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V B Rozen

Publications and source records attributed to V B Rozen.

At least 37 records · Page 2Linked to original sources
PubMed1986

[A special estrogen-binding protein of the liver: additional data on the structural determinants of androgenic ligands].

The relative competitive activity of some androstane derivatives was determined by 50% inhibition of [3H]estradiol binding to an unusual estrogen-binding protein (UEBP) of male rat liver. It was shown that: i) the bulk of energy of the steroid-protein complex is derived from hydrophobic interactions; ii) the authentic ability to form specific complexes with UEBP at androgene concentrations close to physiological ones, is determined by 17 beta-hydroxyl and is enhanced by the 3 alpha- or 2 alpha-oxy-group; iii) 3- and 17-keto groups inhibit androgene interaction with UEBP; iiii) the cis-conjunction of rings A and B in the androgen molecule does not block steroid binding to the protein. These data specify significantly the mechanism of androgene interaction with UEBP and shed additional light on the physiological role of this protein.

Androstanes↗
PubMed1986

[Effect of antibodies against the specific estrogen-binding protein in the rat liver on the hormone-binding activity of this protein and steroid hormone receptors].

The effects of rabbit polyclonal antibodies (AB) against an unusual estrogen-binding protein (UEBP) isolated from rat liver by immunoadsorption on the interaction of [3H]estradiol with UEBP, estrogen receptors of uterus and other tissues, of [3H]dihydroxytestosterone with prostate androgen receptors, of [3H]progesterone with uterine progesterone receptors and of [3H]dexamethazone with rat thymus glucocorticoid receptors were investigated. It was shown that preincubation of cytosol of the above tissues with AB decreases the ability of UEBP, estrogen and androgen receptors to bind the corresponding ligands. The hormone-binding activity of progesterone and glucocorticoid receptors in the presence of AB remains thereby unchanged. The binding activity of UEBP in the presence of ABUEBP diminishes due to the decrease in the concentration of protein binding sites, whereas that of estrogen and androgen receptors decreases due to the diminution of affinity for their ligands which, in turn, is the result of reduction of the association rate constant. A cross influence of AB on the activity of uterine estrogen receptors of rabbit, guinea pig and mouse was observed. It was assumed that the structure of UEBP and sex steroid receptors has some similar elements.

Androgens↗
PubMed1986

[Physico-chemical properties and amino acid composition of a highly purified preparation of a specific estrogen-binding protein of the rat liver].

The structure and properties of an unusual estrogen-binding protein (UEBP) from male rat liver that was purified by affinity adsorption chromatography was studied. A high degree of purity of UEBP (greater than 99%) associated with appreciable microheterogeneity was demonstrated. The latter seems to be due to partial proteolysis of the protein at the N-end in the course of the isolation procedure. The purified UEBP molecules have the following characteristics: Mr = 31 000 (data from SDS-PAAG electrophoresis), sedimentation coefficient 3.75 S, Stockes'radius 25.6 A, friction coefficient ratio 1.11. The protein absorbance maximum in the UV region lies at 276 nm; extinction coefficient--26, alpha-helix content is 25-30%. The value of equilibrium association constant for estradiol is 5 X 10(7) M-1. Estriol (greater than 100%) and, in a weaker degree, estrone and testosterone (approximately 10%) compete for the binding sites with [3H]estradiol; androsterone has no competitive effect. The amino acid composition of UEBP was determined. The protein was shown to possess a great number of residues carrying hydrophobic side groups (34.4%) and more acidic amino acids over basic ones as well as a low content of cystein, threonine and histidine.

Amino Acids↗
PubMed1985

The unusual estrogen-binding protein (UEBP) of rat liver: the role of sex steroids and hypophysis in its regulation.

The number of estradiol (E2) binding sites of rat liver unusual estrogen-binding protein (NUEBP) was measured, using a novel modification of the quantitative method of specific UEBP determination. In liver cytosol of mature male and female rats, NUEBP amounted to 6.83 +/- 0.49 and less than 0.05 pmol/mg protein, respectively. Neonatal administration of testosterone-propionate (TP) and TP injections at later periods of ontogenesis increased NUEBP in female rat liver in a similar fashion. The elevated NUEBP was found in the liver of mature ovariectomized females 30 days after cessation of TP injections. Hypophysectomy (but not adrenalectomy or thyroidectomy) prevented TP induction of elevated NUEBP in pubertal females. E2 injections reversibly decreased NUEBP in the liver of all animals under study except of hypophysectomized males. A stimulating regulatory effect of TP on NUEBP in male rat liver was observed only in the case of endogenous androgen deficiency and low NUEBP. TP prevented the E2-dependent decrease of NUEBP upon their simultaneous injections and increased the E2-reduced NUEBP when injected after E2. Hypophysectomy led to a decrease of NUEBP in pubertal males but only slightly affected that in castrated animals. After TP injections to hypophysectomized males, NUEBP returned to a level next to the initial one. It was concluded that estrogen-androgen regulation of the UEBP level led to the maintenance of sex differences in the UEBP content.

Animals↗
PubMed1985

[Effect of estradiol and other endocrine factors on the level and dynamics of estrogen receptors in the liver cells of rats].

The authors studied the effects of different doses of estradiol (E2) on the level of estrogen receptors (ER) in female rat hepatocytes and the dynamics of ER distribution between the cytosol and nuclear cell fractions and compared the changes in the ER level in the liver in different endocrine states of the body. It was shown that the ER level in hepatocytes was far lower than in uterine cells and drastically increased during puberation and after ovariectomy. It was also found that the ER level in hepatocytes was dependent on pituitary functions. After a single injection of E2, the ER level in cytosol descended and that in the nucleus rose. The degree of ER reduction in cytosol and increase in the nucleus correlated with the dose of E2. The dynamics of intercombined changes in the levels of cytosol and nuclear ER was studied at different time intervals following the injection of different doses of the hormone. Some essential organ-specific features of E2 reception in the liver were revealed. Different mechanisms of the control of ER content in the liver and uterus are postulated.

Animals↗
PubMed1985

[Unusual estrogen-binding liver protein in rats and the metabolism of sex steroids].

A study was made of the effect of a highly purified preparation of an unusual estrogen-binding protein (UEBP) of rat liver on 3H-estradiol (3H-E2) and 3H-testosterone (3H-T) metabolism by female rat liver homogenates. The UEBP decreased the rate of metabolic conversions of 3H-E2 and 3H-T in a dose-dependent and specific manner. The effectiveness of the inhibitory action of the UEBP declined with increase of metabolic activities of homogenate enzymes. The effects of the UEBP were reduced fully or partly by the ligands specifically binding to the UEBP, estrone (E1), and estriol (E3) respectively. The latter fact was used to demonstrate the effectiveness of the endogenous male rat liver homogenate UEBP in the control of 3H-E2 metabolism. The UEBP did not exhibit any oxidoreductase activity on the use of 3H-E1, 3H-E2, 3H-E2, 3H-T and 3H-androstenedione with NAD+, NADH, NADP+, and NADPH as cofactors. These data present the first direct experimental evidence of the regulatory function of the UEBP in the time course of changes in sex steroids.

Animals↗
PubMed1985

[Role of sex steroids and the pituitary in regulating the level of a specific estrogen-binding protein in rat liver].

The effects of androgens (A), estrogens (E) and hypophysectomy on the content of an unusual rat liver estrogen-binding protein (UEBP) were studied by the differential quantitative method of the UEBP content measurement. The UEBP content was shown to increase during maturation of male rats. After A injections the UEBP content was high only in the liver of prepubertal but not of mature or immature males. Castration or hypophysectomy of mature males equally caused a decrease in the UEBP content in mature males whereas subsequent administration of A made it completely return to normal. Hypophysectomy of castrated males did not alter the UEBP content. A single injection of E provoked an appreciable reduction in the UEBP level after several days. Administration of A interfered with the inhibitory action of E after simultaneous injection of A and E and recovered the E-induced lowering of the UEBP content upon administration of A following E. Hypophysectomy of castrated males did not affect significantly the UEBP level. The UEBP content was insensitive to the direct action of pituitary factors. The pituitary is necessary for the realization of the effects of E alone but not A. It is suggested that the regulatory role of A consists in the maintenance of the constant optimal UEBP level in rat liver.

Animals↗
PubMed1985

[A special estrogen-binding protein in the rat liver: the effect of nuclear accumulation of estradiol-receptor complexes in vitro].

The accumulation of [3H]estradiol-receptor complexes by liver nuclei after preliminary incubation of the hormone with rat liver cytosol was studied. It was demonstrated that addition to female rat liver cytosol of a purified preparation of the unusual estrogen-binding protein (UEBP) from male rat liver causes a dose-dependent inhibition of subsequent accumulation of specifically bound [3H]estradiol in the nuclei. Addition to male rat liver cytosol of 1.5 microM 2 alpha-hydroxytestosterone, testosterone, 1-dehydrotestosterone, 5 alpha-androstane-3 alpha, 17 beta-diol and 5 alpha-dihydrotestosterone, i. e. compounds possessing marked affinity for UEBP, resulted in a 2-5-fold increase of the subsequent nuclear accumulation of estrogen-receptor complexes. The use of UEBP-deficient female rat liver cytosol revealed that the afore-mentioned steroids are ineffective with respect to estrogen reception. It is concluded that UEBP of male rat liver is capable of modulating estrogen reception.

Animals↗
PubMed1984

[Effect of estradiol and a series of other endocrine factors on the angiotensinogen level in rat blood plasma].

The effects of estradiol (E2) and some other endocrine factors on rat plasma angiotensinogen (AG) have been studied. AG was determined by RIA. Both single and multiple injections of E2 to female rats were shown to cause a dose-dependent increase in AG in the blood. The effect of E2 was inhibited by cycloheximide. Multiple injections of E2 to male rats caused the same hepatic AG synthesis induction as those to female rats. Unlike E2, long-term treatment with large doses of testosterone propionate did not affect AG synthesis. AG levels in blood plasma of ovariectomized and immature female rats did not differ from those seen in mature intact rats. However, immature females were insensitive to the stimulant effect of the pharmacological doses of E2. Drastic reduction in hepatocyte sensitivity of the stimulant effect of E2 was seen in hypophysectomized female rats as well. Treatment of hypophysectomized animals with human GH, which did not affect AG levels per se, caused an almost complete recovery of hepatocyte ability to react by increasing AG synthesis in response to E2 injection. The possible role of different hormonal and genetic hepatotrophic factors in hepatocyte reactivity to the stimulant effect of E2 on AG synthesis is discussed.

Angiotensinogen↗
PubMed1983

The unusual estrogen-binding protein (UEBP) of male rat liver: structural determinants of ligands.

The unusual estrogen-binding protein (UEBP) found in a male rat liver is a sex dependent protein which differs from other known receptor and transport proteins by the high lability of its complexes with estradiol (E2) and also the unique specificity of affinity for hormones. In this work values of relative binding affinity (RBA) of the UEBP for 57 steroids and their analogs were determined. The affinity of steroids was characterised by the amount of the unlabeled compound needed for 50% inhibition of [3H]-E2 binding with the UEBP. A number of derivatives of estrane and androstane possess an ability to interact with this protein, in contrast to the derivatives of pregnane, stilbene and triphenylethane. Characterized by RBA values, natural steroids are found to have the following order: estriol larger than or equal to E2 greater than 16 alpha-hydroxyestrone = 2 alpha-hydroxytestosterone greater than 16-epiestriol greater than or equal to estetrol greater than or equal to 17-epiestriol greater than or equal to 2-methoxyestradiol greater than or equal to 5 alpha-androstane-3 alpha,17 beta-diol greater than or equal to estrone greater than testosterone greater than or equal to 2 beta-hydroxytestosterone greater than 5 alpha-dihydrotestosterone. Affinity of estrogens and androgens for the UEBP diminishes abruptly after removal of 3- and 17-hydroxy groups, masking of these by ether bonds or changing of 17 beta-hydroxyl to 17 alpha. All the investigated 17 oxo-C19-steroids, 5 beta-derivatives of testosterone, its 6 beta- and 16 alpha-hydroxy metabolites as well as 5 alpha-androstane-3 beta,17 beta-diol and 19-nortestosterone exhibit no essential affinity for the protein. On the basis of the results obtained it is suggested that the binding sites for estrogens and androgens in the UEBP molecule overlap but do not completely coincide.

Androgens↗
PubMed1983

Interaction of purified rat liver glucocorticoid-receptor complexes with polynucleotides: strong base composition dependence.

The binding of 10(3)-fold purified rat liver glucocorticoid receptors to natural and synthetic polynucleotides has been studied. The receptors may bind to RNA as well as to DNA. The binding effectiveness of nucleic acids is strongly base composition dependent, with natural DNAs (double-stranded or denatured) greater than E. coli rRNA greater than poly(dA).poly(dT) greater than or equal to poly d(A,T,G)7 greater than or equal to poly(U) greater than poly(A).poly(U) greater than poly(A) approximately poly(C). The equilibrium (apparent) constants of receptor binding to a number of polynucleotides were calculated by a method proposed.

Animals↗
PubMed1982

[Comparative study of the interaction between different forms of estrogen receptors and cell nuclei].

A comparative in vitro study of interaction of estradiol (E2) complexes with different forms of cytosol estrogen receptors (ER) from rat liver, kidney and uterus, and cell nuclei was carried out. It was shown that complexes of E2 with ER of whole liver and kidney cytosol of female rats as well as complexes of E2 with forms I and II of liver ER separated from one another and partially purified can be translocated into cell nuclei, similar to the estrogen-receptor complexes (ERC) of uterine cytosol. ERC, which contain an unusual estrogen-binding protein of male rat liver cytosol, do not bind to the nuclei in vitro. The translocation into the nuclei of high molecular weight ERC from liver and uterus has some common features, e. g. the necessity of activation by various factors, similar kinetics, absence of marked organ specificity, non-saturation of nuclear binding sites for ERC, etc. In terms of these criteria (with the exception of kinetic patterns) the translocation of forms I and II of female rat liver ER appears to be identical. The kinetic patterns and the level of translocation into the nuclei and the binding to DNA-cellulose of forms I and II of liver ER at low ionic strength reveal some differences, i. e. form II is characterized by faster kinetics, but by a lower level of interaction with the nuclei and DNA-cellulose. These differences disappear as the ionic strength of solution rises. The fast kinetics of ERC translocation into the nuclei at low ionic strength is also typical for kidney cytosol ER which are similar to those of form II of liver ER. The data obtained suggest that various forms of ER are involved in initiation of a broad spectrum of hormonal effects of Er both in the cells of different tissues and in homologous cells of the same tissue.

Animals↗
PubMed1982

[Hormonal specificity of the affinity of specific estrogen-binding protein in the rat liver].

The ability of 57 steroids and their analogs to compete with 3H-estradiol for binding sites of an unusual estrogen-binding protein (UEBP) of the male rat liver was studied. The magnitudes of the equilibrium constants of association of 3H-estradiol, 3H-estriol, and 3H-5 alpha-androstane-3 alpha, 17 beta-diol with the UEBP were measured. It was shown that the derivatives of estrane and androstane, in contrast to those of pregnane, stilbene and triphenylethane, can effectively interact with the UEBP. The ability of estrogens and androgens to interact with the UEBP primarily depends on oxygen functions of the A and D rings and on general conformation of the steroid molecule. It is suggested that there are 2 subcenters for the steroid A and D rings both at the estrogen and androgen sites of the UEBP molecule. These subcenters for the two types of sex steroids either do not coincide or coincident are only subcenters for the ligand A rings.

Androgens↗
PubMed1981

[Gonadal endocrine function indicators during initial stages of postnatal ontogenesis of the female sable].

By means of radioimmunoassay, 17 beta-estradiol-, androgen- (testosterone and dihydrotestosterone) and progesterone contents were determined in the peripheral blood of the female sables, aged 2 to 27 months, during postnatal ontogenesis initial stage. Under the action of seasonal factors steroid level was sharply decreased in the animals of the all ages within the autumnal period, whereas the gonadal function activation lowered over a period of February and March, when "the spring animation" of wild stables is seen. An increase in the sex hormone level was more pronounced in females over one year old. The compared concentrations of hormones, studied in the 5-months' females (the growth stopping). 14 to 17-months' animals (the 1st year reproductive period) and 27-months' stables (the 2nd year reproductive period) were close to those of 17 beta-estradiol and progesterone contents in fertile animals. It is suggested that the sexual system of the 5-months' females is ready for the reproductive processes but their secretory activity is sharply reduced, probably under the seasonal factor influence.

Aging↗
PubMed1981

[Cytoplasm to nucleus translocation patterns of different forms of hepatic estrogen receptors].

Interaction between cell nuclei and the complexes of estradiol (E2) with uterine cytosol estrogen receptors (ER) or with different forms of female and male rat liver cytosol ER was studied and compared. The complexes of E2 with forms I and II of liver ER are capable to translocate to the cell nuclei similarly to E2 receptor complexes of the uterus. The complexes of E2 with an unusual male rat liver estrogen-binding protein do not bind to the nuclei. The processes of translocation of the complexes of E2 with form I of liver ER and uterine receptors have some features in common. In the conditions of low ionic strength media, the complexes of E2 with forms I and II of liver ER manifest differences in the kinetics and level of translocation into the cell nuclei. The differences disappearing with ionic strength increase. The differences disappearing with ionic strength increase. It is suggested that the different forms of liver ER participate in the realization of E2 multiple effects in the liver.

Animals↗