201. Ped/pea-15 Regulates Glucose-Induced Insulin Secretion by Restraining Potassium Channel Expression in Pancreatic Beta-Cells.
- Author
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Oriente, Francesco, Miele, Claudia, Raciti, Gregory A., Cassese, Angela, Romano, Chiara, Giacco, Ferdinando, Paturzo, Flora, Bosch, Fatima, Pujol, Anna, Chneiweiss, HervÈ, Formisano, Pietro, and Beguinot, Francesco
- Subjects
PHOSPHOPROTEINS ,DIABETES ,ASTROCYTES ,POTASSIUM channels ,PANCREATIC beta cells ,TYPE 2 diabetes ,INSULIN resistance ,GLUCOSE - Abstract
The phosphoprotein enriched in diabetes/phosphoprotein enriched in astrocytes (ped/pea-15) gene is overexpressed in tissues of individuals with type 2 diabetes. Moreover, transgenic mice ubiquitously overexpressing ped/pea-15 feature impaired glucose tolerance and insulin resistance. We have now generated transgenic mice with beta-cell specific overexpressing of ped/pea-15 (beta-tg). Beta-tg mice exhibited decreased glucose tolerance but were not insulin-resistant. However, they showed impaired insulin response to hyperglycemia. Islets from the beta-tg also exhibited little response to glucose. mRNAs encoding the Surl and Kir6.2 potassium channel subunits and their upstream regulator Foxa2 were specifically reduced in these islets. Overexpression of ped/pea-15 inhibited the induction of the atypical PKCzeta by glucose in mouse islets and in beta-cells of the MIN-6 and INS-1 lines. Rescue of PKCzeta activity elicited recovery of the expression of the Sur1, Kir6.2 and Foxa2 genes and of glucose-induced insulin-secretion in PED/PEA- 15 overexpressing beta-cells. Islets from ped/pea-15 null mice exhibited a 2-fold increased activation of PKCzeta by glucose and increased abundance of the Surl, Kir6.2 and Foxa2 mRNAs and enhanced glucose effect on insulin secretion. In conclusion, ped/pea-15 is an endogenous regulator of glucose-induced insulin secretion, which restrains potassium channel expression in pancreatic beta-cells. Overexpression of ped/pea-15 dysregulates beta-cell function and is sufficient to impair glucose tolerance in mice. [ABSTRACT FROM AUTHOR]
- Published
- 2007