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Mechanisms regulating the sorting of soluble lysosomal proteins. Biosci Rep 2022; 42:231123. [PMID: 35394021 PMCID: PMC9109462 DOI: 10.1042/bsr20211856] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 04/05/2022] [Accepted: 04/07/2022] [Indexed: 11/17/2022] Open
Abstract
Lysosomes are key regulators of many fundamental cellular processes such as metabolism, autophagy, immune response, cell signalling and plasma membrane repair. These highly dynamic organelles are composed of various membrane and soluble proteins, which are essential for their proper functioning. The soluble proteins include numerous proteases, glycosidases and other hydrolases, along with activators, required for catabolism. The correct sorting of soluble lysosomal proteins is crucial to ensure the proper functioning of lysosomes and is achieved through the coordinated effort of many sorting receptors, resident ER and Golgi proteins, and several cytosolic components. Mutations in a number of proteins involved in sorting soluble proteins to lysosomes result in human disease. These can range from rare diseases such as lysosome storage disorders, to more prevalent ones, such as Alzheimer’s disease, Parkinson’s disease and others, including rare neurodegenerative diseases that affect children. In this review, we discuss the mechanisms that regulate the sorting of soluble proteins to lysosomes and highlight the effects of mutations in this pathway that cause human disease. More precisely, we will review the route taken by soluble lysosomal proteins from their translation into the ER, their maturation along the Golgi apparatus, and sorting at the trans-Golgi network. We will also highlight the effects of mutations in this pathway that cause human disease.
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2
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Makowski SL, Kuna RS, Field SJ. Induction of membrane curvature by proteins involved in Golgi trafficking. Adv Biol Regul 2019; 75:100661. [PMID: 31668661 PMCID: PMC7056495 DOI: 10.1016/j.jbior.2019.100661] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 09/25/2019] [Accepted: 09/30/2019] [Indexed: 12/22/2022]
Abstract
The Golgi apparatus serves a key role in processing and sorting lipids and proteins for delivery to their final cellular destinations. Vesicle exit from the Golgi initiates with directional deformation of the lipid bilayer to produce a bulge. Several mechanisms have been described by which lipids and proteins can induce directional membrane curvature to promote vesicle budding. Here we review some of the mechanisms implicated in inducing membrane curvature at the Golgi to promote vesicular trafficking to various cellular destinations.
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Affiliation(s)
- Stefanie L Makowski
- Department of Medicine, Division of Endocrinology and Metabolism, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Ramya S Kuna
- Department of Medicine, Division of Endocrinology and Metabolism, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Seth J Field
- Department of Medicine, Division of Endocrinology and Metabolism, University of California, San Diego, La Jolla, CA, 92093, USA.
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3
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Lopes-da-Silva M, McCormack JJ, Burden JJ, Harrison-Lavoie KJ, Ferraro F, Cutler DF. A GBF1-Dependent Mechanism for Environmentally Responsive Regulation of ER-Golgi Transport. Dev Cell 2019; 49:786-801.e6. [PMID: 31056345 PMCID: PMC6764485 DOI: 10.1016/j.devcel.2019.04.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 02/19/2019] [Accepted: 04/04/2019] [Indexed: 12/17/2022]
Abstract
How can anterograde membrane trafficking be modulated by physiological cues? A screen of Golgi-associated proteins revealed that the ARF-GEF GBF1 can selectively modulate the ER-Golgi trafficking of prohaemostatic von Willebrand factor (VWF) and extracellular matrix (ECM) proteins in human endothelial cells and in mouse fibroblasts. The relationship between levels of GBF1 and the trafficking of VWF into forming secretory granules confirmed GBF1 is a limiting factor in this process. Further, GBF1 activation by AMPK couples its control of anterograde trafficking to physiological cues; levels of glucose control GBF1 activation in turn modulating VWF trafficking into secretory granules. GBF1 modulates both ER and TGN exit, the latter dramatically affecting the size of the VWF storage organelles, thereby influencing the hemostatic capacity of the endothelium. The role of AMPK as a central integrating element of cellular pathways with intra- and extra-cellular cues can now be extended to modulation of the anterograde secretory pathway. The Arf-GEF GBF1 modulates anterograde trafficking of VWF and ECM proteins Loss of GBF1 slows ER and TGN exit, producing swollen ER and giant WPBs Activation of GBF1 via AMPK reduces endothelial WPB size and secretion Metabolic change alters anterograde trafficking and cargo secretion via AMPK-GBF1
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Affiliation(s)
- Mafalda Lopes-da-Silva
- Endothelial Cell Biology Laboratory, MRC Laboratory for Molecular Cell Biology, University College London, London, UK.
| | - Jessica J McCormack
- Endothelial Cell Biology Laboratory, MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Jemima J Burden
- Electron Microscopy Laboratory, MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Kimberly J Harrison-Lavoie
- Endothelial Cell Biology Laboratory, MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Francesco Ferraro
- Endothelial Cell Biology Laboratory, MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Daniel F Cutler
- Endothelial Cell Biology Laboratory, MRC Laboratory for Molecular Cell Biology, University College London, London, UK.
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4
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Alternative Splicing in Ca(V)2.2 Regulates Neuronal Trafficking via Adaptor Protein Complex-1 Adaptor Protein Motifs. J Neurosci 2016; 35:14636-52. [PMID: 26511252 DOI: 10.1523/jneurosci.3034-15.2015] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
N-type voltage-gated calcium (Ca(V)2.2) channels are expressed in neurons and targeted to the plasma membrane of presynaptic terminals, facilitating neurotransmitter release. Here, we find that the adaptor protein complex-1 (AP-1) mediates trafficking of Ca(V)2.2 from the trans-Golgi network to the cell surface. Examination of splice variants of Ca(V)2.2, containing either exon 37a (selectively expressed in nociceptors) or 37b in the proximal C terminus, reveal that canonical AP-1 binding motifs, YxxΦ and [DE]xxxL[LI], present only in exon 37a, enhance intracellular trafficking of exon 37a-containing Ca(V)2.2 to the axons and plasma membrane of rat DRG neurons. Finally, we identify differential effects of dopamine-2 receptor (D2R) and its agonist-induced activation on trafficking of Ca(V)2.2 isoforms. D2R slowed the endocytosis of Ca(V)2.2 containing exon 37b, but not exon 37a, and activation by the agonist quinpirole reversed the effect of the D2R. Our work thus reveals key mechanisms involved in the trafficking of N-type calcium channels.
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The ADP-ribosylation factor 1 gene is indispensable for mouse embryonic development after implantation. Biochem Biophys Res Commun 2014; 453:748-53. [DOI: 10.1016/j.bbrc.2014.10.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 10/03/2014] [Indexed: 11/24/2022]
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6
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Lang MJ, Martinez-Marquez JY, Prosser DC, Ganser LR, Buelto D, Wendland B, Duncan MC. Glucose starvation inhibits autophagy via vacuolar hydrolysis and induces plasma membrane internalization by down-regulating recycling. J Biol Chem 2014; 289:16736-47. [PMID: 24753258 DOI: 10.1074/jbc.m113.525782] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Cellular energy influences all aspects of cellular function. Although cells can adapt to a gradual reduction in energy, acute energy depletion poses a unique challenge. Because acute depletion hampers the transport of new energy sources into the cell, the cell must use endogenous substrates to replenish energy after acute depletion. In the yeast Saccharomyces cerevisiae, glucose starvation causes an acute depletion of intracellular energy that recovers during continued glucose starvation. However, how the cell replenishes energy during the early phase of glucose starvation is unknown. In this study, we investigated the role of pathways that deliver proteins and lipids to the vacuole during glucose starvation. We report that in response to glucose starvation, plasma membrane proteins are directed to the vacuole through reduced recycling at the endosomes. Furthermore, we found that vacuolar hydrolysis inhibits macroautophagy in a target of rapamycin complex 1-dependent manner. Accordingly, we found that endocytosis and hydrolysis are required for survival in glucose starvation, whereas macroautophagy is dispensable. Together, these results suggest that hydrolysis of components delivered to the vacuole independent of autophagy is the cell survival mechanism used by S. cerevisiae in response to glucose starvation.
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Affiliation(s)
- Michael J Lang
- From the Department of Cell and Developmental Biology, the University of Michigan, Ann Arbor, Michigan 48109
| | - Jorge Y Martinez-Marquez
- From the Department of Cell and Developmental Biology, the University of Michigan, Ann Arbor, Michigan 48109
| | - Derek C Prosser
- the Department of Biology, the Johns Hopkins University, Baltimore, Maryland 21218, and
| | - Laura R Ganser
- the Department of Biology, the University of North Carolina, Chapel Hill, North Carolina 27599
| | - Destiney Buelto
- the Curriculum in Genetics and Molecular Biology, the University of North Carolina, Chapel Hill, North Carolina 27599
| | - Beverly Wendland
- the Department of Biology, the Johns Hopkins University, Baltimore, Maryland 21218, and
| | - Mara C Duncan
- From the Department of Cell and Developmental Biology, the University of Michigan, Ann Arbor, Michigan 48109, the Department of Biology, the University of North Carolina, Chapel Hill, North Carolina 27599, the Curriculum in Genetics and Molecular Biology, the University of North Carolina, Chapel Hill, North Carolina 27599
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7
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Guo Y, Zanetti G, Schekman R. A novel GTP-binding protein-adaptor protein complex responsible for export of Vangl2 from the trans Golgi network. eLife 2013; 2:e00160. [PMID: 23326640 PMCID: PMC3539332 DOI: 10.7554/elife.00160] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Accepted: 10/18/2012] [Indexed: 01/03/2023] Open
Abstract
Planar cell polarity (PCP) requires the asymmetric sorting of distinct signaling
receptors to distal and proximal surfaces of polarized epithelial cells. We have
examined the transport of one PCP signaling protein, Vangl2, from the
trans Golgi network (TGN) in mammalian cells. Using siRNA
knockdown experiments, we find that the GTP-binding protein, Arfrp1, and the clathrin
adaptor complex 1 (AP-1) are required for Vangl2 transport from the TGN. In contrast,
TGN export of Frizzled 6, which localizes to the opposing epithelial surface from
Vangl2, does not depend on Arfrp1 or AP-1. Mutagenesis studies identified a YYXXF
sorting signal in the C-terminal cytosolic domain of Vangl2 that is required for
Vangl2 traffic and interaction with the μ subunit of AP-1. We propose that
Arfrp1 exposes a binding site on AP-1 that recognizes the Vangl2 sorting motif for
capture into a transport vesicle destined for the proximal surface of a polarized
epithelial cell. DOI:http://dx.doi.org/10.7554/eLife.00160.001 Most cells in multicellular organisms possess a property known as polarity that is
reflected, in part, in the organization of the cell surface into distinct domains.
One well-known axis in epithelial cells, such as those in the skin, divides the cell
into an apical domain, which faces out, and a basal domain, which faces the
underlying tissue. These cells rely on the distribution of structural components
inside the cell, or within the cell membrane, to tell the difference between these
two directions. Epithelial cells also possess a second type of polarity, planar cell
polarity, that ensures that cells adjacent to each other in the plane parallel to the
skin tissue are oriented correctly with respect to each other during development.
This ensures, in turn, that hairs, scales, feathers and so on are all aligned. All eukaryotic cells sort and process proteins within an organelle called the Golgi
apparatus, and proteins that are required at a specific destination within the cell,
such as the cell surface membrane, carry specific molecular sorting signals that act
as address labels to convey the protein into and within the secretory pathway. As one
of these proteins moves through the Golgi apparatus, its sorting signals are
recognized by coat proteins, such as clathrin, that subsequently form a vesicle
around it. The assembly of this vesicle is initiated by an enzyme from the Arf
family, but the enzyme must first undergo a conformational change (by exchanging a
molecule of GDP for one of GTP) before formation can begin. The resulting vesicle can
then be sent on its way to the address indicated by its Golgi-to-cell-surface sorting
signal. These sorting signals also help to establish planar cell polarity in cells by
ensuring that proteins called signaling receptors are distributed asymmetrically
within the cell membrane. Guo et al. have now examined the mechanism behind the asymmetric sorting of two
proteins that are involved in planar cell polarity: Vangl2 and Frizzled 6. In an
effort to understand why these proteins are localized to opposite surfaces of
epithelial cells, Guo et al. used genetic techniques to reduce the expression of
Golgi-localized Arf proteins in epithelial cell cultures. They found that knockdown
of a protein called Arfrp1 caused Vangl2 to accumulate in the last station of the
Golgi complex instead of being transported to the cell surface membrane. Then, using
a technique called affinity chromatography, they demonstrated that a coat protein
called the clathrin adaptor complex (AP-1) had to be present for the formation of
vesicles around Vangl2. Moreover, disrupting AP-1 and Arfrp1 did not prevent Frizzled
6 being transported to the cell surface membrane. This suggests that cells use
several distinct adaptor proteins and coat complexes to ensure that proteins from the
Golgi apparatus go to specific locations on the cell surface and, thus, help to
establish planar cell polarity. DOI:http://dx.doi.org/10.7554/eLife.00160.002
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Affiliation(s)
- Yusong Guo
- Department of Molecular and Cell Biology , Howard Hughes Medical Institute, University of California-Berkeley , Berkeley , United States
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8
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Shiba Y, Randazzo PA. ArfGAP1 function in COPI mediated membrane traffic: currently debated models and comparison to other coat-binding ArfGAPs. Histol Histopathol 2012; 27:1143-53. [PMID: 22806901 DOI: 10.14670/hh-27.1143] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The ArfGAPs are a family of proteins containing an ArfGAP catalytic domain that induces the hydrolysis of GTP bound to the small guanine nucleotide binding-protein ADP-ribosylation factor (Arf). Functional models for Arfs, which are regulators of membrane traffic, are based on the idea that guanine nucleotide-binding proteins function as switches: Arf with GTP bound is active and binds to effector proteins; the conversion of GTP to GDP inactivates Arf. The cellular activities of ArfGAPs have been examined primarily as regulatory proteins that inactivate Arf; however, Arf function in membrane traffic does not strictly adhere to the concept of a simple switch, adding complexity to models explaining the role of ArfGAPs. Here, we review the literature addressing the function Arf and ArfGAP1 in COPI mediated transport, focusing on two critical and integrated functions of membrane traffic, cargo sorting and vesicle coat polymerization. We briefly discuss other ArfGAPs that may have similar function in Arf-dependent membrane traffic outside the ER-Golgi.
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Affiliation(s)
- Yoko Shiba
- National Cancer Institute, Laboratory of Cellular and Molecular Biology, Bethesda, MD 20892, USA
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9
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Brown FC, Schindelhaim CH, Pfeffer SR. GCC185 plays independent roles in Golgi structure maintenance and AP-1-mediated vesicle tethering. ACTA ACUST UNITED AC 2011; 194:779-87. [PMID: 21875948 PMCID: PMC3171126 DOI: 10.1083/jcb.201104019] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
GCC185 is a long coiled-coil protein localized to the trans-Golgi network (TGN) that functions in maintaining Golgi structure and tethering mannose 6-phosphate receptor (MPR)-containing transport vesicles en route to the Golgi. We report the identification of two distinct domains of GCC185 needed either for Golgi structure maintenance or transport vesicle tethering, demonstrating the independence of these two functions. The domain needed for vesicle tethering binds to the clathrin adaptor AP-1, and cells depleted of GCC185 accumulate MPRs in transport vesicles that are AP-1 decorated. This study supports a previously proposed role of AP-1 in retrograde transport of MPRs from late endosomes to the Golgi and indicates that docking may involve the interaction of vesicle-associated AP-1 protein with the TGN-associated tethering protein GCC185.
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Affiliation(s)
- Frank C Brown
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
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10
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Abstract
The majority of cells of the immune system are specialized secretory cells, whose function depends on regulated exocytosis. The latter is mediated by vesicular transport involving the sorting of specialized cargo into the secretory granules (SGs), thereby generating the transport vesicles; their transport along the microtubules and eventually their signal-dependent fusion with the plasma membrane. Each of these steps is tightly controlled by mechanisms, which involve the participation of specific sorting signals on the cargo proteins and their recognition by cognate adaptor proteins, posttranslational modifications of the cargo proteins and multiple GTPases and SNARE proteins. In some of the cells (i.e. mast cells, T killer cells) an intimate connection exists between the secretory system and the endocytic one, whereby the SGs are lysosome related organelles (LROs) also referred to as secretory lysosomes. Herein, we discuss these mechanisms in health and disease states.
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Affiliation(s)
- Anat Benado
- Department of Cell and Developmental Biology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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11
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Angers CG, Merz AJ. New links between vesicle coats and Rab-mediated vesicle targeting. Semin Cell Dev Biol 2010; 22:18-26. [PMID: 20643221 DOI: 10.1016/j.semcdb.2010.07.003] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Revised: 07/07/2010] [Accepted: 07/09/2010] [Indexed: 12/24/2022]
Abstract
Vesicle trafficking is a highly regulated process that transports proteins and other cargoes through eukaryotic cells while maintaining cellular organization and compartmental identity. In order for cargo to reach the correct destination, each step of trafficking must impart specificity. During vesicle formation, this is achieved by coat proteins, which selectively incorporate cargo into the nascent vesicle. Classically, vesicle coats are thought to dissociate shortly after budding. However, recent studies suggest that coat proteins can remain on the vesicle en route to their destination, imparting targeting specificity by physically and functionally interacting with Rab-regulated tethering systems. This review focuses on how interactions among Rab GTPases, tethering factors, SNARE proteins, and vesicle coats contribute to vesicle targeting, fusion, and coat dynamics.
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Affiliation(s)
- Cortney G Angers
- Department of Biochemistry, University of Washington School of Medicine, Seattle, WA 98195-3750, USA
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12
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Dumaresq-Doiron K, Savard MF, Akam S, Costantino S, Lefrancois S. The phosphatidylinositol 4-kinase PI4KIIIalpha is required for the recruitment of GBF1 to Golgi membranes. J Cell Sci 2010; 123:2273-80. [PMID: 20530568 DOI: 10.1242/jcs.055798] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sorting from the Golgi apparatus requires the recruitment of cytosolic coat proteins to package cargo into trafficking vesicles. An important early step in the formation of trafficking vesicles is the activation of Arf1 by the guanine nucleotide exchange factor GBF1. To activate Arf1, GBF1 must be recruited to and bound to Golgi membranes, a process that requires Rab1b. However, the mechanistic details of how Rab1 is implicated in GBF1 recruitment are not known. In this study, we demonstrate that the recruitment of GBF1 also requires phosphatidylinositol 4-phosphate [PtdIns(4)P]. Inhibitors of PtdIns(4)P synthesis or depletion of PI4KIIIalpha, a phosphatidylinositol 4-kinase localized to the endoplasmic reticulum and Golgi, prevents the recruitment of GBF1 to Golgi membranes. Interestingly, transfection of dominant-active Rab1 increased the amount of PtdIns(4)P at the Golgi, as detected by GFP-PH, a PtdIns(4)P-sensing probe. We propose that Rab1 contributes to the specificity and timing of GBF1 recruitment by activating PI4KIIIalpha. The PtdIns(4)P produced then allows GBF1 to bind to Golgi membranes and activate Arf1.
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Affiliation(s)
- Karine Dumaresq-Doiron
- Centre de Recherche de l'Hôpital Maisonneuve-Rosemont et Département de Médecine, Université de Montréal, Montréal, Québec H1T 2M4, Canada
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Spang A, Shiba Y, Randazzo PA. Arf GAPs: gatekeepers of vesicle generation. FEBS Lett 2010; 584:2646-51. [PMID: 20394747 DOI: 10.1016/j.febslet.2010.04.005] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2010] [Revised: 03/26/2010] [Accepted: 04/03/2010] [Indexed: 11/17/2022]
Abstract
Arf GAP proteins are a versatile and diverse group of proteins. They control the activity of the GTP-binding proteins of the ARF family by inducing the hydrolysis of GTP that is bound to Arf proteins. The best-studied role of Arf GAPs is in intracellular traffic. In this review, we will focus mainly on the Arf GAPs that play a role in vesicle formation, Arf GAP1, Arf GAP2 and Arf GAP3 and their yeast homologues, Gcs1p and Glo3p. We discuss the roles of Arf GAPs as regulators and effectors for Arf GTP-binding proteins.
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Affiliation(s)
- Anne Spang
- University of Basel, Growth and Development, Biozentrum, Switzerland.
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Pusapati GV, Krndija D, Armacki M, von Wichert G, von Blume J, Malhotra V, Adler G, Seufferlein T. Role of the second cysteine-rich domain and Pro275 in protein kinase D2 interaction with ADP-ribosylation factor 1, trans-Golgi network recruitment, and protein transport. Mol Biol Cell 2010; 21:1011-22. [PMID: 20089835 PMCID: PMC2836954 DOI: 10.1091/mbc.e09-09-0814] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Protein kinase D (PKD) isoenzymes regulate the formation of transport carriers from the trans-Golgi network (TGN) that are en route to the plasma membrane. The PKD C1a domain is required for the localization of PKDs at the TGN. However, the precise mechanism of how PKDs are recruited to the TGN is still elusive. Here, we report that ADP-ribosylation factor (ARF1), a small GTPase of the Ras superfamily and a key regulator of secretory traffic, specifically interacts with PKD isoenzymes. ARF1, but not ARF6, binds directly to the second cysteine-rich domain (C1b) of PKD2, and precisely to Pro275 within this domain. Pro275 in PKD2 is not only crucial for the PKD2-ARF1 interaction but also for PKD2 recruitment to and PKD2 function at the TGN, namely, protein transport to the plasma membrane. Our data suggest a novel model in which ARF1 recruits PKD2 to the TGN by binding to Pro275 in its C1b domain followed by anchoring of PKD2 in the TGN membranes via binding of its C1a domain to diacylglycerol. Both processes are critical for PKD2-mediated protein transport.
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15
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Dehring DAK, Adler AS, Hosseini A, Hicke L. A C-terminal sequence in the guanine nucleotide exchange factor Sec7 mediates Golgi association and interaction with the Rsp5 ubiquitin ligase. J Biol Chem 2008; 283:34188-96. [PMID: 18832381 PMCID: PMC2590713 DOI: 10.1074/jbc.m806023200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2008] [Revised: 09/22/2008] [Indexed: 12/17/2022] Open
Abstract
Arf GTPases control vesicle formation from different intracellular membranes and are regulated by Arf guanine nucleotide exchange factors (GEFs). Outside of their conserved catalytic domains, known as Sec7 domains, little is known about Arf GEFs. Rsp5 is a yeast ubiquitin ligase that regulates numerous membrane trafficking events and carries a C2 domain that is specifically required for trans-Golgi network to vacuole transport. In a screen for proteins that interact with the Rsp5 C2 domain we identified Sec7, the GEF that acts on Golgi-associated Arfs. The Rsp5-Sec7 interaction is direct, occurs in vivo, and is conserved among mammalian Rsp5 and Sec7 homologues. A 50-amino acid region near the Sec7 C terminus is required for Rsp5 binding and for normal Sec7 localization. Binding of Sec7 to Rsp5 is dependent on the presence of the phosphoinositide 3-kinase Vps34, suggesting that phosphatidylinositol 3-phosphate (PI(3)P) plays a role in regulating this interaction. Overexpression of Sec7 significantly suppresses the growth and sorting defects of an rsp5 C2 domain point mutant. These observations identify a new functional region within the Sec7/BIG family of Arf GEFs that is required for trans-Golgi network localization.
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Affiliation(s)
- Deborah A Klos Dehring
- Department of Biochemistry, Molecular Biology & Cell Biology, Northwestern University, Evanston, Illinois 60208, USA
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Disruption of AP1S1, causing a novel neurocutaneous syndrome, perturbs development of the skin and spinal cord. PLoS Genet 2008; 4:e1000296. [PMID: 19057675 PMCID: PMC2585812 DOI: 10.1371/journal.pgen.1000296] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2007] [Accepted: 11/04/2008] [Indexed: 12/19/2022] Open
Abstract
Adaptor protein (AP) complexes regulate clathrin-coated vesicle assembly, protein cargo sorting, and vesicular trafficking between organelles in eukaryotic cells. Because disruption of the various subunits of the AP complexes is embryonic lethal in the majority of cases, characterization of their function in vivo is still lacking. Here, we describe the first mutation in the human AP1S1 gene, encoding the small subunit σ1A of the AP-1 complex. This founder splice mutation, which leads to a premature stop codon, was found in four families with a unique syndrome characterized by mental retardation, enteropathy, deafness, peripheral neuropathy, ichthyosis, and keratodermia (MEDNIK). To validate the pathogenic effect of the mutation, we knocked down Ap1s1 expression in zebrafish using selective antisens morpholino oligonucleotides (AMO). The knockdown phenotype consisted of perturbation in skin formation, reduced pigmentation, and severe motility deficits due to impaired neural network development. Both neural and skin defects were rescued by co-injection of AMO with wild-type (WT) human AP1S1 mRNA, but not by co-injecting the truncated form of AP1S1, consistent with a loss-of-function effect of this mutation. Together, these results confirm AP1S1 as the gene responsible for MEDNIK syndrome and demonstrate a critical role of AP1S1 in development of the skin and spinal cord. We describe a novel genetic syndrome that we named MEDNIK, to designate a disease characterized by mental retardation, enteropathy, deafness, peripheral neuropathy, ichthyosis and keratodermia. This syndrome was found in four French-Canadian families with a common ancestor and is caused by a mutation in the AP1S1 gene. This gene encodes a subunit (σ1A) of an adaptor protein complex (AP-1) involved in the organisation and transport of many other proteins within the cell. By using rapidly developing zebrafish embryos as a model, we observed that the loss of this gene resulted in broad defects, including skin malformation and severe motor deficits due to impairment of spinal cord development. By expressing the human AP1S1 gene instead of the zebrafish ap1s1 gene, we found that the normal human AP1S1 gene could rescue these developmental deficits but not the human AP1S1 gene bearing the disease-related mutation. Together, our results confirm AP1S1 as the gene responsible for MEDNIK syndrome and demonstrate a critical role of AP1S1 in the development of the skin and the spinal cord.
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Lee I, Drake MT, Traub LM, Kornfeld S. Cargo-sorting signals promote polymerization of adaptor protein-1 in an Arf-1.GTP-independent manner. Arch Biochem Biophys 2008; 479:63-8. [PMID: 18762162 DOI: 10.1016/j.abb.2008.08.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2008] [Revised: 08/06/2008] [Accepted: 08/10/2008] [Indexed: 10/21/2022]
Abstract
Adaptor protein-1 (AP-1) is recruited onto the trans-Golgi network via binding to Arf-1.GTP, cargo-sorting signals and phosphoinositides, where it orchestrates the assembly of clathrin-coated vesicular carriers that transport cargo molecules to endosomes. Here we show that cytosolic AP-1 polymerizes when recruited onto enriched Golgi membranes and liposomes containing covalently attached cargo-sorting signal peptides. Incubation of cytosolic or purified AP-1 with soluble sorting signal peptides also resulted in AP-1 polymerization, showing that Arf-1.GTP and membranes are not required for this process. We propose that cargo-induced polymerization of AP-1 contributes to stabilization of the coat complex in the formation of clathrin-coated buds.
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Affiliation(s)
- Intaek Lee
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
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18
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McCormick PJ, Dumaresq-Doiron K, Pluviose AS, Pichette V, Tosato G, Lefrancois S. Palmitoylation controls recycling in lysosomal sorting and trafficking. Traffic 2008; 9:1984-97. [PMID: 18817523 DOI: 10.1111/j.1600-0854.2008.00814.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
For the efficient trafficking of lysosomal proteins, the cationic-dependent and -independent mannose 6-phosphate receptors and sortilin must bind cargo in the Golgi apparatus, be packaged into clathrin-coated trafficking vesicles and traffic to the endosomes. Once in the endosomes, the receptors release their cargo into the endosomal lumen and recycle back to the Golgi for another round of trafficking, a process that requires retromer. In this study, we demonstrate that palmitoylation is required for the efficient retrograde trafficking of sortilin, and the cationic-independent mannose 6-phosphate as palmitoylation-deficient receptors remain trapped in the endosomes. Importantly, we also show that palmitoylation is required for receptor interaction with retromer as nonpalmitoylated receptor did not interact with retromer. In addition, we have identified DHHC-15 as the palmitoyltransferase responsible for this modification. In summary, we have shown the functional significance of palmitoylation in lysosomal receptor sorting and trafficking.
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Affiliation(s)
- Peter J McCormick
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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19
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Membrane curvature induced by Arf1-GTP is essential for vesicle formation. Proc Natl Acad Sci U S A 2008; 105:11731-6. [PMID: 18689681 DOI: 10.1073/pnas.0805182105] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The GTPase Arf1 is considered as a molecular switch that regulates binding and release of coat proteins that polymerize on membranes to form transport vesicles. Here, we show that Arf1-GTP induces positive membrane curvature and find that the small GTPase can dimerize dependent on GTP. Investigating a possible link between Arf dimerization and curvature formation, we isolated an Arf1 mutant that cannot dimerize. Although it was capable of exerting the classical role of Arf1 as a coat receptor, it could not mediate the formation of COPI vesicles from Golgi-membranes and was lethal when expressed in yeast. Strikingly, this mutant was not able to deform membranes, suggesting that GTP-induced dimerization of Arf1 is a critical step inducing membrane curvature during the formation of coated vesicles.
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20
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Borck G, Mollà-Herman A, Boddaert N, Encha-Razavi F, Philippe A, Robel L, Desguerre I, Brunelle F, Benmerah A, Munnich A, Colleaux L. Clinical, cellular, and neuropathological consequences ofAP1S2mutations: further delineation of a recognizable X-linked mental retardation syndrome. Hum Mutat 2008; 29:966-74. [DOI: 10.1002/humu.20531] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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21
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Ishizaki R, Shin HW, Mitsuhashi H, Nakayama K. Redundant roles of BIG2 and BIG1, guanine-nucleotide exchange factors for ADP-ribosylation factors in membrane traffic between the trans-Golgi network and endosomes. Mol Biol Cell 2008; 19:2650-60. [PMID: 18417613 DOI: 10.1091/mbc.e07-10-1067] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
BIG2 and BIG1 are closely related guanine-nucleotide exchange factors (GEFs) for ADP-ribosylation factors (ARFs) and are involved in the regulation of membrane traffic through activating ARFs and recruiting coat protein complexes, such as the COPI complex and the AP-1 clathrin adaptor complex. Although both ARF-GEFs are associated mainly with the trans-Golgi network (TGN) and BIG2 is also associated with recycling endosomes, it is unclear whether BIG2 and BIG1 share some roles in membrane traffic. We here show that knockdown of both BIG2 and BIG1 by RNAi causes mislocalization of a subset of proteins associated with the TGN and recycling endosomes and blocks retrograde transport of furin from late endosomes to the TGN. Similar mislocalization and protein transport block, including furin, were observed in cells depleted of AP-1. Taken together with previous reports, these observations indicate that BIG2 and BIG1 play redundant roles in trafficking between the TGN and endosomes that involves the AP-1 complex.
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Affiliation(s)
- Ray Ishizaki
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
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22
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Lee I, Doray B, Govero J, Kornfeld S. Binding of cargo sorting signals to AP-1 enhances its association with ADP ribosylation factor 1-GTP. ACTA ACUST UNITED AC 2008; 180:467-72. [PMID: 18250197 PMCID: PMC2234244 DOI: 10.1083/jcb.200709037] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The adaptor protein AP-1 is the major coat protein involved in the formation of clathrin-coated vesicles at the trans-Golgi network. The prevailing view is that AP-1 recruitment involves coincident binding to multiple low-affinity sites comprising adenosine diphosphate ribosylation factor 1 (Arf-1)–guanosine triphosphate (GTP), cargo sorting signals, and phosphoinositides. We now show that binding of cargo signal peptides to AP-1 induces a conformational change in its core domain that greatly enhances its interaction with Arf-1–GTP. In addition, we provide evidence for cross talk between the dileucine and tyrosine binding sites within the AP-1 core domain such that binding of a cargo signal to one site facilitates binding to the other site. The stable association of AP-1 with Arf-1–GTP, which is induced by cargo signals, would serve to provide sufficient time for adaptor polymerization and clathrin recruitment while ensuring the packaging of cargo molecules into the forming transport vesicles.
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Affiliation(s)
- Intaek Lee
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
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23
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Styers ML, Kowalczyk AP, Faundez V. Architecture of the vimentin cytoskeleton is modified by perturbation of the GTPase ARF1. J Cell Sci 2006; 119:3643-54. [PMID: 16912072 DOI: 10.1242/jcs.03147] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Intermediate filaments are required for proper membrane protein trafficking. However, it remains unclear whether perturbations in vesicular membrane transport result in changes in the architecture of the vimentin cytoskeleton. We find that treatment of cells with Brefeldin A, an inhibitor of specific stages of membrane transport, causes changes in the organization of vimentin filaments. These changes arise from movement of pre-existing filaments. Brefeldin A treatment also leads to alterations in the microtubule cytoskeleton. However, this effect is not observed in cells lacking intermediate filaments, indicating that microtubule bundling is downstream of perturbations in the vimentin cytoskeleton. Brefeldin A-induced changes in vimentin architecture are probably mediated through its effects on ADP-ribosylation factor 1 (ARF1). Expression of a dominant-negative mutant of ARF1 induces BFA-like modifications in vimentin morphology. The BFA-dependent changes in vimentin architecture occurred concurrently with the release of the ARF1-regulated adaptor complexes AP-3 and AP-1 from membranes and adaptor redistribution to vimentin networks. These observations indicate that perturbation of the vesicular membrane transport machinery lead to reciprocal changes in the architecture of vimentin networks.
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Affiliation(s)
- Melanie L Styers
- Graduate Program in Biochemistry, Cell, and Developmental Biology, Emory University, Atlanta, GA 30322, USA
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24
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Abstract
The selective transfer of material between membrane-delimited organelles is mediated by protein-coated vesicles. In many instances, formation of membrane trafficking intermediates is regulated by the GTP-binding protein Arf. Binding and hydrolysis of GTP by Arf was originally linked to the assembly and disassembly of vesicle coats. Arf GTPase-activating proteins (GAPs), a family of proteins that induce hydrolysis of GTP bound to Arf, were therefore proposed to regulate the disassembly and dissociation of vesicle coats. Following the molecular identification of Arf GAPs, the roles for GAPs and GTP hydrolysis have been directly examined. GAPs have been found to bind cargo and known coat proteins as well as directly contribute to vesicle formation, which is consistent with the idea that GAPs function as subunits of coat proteins rather than simply Arf inactivators. In addition, GTP hydrolysis induced by GAPs occurs largely before vesicle formation and is required for sorting. These results are the primary basis for modifications to the classical model for the function of Arf in transport vesicle formation, including a recent proposal that Arf has a proofreading, rather than a structural, role.
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Affiliation(s)
- Zhongzhen Nie
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892, USA
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25
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Abstract
The ADP-ribosylation factor (ARF) small GTPases regulate vesicular traffic and organelle structure by recruiting coat proteins, regulating phospholipid metabolism and modulating the structure of actin at membrane surfaces. Recent advances in our understanding of the signalling pathways that are regulated by ARF1 and ARF6, two of the best characterized ARF proteins, provide a molecular context for ARF protein function in fundamental biological processes, such as secretion, endocytosis, phagocytosis, cytokinesis, cell adhesion and tumour-cell invasion.
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Affiliation(s)
- Crislyn D'Souza-Schorey
- Department of Biological Sciences and the Walther Cancer Institute, University of Notre Dame, Notre Dame, Indiana, USA.
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26
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Baust T, Czupalla C, Krause E, Bourel-Bonnet L, Hoflack B. Proteomic analysis of adaptor protein 1A coats selectively assembled on liposomes. Proc Natl Acad Sci U S A 2006; 103:3159-64. [PMID: 16492770 PMCID: PMC1413908 DOI: 10.1073/pnas.0511062103] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Coat components localize to specific membrane domains, where they sort selected transmembrane proteins. To study how clathrin coats are stabilized on such domains and to identify the protein networks involved, we combined proteomic screens and in vitro liposome-based assays that recapitulate the fidelity of protein sorting in vivo. Our study identifying approximately 40 proteins on AP-1A-coated liposomes revealed that AP-1A coat assembly triggers the concomitant recruitment of Rac1, its effectors, and the Wave/Scar complex as well as that of Rab11 and Rab14. The coordinated recruitment of these different machineries requires a mosaic of membrane components comprising the GTPase ADP-ribosylation factor 1, sorting signals in selected transmembrane proteins, and phosphatidylinositol 4-phosphate. These results demonstrate that the combinatorial use of low-affinity binding sites present on the same membrane domain accounts not only for a selective coat assembly but also for the coordinated assembly of selected machineries required for actin polymerization and subsequent membrane fusion.
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Affiliation(s)
- Thorsten Baust
- *Biotechnological Center, Dresden University of Technology, Tatzberg 47-51, 01307 Dresden,Germany
| | - Cornelia Czupalla
- *Biotechnological Center, Dresden University of Technology, Tatzberg 47-51, 01307 Dresden,Germany
| | - Eberhard Krause
- Institute of Molecular Pharmacology, Robert-Rössle-Strasse 10, 13125 Berlin,Germany; and
| | - Line Bourel-Bonnet
- Faculté de Pharmacie de Lille, Laboratoire de Chimie Organique, 3, Rue du Pr. Laguesse, BP 83, 59006 Lille Cedex,France
| | - Bernard Hoflack
- *Biotechnological Center, Dresden University of Technology, Tatzberg 47-51, 01307 Dresden,Germany
- To whom correspondence should be addressed. E-mail:
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27
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Miyazaki H, Yamazaki M, Watanabe H, Maehama T, Yokozeki T, Kanaho Y. The small GTPase ADP-ribosylation factor 6 negatively regulates dendritic spine formation. FEBS Lett 2005; 579:6834-8. [PMID: 16325184 DOI: 10.1016/j.febslet.2005.11.022] [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] [Received: 09/13/2005] [Revised: 10/24/2005] [Accepted: 11/10/2005] [Indexed: 11/19/2022]
Abstract
Actin cytoskeletal reorganization and membrane trafficking are important for spine morphogenesis. Here we investigated whether the small GTPase, ADP-ribosylation factor 6 (ARF6), which regulates actin dynamics and peripheral vesicular trafficking, is involved in the regulation of spine formation. The developmental expression pattern of ARF6 in mouse hippocampus was similar to that of the post-synaptic density protein-95, and these molecules colocalized in mouse hippocampal neurons. Overexpression of a constitutively active ARF6 mutant in cultured hippocampal neurons decreased the spine density, whereas a dominant-negative ARF6 mutant increased the density. These results demonstrate a novel function for ARF6 as a key regulator of spine formation.
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Affiliation(s)
- Hideyuki Miyazaki
- Department of Physiological Chemistry, Graduate School of Comprehensive Sciences and Institute of Basic Medical Sciences, University of Tsukuba, 1-1-1 Ten-nohdai, Tsukuba 305-8575, Japan
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28
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Coleman SH, Hitchin D, Noviello CM, Guatelli JC. HIV-1 Nef stabilizes AP-1 on membranes without inducing ARF1-independent de novo attachment. Virology 2005; 345:148-55. [PMID: 16253302 DOI: 10.1016/j.virol.2005.09.045] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2005] [Revised: 07/11/2005] [Accepted: 09/13/2005] [Indexed: 12/16/2022]
Abstract
HIV-1 Nef affects the trafficking of numerous cellular proteins to optimize viral replication and evade host defenses. The adaptor protein (AP) complexes, which form part of the cytoplasmic coat of endosomal vesicles, are key cellular co-factors for Nef. Nef binds these complexes and alters their physiologic cycle of attachment and release from membranes. Specifically, while AP-1 normally becomes cytosolic when attachment events are blocked by inhibition of the GTPase cycle of ADP-ribosylation factor-1 (ARF1), the complex remains membrane-associated in Nef-expressing cells. To investigate the mechanism of this effect, we used a permeabilized cell system to detect the de novo attachment of exogenous AP-1 to endosomal membranes. Nef did not mediate de novo attachment independently of ARF1, despite its ability to maintain the association of AP-1 with endosomal membranes when the activity of ARF1 was blocked. We conclude that Nef stabilizes AP complexes on endosomal membranes after ARF1-dependent attachment. This stabilization may facilitate coat formation and stimulate the trafficking of multiple cellular proteins.
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Affiliation(s)
- Scott H Coleman
- Department of Medicine, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0679, USA
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29
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Meyer DM, Crottet P, Maco B, Degtyar E, Cassel D, Spiess M. Oligomerization and dissociation of AP-1 adaptors are regulated by cargo signals and by ArfGAP1-induced GTP hydrolysis. Mol Biol Cell 2005; 16:4745-54. [PMID: 16093346 PMCID: PMC1237080 DOI: 10.1091/mbc.e05-06-0568] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The mechanism of AP-1/clathrin coat formation was analyzed using purified adaptor proteins and synthetic liposomes presenting tyrosine sorting signals. AP-1 adaptors recruited in the presence of Arf1.GTP and sorting signals were found to oligomerize to high-molecular-weight complexes even in the absence of clathrin. The appendage domains of the AP-1 adaptins were not required for oligomerization. On GTP hydrolysis induced by the GTPase-activating protein ArfGAP1, the complexes were disassembled and AP-1 dissociated from the membrane. AP-1 stimulated ArfGAP1 activity, suggesting a role of AP-1 in the regulation of the Arf1 "GTPase timer." In the presence of cytosol, AP-1 could be recruited to liposomes without sorting signals, consistent with the existence of docking factors in the cytosol. Under these conditions, however, AP-1 remained monomeric, and recruitment in the presence of GTP was short-lived. Sorting signals allowed stable recruitment and oligomerization also in the presence of cytosol. These results suggest a mechanism whereby initial assembly of AP-1 with Arf1.GTP and ArfGAP1 on the membrane stimulates Arf1 GTPase activity, whereas interaction with cargo induces oligomerization and reduces the rate of GTP hydrolysis, thus contributing to efficient cargo sorting.
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Affiliation(s)
- Daniel M Meyer
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland
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30
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Perry RJ, Ridgway ND. Molecular mechanisms and regulation of ceramide transport. Biochim Biophys Acta Mol Cell Biol Lipids 2005; 1734:220-34. [PMID: 15907394 DOI: 10.1016/j.bbalip.2005.04.001] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2005] [Revised: 04/06/2005] [Accepted: 04/07/2005] [Indexed: 10/25/2022]
Abstract
De novo biosynthesis of sphingolipids begins in the endoplasmic reticulum (ER) and continues in the Golgi apparatus and plasma membrane. A crucial step in sphingolipid biosynthesis is the transport of ceramide by vesicular and non-vesicular mechanisms from its site of synthesis in the ER to the Golgi apparatus. The recent discovery of the ceramide transport protein CERT has revealed a novel pathway for the delivery of ceramide to the Golgi apparatus for sphingomyelin (SM) synthesis. In addition to a ceramide-binding START domain, CERT has FFAT (referring to two phenylalanines [FF] in an acidic tract) and pleckstrin homology (PH) domains that recognize the ER integral membrane protein VAMP-associated protein (VAP) and Golgi-associated PtdIns 4-phosphate, respectively. Mechanisms for vectorial transport involving dual-organellar targeting and sites of deposition of ceramide in the Golgi apparatus are proposed. Similar Golgi-ER targeting motifs are also present in the oxysterol-binding protein (OSBP), which regulates ceramide transport and SM synthesis in an oxysterol-dependent manner. Consequently, this emerges as a potential mechanism for integration of sphingolipid and cholesterol metabolism. The identification of organellar targeting motifs in other related lipid-binding/transport proteins indicate that concepts learned from the study of ceramide transport can be applied to other lipid transport processes.
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Affiliation(s)
- Ryan J Perry
- Atlantic Research Centre, Dalhousie University, 5849 University Avenue, Halifax, N.S., Canada B3H 4H7
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31
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Traub LM. Common principles in clathrin-mediated sorting at the Golgi and the plasma membrane. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2005; 1744:415-37. [PMID: 15922462 DOI: 10.1016/j.bbamcr.2005.04.005] [Citation(s) in RCA: 166] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2005] [Revised: 04/17/2005] [Accepted: 04/19/2005] [Indexed: 12/12/2022]
Abstract
Clathrin-mediated vesicular trafficking events underpin the vectorial transfer of macromolecules between several eukaryotic membrane-bound compartments. Classical models for coat operation, focused principally on interactions between clathrin, the heterotetrameric adaptor complexes, and cargo molecules, fail to account for the full complexity of the coat assembly and sorting process. New data reveal that targeting of clathrin adaptor complexes is generally supported by phosphoinositides, that cargo recognition by heterotetrameric adaptors depends on phosphorylation-driven conformational alterations, and that dedicated clathrin-associated sorting proteins (CLASPs) exist to promote the selective trafficking of specific categories of cargo. A host of accessory factors also participate in coat polymerization events, and the independently folded appendage domains that project off the heterotetrameric adaptor core function as recruitment platforms that appear to oversee assembly operations. It is also now clear that focal polymerization of branched actin microfilaments contributes to clathrin-coated vesicle assembly and movement at both plasma membrane and Golgi sites. This improved appreciation of the complex mechanisms governing clathrin-dependent sorting events reveals several common principles of clathrin operation at the Golgi and the plasma membrane.
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Affiliation(s)
- Linton M Traub
- Department of Cell Biology and Physiology University of Pittsburgh School of Medicine 3500 Terrace Street, S325BST Pittsburgh, PA 15206, USA.
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32
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Bigay J, Casella JF, Drin G, Mesmin B, Antonny B. ArfGAP1 responds to membrane curvature through the folding of a lipid packing sensor motif. EMBO J 2005; 24:2244-53. [PMID: 15944734 PMCID: PMC1173154 DOI: 10.1038/sj.emboj.7600714] [Citation(s) in RCA: 287] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2005] [Accepted: 05/23/2005] [Indexed: 11/08/2022] Open
Abstract
ArfGAP1 promotes GTP hydrolysis in Arf1, a small G protein that interacts with lipid membranes and drives the assembly of the COPI coat in a GTP-dependent manner. The activity of ArfGAP1 increases with membrane curvature, suggesting a negative feedback loop in which COPI-induced membrane deformation determines the timing and location of GTP hydrolysis within a coated bud. Here we show that a central sequence of about 40 amino acids in ArfGAP1 acts as a lipid-packing sensor. This ALPS motif (ArfGAP1 Lipid Packing Sensor) is also found in the yeast homologue Gcs1p and is necessary for coupling ArfGAP1 activity with membrane curvature. The ALPS motif binds avidly to small liposomes and shows the same hypersensitivity on liposome radius as full-length ArfGAP1. Site-directed mutagenesis, limited proteolysis and circular dichroism experiments suggest that the ALPS motif, which is unstructured in solution, inserts bulky hydrophobic residues between loosely packed lipids and forms an amphipathic helix on highly curved membranes. This helix differs from classical amphipathic helices by the abundance of serine and threonine residues on its polar face.
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Affiliation(s)
- Joëlle Bigay
- CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, Sophia Antipolis, France
| | | | - Guillaume Drin
- CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, Sophia Antipolis, France
| | - Bruno Mesmin
- CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, Sophia Antipolis, France
| | - Bruno Antonny
- CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, Sophia Antipolis, France
- CNRS, Institut de Pharmacologie, Moléculaire et Cellulaire, 660 route des lucioles, 06560 Valbonne-Sophia Antipolis, France. Tel.: +33 4 93 95 77 75; Fax: +33 4 93 95 77 10; E-mail:
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33
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Abstract
Plant membrane trafficking shares many features with other eukaryotic organisms, including the machinery for vesicle formation and fusion. However, the plant endomembrane system lacks an ER-Golgi intermediate compartment, has numerous Golgi stacks and several types of vacuoles, and forms a transient compartment during cell division. ER-Golgi trafficking involves bulk flow and efficient recycling of H/KDEL-bearing proteins. Sorting in the Golgi stacks separates bulk flow to the plasma membrane from receptor-mediated trafficking to the lytic vacuole. Cargo for the protein storage vacuole is delivered from the endoplasmic reticulum (ER), cis-Golgi, and trans-Golgi. Endocytosis includes recycling of plasma membrane proteins from early endosomes. Late endosomes appear identical with the multivesiculate prevacuolar compartment that lies on the Golgi-vacuole trafficking pathway. In dividing cells, homotypic fusion of Golgi-derived vesicles forms the cell plate, which expands laterally by targeted vesicle fusion at its margin, eventually fusing with the plasma membrane.
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Affiliation(s)
- Gerd Jurgens
- ZMBP, Entwicklungsgenetik, Universitat Tubingen, 72076 Tubingen, Germany.
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34
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Heldwein EE, Macia E, Wang J, Yin HL, Kirchhausen T, Harrison SC. Crystal structure of the clathrin adaptor protein 1 core. Proc Natl Acad Sci U S A 2004; 101:14108-13. [PMID: 15377783 PMCID: PMC521094 DOI: 10.1073/pnas.0406102101] [Citation(s) in RCA: 155] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The heterotetrameric adaptor proteins (AP complexes) link the outer lattice of clathrin-coated vesicles with membrane-anchored cargo molecules. We report the crystal structure of the core of the AP-1 complex, which functions in the trans-Golgi network (TGN). Packing of complexes in the crystal generates an exceptionally long (1,135-A) unit-cell axis, but the 6-fold noncrystallographic redundancy yields an excellent map at 4-A resolution. The AP-1 core comprises N-terminal fragments of the two large chains, beta1 and gamma, and the intact medium and small chains, micro1 and sigma1. Its molecular architecture closely resembles that of the core of AP-2, the plasma-membrane-specific adaptor, for which a structure has been determined. Both structures represent an "inactive" conformation with respect to binding of cargo with a tyrosine-based sorting signal. TGN localization of AP-1 depends on the small GTPase, Arf1, and the phosphoinositide, PI-4-P. We show that directed mutations of residues at a particular corner of the gamma chain prevent recruitment to the TGN in cells and diminish PI-4-P-dependent, but not Arf1-dependent, liposome binding in vitro.
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Affiliation(s)
- Ekaterina E Heldwein
- Children's Hospital, Howard Hughes Medical Institute, Department of Cell Biology, and CBR Institute for Biomedical Research, Harvard Medical School, Boston, MA 02115, USA
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35
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Horng JT, Tan CY. Biochemical characterization of the coating mechanism of the endosomal donor compartment of synaptic vesicles. Neurochem Res 2004; 29:1411-6. [PMID: 15202773 DOI: 10.1023/b:nere.0000026405.62006.88] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The heterotetrameric adaptor protein complex, AP-3, sorts proteins to both the endosome/lysosome and the synaptic vesicles. We have characterized the recruitment of pure AP-3 complex and ADP-ribosylation factor (ARF) onto the endosomal donor compartments that give rise to synaptic vesicles. We demonstrated that endosomes become heavier in a sucrose gradient after incubation with rat brain cytosol and a nonhydrolyzable GTP analog, GTPgammaS. This process requires a small GTPase, ARF-1. Furthermore, the endosomal coating is specific for AP-3 but not the AP-2 complex. This process requires only two soluble proteins AP-3 and ARF, with the recruitment of AP-3 being saturable at about 30 nM. These results establish that the synaptic vesicle's donor membrane is coated with AP-3 before vesiculation, in a coat-protein-specific and dose-dependent fashion.
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Affiliation(s)
- Jim-Tong Horng
- Department of Biochemistry, Chang Gung University, Kweishan, Taiwan.
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36
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Randazzo PA, Hirsch DS. Arf GAPs: multifunctional proteins that regulate membrane traffic and actin remodelling. Cell Signal 2004; 16:401-13. [PMID: 14709330 DOI: 10.1016/j.cellsig.2003.09.012] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The ADP-ribosylation factor (Arf) Arf GTPase-activating proteins (GAPs) are a family of proteins that induce hydrolysis of GTP bound to Arf. A conserved domain containing a zinc finger motif mediates catalysis. The substrate, Arf.GTP, affects membrane trafficking and actin remodelling. Consistent with activity as an Arf regulator, the Arf GAPs affect both of these pathways. However, the Arf GAPs are likely to have Arf-independent activities that contribute to their cellular functions. Structures of the Arf GAPs are diverse containing catalytic, protein-protein interaction and lipid interaction domains in addition to the Arf GAP domain. Some Arf GAPs have been identified and characterized on the basis of activities other than Arf GAP. Here, we describe the Arf GAP family, enzymology of some members of the Arf GAP family and known functions of the proteins. The results discussed illustrate roles for both Arf-dependent and -independent activities in the regulation of cellular architecture.
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Affiliation(s)
- Paul A Randazzo
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, Building. 37 Room 4118, Bethesda, MD 20892, USA.
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37
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Bigay J, Gounon P, Robineau S, Antonny B. Lipid packing sensed by ArfGAP1 couples COPI coat disassembly to membrane bilayer curvature. Nature 2003; 426:563-6. [PMID: 14654841 DOI: 10.1038/nature02108] [Citation(s) in RCA: 246] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2003] [Accepted: 10/07/2003] [Indexed: 11/09/2022]
Abstract
Protein coats deform flat lipid membranes into buds and capture membrane proteins to form transport vesicles. The assembly/disassembly cycle of the COPI coat on Golgi membranes is coupled to the GTP/GDP cycle of the small G protein Arf1. At the heart of this coupling is the specific interaction of membrane-bound Arf1-GTP with coatomer, a complex of seven proteins that forms the building unit of the COPI coat. Although COPI coat disassembly requires the catalysis of GTP hydrolysis in Arf1 by a specific GTPase-activating protein (ArfGAP1), the precise timing of this reaction during COPI vesicle formation is not known. Using time-resolved assays for COPI dynamics on liposomes of controlled size, we show that the rate of ArfGAP1-catalysed GTP hydrolysis in Arf1 and the rate of COPI disassembly increase over two orders of magnitude as the curvature of the lipid bilayer increases and approaches that of a typical transport vesicle. This leads to a model for COPI dynamics in which GTP hydrolysis in Arf1 is organized temporally and spatially according to the changes in lipid packing induced by the coat.
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Affiliation(s)
- Joëlle Bigay
- Institut de Pharmacologie Moléculaire et Cellulaire, CNRS, 660 route des Lucioles, 06560 Valbonne-Sophia-Antipolis, France
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38
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Hill K, Li Y, Bennett M, McKay M, Zhu X, Shern J, Torre E, Lah JJ, Levey AI, Kahn RA. Munc18 interacting proteins: ADP-ribosylation factor-dependent coat proteins that regulate the traffic of beta-Alzheimer's precursor protein. J Biol Chem 2003; 278:36032-40. [PMID: 12842896 DOI: 10.1074/jbc.m301632200] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Coat proteins cycle between soluble and membrane-bound locations at the time of vesicle biogenesis and act to regulate the assembly of the vesicle coat that determines the specificity in cargo selection and the destination of the vesicle. A transmembrane cargo protein, an Arf GTPase, and a coat protein (e.g. COPs, APs, or GGAs) are minimal components required for budding of vesicles. Munc18 interacting proteins (MINTs) are a family of three proteins implicated in the localization of receptors to the plasma membrane. We show that MINTs bind Arfs directly, co-localize with Arf and the Alzheimer's precursor protein (beta-APP) to regions of the Golgi/trans-Golgi network, and can co-immunoprecipitate clathrin. We demonstrate that MINTs bind Arfs through a region of the PTB domain and the PDZ2 domain, and Arf-MINT interaction is necessary for the increased cellular levels of beta-APP produced by MINT overexpression. Knockdown (small interference RNA) experiments implicate beta-APP as a transmembrane cargo protein that works together with MINTs. We propose that MINTs are a family of Arf-dependent, vesicle-coat proteins that can regulate the traffic of beta-APP.
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Affiliation(s)
- Karen Hill
- Department of Biochemistry, School of Medicine, Emory University, Atlanta, Georgia 30322-3050, USA
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39
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Wang YJ, Wang J, Sun HQ, Martinez M, Sun YX, Macia E, Kirchhausen T, Albanesi JP, Roth MG, Yin HL. Phosphatidylinositol 4 phosphate regulates targeting of clathrin adaptor AP-1 complexes to the Golgi. Cell 2003; 114:299-310. [PMID: 12914695 DOI: 10.1016/s0092-8674(03)00603-2] [Citation(s) in RCA: 583] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Phosphatidylinositol 4 phosphate [PI(4)P] is essential for secretion in yeast, but its role in mammalian cells is unclear. Current paradigms propose that PI(4)P acts primarily as a precursor to phosphatidylinositol 4,5 bisphosphate (PIP2), an important plasma membrane regulator. We found that PI(4)P is enriched in the mammalian Golgi, and used RNA interference (RNAi) of PI4KIIalpha, a Golgi resident phosphatidylinositol 4 kinase, to determine whether PI(4)P directly regulates the Golgi. PI4KIIalpha RNAi decreases Golgi PI(4)P, blocks the recruitment of clathrin adaptor AP-1 complexes to the Golgi, and inhibits AP-1-dependent functions. This AP-1 binding defect is rescued by adding back PI(4)P. In addition, purified AP-1 binds PI(4)P, and anti-PI(4)P inhibits the in vitro recruitment of cytosolic AP-1 to normal cellular membranes. We propose that PI4KIIalpha establishes the Golgi's unique lipid-defined organelle identity by generating PI(4)P-rich domains that specify the docking of the AP-1 coat machinery.
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Affiliation(s)
- Ying Jie Wang
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
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40
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Abstract
Arf GTP-binding proteins regulate membrane traffic and actin remodeling. Similar to other GTP-binding proteins, a complex of Arf-GTP with an effector protein mediates Arf function. Arf interacts with at least three qualitatively different types of effectors. First, it interacts with structural proteins, the vesicle coat proteins. The second type of effector is lipid-metabolizing enzymes, and the third comprises those proteins that bind to Arf-GTP but whose biochemical or biological functions are not yet clearly defined. Arf interacts with two other families of proteins, the exchange factors and the GTPase-activating proteins. Recent work examining the functional relationships among the diverse Arf interactors has led to reconsideration of the prevailing paradigms for Arf action.
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Affiliation(s)
- Zhongzhen Nie
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, Building 37, Room 4118, Bethesda, MD 20892, USA
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41
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Janvier K, Craig H, Hitchin D, Madrid R, Sol-Foulon N, Renault L, Cherfils J, Cassel D, Benichou S, Guatelli J. HIV-1 Nef stabilizes the association of adaptor protein complexes with membranes. J Biol Chem 2003; 278:8725-32. [PMID: 12486136 DOI: 10.1074/jbc.m210115200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The maximal virulence of HIV-1 requires Nef, a virally encoded peripheral membrane protein. Nef binds to the adaptor protein (AP) complexes of coated vesicles, inducing an expansion of the endosomal compartment and altering the surface expression of cellular proteins including CD4 and class I major histocompatibility complex. Here, we show that Nef stabilizes the association of AP-1 and AP-3 with membranes. These complexes remained with Nef on juxtanuclear membranes despite the treatment of cells with brefeldin A, which induced the release of ADP-ribosylation factor 1 (ARF1) from these membranes to the cytosol. Nef also induced a persistent association of AP-1 and AP-3 with membranes despite the expression of dominant-negative ARF1 or the overexpression of an ARF1-GTPase activating protein. Mutational analysis indicated that the direct binding of Nef to the AP complexes is essential for this stabilization. The leucine residues of the EXXXLL motif found in Nef were required for binding to AP-1 and AP-3 in vitro and for the stabilization of these complexes on membranes in vivo, whereas the glutamic acid residue of this motif was required specifically for the binding and stabilization of AP-3. These data indicate that Nef mediates the persistent attachment of AP-1 and AP-3 to membranes by an ARF1-independent mechanism. The stabilization of these complexes on membranes may underlie the pleiotropic effects of Nef on protein trafficking within the endosomal system.
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Affiliation(s)
- Katy Janvier
- Institut Cochin, Department of Infectious Diseases, INSERM U567-CNRS UMR8104, Universite Paris V, 24 Rue du Faubourg Saint-Jacques, France
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42
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Ghosh P, Kornfeld S. AP-1 binding to sorting signals and release from clathrin-coated vesicles is regulated by phosphorylation. J Cell Biol 2003; 160:699-708. [PMID: 12604586 PMCID: PMC2173368 DOI: 10.1083/jcb.200211080] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The adaptor protein complex-1 (AP-1) sorts and packages membrane proteins into clathrin-coated vesicles (CCVs) at the TGN and endosomes. Here we show that this process is highly regulated by phosphorylation of AP-1 subunits. Cell fractionation studies revealed that membrane-associated AP-1 differs from cytosolic AP-1 in the phosphorylation status of its beta1 and mu1 subunits. AP-1 recruitment onto the membrane is associated with protein phosphatase 2A (PP2A)-mediated dephosphorylation of its beta1 subunit, which enables clathrin assembly. This Golgi-associated isoform of PP2A exhibits specificity for phosphorylated beta1 compared with phosphorylated mu1. Once on the membrane, the mu1 subunit undergoes phosphorylation, which results in a conformation change, as revealed by increased sensitivity to trypsin. This conformational change is associated with increased binding to sorting signals on the cytoplasmic tails of cargo molecules. Dephosphorylation of mu1 (and mu2) by another PP2A-like phosphatase reversed the effect and resulted in adaptor release from CCVs. Immunodepletion and okadaic acid inhibition studies demonstrate that PP2A is the cytosolic cofactor for Hsc-70-mediated adaptor uncoating. A model is proposed where cyclical phosphorylation/dephosphorylation of the subunits of AP-1 regulate its function from membrane recruitment until its release into cytosol.
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Affiliation(s)
- Pradipta Ghosh
- Washington University School of Medicine, Department of Internal Medicine, 660 S. Euclid Ave., Box 8125, St. Louis, MO 63110, USA
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43
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Wu X, Zhao X, Puertollano R, Bonifacino JS, Eisenberg E, Greene LE. Adaptor and clathrin exchange at the plasma membrane and trans-Golgi network. Mol Biol Cell 2003; 14:516-28. [PMID: 12589051 PMCID: PMC149989 DOI: 10.1091/mbc.e02-06-0353] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
We previously demonstrated, using fluorescence recovery after photobleaching, that clathrin in clathrin-coated pits at the plasma membrane exchanges with free clathrin in the cytosol, suggesting that clathrin-coated pits are dynamic structures. We now investigated whether clathrin at the trans-Golgi network as well as the clathrin adaptors AP2 and AP1 in clathrin-coated pits at the plasma membrane and trans-Golgi network, respectively, also exchange with free proteins in the cytosol. We found that when the budding of clathrin-coated vesicle is blocked without significantly affecting the structure of clathrin-coated pits, both clathrin and AP2 at the plasma membrane and clathrin and AP1 at the trans-Golgi network exchange rapidly with free proteins in the cytosol. In contrast, when budding of clathrin-coated vesicles was blocked at the plasma membrane or trans-Golgi network by hypertonic sucrose or K(+) depletion, conditions that markedly affect the structure of clathrin-coated pits, clathrin exchange was blocked but AP2 at the plasma membrane and both AP1 and the GGA1 adaptor at the trans-Golgi network continue to rapidly exchange. We conclude that clathrin-coated pits are dynamic structures with rapid exchange of both clathrin and adaptors and that adaptors are able to exchange independently of clathrin when clathrin exchange is blocked.
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Affiliation(s)
- Xufeng Wu
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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44
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Waguri S, Dewitte F, Le Borgne R, Rouillé Y, Uchiyama Y, Dubremetz JF, Hoflack B. Visualization of TGN to endosome trafficking through fluorescently labeled MPR and AP-1 in living cells. Mol Biol Cell 2003; 14:142-55. [PMID: 12529433 PMCID: PMC140234 DOI: 10.1091/mbc.e02-06-0338] [Citation(s) in RCA: 152] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
We have stably expressed in HeLa cells a chimeric protein made of the green fluorescent protein (GFP) fused to the transmembrane and cytoplasmic domains of the mannose 6-phosphate/insulin like growth factor II receptor in order to study its dynamics in living cells. At steady state, the bulk of this chimeric protein (GFP-CI-MPR) localizes to the trans-Golgi network (TGN), but significant amounts are also detected in peripheral, tubulo-vesicular structures and early endosomes as well as at the plasma membrane. Time-lapse videomicroscopy shows that the GFP-CI-MPR is ubiquitously detected in tubular elements that detach from the TGN and move toward the cell periphery, sometimes breaking into smaller tubular fragments. The formation of the TGN-derived tubules is temperature dependent, requires the presence of intact microtubule and actin networks, and is regulated by the ARF-1 GTPase. The TGN-derived tubules fuse with peripheral, tubulo-vesicular structures also containing the GFP-CI-MPR. These structures are highly dynamic, fusing with each other as well as with early endosomes. Time-lapse videomicroscopy performed on HeLa cells coexpressing the CFP-CI-MPR and the AP-1 complex whose gamma-subunit was fused to YFP shows that AP-1 is present not only on the TGN and peripheral CFP-CI-MPR containing structures but also on TGN-derived tubules containing the CFP-CI-MPR. The data support the notion that tubular elements can mediate MPR transport from the TGN to a peripheral, tubulo-vesicular network dynamically connected with the endocytic pathway and that the AP-1 coat may facilitate MPR sorting in the TGN and endosomes.
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Affiliation(s)
- Satoshi Waguri
- Institut de Biologie, EP CNRS 525, Institut Pasteur de Lille, 59021 Lille Cedex, France
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45
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Hirsch DS, Stanley KT, Chen LX, Jacques KM, Puertollano R, Randazzo PA. Arf regulates interaction of GGA with mannose-6-phosphate receptor. Traffic 2003; 4:26-35. [PMID: 12535273 DOI: 10.1034/j.1600-0854.2003.40105.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The role of ADP-ribosylation factor (Arf) in Golgi associated, gamma-adaptin homologous, Arf-interacting protein (GGA)-mediated membrane traffic was examined. GGA is a clathrin adaptor protein that binds Arf through its GAT domain and the mannose-6-phosphate receptor through its VHS domain. The GAT and VHS domains interacted such that Arf and mannose-6-phosphate receptor binding to GGA were mutually exclusive. In vivo, GGA bound membranes through either Arf or mannose-6-phosphate receptor. However, mannose-6-phosphate receptor excluded Arf from GGA-containing structures outside of the Golgi. These data are inconsistent with predictions based on the model for Arf's role in COPI veside coat function. We propose that Arf recruits GGA to a membrane and then, different from the current model, 'hands-off' GGA to mannose-6-phosphate receptor. GGA and mannose-6-phosphate receptor are then incorporated into a transport intermediate that excludes Arf.
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Affiliation(s)
- Dianne Snow Hirsch
- Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, Bldg 37 Room 6032 and Cell Biology and Metabolism Branch, National Institute of Child Health and Development, National Institutes of Health, Bethesda. MD 20892, USA
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46
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Nakayama K, Wakatsuki S. The Structure and Function of GGAs, the Traffic Controllers at the TGN Sorting Crossroads. Cell Struct Funct 2003; 28:431-42. [PMID: 14745135 DOI: 10.1247/csf.28.431] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
GGAs (Golgi-localizing, gamma-adaptin ear homology domain, ARF-binding proteins) are a family of monomeric clathrin adaptor proteins that are conserved from yeasts to humans. Data published during the past four years have provided detailed pictures of the localization, domain organization and structure-function relationships of GGAs. GGAs possess four conserved functional domains, each of which interacts with cargo proteins including mannose 6-phosphate receptors, the small GTPase ARF, clathrin, or accessory proteins including Rabaptin-5 and gamma-synergin. Together with or independent of the adaptor protein complex AP-1, GGAs regulate selective transport of cargo proteins, such as mannose 6-phosphate receptors, from the trans-Golgi network to endosomes mediated by clathrin-coated vesicles.
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Affiliation(s)
- Kazuhisa Nakayama
- Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida-shimoadachi, Sakyo-ku, Kyoto 606-8501, Japan.
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47
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Jacques KM, Nie Z, Stauffer S, Hirsch DS, Chen LX, Stanley KT, Randazzo PA. Arf1 dissociates from the clathrin adaptor GGA prior to being inactivated by Arf GTPase-activating proteins. J Biol Chem 2002; 277:47235-41. [PMID: 12376537 DOI: 10.1074/jbc.m208875200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The effectors of monomeric GTP-binding proteins can influence interactions with GTPase-activating proteins (GAPs) in two ways. In one case, effector and GAP binding to the GTP-binding protein is mutually exclusive. In another case, the GTP-binding protein bound to an effector is the substrate for the GTPase-activating protein. Here predictions for these two mechanisms were tested for the Arf1 effector GGA and ASAP family Arf GAPs. GGA inhibited Arf GAP activity of ASAP1, AGAP1, ARAP1, and Arf GAP1 and inhibited binding of Arf1.GTPgammaS to AGAP1 with K(i) values correlating with the K(d) for the GGA.Arf1 complex. ASAP1 blocked Arf1.GTPgammaS binding to GGA with a K(i) similar to the K(d) for the ASAP.Arf1.GTPgammaS complex. No interaction of GGA with ASAP1 was detected. Consistent with GGA sequestering Arf from GAPs, overexpression of GGA slowed the rate of Arf dissociation from the Golgi apparatus following treatment with brefeldin A. Mutational analysis revealed the amino-terminal alpha-helix and switch I of Arf1 contributed to interaction with both GGA and GAPs. These data exclude the mechanism previously documented for Arf GAP1/coatomer in which Arf1 is inactivated in a tripartite complex. Instead, termination of Arf1 signals mediated through GGA require that Arf1.GTP dissociates from GGA prior to interaction with GAP and consequent hydrolysis of GTP.
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Affiliation(s)
- Kerry M Jacques
- Laboratory of Cellular Oncology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892, USA
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48
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Crottet P, Meyer DM, Rohrer J, Spiess M. ARF1.GTP, tyrosine-based signals, and phosphatidylinositol 4,5-bisphosphate constitute a minimal machinery to recruit the AP-1 clathrin adaptor to membranes. Mol Biol Cell 2002; 13:3672-82. [PMID: 12388765 PMCID: PMC129974 DOI: 10.1091/mbc.e02-05-0309] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2002] [Revised: 07/09/2002] [Accepted: 07/16/2002] [Indexed: 11/11/2022] Open
Abstract
At the trans-Golgi network, clathrin coats containing AP-1 adaptor complexes are formed in an ARF1-dependent manner, generating vesicles transporting cargo proteins to endosomes. The mechanism of site-specific targeting of AP-1 and the role of cargo are poorly understood. We have developed an in vitro assay to study the recruitment of purified AP-1 adaptors to chemically defined liposomes presenting peptides corresponding to tyrosine-based sorting motifs. AP-1 recruitment was found to be dependent on myristoylated ARF1, GTP or nonhydrolyzable GTP-analogs, tyrosine signals, and small amounts of phosphoinositides, most prominently phosphatidylinositol 4,5-bisphosphate, in the absence of any additional cytosolic or membrane bound proteins. AP-1 from cytosol could be recruited to a tyrosine signal independently of the lipid composition, but the rate of recruitment was increased by phosphatidylinositol 4,5-bisphosphate. The results thus indicate that cargo proteins are involved in coat recruitment and that the local lipid composition contributes to specifying the site of vesicle formation.
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Affiliation(s)
- Pascal Crottet
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland
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49
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Doray B, Ghosh P, Griffith J, Geuze HJ, Kornfeld S. Cooperation of GGAs and AP-1 in packaging MPRs at the trans-Golgi network. Science 2002; 297:1700-3. [PMID: 12215646 DOI: 10.1126/science.1075327] [Citation(s) in RCA: 194] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The Golgi-localized, gamma-ear-containing, adenosine diphosphate ribosylation factor-binding proteins (GGAs) are multidomain proteins that bind mannose 6-phosphate receptors (MPRs) in the Golgi and have an essential role in lysosomal enzyme sorting. Here the GGAs and the coat protein adaptor protein-1 (AP-1) were shown to colocalize in clathrin-coated buds of the trans-Golgi networks of mouse L cells and human HeLa cells. Binding studies revealed a direct interaction between the hinge domains of the GGAs and the gamma-ear domain of AP-1. Further, AP-1 contained bound casein kinase-2 that phosphorylated GGA1 and GGA3, thereby causing autoinhibition. This could induce the directed transfer of the MPRs from GGAs to AP-1. MPRs that are defective in binding to GGAs are poorly incorporated into AP-1-containing clathrin-coated vesicles. Thus, the GGAs and AP-1 interact to package MPRs into AP-1-containing coated vesicles.
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Affiliation(s)
- Balraj Doray
- Department of Internal Medicine, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
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50
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Mansour M, Lee SY, Pohajdak B. The N-terminal coiled coil domain of the cytohesin/ARNO family of guanine nucleotide exchange factors interacts with the scaffolding protein CASP. J Biol Chem 2002; 277:32302-9. [PMID: 12052827 DOI: 10.1074/jbc.m202898200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cytohesin is a guanine nucleotide exchange factor that regulates members of the ADP-ribosylation factor (ARF) family of small GTPases. All of the members of the cytohesin family (including ARNO, ARNO3, and the newly characterized cytohesin-4) have a similar domain distribution consisting of a Sec7 homology domain, a pleckstrin homology domain, and an N-terminal coiled coil. In this study, we attempt to identify proteins that interact specifically with the coiled coil motif of cytohesin. Yeast two-hybrid screening of a B cell library using the cytohesin N terminus as bait, identified CASP, a scaffolding protein of previously unknown function, as a binding partner. CASP contains an internal coiled coil motif that is required for cytohesin binding both in vitro and in COS-1 cells. The specificity of the coiled coil of CASP is not restricted to cytohesin, however, because it is also capable of interacting with other members of the cytohesin/ARNO family, ARNO and ARNO3. In immunofluorescence experiments, CASP localizes to perinuclear tubulovesicular structures that are in close proximity to the Golgi. These structures remain relatively undisturbed when the cells are treated with brefeldin A. In epidermal growth factor-stimulated COS-1 cells overexpressing cytohesin and CASP, cytohesin recruits CASP to membrane ruffles, revealing a functional interaction between the two proteins. These observations collectively suggest that CASP is a scaffolding protein that facilitates the function of at least one member of the cytohesin/ARNO family in response to specific cellular stimuli.
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Affiliation(s)
- Marc Mansour
- Biology Department, Dalhousie University, Halifax, Nova Scotia B3H 4J1, Canada
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