2015 Volume 52 Issue 1 Pages 42-51
The PRL regulatory element binding protein (PREB) is a transcription factor that specifically binds to a Pit-1 binding element in the PRL promoter to regulate PRL gene expression in mammals. However, it is unknown whether chicken PREB involves the expression of PRL mRNA or not. This study aimed to clone and characterize the chicken PREB gene and to investigate the mRNA expression during embryogenesis and different reproductive stages. Based on the conserved sequence of the human, rats and mouse, primers pairs were designed and applied to amplify the PREB cDNA fragment. After sequencing of PCR products, 5′- and 3′- end of mRNA were amplified and determined. To identify the structure of the PREB gene, PCR amplification was conducted. The chicken PREB gene consisted of 9 exons and 8 introns and encoded for a 411 amino acid protein. The expression of PREB mRNA in the anterior pituitary gland was measured during embryogenesis and at different reproductive stages. PREB mRNA was detectable at embryonic day 12. Significant increase of levels of PREB mRNA was detected at embryonic day 18 and a maximum level was detected at day 1 of chick. In adult Silkie hens, the lowest level of PREB mRNA was detected in non-photostimulated hens whereas the highest level was observed in incubating hens. Since both the expression of PREB mRNA and PRL mRNA show a similar profile, PREB might be involved in expression of PRL mRNA. An alternative-splicing isoform, which lacks exon 7, was also detected. Because the predicted translated protein originating from this splicing isoform lacked most of the region of WD3 repeat region, this isoform may either have no function or have an alternative function. The results of this study support the possibility of involvement of PREB in PRL mRNA expression in the chicken anterior pituitary gland.
