Isolation of Sparus auratus prolactin gene and activity of the cis-acting regulatory elements.

Abstract A sea bream prolactin (sbPRL) gene was isolated using a prolactin cDNA fragment, generated by PCR as a probe. The gene analyzed comprises 3.5 kb of DNA containing five exons as described previously for other fish PRL genes. Analysis of 1.0 kb of the proximal promoter sequence reveals a consensus TATAA box, up to seven (A/T) 3 NCAT consensus motifs for binding of the pituitary-specific factor Pit-1 and putative CREB and GATA binding sites. CHO culture cells co-transfected with a sbPRL promoter sequence and a sea bream Pit-1 cDNA expression plasmid showed expression of a linked luciferase reporter gene. Transient expression experiments with 5 ′ -delection mutants reveals at least three regulatory regions on the sbPRL gene, two with a stimulatory effect on transcription and one with apparent inhibitory effect. From a comparative point of view, this study of PRL gene in Sparus auratus , correlates well with those previously published on tilapia and rainbow trout. The molecular data reported will be useful for comparative analysis of gene regulation in the GH/PRL gene family in teleosts.