Pit-1/GHF-1 binds to TRH-sensitive regions of the rat thyrotropin beta gene.
Three regions within the 5'-flanking region of the TSH beta gene have A-T-rich sequences which have sequence similarity to binding sites for the pituitary-specific POU domain transcription factor Pit-1/GHF-1. These three regions have been termed TSH A (-274 to -258 bp), TSH B (-336 to -326 bp), and TSH C (-402 to -384 bp). TSH A and TSH C are able to confer 2-6-fold TRH stimulation to the heterologous viral thymidine kinase (tk) promoter in transient expression assays in GH3 pituitary cells; TSH C can confer a 3-10-fold increase in basal enhancer activity as well. TSH A, B, and C DNAs all bound Pit-1 from GH3 cell nuclear extracts, based on gel mobility shift analysis in which antibody against Pit-1 prevented the formation of specific DNA-GH3 nuclear protein complexes. TSH A and TSH C also each formed several additional DNA-nuclear protein complexes which were not observed with TSH B. Some of these complexes may contain Pit-1 as their formation was inhibited by the addition of Pit-1 antibody; other complexes, however, were not altered by antibody treatment. All three A-T-rich elements bound in vitro translated Pit-1, with calculated affinities of 360 (A), 125 (B), and 38 (C) nM, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
Mason
M E
ME
Department of Medicine, University of Virginia Medical Center, Charlottesville 22903.
Friend
K E
KE
Copper
J
J
Shupnik
M A
MA
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D011401:Promoter Regions, Genetic; D051381:Rats; D013937:Thymidine Kinase / Q000235:genetics; D013972:Thyrotropin / Q000235:genetics*; D013973:Thyrotropin-Releasing Hormone / Q000378:metabolism*; D050817:Transcription Factor Pit-1; D014157:Transcription Factors / Q000378:metabolism*
D004268:DNA-Binding Proteins; D009838:Oligodeoxyribonucleotides; C494187:POU1F1 protein, human; C494186:Pou1f1 protein, rat; D050817:Transcription Factor Pit-1; D014157:Transcription Factors; D013973:Thyrotropin-Releasing Hormone; D013972:Thyrotropin; D013937:Thymidine Kinase