The promoter of the salmon insulin-like growth factor I gene is activated by hepatocyte nuclear factor 1

Hepatocyte nuclear factor 1 (HNF-1) was found to have a potent stimulatory action on the activity of the promoter of the salmon insulin-like growth factor I (IGF-I) gene in transient transfection experiments. This liver-enriched transcription factor was shown to bind to an element in the proximal region of the promoter with distinct nucleotide sequence homology to the HNF-1 consensus binding sequence. Mutating this sequence to a variant no longer capable of HNF-1 binding resulted in the loss of the stimulatory effect. Since the sequence of the HNF-1 binding site is conserved in all mammalian, avian, and amphibian species from which the IGF-I promoter sequences have been derived to date, we propose that HNF-1 may be an important regulator of IGF-I gene expression in all of these species.