Expression of estrogen receptor coactivators in the rat uterus.
Nuclear receptor coactivators associate in a ligand-dependent manner with estrogen receptors (ER) and other nuclear receptors, and they enhance ligand-dependent transcriptional activation. This study examined basal coactivator expression in rat uterus to investigate if expression of these genes is regulated by estradiol-17 beta or tamoxifen. Ovariectomized mature and immature rats were injected with estradiol-17 beta, tamoxifen, or vehicle (i.e., sesame oil) alone. Uteri were collected and analyzed for changes in coactivator mRNA expression using Northern blot and in situ hybridization analyses. Constitutive uterine mRNA expression of switch protein for antagonist (SPA), SRC-1, GRIP1, RAC3, RIP140, and p300 mRNAs was observed in control uteri, and treatment with ER ligands did not alter coactivator mRNA levels. The data suggest that expression of these coactivator genes is not sensitive to estradiol or tamoxifen in the rat uterus. No cell type-specific pattern of expression was apparent in uterine sections from mature and immature rats; however, silver grains were more abundant in luminal and glandular epithelial cells compared with the stroma and myometrium, indicating that coactivator mRNA levels vary among the uterine compartments. Thus, to our knowledge, we show for the first time that there is constitutive expression of several uterine nuclear receptor coactivators in a physiological setting that remains insensitive to estrogenic regulation. Furthermore, we speculate that higher constitutive levels of coactivator expression in glandular and luminal epithelial cells may be associated with increased hormonal responsiveness by these uterine compartments.
Nephew
K P
KP
Medical Sciences, Indiana University School of Medicine, Bloomington, Indiana 47405-4401, USA. knephew@indiana.edu
Ray
S
S
Hlaing
M
M
Ahluwalia
A
A
Wu
S D
SD
Long
X
X
Hyder
S M
SM
Bigsby
R M
RM
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D050882:CREB-Binding Protein; D004958:Estradiol / Q000494:pharmacology; D020847:Estrogen Receptor Modulators / Q000494:pharmacology; D005260:Female; D015870:Gene Expression; D005786:Gene Expression Regulation / Q000187:drug effects; D051548:Histone Acetyltransferases; D009687:Nuclear Proteins / Q000235:genetics; D056920:Nuclear Receptor Coactivator 1; D051958:Nuclear Receptor Coactivator 2; D056921:Nuclear Receptor Coactivator 3; D000078723:Nuclear Receptor Interacting Protein 1; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013629:Tamoxifen / Q000494:pharmacology; D015534:Trans-Activators / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics*; D014599:Uterus / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; D020847:Estrogen Receptor Modulators; C498003:Ncoa2 protein, rat; D009687:Nuclear Proteins; D051958:Nuclear Receptor Coactivator 2; D000078723:Nuclear Receptor Interacting Protein 1; D012333:RNA, Messenger; D015534:Trans-Activators; D014157:Transcription Factors; D013629:Tamoxifen; D004958:Estradiol; D050882:CREB-Binding Protein; C494365:Crebbp protein, rat; D051548:Histone Acetyltransferases; D056920:Nuclear Receptor Coactivator 1; D056921:Nuclear Receptor Coactivator 3