Vaspin is a novel target gene of hepatic CCAAT-enhancer-binding protein

Abstract

Vaspin, initially identified in visceral adipose tissue, is an adipokine, and administration of recombinant vaspin leads to lowering of the endoplasmic reticulum stress which is elevated in obesity or enhancement of insulin sensitivity. CCAAT/enhancer binding protein (C/EBP), as a basic leucine zipper transcription factor, plays a critical role in adipocyte development and glucose and lipid metabolisms in liver. The present study aimed to investigate the effect of C/EBPα on vaspin gene expression. The expression of hepatic vaspin was markedly decreased in liver-specific C/EBPα knockout mice. A reporter assay indicated that two C/EBP-responsive elements (CEBPREs) are necessary for C/EBPα-dependent induction of vaspin promoter activities. Furthermore, electrophoretic mobility shift assay showed that C/EBPα in mouse liver is capable of directly binding the two CEBPREs. These results suggest that C/EBPα positively regulates hepatic vaspin expression through two functional CEBPREs. Thus, vaspin is a novel C/EBPα target gene in the liver.