Hepatocyte nuclear factor 4 (HNF4) binding sites in the salmon HNF1 promoter

We report the isolation and sequencing of a 1100-bp DNA fragment containing the salmon Hepatocyte Nuclear Factor 1 gene (sHNF1) promoter. The sHNF1 promoter cloned upstream of the chloramphenicol acetyl transferase (CAT) encoding gene is shown to be active in two cell lines of hepatic origin. DNaseI footprint analysis of the proximal 400 bp reveals several protein-binding sites, including a CCAAT box, a potential site for Sp1, and three potential HNF4 binding sites. The sequence does not contain any canonical TATA box or initiator and sHNF1 transcription is initiated at four different sites spanning a region of 56 bp. Sequence comparison with the Xenopus laevis HNF1 promoter sequence did not show any significant similarity except in the region overlapping two of the potential HNF4 binding sites.