Protein kinase Cδ participates in insulin-induced activation of PKB via PDK1

Abstract

PKCδ has been shown to be activated by insulin and to interact with insulin receptor and IRS. PKB(Akt) plays an important role in glucose transport and glycogen synthesis. In this study, we investigated the possibility that PKCδ may be involved in insulin-induced activation of PKB. Studies were conducted on primary cultures of rat skeletal muscle. PKB was activated by insulin stimulation within 5 min and reached a peak by 15–30 min. Insulin also increased the physical association between PKCδ with PKB and with PDK1. The insulin-induced PKCδ–PKB association was PI3K dependent. PKB–PKCδ association was accounted for by the involvement of PDK1. Overexpression of dominant negative PKCδ abrogated insulin-induced association of PKCδ with both PKB and PDK1. Blockade of PKCδ also decreased insulin-induced Thr308 PKB phosphorylation and PKB translocation. Moreover, PKCδ inhibition reduced insulin-induced GSK3 phosphorylation. The results indicate that insulin-activated PKCδ interacts with PDK1 to regulate PKB.