Mouse NTCP is directly transactivated via a conserved HNF-4α element in the proximal promoter region, with further co-activation by PGC-1α

Background & Aim: Sodium taurocholate co-transporting polypeptide (Ntcp), a 50 kDa basolaterally localized membrane transporter, is the major transport system for conjugated bile acids. Induction of cholestasis in rats leads to down-regulation of Ntcp involving decreased HNF–1α binding to a proximal element within the minimal promoter. Mouse Ntcp promoter is missing this proximal HNF–1α element and is activated by a distal HNF–1α cis element (Geier et al. AJP 2005, in press). In addition, other potential cis elements not previously identified are also likely to regulate the mouse gene. We therefore functionally…