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Protein kinase C signalling in pancreatic beta-cells: cellular and molecular approaches
1Biomedical Sciences Division, King's College London, UK.
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.
Insights
Protein kinase C (PKC) research in pancreatic beta-cells faced challenges due to inhibitor selectivity. Advanced methods now clarify PKC
Area of Science:
- Endocrinology
- Cell Biology
- Biochemistry
Background:
- Protein kinase C (PKC) involvement in pancreatic beta-cell function has been investigated since the 1970s.
- Early research faced limitations due to non-selective PKC inhibitors and complexities with novel PKC isoforms.
Purpose of the Study:
- To elucidate the precise role of protein kinase C (PKC) in pancreatic beta-cell stimulus-response coupling.
- To overcome limitations of earlier methodologies in studying PKC signaling pathways.
Main Methods:
- Utilized early PKC inhibitors (polymyxin B, staurosporine) and their interpretational challenges.
- Employed phorbol ester-induced PKC downregulation and translocation studies.
- Incorporated second-generation selective PKC inhibitors (Ro 31-8220, Go 6976).
- Applied isoform-specific approaches, including antisense oligonucleotides and pseudosubstrate peptide inhibitors.
Main Results:
- Initial studies with non-selective inhibitors yielded ambiguous results regarding PKC's role.
- Phorbol ester studies provided insights but were complicated by the discovery of novel PKC isoforms.
- Selective inhibitors and isoform-specific depletion/inhibition methods have significantly clarified PKC's function.
- A comprehensive understanding of PKC's role in beta-cell stimulus-response coupling has been achieved.
Conclusions:
- The role of protein kinase C (PKC) in pancreatic beta-cell stimulus-response coupling is now better understood.
- Advancements in selective inhibition and isoform-specific targeting have been crucial for progress.
- Continued research utilizing refined methodologies will further enhance our knowledge of beta-cell signaling.