Carbohydrate-Responsive Element-Binding Protein (ChREBP) Is a Negative Regulator of ARNT/HIF-1 beta Gene Expression in Pancreatic Islet beta-Cells

OBJECTIVE-Carbohydrate-responsive element-binding protein (ChREBP) is a transcription factor that has been shown to regulate carbohydrate metabolism in the liver and pancreatic beta-cells in response to elevated glucose concentrations. Because few genes have been identified so far as bona fide ChREBP-target genes, we have performed a genome-wide analysis of the ChREBP transcriptome in pancreatic beta-cells. RESEARCH DESIGN AND METHODS-Chromatin immunoprecipitation and high-density oligonucleotide filing arrays (ChIP-chip; Agilent Technologies) using MIN6 pancreatic beta-cell extracts were performed together with transcriptional and other analysis using standard techniques. RESULTS-One of the genes identified by ChIP-chip and linked to glucose sensing and insulin secretion was aryl hydrocarbon receptor nuclear translocator (ARNT)/hypoxia-inducible factor-1 beta (HIF-1 beta), a transcription factor implicated in altered gene expression and pancreatic-islet dysfunction in type 2 diabetes. We first confirmed that elevated glucose concentrations decreased ARNT/HIF-1 beta levels in INS-1 (832/13) cells and primary mouse islets. Demonstrating a role for ChREBP in ARNT gene regulation, ChREBP silencing increased ARNT mRNA levels in INS-1 (832/13) cells, and ChREBP overexpression decreased ARNT mRNA in INS-1 (832/13) cells and primary mouse islets. We demonstrated that ChREBP and Max-like protein X (MLX) bind on the ARNT/HIF-1 beta promoter on the proximal region that also confers the negative glucose responsiveness. CONCLUSIONS-These results demonstrate that, ChREBP acts as a novel repressor of the ARNT/HIF-1 beta gene and might contribute to P-cell dysfunction induced by glucotoxicity. Diabetes 59:153-160, 2010