Biochemical and Biophysical Research Communications, Vol.410, No.2, 345-350, 2011
Suppression of FAT/CD36 mRNA by human growth hormone in pancreatic beta-cells
Fatty acid-induced damage in pancreatic beta-cells is assumed to play an important role in the development of type 2 diabetes. Lactogens (prolactin, placental lactogen and growth hormone) improve beta-cell survival via STAT5 activation but the molecular targets are incompletely characterized. The aim of this study was to examine the effect of human growth hormone (hGH) on mRNAs of fatty acid transport and binding proteins expressed in pancreatic beta-cells, and to examine this in relation to beta-cell survival after exposure to fatty acids. hGH decreased mRNA levels of FAT/CD36, whereas mRNAs of GPR40, FASN, FABP2, FATP1 and FATP4 were unchanged. RNAi against FAT/CD36 decreased fatty acid-induced apoptosis. Overexpression of constitutively active STAT5 was able to mimic hGH's suppression of FAT/CD36 expression, whereas dominant negative STAT5 was unable to block the effect of hGH indicating that STAT5 did not bind directly to the FAT/CD36 promoter. The hGH-mediated suppression of FAT/CD36 mRNA was associated with a decrease in palmitate uptake and fatty acid-induced basal hyper-secretion of insulin resulting in improved glucose-stimulated insulin secretion. This study suggests that hGH can protect beta-cells against fatty acid-induced damages. (C) 2011 Elsevier Inc. All rights reserved.
Keywords:Pancreatic beta-cell;Growth hormone;Lactogen;FAT/CD36;Apoptosis;Signal transducer and activator of transcription 5 (STAT5);GPR40;FABP2;FATP1;FATP4