title: Carbohydrate-responsive element-binding protein (ChREBP) is a negative regulator of ARNT/HIF-1beta gene expression in pancreatic islet beta-cells.
abstract: 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.
  
  
  METHODS
  Chromatin immunoprecipitation and high-density oligonucleotide tiling 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-1beta (HIF-1beta), 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-1beta 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-1beta 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-1beta gene and might contribute to beta-cell dysfunction induced by glucotoxicity.
authors.affiliation: Department of Endocrinology and Metabolic Medicine, Division of Medicine, Imperial College, London, U.K.
authors.forename: Nafeesa A
authors.initials: NA
authors.lastname: Noordeen
authors.forename: Tarnjit K
authors.initials: TK
authors.lastname: Khera
authors.forename: Gao
authors.initials: G
authors.lastname: Sun
authors.forename: E Rebecca
authors.initials: ER
authors.lastname: Longbottom
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Pullen
authors.forename: Gabriela
authors.initials: G
authors.lastname: da Silva Xavier
authors.forename: Guy A
authors.initials: GA
authors.lastname: Rutter
authors.forename: Isabelle
authors.initials: I
authors.lastname: Leclerc
mesh_terms: D000818:Animals; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator / Q000037:antagonists & inhibitors / Q000235:genetics*; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D018929:Cell Culture Techniques; D002843:Chromatin / Q000302:isolation & purification; D017931:DNA Primers; D005786:Gene Expression Regulation / Q000502:physiology*; D005947:Glucose / Q000633:toxicity; D050417:Insulin-Secreting Cells / Q000166:cytology / Q000502:physiology*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009687:Nuclear Proteins / Q000378:metabolism / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D051381:Rats; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D014162:Transfection
chemical_list: C497397:Arnt protein, mouse; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D002843:Chromatin; D017931:DNA Primers; C506001:Mlxipl protein, mouse; D009687:Nuclear Proteins; D014157:Transcription Factors; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D012313:RNA; D005947:Glucose