The role of protein kinase C isoforms in insulin action

Insulin action on target tissues is mediated by specific tyrosine kinase re ceptors. Upon ligand binding insulin receptors autophosphorylate and phosph orylate intracellular substrates on tyrosine residues. These early events o f insulin action are followed by the activation of a number of enzymes, inc luding protein kinase C (PKC). At least 14 PKC isoforms have been identifie d and cloned to date. PKCs appear to play dual roles in insulin signaling. For instance, they are involved in transduction of specific insulin signals but also contribute to the generation of insulin resistance. In this artic le, we will analyze the experimental evidence addressing the mechanism by w hich insulin might activate individual PKC isoforms as well as the role of single PKCs in insulin-induced bioeffects. (J. Endocrinol. Invest. 24: 460- 467, 2001) (C) 2001, Editrice Kurtis.