The turkey transcription factor Pit-1/GHF-1 can activate the turkey prolactin and growth hormone gene promoters in vitro but is not detectable in lactotrophs in vivo.
The transcription factor Pit-1/GHF-1 plays an important role in regulating the prolactin (Prl) and growth hormone (GH) genes in mammals. In this study, the role that Pit-1 plays in regulating the prolactin and growth hormone genes in avian species was examined by cotransfection assays and immunofluorescence staining of pituitary sections. In cotransfection assays, turkey Pit-1 activated the turkey Prl, turkey GH, and rat Prl promoters 3.8-, 3.7-, and 12.5-fold, respectively. This activation was comparable to rat Pit-1 activation of these same promoters. A point mutation in the turkey Pit-1 cDNA, which changed leu-219 to ser-219, resulted in a 2-, 2-, and 10-fold reduction in the activation of the turkey Prl, turkey GH, and rat Prl promoters, respectively. Unexpectedly, coexpression of tPit-1 (leu-219) and tPit-1(ser-219) activated turkey Prl and rat Prl promoters 9.4- and 35.9-fold, respectively, but had no effect on the turkey GH promoter. Dual-label immunofluorescence analysis of turkey pituitary sections revealed that Pit-1 was not detectable in prolactin-staining cells but was detectable in GH-staining cells. Taken together, these data indicate that in the domestic turkey, Pit-1 can activate the turkey Prl promoter in vitro, but does not appear to play a role in regulating Prl gene expression in vivo. Pit-1, however, still likely plays a role in regulating GH gene expression.
Weatherly
K L
KL
Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, Virginia 24061-0306, USA.
Ramesh
R
R
Strange
H
H
Waite
K L
KL
Storrie
B
B
Proudman
J A
JA
Wong
E A
EA
D024506:5' Flanking Region; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002467:Cell Nucleus / Q000737:chemistry; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000032:analysis / Q000235:genetics / Q000494:pharmacology*; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation / Q000187:drug effects; D005822:Genetic Vectors; D013006:Growth Hormone / Q000032:analysis / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D010902:Pituitary Gland / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D011388:Prolactin / Q000032:analysis / Q000235:genetics*; D011401:Promoter Regions, Genetic; D051381:Rats; D050817:Transcription Factor Pit-1; D014157:Transcription Factors / Q000032:analysis / Q000235:genetics / Q000494:pharmacology*; D014162:Transfection; D014422:Turkeys / Q000235:genetics*
D004268:DNA-Binding Proteins; D013006:Growth Hormone; D011388:Prolactin; D050817:Transcription Factor Pit-1; D014157:Transcription Factors; C494187:POU1F1 protein, human; C494185:Pou1f1 protein, mouse; C494186:Pou1f1 protein, rat