Mutations in pancreatic duodenal homeobox (PDX1) are associated with diabetes in humans. Pdx1-haploinsufficient mice develop diabetes due to an increase in β-cell death leading to reduced β-cell mass. In order to define the molecular link between Pdx1 deficiency and β-cell death, Pdx1 haploinsufficient mice in which the genes for the BH3-only molecules Bim and Puma had been ablated were studied on a high fat diet. Compared to Pdx1+/- mice, animals haploinsufficient for both Pdx1 and Bim or Puma genes showed improved glucose tolerance, enhanced β-cell mass and reduction in the number of TUNEL positive cells in islets. These results suggest that Bim and Puma ablation improves β-cell survival in Pdx1+/- mice. To explore the mechanisms responsible for these findings Pdx1 gene expression was knocked down in mouse MIN6 insulinoma cells resulting in apoptotic cell death that was found to be associated with increased expression of BH3-only molecules Bim and Puma. If the upregulation of Bim and Puma that occurs during Pdx1 suppression was prevented, apoptotic β-cell death was reduced in vitro. These results suggest that Bim and Puma play important role in β-cell apoptosis in Pdx1-deficient diabetes.
- Received October 1, 2013.
- Accepted March 17, 2014.
- © 2014 by the American Diabetes Association.
Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered. See http://creativecommons.org/licenses/by-nc-nd/3.0/ for details.