Differential binding of GH3 and pituitary protein extracts to the estrogen-dependent enhancer of the rat prolactin gene.
Extracts of two prolactin (PRL) producing cells (GH3 cells and rat pituitary tumors) were compared for their ability to bind to a PRL DNA fragment that contained sequences important for estrogen enhancement of PRL transcription. The ability of estradiol (E2) to alter concentrations of existing PRL enhancer binding proteins or to promote the appearance of additional binding proteins was also examined. When diethylstilbestrol (DES)-induced pituitary tumor extracts were examined for protein binding to the same DNA fragment, a different banding pattern was observed than the banding pattern seen using protein extracts from GH3 cells, suggesting that PRL DNA binding proteins differ between GH3 cells and rat pituitary tumors. The differences in PRL DNA binding may result from the fact that approximately 20% of GH3 cells are lactotrophs, while 80% of DES-induced pituitary tumor cells are lactotrophs. In addition, no change in the relative concentrations of proteins binding to the upstream regulatory element was observed following treatment of GH3 cells with E2.
Meier
D A
DA
Department of Biochemistry, University of Wisconsin, Madison 53706.
Gorski
J
J
D000818:Animals; D001943:Breast Neoplasms / Q000473:pathology; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D004054:Diethylstilbestrol / Q000633:toxicity; D004742:Enhancer Elements, Genetic; D004958:Estradiol / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D005796:Genes; D006367:HeLa Cells / Q000737:chemistry; D006801:Humans; D009363:Neoplasm Proteins / Q000302:isolation & purification / Q000378:metabolism*; D010911:Pituitary Neoplasms / Q000139:chemically induced / Q000473:pathology; D011388:Prolactin / Q000235:genetics*; D051381:Rats; D014407:Tumor Cells, Cultured / Q000737:chemistry / Q000187:drug effects
D004268:DNA-Binding Proteins; D009363:Neoplasm Proteins; D004958:Estradiol; D004054:Diethylstilbestrol; D011388:Prolactin