title: Estrogen modulation of prolactin gene expression requires an intact mitogen-activated protein kinase signal transduction pathway in cultured rat pituitary cells.
abstract: Expression of the PRL gene is regulated by many factors, including cAMP, estradiol (E2), phorbol esters, epidermal growth factor (EGF), and TRH. The promoter region of the rat PRL gene has been shown to contain DNA sequences that are thought to support the direct interaction of estrogen receptors (ERs) with DNA. It is by this direct ER/DNA interaction that estrogen is thought to modulate expression of PRL. We report here that estrogeninduced PRL expression requires an intact mitogen-activated protein kinase (MAPK) signal transduction pathway in cultured rat pituitary cells (PR1 lactotroph and GH3 somatolactotroph cell lines). Interfering with the MAPK signaling cascade by inhibiting the activity of MAPK kinase (MEK) ablates the ability of estrogen to induce PRL mRNA and protein. In these cell lines, estrogen activates extracellular regulated protein kinases ERK-1 and ERK-2 enzyme activities maximally within 10 min of 1 nM E2 treatment. This activity is blocked by pretreatment of the cells with the MEK inhibitors PD98059 and UO126. The mechanism by which ERKs-1 and -2 are activated by estrogen appears to be independent of c-Src since the effects of estrogen on PRL gene expression are not affected by herbimycin A or PP1 administration. c-Raf-1 may be involved in the effects of E2 because estrogen causes the rapid and transient tyrosine phosphorylation of c-Raf-1. The ER antagonist ICI 182,780 blocks both ERK-1 and ERK-2 activation in addition to PRL protein and mRNA, implying a central role for the classical ER in the activation of the MAPK pathway resulting in PRL gene expression.
authors.affiliation: Department of Biochemistry, University of Wisconsin, Madison 53706, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Watters
authors.forename: T Y
authors.initials: TY
authors.lastname: Chun
authors.forename: Y N
authors.initials: YN
authors.lastname: Kim
authors.forename: P J
authors.initials: PJ
authors.lastname: Bertics
authors.forename: J
authors.initials: J
authors.lastname: Gorski
mesh_terms: D000818:Animals; D016227:Benzoquinones; D002070:Butadienes / Q000494:pharmacology; D002478:Cells, Cultured; D019938:Cyclin D1 / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004967:Estrogens / Q000378:metabolism / Q000494:pharmacology; D005260:Female; D005419:Flavonoids / Q000494:pharmacology; D005786:Gene Expression Regulation; D047029:Lactams, Macrocyclic; D048369:MAP Kinase Kinase 1; D020935:MAP Kinase Signaling System; D019950:Mitogen-Activated Protein Kinase 1 / Q000187:drug effects / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation; D010902:Pituitary Gland / Q000166:cytology* / Q000502:physiology; D011388:Prolactin / Q000235:genetics* / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D019908:Proto-Oncogene Proteins c-raf / Q000235:genetics / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D011809:Quinones / Q000494:pharmacology; D012333:RNA, Messenger / Q000187:drug effects; D051381:Rats; D011916:Rats, Inbred F344; D017828:Rifabutin / Q000031:analogs & derivatives; D015398:Signal Transduction; D013256:Steroids / Q000378:metabolism / Q000494:pharmacology; D014158:Transcription, Genetic; D014443:Tyrosine; D019061:src-Family Kinases / Q000187:drug effects / Q000378:metabolism
chemical_list: C108123:4-amino-5-(4-methylphenyl)-7-(tert-butyl)pyrazolo(3,4-d)pyrimidine; D016227:Benzoquinones; D002070:Butadienes; D004791:Enzyme Inhibitors; D004967:Estrogens; D005419:Flavonoids; D047029:Lactams, Macrocyclic; D009570:Nitriles; D011720:Pyrazoles; D011743:Pyrimidines; D011809:Quinones; D012333:RNA, Messenger; D013256:Steroids; C113580:U 0126; D019938:Cyclin D1; D017828:Rifabutin; D014443:Tyrosine; C020754:herbimycin; D011388:Prolactin; D019061:src-Family Kinases; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one