Inhibition of Gsk3β activity improves β-cell function in c-KitWv/+ male mice

Lab Invest. 2012 Apr;92(4):543-55. doi: 10.1038/labinvest.2011.200. Epub 2012 Jan 16.

Abstract

Previous studies have shown that the stem cell marker, c-Kit, is involved in glucose homeostasis. We recently reported that c-Kit(Wv/+) male mice displayed the onset of diabetes at 8 weeks of age; however, the mechanisms by which c-Kit regulates β-cell proliferation and function are unknown. The purpose of this study is to examine if c-Kit(Wv/+) mutation-induced β-cell dysfunction is associated with downregulation of the phospho-Akt/Gsk3β pathway in c-Kit(Wv/+) male mice. Histology and cell signaling were examined in C57BL/6J/Kit(Wv/+) (c-Kit(Wv/+)) and wild-type (c-Kit(+/+)) mice using immunofluorescence and western blotting approaches. The Gsk3β inhibitor, 1-azakenpaullone (1-AKP), was administered to c-Kit(Wv/+) and c-Kit(+/+) mice for 2 weeks, whereby alterations in glucose metabolism were examined and morphometric analyses were performed. A significant reduction in phosphorylated Akt was observed in the islets of c-Kit(Wv/+) mice (P<0.05) along with a decrease in phosphorylated Gsk3β (P<0.05), and cyclin D1 protein level (P<0.01) when compared with c-Kit(+/+) mice. However, c-Kit(Wv/+) mice that received 1-AKP treatment demonstrated normal fasting blood glucose with significantly improved glucose tolerance. 1-AKP-treated c-Kit(Wv/+) mice also showed increased β-catenin, cyclin D1 and Pdx-1 levels in islets, demonstrating that inhibition of Gsk3β activity led to increased β-cell proliferation and insulin secretion. These data suggest that c-Kit(Wv/+) male mice had alterations in the Akt/Gsk3β signaling pathway, which lead to β-cell dysfunction by decreasing Pdx-1 and cyclin D1 levels. Inhibition of Gsk3β could prevent the onset of diabetes by improving glucose tolerance and β-cell function.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • B-Lymphocytes / physiology*
  • Benzazepines
  • Cell Proliferation
  • Cyclin D1 / metabolism
  • Diabetes Mellitus, Experimental / metabolism*
  • Glycogen Synthase Kinase 3 / metabolism*
  • Glycogen Synthase Kinase 3 beta
  • Homeodomain Proteins / metabolism
  • Indoles
  • Maf Transcription Factors, Large / metabolism
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Phosphorylation
  • Proto-Oncogene Proteins c-akt / metabolism*
  • Proto-Oncogene Proteins c-kit / physiology*
  • Trans-Activators / metabolism
  • beta Catenin / metabolism

Substances

  • Benzazepines
  • CTNNB1 protein, mouse
  • Ccnd1 protein, mouse
  • Homeodomain Proteins
  • Indoles
  • Maf Transcription Factors, Large
  • Mafa protein, mouse
  • Trans-Activators
  • beta Catenin
  • kenpaullone
  • pancreatic and duodenal homeobox 1 protein
  • Cyclin D1
  • Proto-Oncogene Proteins c-kit
  • Glycogen Synthase Kinase 3 beta
  • Gsk3b protein, mouse
  • Proto-Oncogene Proteins c-akt
  • Glycogen Synthase Kinase 3