Insulin-stimulated translocation of the HepG2/erythrocyte-type glucose transporter expressed in 3T3-L1 adipocytes.
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.
Gould
G W
GW
Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03756.
Derechin
V
V
James
D E
DE
Tordjman
K
K
Ahern
S
S
Gibbs
E M
EM
Lienhard
G E
GE
Mueckler
M
M
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*
D007328:Insulin; D009004:Monosaccharide Transport Proteins