title: Insulin-stimulated translocation of the HepG2/erythrocyte-type glucose transporter expressed in 3T3-L1 adipocytes.
abstract: Insulin stimulates glucose transport into adipocytes, at least in part, via the translocation of intracellular transporters to the plasma membrane. The human HepG2-type transporter, which is not insulin-responsive in its native cell type, was expressed in 3T3-L1 adipocytes by infection with recombinant retrovirus harboring the HepG2 transporter cDNA in order to determine whether glucose transporter translocation in adipocytes is restricted to a distinct insulin-sensitive transporter species. The distributions of the endogenous murine and the HepG2 transporters were estimated by quantitative immunoblot analysis of subcellular fractions probed with either a monoclonal antibody that recognized only the human transporter or a polyclonal antibody that recognized both transporter species. In the basal state, the intracellular membrane fraction comprised approximately 50% of the total of each transporter type. Insulin decreased the content of both transporter species in the intracellular membranes by approximately 50% and increased the plasma membrane content of both species by approximately 1.5-2-fold. The similar insulin-mediated increase in the plasma membrane content of endogenous murine and HepG2 glucose transporters was verified by labeling of cell surface glycoproteins with [3H]NaBH4 followed by immunoprecipitation with glucose transporter antibodies. These data indicate that insulin-mediated translocation in 3T3-L1 adipocytes is not restricted to a tissue-specific insulin-responsive glucose transporter species and suggest that other tissue-specific factors regulate the translocation process.
authors.affiliation: Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03756.
authors.forename: G W
authors.initials: GW
authors.lastname: Gould
authors.forename: V
authors.initials: V
authors.lastname: Derechin
authors.forename: D E
authors.initials: DE
authors.lastname: James
authors.forename: K
authors.initials: K
authors.lastname: Tordjman
authors.forename: S
authors.initials: S
authors.lastname: Ahern
authors.forename: E M
authors.initials: EM
authors.lastname: Gibbs
authors.forename: G E
authors.initials: GE
authors.lastname: Lienhard
authors.forename: M
authors.initials: M
authors.lastname: Mueckler
mesh_terms: D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D006528:Carcinoma, Hepatocellular; D002454:Cell Differentiation; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D004912:Erythrocytes / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D008113:Liver Neoplasms; D051379:Mice; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D007328:Insulin; D009004:Monosaccharide Transport Proteins