Glucose regulation of insulin gene expression requires the recruitment of p300 by the beta-cell-specific transcription factor Pdx-1.
Regulation of insulin gene expression in response to increases in blood glucose levels is essential for maintaining normal glucose homeostasis; however, the exact mechanisms by which glucose stimulates insulin gene transcription are not known. We have shown previously that glucose stimulates insulin gene expression by causing the hyperacetylation of histone H4 at the insulin promoter. We demonstrate that the histone acetyltransferase p300 is recruited to the insulin promoter only at high concentrations of glucose via its interaction with the beta-cell-specific transcription factor Pdx-1. Disruption of the function of the endogenous Pdx-1 abolishes the recruitment of p300 to the insulin gene promoter at high concentrations of glucose and results in decreased histone H4 acetylation and insulin gene expression. Furthermore, we demonstrate that the glucose-dependent interaction of Pdx-1 with p300 is regulated by a phosphorylation event that changes the localization of Pdx-1. Based on these data, we conclude that hyperacetylation of histone H4 at the insulin gene promoter in response to high concentrations of glucose depends on the beta-cell-specific transcription factor Pdx-1, which is required for the recruitment of the histone acetyltransferase p300 to the insulin gene promoter.
Mosley
Amber L
AL
Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536, USA.
Corbett
John A
JA
Ozcan
Sabire
S
D000107:Acetylation; D000123:Acetyltransferases / Q000032:analysis / Q000378:metabolism*; D000818:Animals; D001786:Blood Glucose / Q000502:physiology; D018797:Cell Cycle Proteins / Q000032:analysis / Q000378:metabolism*; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D005947:Glucose / Q000494:pharmacology* / Q000502:physiology; D051548:Histone Acetyltransferases; D006657:Histones / Q000378:metabolism; D018398:Homeodomain Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D047468:Immunoprecipitation; D007328:Insulin / Q000235:genetics*; D007515:Islets of Langerhans / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D019319:Okadaic Acid / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000235:genetics; D051381:Rats; D015534:Trans-Activators / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor
D000123:Acetyltransferases; D001786:Blood Glucose; D018797:Cell Cycle Proteins; D005947:Glucose; D051548:Histone Acetyltransferases; D006657:Histones; D018398:Homeodomain Proteins; D007328:Insulin; D019319:Okadaic Acid; D015534:Trans-Activators; D014157:Transcription Factors; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor; C084010:pancreatic and duodenal homeobox 1 protein