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Habtemichael EN, Alcázar-Román A, Rubin BR, Grossi LR, Belman JP, Julca O, Löffler MG, Li H, Chi NW, Samuel VT, Bogan JS. Coordinated Regulation of Vasopressin Inactivation and Glucose Uptake by Action of TUG Protein in Muscle. J Biol Chem 2015; 290:14454-61. [PMID: 25944897 DOI: 10.1074/jbc.c115.639203] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Indexed: 01/16/2023] Open
Abstract
In adipose and muscle cells, insulin stimulates the exocytic translocation of vesicles containing GLUT4, a glucose transporter, and insulin-regulated aminopeptidase (IRAP), a transmembrane aminopeptidase. A substrate of IRAP is vasopressin, which controls water homeostasis. The physiological importance of IRAP translocation to inactivate vasopressin remains uncertain. We previously showed that in skeletal muscle, insulin stimulates proteolytic processing of the GLUT4 retention protein, TUG, to promote GLUT4 translocation and glucose uptake. Here we show that TUG proteolysis also controls IRAP targeting and regulates vasopressin action in vivo. Transgenic mice with constitutive TUG proteolysis in muscle consumed much more water than wild-type control mice. The transgenic mice lost more body weight during water restriction, and the abundance of renal AQP2 water channels was reduced, implying that vasopressin activity is decreased. To compensate for accelerated vasopressin degradation, vasopressin secretion was increased, as assessed by the cosecreted protein copeptin. IRAP abundance was increased in T-tubule fractions of fasting transgenic mice, when compared with controls. Recombinant IRAP bound to TUG, and this interaction was mapped to a short peptide in IRAP that was previously shown to be critical for GLUT4 intracellular retention. In cultured 3T3-L1 adipocytes, IRAP was present in TUG-bound membranes and was released by insulin stimulation. Together with previous results, these data support a model in which TUG controls vesicle translocation by interacting with IRAP as well as GLUT4. Furthermore, the effect of IRAP to reduce vasopressin activity is a physiologically important consequence of vesicle translocation, which is coordinated with the stimulation of glucose uptake.
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Affiliation(s)
| | - Abel Alcázar-Román
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine, and
| | - Bradley R Rubin
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine, and Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06520-8020
| | - Laura R Grossi
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine, and Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06520-8020
| | - Jonathan P Belman
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine, and Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06520-8020
| | - Omar Julca
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine, and Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06520-8020
| | - Michael G Löffler
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine, and
| | - Hongjie Li
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine, and
| | - Nai-Wen Chi
- the Veterans Affairs San Diego Healthcare System and Department of Medicine, University of California, San Diego, California 92093, and
| | - Varman T Samuel
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine, and the Veterans Affairs Medical Center, West Haven, Connecticut 06516
| | - Jonathan S Bogan
- From the Section of Endocrinology and Metabolism, Department of Internal Medicine, and Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06520-8020,
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Nagai Y, Yonemitsu S, Erion DM, Iwasaki T, Stark R, Weismann D, Dong J, Zhang D, Jurczak MJ, Löffler MG, Cresswell J, Yu XX, Murray SF, Bhanot S, Monia BP, Bogan JS, Samuel V, Shulman GI. The role of peroxisome proliferator-activated receptor gamma coactivator-1 beta in the pathogenesis of fructose-induced insulin resistance. Cell Metab 2009; 9:252-64. [PMID: 19254570 PMCID: PMC3131094 DOI: 10.1016/j.cmet.2009.01.011] [Citation(s) in RCA: 140] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2008] [Revised: 12/12/2008] [Accepted: 01/29/2009] [Indexed: 10/21/2022]
Abstract
Peroxisome proliferator-activated receptor gamma coactivator-1 beta (PGC-1beta) is known to be a transcriptional coactivator for SREBP-1, the master regulator of hepatic lipogenesis. Here, we evaluated the role of PGC-1beta in the pathogenesis of fructose-induced insulin resistance by using an antisense oligonucletoide (ASO) to knockdown PGC-1beta in liver and adipose tissue. PGC-1beta ASO improved the metabolic phenotype induced by fructose feeding by reducing expression of SREBP-1 and downstream lipogenic genes in liver. PGC-1beta ASO also reversed hepatic insulin resistance induced by fructose in both basal and insulin-stimulated states. Furthermore, PGC-1beta ASO increased insulin-stimulated whole-body glucose disposal due to a threefold increase in glucose uptake in white adipose tissue. These data support an important role for PGC-1beta in the pathogenesis of fructose-induced insulin resistance and suggest that PGC-1beta inhibition may be a therapeutic target for treatment of NAFLD, hypertriglyceridemia, and insulin resistance associated with increased de novo lipogenesis.
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Affiliation(s)
- Yoshio Nagai
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06536-8012, 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] [What about the content of this article? (0)] [Affiliation(s)] [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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