Estrogen receptor alpha (ERalpha) mediates stimulatory effects of estrogen on aromatase (CYP19) gene expression in human placenta.
A 246-bp region upstream of placenta-specific exon I.1 of the human aromatase (hCYP19) gene mediates placenta-specific, developmental, and O(2) regulation of expression. In this study, trophoblast differentiation and associated induction of CYP19 expression were prevented when cytotrophoblasts were cultured in phenol red-free medium containing charcoal-stripped serum or with the estrogen receptor (ER) antagonist, ICI 182,780, suggesting a stimulatory role of estrogen/ER. ERalpha protein was expressed in human trophoblasts and increased during syncytiotrophoblast differentiation, whereas ERbeta was undetectable. Mutational analysis revealed that an estrogen response element-like sequence (ERE-LS) at -208 bp is required for inductive effects of estradiol/ERalpha on hCYP19I.1 promoter activity in transfected COS-7 cells. Increased binding of syncytiotrophoblast compared with cytotrophoblast nuclear proteins to the ERE-LS was observed in vitro; however, ERalpha antibodies failed to supershift the complex and in vitro-transcribed/translated ERalpha did not bind. Nonetheless, chromatin immunoprecipitation assays in cultured trophoblasts revealed recruitment of endogenous ERalpha to the -255- to -155-bp region containing the ERE-LS before induction of hCYP19 expression; this was inhibited by ICI 182,780. Chromatin immunoprecipitation also revealed increased acetylated histone H3(K9/14) and decreased methylated histone H3(K9) associated with this region during trophoblast differentiation. These modifications were prevented when trophoblasts were incubated with ICI 182,780, suggesting that ERalpha recruitment to the -255- to -155-bp region promotes histone modifications leading to increased hCYP19 transcription. Thus, during trophoblast differentiation, estrogen/ERalpha exerts a positive feedback role, which promotes permissive histone modifications that are associated with induction of hCYP19 gene transcription.
Kumar
Premlata
P
Department of Biochemistry, The University of Texas Southwestern Medical Center at Dallas, 75390-9038, USA.
Kamat
Amrita
A
Mendelson
Carole R
CR
D001141:Aromatase / Q000235:genetics* / Q000378:metabolism; D020029:Base Pairing; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D002606:Charcoal; D002843:Chromatin / Q000378:metabolism; D003470:Culture Media; D004790:Enzyme Induction / Q000187:drug effects; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology; D047628:Estrogen Receptor alpha / Q000235:genetics / Q000378:metabolism*; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D000077267:Fulvestrant; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D006657:Histones / Q000378:metabolism; D006801:Humans; D010637:Phenolsulfonphthalein / Q000378:metabolism; D010920:Placenta / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D011247:Pregnancy; D011485:Protein Binding / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020218:Response Elements / Q000235:genetics; D012710:Serum Albumin, Bovine; D014327:Trophoblasts / Q000166:cytology / Q000187:drug effects / Q000201:enzymology
D002843:Chromatin; D003470:Culture Media; C506487:ESR1 protein, human; D047628:Estrogen Receptor alpha; D004967:Estrogens; D006657:Histones; D012333:RNA, Messenger; D002606:Charcoal; D000077267:Fulvestrant; D012710:Serum Albumin, Bovine; D004958:Estradiol; D001141:Aromatase; D010637:Phenolsulfonphthalein