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PubMed1983

The effect of cortisol, progesterone, and transcortin on phytohemagglutinin-stimulated human blood mononuclear cells and their interplay.

The effect of transcortin on [3H]thymidine incorporation into phytohemagglutinin-stimulated human peripheral blood mononuclear cells and its influence on the well known suppressive effect of cortisol were investigated. Human transcortin by itself had no effect on thymidine incorporation between the concentrations of 0.25-1 X 10(-6) M. When transcortin was added to cortisol, the suppressive effect of cortisol decreased in proportion to the decrease in the protein-unbound cortisol concentration. We also investigated the influence of progesterone on transcortin-bound cortisol. When 0.5 and 1 X 10(-6) M transcortin, which contained 1 and 2 X 10(-7) M cortisol as a transcortin-bound form, were added to 5 X 10(-6) M progesterone, greater suppression of thymidine incorporation was observed that than produced by progesterone alone (86.1% and 81.3 for 0.5 and 1 X 10(-6) M transcortin, respectively). Moreover, when 5 X 10(-7) M transcortin containing the same amount of cortisol was added with 1, 2, and 5 X 10(-6) M progesterone, a greater suppression (92.6%, 74.1%, and 32.4% of control for 1, 2, and 5 x 10(-6) M progesterone) was demonstrated than that caused by progesterone alone (95.1%, 75.8%, and 49.5% of control for the corresponding concentrations of progesterone). This increased suppression was accompanied by an increase in the percentage of protein-unbound cortisol. These results indicate that unbound cortisol, whose concentration increases in the presence of progesterone, may be biologically active. The interaction between progesterone and cortisol may be modulated in part by the transcortin concentration.

Cells, Cultured↗
PubMed1986

Comparative study of primates' transcortin: immunoreactivity and steroid-binding activity.

To investigate the phylogenic aspect of transcortin (corticosteroid-binding globulin, CBG), the immunoreactivity of transcortin with anti-human transcortin antiserum was studied in primates. The anti-human transcortin antibody was recognized by plasma proteins obtained from Catarrhini, taxonomically the most evolved monkey group. The immunoreactivity was not observed in plasma obtained from Platyrrhini and Prosimiae, classified as less evolved monkey groups than Catarrhini. Though comparison of immunoreactivity among different classes of Catarrhini was difficult because of non-parallelism of their displacement curves, displacement of 125I-labelled human transcortin from the antiserum by 1:10 and 1:100 diluted plasma was highest in human followed by Pongidae, Cercopithecoidea. The immunoreactivity of thyroxine-binding globulin (TBG) with anti-human TBG antiserum was also examined. The anti-human TBG antibody was only recognized in plasma from Pan (anthropoid ape) among Pongidae, highly evolved monkeys among Catarrhini. The existence of immunoreactive transcortin and TBG to respective human protein antibody in the highly evolved ape agreed well with the cladogenetic division of primate species delineated by Goodman and Moore (1971). Cortisol-binding activity of transcortin was detected in all monkeys except three, tafted capuchin monkey, night monkey and cotton-headed tamarin, which belong to Platyrrhini. The absence of cortisol-binding activity in these animals might be attributed to high levels of endogenous cortisol and low cortisol-binding capacity of transcortin. It is speculated that the structure of the immunoreactive site in transcortin could be modified by evolution without affecting the biologically important site, the site for cortisol binding.

Animals↗
PubMed1986

Transcortin and vitamin D-binding protein levels in mouse serum.

The influence of age, sex and strain on the serum concentration of transcortin (corticosteroid-binding globulin) and vitamin D-binding protein (DBP) in mice was investigated. The effect of age was studied in two strains, C57BL/6JPfd and BALB/cmHeAPfd. The concentration of transcortin and DBP increased with age. In young animals the concentration of each protein showed a significant strain difference, which disappeared in older mice for DBP, but not for transcortin. In 7-day-old animals, no sex difference was observed for either protein, but in older animals a clear sex difference was found for transcortin. Adult males tended to have somewhat higher levels of DBP than adult females, but this difference was significant only on day 70. The variation in transcortin and DBP levels was further investigated in a large number of mouse strains. The DBP concentration did not markedly vary among strains (5.98-9.65 mumol/l in males and 5.08-8.85 mumol/l in females). Transcortin, however, showed marked strain variations, ranging from 0.72 to 2.06 mumol/l in males and from 1.02 to 4.55 mumol/l in females and there was a significant correlation (r = 0.66, n = 26, P less than 0.001) between the mean transcortin levels in males and females of different strains. Interstrain variation was much higher than intrastrain variation or variation among related strains, suggesting that the transcortin concentration is largely controlled by genetically determined factors. There was a significant correlation (r = 0.82, n = 9, P less than 0.01) between the mean corticosterone and transcortin concentrations (measured at 21.00 h).(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMedDate not supplied

[Identification of transcortin-synthesizing polyribosomes in the rat liver].

Transcortin biosynthesis in rats has been examined using liver slices technique. The incorporation of [14C]-labelled amino acids into the anti-transcortin-precipitable material of liver slices has been measured and compared with that of serum transcortin. It was shown that liver synthesized transcortin with an apparent molecular weight of 66 kDa on SDS-electrophoresis which co-migrated with authentic rat serum transcortin. In order to determine an intracellular distribution of transcortin-synthesizing polyribosomes, the binding character of [125J] anti-transcortin-IgG to free and membrane-bound rat liver polyribosomes has been studied. It was shown that after incubation of [125J] anti-transcortin-IgG with liver membrane-bound polyribosomes, the radioactivity was associated with the discrete polyribosome fraction in the heavy polyribosome region. In similar experiments the radioactivity of [125J] anti-transcortin-IgG bound to free polyribosomes was distributed throughout the polyribosome region.

Animals↗
PubMedDate not supplied

[Effect of transcortin on the corticosterone-transforming activity of cytosol from the rat liver].

The study of transcortin role in 3H-corticosterone metabolism has shown that transcortin of blood plasma from rats bearing Walker carcinosarcoma preserves the hormone conversion to dihydrocompounds 4 time less intensively than transcortin taken from healthy rats. Inactivated transcortin exerts no effect on the rate of formation of 5 beta-metabolites. Under the influence of homogeneous transcortin samples, a decrease in the content of 5 beta-reduced corticosterone metabolites is revealed to occur depending on transcortin concentration in the system. It is shown that in incubation systems where hormone is in the bound state the metabolism preserving capacity of transcortin depends on the temperature degree. The transcortin activity on corticosterone metabolism is supposed to be closely related to the intensity of its complexing with transcortin.

Animals↗
PubMed1987

Properties and serum levels of pregnancy-associated variant of human transcortin.

The amino acid composition, N- and C-terminal amino acid sequences, and the basic physicochemical and immunochemical properties of the recently discovered pregnancy-associated molecular variant of human transcortin (Strel'chyonok, O.A., Avvakumov, G.V. and Akhrem, A.A. (1984) Carbohydr. Res. 134, 133-140) have been found to be identical to those of transcortin from normal donor serum. This suggests the identity of polypeptide moieties of the two glycoproteins. The transcortin variant has a lower isoelectric point (3.5-4.1) than normal transcortin (3.6-4.2), and different electrophoretic mobility in low-porosity polyacrylamide gel (one band versus two for normal transcortin). These differences can be reasonably explained by different organization of the carbohydrate moieties of these glycoproteins due to diverse post-translational modification of a single polypeptide chain. The levels of transcortin variant in the maternal venous serum throughout normal gestation (447 donors in all) and on the fifth day after delivery, as well as in umbilical cord serum and extracts of term placenta, have been measured by a radioimmune assay. Analysis of the data obtained allowed us to conclude that the biosynthesis of pregnancy-associated transcortin variant occurs in some organ of the maternal organism rather than in the feto-placental system, and it is a characteristic of pregnancy as a unique physiological state of the female organism rather than a phenomenon caused by individual features of certain women. We assume that the transcortin variant takes part in the guided transport of corticosteroids and/or progestins into some tissues that develop in the course of gestation.

Amino Acid Sequence↗
PubMed1976

[Protein binding glucocorticoid hormones (transcortin) during peri-and postnatal ontogenesis and pregnancy in rats].

The constants of association and the energy of interaction between transcortin and cortisol, the binding ability and other characteristics of transcortin have been studied in the embryos, sexually immature and mature young and old females, females on the 14th and 21st days of pregnancy, immature and mature males. The constant of association in all the groups amounted to ca. 10(8) and the energy of interaction ca. 10 Cal/mole. The embryos and immature rats of both sexes are characterized by relatively low levels of the binding ability of transcortin. During the sexual maturation, the level of transcortin increased--insignificantly in males and markedly in females. The level of transcortin in the latter remained almost invariable during pregnancy and senescence. By the electrophoretic and sedimentation properties transcortin was the same in different groups. The high level of transcortin during pregnancy corresponded to the high level of hormones bound by transcortin, the level of these hormones in the embryos being much lower than in the mother.

Age Factors↗
PubMed1986

Phylogenetic study of transcortin using monoclonal antibodies.

We produced monoclonal antibodies that recognise three distinct epitopes of human transcortin. These epitopes are present on transcortin of humans with normal and altered transcortin levels, as well as on a variant with lower affinity for cortisol. One epitope is present on transcortin of Old World Monkeys and apes, the others are only present on transcortin of apes. The epitopes are not present on transcortin of other species. These results indicate that human transcortin contains a highly evolved and a more conserved part.

Animals↗
PubMed1975

A combined adsorption-gel filtration technique for the determination of the cortisol-binding capacity of transcortin.

A combined adsorption-gel filtration technique has been developed for the quantitation of the cortisol-binding capacity of transcortin: Endogenous steroids are removed from plasma by adsorption on uncoated charcoal. Saturation of the "stripped" binding sites of transcortin is accomplished by equilibrating the sample with a definite amount of labeled cortisol of low specific activity (0.1 muCi/mug). Transcortin-bound [4-14C]cortisol is isolated by gel filtration over Sephadex G-50 at 4 degrees C and measured by liquid scintillation counting. The cortisol-binding capacity of transcortin is calculated directly on the basis of the known specific activity of cortisol. The modification described eliminates methodological disadvantages associated with the original gel filtration procedures, i.e. the possible interference of various endogenous steroids with cortisol binding to transcortin, and the necessity of fluorometric or colorimetric determination of protein-bound cortisol. The values of the cortisol-binding capacity of transcortin in plasma obteined by this simplified assay are in close agreement with results reported in the literature (mean +/- S.D.): healthy males 261 +/- 23 mug/l) of transcortin-bound cortisol (n = 13), healthy nonpregnant females 255 +/- 31 mug/l (n = 15), and pregnant females prior to delivery 560 +/- 82 mug/l (n = 12).

Adsorption↗
PubMedDate not supplied

[Isolation of antiserum against rat transcortin and characteristics of specific antibodies].

Repeated chromatography of rat plasma protein on DEAE-cellulose, hydroxylapatite and subsequent gel-filtration through Sephadex G-200 were used to obtain a pure rat transcortin homogeneous upon polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate. The molecular weight of transcortin was about 66 kDa as determined by SDS-polyacrylamide gel electrophoresis. Immunization of a rabbit with the homogeneous preparation of rat plasma transcortin caused development of antibodies to transcortin. It was shown that the antibodies of rabbit antisera in the experiments made in vitro and in vivo neutralized 60 and 65% of 3H-corticosterone-transcortin complexes, respectively. Specific antibodies to the transcortin were isolated from the homogeneous fraction of IgG by affinity chromatography on transcortin-sepharose 4B. 125J-labelled antibodies were adsorbed by protein A-sepharose; IgG can be eluted by IM acetic acid as a sharp peak. The SDS-polyacrylamide gel electrophoresis demonstrated that affinity-eluted material contains 25 and 50 kDa polypeptides.

Animals↗
PubMed1982

Transcortin Leuven: a variant of human corticosteroid-binding globulin with decreased cortisol-binding affinity.

Genetic variation of human transcortin was investigated on neuraminidase-treated plasma samples by polyacrylamide gel isoelectric focusing followed by immunofixation of transcortin on cellulose-acetate strips. This procedure was applied systematically to 500 plasma samples obtained from individuals of Caucasian origin. Most samples showed one band focusing at pH 5.52. In three unrelated samples, a two-band pattern was obtained consisting of the normal band (pI 5.52) and a cathodic band of equal color intensity (pI 5.60). Family studies showed that this transcortin variant, which we call transcortin Leuven, is autosomally inherited. In a family of Polish origin two individuals homozygous for transcortin Leuven were found. A striking feature of transcortin Leuven is that it has a 2.6-fold reduced affinity for cortisol at 4 degrees C and a 3.6-fold reduced affinity at 28 degrees C. This lowered affinity is due to an enhanced dissociation rate of the transcortin-cortisol complex. As for normal asialotranscortin, a cortisol-induced charge difference of 0.15 pH unit was observed for this variant.

Female↗
PubMed1992

Testosterone destroys the transcortin-receptor complex.

Dissociation of the complex of transcortin receptor with immobilized transcortin in the presence of 10(-5) M testosterone has been shown with the use of affinity chromatography on transcortin-Sepharose. The specificity of this effect is confirmed by its abrogation in the presence of cortisol. The testosterone effect has been used for the elution of transcortin receptor from affinity column. The receptor retained transcortin-binding capacity after the elution and removal of testosterone. Characteristics of the receptor obtained by testosterone elution were identical with those of the transcortin eluted preparation.

Cell Membrane↗
PubMed1976

Studies of human transcortin at different pHs: circular dichroism, polymerisation and binding affinity.

The transcortin we have used in this work is extremely pure. This was shown by the polymerisation observed at pH 4. This polymerisation is never observed with an impure form of transcortin [4]. Moreover, since it is known that the presence of cortisol in the binding site is an essential condition to the activity of purified transcortin [5], it appears that a correlation between the secondary structure and the biological activity of the transcortin exists. The results we have obtained are summarized below: (1) The inhibition of the transcortin binding capacity essentially takes place between pH 5 and 4. (2) A reorganisation of the structure of the protein moiety is observed between pH 6.5 and 5.9. (3) A decrease of the helicity ratio is observed between pH 5 and 4. It appears therefore that, in the limits of experimental accuracy of CD measurements to determine the amount of beta-structure, no appreciable change of binding activity is taking place after the appearance of a large percentage of beta-structure between pH 6.5 and 6. On the other hand, the sudden decrease of protein activity at low pH is likely to be correlated with the disappearance of a well-defined helical region. Other biochemical and physical experiments would be of course necessary, in order to precise this first observation of a structure-function relationship in transcortin.

Binding Sites↗
PubMed1985

Transcortin modulates the effect of cortisol on mitogen-induced lymphocyte proliferation and immunoglobulin production.

In the present study we investigated whether transcortin modulates the in vitro effects of cortisol on the proliferation of human peripheral blood mononuclear cells (PBMC) stimulated by different mitogens and on mitogen-induced polyclonal immunoglobulin production. Physiological doses of cortisol (10-1000 nM) strongly inhibited the proliferation of PBMC stimulated by the monoclonal antibody OKT3 or by phytohemagglutinin. Addition of pure cortisol-free transcortin significantly reduced these inhibitory effects in a dose dependent manner. Transcortin (1 microM) caused a 3- to 4-fold reduction of the effects of 100 nM cortisol. Transcortin alone had no influence on the proliferation of stimulated PBMC. Polyclonal immunoglobulin production by PBMC stimulated with pokeweed mitogen was enhanced by physiological does of cortisol. A concentration of 100 nM cortisol caused an increase of immunoglobulin G and M production of 81 and 55% respectively. This effect was abolished by addition of 1 microM transcortin to the cultures, whereas transcortin alone had no effect. These results indicate that an evaluation of the effect of corticoids on lymphoid tissues should be based on the free cortisol level rather than on the total cortisol concentration.

Adult↗
PubMed1985

Transcortin and alpha 2u-globulin messenger RNA activities during turpentine-induced inflammation in the rat.

Previously we have shown that the serum concentration of transcortin and alpha 2u-globulin markedly decreases during turpentine-induced inflammation. In the present study transcortin and alpha 2u-globulin mRNA from healthy rats and from animals with inflammation was translated in a rabbit reticulocyte lysate system. Female rats had higher levels of translatable transcortin mRNA than male animals and the level of mRNA for transcortin and alpha 2u-globulin decreased rapidly during inflammation. These results indicate that the sex difference in the serum level of transcortin and the changes in serum transcortin and alpha 2u-globulin during inflammation are mainly determined by differences in the mRNAs in the liver.

Alpha-Globulins↗
PubMed1976

Placenta, transcortin, and localized immune response.

The syncytiotrophoblastic cells of the human placenta contain a cytoplasmic protein recognized by fluorescein-labeled transcortin-specific antibody. Purification of this protein from human placenta, by those methods employed for the purification of human plasma transcortin, yielded a protein that exhibited antigenic and biochemical similarity to plasma transcortin. Placental transcortin differs from plasma transcortin in that it has a smaller sedimentation coefficient (3S vs 3.75S) and binds cortisol less strongly. This purified protein is able to block the phytohemagglutinin response of maternal lymphocytes even more than serum transcortin. It is postulated that the biological role may be that of inhibiting the maternal cell-mediated immune response to the presence of the antigenic conceptus.

Chromatography, DEAE-Cellulose↗
PubMed1987

The influence of transcortin on adrenocorticotropin-stimulated corticosterone production in monolayer cultured rat adrenal cells.

To verify the influence of the protein binding status of steroids adjacent to adrenal cells on steroidogenesis, the effect of transcortin, a specific binding protein of cortisol or corticosterone, on adrenocorticotropin (ACTH)-stimulated corticosterone production in monolayer cultured rat adrenal cells was studied. The transcortin in concentration of 5 x 10(-7) M was loaded with 0, 2.5, 5 and 10 pg/ml ACTH-(1-24), and the cells were incubated for 2 and 4 hours. Since molar concentrations of corticosterone produced in the medium were below the transcortin concentration at all levels of stimulation, protein-unbound corticosterone in the medium may have been largely reduced by the addition of transcortin. However, the total corticosterone production was not influenced by the transcortin added to the medium. It was speculated that protein-unbound steroid within the concentration range modulated by transcortin in the area surrounding the adrenal cells may not affect adrenal steroidogenesis.

Adrenal Glands↗
PubMedDate not supplied

[Change in glucocorticoid-binding function of transcortin in acute gastroduodenal hemorrhaging].

The glucocorticoid-binding function of transcortin was studied in the blood serum of 31 patients with gastroduodenal ulcer complicated by moderate hemorrhage. The patients received a routine multimodality therapy. Sixteen donors serves as a control. Labelled cortisol was used to determine the time course of specific glucocorticoid saturation of transcortin. The Scatchard analysis defined the number of specific transcortin binding sites, the association and dissociation constants of cortisol-transcortin complexes. The blood levels of cortisol and insulin were measured using test kits (France). In patients with hemorrhage-complicated ulcer, the cortisol binding sites to transcortin substantially increased in number on days 7 to 14, and on the contrary, the association constant decreased. The serum content of endogenous cortisol significantly rose, starting from day 1 to day 14 of the onset of hemorrhage. Insulin levels significantly decreased only on days 14 of bleeding. In posthemorrhagic patients, the cortisol/insulin index drastically elevated and remained high within 14 days. A role of serum transcortin functional changes in patients with hemorrhage-complicated ulcerous disease in metabolic and immunogenetic processes.

Acute Disease↗