The Ubiquitous Transcription Factor Oct-1 and the Liver-Specific Factor HNF-1 Are Both Required to Activate Transcription of a Hepatitis B Virus Promoter

Abstract

The liver-specific transcription factor HNF-1 activates transcription of several mammalian hepatocytespecific genes. The hepatitis B virus preS1 promoter shows hepatocyte specificity, which has been ascribed to binding of HNF-1 to a cognate DNA sequence upstream of the TATA box. We show here that there is an adjacent site that binds the ubiquitous transcription factor Oct-1. Both the Oct-1 and HNF-1 sites are necessary for liver-specific transcription of the preS1 promoter, but neither site alone activates transcription. The Oct-1 site is also necessary for activation of the preS1 promoter in HeLa cells expressing transfected HNF-1. Our results show that while Oct-1 is not restricted to hepatocytes, it nevertheless can play a critical role in the expression of a liver-specific gene.