ABSTRACT
Institut de Chimie B6, B-4000 San-Tilman, Belgium 'Present address: Pediatrics W-140 (Ward 12-104), Nonhwestem University Medical
School, 303 E. Chicago Ave., Chicago, Illinois 60611-3008, USA 1 Depanment of Zoology, The GeorgeS. Wise Faculty of Life Sciences, Tel-Aviv
University, Ramat Aviv, Tel-Aviv 69978, Israel
To date, little research has been done to consider the process involved in regulating prolactin (PRL) gene transcription in fish species. Comparative work carried out shows that 5'-flanking sequences of PRL genes in mammals differ quite extensively from those in two teleostean fish species: the tilapia and chinook salmon. Nevertheless, several potential binding sites for the transcription factor Pit-1, which are known to be involved in PRL gene expression in mammals, are found in the 5'- flanking regions of the salmon and tilapia PRL genes. This suggests the factor may possibly play a role in fish PRL gene expression. Recent data indicate that Pit-1 is conserved quite extensively among vertebrates. Studies on the salmon and tilapia PRL genes point to the conservation of part of the molecular mechanisms involved in pituitary-specific expression of the PRL genes from teleosts to mammals and, more particularly, to the role of Pit-1. However, the species-specific patterns of PRL gene expression that do exist might involve species-specific factors that have yet to be identified. Or, alternatively, they could concern species-specific interactions of Pit-1 with the transcription machinery.
