title: Acetylation of TUG protein promotes the accumulation of GLUT4 glucose transporters in an insulin-responsive intracellular compartment.
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.
authors.affiliation: From the Section of Endocrinology and Metabolism, Department of Internal Medicine, Department of Cell Biology.
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Belman
authors.affiliation: From the Section of Endocrinology and Metabolism, Department of Internal Medicine.
authors.forename: Rachel R
authors.initials: RR
authors.lastname: Bian
authors.affiliation: From the Section of Endocrinology and Metabolism, Department of Internal Medicine.
authors.forename: Estifanos N
authors.initials: EN
authors.lastname: Habtemichael
authors.affiliation: From the Section of Endocrinology and Metabolism, Department of Internal Medicine.
authors.forename: Don T
authors.initials: DT
authors.lastname: Li
authors.affiliation: From the Section of Endocrinology and Metabolism, Department of Internal Medicine.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Jurczak
authors.affiliation: From the Section of Endocrinology and Metabolism, Department of Internal Medicine.
authors.forename: Abel
authors.initials: A
authors.lastname: Alcázar-Román
authors.affiliation: From the Section of Endocrinology and Metabolism, Department of Internal Medicine.
authors.forename: Leah J
authors.initials: LJ
authors.lastname: McNally
authors.affiliation: 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.
authors.forename: Gerald I
authors.initials: GI
authors.lastname: Shulman
authors.affiliation: From the Section of Endocrinology and Metabolism, Department of Internal Medicine, Department of Cell Biology, jonathan.bogan@yale.edu.
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Bogan
mesh_terms: D041721:3T3-L1 Cells; D000107:Acetylation; D017667:Adipocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D002352:Carrier Proteins / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D010122:Cystinyl Aminopeptidase / Q000235:genetics / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D005434:Flow Cytometry; D005947:Glucose / Q000378:metabolism; D051275:Glucose Transporter Type 4 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D047468:Immunoprecipitation; D007328:Insulin / Q000494:pharmacology*; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D021381:Protein Transport; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D056565:Sirtuin 2 / Q000235:genetics / Q000378:metabolism*
chemical_list: C478539:Aspscr1 protein, mouse; D002352:Carrier Proteins; D051275:Glucose Transporter Type 4; D007004:Hypoglycemic Agents; D007328:Insulin; D047908:Intracellular Signaling Peptides and Proteins; D012333:RNA, Messenger; C495693:Slc2a4 protein, mouse; D010122:Cystinyl Aminopeptidase; C105964:leucyl-cystinyl aminopeptidase; C418743:Sirt2 protein, mouse; D056565:Sirtuin 2; D005947:Glucose
keywords: Adipocyte; Glucose Transport; Glucose Transporter Type 4 (GLUT4); Insulin; Membrane Trafficking; Nutrition; Protein Translocation; Sirtuin; Skeletal Muscle Metabolism