Insulin protects islets from apoptosis via Pdx1 and specific changes in the human islet proteome
| Autor: | Emilyn U. Alejandro, Ernesto Bernal-Mizrachi, Garth L. Warnock, M. Alan Permutt, Zhiqiang Han, Kenneth S. Polonsky, Tatyana B. Kalynyak, Raymond R. Townsend, Julia Gross, Hong Li, Jennifer L. Beith, James D. Johnson |
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| Rok vydání: | 2006 |
| Předmět: |
Proteomics
endocrine system medicine.medical_specialty endocrine system diseases Proto-Oncogene Proteins c-akt medicine.medical_treatment Blotting Western Fluorescent Antibody Technique Apoptosis Biology Islets of Langerhans Mice Internal medicine Insulin receptor substrate medicine Animals Humans Insulin Protein kinase B Homeodomain Proteins Analysis of Variance Multidisciplinary Dose-Response Relationship Drug Biological Sciences IRS2 Insulin oscillation Insulin receptor Endocrinology Trans-Activators biology.protein PDX1 |
| Zdroj: | Proceedings of the National Academy of Sciences. 103:19575-19580 |
| ISSN: | 1091-6490 0027-8424 |
| Popis: | Insulin is both a hormone regulating energy metabolism and a growth factor. We and others have shown that physiological doses of insulin initiate complex signals in primary human and mouse β-cells, but the functional significance of insulin's effects on this cell type remains unclear. In the present study, the role of insulin in β-cell apoptosis was examined. Exogenous insulin completely prevented apoptosis induced by serum withdrawal when given at picomolar or low nanomolar concentrations but not at higher concentrations, indicating that physiological concentrations of insulin are antiapoptotic and that insulin signaling is self-limiting in islets. Insulin treatment was associated with the nuclear localization of Pdx1 and the prosurvival effects of insulin were largely absent in islets 50% deficient in Pdx1, providing direct evidence that Pdx1 is a signaling target of insulin. Physiological levels of insulin did not increase Akt phosphorylation, and the protective effects of insulin were only partially altered in islets lacking 80% of normal Akt activity, suggesting the presence of additional insulin-regulated antiapoptotic pathways. Proteomic analysis of insulin-treated human islets revealed significant changes in multiple proteins. Bridge-1, a Pdx1-binding partner and regulator of β-cell survival, was increased significantly at low insulin doses. Together, these data suggest that insulin can act as a master regulator of islet survival by regulating Pdx1. |
| Databáze: | OpenAIRE |
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