets are intracellular energy storage organelles composed of a hydrophobic core of neutral lipid, surrounded by a monolayer of phospholipid and a diverse array of proteins. The function of the vast majority of these proteins with regard to the formation and/or turnover of lipid droplets is unknown. Our laboratory was the first to report that microsomal triglyceride transfer protein (MTP), a lipid transfer protein essential for the assembly of triglyceride-rich lipoproteins, was expressed in adipose tissue of humans and mice. In addition, our studies suggested that MTP was associated with lipid droplets in both brown and white fat. Our observations led us to hypothesize that MTP plays a key role in lipid droplet formation and/or turnover. The objective of these studies was to gain insight into the function of MTP in adipocytes. Using molecular, biochemical, and morphologic approaches we have shown: 1) MTP protein levels increase nearly five-fold as 3T3-L1 cells differentiate into adipocytes. 2) As 3T3-L1 cells undergo differentiation, MTP moves from the juxtanuclear region of the cell to the surface of lipid droplets. MTP and perilipin 2, a major lipid droplet surface protein, are found on the same droplets; however, MTP does not co-localize with perilipin 2. 3) Inhibition of MTP activity has no effect on the movement of triglyceride out of the cell either as a lipid complex or via lipolysis. 4) MTP is found associated with lipid droplets within hepatocytes from human fatty livers, suggesting that association of MTP with lipid droplets is not restricted to adipocytes. In summary, our data demonstrate that MTP is a lipid droplet-associated protein. Its location on the surface of the droplet in adipocytes and hepatocytes, coupled with its known function as a lipid transfer protein and its increased expression during adipocyte differentiation suggest a role in lipid droplet biology.
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Benyair R, Ogen-Shtern N, Mazkereth N, Shai B, Ehrlich M, Lederkremer GZ. Mammalian ER mannosidase I resides in quality control vesicles, where it encounters its glycoprotein substrates. Mol Biol Cell 2014; 26:172-84. [PMID: 25411339 PMCID: PMC4294666 DOI: 10.1091/mbc.e14-06-1152] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
ER mannosidase I (ERManI) was found recently in the Golgi. This result is found to arise artificially from membrane disturbance in immunofluorescence methods. ERManI is located in novel vesicles to which substrates traffic and that converge at the ER-derived quality control compartment under ER stress. Endoplasmic reticulum α1,2 mannosidase I (ERManI), a central component of ER quality control and ER-associated degradation (ERAD), acts as a timer enzyme, modifying N-linked sugar chains of glycoproteins with time. This process halts glycoprotein folding attempts when necessary and targets terminally misfolded glycoproteins to ERAD. Despite the importance of ERManI in maintenance of glycoprotein quality control, fundamental questions regarding this enzyme remain controversial. One such question is the subcellular localization of ERManI, which has been suggested to localize to the ER membrane, the ER-derived quality control compartment (ERQC), and, surprisingly, recently to the Golgi apparatus. To try to clarify this controversy, we applied a series of approaches that indicate that ERManI is located, at the steady state, in quality control vesicles (QCVs) to which ERAD substrates are transported and in which they interact with the enzyme. Both endogenous and exogenously expressed ERManI migrate at an ER-like density on iodixanol gradients, suggesting that the QCVs are derived from the ER. The QCVs are highly mobile, displaying dynamics that are dependent on microtubules and COP-II but not on COP-I vesicle machinery. Under ER stress conditions, the QCVs converge in a juxtanuclear region, at the ERQC, as previously reported. Our results also suggest that ERManI is turned over by an active autophagic process. Of importance, we found that membrane disturbance, as is common in immunofluorescence methods, leads to an artificial appearance of ERManI in a Golgi pattern.
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Affiliation(s)
- Ron Benyair
- Department of Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Navit Ogen-Shtern
- Department of Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Niv Mazkereth
- Department of Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ben Shai
- Department of Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Marcelo Ehrlich
- Department of Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Gerardo Z Lederkremer
- Department of Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
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Martínez-Martínez N, Martínez-Alonso E, Ballesta J, Martínez-Menárguez JA. Phospholipase D2 is involved in the formation of Golgi tubules and ArfGAP1 recruitment. PLoS One 2014; 9:e111685. [PMID: 25354038 PMCID: PMC4213061 DOI: 10.1371/journal.pone.0111685] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 10/03/2014] [Indexed: 11/19/2022] Open
Abstract
Lipids and lipid-modifying enzymes play a key role in the biogenesis, maintenance and fission of transport carriers in the secretory and endocytic pathways. In the present study we demonstrate that phosphatidic acid generated by phospholipase D2 (PLD2) is involved in the formation of Golgi tubules. The main evidence to support this is: 1) inhibitors of phosphatidic acid formation and PLD2 depletion inhibit the formation of tubules containing resident enzymes and regulators of intra-Golgi transport in a low temperature (15°C) model of Golgi tubulation but do not affect brefeldin A-induced tubules, 2) inhibition of PLD2 enzymatic activity and PLD2 depletion in cells cultured under physiological conditions (37°C) induce the formation of tubules specifically containing Golgi matrix proteins, and, 3) over-expression of PLD2 induces the formation of a tubular network. In addition, it was found that the generation of this lipid by the isoenzyme is necessary for ArfGAP1 recruitment to Golgi membranes. These results suggest that both proteins are involved in the molecular mechanisms which drive the formation of different types of Golgi tubules.
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Affiliation(s)
- Narcisa Martínez-Martínez
- Department of Cell Biology and Histology, Medical School, IMIB-Arrixaca, University of Murcia, Murcia, Spain
| | - Emma Martínez-Alonso
- Department of Cell Biology and Histology, Medical School, IMIB-Arrixaca, University of Murcia, Murcia, Spain
| | - José Ballesta
- Department of Cell Biology and Histology, Medical School, IMIB-Arrixaca, University of Murcia, Murcia, Spain
| | - José A. Martínez-Menárguez
- Department of Cell Biology and Histology, Medical School, IMIB-Arrixaca, University of Murcia, Murcia, Spain
- * E-mail:
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Szul T, Burgess J, Jeon M, Zinn K, Marques G, Brill JA, Sztul E. The Garz Sec7 domain guanine nucleotide exchange factor for Arf regulates salivary gland development in Drosophila. CELLULAR LOGISTICS 2014; 1:69-76. [PMID: 21686256 DOI: 10.4161/cl.1.2.15512] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Revised: 03/11/2011] [Accepted: 03/17/2011] [Indexed: 12/22/2022]
Abstract
Surface delivery of proteins involved in cell-cell and cell-matrix interactions in cultured mammalian cells requires the GBF1 guanine nucleotide exchange factor. However, the role of GBF1 in delivery of adhesion proteins during organogenesis in intact animals has not been characterized. Here, we report the function of the fly GBF1 homolog, Gartenzwerg (Garz) in the development of the salivary gland in Drosophila melanogaster. We used the GAL4/UAS system to selectively deplete Garz from salivary gland cells. We show that depletion of Garz disrupts the secretory pathway as evidenced by the collapse of Golgi-localized Lava lamp (Lva) and the TGN-localized γ subunit of the clathrin-adaptor protein complex (AP-1). Additionally, Garz depletion inhibits trafficking of cell-cell adhesion proteins cadherin (DE-cad) and Flamingo to the cell surface. Disregulation of trafficking correlates with mistargeting of the tumor suppressor protein Discs large involved in epithelial polarity determination. Garz-depleted salivary cells are smaller and lack well-defined plasma membrane domains. Garz depletion also inhibits normal elongation and positioning of epithelial cells, resulting in a disorganized salivary gland that lacks a well defined luminal duct. Our findings suggest that Garz is essential for establishment of epithelial structures and demonstrate an absolute requirement for Garz during Drosophila development.
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Affiliation(s)
- Tomasz Szul
- Department of Cell Biology; University of Alabama at Birmingham; Birmingham, AL USA
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Rajasekharan S, Rana J, Gulati S, Sharma SK, Gupta V, Gupta S. Predicting the host protein interactors of Chandipura virus using a structural similarity-based approach. Pathog Dis 2013; 69:29-35. [PMID: 23847124 DOI: 10.1111/2049-632x.12064] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 06/14/2013] [Accepted: 06/26/2013] [Indexed: 01/18/2023] Open
Abstract
Chandipura virus (CHPV), alike other pathogens, exploits the cellular infrastructure of their hosts through complex network of interactions for successful infection. CHPV being a recently emerged pediatric encephalitic virus, the mechanisms involved in the establishment of viral persistence are still ill defined. Because the protein interface between CHPV and its host provides one means by which the virus invades and seize control of their human host machinery, the authors in this study have employed computational methods to create a network of putative protein-protein interactions between CHPV and its human host to shed light on the hitherto less-known CHPV biology. On the basis of the 2105 potential interactions predicted among 1650 human proteins and the five proteins of CHPV, the authors decipher the probable mode by which the virus manipulates the biological pathways of its host toward its own end and replicates while evading the immune system. Identification of such conserved set of putative interactions that allow the virus to take control of the host has the potential to deepen our understanding of the virus-specific remodeling processes of the host cell and illuminate new arenas of disease intervention.
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Affiliation(s)
- Sreejith Rajasekharan
- Center for Emerging Diseases, Department of Biotechnology, Jaypee Institute of Information Technology, Noida, Uttar Pradesh, India
| | - Jyoti Rana
- Center for Emerging Diseases, Department of Biotechnology, Jaypee Institute of Information Technology, Noida, Uttar Pradesh, India
| | - Sahil Gulati
- Center for Emerging Diseases, Department of Biotechnology, Jaypee Institute of Information Technology, Noida, Uttar Pradesh, India
| | - Sanjeev K Sharma
- Center for Emerging Diseases, Department of Biotechnology, Jaypee Institute of Information Technology, Noida, Uttar Pradesh, India
| | - Vandana Gupta
- Department of Microbiology, Ram Lal Anand College, University of Delhi South Campus (UDSC), Benito Juarez Marg, New Delhi, India
| | - Sanjay Gupta
- Center for Emerging Diseases, Department of Biotechnology, Jaypee Institute of Information Technology, Noida, Uttar Pradesh, India
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Martínez-Alonso E, Tomás M, Martínez-Menárguez JA. Golgi tubules: their structure, formation and role in intra-Golgi transport. Histochem Cell Biol 2013; 140:327-39. [PMID: 23812035 DOI: 10.1007/s00418-013-1114-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/16/2013] [Indexed: 11/28/2022]
Abstract
Tubules are common Golgi elements that can form extensive networks associated with the cis-, lateral and trans-Golgi sides, but despite this, they have almost been forgotten for decades. The molecular mechanisms involved in their formation, elongation and fission are only just beginning to be understood. However, the role of these membranes is not well understood. In the present review, we analyze the mechanisms that induce Golgi tubulation or, conversely, disrupt tubules in order to throw some lights on the nature of these elements. The putative role of these elements in the framework of current models for intra-Golgi transport is also discussed.
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Affiliation(s)
- Emma Martínez-Alonso
- Department of Cell Biology and Histology, Medical School, University of Murcia, 30100 Murcia, Spain
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Ackema KB, Sauder U, Solinger JA, Spang A. The ArfGEF GBF-1 Is Required for ER Structure, Secretion and Endocytic Transport in C. elegans. PLoS One 2013; 8:e67076. [PMID: 23840591 PMCID: PMC3686754 DOI: 10.1371/journal.pone.0067076] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 05/15/2013] [Indexed: 12/02/2022] Open
Abstract
Small GTPases of the Sar/Arf family are essential to generate transport containers that mediate communication between organelles of the secretory pathway. Guanine nucleotide exchange factor (GEFs) activate the small GTPases and help their anchorage in the membrane. Thus, GEFs in a way temporally and spatially control Sar1/Arf1 GTPase activation. We investigated the role of the ArfGEF GBF-1 in C. elegans oocytes and intestinal epithelial cells. GBF-1 localizes to the cis-Golgi and is part of the t-ER-Golgi elements. GBF-1 is required for secretion and Golgi integrity. In addition, gbf-1(RNAi) causes the ER reticular structure to become dispersed, without destroying ER exit sites (ERES) because the ERES protein SEC-16 was still localized in distinct punctae at t-ER-Golgi units. Moreover, GBF-1 plays a role in receptor-mediated endocytosis in oocytes, without affecting recycling pathways. We find that both the yolk receptor RME-2 and the recycling endosome-associated RAB-11 localize similarly in control and gbf-1(RNAi) oocytes. While RAB5-positive early endosomes appear to be less prominent and the RAB-5 levels are reduced by gbf-1(RNAi) in the intestine, RAB-7-positive late endosomes were more abundant and formed aggregates and tubular structures. Our data suggest a role for GBF-1 in ER structure and endosomal traffic.
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Affiliation(s)
- Karin B. Ackema
- Growth and Development, Biozentrum, University of Basel, Basel, Switzerland
| | - Ursula Sauder
- Microscopy Center, Biozentrum, University of Basel, Basel, Switzerland
| | - Jachen A. Solinger
- Growth and Development, Biozentrum, University of Basel, Basel, Switzerland
| | - Anne Spang
- Growth and Development, Biozentrum, University of Basel, Basel, Switzerland
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Abstract
The Golgi complex is considered the central station of the secretory pathway where cargo proteins and lipids are properly modified, classified, packed into specific carriers and delivered to their final destinations. Early electron microscope studies showed the extraordinary structural complexity of this organelle. However, despite the large volume of incoming and outgoing traffic, it is able to maintain its architecture, although it is also flexible enough to adapt to the functional status of the cell. Many components of the molecular machinery involved in membrane traffic and other Golgi functions have been identified. However, some basic aspects of Golgi functioning remain unsolved. For instance, how cargo moves through the stack remains controversial and two classical models have been proposed: vesicular transport and cisternal maturation. Since neither of these models explains all the experimental data, a combination of these models as well as new models have been proposed. In this context, the specific role of the cisternae, vesicles and tubules needs to be clarified. In this review, we summarize our current knowledge of the Golgi organization and function, focusing on the mechanisms of intra-Golgi transport.
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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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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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Bouvet S, Golinelli-Cohen MP, Contremoulins V, Jackson CL. Targeting of the Arf-GEF GBF1 to lipid droplets and Golgi membranes. J Cell Sci 2013; 126:4794-805. [DOI: 10.1242/jcs.134254] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Lipid droplet metabolism and secretory pathway trafficking both require activation of the Arf1 small G protein. The spatio-temporal regulation of Arf1 activation is mediated by guanine nucleotide exchange factors (GEFs) of the GBF and BIG families, but the mechanisms of their localization to multiple sites within cells are poorly understood. Here we show that GBF1 has a lipid-binding domain (HDS1) immediately downstream of the catalytic Sec7 domain, which mediates association with both lipid droplets and Golgi membranes in cells, and with bilayer liposomes and artificial droplets in vitro. An amphipathic helix within HDS1 is necessary and sufficient for lipid binding, both in vitro and in cells. The HDS1 domain of GBF1 is stably associated with lipid droplets in cells, and the catalytic Sec7 domain inhibits this potent lipid droplet binding capacity. Additional sequences upstream of the Sec7 domain-HDS1 tandem are required for localization to Golgi membranes. This mechanism provides insight into crosstalk between lipid droplet function and secretory trafficking.
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Marie M, Dale HA, Kouprina N, Saraste J. Division of the intermediate compartment at the onset of mitosis provides a mechanism for Golgi inheritance. J Cell Sci 2012; 125:5403-16. [PMID: 22946056 DOI: 10.1242/jcs.108100] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
As mammalian cells prepare for mitosis, the Golgi ribbon is first unlinked into its constituent stacks and then transformed into spindle-associated, pleiomorphic membrane clusters in a process that remains enigmatic. Also, it remains unclear whether Golgi inheritance involves the incorporation of Golgi enzymes into a pool of coat protein I (COPI) vesicles, or their COPI-independent transfer to the endoplasmic reticulum (ER). Based on the observation that the intermediate compartment (IC) at the ER-Golgi boundary is connected to the centrosome, we examined its mitotic fate and possible role in Golgi breakdown. The use of multiple imaging techniques and markers revealed that the IC elements persist during the M phase, maintain their compositional and structural properties and remain associated with the mitotic spindle, forming circular arrays at the spindle poles. At G2/M transition, the movement of the pericentrosomal domain of the IC (pcIC) to the cell centre and its expansion coincide with the unlinking of the Golgi ribbon. At prophase, coupled to centrosome separation, the pcIC divides together with recycling endosomes, providing novel landmarks for mitotic entry. We provide evidence that the permanent IC elements function as way stations during the COPI-dependent dispersal of Golgi components at prometa- and metaphase, indicating that they correspond to the previously described Golgi clusters. In addition, they continue to communicate with the vesicular 'Golgi haze' and thus are likely to provide templates for Golgi reassembly. These results implicate the IC in mitotic Golgi inheritance, resulting in a model that integrates key features of the two previously proposed pathways.
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Affiliation(s)
- Michaël Marie
- Department of Biomedicine and Molecular Imaging Center, University of Bergen, Jonas Lies Vei 91, N-5009 Bergen, Norway
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Armbruster K, Luschnig S. The Drosophila Sec7 domain guanine nucleotide exchange factor protein Gartenzwerg localizes at the cis-Golgi and is essential for epithelial tube expansion. J Cell Sci 2012; 125:1318-28. [PMID: 22349697 DOI: 10.1242/jcs.096263] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Protein trafficking through the secretory pathway plays a key role in epithelial organ development and function. The expansion of tracheal tubes in Drosophila depends on trafficking of coatomer protein complex I (COPI)-coated vesicles between the Golgi complex and the endoplasmic reticulum (ER). However, it is not clear how this pathway is regulated. Here we describe an essential function of the Sec7 domain guanine nucleotide exchange factor (GEF) gartenzwerg (garz) in epithelial tube morphogenesis and protein secretion. garz is essential for the recruitment of COPI components and for normal Golgi organization. A GFP-Garz fusion protein is distributed in the cytoplasm and accumulates at the cis-Golgi. Localization to the Golgi requires the C-terminal part of Garz. Conversely, blocking the GDP-GTP nucleotide exchange reaction leads to constitutive Golgi localization, suggesting that Garz cycles in a GEF-activity-dependent manner between cytoplasmic and Golgi-membrane-localized pools. The related human ARF-GEF protein GBF1 can substitute for garz function in Drosophila tracheal cells, indicating that the relevant functions of these proteins are conserved. We show that garz interacts genetically with the ARF1 homolog ARF79F and with the ARF1-GAP homolog Gap69C, thus placing garz in a regulatory circuit that controls COPI trafficking in Drosophila. Interestingly, overexpression of garz causes accumulation of secreted proteins in the ER, suggesting that excessive garz activity leads to increased retrograde trafficking. Thus, garz might regulate epithelial tube morphogenesis and secretion by controlling the rate of trafficking of COPI vesicles.
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Affiliation(s)
- Kristina Armbruster
- Institute of Molecular Life Sciences, University of Zurich, CH-8057 Zurich, Switzerland
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