Rat Pit-1 stimulates transcription in vitro by influencing pre-initiation complex assembly.
The anterior pituitary-specific transcription factor, Pit-1, activates prolactin, growth hormone, TSH beta, growth hormone receptor genes and autoregulates the pit-1 gene. Its mechanism of transcription activation is unknown. Using immobilized DNA templates and order-of-addition transcription assays, it is shown that Pit-1 is required during pre-initiation complex assembly to activate the prolactin gene in vitro. Using prolactin promoters containing point mutations in the distal TATA box, it is also demonstrated that Pit-1 activation in vitro is not mediated simply by repressing the upstream, alternative promoter. Experiments show that a preformed class II pre-initiation complex is refractory to Pit-1 influence. The data indicate that Pit-1, and perhaps other members of the POU-protein family, activate transcription by influencing the type pre-initiation complex assembled on target promoters.
Sharp
Z D
ZD
Center for Molecular Medicine, University of Texas Institute of Biotechnology, San Antonio 78245.
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D011388:Prolactin / Q000096:biosynthesis* / Q000235:genetics; D011401:Promoter Regions, Genetic; D012313:RNA / Q000096:biosynthesis; D051381:Rats; D016385:TATA Box; D013698:Templates, Genetic; D050817:Transcription Factor Pit-1; D014157:Transcription Factors / Q000302:isolation & purification / Q000378:metabolism*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; C494187:POU1F1 protein, human; C494186:Pou1f1 protein, rat; D050817:Transcription Factor Pit-1; D014157:Transcription Factors; D012313:RNA; D011388:Prolactin