Pit-1 mediates cell-specific and cAMP-induced transcription of the tilapia GH gene.
Expression of the tilapia growth hormone (tiGH) gene is pituitary-specific and controlled by intracellular cAMP levels. DNaseI protection experiments allowed us to identify four Pit-1 binding sites in the tiGH - 465/ + 19 region. Deletion and mutagenesis analysis revealed that the - 131/+ 19 region, containing two Pit-1 sites, or four copies of the most proximal site tiGHF1 fused to the heterologous Tk promoter, confer high level expression in rat pituitary cells and direct transcription in non-pituitary cells only after expression of rat Pit-1. We show that a tilapia pituitary factor specifically binds to site tiGHF1 and obtained a partial cDNA sequence coding for tilapia Pit-1. The cAMP stimulation is mediated by the proximal (- 131/- 31) promoter region. It is Pit-1-dependent and requires the tiGHF1 site. In addition, four copies of this site confer cAMP inducibility to the Tk promoter in GC cells.
Sekkali
B
B
Laboratoire de Biologie Moléculaire et de Génie Génétique, Université de Liège, Institut de Chimie B6, Sart-Tilman, Belgium.
Belayew
A
A
Bortolussi
M
M
Martial
J A
JA
Muller
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D000242:Cyclic AMP / Q000494:pharmacology*; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D013006:Growth Hormone / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics; D051381:Rats; D016415:Sequence Alignment; D017210:Tilapia / Q000235:genetics*; D050817:Transcription Factor Pit-1; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects
D004268:DNA-Binding Proteins; C494186:Pou1f1 protein, rat; D050817:Transcription Factor Pit-1; D014157:Transcription Factors; D013006:Growth Hormone; D000242:Cyclic AMP