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Ontogeny of the vitellogenic response to oestradiol and of the soluble nuclear oestrogen receptor in embryonic-chick liver.

ABSTRACT: A specific high-affinity oestradiol-binding protein was characterized in salt extracts of liver nuclei of the developing chick embryo. It is present in very small amounts at day 10 of development and is marginally stimulated by oestradiol injection into the yolk sac on day 8. Injection of oestradiol on day 10 evokes a substantial increase in the nuclear oestradiol-binding activity measured on day 12 of development. This oestradiol-binding protein has properties of sedimentation, hormone specificity and high-affinity binding very similar to those of the soluble nuclear receptor in hatched chicks. Livers from the 12-day embryos injected 48 h earlier with oestradiol do not synthesize vitellogenin, as judged by a specific immunochemical and electrophoretic assay for this oestrogen-induced protein. Traces of vitellogenin synthesis can be induced in 13-day-embryo liver, and a substantial response, equivalent to that in hatched chicks, is seen in liver from 15-day embryos injected on day 13. The development of the ability of oestradiol to increase the concentration of the soluble nuclear receptor appears to be one, but not the only, critical factor involved in the development of the ability of chick liver to synthesize vitellogenin.

SUBMITTER: Lazier CB

PROVIDER: S-EPMC1185894 | biostudies-other | 1978 Jul

REPOSITORIES: biostudies-other

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Interaction of the anti-oestrogen, nafoxidine hydrochloride, with the soluble nuclear oestradiol-binding protein in chick liver.

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| S-EPMC1164844 | biostudies-other

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Project description:Oestrogen-primed and withdrawn chicks were injected with oestradiol benzoate, progesterone, and/or the anti-oestrogens tamoxifen and 4-hydroxytamoxifen. Oestrogen receptors were studied in oviduct chromatin solubilized by mild digestion of purified nuclei with micrococcal nuclease. After a single injection of oestradiol benzoate, ultracentrifugation on sucrose gradients of chromatin extracts labelled with [3H]-oestradiol showed two peaks of oestradiol binding sites, sedimenting at 13--14 S and 7--8 S. After repeated injections of oestradiol benzoate, the 13--14 S peak increased more than the 7--8 S peak. After injection of anti-oestrogen alone or together with oestradiol benzoate, no [3H]oestradiol-binding or 4-hydroxy[3H]tamoxifen-binding peaks were detected in the chromatin. Injection of progesterone also produced an increase of the 13--14 S and 7--8 S chromatin oestradiol receptor. Progesterone receptor could only by detected in chromatin early after progesterone administration, and it sedimented in density gradients with the 12 S mononucleosome fraction. Tamoxifen injected together with progesterone gave higher levels of 13--14 S oestrogen binding sites than did progesterone alone. The presence of a 13--14 S peak of oestrogen binding sites in hormonal situations which promote a biological response in the chick oviduct, and the absence of this peak after administration of anti-oestrogens, suggest that this subfraction of chromatin contains elements involved in gene regulation.

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Synthesis of apoprotein B of very low density lipoprotein in embryonic-chick liver. Development of responsiveness of oestrogen.

Project description:The influence of exogenous oestrogen on the rate of synthesis of the apoprotein B of very-low-density lipoprotein by embryonic chick liver has been examined at various stages of development. Significant synthesis of apoprotein B was found in the absence of hormone treatment as early as day 6 of egg incubation. This basal level of apoprotein B synthesis varied from 2.5--6% of total protein synthesis. Embryos at day 10 or earlier treated with oestradiol exhibited no increase in the basal level of apoprotein B synthesis. Embryos at day 11 responded to oestradiol slightly and, from days 12 to 20, oestrogen treatment raised the relative rate of apoprotein B synthesis significantly above basal values: the maximal rate was about 16% of total protein synthesis. The anti-oestrogen tamoxifen citrate abolished the hormone-induced increase in apoprotein B synthesis and was not itself oestrogenic. The basal level of apoprotein B production was not sensitive to tamoxifen citrate, either in relatively early or in later stages of development. The basal level of apoprotein B synthesis, therefore, is oestrogen-independent and under developmental control distinct from the hormone-sensitive synthesis. The ontogeny of oestrogen-responsiveness of apoprotein B production appears to parallel the acquisition of the hepatic oestrogen-receptor system [Lazier (1978) Biochem. J. 174, 143--152].

| S-EPMC1162391 | biostudies-other

Dynamics of oestrogen-receptor distribution between the cytosol and nuclear fractions of immature rat uterus after oestradiol administration.

Project description:1. The nuclear-myofibrilar (800g pellet) fraction of the uterus from immature (22-23 days old) rats not exposed to oestrogen exhibits saturable binding of oestradiol. The nuclear binding capacity represents approximately 10% of that of the cytosol fraction (approx. 3.5 fmol/mug of DNA). The predominant part (0.3.5 fmol/mug of DNA) of the nuclear binind sites are present in the residual pellet after extraction with 0.5 M-KC1. 2. By using an exchange technique in vitro, determinations of the nuclear binding sites have been carried out after administration of 1 mug of oestradiol in vivo. Within 0.5h after the hormone injection, the concentration of nuclear bindng sites increased to approx. 0.4 fmol/mug of DNA in the 0.5 M-KC1-extractable fraction, and to approx. 1.2 fmol/mug of DNA in the residual fraction. Meanwhile the cytosol oestrogen-receptor concentration decreased to approx. 10% of its initial value. In the following period from 0.5 h after the oestradiol injection onwards, the concentration of nuclear oestrogen receptors decreased with halflife values of approx. 140 and 200 min for the KC1(0.5 M)-extractable and residual form respectively. At the same time, the cytosol receptor concentration increased to reach approx. 50% of the initial value by the 6h. This increase could not be blocked by cycloheximide. The initial concentration of cytosol receptor was restored approx. 11h after the injection and the increase during the 6-11h period was sensitive to cycloheximide inhibition, suggesting protein-synthesis-dependence of the process. 3. With the (more) physiological dose of oestradiol (0.1 mug), the decrease the cytosol receptor was only 50% by 4h and this was followed by a period (up to 12h after injection) during which the initial concentration was restored. During this period the increase of the receptor can be blocked by cycloheximide.

| S-EPMC1165351 | biostudies-other

Isolation and purification of a hen nuclear oestrogen receptor and its effect on transcription of chick chromatin.

Project description:An oestrogen receptor was isolated, characterized and purified from the nuclear fraction of the hen oviduct. The receptor sediments at 4.6 S on glycerol gradients, has an equilibrium dissociation constant (Kd) of 1.1 X 10(-10)M, an association constant (ka) of 1.4 X 10(-6) M-1.S-1, and a dissociation constant (kd) of 5 x 10(-5) s-1. The receptor chromatographed from DEAE-cellulose as a single peak at 0.15 M-KCl and was not retained by phosphocellulose. Polyacrylamide-gel electrophoresis of the receptor in the presence of sodium dodecyl sulphate demonstrated two subunits with apparent mol.wts. of 74000 and 80000. The overall purification achieved was 90000-fold by using a combination of cell fractionation, (NH4)2SO4 fractionation and affinity chromatography. This represents the first separation, isolation and purification of the highest-affinity binding component (Kd 10(-10)M) of two high-affinity oestrogen-binding proteins present in both chick and hen oviduct cytosol and nuclei. To examine directly the effect of the purified receptor on transcription a reconstituted cell-free system was used, which contained the receptor--oestradiol complex, Escherichia coli RNA polymerase, rifampicin and chromatin prepared from hormone-withdrawn chick tissue. The receptor-hormone complex at a concentration of 0.1 nM stimulated transcription of oviduct chromatin by promoting an increase of 14000 sites for RNA-chain initiation, which is similar to the number of additional sites measured in the oviducts of diethylstilboestrol-stimulated immature chicks [Tsai, Schwartz, Tsai & O'Malley (1975) J. Biol. Chem. 250, 5165-5174]. Oestradiol alone had no effect on transcription. Thus the data demonstrate that the purified nuclear oestradiol-receptor complex can regulate gene transcription in vitro in a manner similar to that observed in target cells in vivo.

| S-EPMC1161768 | biostudies-other

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