Inhibition of gluconeogenic genes by calcium-regulated heat-stable protein 1 via repression of peroxisome proliferator-activated receptor α

J Biol Chem. 2011 Nov 25;286(47):40584-94. doi: 10.1074/jbc.M111.232918. Epub 2011 Oct 11.

Abstract

Gluconeogenesis contributes to insulin resistance in type 1 and type 2 diabetes, but its regulation and the underlying molecular mechanisms remain unclear. Recently, calcium-regulated heat-stable protein 1 (CARHSP1) was identified as a biomarker for diabetic complications. In this study, we investigated the role of CARHSP1 in hepatic gluconeogenesis. We assessed the regulation of hepatic CARHSP1 expression under conditions of fasting and refeeding. Adenovirus-mediated CARHSP1 overexpression and siRNA-mediated knockdown experiments were performed to characterize the role of CARHSP1 in the regulation of gluconeogenic gene expression. Here, we document for the first time that CARHSP1 is regulated by nutrient status in the liver and functions at the transcriptional level to negatively regulate gluconeogenic genes, including the glucose-6-phosphatase catalytic subunit (G6Pc) and phosphoenolpyruvate carboxykinase 1 (PEPCK1). In addition, we found that CARHSP1 can physically interact with peroxisome proliferator-activated receptor-α (PPARα) and inhibit its transcriptional activity. Both pharmacological and genetic ablations of PPARα attenuate the inhibitory effect of CARHSP1 on gluconeogenic gene expression in hepatocytes. Our data suggest that CARHSP1 inhibits hepatic gluconeogenic gene expression via repression of PPARα and that CARHSP1 may be a molecular target for the treatment of diabetes.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Catalytic Domain
  • DNA-Binding Proteins / deficiency
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Down-Regulation / genetics
  • Gene Knockdown Techniques
  • Gene Silencing*
  • Gluconeogenesis / genetics*
  • Glucose-6-Phosphatase / chemistry
  • Glucose-6-Phosphatase / genetics
  • HEK293 Cells
  • Hep G2 Cells
  • Hepatocytes / metabolism
  • Humans
  • Male
  • Mice
  • Mice, Inbred C57BL
  • PPAR alpha / deficiency*
  • PPAR alpha / genetics*
  • PPAR alpha / metabolism
  • Phosphoenolpyruvate Carboxylase / genetics
  • Phosphoproteins / deficiency
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism*
  • Promoter Regions, Genetic / genetics
  • Transcription Factors / deficiency
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*

Substances

  • CARHSP1 protein, human
  • DNA-Binding Proteins
  • PPAR alpha
  • Phosphoproteins
  • Transcription Factors
  • Glucose-6-Phosphatase
  • Phosphoenolpyruvate Carboxylase