The TC10-Interacting Protein CIP4/2 Is Required for Insulin-Stimulated Glut4 Translocation in 3T3L1 Adipocytes

The GTPase TC10 plays a critical role in insulin-stimulated glucose transport. We report here the identification of the TC10-interacting protein CIP4/2 (Cdc42-interacting protein 4/2) as an effector in this pathway. CIP4/2 localizes to an intracellular compartment under basal conditions and translocates to the plasma membrane on insulin stimulation. Overexpression of constitutively active TC10 brings CIP4/2 to the plasma membrane, whereas overexpression of an inhibitory form of TC10 blocks the translocation of CIP4/2 produced by insulin. Overexpression of mutant forms of CIP4/2 containing an N-terminal deletion or with diminished TC10 binding inhibits insulin-stimulated Glut4 translocation. These data suggest that CIP4/2 may play an important role in insulin-stimulated glucose transport as a downstream effector of TC10.