Protein kinase C signalling in pancreatic beta-cells: cellular and molecular approaches.

Abstract

Since the identification of protein kinase C (PKC) in the late 1970s, there have been many attempts to define its involvement in pancreatic beta-cell responses to physiological secretagogues. Early studies made use of PKC inhibitors such as polymyxin B and staurosporine, but their lack of selectivity made results difficult to interpret. Phorbol ester-induced PKC downregulation and measurements of PKC translocation within beta-cells provided useful information, but these studies were further complicated by the identification of novel PKC isoforms which do not possess diacylglycerol-binding sites or do not translocate upon stimulation. Second-generation PKC inhibitors, such as Ro 31-8220 and Go 6976, show improved selectivity and have helped clarify the situation. In addition, the use of antisense oligonucleotides or pseudosubstrate peptide inhibitors to selectively deplete or inhibit particular PKC isoforms has provided valuable information. The application of these varied methodologies has allowed us to develop a fuller understanding of the role played by PKC in beta-cell stimulus-response coupling.