Nuclear Poly(A) Polymerase Activities in the Rabbit Uterus. Regulation by Progesterone Administration and Relation to the Activities of RNA Polymerases and Chromatin Template (original) (raw)
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Archives of Biological Sciences, 2007
The aim of this study was to examine the effects of estradiol (E2) on activity of RNA polymerase I and RNA polymerase II in uterine nuclei of ovariectomized (OVX) female rats. The obtained results show that estrogen-receptor (E-R) complexes in 30 min induced an increase of polymerase II activity. A second increase of polymerase II activity was observed after 3 h-incubation of nuclei with the E-R complex formed in the cytosol fraction. However, activity of polymerase I was increased 2 h after the start of incubation, with highest activity detected at 3 h in nuclei incubated with E-R complexes. On the contrary, no stimulatory effect on either polymerase I or polymerase II activity was observed in nuclei incubated with E2 alone. These results indicate that E2 stimulates the cytosolic estrogen receptor (ER), which in turn causes uterotrophic responses in OVX rats. In addition, they suggest that in order to provoke uterotrophic responses E-R complexes formed in the cytosol need to be retained in the nucleus for a longer period of time.
Interaction of activated estradiol-receptor complex and chromatin in isolated uterine nuclei
European journal of cancer, 1973
Exposure at 4°C and 22°C of purified uterine nuclei to uterine cytosol preincubated with estradiol-17fl causes a significant increase in their ability to bind 3H-actinomycin D. This increase reaches almost its maximum within 15 minutes following exposure. It does not occur at 4°C when the nuclei are exposed to cytosol added with estradiol-17~ immediately before mixing rather than preincubated with it. It does not occur either when nuclei are exposed to any of the following solutions: cytosol preincubated with estrone, cytosol alone, buffer added with estradiol-17fl or estrone, or buffer alone. Exposure of nuclei from uterus and from diaphragm to cytosols from these tissues increases the nuclear binding of 3H-actinomycin D only when uterine nuclei are exposed to uterine cytosol.
Early effect of estrogen on chromatin ultrastructure in endometrial nuclei
Molecular and Cellular Endocrinology, 1980
The effect of estradiol on chromatin ultrastructure in interphase nuclei was studied in immature rat and lamb endometrium. Physiological doses of estradiol within the first hour transformed the condensed chromatin into dispersed chromatin both in vivo and in vitro. These ultrastructural modifications were specifically induced by hormones translocating the estrogen receptor to the nucleus of estrogen-responsive tissues. Conversely, the antiestrogen tamoxifen gave a hypercondensation of chromatin. The addition of actinomycin D, cordycepin or o-amanitin, but not of cycloheximide, prevented the effect of estradiol both on the ultrastructural change and on [ 3H]uridine incorporation, suggesting that chromatin decondensation was closely related to transcriptional activity. These results indicate that in endometrium, estrogen rapidly provokes a large and extended modification of chromatin ultrastructure, which suggest a general effect on chromatin function rather than a selective activation of a limited number of genes.
Messenger RNA for progesterone receptor isoforms in the late-gestation rat uterus
American Journal of Physiology-Endocrinology and Metabolism, 2002
The progesterone receptor (PR) has three isoforms, PR-A, PR-B, and PR-C, which have different physiological effects. PR-A may inhibit PR-B-mediated transcription. Parturition requires withdrawal of progesterone (P4). This could occur through decreased P4concentrations and/or a change in PR isoforms to diminish the effect of P4. We measured mRNA for PR isoforms in rat uterine tissues through late gestation and investigated the effects of antagonists to estrogen (tamoxifen) and P4(RU-486). Two specific probes were used for ribonuclease protection assays; one (PR-total) measured PR-A, PR-B, and PR-C, and the other recognized only PR-B. PR-total mRNA increased significantly through late gestation, whereas PR-B was unchanged. The ratio of PR-total to PR-B peaked on the day before parturition. Tamoxifen delayed parturition and inhibited the increase in PR-total without affecting PR-B mRNA. RU-486 caused early parturition associated with increased PR-total mRNA, with no change in PR-B. We ...
The Biochemical journal, 1980
Polyribosome formation and the characteristics of polyribosomal poly(A)-containing RNA from uteri of ovariectomized rats responding to a single dose of oestradiol-17 beta was investigated. The mean proportion of polyribosomes in the atrophic uterus was 65%. In response to 10 micrograms of oestradiol-17 beta/100 g body mass, the amount of polyribosomes increased to 88% 24 h after stimulation. Thereafter the proportion of polyribosomes decreased to a value of 48% at 72h. The pattern of amino acid incorporation in oocytes from Xenopus laevis injected with these polyribosomes was similar to the changes in polyribosome formation and degradation. The polyribosomal poly(A)-containing RNA from the controls consisted of a heterogeneous population of RNA with sedimentation values between 5S and 25S. The hormone stimulation resulted in an increase in both the amount and the size (13S to 35S) of the RNA.
European Journal of Biochemistry, 1980
Endometrical nuclei, prepared from rabbits subjected to different hormonal treatments, were used for the cell-free synthesis of RNA. Optimal conditions for the incorporation of [3H]UMP into RNA are described, leading to the synthesis of relatively undegraded RNA molecules. Under these conditions there is virtually no initiation of new RNA chains in vitro, and RNA chain elongation is inhibited up to 6004 by low concentrations of a-amanitin and up to 90% by actinomycin D. The synthesis of RNA is slightly inhibited in the presence of Hg-CTP and monothioglycerol, but newly synthesized mercurated RNA can be efficiently separated from endogenous RNA upon chromatography on sulfhydryl-Sepharose under stringent conditions. The RNA synthesized in vitro by endometrial nuclei from pseudopregnant rabbits contains RNA sequences transcribed from the uteroglobin gene, as demonstrated by hybridization to an excess of purified preuteroglobin cDNA. In endometrial cells from pseudopregnant animals the number of RNA polymerase I1 molecules transcribing the uteroglobin gene is 12-fold higher than in control animals, demonstrating that at least part of the hormonally induced accumulation of preuteroglobin mRNA is due to an increased rate of transcription of the uteroglobin gene.
An analysis of the binding of the chick oviduct progesterone-receptor to chromatin
Biochimica et Biophysica Acta (BBA) - General Subjects, 1975
The binding of progesterone-receptor complexes to chromatin from target and nontarget tissues was studied in vitro. Chromatin from both ta~;et and nontarget tissues responds in a similar manner to saly and cofactors and has the same K D (approx. 3 • 10-9 M) for the progesterone-receptor complex. The only observed difference in the binding of the progesterone-receptor complex to target and nontarget chromatins is the difference in total number of acceptor sites. Oviduct chromatin has approx. 1300 sites/pg DNA, spleen chromatin has approx. 840 sites/pg DNA, and erythrocyte chromatin has about 330 sites/pg DNA. The K n and number of acceptor sites for progesterone-receptor complex binding to oviduct chromatin remains the same even after extensive purification of the progesterone-receptor complex. Activation of cytosol labeled with [3H]progesterone by preincubation at 25°C, analogous to that required for maximal nuclear binding, occurs if the binding studies to chromatin are performed in 0.025 M salt. The absence of an observable temperature effect when the studies are performed at 0.15 M salt is due to the activation of the receptor by salt. The dissociation of the progesterone-receptor complex from chromatin exhibits a single dissociation rate and the initial event is the appearance of free progesterone rather than a progesterone-receptor complex. Lastly, the treatment of chromatin with an antibody prepared against either single-stranded DNA or double-stranded DNA does not alter the extent of binding of the progesterone-receptor complex. Similarly, pretreatment of chromatin with a single-stranded nuclease does not inhibit the capacity of chromatin to bind the hormone-receptor complex.
Biochemical Journal, 1969
1. After treatment of immature rats with diethylstilboestrol, the wet weight and RNA content of uterine tissue increased rapidly, reaching a peak at 40hr. After an initial lag of a few hours, the acid-soluble ribose and protein contents also rose to maxima at 40hr. No increase in DNA content occurred until at least 24hr. after treatment. 2. The RNA from immature rat uterus isolated at various times up to 6hr. after administration of oestradiol-17β was labelled by injecting [3H]uridine and [3H]guanosine intraperitoneally 30min. before the animals were killed. It was fractionated on columns of kieselguhr coated with methylated serum albumin and the radioactivity in fractions corresponding to transfer RNA, 7s RNA, ribosomal RNA, Q1-RNA, Q2-RNA and DNA-like RNA was determined. 3. The radioactivity of the whole RNA increased steadily for 6hr. after hormone treatment. The earliest changes occurred in the Q1-RNA (ribosomal RNA precursor), whereas at longer time-intervals the radioactivity ...
Synthesis of oviduct nuclear and chromatin proteins during steroid induced differentiation
Cell differentiation, 1975
Synthesis of nuclear histones and nonhistones was studied in chick oviduct during stimulation with estrogen and progesterone. In estrogen primed chicks, as compared to progesterone primed chicks, oviduct nonhistones are enriched in polypeptides of 50,000 daltons and larger. A secondary stimulation with the steroids increases the amino acid incorporation into histones and nonhistones two to six fold. Injection with estrogen induces preferential labelling of nonhistone polypeptides at 50,000 to 60,000 daltons independent of the kind of primary stimulation. A secondary injection with progesterone increases the amounts of highly labelled polypeptides with a molecular weight of over 70,000 daltons.