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Awoniyi LO, Cunha DM, Sarapulov AV, Hernández-Pérez S, Runsala M, Tejeda-González B, Šuštar V, Balci MÖ, Petrov P, Mattila PK. B cell receptor-induced protein dynamics and the emerging role of SUMOylation revealed by proximity proteomics. J Cell Sci 2023; 136:jcs261119. [PMID: 37417469 PMCID: PMC10445728 DOI: 10.1242/jcs.261119] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 07/03/2023] [Indexed: 07/08/2023] Open
Abstract
Successful B cell activation, which is critical for high-affinity antibody production, is controlled by the B cell antigen receptor (BCR). However, we still lack a comprehensive protein-level view of the very dynamic multi-branched cellular events triggered by antigen binding. Here, we employed APEX2 proximity biotinylation to study antigen-induced changes, 5-15 min after receptor activation, at the vicinity of the plasma membrane lipid rafts, wherein BCR enriches upon activation. The data reveals dynamics of signaling proteins, as well as various players linked to the subsequent processes, such as actin cytoskeleton remodeling and endocytosis. Interestingly, our differential expression analysis identified dynamic responses in various proteins previously not linked to early B cell activation. We demonstrate active SUMOylation at the sites of BCR activation in various conditions and report its functional role in BCR signaling through the AKT and ERK1/2 axes.
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Affiliation(s)
- Luqman O. Awoniyi
- Institute of Biomedicine and MediCity Research Laboratories, University of Turku, 20014 Turku, Finland
- Turku Bioscience, University of Turku and Åbo Akademi University, 20520 Turku, Finland
- InFLAMES Research Flagship Center, University of Turku, 20014 Turku, Finland
| | - Diogo M. Cunha
- Institute of Biomedicine and MediCity Research Laboratories, University of Turku, 20014 Turku, Finland
- Turku Bioscience, University of Turku and Åbo Akademi University, 20520 Turku, Finland
- InFLAMES Research Flagship Center, University of Turku, 20014 Turku, Finland
| | - Alexey V. Sarapulov
- Institute of Biomedicine and MediCity Research Laboratories, University of Turku, 20014 Turku, Finland
- Turku Bioscience, University of Turku and Åbo Akademi University, 20520 Turku, Finland
- InFLAMES Research Flagship Center, University of Turku, 20014 Turku, Finland
| | - Sara Hernández-Pérez
- Institute of Biomedicine and MediCity Research Laboratories, University of Turku, 20014 Turku, Finland
- Turku Bioscience, University of Turku and Åbo Akademi University, 20520 Turku, Finland
- InFLAMES Research Flagship Center, University of Turku, 20014 Turku, Finland
| | - Marika Runsala
- Institute of Biomedicine and MediCity Research Laboratories, University of Turku, 20014 Turku, Finland
- Turku Bioscience, University of Turku and Åbo Akademi University, 20520 Turku, Finland
- InFLAMES Research Flagship Center, University of Turku, 20014 Turku, Finland
| | - Blanca Tejeda-González
- Institute of Biomedicine and MediCity Research Laboratories, University of Turku, 20014 Turku, Finland
- Turku Bioscience, University of Turku and Åbo Akademi University, 20520 Turku, Finland
- InFLAMES Research Flagship Center, University of Turku, 20014 Turku, Finland
| | - Vid Šuštar
- Institute of Biomedicine and MediCity Research Laboratories, University of Turku, 20014 Turku, Finland
| | - M. Özge Balci
- Institute of Biomedicine and MediCity Research Laboratories, University of Turku, 20014 Turku, Finland
- Turku Bioscience, University of Turku and Åbo Akademi University, 20520 Turku, Finland
- InFLAMES Research Flagship Center, University of Turku, 20014 Turku, Finland
| | - Petar Petrov
- Institute of Biomedicine and MediCity Research Laboratories, University of Turku, 20014 Turku, Finland
- Turku Bioscience, University of Turku and Åbo Akademi University, 20520 Turku, Finland
- InFLAMES Research Flagship Center, University of Turku, 20014 Turku, Finland
| | - Pieta K. Mattila
- Institute of Biomedicine and MediCity Research Laboratories, University of Turku, 20014 Turku, Finland
- Turku Bioscience, University of Turku and Åbo Akademi University, 20520 Turku, Finland
- InFLAMES Research Flagship Center, University of Turku, 20014 Turku, Finland
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2
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Weimershaus M, Carvalho C, Rignault R, Waeckel-Enee E, Dussiot M, van Endert P, Maciel TT, Hermine O. Mast cell-mediated inflammation relies on insulin-regulated aminopeptidase controlling cytokine export from the Golgi. J Allergy Clin Immunol 2023:S0091-6749(23)00090-8. [PMID: 36708814 DOI: 10.1016/j.jaci.2023.01.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 12/31/2022] [Accepted: 01/11/2023] [Indexed: 01/26/2023]
Abstract
BACKGROUND On activation, mast cells rapidly release preformed inflammatory mediators from large cytoplasmic granules via regulated exocytosis. This acute degranulation is followed by a late activation phase involving synthesis and secretion of cytokines, growth factors, and other inflammatory molecules via the constitutive pathway that remains ill defined. OBJECTIVE We investigated the role for an insulin-responsive vesicle-like endosomal compartment, marked by insulin-regulated aminopeptidase (IRAP), in the secretion of TNF-α and IL-6 in mast cells and macrophages. METHODS Murine knockout (KO) mouse models (IRAP-KO and kit-Wsh/sh) were used to study inflammatory disease models and to measure and mechanistically investigate cytokine secretion and degranulation in bone marrow-derived mast cells in vitro. RESULTS IRAP-KO mice are protected from TNF-α-dependent kidney injury and inflammatory arthritis. In the absence of IRAP, TNF-α and IL-6 but not IL-10 fail to be efficiently secreted. Moreover, chemical targeting of IRAP endosomes reduced proinflammatory cytokine secretion. Mechanistically, impaired TNF-α export from the Golgi and reduced colocalization of vesicle-associated membrane protein (VAMP) 3-positive TNF-α transport vesicles with syntaxin 4 (aka Stx4) was observed in IRAP-KO mast cells, while VAMP8-dependent exocytosis of secretory granules was facilitated. CONCLUSION IRAP plays a novel role in mast cell-mediated inflammation through the regulation of exocytic trafficking of cytokines.
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Affiliation(s)
- Mirjana Weimershaus
- Imagine Institute, Laboratory of Cellular and Molecular Mechanisms of Hematological Disorders and Therapeutic Implications, INSERM U1163, F-75015, Paris, France.
| | - Caroline Carvalho
- Imagine Institute, Laboratory of Cellular and Molecular Mechanisms of Hematological Disorders and Therapeutic Implications, INSERM U1163, F-75015, Paris, France
| | - Rachel Rignault
- Imagine Institute, Laboratory of Cellular and Molecular Mechanisms of Hematological Disorders and Therapeutic Implications, INSERM U1163, F-75015, Paris, France; Université de Paris Cité, Paris, France
| | | | - Michael Dussiot
- Imagine Institute, Laboratory of Cellular and Molecular Mechanisms of Hematological Disorders and Therapeutic Implications, INSERM U1163, F-75015, Paris, France; Université de Paris Cité, Paris, France; Laboratory of Excellence GR-Ex, Paris, France
| | - Peter van Endert
- INSERM UMR 1151, CNRS UMR 8253, Paris, France; Université de Paris Cité, Paris, France
| | - Thiago Trovati Maciel
- Imagine Institute, Laboratory of Cellular and Molecular Mechanisms of Hematological Disorders and Therapeutic Implications, INSERM U1163, F-75015, Paris, France; Laboratory of Excellence GR-Ex, Paris, France
| | - Olivier Hermine
- Imagine Institute, Laboratory of Cellular and Molecular Mechanisms of Hematological Disorders and Therapeutic Implications, INSERM U1163, F-75015, Paris, France; Université de Paris Cité, Paris, France; Hôpital Necker Enfants Malades, Paris, France; Laboratory of Excellence GR-Ex, Paris, France
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3
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Bogan JS. Ubiquitin-like processing of TUG proteins as a mechanism to regulate glucose uptake and energy metabolism in fat and muscle. Front Endocrinol (Lausanne) 2022; 13:1019405. [PMID: 36246906 PMCID: PMC9556833 DOI: 10.3389/fendo.2022.1019405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 09/06/2022] [Indexed: 12/02/2022] Open
Abstract
In response to insulin stimulation, fat and muscle cells mobilize GLUT4 glucose transporters to the cell surface to enhance glucose uptake. Ubiquitin-like processing of TUG (Aspscr1, UBXD9) proteins is a central mechanism to regulate this process. Here, recent advances in this area are reviewed. The data support a model in which intact TUG traps insulin-responsive "GLUT4 storage vesicles" at the Golgi matrix by binding vesicle cargoes with its N-terminus and matrix proteins with its C-terminus. Insulin stimulation liberates these vesicles by triggering endoproteolytic cleavage of TUG, mediated by the Usp25m protease. Cleavage occurs in fat and muscle cells, but not in fibroblasts or other cell types. Proteolytic processing of intact TUG generates TUGUL, a ubiquitin-like protein modifier, as the N-terminal cleavage product. In adipocytes, TUGUL modifies a single protein, the KIF5B kinesin motor, which carries GLUT4 and other vesicle cargoes to the cell surface. In muscle, this or another motor may be modified. After cleavage of intact TUG, the TUG C-terminal product is extracted from the Golgi matrix by the p97 (VCP) ATPase. In both muscle and fat, this cleavage product enters the nucleus, binds PPARγ and PGC-1α, and regulates gene expression to promote fatty acid oxidation and thermogenesis. The stability of the TUG C-terminal product is regulated by an Ate1 arginyltransferase-dependent N-degron pathway, which may create a feedback mechanism to control oxidative metabolism. Although it is now clear that TUG processing coordinates glucose uptake with other aspects of physiology and metabolism, many questions remain about how this pathway is regulated and how it is altered in metabolic disease in humans.
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Affiliation(s)
- Jonathan S. Bogan
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale School of Medicine, New Haven, CT, United States
- Department of Cell Biology, Yale School of Medicine, New Haven, CT, United States
- Yale Center for Molecular and Systems Metabolism, Yale School of Medicine, New Haven, CT, United States
- *Correspondence: Jonathan S. Bogan,
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4
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Weimershaus M, Mauvais FX, Evnouchidou I, Lawand M, Saveanu L, van Endert P. IRAP Endosomes Control Phagosomal Maturation in Dendritic Cells. Front Cell Dev Biol 2020; 8:585713. [PMID: 33425891 PMCID: PMC7793786 DOI: 10.3389/fcell.2020.585713] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 11/04/2020] [Indexed: 01/08/2023] Open
Abstract
Dendritic cells (DCs) contribute to the immune surveillance by sampling their environment through phagocytosis and endocytosis. We have previously reported that, rapidly following uptake of extracellular antigen into phagosomes or endosomes in DCs, a specialized population of storage endosomes marked by Rab14 and insulin-regulated aminopeptidase (IRAP) is recruited to the nascent antigen-containing compartment, thereby regulating its maturation and ultimately antigen cross-presentation to CD8+ T lymphocytes. Here, using IRAP–/– DCs, we explored how IRAP modulates phagosome maturation dynamics and cross-presentation. We find that in the absence of IRAP, phagosomes acquire more rapidly late endosomal markers, are more degradative, and show increased microbicidal activity. We also report evidence for a role of vesicle trafficking from the endoplasmic reticulum (ER)–Golgi intermediate compartment to endosomes for the formation or stability of the IRAP compartment. Moreover, we dissect the dual role of IRAP as a trimming peptidase and a critical constituent of endosome stability. Experiments using a protease-dead IRAP mutant and pharmacological IRAP inhibition suggest that IRAP expression but not proteolytic activity is required for the formation of storage endosomes and for DC-typical phagosome maturation, whereas proteolysis is required for fully efficient cross-presentation. These findings identify IRAP as a key factor in cross-presentation, trimming peptides to fit the major histocompatibility complex class-I binding site while preventing their destruction through premature phagosome maturation.
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Affiliation(s)
- Mirjana Weimershaus
- Institut National de la Santé et de la Recherche Médicale, Unité 1151, Université de Paris, Centre National de la Recherche Scientifique, UMR 8253, Paris, France
| | - François-Xavier Mauvais
- Institut National de la Santé et de la Recherche Médicale, Unité 1151, Université de Paris, Centre National de la Recherche Scientifique, UMR 8253, Paris, France
| | - Irini Evnouchidou
- Institut National de la Santé et de la Recherche Médicale, Unité 1151, Université de Paris, Centre National de la Recherche Scientifique, UMR 8253, Paris, France.,Inovarion, Paris, France
| | - Myriam Lawand
- Institut National de la Santé et de la Recherche Médicale, Unité 1151, Université de Paris, Centre National de la Recherche Scientifique, UMR 8253, Paris, France
| | - Loredana Saveanu
- Institut National de la Santé et de la Recherche Médicale, Unité 1151, Université de Paris, Centre National de la Recherche Scientifique, UMR 8253, Paris, France
| | - Peter van Endert
- Institut National de la Santé et de la Recherche Médicale, Unité 1151, Université de Paris, Centre National de la Recherche Scientifique, UMR 8253, Paris, France
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5
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Li DT, Habtemichael EN, Julca O, Sales CI, Westergaard XO, DeVries SG, Ruiz D, Sayal B, Bogan JS. GLUT4 Storage Vesicles: Specialized Organelles for Regulated Trafficking. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2019; 92:453-470. [PMID: 31543708 PMCID: PMC6747935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Fat and muscle cells contain a specialized, intracellular organelle known as the GLUT4 storage vesicle (GSV). Insulin stimulation mobilizes GSVs, so that these vesicles fuse at the cell surface and insert GLUT4 glucose transporters into the plasma membrane. This example is likely one instance of a broader paradigm for regulated, non-secretory exocytosis, in which intracellular vesicles are translocated in response to diverse extracellular stimuli. GSVs have been studied extensively, yet these vesicles remain enigmatic. Data support the view that in unstimulated cells, GSVs are present as a pool of preformed small vesicles, which are distinct from endosomes and other membrane-bound organelles. In adipocytes, GSVs contain specific cargoes including GLUT4, IRAP, LRP1, and sortilin. They are formed by membrane budding, involving sortilin and probably CHC22 clathrin in humans, but the donor compartment from which these vesicles form remains uncertain. In unstimulated cells, GSVs are trapped by TUG proteins near the endoplasmic reticulum - Golgi intermediate compartment (ERGIC). Insulin signals through two main pathways to mobilize these vesicles. Signaling by the Akt kinase modulates Rab GTPases to target the GSVs to the cell surface. Signaling by the Rho-family GTPase TC10α stimulates Usp25m-mediated TUG cleavage to liberate the vesicles from the Golgi. Cleavage produces a ubiquitin-like protein modifier, TUGUL, that links the GSVs to KIF5B kinesin motors to promote their movement to the cell surface. In obesity, attenuation of these processes results in insulin resistance and contributes to type 2 diabetes and may simultaneously contribute to hypertension and dyslipidemia in the metabolic syndrome.
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Affiliation(s)
- Don T. Li
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, Yale University, New Haven, CT,Department of Cell Biology, Yale University School of Medicine, Yale University, New Haven, CT
| | - Estifanos N. Habtemichael
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, Yale University, New Haven, CT
| | - Omar Julca
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, Yale University, New Haven, CT
| | - Chloe I. Sales
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, Yale University, New Haven, CT
| | - Xavier O. Westergaard
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, Yale University, New Haven, CT
| | - Stephen G. DeVries
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, Yale University, New Haven, CT
| | - Diana Ruiz
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, Yale University, New Haven, CT
| | - Bhavesh Sayal
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, Yale University, New Haven, CT
| | - Jonathan S. Bogan
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, Yale University, New Haven, CT,Department of Cell Biology, Yale University School of Medicine, Yale University, New Haven, CT,To whom all correspondence should be addressed: Jonathan S. Bogan, Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, P.O. Box 208020, New Haven, CT 06520-8020; Tel: 203-785-6319; Fax: 203-785-6462;
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6
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Bhatt JM, Hancock W, Meissner JM, Kaczmarczyk A, Lee E, Viktorova E, Ramanadham S, Belov GA, Sztul E. Promiscuity of the catalytic Sec7 domain within the guanine nucleotide exchange factor GBF1 in ARF activation, Golgi homeostasis, and effector recruitment. Mol Biol Cell 2019; 30:1523-1535. [PMID: 30943106 PMCID: PMC6724685 DOI: 10.1091/mbc.e18-11-0711] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The integrity of the Golgi and trans-Golgi network (TGN) is disrupted by brefeldin A (BFA), which inhibits the Golgi-localized BFA-sensitive factor (GBF1) and brefeldin A-inhibited guanine nucleotide-exchange factors (BIG1 and BIG2). Using a cellular replacement assay to assess GBF1 functionality without interference from the BIGs, we show that GBF1 alone maintains Golgi architecture; facilitates secretion; activates ADP-ribosylation factor (ARF)1, 3, 4, and 5; and recruits ARF effectors to Golgi membranes. Unexpectedly, GBF1 also supports TGN integrity and recruits numerous TGN-localized ARF effectors. The impact of the catalytic Sec7 domain (Sec7d) on GBF1 functionality was assessed by swapping it with the Sec7d from ARF nucleotide-binding site opener (ARNO)/cytohesin-2, a plasma membrane GEF reported to activate all ARFs. The resulting chimera (GBF1-ARNO-GBF1 [GARG]) targets like GBF1, supports Golgi/TGN architecture, and facilitates secretion. However, unlike GBF1, GARG activates all ARFs (including ARF6) at the Golgi/TGN and recruits additional ARF effectors to the Golgi/TGN. Our results have general implications: 1) GEF's targeting is independent of Sec7d, but Sec7d influence the GEF substrate specificity and downstream effector events; 2) all ARFs have access to all membranes, but are restricted in their distribution by the localization of their activating GEFs; and 3) effector association with membranes requires the coincidental presence of activated ARFs and specific membrane identifiers.
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Affiliation(s)
- Jay M Bhatt
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - William Hancock
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Justyna M Meissner
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Aneta Kaczmarczyk
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Eunjoo Lee
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Ekaterina Viktorova
- Department of Veterinary Medicine, Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, MD 20742
| | - Sasanka Ramanadham
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294.,Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL 35294
| | - George A Belov
- Department of Veterinary Medicine, Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, MD 20742
| | - Elizabeth Sztul
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294
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7
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Abstract
The Golgi apparatus is a central intracellular membrane-bound organelle with key functions in trafficking, processing, and sorting of newly synthesized membrane and secretory proteins and lipids. To best perform these functions, Golgi membranes form a unique stacked structure. The Golgi structure is dynamic but tightly regulated; it undergoes rapid disassembly and reassembly during the cell cycle of mammalian cells and is disrupted under certain stress and pathological conditions. In the past decade, significant amount of effort has been made to reveal the molecular mechanisms that regulate the Golgi membrane architecture and function. Here we review the major discoveries in the mechanisms of Golgi structure formation, regulation, and alteration in relation to its functions in physiological and pathological conditions to further our understanding of Golgi structure and function in health and diseases.
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Affiliation(s)
- Jie Li
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Erpan Ahat
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Yanzhuang Wang
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.
- Department of Neurology, University of Michigan School of Medicine, Ann Arbor, MI, USA.
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8
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Trávez A, Rabanal-Ruiz Y, López-Alcalá J, Molero-Murillo L, Díaz-Ruiz A, Guzmán-Ruiz R, Catalán V, Rodríguez A, Frühbeck G, Tinahones FJ, Gasman S, Vitale N, Jiménez-Gómez Y, Malagón MM. The caveolae-associated coiled-coil protein, NECC2, regulates insulin signalling in Adipocytes. J Cell Mol Med 2018; 22:5648-5661. [PMID: 30160359 PMCID: PMC6201366 DOI: 10.1111/jcmm.13840] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 07/10/2018] [Accepted: 07/13/2018] [Indexed: 02/06/2023] Open
Abstract
Adipocyte dysfunction in obesity is commonly associated with impaired insulin signalling in adipocytes and insulin resistance. Insulin signalling has been associated with caveolae, which are coated by large complexes of caveolin and cavin proteins, along with proteins with membrane-binding and remodelling properties. Here, we analysed the regulation and function of a component of caveolae involved in growth factor signalling in neuroendocrine cells, neuroendocrine long coiled-coil protein-2 (NECC2), in adipocytes. Studies in 3T3-L1 cells showed that NECC2 expression increased during adipogenesis. Furthermore, NECC2 co-immunoprecipitated with caveolin-1 (CAV1) and exhibited a distribution pattern similar to that of the components of adipocyte caveolae, CAV1, Cavin1, the insulin receptor and cortical actin. Interestingly, NECC2 overexpression enhanced insulin-activated Akt phosphorylation, whereas NECC2 downregulation impaired insulin-induced phosphorylation of Akt and ERK2. Finally, an up-regulation of NECC2 in subcutaneous and omental adipose tissue was found in association with human obesity and insulin resistance. This effect was also observed in 3T3-L1 adipocytes exposed to hyperglycaemia/hyperinsulinemia. Overall, the present study identifies NECC2 as a component of adipocyte caveolae that is regulated in response to obesity and associated metabolic complications, and supports the contribution of this protein as a molecular scaffold modulating insulin signal transduction at these membrane microdomains.
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Affiliation(s)
- Andrés Trávez
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Córdoba, Spain.,Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba, Spain.,Reina Sofía University Hospital, Córdoba, Spain.,CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Madrid, Spain
| | - Yoana Rabanal-Ruiz
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Córdoba, Spain.,Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba, Spain.,Reina Sofía University Hospital, Córdoba, Spain.,CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Madrid, Spain
| | - Jaime López-Alcalá
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Córdoba, Spain.,Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba, Spain.,Reina Sofía University Hospital, Córdoba, Spain
| | - Laura Molero-Murillo
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Córdoba, Spain.,Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba, Spain.,Reina Sofía University Hospital, Córdoba, Spain.,CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Madrid, Spain
| | - Alberto Díaz-Ruiz
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Córdoba, Spain.,Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba, Spain.,Reina Sofía University Hospital, Córdoba, Spain.,CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Madrid, Spain
| | - Rocío Guzmán-Ruiz
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Córdoba, Spain.,Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba, Spain.,Reina Sofía University Hospital, Córdoba, Spain.,CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Madrid, Spain
| | - Victoria Catalán
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Madrid, Spain.,Metabolic Research Laboratory, Department of Endocrinology & Nutrition, Clínica Universidad de Navarra, IdiSNA, Pamplona, Spain
| | - Amaia Rodríguez
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Madrid, Spain.,Metabolic Research Laboratory, Department of Endocrinology & Nutrition, Clínica Universidad de Navarra, IdiSNA, Pamplona, Spain
| | - Gema Frühbeck
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Madrid, Spain.,Metabolic Research Laboratory, Department of Endocrinology & Nutrition, Clínica Universidad de Navarra, IdiSNA, Pamplona, Spain
| | - Francisco J Tinahones
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Madrid, Spain.,Unidad de Gestion Clínica de Endocrinología y Nutrición, Laboratorio del Instituto de Investigación Biomédica de Málaga (IBIMA), Hospital Universitario de Málaga (Virgen de la Victoria), Universidad de Málaga, Málaga, Spain
| | - Stéphane Gasman
- Institut des Neurosciences Cellulaires et Intégratives (INCI), Centre National de la Recherche Scientifique (CNRS UPR 3212), Université de Strasbourg, Strasbourg, France
| | - Nicolas Vitale
- Institut des Neurosciences Cellulaires et Intégratives (INCI), Centre National de la Recherche Scientifique (CNRS UPR 3212), Université de Strasbourg, Strasbourg, France
| | - Yolanda Jiménez-Gómez
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Córdoba, Spain.,Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba, Spain.,Reina Sofía University Hospital, Córdoba, Spain
| | - María M Malagón
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Córdoba, Spain.,Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba, Spain.,Reina Sofía University Hospital, Córdoba, Spain.,CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Madrid, Spain
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9
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Gilbert CE, Sztul E, Machamer CE. Commonly used trafficking blocks disrupt ARF1 activation and the localization and function of specific Golgi proteins. Mol Biol Cell 2018; 29:937-947. [PMID: 29467256 PMCID: PMC5896932 DOI: 10.1091/mbc.e17-11-0622] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Cold temperature blocks used to synchronize protein trafficking inhibit GBF1 function, leading to a decrease in ARF1-GTP levels and mislocalization of the ARF1 effector golgin-160. Several other, but not all, Golgi proteins including ARL1 also mislocalize. ARF1 activity and golgin-160 localization require more than 30 min to recover from these blocks. ADP-ribosylation factor (ARF) proteins are key regulators of the secretory pathway. ARF1, through interacting with its effectors, regulates protein trafficking by facilitating numerous events at the Golgi. One unique ARF1 effector is golgin-160, which promotes the trafficking of only a specific subset of cargo proteins through the Golgi. While studying this role of golgin-160, we discovered that commonly used cold temperature blocks utilized to synchronize cargo trafficking (20 and 16°C) caused golgin-160 dispersal from Golgi membranes. Here, we show that the loss of golgin-160 localization correlates with a decrease in the levels of activated ARF1, and that golgin-160 dispersal can be prevented by expression of a GTP-locked ARF1 mutant. Overexpression of the ARF1 activator Golgi brefeldin A–resistant guanine nucleotide exchange factor 1 (GBF1) did not prevent golgin-160 dispersal, suggesting that GBF1 may be nonfunctional at lower temperatures. We further discovered that several other Golgi resident proteins had altered localization at lower temperatures, including proteins recruited by ARF-like GTPase 1 (ARL1), a small GTPase that also became dispersed in the cold. Although cold temperature blocks are useful for synchronizing cargo trafficking through the Golgi, our data indicate that caution must be taken when interpreting results from these assays.
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Affiliation(s)
- Catherine E Gilbert
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Elizabeth Sztul
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35924
| | - Carolyn E Machamer
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
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10
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Ahmed A, Arshad M, Malik A, Parveen S, Alsenaidy AM. Camelus dromedarius glucose transporter 4: in silico analysis, cloning, expression, purification and characterisation in E. coli. Arch Physiol Biochem 2017; 123:254-264. [PMID: 28440667 DOI: 10.1080/13813455.2017.1312460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Camels have exceptional carbohydrate metabolism as their plasma glucose level is high and have low whole body insulin sensitivity, similar to that observed in type 2 diabetes patients. We aimed at studing an important component of insulin signalling pathway, the GLUT4, in camel. Camelus dromedarius GLUT4 (CdGLUT4) CDS is 1530 nucleotide in length that encodes for a 55KDa protein. CdGLUT4 has 23 amino acid substitutions and 3N-glycosylation sites, compared to 2 in Human GLUT4. 3 D structures of CdGLUT4 and HsGLUT4 generated by homology modelling revealed conservation of characteristic signature motifs. CdGLUT4 was cloned and expressed optimally in C43(DE3)pLysS strain and maximum detergent solubility was observed in n-Dodecyl-β-d-maltopyranoside. These preliminary data provide information on residual differences between CdGLUT4 and HsGLUT4 that may be responsible for camel's unique glucose metabolism. These differences are postulated to assist in designing and development of efficacious GLUT4 that might help in management of diabetic patients.
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Affiliation(s)
- Anwar Ahmed
- a Protein Research Chair, Department of Biochemistry, College of Science , King Saud University , Riyadh , Saudi Arabia
- b Centre of Excellence in Biotechnology Research, Department of Biochemistry, College of Science , King Saud University , Riyadh , Saudi Arabia
| | - Mohammed Arshad
- a Protein Research Chair, Department of Biochemistry, College of Science , King Saud University , Riyadh , Saudi Arabia
| | - Ajamaluddin Malik
- a Protein Research Chair, Department of Biochemistry, College of Science , King Saud University , Riyadh , Saudi Arabia
| | - Shama Parveen
- c Centre for Interdisciplinary Research in Basic Sciences , Jamia Millia Islamia , New Delhi , India
| | - Abdulrahman M Alsenaidy
- a Protein Research Chair, Department of Biochemistry, College of Science , King Saud University , Riyadh , Saudi Arabia
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11
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Talantikite M, Berenguer M, Gonzalez T, Alessi MC, Poggi M, Peiretti F, Govers R. The first intracellular loop of GLUT4 contains a retention motif. J Cell Sci 2016; 129:2273-84. [DOI: 10.1242/jcs.183525] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 04/20/2016] [Indexed: 01/02/2023] Open
Abstract
Glucose transporter GLUT4 plays a major role in glucose homeostasis and is efficiently retained intracellularly in adipocytes and myocytes. To simplify the analysis of its retention, various intracellular GLUT4 domains were fused individually to reporter molecules. Of the four short cytoplasmic loops of GLUT4, only the first nine-residue-long loop conferred intracellular retention of truncated forms of the transferrin receptor and CD4 in adipocytes. In contrast, the same loop of GLUT1 was without effect. The reporter molecules to which the first loop of GLUT4 was fused localized, unlike GLUT4, to the TGN, possibly explaining why these molecules did not respond to insulin. The retention induced by the GLUT4 loop was specific to adipocytes as it did not induce retention in preadipocytes. Of the SQWLGRKRA sequence that constitutes this loop, mutation of either the tryptophan or lysine residue abrogated reporter retention. Mutation of these residues individually into alanines in the full-length GLUT4 molecule resulted in a decreased retention for GLUT4-W105A. We conclude that the first intracellular loop of GLUT4 contains retention motif WLGRK, in which Trp105 plays a prominent role.
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Affiliation(s)
- Maya Talantikite
- Inserm U1062, INRA1260, Aix Marseille University, Faculty of Medicine, Marseille F-13385, France
| | - Marion Berenguer
- Inserm U895, Mediterranean Research Center for Molecular Medicine (C3M), Nice, F-06204, France
| | - Teresa Gonzalez
- Inserm U1062, INRA1260, Aix Marseille University, Faculty of Medicine, Marseille F-13385, France
| | - Marie Christine Alessi
- Inserm U1062, INRA1260, Aix Marseille University, Faculty of Medicine, Marseille F-13385, France
| | - Marjorie Poggi
- Inserm U1062, INRA1260, Aix Marseille University, Faculty of Medicine, Marseille F-13385, France
| | - Franck Peiretti
- Inserm U1062, INRA1260, Aix Marseille University, Faculty of Medicine, Marseille F-13385, France
| | - Roland Govers
- Inserm U1062, INRA1260, Aix Marseille University, Faculty of Medicine, Marseille F-13385, France
- Inserm U895, Mediterranean Research Center for Molecular Medicine (C3M), Nice, F-06204, France
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12
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Abstract
The Golgi complex is a central organelle of the secretory pathway where sorting and processing of cargo occurs. While Golgi structure is important for the efficient processing of secretory cargo, the unusual organization suggests additional potential functions. The Golgi is disassembled after various cellular stresses, and we hypothesize that Golgi disassembly activates a stress signaling pathway. This pathway would function to correct the stress if possible, with irreparable stress resulting in apoptosis. Neurons appear to be particularly sensitive to Golgi stress; early disassembly of the organelle correlates with many neurodegenerative diseases. Here, Golgi stress and potential signaling pathways to the nucleus are reviewed.
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Affiliation(s)
- Carolyn E Machamer
- Department of Cell Biology, Johns Hopkins University School of Medicine Baltimore, MD, USA
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13
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Joshi G, Bekier ME, Wang Y. Golgi fragmentation in Alzheimer's disease. Front Neurosci 2015; 9:340. [PMID: 26441511 PMCID: PMC4585163 DOI: 10.3389/fnins.2015.00340] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 09/08/2015] [Indexed: 11/24/2022] Open
Abstract
The Golgi apparatus is an essential cellular organelle for post-translational modifications, sorting, and trafficking of membrane and secretory proteins. Proper functionality of the Golgi requires the formation of its unique cisternal-stacking morphology. The Golgi structure is disrupted in a variety of neurodegenerative diseases, suggesting a common mechanism and contribution of Golgi defects in neurodegenerative disorders. A recent study on Alzheimer's disease (AD) revealed that phosphorylation of the Golgi stacking protein GRASP65 disrupts its function in Golgi structure formation, resulting in Golgi fragmentation. Inhibiting GRASP65 phosphorylation restores the Golgi morphology from Aβ-induced fragmentation and reduces Aβ production. Perturbing Golgi structure and function in neurons may directly impact trafficking, processing, and sorting of a variety of proteins essential for synaptic and dendritic integrity. Therefore, Golgi defects may ultimately promote the development of AD. In the current review, we focus on the cellular impact of impaired Golgi morphology and its potential relationship to AD disease development.
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Affiliation(s)
- Gunjan Joshi
- Department of Molecular, Cellular and Developmental Biology, University of Michigan Ann Arbor, MI, USA
| | - Michael E Bekier
- Department of Molecular, Cellular and Developmental Biology, University of Michigan Ann Arbor, MI, USA
| | - Yanzhuang Wang
- Department of Molecular, Cellular and Developmental Biology, University of Michigan Ann Arbor, MI, USA ; Department of Neurology, University of Michigan School of Medicine Ann Arbor, MI, USA
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14
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Belman JP, Bian RR, Habtemichael EN, Li DT, Jurczak MJ, Alcázar-Román A, McNally LJ, Shulman GI, Bogan JS. Acetylation of TUG protein promotes the accumulation of GLUT4 glucose transporters in an insulin-responsive intracellular compartment. J Biol Chem 2015; 290:4447-63. [PMID: 25561724 DOI: 10.1074/jbc.m114.603977] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin causes the exocytic translocation of GLUT4 glucose transporters to stimulate glucose uptake in fat and muscle. Previous results support a model in which TUG traps GLUT4 in intracellular, insulin-responsive vesicles termed GLUT4 storage vesicles (GSVs). Insulin triggers TUG cleavage to release the GSVs; GLUT4 then recycles through endosomes during ongoing insulin exposure. The TUG C terminus binds a GSV anchoring site comprising Golgin-160 and possibly other proteins. Here, we report that the TUG C terminus is acetylated. The TUG C-terminal peptide bound the Golgin-160-associated protein, ACBD3 (acyl-CoA-binding domain-containing 3), and acetylation reduced binding of TUG to ACBD3 but not to Golgin-160. Mutation of the acetylated residues impaired insulin-responsive GLUT4 trafficking in 3T3-L1 adipocytes. ACBD3 overexpression enhanced the translocation of GSV cargos, GLUT4 and insulin-regulated aminopeptidase (IRAP), and ACBD3 was required for intracellular retention of these cargos in unstimulated cells. Sirtuin 2 (SIRT2), a NAD(+)-dependent deacetylase, bound TUG and deacetylated the TUG peptide. SIRT2 overexpression reduced TUG acetylation and redistributed GLUT4 and IRAP to the plasma membrane in 3T3-L1 adipocytes. Mutation of the acetylated residues in TUG abrogated these effects. In mice, SIRT2 deletion increased TUG acetylation and proteolytic processing. During glucose tolerance tests, glucose disposal was enhanced in SIRT2 knock-out mice, compared with wild type controls, without any effect on insulin concentrations. Together, these data support a model in which TUG acetylation modulates its interaction with Golgi matrix proteins and is regulated by SIRT2. Moreover, acetylation of TUG enhances its function to trap GSVs within unstimulated cells and enhances insulin-stimulated glucose uptake.
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Affiliation(s)
- Jonathan P Belman
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine, Department of Cell Biology
| | - Rachel R Bian
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine
| | | | - Don T Li
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine
| | - Michael J Jurczak
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine
| | - Abel Alcázar-Román
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine
| | - Leah J McNally
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine
| | - Gerald I Shulman
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine, Department of Cellular and Molecular Physiology, and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06520-8020
| | - Jonathan S Bogan
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine, Department of Cell Biology,
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15
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Govers R. Molecular mechanisms of GLUT4 regulation in adipocytes. DIABETES & METABOLISM 2014; 40:400-10. [DOI: 10.1016/j.diabet.2014.01.005] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 01/24/2014] [Accepted: 01/26/2014] [Indexed: 01/28/2023]
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16
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Abstract
Insulin regulates glucose uptake by controlling the subcellular location of GLUT4 glucose transporters. GLUT4 is sequestered within fat and muscle cells during low-insulin states, and is translocated to the cell surface upon insulin stimulation. The TUG protein is a functional tether that sequesters GLUT4 at the Golgi matrix. To stimulate glucose uptake, insulin triggers TUG endoproteolytic cleavage. Cleavage accounts for a large proportion of the acute effect of insulin to mobilize GLUT4 to the cell surface. During ongoing insulin exposure, endocytosed GLUT4 recycles to the plasma membrane directly from endosomes, and bypasses a TUG-regulated trafficking step. Insulin acts through the TC10α GTPase and its effector protein, PIST, to stimulate TUG cleavage. This action is coordinated with insulin signals through AS160/Tbc1D4 and Tbc1D1 to modulate Rab GTPases, and with other signals to direct overall GLUT4 targeting. Data support the idea that the N-terminal TUG cleavage product, TUGUL, functions as a novel ubiquitin-like protein modifier to facilitate GLUT4 movement to the cell surface. The C-terminal TUG cleavage product is extracted from the Golgi matrix, which vacates an "anchoring" site to permit subsequent cycles of GLUT4 retention and release. Together, GLUT4 vesicle translocation and TUG cleavage may coordinate glucose uptake with physiologic effects of other proteins present in the GLUT4-containing vesicles, and with potential additional effects of the TUG C-terminal product. Understanding this TUG pathway for GLUT4 retention and release will shed light on the regulation of glucose uptake and the pathogenesis of type 2 diabetes.
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Affiliation(s)
- Jonathan P Belman
- Section of Endocrinology and Metabolism, Department of Internal Medicine, and Department of Cell Biology, Yale University School of Medicine, 333 Cedar Street, Box 208020, New Haven, CT, 06520-8020, USA
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17
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Gilbert CE, Zuckerman DM, Currier PL, Machamer CE. Three basic residues of intracellular loop 3 of the beta-1 adrenergic receptor are required for golgin-160-dependent trafficking. Int J Mol Sci 2014; 15:2929-45. [PMID: 24566136 PMCID: PMC3958891 DOI: 10.3390/ijms15022929] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 01/24/2014] [Accepted: 02/12/2014] [Indexed: 12/14/2022] Open
Abstract
Golgin-160 is a member of the golgin family of proteins, which have been implicated in the maintenance of Golgi structure and in vesicle tethering. Golgin-160 is atypical; it promotes post-Golgi trafficking of specific cargo proteins, including the β-1 adrenergic receptor (β1AR), a G protein-coupled receptor. Here we show that golgin-160 binds directly to the third intracellular loop of β1AR and that this binding depends on three basic residues in this loop. Mutation of the basic residues does not affect trafficking of β1AR from the endoplasmic reticulum through the Golgi complex, but results in reduced steady-state levels at the plasma membrane. We hypothesize that golgin-160 promotes incorporation of β1AR into specific transport carriers at the trans-Golgi network to ensure efficient delivery to the cell surface. These results add to our understanding of the biogenesis of β1AR, and suggest a novel point of regulation for its delivery to the plasma membrane.
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Affiliation(s)
- Catherine E Gilbert
- Department of Cell Biology, Johns Hopkins University School of Medicine, 725 N. Wolfe St., Baltimore, MD 21205, USA.
| | - David M Zuckerman
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe St., Baltimore, MD 21205, USA.
| | - Pamela L Currier
- Department of Cell Biology, Johns Hopkins University School of Medicine, 725 N. Wolfe St., Baltimore, MD 21205, USA.
| | - Carolyn E Machamer
- Department of Cell Biology, Johns Hopkins University School of Medicine, 725 N. Wolfe St., Baltimore, MD 21205, USA.
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18
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Abstract
GLUT4 is regulated by its intracellular localization. In the absence of insulin, GLUT4 is efficiently retained intracellularly within storage compartments in muscle and fat cells. Upon insulin stimulation (and contraction in muscle), GLUT4 translocates from these compartments to the cell surface where it transports glucose from the extracellular milieu into the cell. Its implication in insulin-regulated glucose uptake makes GLUT4 not only a key player in normal glucose homeostasis but also an important element in insulin resistance and type 2 diabetes. Nevertheless, how GLUT4 is retained intracellularly and how insulin acts on this retention mechanism is largely unclear. In this review, the current knowledge regarding the various molecular processes that govern GLUT4 physiology is discussed as well as the questions that remain.
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19
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Woody S, Stall R, Ramos J, Patel YM. Regulation of myosin light chain kinase during insulin-stimulated glucose uptake in 3T3-L1 adipocytes. PLoS One 2013; 8:e77248. [PMID: 24116218 PMCID: PMC3792908 DOI: 10.1371/journal.pone.0077248] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 09/09/2013] [Indexed: 11/25/2022] Open
Abstract
Myosin II (MyoII) is required for insulin-responsive glucose transporter 4 (GLUT4)-mediated glucose uptake in 3T3-L1 adipocytes. Our previous studies have shown that insulin signaling stimulates phosphorylation of the regulatory light chain (RLC) of MyoIIA via myosin light chain kinase (MLCK). The experiments described here delineate upstream regulators of MLCK during insulin-stimulated glucose uptake. Since 3T3-L1 adipocytes express two MyoII isoforms, we wanted to determine which isoform was required for insulin-stimulated glucose uptake. Using a siRNA approach, we demonstrate that a 60% decrease in MyoIIA protein expression resulted in a 40% inhibition of insulin-stimulated glucose uptake. We also show that insulin signaling stimulates the phosphorylation of MLCK. We further show that MLCK can be activated by calcium as well as signaling pathways. We demonstrate that adipocytes treated with the calcium chelating agent, 1,2-b (iso-aminophenoxy) ethane-N,N,N',N'-tetra acetic acid, (BAPTA) (in the presence of insulin) impaired the insulin-induced phosphorylation of MLCK by 52% and the RLC of MyoIIA by 45% as well as impairing the recruitment of MyoIIA to the plasma membrane when compared to cells treated with insulin alone. We further show that the calcium ionophore, A23187 alone stimulated the phosphorylation of MLCK and the RLC associated with MyoIIA to the same extent as insulin. To identify signaling pathways that might regulate MLCK, we examined ERK and CaMKII. Inhibition of ERK2 impaired phosphorylation of MLCK and insulin-stimulated glucose uptake. In contrast, while inhibition of CaMKII did inhibit phosphorylation of the RLC associated with MyoIIA, inhibition of CAMKIIδ did not impair MLCK phosphorylation or translocation to the plasma membrane or glucose uptake. Collectively, our results are the first to delineate a role for calcium and ERK in the activation of MLCK and thus MyoIIA during insulin-stimulated glucose uptake in 3T3-L1 adipocytes.
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Affiliation(s)
- Shelly Woody
- Department of Biology, University of North Carolina at Greensboro, Greensboro, North Carolina, United States of America
| | - Richard Stall
- Department of Biology, University of North Carolina at Greensboro, Greensboro, North Carolina, United States of America
| | - Joseph Ramos
- Department of Biology, University of North Carolina at Greensboro, Greensboro, North Carolina, United States of America
| | - Yashomati M. Patel
- Department of Biology, University of North Carolina at Greensboro, Greensboro, North Carolina, United States of America
- * E-mail:
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20
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Löffler MG, Birkenfeld AL, Philbrick KM, Belman JP, Habtemichael EN, Booth CJ, Castorena CM, Choi CS, Jornayvaz FR, Gassaway BM, Lee HY, Cartee GD, Philbrick W, Shulman GI, Samuel VT, Bogan JS. Enhanced fasting glucose turnover in mice with disrupted action of TUG protein in skeletal muscle. J Biol Chem 2013; 288:20135-50. [PMID: 23744065 DOI: 10.1074/jbc.m113.458075] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin stimulates glucose uptake in 3T3-L1 adipocytes in part by causing endoproteolytic cleavage of TUG (tether containing a ubiquitin regulatory X (UBX) domain for glucose transporter 4 (GLUT4)). Cleavage liberates intracellularly sequestered GLUT4 glucose transporters for translocation to the cell surface. To test the role of this regulation in muscle, we used mice with muscle-specific transgenic expression of a truncated TUG fragment, UBX-Cter. This fragment causes GLUT4 translocation in unstimulated 3T3-L1 adipocytes. We predicted that transgenic mice would have GLUT4 translocation in muscle during fasting. UBX-Cter expression caused depletion of PIST (PDZ domain protein interacting specifically with TC10), which transmits an insulin signal to TUG. Whereas insulin stimulated TUG proteolysis in control muscles, proteolysis was constitutive in transgenic muscles. Fasting transgenic mice had decreased plasma glucose and insulin concentrations compared with controls. Whole-body glucose turnover was increased during fasting but not during hyperinsulinemic clamp studies. In muscles with the greatest UBX-Cter expression, 2-deoxyglucose uptake during fasting was similar to that in control muscles during hyperinsulinemic clamp studies. Fasting transgenic mice had increased muscle glycogen, and GLUT4 targeting to T-tubule fractions was increased 5.7-fold. Whole-body oxygen consumption (VO2), carbon dioxide production (VCO2), and energy expenditure were increased by 12-13%. After 3 weeks on a high fat diet, the decreased fasting plasma glucose in transgenic mice compared with controls was more marked, and increased glucose turnover was not observed; the transgenic mice continued to have an increased metabolic rate. We conclude that insulin stimulates TUG proteolysis to translocate GLUT4 in muscle, that this pathway impacts systemic glucose homeostasis and energy metabolism, and that the effects of activating this pathway are maintained during high fat diet-induced insulin resistance in mice.
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Affiliation(s)
- Michael G Löffler
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520-8020, USA
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21
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Sadler JBA, Bryant NJ, Gould GW, Welburn CR. Posttranslational modifications of GLUT4 affect its subcellular localization and translocation. Int J Mol Sci 2013; 14:9963-78. [PMID: 23665900 PMCID: PMC3676823 DOI: 10.3390/ijms14059963] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 05/02/2013] [Accepted: 05/02/2013] [Indexed: 01/05/2023] Open
Abstract
The facilitative glucose transporter type 4 (GLUT4) is expressed in adipose and muscle and plays a vital role in whole body glucose homeostasis. In the absence of insulin, only ~1% of cellular GLUT4 is present at the plasma membrane, with the vast majority localizing to intracellular organelles. GLUT4 is retained intracellularly by continuous trafficking through two inter-related cycles. GLUT4 passes through recycling endosomes, the trans Golgi network and an insulin-sensitive intracellular compartment, termed GLUT4-storage vesicles or GSVs. It is from GSVs that GLUT4 is mobilized to the cell surface in response to insulin, where it increases the rate of glucose uptake into the cell. As with many physiological responses to external stimuli, this regulated trafficking event involves multiple posttranslational modifications. This review outlines the roles of posttranslational modifications of GLUT4 on its function and insulin-regulated trafficking.
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Affiliation(s)
| | - Nia J. Bryant
- Institute of Molecular, Cell and Systems Biology, Davidson Building, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK; E-Mails: (J.B.A.S.); (N.J.B.); (G.W.G.)
| | - Gwyn W. Gould
- Institute of Molecular, Cell and Systems Biology, Davidson Building, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK; E-Mails: (J.B.A.S.); (N.J.B.); (G.W.G.)
| | - Cassie R. Welburn
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +44-141-330-6454; Fax: +44-141-330-5481
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22
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Darido C, Jane SM. Golgi Feels Its Own Wound. Adv Wound Care (New Rochelle) 2013; 2:87-92. [PMID: 24527331 DOI: 10.1089/wound.2011.0352] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Indexed: 01/28/2023] Open
Abstract
SIGNIFICANCE The Golgi apparatus is essential for protein processing, sorting, and transport. Processing includes carbohydrate modifications and proteolytic cleavage, and transport can involve secretion from the cell or relocation to a specific cellular compartment. Rapid and synchronized reorientation of the Golgi in migrating cells is thought to facilitate polarized secretion, providing membrane and secreted products to the proximal plasma membrane. This function is a fundamental process in cell motility. Whether the Golgi structure and positioning is functionally required for directed secretion and polarity in cell migration responses, such as wound healing, is yet to be elucidated. RECENT ADVANCES : Exciting recent analysis examined the effects of perturbed Golgi positioning without disruption of microtubular or actin cytoskeleton assembly or protein secretion, in the context of cellular polarity and directional migration in wound repair. This was achieved by Yadav et al. (2009) through depletion of Golgin-160 or GMAP210 (Golgi microtubule associated protein of 210 kDa), which resulted in fragmentation and dispersal of Golgi without altering secretion kinetics. As a consequence, the direction of secretion, cell polarization, and cell migration in response to wounding were severely impaired. Thus, in response to a scratch wound, cell polarity requires peri-centrosomal positioning of the Golgi apparatus, implying that after initiation by a polarity cue there is a dependence on the Golgi's directed secretion to maintain the polarized state that facilitates cell migration. CRITICAL ISSUES Golgi peri-centrosomal positioning can now be included among the growing list of cellular processes and signaling pathways that are critical for establishment of cellular polarity in response to external stimuli-a key feature of wound repair. FUTURE DIRECTIONS A complete understanding of the function of Golgi components in motility merits attractive avenues for future investigations that will ultimately bring regulators of Golgi into the clinic whereby treatment of skin-related disorders will greatly benefit.
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Affiliation(s)
| | - Stephen M. Jane
- Alfred Hospital, Prahran, Australia
- Department of Medicine, Monash University Central Clinical School, Prahran, Australia
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23
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Bentson LF, Agbor VA, Agbor LN, Lopez AC, Nfonsam LE, Bornstein SS, Handel MA, Linder CC. New point mutation in Golga3 causes multiple defects in spermatogenesis. Andrology 2013; 1:440-50. [PMID: 23495255 DOI: 10.1111/j.2047-2927.2013.00070.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 01/03/2013] [Accepted: 01/14/2013] [Indexed: 12/17/2022]
Abstract
Mice with repro27 exhibit fully penetrant male-specific infertility associated with a nonsense mutation in the golgin subfamily A member 3 gene (Golga3). GOLGA3 is a Golgi complex-associated protein implicated in protein trafficking, apoptosis, positioning of the Golgi and spermatogenesis. In repro27 mutant mice, a point mutation in exon 18 of the Golga3 gene that inserts a pre-mature termination codon leads to an absence of GOLGA3 protein expression. GOLGA3 protein was undetectable in the brain, heart and liver in both mutant and control mice. Although spermatogenesis in Golga3(repro27) mutant mice appears to initiate normally, development is disrupted in late meiosis during the first wave of spermatogenesis, leading to significant germ cell loss between 15 and 18 days post-partum (dpp). Terminal Deoxynucleotidyl Transferase dUTP-mediated Nick End Labeling analysis showed elevated DNA fragmentation in meiotic germ cells by 12 dpp, suggesting apoptosis as a mechanism of germ cell loss. The few surviving post-meiotic round spermatids exhibited abnormal spermiogenesis with defects in acrosome formation, head and tail development and extensive vacuolization in the seminiferous epithelium. Analysis of epididymal spermatozoa showed significantly low sperm concentration and motility and in vitro fertilization with mutant spermatozoa was unsuccessful. Golga3(repro27) mice lack GOLGA3 protein and thus provide an in vivo tool to aid in deciphering the role of GOLGA3 in Golgi complex positioning, cargo trafficking and apoptosis signalling in male germ cells.
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Affiliation(s)
- L F Bentson
- Department of Biology and Chemistry, New Mexico Highlands University, Las Vegas, NM 87701, USA
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Yadav S, Puthenveedu MA, Linstedt AD. Golgin160 recruits the dynein motor to position the Golgi apparatus. Dev Cell 2012; 23:153-65. [PMID: 22814606 DOI: 10.1016/j.devcel.2012.05.023] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Revised: 04/19/2012] [Accepted: 05/29/2012] [Indexed: 11/26/2022]
Abstract
Membrane motility is a fundamental characteristic of all eukaryotic cells. One of the best-known examples is that of the mammalian Golgi apparatus, where constant inward movement of Golgi membranes results in its characteristic position near the centrosome. While it is clear that the minus-end-directed motor dynein is required for this process, the mechanism and regulation of dynein recruitment to Golgi membranes remains unknown. Here, we show that the Golgi protein golgin160 recruits dynein to Golgi membranes. This recruitment confers centripetal motility to membranes and is regulated by the GTPase Arf1. Further, during cell division, motor association with membranes is regulated by the dissociation of the receptor-motor complex from membranes. These results identify a cell-cycle-regulated membrane receptor for a molecular motor and suggest a mechanistic basis for achieving the dramatic changes in organelle positioning seen during cell division.
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Affiliation(s)
- Smita Yadav
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
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25
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Deciphering the role of GLUT4 N-glycosylation in adipocyte and muscle cell models. Biochem J 2012; 445:265-73. [DOI: 10.1042/bj20120232] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
GLUT4 (glucose transporter 4) is responsible for the insulin-induced uptake of glucose by muscle and fat cells. In non-stimulated (basal) cells, GLUT4 is retained intracellularly, whereas insulin stimulation leads to its translocation from storage compartments towards the cell surface. How GLUT4 is retained intracellularly is largely unknown. Previously, aberrant GLUT4 N-glycosylation has been linked to increased basal cell-surface levels, while N-glycosylation-deficient GLUT4 was found to be quickly degraded. As recycling and degradation of GLUT4 are positively correlated, we hypothesized that incorrect N-glycosylation of GLUT4 might reduce its intracellular retention, resulting in an increased cell-surface recycling, in increased basal cell-surface levels, and in enhanced GLUT4 degradation. In the present study, we have investigated N-glycosylation-deficient GLUT4 in detail in 3T3-L1 preadipocytes, 3T3-L1 adipocytes and L6 myoblasts. We have found no alterations in retention, insulin response, internalization or glucose transport activity. Degradation of the mutant molecule was increased, although once present at the cell surface, its degradation was identical with that of wild-type GLUT4. Our findings indicate that N-glycosylation is important for efficient trafficking of GLUT4 to its proper compartments, but once the transporter has arrived there, N-glycosylation plays no further major role in its intracellular trafficking, nor in its functional activity.
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Bogan JS, Rubin BR, Yu C, Löffler MG, Orme CM, Belman JP, McNally LJ, Hao M, Cresswell JA. Endoproteolytic cleavage of TUG protein regulates GLUT4 glucose transporter translocation. J Biol Chem 2012; 287:23932-47. [PMID: 22610098 DOI: 10.1074/jbc.m112.339457] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To promote glucose uptake into fat and muscle cells, insulin causes the translocation of GLUT4 glucose transporters from intracellular vesicles to the cell surface. Previous data support a model in which TUG traps GLUT4-containing vesicles and tethers them intracellularly in unstimulated cells and in which insulin mobilizes this pool of vesicles by releasing this tether. Here we show that TUG undergoes site-specific endoproteolytic cleavage, which separates a GLUT4-binding, N-terminal region of TUG from a C-terminal region previously suggested to bind an intracellular anchor. Cleavage is accelerated by insulin stimulation in 3T3-L1 adipocytes and is highly dependent upon adipocyte differentiation. The N-terminal TUG cleavage product has properties of a novel 18-kDa ubiquitin-like modifier, which we call TUGUL. The C-terminal product is observed at the expected size of 42 kDa and also as a 54-kDa form that is released from membranes into the cytosol. In transfected cells, intact TUG links GLUT4 to PIST and also binds Golgin-160 through its C-terminal region. PIST is an effector of TC10α, a GTPase previously shown to transmit an insulin signal required for GLUT4 translocation, and we show using RNAi that TC10α is required for TUG proteolytic processing. Finally, we demonstrate that a cleavage-resistant form of TUG does not support highly insulin-responsive GLUT4 translocation or glucose uptake in 3T3-L1 adipocytes. Together with previous results, these data support a model whereby insulin stimulates TUG cleavage to liberate GLUT4 storage vesicles from the Golgi matrix, which promotes GLUT4 translocation to the cell surface and enhances glucose uptake.
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Affiliation(s)
- Jonathan S Bogan
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520-8020, USA.
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27
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The Golgi-associated long coiled-coil protein NECC1 participates in the control of the regulated secretory pathway in PC12 cells. Biochem J 2012; 443:387-96. [PMID: 22250954 DOI: 10.1042/bj20110554] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Golgi-associated long coiled-coil proteins, often referred to as golgins, are involved in the maintenance of the structural organization of the Golgi apparatus and the regulation of membrane traffic events occurring in this organelle. Little information is available on the contribution of golgins to Golgi function in cells specialized in secretion such as endocrine cells or neurons. In the present study, we characterize the intracellular distribution as well as the biochemical and functional properties of a novel long coiled-coil protein present in neuroendocrine tissues, NECC1 (neuroendocrine long coiled-coil protein 1). The present study shows that NECC1 is a peripheral membrane protein displaying high stability to detergent extraction, which distributes across the Golgi apparatus in neuroendocrine cells. In addition, NECC1 partially localizes to post-Golgi carriers containing secretory cargo in PC12 cells. Overexpression of NECC1 resulted in the formation of juxtanuclear aggregates together with a slight fragmentation of the Golgi and a decrease in K+-stimulated hormone release. In contrast, NECC1 silencing did not alter Golgi architecture, but enhanced K+-stimulated hormone secretion in PC12 cells. In all, the results of the present study identify NECC1 as a novel component of the Golgi matrix and support a role for this protein as a negative modulator of the regulated trafficking of secretory cargo in neuroendocrine cells.
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28
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Abstract
To enhance glucose uptake into muscle and fat cells, insulin stimulates the translocation of GLUT4 glucose transporters from intracellular membranes to the cell surface. This response requires the intersection of insulin signaling and vesicle trafficking pathways, and it is compromised in the setting of overnutrition to cause insulin resistance. Insulin signals through AS160/Tbc1D4 and Tbc1D1 to modulate Rab GTPases and through the Rho GTPase TC10α to act on other targets. In unstimulated cells, GLUT4 is incorporated into specialized storage vesicles containing IRAP, LRP1, sortilin, and VAMP2, which are sequestered by TUG, Ubc9, and other proteins. Insulin mobilizes these vesicles directly to the plasma membrane, and it modulates the trafficking itinerary so that cargo recycles from endosomes during ongoing insulin exposure. Knowledge of how signaling and trafficking pathways are coordinated will be essential to understanding the pathogenesis of diabetes and the metabolic syndrome and may also inform a wide range of other physiologies.
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Affiliation(s)
- Jonathan S Bogan
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520-8020, USA.
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29
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Orme CM, Bogan JS. The ubiquitin regulatory X (UBX) domain-containing protein TUG regulates the p97 ATPase and resides at the endoplasmic reticulum-golgi intermediate compartment. J Biol Chem 2011; 287:6679-92. [PMID: 22207755 DOI: 10.1074/jbc.m111.284232] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
p97/VCP is a hexameric ATPase that is coupled to diverse cellular processes, such as membrane fusion and proteolysis. How p97 activity is regulated is not fully understood. Here we studied the potential role of TUG, a widely expressed protein containing a UBX domain, to control mammalian p97. In HEK293 cells, the vast majority of TUG was bound to p97. Surprisingly, the TUG UBX domain was neither necessary nor sufficient for this interaction. Rather, an extended sequence, comprising three regions of TUG, bound to the p97 N-terminal domain. The TUG C terminus resembled the Arabidopsis protein PUX1. Similar to the previously described action of PUX1 on AtCDC48, TUG caused the conversion of p97 hexamers into monomers. Hexamer disassembly was stoichiometric rather than catalytic and was not greatly affected by the p97 ATP-binding state or by TUG N-terminal regions in vitro. In HeLa cells, TUG localized to the endoplasmic reticulum-to-Golgi intermediate compartment and endoplasmic reticulum exit sites. Although siRNA-mediated TUG depletion had no marked effect on total ubiquitylated proteins or p97 localization, TUG overexpression caused an accumulation of ubiquitylated substrates and targeted both TUG and p97 to the nucleus. A physiologic role of TUG was revealed by siRNA-mediated depletion, which showed that TUG is required for efficient reassembly of the Golgi complex after brefeldin A removal. Together, these data support a model in which TUG controls p97 oligomeric status at a particular location in the early secretory pathway and in which this process regulates membrane trafficking in various cell types.
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Affiliation(s)
- Charisse M Orme
- Section of Endocrinology and Metabolism, Department of Internal Medicine, University School of Medicine, New Haven, Connecticut 06520-8020, USA
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30
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Hatakeyama H, Kanzaki M. Molecular basis of insulin-responsive GLUT4 trafficking systems revealed by single molecule imaging. Traffic 2011; 12:1805-20. [PMID: 21910807 DOI: 10.1111/j.1600-0854.2011.01279.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Development of a 'static retention' property of GLUT4, the insulin-responsive glucose transporter, has emerged as being essential for achieving its maximal insulin-induced surface exposure. Herein, employing quantum-dot-based nanometrology of intracellular GLUT4 behavior, we reveal the molecular basis of its systematization endowed upon adipogenic differentiation of 3T3L1 cells. Specifically, (i) the endosomes-to-trans-Golgi network (TGN) retrieval system specialized for GLUT4 develops in response to sortilin expression, which requires an intricately balanced interplay among retromers, golgin-97 and syntaxin-6, the housekeeping vesicle trafficking machinery. (ii) The Golgin-97-localizing subdomain of the differentiated TGN apparently serves as an intermediate transit route by which GLUT4 can further proceed to the stationary GLUT4 storage compartment. (iii) AS160/Tbc1d4 then renders the 'static retention' property insulin responsive, i.e. insulin liberates GLUT4 from the static state only in the presence of functional AS160/Tbc1d4. (iv) Moreover, sortilin malfunction and the resulting GLUT4 sorting defects along with retarded TGN function might be etiologically related to insulin resistance. Together, these observations provide a conceptual framework for understanding maturation/retardation of the insulin-responsive GLUT4 trafficking system that relies on the specialized subdomain of differentiated TGN.
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Affiliation(s)
- Hiroyasu Hatakeyama
- Graduate School of Biomedical Engineering, Tohoku University, Sendai, Miyagi 980-8575, Japan
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31
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Berenguer M, Zhang J, Bruce MC, Martinez L, Gonzalez T, Gurtovenko AA, Xu T, Le Marchand-Brustel Y, Govers R. Dimethyl sulfoxide enhances GLUT4 translocation through a reduction in GLUT4 endocytosis in insulin-stimulated 3T3-L1 adipocytes. Biochimie 2011; 93:697-709. [DOI: 10.1016/j.biochi.2010.12.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Accepted: 12/21/2010] [Indexed: 01/14/2023]
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32
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Foley K, Boguslavsky S, Klip A. Endocytosis, recycling, and regulated exocytosis of glucose transporter 4. Biochemistry 2011; 50:3048-61. [PMID: 21405107 DOI: 10.1021/bi2000356] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Glucose transporter 4 (GLUT4) is responsible for the uptake of glucose into muscle and adipose tissues. Under resting conditions, GLUT4 is dynamically retained through idle cycling among selective intracellular compartments, from whence it undergoes slow recycling to the plasma membrane (PM). This dynamic retention can be released by command from intracellular signals elicited by insulin and other stimuli, which result in 2-10-fold increases in the surface level of GLUT4. Insulin-derived signals promote translocation of GLUT4 to the PM from a specialized compartment termed GLUT4 storage vesicles (GSV). Much effort has been devoted to the characterization of the intracellular compartments and dynamics of GLUT4 cycling and to the signals by which GLUT4 is sorted into, and recruited from, GSV. This review summarizes our understanding of intracellular GLUT4 traffic during its internalization from the membrane, its slow, constitutive recycling, and its regulated exocytosis in response to insulin. In spite of specific differences in GLUT4 dynamic behavior in adipose and muscle cells, the generalities of its endocytic and exocytic itineraries are consistent and an array of regulatory proteins that regulate each vesicular traffic event emerges from these cell systems.
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Affiliation(s)
- Kevin Foley
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario M4G 1X8, Canada
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33
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Abstract
Translocation of Glut4 to the plasma membrane of fat and skeletal muscle cells is mediated by specialized insulin-responsive vesicles (IRVs), whose protein composition consists primarily of glucose transporter isoform 4 (Glut4), insulin-responsive amino peptidase (IRAP), sortilin, lipoprotein receptor-related protein 1 (LRP1) and v-SNAREs. How can these proteins find each other in the cell and form functional vesicles after endocytosis from the plasma membrane? We are proposing a model according to which the IRV component proteins are internalized into sorting endosomes and are delivered to the IRV donor compartment(s), recycling endosomes and/or the trans-Golgi network (TGN), by cellugyrin-positive transport vesicles. The cytoplasmic tails of Glut4, IRAP, LRP1 and sortilin play an important targeting role in this process. Once these proteins arrive in the donor compartment, they interact with each other via their lumenal domains. This facilitates clustering of the IRV proteins into an oligomeric complex, which can then be distributed from the donor membranes to the IRV as a single entity with the help of adaptors, such as Golgi-localized, gamma-adaptin ear-containing, ARF-binding (GGA).
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Affiliation(s)
- Konstantin V Kandror
- Department of Biochemistry, Boston University School of Medicine, 72 E. Concord Street, Boston, MA 02118, USA
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34
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Berenguer M, Martinez L, Giorgetti-Peraldi S, Le Marchand-Brustel Y, Govers R. A serum factor induces insulin-independent translocation of GLUT4 to the cell surface which is maintained in insulin resistance. PLoS One 2010; 5:e15560. [PMID: 21187969 PMCID: PMC3004919 DOI: 10.1371/journal.pone.0015560] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Accepted: 11/12/2010] [Indexed: 01/24/2023] Open
Abstract
In response to insulin, glucose transporter GLUT4 translocates from intracellular compartments towards the plasma membrane where it enhances cellular glucose uptake. Here, we show that sera from various species contain a factor that dose-dependently induces GLUT4 translocation and glucose uptake in 3T3-L1 adipocytes, human adipocytes, myoblasts and myotubes. Notably, the effect of this factor on GLUT4 is fully maintained in insulin-resistant cells. Our studies demonstrate that the serum-induced increase in cell surface GLUT4 levels is not due to inhibition of its internalization and is not mediated by insulin, PDGF, IGF-1, or HGF. Similarly to insulin, serum also augments cell surface levels of GLUT1 and TfR. Remarkably, the acute effect of serum on GLUT4 is largely additive to that of insulin, while it also sensitizes the cells to insulin. In accordance with these findings, serum does not appear to activate the same repertoire of downstream signaling molecules that are implicated in insulin-induced GLUT4 translocation. We conclude that in addition to insulin, at least one other biological proteinaceous factor exists that contributes to GLUT4 regulation and still functions in insulin resistance. The challenge now is to identify this factor.
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Affiliation(s)
- Marion Berenguer
- INSERM, U895, Mediterranean Research Center for Molecular Medicine (C3M), Avenir Team 9, Nice, France
- University of Nice-Sophia-Antipolis, Faculty of Medicine, Signaling and pathologies (IFR50), Nice, France
| | - Laurène Martinez
- INSERM, U895, Mediterranean Research Center for Molecular Medicine (C3M), Avenir Team 9, Nice, France
- University of Nice-Sophia-Antipolis, Faculty of Medicine, Signaling and pathologies (IFR50), Nice, France
| | - Sophie Giorgetti-Peraldi
- INSERM, U895, Mediterranean Research Center for Molecular Medicine (C3M), Team 7, Nice, France
- University of Nice-Sophia-Antipolis, Faculty of Medicine, Signaling and pathologies (IFR50), Nice, France
| | - Yannick Le Marchand-Brustel
- INSERM, U895, Mediterranean Research Center for Molecular Medicine (C3M), Avenir Team 9, Nice, France
- INSERM, U895, Mediterranean Research Center for Molecular Medicine (C3M), Team 7, Nice, France
- University of Nice-Sophia-Antipolis, Faculty of Medicine, Signaling and pathologies (IFR50), Nice, France
| | - Roland Govers
- INSERM, U895, Mediterranean Research Center for Molecular Medicine (C3M), Avenir Team 9, Nice, France
- University of Nice-Sophia-Antipolis, Faculty of Medicine, Signaling and pathologies (IFR50), Nice, France
- * E-mail:
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35
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TGN golgins, Rabs and cytoskeleton: regulating the Golgi trafficking highways. Trends Cell Biol 2010; 20:329-36. [DOI: 10.1016/j.tcb.2010.02.006] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2009] [Revised: 02/15/2010] [Accepted: 02/17/2010] [Indexed: 12/22/2022]
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36
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Altered GLUT4 trafficking in adipocytes in the absence of the GTPase Arfrp1. Biochem Biophys Res Commun 2010; 394:896-903. [PMID: 20230794 DOI: 10.1016/j.bbrc.2010.03.059] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Accepted: 03/10/2010] [Indexed: 12/16/2022]
Abstract
The GTPase ADP-ribosylation factor related protein 1 (ARFRP1) controls the recruitment of proteins such as golgin-245 to the trans-Golgi. ARFRP1 is highly expressed in adipose tissues in which the insulin-sensitive glucose transporter GLUT4 is processed through the Golgi to a specialized endosomal compartment, the insulin-responsive storage compartment from which it is translocated to the plasma membrane in response to a stimulation of cells by insulin. In order to examine the role of ARFRP1 for GLUT4 targeting, subcellular distribution of GLUT4 was investigated in adipose tissue specific Arfrp1 knockout (Arfrp1(ad)(-/-)) mice. Immunohistochemical and ultrastructural studies of brown adipocytes demonstrated an abnormal trans-Golgi in Arfrp1(ad)(-/-) adipocytes. In addition, in Arfrp1(ad)(-/-) adipocytes GLUT4 protein accumulated at the plasma membrane rather than being sequestered in an intracellular compartment. A similar missorting of GLUT4 was produced by siRNA-mediated knockdown of Arfrp1 in 3T3-L1 adipocytes which was associated with significantly elevated uptake of deoxyglucose under basal conditions. Thus, Arfrp1 appears to be involved in sorting of GLUT4.
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37
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Capilla E, Díaz M, Hou JC, Planas JV, Pessin JE. High basal cell surface levels of fish GLUT4 are related to reduced sensitivity of insulin-induced translocation toward GGA and AS160 inhibition in adipocytes. Am J Physiol Endocrinol Metab 2010; 298:E329-36. [PMID: 20075431 PMCID: PMC2822488 DOI: 10.1152/ajpendo.00547.2009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Glucose entry into cells is mediated by a family of facilitative transporter proteins (GLUTs). In mammals, GLUT4 is expressed in insulin-sensitive tissues and is responsible for the postprandial uptake of glucose. In fish, GLUT4 also mediates insulin-regulated glucose entry into cells but differs from mammalian GLUT4 in its affinity for glucose and in protein motifs known to be important for the traffic of GLUT4. In this study, we have characterized the intracellular and plasma membrane (PM) traffic of two orthologs of GLUT4 in fish, trout (btGLUT4) and salmon (okGLUT4), that do not share the amino terminal FQQI targeting motif of mammalian GLUT4. btGLUT4 (FQHL) and, to a lesser extent, okGLUT4 (FQQL) showed higher basal PM levels, faster traffic to the PM after biosynthesis, and earlier acquisition of insulin responsiveness than rat GLUT4. Furthermore, btGLUT4 showed a similar profile of internalization than rat GLUT4. Expression of the dominant-interfering AS160-4P mutant caused a significant decrease in the insulin-induced PM levels of okGLUT4 and rat GLUT4 and, to a lesser extent, of btGLUT4, suggesting that btGLUT4 has reduced retention into the IRC. Contrary to rat GLUT4 and okGLUT4, the presence of btGLUT4 at the PM under insulin-stimulated conditions was not affected by coexpression of a dominant-interfering GGA mutant. These data suggest that fish GLUT4 follow a different trafficking pathway to the PM compared with rat GLUT4 that seems to be relatively independent of GGA. These results indicate that the regulated trafficking characteristics of GLUT4 have been modified during evolution from fish to mammals.
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Affiliation(s)
- Encarnación Capilla
- Departament de Fisiologia, Facultat de Biologia, Universitat de Barcelona and Institut de Biomedicina de la Universitat de Barcelona, Barcelona, Spain
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38
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Martinez L, Berenguer M, Bruce MC, Le Marchand-Brustel Y, Govers R. Rosiglitazone increases cell surface GLUT4 levels in 3T3-L1 adipocytes through an enhancement of endosomal recycling. Biochem Pharmacol 2009; 79:1300-9. [PMID: 20026082 DOI: 10.1016/j.bcp.2009.12.013] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2009] [Revised: 12/06/2009] [Accepted: 12/10/2009] [Indexed: 10/20/2022]
Abstract
Insulin induces a translocation of the glucose transporter GLUT4 from intracellular storage compartments towards the cell surface in adipocytes and skeletal muscle cells, allowing the cells to take up glucose. In type 2 diabetes-associated insulin resistance, the efficiency of this process is reduced. The thiazolidinediones, widely prescribed as anti-diabetic therapy, are generally regarded as insulin-sensitizers. The aim of this study was to evaluate the effect of the thiazolidinedione rosiglitazone (BRL 49653) on GLUT4 in adipocytes. When applied during differentiation, rosiglitazone dose dependently augmented GLUT4 expression along with the formation of lipid droplets. Intriguingly, its presence during differentiation led to increases in both cell surface GLUT4 levels and insulin sensitivity of GLUT4 translocation in mature adipocytes. Treatment of fully differentiated adipocytes with rosiglitazone also led to increases in GLUT4 at the plasma membrane. Rosiglitazone similarly affected cell surface levels of the endosomal transferrin receptor, but did not alter the GLUT4 internalization rate. The augmentation in cell surface GLUT4 levels was maintained in adipocytes that were rendered insulin-resistant in vitro by a 24h insulin treatment and moreover in these cells rosiglitazone also fully restored insulin-induced GLUT4 translocation. We conclude that in adipocytes, rosiglitazone increases cell surface GLUT4 levels by increasing its endosomal recycling and restores insulin-induced GLUT4 translocation in insulin resistance. These results implicate novel modes of action on GLUT4 that are all likely to contribute to the insulin-sensitizing effect of rosiglitazone in type 2 diabetes.
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Affiliation(s)
- Laurène Martinez
- Inserm U895, Mediterranean Research Center for Molecular Medicine (C3M), Avenir Team 9, Nice F-06204, France
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39
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Golgins and GRASPs: holding the Golgi together. Semin Cell Dev Biol 2009; 20:770-9. [PMID: 19508854 DOI: 10.1016/j.semcdb.2009.03.011] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2009] [Revised: 03/16/2009] [Accepted: 03/17/2009] [Indexed: 12/28/2022]
Abstract
The GRASP and golgin families of proteins have emerged as key components of the Golgi apparatus, with major roles in both the structural organisation of this organelle and the trafficking that occurs there. Both types of protein participate in membrane tethering events that occur upstream of membrane fusion as well as contributing to the structural scaffold that defines Golgi architecture, referred to as the Golgi matrix. The importance of these proteins is highlighted by their targeting in mitosis, apoptosis, and pathogenic infections that cause dramatic structural and functional reorganisation of the Golgi apparatus. In this review we will discuss our current understanding of GRASP and golgin function, highlighting some of the common themes that have emerged as well as describing previously unsuspected roles for these proteins in various cellular processes.
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40
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Sztul E, Lupashin V. Role of vesicle tethering factors in the ER-Golgi membrane traffic. FEBS Lett 2009; 583:3770-83. [PMID: 19887069 DOI: 10.1016/j.febslet.2009.10.083] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Revised: 10/29/2009] [Accepted: 10/30/2009] [Indexed: 12/27/2022]
Abstract
Tethers are a diverse group of loosely related proteins and protein complexes grouped into three families based on structural and functional similarities. A well-accepted role for tethering factors is the initial attachment of transport carriers to acceptor membranes prior to fusion. However, accumulating evidence indicates that tethers are more than static bridges. Tethers have been shown to interact with components of the fusion machinery and with components involved in vesicle formation. Tethers belonging to the three families act at the same stage of traffic, suggesting that they mediate distinct events during vesicle tethering. Thus, multiple tether-facilitated events are required to provide selectivity to vesicle fusion. In this review, we highlight findings that support this model.
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Affiliation(s)
- Elizabeth Sztul
- Department of Cell Biology, University of Alabama at Birmingham, 1918 University Boulevard, Birmingham, AL 35294, USA
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41
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Yadav S, Puri S, Linstedt AD. A primary role for Golgi positioning in directed secretion, cell polarity, and wound healing. Mol Biol Cell 2009; 20:1728-36. [PMID: 19158377 DOI: 10.1091/mbc.e08-10-1077] [Citation(s) in RCA: 236] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Peri-centrosomal positioning of the mammalian Golgi apparatus is known to involve microtubule-based motility, but its importance for cellular physiology is a major unanswered question. Here, we identify golgin-160 and GMAP210 as proteins required for centripetal motility of Golgi membranes. In the absence of either golgin, peri-centrosomal positioning of the Golgi apparatus was disrupted while the cytoskeleton remained intact. Although secretion persisted with normal kinetics, it was evenly distributed in response to wounding rather than directed to the wound edge. Strikingly, these cells also completely failed to polarize. Further, directionally persistent cell migration was inhibited such that wound closure was impaired. These findings not only reveal novel roles for golgin-160 and GMAP210 in conferring membrane motility but also indicate that Golgi positioning has an active role in directed secretion, cell polarity, and wound healing.
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Affiliation(s)
- Smita Yadav
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
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42
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Rubin BR, Bogan JS. Intracellular retention and insulin-stimulated mobilization of GLUT4 glucose transporters. VITAMINS AND HORMONES 2009; 80:155-92. [PMID: 19251038 DOI: 10.1016/s0083-6729(08)00607-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
GLUT4 glucose transporters are expressed nearly exclusively in adipose and muscle cells, where they cycle to and from the plasma membrane. In cells not stimulated with insulin, GLUT4 is targeted to specialized GLUT4 storage vesicles (GSVs), which sequester it away from the cell surface. Insulin acts within minutes to mobilize these vesicles, translocating GLUT4 to the plasma membrane to enhance glucose uptake. The mechanisms controlling GSV sequestration and mobilization are poorly understood. An insulin-regulated aminopeptidase that cotraffics with GLUT4, IRAP, is required for basal GSV retention and insulin-stimulated mobilization. TUG and Ubc9 bind GLUT4, and likely retain GSVs within unstimulated cells. These proteins may be components of a retention receptor, which sequesters GLUT4 and IRAP away from recycling vesicles. Insulin may then act on this protein complex to liberate GLUT4 and IRAP, discharging GSVs into a recycling pathway for fusion at the cell surface. How GSVs are anchored intracellularly, and how insulin mobilizes these vesicles, are the important topics for ongoing research. Regulation of GLUT4 trafficking is tissue-specific, perhaps in part because the formation of GSVs requires cell type-specific expression of sortilin. Proteins controlling GSV retention and mobilization can then be more widely expressed. Indeed, GLUT4 likely participates in a general mechanism by which the cell surface delivery of various membrane proteins can be controlled by extracellular stimuli. Finally, it is not known if defects in the formation or intracellular retention of GSVs contribute to human insulin resistance, or play a role in the pathogenesis of type 2 diabetes.
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Affiliation(s)
- Bradley R Rubin
- Department of Internal Medicine, Yale School of Medicine, New Haven, CT 06520-8020, USA
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43
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Pilch PF. The mass action hypothesis: formation of Glut4 storage vesicles, a tissue-specific, regulated exocytic compartment. Acta Physiol (Oxf) 2008; 192:89-101. [PMID: 18171432 DOI: 10.1111/j.1748-1716.2007.01788.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Insulin stimulates glucose uptake into the target tissues of fat and muscle by recruiting or translocating Glut4 glucose transport proteins to their functional location at the cell surface. In the basal state, Glut4 is sequestered intracellularly in several vesicular compartments, one of which has come to be known as Glut4 storage vesicles (GSVs). The GSVs represent a tissue-specific compartment that is an ultimate target of the insulin signalling cascade. Glut4 translocation has been extensively studied because of its intrinsic scientific importance to cell biology as well as its relevance to the pathology of type 2 diabetes mellitus. I review herein the ontogeny of GSVs and their composition as it relates to a tissue-specific, hormone-sensitive exocytic compartment and propose a mechanism for their formation.
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Affiliation(s)
- P F Pilch
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA.
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Díaz M, Antonescu CN, Capilla E, Klip A, Planas JV. Fish glucose transporter (GLUT)-4 differs from rat GLUT4 in its traffic characteristics but can translocate to the cell surface in response to insulin in skeletal muscle cells. Endocrinology 2007; 148:5248-57. [PMID: 17702851 DOI: 10.1210/en.2007-0265] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In mammals, glucose transporter (GLUT)-4 plays an important role in glucose homeostasis mediating insulin action to increase glucose uptake in insulin-responsive tissues. In the basal state, GLUT4 is located in intracellular compartments and upon insulin stimulation is recruited to the plasma membrane, allowing glucose entry into the cell. Compared with mammals, fish are less efficient restoring plasma glucose after dietary or exogenous glucose administration. Recently our group cloned a GLUT4-homolog in skeletal muscle from brown trout (btGLUT4) that differs in protein motifs believed to be important for endocytosis and sorting of mammalian GLUT4. To study the traffic of btGLUT4, we generated a stable L6 muscle cell line overexpressing myc-tagged btGLUT4 (btGLUT4myc). Insulin stimulated btGLUT4myc recruitment to the cell surface, although to a lesser extent than rat-GLUT4myc, and enhanced glucose uptake. Interestingly, btGLUT4myc showed a higher steady-state level at the cell surface under basal conditions than rat-GLUT4myc due to a higher rate of recycling of btGLUT4myc and not to a slower endocytic rate, compared with rat-GLUT4myc. Furthermore, unlike rat-GLUT4myc, btGLUT4myc had a diffuse distribution throughout the cytoplasm of L6 myoblasts. In primary brown trout skeletal muscle cells, insulin also promoted the translocation of endogenous btGLUT4 to the plasma membrane and enhanced glucose transport. Moreover, btGLUT4 exhibited a diffuse intracellular localization in unstimulated trout myocytes. Our data suggest that btGLUT4 is subjected to a different intracellular traffic from rat-GLUT4 and may explain the relative glucose intolerance observed in fish.
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Affiliation(s)
- Mònica Díaz
- Departament de Fisiologia, Facultat de Biologia, Universitat de Barcelona, 08028, Barcelona, Spain
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Abstract
Despite being one of the first recognized targets of insulin action, the acceleration of glucose transport into muscle and fat tissue remains one of the most enigmatic processes in the insulin action cascade. Glucose transport is accomplished by a shift in the distribution of the insulin-responsive glucose transporter GLUT4 from intracellular compartments to the plasma membrane in the presence of insulin. The complexity in deciphering the molecular blueprint of insulin regulation of glucose transport arises because it represents a convergence of two convoluted biological systems-vesicular transport and signal transduction. Whereas more than 60 molecular players have been implicated in this orchestral performance, it has been difficult to distinguish between mainly passive participants vs. those that are clearly driving the process. The maze-like nature of the endosomal system makes it almost impossible to dissect the anatomical nature of what appears to be a medley of many overlapping and rapidly changing transitions. A major limitation is technology. It is clear that further progress in teasing apart the GLUT4 code will require the development and application of novel and advanced technologies that can discriminate one molecule from another in the living cell and to superimpose this upon a system in which the molecular environment can be carefully manipulated. Many are now taking on this challenge.
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Affiliation(s)
- Mark Larance
- Diabetes and Obesity Research Program, Garvan Institute of Medical Research, Sydney 2010, Australia
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46
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Sbodio JI, Machamer CE. Identification of a redox-sensitive cysteine in GCP60 that regulates its interaction with golgin-160. J Biol Chem 2007; 282:29874-81. [PMID: 17711851 DOI: 10.1074/jbc.m705794200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Golgin-160 is ubiquitously expressed in vertebrates. It localizes to the cytoplasmic side of the Golgi and has a large C-terminal coiled-coil domain. The noncoiled-coil N-terminal head domain contains Golgi targeting information, a cryptic nuclear localization signal, and three caspase cleavage sites. Caspase cleavage of the golgin-160 head domain generates different fragments that can translocate to the nucleus by exposing the nuclear localization signal. We have previously shown that GCP60, a Golgi resident protein, interacts weakly with the golgin-160 head domain but has a strong interaction with one of the caspase-generated golgin-160 fragments (residues 140-311). This preferential interaction increases the Golgi retention of the golgin-160 fragment in cells overexpressing GCP60. Here we studied the interaction of golgin-160-(140-311) with GCP60 and identified a single cysteine residue in GCP60 (Cys-463) that is critical for the interaction of the two proteins. Mutation of the cysteine blocked the interaction in vitro and disrupted the ability to retain the golgin-160 fragment at the Golgi in cells. We also found that Cys-463 is redox-sensitive; in its reduced form, interaction with golgin-160 was diminished or abolished, whereas oxidation of the Cys-463 by hydrogen peroxide restored the interaction. In addition, incubation with a nitric oxide donor promoted this interaction in vitro. These findings suggest that nuclear translocation of golgin-160-(140-311) is a highly coordinated event regulated not only by cleavage of the golgin-160 head but also by the oxidation state of GCP60.
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Affiliation(s)
- Juan I Sbodio
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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Abstract
Few physiological parameters are more tightly and acutely regulated in humans than blood glucose concentration. The major cellular mechanism that diminishes blood glucose when carbohydrates are ingested is insulin-stimulated glucose transport into skeletal muscle. Skeletal muscle both stores glucose as glycogen and oxidizes it to produce energy following the transport step. The principal glucose transporter protein that mediates this uptake is GLUT4, which plays a key role in regulating whole body glucose homeostasis. This review focuses on recent advances on the biology of GLUT4.
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Affiliation(s)
- Shaohui Huang
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
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Muretta JM, Romenskaia I, Cassiday PA, Mastick CC. Expression of a synapsin IIb site 1 phosphorylation mutant in 3T3-L1 adipocytes inhibits basal intracellular retention of Glut4. J Cell Sci 2007; 120:1168-77. [PMID: 17341582 DOI: 10.1242/jcs.03413] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Glut4 exocytosis in adipocytes uses protein machinery that is shared with other regulated secretory processes. Synapsins are phosphoproteins that regulate a ;reserve pool' of vesicles clustered behind the active zone in neurons. We found that adipocytes (primary cells and the 3T3-L1 cell line) express synapsin IIb mRNA and protein. Synapsin IIb co-localizes with Glut4 in perinuclear vesicle clusters. To test whether synapsin plays a role in Glut4 traffic, a site 1 phosphorylation mutant (S10A synapsin) was expressed in 3T3-L1 adipocytes. Interestingly, expression of S10A synapsin increased basal cell surface Glut4 almost fourfold (50% maximal insulin effect). Insulin caused a further twofold translocation of Glut4 in these cells. Expression of the N-terminus of S10A synapsin (amino acids 1-118) was sufficient to inhibit basal Glut4 retention. Neither wild-type nor S10D synapsin redistributed Glut4. S10A synapsin did not elevate surface levels of the transferrin receptor in adipocytes or Glut4 in fibroblasts. Therefore, S10A synapsin is inhibiting the specialized process of basal intracellular retention of Glut4 in adipocytes, without affecting general endocytic cycling. While mutant forms of many proteins inhibit Glut4 exocytosis in response to insulin, S10A synapsin is one of only a few that specifically inhibits Glut4 retention in basal adipocytes. These data indicate that the synapsins are important regulators of membrane traffic in many cell types.
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Affiliation(s)
- Joseph M Muretta
- Department of Biochemistry and Molecular Biology, Mailstop 330, University of Nevada, Reno, NV 89557, USA
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Yu C, Cresswell J, Löffler MG, Bogan JS. The glucose transporter 4-regulating protein TUG is essential for highly insulin-responsive glucose uptake in 3T3-L1 adipocytes. J Biol Chem 2007; 282:7710-22. [PMID: 17202135 PMCID: PMC2243252 DOI: 10.1074/jbc.m610824200] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Insulin stimulates glucose uptake in fat and muscle by redistributing GLUT4 glucose transporters from intracellular membranes to the cell surface. We previously proposed that, in 3T3-L1 adipocytes, TUG retains GLUT4 within unstimulated cells and insulin mobilizes this retained GLUT4 by stimulating its dissociation from TUG. Yet the relative importance of this action in the overall control of glucose uptake remains uncertain. Here we report that transient, small interfering RNA-mediated depletion of TUG causes GLUT4 translocation and enhances glucose uptake in unstimulated 3T3-L1 adipocytes, similar to insulin. Stable TUG depletion or expression of a dominant negative fragment likewise stimulates GLUT4 redistribution and glucose uptake, and insulin causes a 2-fold further increase. Microscopy shows that TUG governs the accumulation of GLUT4 in perinuclear membranes distinct from endosomes and indicates that it is this pool of GLUT4 that is mobilized by TUG disruption. Interestingly, in addition to translocating GLUT4 and enhancing glucose uptake, TUG disruption appears to accelerate the degradation of GLUT4 in lysosomes. Finally, we find that TUG binds directly and specifically to a large intracellular loop in GLUT4. Together, these findings demonstrate that TUG is required to retain GLUT4 intracellularly in 3T3-L1 adipocytes in the absence of insulin and further implicate the insulin-stimulated dissociation of TUG and GLUT4 as an important action by which insulin stimulates glucose uptake.
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Affiliation(s)
- Chenfei Yu
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520
| | - James Cresswell
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520
| | - Michael G. Löffler
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520
| | - Jonathan S. Bogan
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520
- ¶Address correspondence to: Jonathan S. Bogan, Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, 333 Cedar St., P.O. Box 208020, New Haven, CT 06520-8020, Tel. (203) 785-6319; Fax. (203) 785-6462; E-Mail:
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Hicks SW, Horn TA, McCaffery JM, Zuckerman DM, Machamer CE. Golgin-160 Promotes Cell Surface Expression of the Beta-1 Adrenergic Receptor. Traffic 2006; 7:1666-77. [PMID: 17118120 DOI: 10.1111/j.1600-0854.2006.00504.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Golgin-160 is a ubiquitously expressed peripheral Golgi membrane protein that is important for transduction of certain pro-apoptotic signals at the Golgi complex. However, the role of golgin-160 in normal Golgi structure and function is unknown. Here, we show that depletion of golgin-160 using RNA interference (RNAi) does not affect Golgi morphology or constitutive membrane traffic in HeLa cells. However, depletion of golgin-160 leads to significantly decreased cell surface levels of exogenously expressed beta1-adrenergic receptor (beta1AR), which can be rescued by expression of RNAi-resistant forms of golgin-160. Furthermore, overexpression of golgin-160 leads to higher surface levels of beta1AR. Golgin-160 is localized mostly in the cis and medial regions of the Golgi stack by immunoelectron microscopy, suggesting that it does not directly promote incorporation of beta1AR into transport vesicles at the trans Golgi network. Golgin-160 interacts with beta1AR in vitro, and we mapped the interaction to a region between residues 140 and 257 in the head of golgin-160 and the third intracellular loop of beta1AR. Our results support the idea that golgin-160 may promote efficient surface delivery of a subset of cargo molecules.
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Affiliation(s)
- Stuart W Hicks
- Department of Cell Biology, Johns Hopkins University School of Medicine, 725 Wolfe Street, Baltimore, MD 21205, USA
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