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J Biol Chem. 2015 Feb 13;290(7):4447-63. doi: 10.1074/jbc.M114.603977. Epub 2015 Jan 5.

Acetylation of TUG protein promotes the accumulation of GLUT4 glucose transporters in an insulin-responsive intracellular compartment.

Author information

1
From the Section of Endocrinology and Metabolism, Department of Internal Medicine, Department of Cell Biology.
2
From the Section of Endocrinology and Metabolism, Department of Internal Medicine.
3
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.
4
From the Section of Endocrinology and Metabolism, Department of Internal Medicine, Department of Cell Biology, jonathan.bogan@yale.edu.

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.

KEYWORDS:

Adipocyte; Glucose Transport; Glucose Transporter Type 4 (GLUT4); Insulin; Membrane Trafficking; Nutrition; Protein Translocation; Sirtuin; Skeletal Muscle Metabolism

PMID:
25561724
PMCID:
PMC4326849
DOI:
10.1074/jbc.M114.603977
[Indexed for MEDLINE]
Free PMC Article

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