Potential role of protein kinase B in glucose transporter 4 translocation in adipocytes.
Phosphatidylinositol 3-kinase (PI 3-kinase) activation promotes glucose transporter 4 (Glut 4) translocation in adipocytes. In this study, we demonstrate that protein kinase B, a serine/threonine kinase stimulated by PI 3-kinase, is activated by both insulin and okadaic acid in isolated adipocytes, in parallel with their effects on Glut 4 translocation. In 3T3-L1 adipocytes, platelet-derived growth factor activated PI 3-kinase as efficiently as insulin but was only half as potent as insulin in promoting protein kinase B (PKB) activation. To look for a potential role of PKB in Glut 4 translocation, adipocytes were transfected with a constitutively active PKB (Gag-PKB) together with an epitope tagged transporter (Glut 4 myc). Gag-PKB was associated with all membrane fractions, whereas the endogenous PKB was mostly cytosolic. Expression of Gag-PKB led to an increase in Glut 4 myc amount at the cell surface. Our results suggest that PKB could play a role in promoting Glut 4 appearance at the cell surface following exposure of adipocytes to insulin and okadaic acid stimulation.
Tanti
J F
JF
INSERM U 145, Faculté de Médecine, Nice, France. tanti@unice.fr
Grillo
S
S
Grémeaux
T
T
Coffer
P J
PJ
Van Obberghen
E
E
Le Marchand-Brustel
Y
Y
D017667:Adipocytes / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D004789:Enzyme Activation / Q000187:drug effects; D051275:Glucose Transporter Type 4; D015151:Immunoblotting; D007163:Immunosorbent Techniques; D007328:Insulin / Q000494:pharmacology; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D009124:Muscle Proteins; D019319:Okadaic Acid / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D017208:Rats, Wistar; D014162:Transfection
D051275:Glucose Transporter Type 4; D007328:Insulin; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D019319:Okadaic Acid; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D010982:Platelet-Derived Growth Factor; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; C495694:Slc2a4 protein, rat