Analysis of the rat hepatocyte nuclear factor (HNF) 1 gene promoter: synergistic activation by HNF4 and HNF1 proteins.

Hepatocyte nuclear factor (HNF) 1 is a key transcription factor involved in the expression of many liver-specific genes. We have isolated and characterized the promoter region of the rat HNF1 gene. Transfection experiments revealed that a short region between -118 and -8 is crucial for cell type-specific expression of the HNF1 gene in the hepatoma cell line, HepG2 cells. This region contains two positive cis-elements: site A, to which the transcription factor HNF4 protein can bind, and site B, to which the HNF1 protein can bind. Mutational analyses of these sites and cotransfection assays suggested that the HNF4 protein and HNF1 protein can transactivate the HNF1 gene.