EXPRESSION OF A CONSTITUTIVELY ACTIVE AKT SER THR KINASE IN 3T3-L1 ADIPOCYTES STIMULATES GLUCOSE-UPTAKE AND GLUCOSE-TRANSPORTER-4 TRANSLOCATION/

Akt is a serine/threonine kinase that requires a functional phosphatid ylinositol 3-kinase to be stimulated by insulin and other growth facto rs. When directed to membranes by the addition of a are myristoylation sequence, Akt becomes constitutively active. In the present studies, the constitutively active Akt and a nonmyristoylated control mutant we re expressed in 3T3-L1 cells that can be induced to differentiate into adipocytes. The constitutively active Akt induced glucose uptake into adipocytes in the absence of insulin by stimulating translocation of the insulin-responsive glucose transporter 4 to the plasma membrane. T he constitutively active Akt also increased the synthesis of the ubiqu itously expressed glucose transporter 1. The increased glucose influx in the 3T3-L1 adipocytes directed Lipid but not glycogen synthesis. Th ese results indicate that Akt can regulate glucose uptake and metaboli sm.