Specification of unique Pit-1 activity in the hGH locus control region.
The human GH (hGH) gene cluster is regulated by a remote 5' locus control region (LCR). HSI, an LCR component located 14.5 kb 5' to the hGH-N promoter, constitutes the primary determinant of high-level hGH-N activation in pituitary somatotropes. HSI encompasses an array of three binding sites for the pituitary-specific POU homeodomain factor Pit-1. In the present report we demonstrate that all three Pit-1 sites in the HSI array contribute to LCR activity in vivo. Furthermore, these three sites as a unit are fully sufficient for position-independent and somatotrope-restricted hGH-N transgene activation. In contrast, the hGH-N transgene is not activated by Pit-1 sites native to either the hGH-N or rat (r)GH gene promoters. These findings suggest that the structures of the Pit-1 binding sites at HSI specify distinct chromatin-dependent activities essential for LCR-mediated activation of hGH in the developing pituitary.
Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA.
Brian M
BM
Shewchuk
Stephen A
SA
Liebhaber
Nancy E
NE
Cooke
D000818:Animals; D001483:Base Sequence; D004247:DNA; D004268:DNA-Binding Proteins / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D004742:Enhancer Elements, Genetic; D013006:Growth Hormone / Q000235:genetics*; D006801:Humans; D019901:Locus Control Region; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D010902:Pituitary Gland / Q000378:metabolism; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050817:Transcription Factor Pit-1; D014157:Transcription Factors / Q000378:metabolism*
D004247:DNA; D004268:DNA-Binding Proteins; D013006:Growth Hormone; D050817:Transcription Factor Pit-1; D014157:Transcription Factors; C494187:POU1F1 protein, human; C494185:Pou1f1 protein, mouse