Atlantic salmon HNF-3/forkhead: cDNA sequence, evolution, expression, and functional analysis

We report the isolation and characterization of a cDNA encoding an HNF-3 fa mily member (as HNF-3) from Atlantic salmon (Salmo salar L,). The important functional domains of HNF-3 proteins that have been characterized previous ly are revealed by segments of high identity along the alignment of the asH NF-3 with winged helix/forkhend amino acid sequences isolated from other sp ecies. A comparison of asHNF-3 cDNA and genomic DNA indicated that there we re no introns present in the asHNF3 gene. Expression of asHNF-3 protein in adult salmon tissues was not exclusive to liver but was also present in the pancreas and intestine. An RT-PCR analysis performed on salmon development showed that asHNF3 expression is detectable before gastrulation at the mid blastula transition stage. Functional analysis of the asHNF-3 protein usin g a characterized HNF-3 consensus binding site demonstrated that the protei n can recognize and bind to specific HNF-3 consensus sequences. We also rep ort the identification of a novel HNF3 binding site in the promoter of the Atlantic salmon transferrin gene.