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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The appearance, epithelial and stromal cell distribution of estrogen receptors (ER) in normal mouse mammary gland were determined between 1 and 10 weeks of age using immunohistochemistry. The effect of ovariectomy and estrogen (E)-treatment on the distribution and concentration of ER-positive cells at various ages was also analyzed. These studies demonstrate that ER are present in both mammary epithelial and stromal cells before the mammary gland exhibits a proliferative response or increase in progesterone receptor concentration as a result of E-treatment. Furthermore, an analysis of E-treatment suggests that although ER are present at an early age, there may be additional factors that determine the nature and extent of E-responsiveness.
J Steroid Biochem Mol Biol 1992 Jul
PMID:The ontogeny and cellular distribution of estrogen receptors in normal mouse mammary gland. 163 22

Synergistic action of multiple steroid hormone response elements (HREs) has been proposed to be due to cooperative binding of receptors. We have studied the cooperativity of steroid hormone receptor binding to synergistic HREs in two natural genes. In the mouse mammary tumor virus long terminal repeat that contains four progesterone receptor binding sites, no cooperativity in receptor binding was observed between the single distal and the three proximal sites whereas a low level of cooperativity in receptor binding (about 2-fold) was found between the three proximal sites. This contrasted with the very strong synergism of these four HREs in stimulation of transcription. In the chicken vitellogenin II gene upstream sequences, an estrogen and a progestin response elements act synergistically. In this case again, no cooperativity of binding of the estrogen and progesterone receptors to their respective binding sites was observed. We therefore conclude that cooperative receptor binding may not always be required for synergistic action of multiple HREs.
Mol Cell Endocrinol 1991 Dec
PMID:In two genes, synergism of steroid hormone action is not mediated by cooperative binding of receptors to adjacent sites. 166 57

We have introduced the human estrogen receptor (ER) gene into HeLa cells, a human adenocarcinoma cell line of uterine origin, by infection. The ER cDNA was inserted into a retroviral vector (pMV7-ER) which also contains the neomycin resistance gene to allow for selection of stable infected clones. Northern analysis showed exogenous ER expression in stable clones. The ER protein expressed was about 66 kDa, similar to native MCF-7 ER, and binds with high affinity to estrogen (E2). We have also observed that addition of E2 at 10(-8) M inhibits the growth of the I-1 clone which expresses high levels of the ER (223 fmol/mg cytosol protein). The inhibitory effects of E2 directly correlate with the quantity of ER in the cells. E2-induced gene expression analysis showed that pS2 and progesterone receptor (PgR), genes induced in MCF-7 cells by E2, are not induced in the ER+ HeLa clones. However, c-myc expression was found to be decreased and may be responsible for the observed growth inhibition by E2.
Mol Cell Endocrinol 1991 Jun
PMID:Stable expression of the human estrogen receptor in HeLa cells by infection: effect of estrogen on cell proliferation and c-myc expression. 168 89

Using transient transfection assays, we showed that repression of the alpha-fetoprotein promoter by intact and deletion mutants of the progesterone receptor and by chimeric progesterone/glucocorticoid-estrogen receptors in the presence of their cognate hormones was closely correlated with their ability to bind to a progesterone/glucocorticoid-responsive element. This negative regulation was also observed in the presence of antihormones, providing evidence that receptor-antihormone complexes can bind to their responsive elements in vivo.
Mol Cell Biol 1990 Sep
PMID:Repression of the alpha-fetoprotein gene promoter by progesterone and chimeric receptors in the presence of hormones and antihormones. 169 36

The monoclonal antibody AB-52 has high affinity and specificity for the two natural human progesterone receptor forms, receptor A (hPRA) and receptor B (hPRB), but it does not bind the PR of chick, mice, rats or rabbits. We have used a novel method to map its epitope. Based on a series of site-directed mutants of hPRA, together with immunoblotting, DNA gel mobility shift and antibody super shift assays, we have mapped the epitope of AB-52 to a 17 amino acid sequence lying between Val221 and Leu237 of the 933 amino acid hPRB protein. This N-terminal sequence is common to both hPRB and hPRA but is missing in chick PR and differs extensively from mouse PR. No anti-rabbit PR antibodies map to the homologous rabbit PR sequence which differs from hPR by four amino acids, suggesting that one or more of these four amino acids form a critical subset of residues in hPR that define the human specificity of AB-52. Knowledge of the AB-52 epitope is useful in structural analysis of PR, and in competition studies. Additionally, this 17 amino acid peptide whose antigenicity would not be predicted from computer analysis, should be useful for generating additional hPR specific antibodies.
J Steroid Biochem Mol Biol 1991 Nov
PMID:Epitope mapping of the anti-human progesterone receptor monoclonal antibody, AB-52. 172 Mar 26

We have examined the ability of estradiol (E2) to regulate the expression of three mRNAs [for pS2, progesterone receptor (PR), and estrogen receptor (ER)], known to be under E2 regulation in the parental E2 growth-responsive MCF-7 cells, in an E2 growth-independent MCF-7 K3), previously isolated from the parental estrogen-dependent MCF-7 K1 human breast cancer cells after long term growth in vitro in the absence of estrogen, acquired estrogen-independent growth in vitro as well as the ability to form tumors in nude mice in vivo without estrogen. We find that the content of pS2 mRNA and the transcription rate of the pS2 gene, while being markedly increased by E2 in MCF-7 K1 cells, are no longer stimulated by E2 in this subline, although protein kinase activators tremendously increase (greater than 10-fold) pS2 mRNA in both K1 and K3 cells. In fact, basal pS2 mRNA levels are elevated 2.8 +/- 0.4-fold in MCF-7 K3 cells, and E2 evokes a concentration-dependent suppression of the pS2 mRNA level. In contrast, PR mRNA in the K3 subline, as in the parental K1 cells, is still up-regulated by E2, and ER mRAN content and the ER mRNA transcription rate are still down-regulated by E2 and show normal E2 dose-response relationships, implying that the ER in this subline is functional. These results demonstrate that the progression to estrogen-independent growth in K3 cells is accompanied by a change in the regulation of some estrogen-induced genes by estrogen. While PR and ER retain normal patterns of regulation by E2, the pS2 gene in the estrogen growth-independent K3 subline is differentially affected and is no longer stimulated by E2. Our data suggest that this altered regulation of the pS2 gene is probably not caused by a defect of the ER or ER regulation in this subline.
Mol Endocrinol 1991 Sep
PMID:Differential regulation of gene expression by estrogen in estrogen growth-independent and -dependent MCF-7 human breast cancer cell sublines. 172 71

Expression of prostate-specific antigen (PA) mRNA was tested at various time periods after incubation of the human prostate tumor cell line LNCaP with the synthetic androgen R1881. Androgen-stimulated expression was observed within 6 h after addition of R1881 to the cells. Run-on experiments with nuclei isolated from LNCaP cells showed that expression of the PA gene could be regulated by R1881 on the level of transcription. DNase I footprints of the promoter region of the PA gene (-320 to +12) with nuclear protein extracts from LNCaP cells showed at least four protected regions. The protected areas include the TATA-box, a GC-box sequence, and a sequence AGAACAgcaAGTGCT at position -170 to -156, which closely resembles the reverse complement of the consensus sequence GGTACAnnnTGTTCT for binding of the glucocorticoid receptor and the progesterone receptor. Fragments of the PA promoter region were cloned in front of the chloramphenicol acetyltransferase (CAT) reporter gene and cotransfected with an androgen receptor expression plasmid into COS cells in a transient expression assay. CAT activity of COS cells grown in the presence of 1 nM R1881 was compared to untreated controls. A 110-fold induction of CAT activity was found if a -1600 to +12 PA promoter fragment was used in the construct. By further deletion mapping of the PA promoter a minimal region (-320 to -155) was identified as being essential for androgen-regulated gene expression. Mutation of the sequence AGAACAgcaAGTGCT (at -170 to -156) to AAAAAAgcaAGTGCT almost completely abolished androgen inducibility of the reporter gene constructs. One or more copies of the sequence AGAACAgcaAGTGCT cloned in front of a thymidine kinase promoter-CAT reporter gene confers androgen regulation to the reporter gene. These findings provide strong evidence for transcription regulation of the PA gene by androgens via the sequence AGAACAgcaAGTGCT. Interestingly, in addition to the AGAACAgcaAGTGCT element, an upstream region (-539 to -320) is needed for optimal androgen inducibility of the PA promoter.
Mol Endocrinol 1991 Dec
PMID:The promoter of the prostate-specific antigen gene contains a functional androgen responsive element. 172 87

We have reported previously that chicken progesterone receptor (PR) is phosphorylated in vivo in response to progesterone administration. Three phosphorylation sites have been reported, two of which show increased phosphorylation in response to hormone and one which is phosphorylated only in response to hormone administration. We found previously that PR lacking the hormone-dependent phosphorylation is active in an in vitro transcription assay. Since the source of general transcription factors is a HeLa nuclear extract which contains many kinases, we have analyzed the receptor for phosphorylation during the in vitro transcription assay. We report here that the receptor is rapidly and efficiently phosphorylated on new sites, causing a change in receptor mobility on sodium dodecyl sulfate-gels. This phosphorylation is strictly dependent upon the presence of double stranded DNA. A DNA-activated protein kinase with similar properties has been isolated previously from HeLa cell nuclei. We find that phosphorylation of PR with this purified enzyme mimics the phosphorylation observed in the transcription assay. These data suggest that a previously undetected additional series of DNA-dependent phosphorylations may be required for activation of the PR.
Mol Endocrinol 1992 Jan
PMID:Chicken progesterone receptor is phosphorylated by a DNA-dependent protein kinase during in vitro transcription assays. 173 74

Transforming growth factor-beta (TGF beta) is a potent growth inhibitor in most epithelial cells. We evaluated the effects of norethindrone (which in combination with estrogen is commonly used in oral contraceptives) and other progestins [medioxyprogesterone acetate (MPA) and R5020, which are not used in oral contraceptives] on cell growth and the expression of TGF beta 1, TGF beta 2, and TGF beta 3 mRNAs in MCF-7 human breast cancer cells. Growth of MCF-7 cells was stimulated by norethindrone (10(-8)-10(-5) M), with maximal growth stimulation at 10(-7) M norethindrone after 7 days of treatment. However, the growth of MCF-7 cells was not affected by MPA (10(-8) M) or R5020 (10(-8) M). Treatment with the antiestrogen 4-hydroxytamoxifen at a concentration of 10(-7) M blocked the growth stimulation induced by norethindrone. The norethindrone-induced growth stimulation was accompanied by a dramatic decrease in TGF beta 2 and TGF beta 3 mRNA levels, whereas the level of TGF beta 1 mRNA was not affected by any of the compounds tested. In addition, treatment with MPA or R5020 did not affect TGF beta 2 and TGF beta 3 mRNA levels. The inhibitory effect of norethindrone on TGF beta 2 and TGF beta 3 mRNA levels could be blocked by the addition of 10(-7) M 4-hydroxytamoxifen. Norethindrone as well as estradiol decreased estrogen receptor mRNA levels and increased progesterone receptor mRNA levels. This is the first report which demonstrates that norethindrone stimulates estrogen-responsive human breast cancer cell growth and inhibits the expression of TGF beta 2 and TGF beta 3 mRNAs. These results suggest that the differential regulation of TGF beta expression by norethindrone may be at least partly responsible for the growth stimulation induced by norethindrone. Thus, the norethindrone component of some oral contraceptives may be sufficiently estrogenic to facilitate the development of breast cancer.
Mol Endocrinol 1991 Aug
PMID:Growth stimulation and differential regulation of transforming growth factor-beta 1 (TGF beta 1), TGF beta 2, and TGF beta 3 messenger RNA levels by norethindrone in MCF-7 human breast cancer cells. 183 33

The ovarian steroid progesterone affects reproductive physiology by regulating the expression of specific genes in target tissues. In an attempt to address the question of whether the ovary itself is a target tissue for progesterone action, we have examined the localization and regulation of progesterone receptor (PR) mRNA in the rat ovary. We used the polymerase chain reaction to clone the steroid-binding domain of the rat PR from uterine cDNA and used this as a probe to isolate a larger cDNA from a rat placental cDNA library. We used RNA filter hybridization, a quantitative reverse transcription-polymerase chain reaction amplification assay, and in situ hybridization to detect PR mRNA in the rat ovary. Expression of the PR gene was initially studied in an immature animal model; 23-day-old rats were treated with either PMSG or PMSG followed by hCG. We found little or no PR mRNA in the ovaries of control or PMSG-treated animals; however, the mRNA was highly expressed in the granulosa cells of large follicles in the ovaries of animals treated with PMSG followed by hCG. Other cell types, including thecal and interstitial cells, did not express detectable levels of PR mRNA. The PR mRNA was induced more than 20-fold in the immature ovary 5 h after hCG administration and was down-regulated to near-basal levels by 12 h after hCG administration. In a subsequent series of experiments, we examined PR gene expression in adult rats during the estrous cycle. The expression of PR mRNA was transient and was tightly coupled to the preovulatory LH surge on proestrous evening. PR mRNA was localized to the granulosa cells of mature ovarian follicles during the estrous cycle. In cycling animals treated with pentobarbital to block the preovulatory LH surge, no induction of PR mRNA on proestrous evening was observed. This transient, hormonally regulated, and cell-specific expression of the PR gene in the rat ovary strongly suggests an important intraovarian function for progesterone during the rat reproductive cycle.
Mol Endocrinol 1991 Jul
PMID:Transient expression of progesterone receptor messenger RNA in ovarian granulosa cells after the preovulatory luteinizing hormone surge. 184 Jun 36


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