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Wu Y, Bai Y, McEwan DG, Bentley L, Aravani D, Cox RD. Palmitoylated small GTPase ARL15 is translocated within Golgi network during adipogenesis. Biol Open 2021; 10:273707. [PMID: 34779483 PMCID: PMC8689486 DOI: 10.1242/bio.058420] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 11/10/2021] [Indexed: 11/20/2022] Open
Abstract
The small GTPase ARF family member ARL15 gene locus is associated in population studies with increased risk of type 2 diabetes, lower adiponectin and higher fasting insulin levels. Previously, loss of ARL15 was shown to reduce insulin secretion in a human β-cell line and loss-of-function mutations are found in some lipodystrophy patients. We set out to understand the role of ARL15 in adipogenesis and showed that endogenous ARL15 palmitoylated and localised in the Golgi of mouse liver. Adipocyte overexpression of palmitoylation-deficient ARL15 resulted in redistribution to the cytoplasm and a mild reduction in expression of some adipogenesis-related genes. Further investigation of the localisation of ARL15 during differentiation of a human white adipocyte cell line showed that ARL15 was predominantly co-localised with a marker of the cis face of Golgi at the preadipocyte stage and then translocated to other Golgi compartments after differentiation was induced. Finally, co-immunoprecipitation and mass spectrometry identified potential interacting partners of ARL15, including the ER-localised protein ARL6IP5. Together, these results suggest a palmitoylation dependent trafficking-related role of ARL15 as a regulator of adipocyte differentiation via ARL6IP5 interaction. This article has an associated First Person interview with the first author of the paper. Summary: ARL15 (GTPase ARF family) is associated with adipose traits. ARL15 is palmitoylated, localised to Golgi in preadipocytes and translocated to other Golgi compartments during differentiation. ARL15 interacts with ER-localised ARL6IP5.
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Affiliation(s)
- Yixing Wu
- Mammalian Genetics Unit, MRC Harwell Institute, Harwell Oxford, Oxfordshire, OX11 0RD, UK
| | - Ying Bai
- Mammalian Genetics Unit, MRC Harwell Institute, Harwell Oxford, Oxfordshire, OX11 0RD, UK
| | - David G McEwan
- Division of Cell Signalling & Immunology, School of Life Sciences, University of Dundee, Dundee, UK.,Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
| | - Liz Bentley
- Mammalian Genetics Unit, MRC Harwell Institute, Harwell Oxford, Oxfordshire, OX11 0RD, UK
| | - Dimitra Aravani
- Mammalian Genetics Unit, MRC Harwell Institute, Harwell Oxford, Oxfordshire, OX11 0RD, UK
| | - Roger D Cox
- Mammalian Genetics Unit, MRC Harwell Institute, Harwell Oxford, Oxfordshire, OX11 0RD, UK
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2
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Feng H, Cheng H, Hsiao T, Lin T, Hsu J, Huang L, Yu C. ArfGAP1 acts as a GTPase‐activating protein for human ADP‐ribosylation factor‐like 1 protein. FASEB J 2021; 35:e21337. [DOI: 10.1096/fj.202000818rr] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 12/13/2020] [Accepted: 12/17/2020] [Indexed: 01/08/2023]
Affiliation(s)
- Hsiang‐Pu Feng
- Graduate Institute of Biomedical Sciences, College of Medicine Chang Gung University Taoyuan Taiwan
| | - Hsiao‐Yun Cheng
- Department of Cell and Molecular Biology, College of Medicine Chang Gung University Taoyuan Taiwan
| | - Ting‐Feng Hsiao
- Graduate Institute of Biomedical Sciences, College of Medicine Chang Gung University Taoyuan Taiwan
| | - Tai‐Wei Lin
- Graduate Institute of Biomedical Sciences, College of Medicine Chang Gung University Taoyuan Taiwan
| | - Jia‐Wei Hsu
- Institute of Molecular Medicine, College of Medicine National Taiwan University Taipei Taiwan
- Institute of Biochemical Sciences, College of Life Science National Taiwan University Taipei Taiwan
| | - Lien‐Hung Huang
- Graduate Institute of Biomedical Sciences, College of Medicine Chang Gung University Taoyuan Taiwan
- Department of Neurosurgery Kaohsiung Chang Gung Memorial Hospital Kaohsiung Taiwan
| | - Chia‐Jung Yu
- Graduate Institute of Biomedical Sciences, College of Medicine Chang Gung University Taoyuan Taiwan
- Department of Cell and Molecular Biology, College of Medicine Chang Gung University Taoyuan Taiwan
- Department of Thoracic Medicine Chang Gung Memorial Hospital Taoyuan Taiwan
- Molecular Medicine Research Center Chang Gung University Taoyuan Taiwan
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3
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Intracellular Group A Streptococcus Induces Golgi Fragmentation To Impair Host Defenses through Streptolysin O and NAD-Glycohydrolase. mBio 2021; 12:mBio.01974-20. [PMID: 33563838 PMCID: PMC7885101 DOI: 10.1128/mbio.01974-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Group A Streptococcus (GAS; Streptococcus pyogenes) is a major human pathogen that causes streptococcal pharyngitis, skin and soft tissue infections, and life-threatening conditions such as streptococcal toxic-shock syndrome. During infection, GAS not only invades diverse host cells but also injects effector proteins such as NAD-glycohydrolase (Nga) into the host cells through a streptolysin O (SLO)-dependent mechanism without invading the cells; Nga and SLO are two major virulence factors that are associated with increased bacterial virulence. Here, we have shown that the invading GAS induces fragmentation of the Golgi complex and inhibits anterograde transport in the infected host cells through the secreted toxins SLO and Nga. GAS infection-induced Golgi fragmentation required both bacterial invasion and SLO-mediated Nga translocation into the host cytosol. The cellular Golgi network is critical for the sorting of surface molecules and is thus essential for the integrity of the epithelial barrier and for the immune response of macrophages to pathogens. In epithelial cells, inhibition of anterograde trafficking by invading GAS and Nga resulted in the redistribution of E-cadherin to the cytosol and an increase in bacterial translocation across the epithelial barrier. Moreover, in macrophages, interleukin-8 secretion in response to GAS infection was found to be suppressed by intracellular GAS and Nga. Our findings reveal a previously undescribed bacterial invasion-dependent function of Nga as well as a previously unrecognized GAS-host interaction that is associated with GAS pathogenesis.IMPORTANCE Two prominent virulence factors of group A Streptococcus (GAS), streptolysin O (SLO) and NAD-glycohydrolase (Nga), are linked to enhanced pathogenicity of the prevalent GAS strains. Recent advances show that SLO and Nga are important for intracellular survival of GAS in epithelial cells and macrophages. Here, we found that invading GAS disrupts the Golgi complex in host cells through SLO and Nga. We show that GAS-induced Golgi fragmentation requires bacterial invasion into host cells, SLO pore formation activity, and Nga NADase activity. GAS-induced Golgi fragmentation results in the impairment of the epithelial barrier and chemokine secretion in macrophages. This immune inhibition property of SLO and Nga by intracellular GAS indicates that the invasion of GAS is associated with virulence exerted by SLO and Nga.
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Patiño-Medina JA, Valle-Maldonado MI, Maldonado-Herrera G, Pérez-Arques C, Jácome-Galarza IE, Díaz-Pérez C, Díaz-Pérez AL, Araiza-Cervantes CA, Villagomez-Castro JC, Campos-García J, Ramírez-Díaz MI, Garre V, Meza-Carmen V. Role of Arf-like proteins (Arl1 and Arl2) of Mucor circinelloides in virulence and antifungal susceptibility. Fungal Genet Biol 2019; 129:40-51. [DOI: 10.1016/j.fgb.2019.04.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 04/17/2019] [Accepted: 04/19/2019] [Indexed: 10/27/2022]
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5
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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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6
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Abstract
ADP-ribosylation factors (Arfs) and ADP-ribosylation factor-like proteins (Arls) are highly conserved small GTPases that function as main regulators of vesicular trafficking and cytoskeletal reorganization. Arl1, the first identified member of the large Arl family, is an important regulator of Golgi complex structure and function in organisms ranging from yeast to mammals. Together with its effectors, Arl1 has been shown to be involved in several cellular processes, including endosomal trans-Golgi network and secretory trafficking, lipid droplet and salivary granule formation, innate immunity and neuronal development, stress tolerance, as well as the response of the unfolded protein. In this Commentary, we provide a comprehensive summary of the Arl1-dependent cellular functions and a detailed characterization of several Arl1 effectors. We propose that involvement of Arl1 in these diverse cellular functions reflects the fact that Arl1 is activated at several late-Golgi sites, corresponding to specific molecular complexes that respond to and integrate multiple signals. We also provide insight into how the GTP-GDP cycle of Arl1 is regulated, and highlight a newly discovered mechanism that controls the sophisticated regulation of Arl1 activity at the Golgi complex.
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Affiliation(s)
- Chia-Jung Yu
- Department of Cell and Molecular Biology, College of Medicine, Chang Gung University, Linkou, Tao-Yuan 33302, Taiwan.,Department of Thoracic Medicine, Chang Gung Memorial Hospital, Linkou, Tao-Yuan 33305, Taiwan
| | - Fang-Jen S Lee
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan .,Department of Medical Research, National Taiwan University Hospital, Taipei 10002, Taiwan
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7
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Ito Y, Toyooka K, Fujimoto M, Ueda T, Uemura T, Nakano A. The trans-Golgi Network and the Golgi Stacks Behave Independently During Regeneration After Brefeldin A Treatment in Tobacco BY-2 Cells. PLANT & CELL PHYSIOLOGY 2017; 58:811-821. [PMID: 28339924 DOI: 10.1093/pcp/pcx028] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Accepted: 02/10/2017] [Indexed: 06/06/2023]
Abstract
The trans-Golgi network (TGN) plays an essential role in intracellular membrane trafficking. In plant cells, recent live-cell imaging studies have revealed the dynamic behavior of the TGN independent from the Golgi apparatus. In order to better understand the relationships between the two organelles, we examined their dynamic responses to the reagent brefeldin A (BFA) and their recovery after BFA removal. Golgi markers responded to BFA similarly over a range of concentrations, whereas the behavior of the TGN was BFA concentration dependent. The TGN formed aggregates at high concentrations of BFA; however, TGN proteins relocalized to numerous small vesicular structures dispersed throughout the cytoplasm at lower BFA concentrations. During recovery from weak BFA treatment, the TGN started to regenerate earlier than the completion of the Golgi. The regeneration of the two organelles proceeded independently of each other for a while, and eventually was completed by their association. Our data suggest that there is some degree of autonomy for the regeneration of the TGN and the Golgi in tobacco BY-2 cells.
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Affiliation(s)
- Yoko Ito
- Live Cell Super-Resolution Imaging Research Team, RIKEN Center for Advanced Photonics, Wako, Saitama, Japan
| | - Kiminori Toyooka
- Mass Spectrometry and Microscopy Unit, Technology Platform Division, RIKEN Center for Sustainable Resource Science, Tsurumi-ku, Yokohama, Kanagawa, Japan
| | - Masaru Fujimoto
- Laboratory of Plant Molecular Genetics, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Takashi Ueda
- Division of Cellular Dynamics, National Institute for Basic Biology, Okazaki, Aichi, Japan
- Department of Basic Biology, Graduate University for Advanced Studies, Okazaki, Aichi, Japan
- Japan Science and Technology Agency (JST), PRESTO, Kawaguchi, Saitama, Japan
| | - Tomohiro Uemura
- Laboratory of Developmental Cell Biology, Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Akihiko Nakano
- Live Cell Super-Resolution Imaging Research Team, RIKEN Center for Advanced Photonics, Wako, Saitama, Japan
- Laboratory of Developmental Cell Biology, Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
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8
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Hierro A, Gershlick DC, Rojas AL, Bonifacino JS. Formation of Tubulovesicular Carriers from Endosomes and Their Fusion to the trans-Golgi Network. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 318:159-202. [PMID: 26315886 DOI: 10.1016/bs.ircmb.2015.05.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Endosomes undergo extensive spatiotemporal rearrangements as proteins and lipids flux through them in a series of fusion and fission events. These controlled changes enable the concentration of cargo for eventual degradation while ensuring the proper recycling of other components. A growing body of studies has now defined multiple recycling pathways from endosomes to the trans-Golgi network (TGN) which differ in their molecular machineries. The recycling process requires specific sets of lipids, coats, adaptors, and accessory proteins that coordinate cargo selection with membrane deformation and its association with the cytoskeleton. Specific tethering factors and SNARE (SNAP (Soluble NSF Attachment Protein) Receptor) complexes are then required for the docking and fusion with the acceptor membrane. Herein, we summarize some of the current knowledge of the machineries that govern the retrograde transport from endosomes to the TGN.
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Affiliation(s)
- Aitor Hierro
- Structural Biology Unit, CIC bioGUNE, Derio, Spain; IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - David C Gershlick
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | | | - Juan S Bonifacino
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
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9
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Ranjan P, Kashyap RS, Goel M, Veetil SK, Kateriya S. Cellular organelles facilitate dimerization of a newly identified Arf from Chlamydomonas reinhardtii. JOURNAL OF PHYCOLOGY 2014; 50:1137-1145. [PMID: 26988793 DOI: 10.1111/jpy.12245] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 08/22/2014] [Indexed: 06/05/2023]
Abstract
GTPases of the Ras superfamily regulate a wide variety of cellular processes including vesicular transport and various secretory pathways of the cell. ADP - ribosylation factor (ARF) belongs to one of the five major families of the Ras superfamily and serves as an important component of vesicle formation and transport machinery of the cells. The binding of GTP to these Arfs and its subsequent hydrolysis, induces conformational changes in these proteins leading to their enzymatic activities. The dimeric form of Arf is associated with membrane pinch-off during vesicle formation. In this report, we have identified an arf gene from the unicellular green alga Chlamydomonas reinhardtii, CrArf, and showed that the oligomeric state of the protein in C. renhardtii is modulated by the cellular membrane environment of the organism. Protein cross-linking experiments showed that the purified recombinant CrArf has the ability to form a dimer. Both the 20-kDa monomeric and 40-kDa dimeric forms of CrArf were recognized from Chlamydomonas total cell lysate (CrTLC) and purified recombinant CrArf by the CrArf specific antibody. The membranous environment of the cell appeared to facilitate dimerization of the CrArf, as dimeric form was found exclusively associated with the membrane bound organelles. The subcellular localization studies in Chlamydomonas suggested that CrArf mainly localized in the cytosol and was mislocalized in vesicle transport machinery inhibitor treated cells. This research sheds light on the importance of the cellular membrane environment for regulating the oligomeric state of CrArf protein in this organism and associated functional role.
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Affiliation(s)
- Peeyush Ranjan
- Department of Biochemistry, University of Delhi, South Campus, Benito Juarez Road, New Delhi, 110021, India
| | - Rudra Shankar Kashyap
- Department of Biochemistry, University of Delhi, South Campus, Benito Juarez Road, New Delhi, 110021, India
| | - Manisha Goel
- Department of Biophysics, University of Delhi, South Campus, Benito Juarez Road, New Delhi, 110021, India
| | - Sindhu Kandoth Veetil
- Department of Biochemistry, University of Delhi, South Campus, Benito Juarez Road, New Delhi, 110021, India
| | - Suneel Kateriya
- Department of Biochemistry, University of Delhi, South Campus, Benito Juarez Road, New Delhi, 110021, India
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10
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Abstract
The ARF-like (ARL) proteins, within the ARF family, are a collection of functionally diverse GTPases that share extensive (>40 %) identity with the ARFs and each other and are assumed to share basic mechanisms of regulation and a very incompletely documented degree of overlapping regulators. At least four ARLs were already present in the last eukaryotic common ancestor, along with one ARF, and these have been expanded to >20 members in mammals. We know little about the majority of these proteins so our review will focus on those about which the most is known, including ARL1, ARL2, ARL3, ARL4s, ARL6, ARL13s, and ARFRP1. From this fragmentary information we extract some generalizations and conclusions regarding the sources and extent of specificity and functions of the ARLs.
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Affiliation(s)
- Alfred Wittinghofer
- Max-Planck-Institute of Molecular Physiology, Dortmund, Nordrhein-Westfalen Germany
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11
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Chen KY, Tsai PC, Liu YW, Lee FJS. Competition between the golgin Imh1p and the GAP Gcs1p stabilizes activated Arl1p at the late-Golgi. J Cell Sci 2012; 125:4586-96. [PMID: 22767516 DOI: 10.1242/jcs.107797] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Golgins play diverse roles in regulating the structure and function of the Golgi. The yeast golgin Imh1p is targeted to the trans-Golgi network (TGN) through interaction of its GRIP domain with GTP-bound Arl1p. Recycling of Arl1p and Imh1p to the cytosol requires the hydrolysis of GTP bound to Arl1p; however, the point at which GTP hydrolysis occurs remains unknown. Here, we report that self-interaction of Imh1p plays a role in modulating spatial inactivation of Arl1p. Deletion of IMH1 in yeast decreases the amount of the GTP-bound Arl1p and results in less Arl1p residing on the TGN. Biochemically, purified Imh1p competes with Gcs1p, an Arl1p GTPase-activating protein (GAP), for binding to Arl1p, thus interfering with the GAP activity of Gcs1p toward Arl1p. Furthermore, we demonstrate that the self-interaction of Imh1p attenuates the Gcs1p-dependent GTP hydrolysis of Arl1p. Thus, we propose that the golgin Imh1p serves as a feedback regulator to modulate the GTP hydrolysis of Arl1p.
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Affiliation(s)
- Kuan-Yu Chen
- Institute of Molecular Medicine, College of Medicine, National Taiwan University and Department of Medical Research, National Taiwan University Hospital, Taipei 100, Taiwan
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12
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Manlandro CMA, Palanivel VR, Schorr EB, Mihatov N, Antony AA, Rosenwald AG. Mon2 is a negative regulator of the monomeric G protein, Arl1. FEMS Yeast Res 2012; 12:637-50. [PMID: 22594927 DOI: 10.1111/j.1567-1364.2012.00814.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Revised: 04/27/2012] [Accepted: 05/11/2012] [Indexed: 11/30/2022] Open
Abstract
Using site-directed mutants of ARL1 predicted to alter nucleotide binding, we examined phenotypes associated with the loss of ARL1 , including effects on membrane traffic and K (+) homeostasis. The GTP-restricted allele, ARL[Q72L] , complemented the membrane traffic phenotype (CPY secretion), but not the K (+) homeostasis phenotypes (sensitivity to hygromycin B, steady-state levels of K (+) , and accumulation of (86) Rb (+) ), while the XTP-restricted mutant, ARL1[D130N] , complemented the ion phenotypes, but not the membrane traffic phenotype. A GDP-restricted allele, ARL1[T32N] , did not effectively complement either phenotype. These results are consistent with a model in which Arl1 has three different conformations in vivo. We also explored the relationship between ARL1 and MON2 using the synthetic lethal phenotype exhibited by these two genes and demonstrated that MON2 is a negative regulator of the GTP-restricted allele of ARL1 , ARL1[Q72L] . Finally, we constructed several new alleles predicted to alter binding of Arl1 to the sole GRIP domain containing protein in yeast, Imh1, and found that ARL1[F52G] and ARL1[Y82G] were unable to complement the loss of ARL1 with respect to either the membrane traffic or K (+) homeostasis phenotypes. Our study expands understanding of the roles of Arl1 in vivo.
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13
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Houghton FJ, Bellingham SA, Hill AF, Bourges D, Ang DK, Gemetzis T, Gasnereau I, Gleeson PA. Arl5b is a Golgi-localised small G protein involved in the regulation of retrograde transport. Exp Cell Res 2012; 318:464-77. [DOI: 10.1016/j.yexcr.2011.12.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Revised: 12/04/2011] [Accepted: 12/28/2011] [Indexed: 11/30/2022]
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14
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Christis C, Munro S. The small G protein Arl1 directs the trans-Golgi-specific targeting of the Arf1 exchange factors BIG1 and BIG2. ACTA ACUST UNITED AC 2012; 196:327-35. [PMID: 22291037 PMCID: PMC3275380 DOI: 10.1083/jcb.201107115] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Specificity in Arf1 GEF recruitment to the trans-Golgi, and thus in localized Arf1 activation, is provided by an Arf-like G protein. The small G protein Arf1 regulates Golgi traffic and is activated by two related types of guanine nucleotide exchange factor (GEF). GBF1 acts at the cis-Golgi, whereas BIG1 and its close paralog BIG2 act at the trans-Golgi. Peripheral membrane proteins such as these GEFs are often recruited to membranes by small G proteins, but the basis for specific recruitment of Arf GEFs, and hence Arfs, to Golgi membranes is not understood. In this paper, we report a liposome-based affinity purification method to identify effectors for small G proteins of the Arf family. We validate this with the Drosophila melanogaster Arf1 orthologue (Arf79F) and the related class II Arf (Arf102F), which showed a similar pattern of effector binding. Applying the method to the Arf-like G protein Arl1, we found that it binds directly to Sec71, the Drosophila ortholog of BIG1 and BIG2, via an N-terminal region. We show that in mammalian cells, Arl1 is necessary for Golgi recruitment of BIG1 and BIG2 but not GBF1. Thus, Arl1 acts to direct a trans-Golgi–specific Arf1 GEF, and hence active Arf1, to the trans side of the Golgi.
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Affiliation(s)
- Chantal Christis
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, England, UK
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15
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Identification of yeast genes involved in k homeostasis: loss of membrane traffic genes affects k uptake. G3-GENES GENOMES GENETICS 2011; 1:43-56. [PMID: 22384317 PMCID: PMC3276120 DOI: 10.1534/g3.111.000166] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 03/24/2011] [Indexed: 11/18/2022]
Abstract
Using the homozygous diploid Saccharomyces deletion collection, we searched for strains with defects in K(+) homeostasis. We identified 156 (of 4653 total) strains unable to grow in the presence of hygromycin B, a phenotype previously shown to be indicative of ion defects. The most abundant group was that with deletions of genes known to encode membrane traffic regulators. Nearly 80% of these membrane traffic defective strains showed defects in uptake of the K(+) homolog, (86)Rb(+). Since Trk1, a plasma membrane protein localized to lipid microdomains, is the major K(+) influx transporter, we examined the subcellular localization and Triton-X 100 insolubility of Trk1 in 29 of the traffic mutants. However, few of these showed defects in the steady state levels of Trk1, the localization of Trk1 to the plasma membrane, or the localization of Trk1 to lipid microdomains, and most defects were mild compared to wild-type. Three inositol kinase mutants were also identified, and in contrast, loss of these genes negatively affected Trk1 protein levels. In summary, this work reveals a nexus between K(+) homeostasis and membrane traffic, which does not involve traffic of the major influx transporter, Trk1.
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16
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Liao F, Wang L, Yang LB, Peng X, Sun M. NtGNL1 plays an essential role in pollen tube tip growth and orientation likely via regulation of post-Golgi trafficking. PLoS One 2010; 5:e13401. [PMID: 20976165 PMCID: PMC2955533 DOI: 10.1371/journal.pone.0013401] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Accepted: 09/19/2010] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Tobacco GNOM LIKE 1 (NtGNL1), a new member of the Big/GBF family, is characterized by a sec 7 domain. Thus, we proposed that NtGNL1 may function in regulating pollen tube growth for vesicle trafficking. METHODOLOGY/PRINCIPAL FINDINGS To test this hypothesis, we used an RNAi technique to down-regulate NtGNL1 expression and found that pollen tube growth and orientation were clearly inhibited. Cytological observations revealed that both timing and behavior of endocytosis was disrupted, and endosome trafficking to prevacuolar compartments (PVC) or multivesicular bodies (MVB) was altered in pollen tube tips. Moreover, NtGNL1 seemed to partially overlap with Golgi bodies, but clearly colocalized with putative late endosome compartments. We also observed that in such pollen tubes, the Golgi apparatus disassembled and fused with the endoplasmic reticulum, indicating abnormal post-Golgi trafficking. During this process, actin organization was also remodeled. CONCLUSIONS/SIGNIFICANCE Thus, we revealed that NtGNL1 is essential for pollen tube growth and orientation and it likely functions via stabilizing the structure of the Golgi apparatus and ensuring post-Golgi trafficking.
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Affiliation(s)
- Fanglei Liao
- Key Laboratory of Ministry of Education for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan, China
- College of Chemistry and Life Science, Zhejiang Normal University, Jinhua, China
| | - Lu Wang
- Key Laboratory of Ministry of Education for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan, China
- Biotechnology Department, Tobacco Research Institute of Chinese Academy of Agricultural Sciences, Qingdao, China
| | - Li-Bo Yang
- Key Laboratory of Ministry of Education for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Xiongbo Peng
- Key Laboratory of Ministry of Education for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Mengxiang Sun
- Key Laboratory of Ministry of Education for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan, China
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17
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Chen KY, Tsai PC, Hsu JW, Hsu HC, Fang CY, Chang LC, Tsai YT, Yu CJ, Lee FJS. Syt1p promotes activation of Arl1p at the late Golgi to recruit Imh1p. J Cell Sci 2010; 123:3478-89. [PMID: 20841378 DOI: 10.1242/jcs.074237] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In yeast, Arl3p recruits Arl1p GTPase to regulate Golgi function and structure. However, the molecular mechanism involved in regulating activation of Arl1p at the Golgi is unknown. Here, we show that Syt1p promoted activation of Arl1p and recruitment of a golgin protein, Imh1p, to the Golgi. Deletion of SYT1 resulted in the majority of Arl1p being distributed diffusely throughout the cytosol. Overexpression of Syt1p increased Arl1p-GTP production in vivo and the Syt1-Sec7 domain promoted nucleotide exchange on Arl1p in vitro. Syt1p function required the N-terminal region, Sec7 and PH domains. Arl1p, but not Arl3p, interacted with Syt1p. Localization of Syt1p to the Golgi did not require Arl3p. Unlike arl1Δ or arl3Δ mutants, syt1Δ did not show defects in Gas1p transport, cell wall integrity or vacuolar structure. These findings reveal that activation of Arl1p is regulated in part by Syt1p, and imply that Arl1p activation, by using more than one GEF, exerts distinct biological activities at the Golgi compartment.
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Affiliation(s)
- Kuan-Yu Chen
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, and Department of Medical Research, National Taiwan University Hospital, Taipei 100, Taiwan
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18
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Wei S, Xu Y, Shi H, Wong SH, Han W, Talbot K, Hong W, Ong WY. EHD1 is a synaptic protein that modulates exocytosis through binding to snapin. Mol Cell Neurosci 2010; 45:418-29. [PMID: 20696250 DOI: 10.1016/j.mcn.2010.07.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Revised: 06/29/2010] [Accepted: 07/28/2010] [Indexed: 12/30/2022] Open
Abstract
EHD1 is an EH (Eps15 homology) domain-containing protein involved in endosomal recycling. Our yeast two hybrid screening experiments showed that EHD1 interacts with a synaptic protein, snapin, and the present study was carried out to further elucidate the functional significance of this interaction. Immunoreactivity to EHD1 is observed in the cerebral cortex, hippocampus and striatum, in the rat brain. The protein is colocalized with the axon terminal marker synaptophysin in cultured neurons. EHD1 binds to the C terminus of snapin via its C terminus EH domain. It negatively affects the binding of a SNARE complex protein, SNAP-25, to snapin, probably due to the competition for overlapping binding sites on the C terminus of snapin. EHD1 affects the coupling of synaptotagmin-1 to the SNARE complex, and could be a negative regulator of exocytosis. This is supported by electrophysiological findings that PC-12 cells which overexpress EHD1 show reduced depolarization-induced exocytosis compared to controls, but the reduced exocytosis is not observed in cells which overexpress the N terminus of EHD1 that is unable to bind snapin. Together, the above results indicate that EHD1 is a synaptic protein that negatively affects exocytosis through binding to snapin.
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Affiliation(s)
- Shunhui Wei
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, A*STAR, Singapore 138667, Singapore
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19
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Toward a model for Arf GTPases as regulators of traffic at the Golgi. FEBS Lett 2009; 583:3872-9. [PMID: 19879269 DOI: 10.1016/j.febslet.2009.10.066] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Revised: 10/25/2009] [Accepted: 10/26/2009] [Indexed: 12/19/2022]
Abstract
In this review, I summarize the likely roles played by ADP-ribosylation factor (Arf) proteins in the regulation of membrane traffic at the Golgi, from the perspective of the GTPase. The most glaring limitations to the development of a coherent molecular model are highlighted; including incomplete information on the initiation of Arf activation, identification of the "accessory proteins" required for carrier maturation and scission, and those required for directed traffic and fusion at the destination membrane. Though incomplete, the molecular model of carrier biogenesis has developed rapidly in recent years and promises richness in understanding this essential process.
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20
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Zahn C, Jaschke A, Weiske J, Hommel A, Hesse D, Augustin R, Lu L, Hong W, Florian S, Scheepers A, Joost HG, Huber O, Schürmann A. ADP-ribosylation Factor-like GTPase ARFRP1 Is Required for Trans-Golgi to Plasma Membrane Trafficking of E-cadherin. J Biol Chem 2008; 283:27179-88. [DOI: 10.1074/jbc.m802108200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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21
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Dejgaard SY, Murshid A, Erman A, Kızılay O, Verbich D, Lodge R, Dejgaard K, Ly-Hartig TBN, Pepperkok R, Simpson JC, Presley JF. Rab18 and Rab43 have key roles in ER-Golgi trafficking. J Cell Sci 2008; 121:2768-81. [DOI: 10.1242/jcs.021808] [Citation(s) in RCA: 139] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Rabs and Arfs/Arls are Ras-related small GTPases of particular relevance to membrane trafficking. It is thought that these proteins regulate specific pathways through interactions with coat, motor, tether and SNARE proteins. We screened a comprehensive list of Arf/Arl/Rab proteins, previously identified on purified Golgi membranes by a proteomics approach (37 in total), for Golgi or intra-Golgi localization, dominant-negative and overexpression phenotypes. Further analysis of two of these proteins, Rab18 and Rab43, strongly indicated roles in ER-Golgi trafficking. Rab43-T32N redistributed Golgi elements to ER exit sites without blocking trafficking of the secretory marker VSVG-GFP from ER to cell surface. Wild-type Rab43 redistributes the p150Glued subunit of dynactin, consistent with a specific role in regulating association of pre-Golgi intermediates with microtubules. Overexpression of wild-type GFP-Rab18 or incubation with any of three siRNAs directed against Rab18 severely disrupts the Golgi complex and reduces secretion of VSVG. Rab18 mutants specifically enhance retrograde Golgi-ER transport of the COPI-independent cargo β-1,4-galactosyltransferase (Galtase)-YFP but not the COPI-dependent cargo p58-YFP from the Golgi to ER in a photobleach assay. Rab18-S22N also potentiated brefeldin-A-induced ER-Golgi fusion. This study is the first comprehensive application of large-scale proteomics to the cell biology of small GTPases of the secretory pathway.
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Affiliation(s)
- Selma Y. Dejgaard
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada, H3A 2B2
| | - Ayesha Murshid
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada, H3A 2B2
| | - Ayşegül Erman
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada, H3A 2B2
| | - Özge Kızılay
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada, H3A 2B2
| | - David Verbich
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada, H3A 2B2
| | - Robert Lodge
- Laboratoire d'Immunoretrovirologie, Centre de Recherche d'Infectiologie – CHUL, Quebec, Canada, G1V 4G2
| | - Kurt Dejgaard
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada, H3G 1Y6
| | | | - Rainer Pepperkok
- Cell Biology and Biophysics Unit, EMBL, 69117 Heidelberg, Germany
| | | | - John F. Presley
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada, H3A 2B2
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22
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Sahin A, Espiau B, Tetaud E, Cuvillier A, Lartigue L, Ambit A, Robinson DR, Merlin G. The leishmania ARL-1 and Golgi traffic. PLoS One 2008; 3:e1620. [PMID: 18286177 PMCID: PMC2237903 DOI: 10.1371/journal.pone.0001620] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2007] [Accepted: 01/19/2008] [Indexed: 12/20/2022] Open
Abstract
We present here the characterisation of the Leishmania small G protein ADP-Ribosylation Factor-Like protein 1 (ARL-1). The ARL-1 gene is present in one copy per haploid genome and conserved among trypanosomatids. It encodes a protein of 20 kDa, which is equally expressed in the insect promastigote and mammalian amastigote forms of the parasite. ARL-1 localises to the Trans-Golgi Network (TGN); N-terminal myristoylation is essential for TGN localisation. In vivo expression of the LdARL-1/Q74L and LdARL-1/T51N mutants (GTP- and GDP-bound blocked forms respectively) shows that GDP/GTP cycling occurs entirely within the TGN. This is contrary to previous reports in yeast and mammals, where the mutant empty form devoid of nucleotide has been considered as the GDP-blocked form. The dominant-negative empty form mutant LdARL-1/T34N inhibits endocytosis and intracellular trafficking from the TGN to the Lysosome/Multivesicular Tubule and to the acidocalcisomes; these defects are probably related to a mislocalisation of the GRIP domain-containing vesicle tethering factors which cannot be recruited to the TGN by the cytoplasmic LdARL-1/T34N. Thus, besides the functional characterization of a new mutant and a better understanding of ARL-1 GDP/GTP cycling, this work shows that Leishmania ARL-1 is a key component of an essential pathway worth future study.
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Affiliation(s)
- Annelise Sahin
- Laboratoire de Microbiologie Cellulaire et Moléculaire et Pathogénicité, UMR CNRS 5234, Université Bordeaux 2, Bordeaux, France
| | - Benoît Espiau
- Laboratoire de Microbiologie Cellulaire et Moléculaire et Pathogénicité, UMR CNRS 5234, Université Bordeaux 2, Bordeaux, France
| | - Emmanuel Tetaud
- Laboratoire de Microbiologie Cellulaire et Moléculaire et Pathogénicité, UMR CNRS 5234, Université Bordeaux 2, Bordeaux, France
| | - Armelle Cuvillier
- Laboratoire de Microbiologie Cellulaire et Moléculaire et Pathogénicité, UMR CNRS 5234, Université Bordeaux 2, Bordeaux, France
| | - Lydia Lartigue
- Laboratoire de Microbiologie Cellulaire et Moléculaire et Pathogénicité, UMR CNRS 5234, Université Bordeaux 2, Bordeaux, France
| | - Audrey Ambit
- Laboratoire de Microbiologie Cellulaire et Moléculaire et Pathogénicité, UMR CNRS 5234, Université Bordeaux 2, Bordeaux, France
| | - Derrick R. Robinson
- Laboratoire de Microbiologie Cellulaire et Moléculaire et Pathogénicité, UMR CNRS 5234, Université Bordeaux 2, Bordeaux, France
| | - Gilles Merlin
- Laboratoire de Microbiologie Cellulaire et Moléculaire et Pathogénicité, UMR CNRS 5234, Université Bordeaux 2, Bordeaux, France
- *E-mail:
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23
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Derby MC, Lieu ZZ, Brown D, Stow JL, Goud B, Gleeson PA. The trans-Golgi Network Golgin, GCC185, is Required for Endosome-to-Golgi Transport and Maintenance of Golgi Structure. Traffic 2007; 8:758-73. [PMID: 17488291 DOI: 10.1111/j.1600-0854.2007.00563.x] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Four mammalian golgins are specifically targeted to the trans-Golgi network (TGN) membranes via their C-terminal GRIP domains. The TGN golgins, p230/golgin-245 and golgin-97, are recruited via the GTPase Arl1, whereas the TGN golgin GCC185 is recruited independently of Arl1. Here we show that GCC185 is localized to a region of the TGN distinct from Arl1 and plays an essential role in maintaining the organization of the Golgi apparatus. Using both small interfering RNA (siRNA) and microRNA (miRNA), we show that depletion of GCC185 in HeLa cells frequently resulted in fragmentation of the Golgi apparatus. Golgi apparatus fragments were dispersed throughout the cytoplasm and contained both cis and trans markers. Trafficking of anterograde and retrograde cargo was analysed over an extended period following GCC185 depletion. Early effects of GCC185 depletion included a perturbation in the distribution of the mannose-6-phosphate receptor and a block in shiga toxin trafficking to the Golgi apparatus, which occurred in parallel with the fragmentation of the Golgi ribbon. Internalized shiga toxin accumulated in Rab11-positive endosomes, indicating GCC185 is essential for transport between the recycling endosome and the TGN. In contrast, the plasma membrane-TGN recycling protein TGN38 was efficiently transported into GCC185-depleted Golgi apparatus fragments throughout a 96-h period, and anterograde transport of E-cadherin was functional until a late stage of GCC185 depletion. This study demonstrated (i) a more effective long-term depletion of GCC185 using miRNA than siRNA and (ii) a dual role for the GCC185 golgin in the regulation of endosome-to-TGN membrane transport and in the organization of the Golgi apparatus.
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Affiliation(s)
- Merran C Derby
- Department of Biochemistry and Molecular Biology, University of Melbourne, Melbourne, Victoria 3010, Australia, and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Victoria 3010, Australia
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24
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Zahn C, Hommel A, Lu L, Hong W, Walther DJ, Florian S, Joost HG, Schürmann A. Knockout of Arfrp1 leads to disruption of ARF-like1 (ARL1) targeting to the trans-Golgi in mouse embryos and HeLa cells. Mol Membr Biol 2007; 23:475-85. [PMID: 17127620 DOI: 10.1080/09687860600840100] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
ADP-ribosylation factor related protein 1 (ARFRP1) is a member of the ARF-family of GTPases which operate as molecular switches in the regulation of intracellular protein traffic. Deletion of the mouse Arfrp1 gene leads to embryonic lethality during early gastrulation, suggesting that ARFRP1 is required for cell adhesion-related processes. Here we show that ARFRP1 specifically controls targeting of ARL1 and its effector Golgin-245 to the trans-Golgi. GTP-bound ARFRP1 (ARFRP1-Q79L mutant) is associated with Golgi membranes and co-localized with the GTPase ARL1. In contrast, the guanine nucleotide exchange defective ARFRP1 mutant (ARFRP1-T31N) clusters within the cytosol. ARFRP1-T31N or depletion of endogenous ARFRP1 by RNA interference disrupts the Golgi association of ARL1 and of the GRIP-domain protein Golgin-245 and alters the distribution of a trans-Golgi network marker, syntaxin 6. In contrast, the targeting of two other Golgi-associated proteins, GM130 and giantin, was unaffected. Furthermore, in Arfrp1-/ - embryos ARL1 dislocated from Golgi membranes whereas it was associated with intracellular membranes in wild-type embryos. These data suggest that lethality of Arfrp1 knockout embryos is due to a specific disruption of protein targeting, e.g., of ARL1 and Golgin-245, to the Golgi.
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Affiliation(s)
- Claudia Zahn
- Department of Pharmacology, German Institute of Human Nutrition Potsdam-Rehbruecke, Nuthetal, Germany
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25
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Derby MC, Gleeson PA. New Insights into Membrane Trafficking and Protein Sorting. INTERNATIONAL REVIEW OF CYTOLOGY 2007; 261:47-116. [PMID: 17560280 DOI: 10.1016/s0074-7696(07)61002-x] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Protein transport in the secretory and endocytic pathways is a multistep process involving the generation of transport carriers loaded with defined sets of cargo, the shipment of the cargo-loaded transport carriers between compartments, and the specific fusion of these transport carriers with a target membrane. The regulation of these membrane-mediated processes involves a complex array of protein and lipid interactions. As the machinery and regulatory processes of membrane trafficking have been defined, it is increasingly apparent that membrane transport is intimately connected with a number of other cellular processes, such as quality control in the endoplasmic reticulum (ER), cytoskeletal dynamics, receptor signaling, and mitosis. The fidelity of membrane trafficking relies on the correct assembly of components on organelles. Recruitment of peripheral proteins plays a critical role in defining organelle identity and the establishment of membrane subdomains, essential for the regulation of vesicle transport. The molecular mechanisms for the biogenesis of membrane subdomains are also central to understanding how cargo is sorted and segregated and how different populations of transport carriers are generated. In this review we will focus on the emerging themes of organelle identity, membrane subdomains, regulation of Golgi trafficking, and advances in dissecting pathways in physiological systems.
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Affiliation(s)
- Merran C Derby
- Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Victoria 3010, Australia
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26
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Alzhanova D, Hruby DE. A trans-Golgi network resident protein, golgin-97, accumulates in viral factories and incorporates into virions during poxvirus infection. J Virol 2006; 80:11520-7. [PMID: 16987983 PMCID: PMC1642589 DOI: 10.1128/jvi.00287-06] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Poxviruses are the only DNA viruses known to replicate and assemble in the cytoplasm of infected cells. Poxvirus morphogenesis is a complicated process in which four distinct infectious forms of the virus are produced: intracellular mature virus, intracellular enveloped virus, cell-associated enveloped virus, and extracellular enveloped virus. The source of primary membrane wrapping the intracellular mature virus, the first infectious form, is still unknown. Although the membrane was suggested to originate from the endoplasmic reticulum-Golgi intermediate compartment, none of the marker proteins from this or any other cell compartments has been found in the intracellular mature virus. Thus, it was hypothesized that the membrane is either extensively modified by the virus or synthesized de novo. In the work described here, we demonstrate that a host cell protein residing in the trans-Golgi network membrane, golgin-97, is transported to the sites of virus replication and assembly and becomes incorporated into the virions during poxvirus infection. Inside the virion, golgin-97 is associated with the insoluble core protein fraction. Being able to adopt a long rod-like structure, the protein apparently extends through the virion envelope and protrudes from its surface. Here we discuss the potential role and functions of golgin-97 in poxvirus replication and propose two working models.
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Affiliation(s)
- Dina Alzhanova
- Oregon State University, Department of Microbiology, 220 Nash Hall, Corvallis, OR 97331-3804, USA
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27
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Stefano G, Renna L, Hanton SL, Chatre L, Haas TA, Brandizzi F. ARL1 plays a role in the binding of the GRIP domain of a peripheral matrix protein to the Golgi apparatus in plant cells. PLANT MOLECULAR BIOLOGY 2006; 61:431-49. [PMID: 16830178 DOI: 10.1007/s11103-006-0022-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2005] [Accepted: 02/02/2006] [Indexed: 05/10/2023]
Abstract
ARF GTPases play a central role in regulating membrane dynamics and protein transport in eukaryotic cells. ARF-like (ARL) proteins are close relatives of the ARF regulators of vesicular transport, but their function in plant cells is poorly characterized. Here, by means of live cell imaging and site-directed mutagenesis, we have investigated the cellular function of the plant GTPase ARL1. We provide direct evidence for a role of this ARL family member in the association of a plant golgin with the plant Golgi apparatus. Our data reveal the existence of key residues within the conserved GRIP-domain of the golgin and within the GTPase ARL1 that are central to ARL1-GRIP interaction. Mutations of these residues abolish the interaction of GRIP with the GTP-bound ARL1 and induce a redistribution of GRIP into the cytosol. This indicates that the localization of GRIP to the Golgi apparatus is strongly influenced by the interaction of GRIP with Golgi-localized ARL1. Our results assign a cellular role to a member of the Arabidopsis ARL family in the plant secretory pathway and propose mechanisms for localization of peripheral golgins to the plant Golgi apparatus.
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Affiliation(s)
- Giovanni Stefano
- Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, S7N 5E2, SK, Canada
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28
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Kahn RA, Cherfils J, Elias M, Lovering RC, Munro S, Schurmann A. Nomenclature for the human Arf family of GTP-binding proteins: ARF, ARL, and SAR proteins. ACTA ACUST UNITED AC 2006; 172:645-50. [PMID: 16505163 PMCID: PMC2063696 DOI: 10.1083/jcb.200512057] [Citation(s) in RCA: 203] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Ras superfamily is comprised of at least four large families of regulatory guanosine triphosphate-binding proteins, including the Arfs. The Arf family includes three different groups of proteins: the Arfs, Arf-like (Arls), and SARs. Several Arf family members have been very highly conserved throughout eukaryotic evolution and have orthologues in evolutionally diverse species. The different means by which Arf family members have been identified have resulted in an inconsistent and confusing array of names. This confusion is further compounded by differences in nomenclature between different species. We propose a more consistent nomenclature for the human members of the Arf family that may also serve as a guide for nomenclature in other species.
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Affiliation(s)
- Richard A Kahn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA.
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29
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Abstract
Coiled-coil and multisubunit tethers have emerged as key regulators of membrane traffic and organellar architecture. The restricted subcellular localization of tethers and their ability to interact with Rabs and soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) suggests that tethers participate in determining the specificity of membrane fusion. An accepted model of tether function considers them molecular “bridges” that link opposing membranes before SNARE pairing. This model has been extended by findings in various experimental systems, suggesting that tethers may have other functions. Recent reports implicate tethers in the assembly of SNARE complexes, cargo selection and transit, cytoskeletal events, and localized attachment of regulatory proteins. A concept of tethers as scaffolding machines that recruit protein components involved in varied cellular responses is emerging. In this model, tethers function as integration switches that simultaneously transmit information to coordinate distinct processes required for membrane traffic.
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Affiliation(s)
- Elizabeth Sztul
- Dept. of Cell Biology, Univ. of Alabama at Birmingham, 1918 Univ. Blvd., Birmingham, AL 35294, USA.
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30
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Abstract
Small GTP-binding proteins of the Rab and Arf (ADP-ribosylation factor) families play a central role in the membrane trafficking pathways of eukaryotic cells. The prototypical members of the Arf family are Arf1-Arf6 and Sar1, which have well-characterized roles in membrane traffic or cytoskeletal reorganization. However, eukaryotic genomes encode additional proteins, which share the characteristic structural features of the Arf family, but the role of these 'Arf-like' (Arl) proteins is less well understood. This review discusses Arl1, a GTPase that is widely conserved in evolution, and which is localized to the Golgi in all species so far examined. The best-characterized effectors of Arl1 are coiled-coil proteins which share a C-terminal GRIP domain, but other apparent effectors include the GARP (Golgi-associated retrograde protein)/VFT (Vps fifty-three) vesicle-tethering complex and Arfaptin 2. As least some of these proteins are believed to have a role in membrane traffic. Genetic analysis in a number of species has shown that Arl1 is not essential for exocytosis, but rather suggest that it is required for traffic from endosomes to the Golgi.
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Affiliation(s)
- S Munro
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK.
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31
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Shin HW, Kobayashi H, Kitamura M, Waguri S, Suganuma T, Uchiyama Y, Nakayama K. Roles of ARFRP1 (ADP-ribosylation factor-related protein 1) in post-Golgi membrane trafficking. J Cell Sci 2005; 118:4039-48. [PMID: 16129887 DOI: 10.1242/jcs.02524] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
ADP-ribosylation factor (ARF)-related protein 1 (ARFRP1) is a small GTPase with significant similarity to the ARF family. However, little is known about the function of ARFRP1 in mammalian cells, although knockout mice of its gene are embryonic lethal. In the present study, we demonstrate that ARFRP1 is associated mainly with the trans-Golgi compartment and the trans-Golgi network (TGN) and is an essential regulatory factor for targeting of Arl1 and GRIP domain-containing proteins, golgin-97 and golgin-245, onto Golgi membranes. Furthermore, we show that, in concert with Arl1 and GRIP proteins, ARFRP1 is implicated in the Golgi-to-plasma membrane transport of the vesicular stomatitis virus G protein as well as in the retrograde transport of TGN38 and Shiga toxin from endosomes to the TGN.
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Affiliation(s)
- Hye-Won Shin
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
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32
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Wang ZX, Shi L, Liu JF, An XM, Chang WR, Liang DC. 2.0 A crystal structure of human ARL5-GDP3'P, a novel member of the small GTP-binding proteins. Biochem Biophys Res Commun 2005; 332:640-5. [PMID: 15896705 DOI: 10.1016/j.bbrc.2005.04.168] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2005] [Accepted: 04/29/2005] [Indexed: 10/25/2022]
Abstract
ARL5 is a member of ARLs, which is widespread in high eukaryotes and homologous between species. But no structure or biological function of this member is reported. We expressed, purified, and resolved the structure of human ARL5 with bound GDP3'P at 2.0 A resolution. A comparison with the known structures of ARFs shows that besides the typical features of ARFs, human ARL5 has specific features of its own. Bacterially expressed human ARL5 contains bound GDP3'P which is seldom seen in other structures. The hydrophobic tail of the introduced detergent Triton X-305 binds at the possible myristoylation site of Gly2, simulating the myristoylated state of N-terminal amphipathic helix in vivo. The structural features of the nucleotide binding motifs and the switch regions prove that ARL5 will undergo the typical GDP/GTP structural cycle as other members of ARLs, which is the basis of their biological functions.
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Affiliation(s)
- Zhan-Xin Wang
- National Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, PR China
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Liu YW, Huang CF, Huang KB, Lee FJS. Role for Gcs1p in regulation of Arl1p at trans-Golgi compartments. Mol Biol Cell 2005; 16:4024-33. [PMID: 15975906 PMCID: PMC1196316 DOI: 10.1091/mbc.e05-01-0023] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
ADP-ribosylation factor (ARF) and ARF-like (ARL) proteins are members of the ARF family, which are critical components of several different vesicular trafficking pathways. ARFs have little or no detectable GTPase activity without the assistance of a GTPase-activating protein (GAP). Here, we demonstrate that yeast Gcs1p exhibits GAP activity toward Arl1p and Arf1p in vitro, and Arl1p can interact with Gcs1p in a GTP-dependent manner. Arl1p was observed both on trans-Golgi and in cytosol and was recruited from cytosol to membranes in a GTP-dependent manner. In gcs1 mutant cells, the fraction of Arl1p in cytosol relative to trans-Golgi was less than it was in wild-type cells. Increasing Gcs1p levels returned the distribution toward that of wild-type cells. Both Arl1p and Gcs1p influenced the distribution of Imh1p, an Arl1p effector. Our data are consistent with the conclusion that Arl1p moves in a dynamic equilibrium between trans-Golgi and cytosol, and the release of Arl1p from membranes in cells requires the hydrolysis of bound GTP, which is accelerated by Gcs1p.
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Affiliation(s)
- Ya-Wen Liu
- Institute of Molecular Medicine, College of Medicine, and Department of Medical Research, National Taiwan University Hospital, National Taiwan University, Taipei 100, Taiwan
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34
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Donaldson JG, Honda A, Weigert R. Multiple activities for Arf1 at the Golgi complex. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2005; 1744:364-73. [PMID: 15979507 DOI: 10.1016/j.bbamcr.2005.03.001] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 12/23/2004] [Revised: 02/28/2005] [Accepted: 03/01/2005] [Indexed: 10/25/2022]
Abstract
The Arf family of GTPases regulates membrane traffic and organelle structure. At the Golgi complex, Arf proteins facilitate membrane recruitment of many cytoplasmic coat proteins to allow sorting of membrane proteins for transport, stimulate the activity of enzymes that modulate the lipid composition of the Golgi, and assemble a cytoskeletal scaffold on the Golgi. Arf1 is the Arf family member most closely studied for its function at the Golgi complex. A number of regulators that activate and inactivate Arf1 on the Golgi have been described that localize to different regions of the organelle. This spatial distribution of Arf regulators may facilitate the recruitment of the coat proteins and other Arf effectors to different regions of the Golgi complex.
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Affiliation(s)
- Julie G Donaldson
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Building 50, Room 2503, Bethesda, MD 20892, USA.
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Loh E, Peter F, Subramaniam VN, Hong W. Mammalian Bet3 functions as a cytosolic factor participating in transport from the ER to the Golgi apparatus. J Cell Sci 2005; 118:1209-22. [PMID: 15728249 DOI: 10.1242/jcs.01723] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The TRAPP complex identified in yeast regulates vesicular transport in the early secretory pathway. Although some components of the TRAPP complex are structurally conserved in mammalian cells, the function of the mammalian components has not been examined. We describe our biochemical and functional analysis of mammalian Bet3, the most conserved component of the TRAPP complex. Bet3 mRNA is ubiquitously expressed in all tissues. Antibodies raised against recombinant Bet3 specifically recognize a protein of 22 kDa. In contrast to yeast Bet3p, the majority of Bet3 is present in the cytosol. To investigate the possible involvement of Bet3 in transport events in mammalian cells, we utilized a semi-intact cell system that reconstitutes the transport of the envelope glycoprotein of vesicular stomatitis virus (VSV-G) from the ER to the Golgi apparatus. In this system, antibodies against Bet3 inhibit transport in a dose-dependent manner, and cytosol that is immunodepleted of Bet3 is also defective in this transport. This defect can be rescued by supplementing the Bet3-depleted cytosol with recombinant GST-Bet3. We also show that Bet3 acts after COPII but before Rab1, alpha-SNAP and the EGTA-sensitive stage during ER-Golgi transport. Gel filtration analysis demonstrates that Bet3 exists in two distinct pools in the cytosol, the high-molecular-weight pool may represent the TRAPP complex, whereas the other probably represents the monomeric Bet3.
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Affiliation(s)
- Eva Loh
- Membrane Biology Laboratory, Institute of Molecular and Cell Biology, 61 Biopolis Drive, Singapore 138673, Republic of Singapore
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36
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Price HP, Panethymitaki C, Goulding D, Smith DF. Functional analysis of TbARL1, an N-myristoylated Golgi protein essential for viability in bloodstream trypanosomes. J Cell Sci 2005; 118:831-41. [PMID: 15687105 PMCID: PMC2705012 DOI: 10.1242/jcs.01624] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Myristoyl-CoA:protein N-myristoyltransferase (NMT), an essential protein in Trypanosoma brucei and Leishmania major, catalyses the covalent attachment of the fatty acid myristate to the N-terminus of a range of target proteins. In order to define the essential targets contributing to lethality in the absence of NMT activity, we have focused on the ADP-ribosylation factor (Arf) family of GTP-binding proteins, as growth arrest in Saccharomyces cerevisiae mutants with reduced NMT activity correlates with a decrease in N-myristoylated Arf proteins. We have identified nine Arf/Arls in the T. brucei and T. cruzi genomes and ten in L. major. Characterization of the T. brucei ARL1 homologue has revealed that the protein is localized in the Golgi apparatus and is expressed only in the mammalian bloodstream form of the parasite and not in the insect procyclic stage. This is the only reported example to date of a differentially expressed ARL1 homologue in any species. We have used RNA interference to demonstrate that ARL1 is essential for viability in T. brucei bloodstream parasites. Prior to cell death, depletion of ARL1 protein in bloodstream parasites results in abnormal morphology, including disintegration of the Golgi structure, multiple flagella and nuclei, and the presence of large numbers of vesicles. The cells have only a minor apparent defect in endocytosis but exocytosis of variant surface glycoprotein to the parasite surface is significantly delayed. RNA interference of ARL1 in procyclic cells has no effect on parasite growth or morphology. Our results suggest that there may be different pathways regulating Golgi structure and function in the two major life cycle stages of T. brucei.
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37
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Munson AM, Haydon DH, Love SL, Fell GL, Palanivel VR, Rosenwald AG. Yeast ARL1 encodes a regulator of K+ influx. J Cell Sci 2005; 117:2309-20. [PMID: 15126631 DOI: 10.1242/jcs.01050] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A molecular genetic approach was undertaken in Saccharomyces cerevisiae to examine the functions of ARL1, encoding a G protein of the Ras superfamily. We show here that ARL1 is an important component of the control of intracellular K(+). The arl1 mutant was sensitive to toxic cations, including hygromycin B and other aminoglycoside antibiotics, tetramethylammonium ions, methylammonium ions and protons. The hygromycin-B-sensitive phenotype was suppressed by the inclusion of K(+) and complemented by wild-type ARL1 and an allele of ARL1 predicted to be unbound to nucleotide in vivo. The arl1 mutant strain internalized approximately 25% more [(14)C]-methylammonium ion than did the wild type, consistent with hyperpolarization of the plasma membrane. The arl1 strain took up 30-40% less (86)Rb(+) than did the wild type, showing an inability to regulate K(+) import properly, contributing to membrane hyperpolarity. By contrast, K(+) and H(+) efflux were undisturbed. The loss of ARL1 had no effect on the steady-state level or the localization of a tagged version of Trk1p. High copy suppressors of the hygromycin-B phenotype included SAP155, encoding a protein that interacts with the cell cycle regulator Sit4p, and HAL4 and HAL5, encoding Ser/Thr kinases that regulate the K(+)-influx mediators Trk1p and Trk2p. These results are consistent with a model in which ARL1, via regulation of HAL4/HAL5, governs K(+) homeostasis in cells.
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Affiliation(s)
- Amanda M Munson
- Department of Biology, 406 Reiss Science Center, Box 571229, Georgetown University, Washington, DC 20057, USA
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38
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Lu L, Tai G, Hong W. Interaction of Arl1 GTPase with the GRIP domain of Golgin-245 as assessed by GST (glutathione-S-transferase) pull-down experiments. Methods Enzymol 2005; 404:432-41. [PMID: 16413289 DOI: 10.1016/s0076-6879(05)04038-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Arl1 is a member of the Arf/Arl family of Ras-like GTPase superfamily. Arl1 is enriched in the trans-Golgi network (TGN). We have recently shown that Arl1 regulates TGN recruitment of GRIP domain-containing Golgin-97 and Golgin-245 by interacting with the conserved GRIP domain present in their carboxyl (C)-termini. We describe here methods for the analysis of the interaction between Arl1(GTP) and the GRIP domain of Golgin-245 using in vitro GST pull-down experiments. GST-Arl1(GTP) can recover endogenous Golgin-245 from HeLa cell cytosol. Furthermore, GST-GRIP domain of Golgin-245 can efficiently retain endogenous active Arl1. A pull-down assay is developed to quantify the relative level of active Arl1.
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Affiliation(s)
- Lei Lu
- Membrane Biology Laboratory, Institute of Molecular and Cell Biology, Singapore
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39
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Ambasudhan R, Wang X, Jablonski MM, Thompson DA, Lagali PS, Wong PW, Sieving PA, Ayyagari R. Atrophic macular degeneration mutations in ELOVL4 result in the intracellular misrouting of the protein. Genomics 2004; 83:615-25. [PMID: 15028284 DOI: 10.1016/j.ygeno.2003.10.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2003] [Accepted: 10/07/2003] [Indexed: 11/20/2022]
Abstract
Elongation of very long chain fatty acids 4 (ELOVL4) is a novel member of the ELO family of genes that are involved in fatty acid metabolism. ELOVL4 encodes a putative transmembrane protein of 314 amino acids that carries a possible endoplasmic reticulum (ER) retention/retrieval signal (KXKXX) at the C-terminus. Two distinct mutations, a 5-bp deletion and a complex mutation from the same region in exon 6 of this gene, have been reported so far and are associated with autosomal dominant atrophic macular degeneration (adMD/STGD3). Both of these deletions could result in C-terminal truncation and loss of the ER retention signal in the mutant protein. We expressed the wild-type and mutant proteins in COS-7 and CHO cells to study the intracellular distribution of ELOVL4 and to identify possible implications of the above mutations in its localization. Immunofluorescence analysis of these proteins along with organelle marker antibodies revealed predominant ER localization for wild-type ELOVL4. Targeted deletion of the dilysine motif at the C-terminus of the protein resulted in the loss of ER localization. Immunoelectron microscopy and immunofluorescence analysis revealed a similar ER localization pattern for the protein in human photoreceptors. These data indicate that ELOVL4 is an ER-resident protein, which supports its suggested function in fatty acid elongation. We also demonstrate that the localization of both mutant proteins was dramatically changed from an ER to a Golgi distribution. Our observations suggest that the consequences of defective protein trafficking could underlie the molecular mechanism associated with degeneration of the macula in the patients with adMD/STGD3.
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Affiliation(s)
- Rajesh Ambasudhan
- Kellogg Eye Center, Ophthalmology, University of Michigan, 1000 Wall Street, Ann Arbor, MI 48105, USA
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40
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Lim KP, Hong W. Human Nischarin/imidazoline receptor antisera-selected protein is targeted to the endosomes by a combined action of a PX domain and a coiled-coil region. J Biol Chem 2004; 279:54770-82. [PMID: 15475348 DOI: 10.1074/jbc.m411315200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Around 50 mammalian and 15 yeast proteins are known to contain the phox (PX) domain, the majority (about 30) of which is classified as sorting nexins (SNXs). The PX domain, a hallmark of these proteins, is a conserved stretch of about 120 amino acids and is recently shown to mediate phosphoinositide binding. A few PX domain proteins (including some SNXs) have been shown to participate in diverse cellular processes such as protein sorting, signal transduction, and vesicle fusion. In this report, we present our results supporting a role of human IRAS to act as a SNX. The mouse homologue, previously identified as Nischarin, has been shown to interact with the alpha(5) subunit of integrin and inhibit cell migration (Alahari, S. K., Lee J. W., and Juliano R. L. (2000) J. Cell Biol. 51, 1141-1154). Its human homologue (imidazoline receptor antisera-selected (IRAS)), on the other hand, contains an NH(2)-terminal extension and is a larger protein of 1504 amino acids consisting of an NH(2)-terminal PX domain, 5 putative leucine-rich repeats, a predicted coiled-coil domain, and a long COOH-terminal region. We show that it has the ability to homo-oligomerize via its coiled-coil region. The PX domain of IRAS is essential for association with phosphatidylinositol 3-phosphate-enriched endosomal membranes. However, the PX domain of IRAS alone is insufficient for its localization to endosomes, unless the coiled-coil domain was included or it is artificially dimerized by glutathione S-transferase. Interaction of human IRAS with alpha(5) integrin is not affected by the NH(2)-terminal extension, and overexpression of IRAS could cause a redistribution of surface alpha(5) integrin to intracellular endosomal structures.
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Affiliation(s)
- Koh-Pang Lim
- Membrane Biology Laboratory, Institute of Molecular and Cell Biology, Proteos Building, 61 Biopolis Drive, Singapore 138673, Singapore
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41
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Lu L, Tai G, Hong W. Autoantigen Golgin-97, an effector of Arl1 GTPase, participates in traffic from the endosome to the trans-golgi network. Mol Biol Cell 2004; 15:4426-43. [PMID: 15269279 PMCID: PMC519138 DOI: 10.1091/mbc.e03-12-0872] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The precise cellular function of Arl1 and its effectors, the GRIP domain Golgins, is not resolved, despite our recent understanding that Arl1 regulates the membrane recruitment of these Golgins. In this report, we describe our functional study of Golgin-97. Using a Shiga toxin B fragment (STxB)-based in vitro transport assay, we demonstrated that Golgin-97 plays a role in transport from the endosome to the trans-Golgi network (TGN). The recombinant GRIP domain of Golgin-97 as well as antibodies against Golgin-97 inhibited the transport of STxB in vitro. Membrane-associated Golgin-97, but not its cytosolic pool, was required in the in vitro transport assay. The kinetic characterization of inhibition by anti-Golgin-97 antibody in comparison with anti-Syntaxin 16 antibody established that Golgin-97 acts before Syntaxin 16 in endosome-to-TGN transport. Knock down of Golgin-97 or Arl1 by their respective small interference RNAs (siRNAs) also significantly inhibited the transport of STxB to the Golgi in vivo. In siRNA-treated cells with reduced levels of Arl1, internalized STxB was instead distributed peripherally. Microinjection of Golgin-97 antibody led to the fragmentation of Golgi apparatus and the arrested transport to the Golgi of internalized Cholera toxin B fragment. We suggest that Golgin-97 may function as a tethering molecule in endosome-to-TGN retrograde traffic.
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Affiliation(s)
- Lei Lu
- Membrane Biology Laboratory, Institute of Molecular and Cell Biology, Singapore 138673, Singapore
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42
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Love SL, Manlandro CMA, Testa CJ, Thomas AE, Tryggestad KE, Rosenwald AG. The yeast genes, ARL1 and CCZ1, interact to control membrane traffic and ion homeostasis. Biochem Biophys Res Commun 2004; 319:840-6. [PMID: 15184059 DOI: 10.1016/j.bbrc.2004.05.063] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2004] [Indexed: 10/26/2022]
Abstract
The yeast ARL1 gene, encoding a guanine-nucleotide binding protein of the Arf-like family, exhibits a synthetic genetic interaction with CCZ1. An arl1 Delta ccz1 Delta double mutant was viable but grew slowly, was more sensitive to caffeine, Ca(2+), Zn(2+), and hygromycin B than either single mutant, and had a more severe vacuolar protein sorting phenotype. Overexpression of ARL1 did not suppress ccz1 Delta mutant phenotypes, nor did overexpression of CCZ1 suppress arl1 Delta mutant phenotypes. We conclude that ARL1 and CCZ1 independently contribute to both ion homeostasis and protein sorting.
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Affiliation(s)
- Sherie L Love
- Department of Biology, Georgetown University, Washington, DC 20057, USA
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43
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Abstract
Post-translational modification with myristoyl or prenyl groups is essential for membrane association of many small GTPases in the Ras superfamily. Two recent papers show that, rather than myristoylation, amino-terminal acetylation of the Arf-like protein Arl3p is required for Golgi targeting via an interaction with an integral membrane protein called Sys1.
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Affiliation(s)
- Todd R Graham
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235-1634, USA.
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44
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Abstract
The trans-Golgi network is the major sorting compartment of the secretory pathway for protein, lipid and membrane traffic. There is a constant flow of membrane and cargo to and from this compartment. Evidence is emerging that the trans-Golgi network has multiple biochemically and functionally distinct subdomains, each of which contributes to the combined sorting and transport requirements of this dynamic compartment. The recruitment of distinct arrays of protein complexes to trans-Golgi network membranes is likely to produce the diversity of structure and biochemistry observed amongst subdomains that serve to generate different carriers or maintain resident trans-Golgi network components. This review discusses how these subdomains may be formed and examines the molecular players involved, including G proteins, clathrin adaptors and golgin tethers. Diversity within these protein families is highlighted and shown to be critical for the functionality of the trans-Golgi network, as a mediator of protein sorting and membrane transport, and for the maintenance of Golgi structure.
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Affiliation(s)
- Paul A Gleeson
- The Russell Grimwade School of Biochemistry and Molecular Biology, The University of Melbourne, Melbourne, Victoria 3010, Australia.
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45
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Munson AM, Love SL, Shu J, Palanivel VR, Rosenwald AG. ARL1 participates with ATC1/LIC4 to regulate responses of yeast cells to ions. Biochem Biophys Res Commun 2004; 315:617-23. [PMID: 14975746 DOI: 10.1016/j.bbrc.2004.01.099] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2004] [Indexed: 10/26/2022]
Abstract
ATC1/LIC4, previously identified as a suppressor of the Li(+)-sensitive phenotype of calcineurin mutants, was also identified as a suppressor of the hygromycin B-sensitive phenotype of strains lacking the G protein gene, ARL1. Although loss of ARL1 confers several phenotypes, including sensitivity to hygromycin B and Li(+), reduced influx of K(+), and increased secretion of carboxypeptidase Y (CPY), loss of ATC1 was without effect by these and other measures. However, loss of ATC1 in an arl1 background exacerbated ion sensitivities, although not the CPY phenotype. Moreover, overexpression of ATC1 in an arl1 background partially suppressed ion sensitivities, but not the CPY phenotype. Additionally, expression of ENA1, the Na(+)/Li(+) efflux ATPase, and activated calcineurin, but not normal calcineurin, suppressed the Li(+)-sensitive phenotype of the arl1 atc1 double mutant. These results show ARL1 and ATC1 interact to control intracellular ion levels, but ATC1 has little influence on other functions of ARL1.
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Affiliation(s)
- Amanda M Munson
- Department of Biology, Georgetown University, Washington, DC 20057, USA
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46
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Wu M, Lu L, Hong W, Song H. Structural basis for recruitment of GRIP domain golgin-245 by small GTPase Arl1. Nat Struct Mol Biol 2003; 11:86-94. [PMID: 14718928 DOI: 10.1038/nsmb714] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2003] [Accepted: 11/20/2003] [Indexed: 11/08/2022]
Abstract
Recruitment of the GRIP domain golgins to the trans-Golgi network is mediated by Arl1, a member of the ARF/Arl small GTPase family, through interaction between their GRIP domains and Arl1-GTP. The crystal structure of Arl1-GTP in complex with the GRIP domain of golgin-245 shows that Arl1-GTP interacts with the GRIP domain predominantly in a hydrophobic manner, with the switch II region conferring the main recognition surface. The involvement of the switch and interswitch regions in the interaction between Arl1-GTP and GRIP accounts for the specificity of GRIP domain for Arl1-GTP. Mutations that abolished the Arl1-mediated Golgi localization of GRIP domain golgins have been mapped on the interface between Arl1-GTP and GRIP. Notably, the GRIP domain forms a homodimer in which each subunit interacts separately with one Arl1-GTP. Mutations disrupting the GRIP domain dimerization also abrogated its Golgi targeting, suggesting that the dimeric form of GRIP domain is a functional unit.
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Affiliation(s)
- Mousheng Wu
- Laboratory of Macromolecular Structure, Institute of Molecular and Cell Biology, 30 Medical Drive, Singapore 117609
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47
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Panic B, Perisic O, Veprintsev DB, Williams RL, Munro S. Structural basis for Arl1-dependent targeting of homodimeric GRIP domains to the Golgi apparatus. Mol Cell 2003; 12:863-74. [PMID: 14580338 DOI: 10.1016/s1097-2765(03)00356-3] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Golgins are large coiled-coil proteins that play a role in Golgi structure and vesicle traffic. The Arf-like GTPase Arl1 regulates the translocation of GRIP domain-containing golgins to Golgi membranes. We report here the 1.7 A resolution structure of human Arl1-GTP in a complex with the GRIP domain of golgin-245. The structure reveals that the GRIP domain consists of an S-shaped arrangement of three helices. The domain forms a homodimer that binds two Arl1-GTPs using two helices from each monomer. The structure is consistent with golgin-245 forming parallel coiled-coils and suggests how Arl1-GTP/GRIP complexes interact with Golgi membranes via the N termini of Arl1-GTP and the C-terminal tails of the GRIP domains. In cells, bivalent association with Arl1-GTP would increase residence time of the golgins on Golgi membranes. Despite no conservation of sequence, topology, or even helical direction, several other effectors form similar interactions with small GTPases via a pair of alpha helices, suggesting a common structural basis for effector recognition.
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Affiliation(s)
- Bojana Panic
- MRC Laboratory of Molecular Biology, MRC Centre, Hills Road, Cambridge CB2 2QH, United Kingdom
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48
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Lu L, Hong W. Interaction of Arl1-GTP with GRIP domains recruits autoantigens Golgin-97 and Golgin-245/p230 onto the Golgi. Mol Biol Cell 2003; 14:3767-81. [PMID: 12972563 PMCID: PMC196566 DOI: 10.1091/mbc.e03-01-0864] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
A cellular role and the mechanism of action for small GTPase Arl1 have been defined. Arl1-GTP interacts with the GRIP domains of Golgin-97 and Golgin-245, a process dependent on conserved residues of the GRIP domains that are important for Golgi targeting. The switch II region of Arl1 confers the specificity of this interaction. Arl1-GTP mediates Golgi recruitment of Golgin-97 in a switch II-dependent manner, whereas tethering Arl1-GTP onto endosomes can mediate endosomal targeting of Golgin-97. Golgin-97 and Golgin-245 are dissociated from the Golgi when Arl1 is knocked-down by its siRNA. Arl1-GTP thus functions to recruit Golgin-97 and Golgin-245 onto the Golgi via interacting with their GRIP domains.
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Affiliation(s)
- Lei Lu
- Membrane Biology Laboratory, Institute of Molecular and Cell Biology, Singapore 117609, Singapore
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49
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Gillingham AK, Munro S. Long coiled-coil proteins and membrane traffic. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1641:71-85. [PMID: 12914949 DOI: 10.1016/s0167-4889(03)00088-0] [Citation(s) in RCA: 175] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Protein transport between organelles is mediated by vesicles which must accurately dock and fuse with appropriate compartments. Over the past several years a large number of long coiled-coil proteins have been identified on the Golgi and on endosomes, mostly as auto-antigens in autoimmune disorders. Based on their restricted intracellular distributions and their predicted rod-like structure, these proteins have been proposed to play a role in tethering vesicles to target organelles prior to fusion. However, such proteins may also play a structural role, for example as components of a Golgi matrix, or as scaffolds for the assembly of other factors important for fusion. This review will examine what is known about the function of these large coiled-coil proteins in membrane traffic.
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50
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Panic B, Whyte JRC, Munro S. The ARF-like GTPases Arl1p and Arl3p act in a pathway that interacts with vesicle-tethering factors at the Golgi apparatus. Curr Biol 2003; 13:405-10. [PMID: 12620189 DOI: 10.1016/s0960-9822(03)00091-5] [Citation(s) in RCA: 154] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The ARLs are a diverse family of GTPases that are related to ADP-ribosylation factors (ARFs), but whose function is poorly understood. There are at least ten ARLs in humans, two of which have homologs in the yeast Saccharomyces cerevisiae (ARL1/Arl1p and ARFRP1/Arl3p). The function of ARFRP1 is unknown, but mammalian ARL1 has recently been found to interact with a number of effectors including the GRIP domain that is present in a family of Golgi-localized long coiled-coil proteins. We find that in yeast, the intracellular targeting of Imh1p, the only yeast GRIP domain protein, is dependent on both Arl1p and Arl3p, but not on the ARF proteins. A recombinant form of the Imh1p GRIP domain binds to Arl1p in a GTP-dependent manner, but not to Arl3p. Yeast also contain a relative of SCOCO, a protein proposed to bind human ARL1, but this yeast protein, Slo1p, appears to bind Arl3p rather than Arl1p in vitro. However, Imh1p is not the sole effector of Arl1p since affinity chromatography of cytosol with immobilized Arl1p:GTP revealed an interaction with the GARP/VFT complex that is thought to act in the tethering of vesicles to the Golgi apparatus. Finally, we find that Arl3p is required in vivo for the targeting of Arl1p, explaining its requirement for the normal distribution of Imh1p.
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Affiliation(s)
- Bojana Panic
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, United Kingdom
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