ChREBP binding to fatty acid synthase and L-type pyruvate kinase genes is stimulated by glucose in pancreatic beta-cells

摘要

Pancreatic beta-cell dysfunction is central to the pathogenesis of type 2 diabetes and may involve secretory failure through glucolipotoxity. The relative importance of the transcription factors carbohydrate-responsive element binding protein (ChREBP), sterol-responsive element binding protein-1c (SREBP-1c), and upstream stimulatory factor (USF) in the induction of lipogenic genes by glucose remains unclear. By confocal imaging, we show that ChREBP translocates to the nucleus in MIN6 beta cells in response to glucose. Both ChREBP and SREBP-1c were required for the induction of the fatty acid synthase (FAS) promoter by glucose, and chromatin immuno-precipitation (ChIP) assay revealed that glucose induced the binding of both ChREBP and SREBP-1c to the FAS promoter without affecting USF2 binding. By contrast, ChIP assay revealed that high glucose prompted direct binding of ChREBP, but not SREBP-1c or USF2, to the liver-type pyruvate kinase (L-PK) promoter. This event was indispensable for the induction of the L-PK gene by glucose, as demonstrated by RNA silencing, single-cell promoter analysis, and quantitative real-time PCR. We conclude that ChREBP is a critical regulator of lipogenic genes in the beta cell and may play a role in the development of glucolipotoxicity and beta cell failure through alteration of gene expression in type 2 diabetes.