Analysis of insulin signalling by RNAi-based gene silencing. (26th October 2004)

• Record Type: Journal Article
• Authors: Zhou, Q.L.; Park, J.G.; Jiang, Z.Y.; Holik, J.J.; Mitra, P.; Semiz, S.; Guilherme, A.; Powelka, A.M.; Tang, X.; Virbasius, J.; Czech, M.P.
• Is Part Of: Biochemical Society transactions. Volume 32:Number 5(2004)
• Page Start: 817
• Page End: 821
• Publication Date: 2004-10-26
• Subjects: gene silencing -- glucose -- insulin signalling -- phosphoinositide 3-kinase (PI3K) -- phospholipase Cγ -- protein kinase Cλ/ζ siRNA; Biochemistry -- Congresses; 572
• DOI: 10.1042/BST0320817
• Languages: English
• ISSNs: 0300-5127

Abstract

Abstract : Using siRNA-mediated gene silencing in cultured adipocytes, we have dissected the insulin-signalling pathway leading to translocation of GLUT4 glucose transporters to the plasma membrane. RNAi (RNA interference)-based depletion of components in the putative TC10 pathway (CAP, CrkII and c-Cbl plus Cbl-b) or the phospholipase Cγ pathway failed to diminish insulin signalling to GLUT4. Within the phosphoinositide 3-kinase pathway, loss of the 5′-phosphatidylinositol 3, 4, 5-trisphosphate phosphatase SHIP2 was also without effect, whereas depletion of the 3′-phosphatase PTEN significantly enhanced insulin action. Downstream of phosphatidylinositol 3, 4, 5-trisphosphate and PDK1, silencing the genes encoding the protein kinases Akt1/PKBα, or CISK(SGK3) or protein kinases Cλ/ζ had little or no effect, but loss of Akt2/PKBβ significantly attenuated GLUT4 regulation by insulin. These results show that Akt2/PKBβ is the key downstream intermediate within the phosphoinositide 3-kinase pathway linked to insulin action on GLUT4 in cultured adipocytes, whereas PTEN is a potent negative regulator of this pathway.