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J Carlstedt-Duke

Publications and source records attributed to J Carlstedt-Duke.

85 records · Page 5Linked to original sources
PubMed1982

Glucocorticoid-binding proteins in rat liver.

The distribution, metabolism and protein-binding of [3H] corticosterone in the rat liver was studied with respect to time and sex. The maximum recovery from the cell nuclei occurred 5 min after injection of the steroid. At this time, ten times more radioactivity was recovered from the liver cell nuclei of male animals compared to females. The recovered radioactivity in the cell nuclei was identified as mainly unmetabolised corticosterone and 5 alpha-dihydrocorticosterone. The radioactivity bound to the cytosolic glucocorticoid receptor protein also appeared to consist of unmetabolised corticosterone and 5 alpha-dihydrocorticosterone. However, 5 alpha-dihydrocorticosterone was found to have very little biological activity. The glucocorticoid receptor was found to exist in two forms with Stokes radii of 6.1 and 3.6 nm, respectively, following in vivo labelling with [3H] dexamethasone. The 6.1 nm form could be converted into the 3.6 nm form by incubation with trypsin, papain, alpha-chymotrypsin or an extract of purified rat liver lysosomes. Further incubation resulted in an even smaller form with a Stokes radius of 1.9 nm. With the help of biospecific adsorption chromatography based on the differential affinity of the activated and nonactivated complexes for DNA, the 6.1 nm form of the glucocorticoid-receptor complex was purified to near homogeneity by a rapid and simple technique. An immunoglobulin fraction from serum of a rabbit immunized with a highly purified preparation of glucocorticoid receptor contained specific antibodies to the receptor. The antibodies cross-reacted with the glucocorticoid receptor from human normal lymphocytes, chronic lymphatic leukemia cells and human hippocampus. Activated glucocorticoid receptor protein binds selectively in vitro to a cloned fragment of murine mammary tumor virus DNA. In contrast, the receptor fails to bind selectively to DNA restriction fragments from E coli plasmids pBR 322 and RSF 2124 or from bacteriophages alpha and T4.

Animals↗
PubMed1981

Characterization of an antiserum against the glucocorticoid receptor.

An immunoglobulin (IgG) fraction from serum of a rabbit immunized with a highly purified preparation of glucocorticoid receptor from rat liver cytosol contained specific antibodies to glucocorticoid receptor. This was shown following incubation of the [3H]triamcinolone acetonide-glucocorticoid receptor (TA-GR) complex with the IgG fraction by (I) adsorption of the [3H]triamcinolone acetonide-glucocorticoid receptor (TA-GR) complex with the IgG fraction by (I) adsorption of the [3H]TA-GR-antibody complex to protein A linked to Sepharose, (II) an increased sedimentation rate of the [3H]TA-GR-antibody complex compared to that of the [3H]TA-GR complex, and (III) an increased molecular size of the [3H]TA-GR-antibody complex when compared to that of the [3H]TA-GR complex as judged from gel filtration. The antibody fraction was characterized with regard to titer, cross-reactivity and specificity. The antibodies cross-reacted with the glucocorticoid receptor from various rat tissues (liver, thymus and hippocampus), as well as with the glucocorticoid receptor from human normal lymphocytes, chronic lymphatic leukemia cells and human hippocampus. In the rat liver, the antibody bound to both the nuclear and the cytosolic glucocorticoid receptor (stokes radius 6.1 nm). It did not cross-react with the proteolytic fragments of the glucocorticoid receptors, the 3.6 nm complex or the 1.9 nm complex. Binding of the antibodies was not seen to the androgen, estrogen or progestin receptors in rat or to rat serum transcortin. With an indirect competitive ELISA (enzyme-linked immunosorbent assay) combined with various separation techniques, based on different physicochemical principles, it was shown that the glucocorticoid receptor was the only detectable antibody binding protein from rat liver cytosol using this assay system. These findings also indicate an immunochemical similarity between glucocorticoid receptors in different tissues as well as in different species, but not between glucocorticoid receptors and other steroid hormone receptor proteins. The cytosolic and nuclear glucocorticoid receptors in rat liver were shown to be immunochemically similar.

Animals↗
PubMed1981

Purified glucocorticoid receptors bind selectively in vitro to a cloned DNA fragment whose transcription is regulated by glucocorticoids in vivo.

Activated glucocorticoid receptor protein, purified to 40-60% homogeneity from rat liver extracts, binds selectively in vitro to a cloned fragment of murine mammary tumor virus (MTV) DNA. The DNA fragment tested contains about half of the sequences present in intact MTV DNA, and its rate of transcription, like that of the intact viral element, is strongly stimulated by glucocorticoids when it is introduced into the genome of a receptor-containing cell. In contrast, the receptor fails to bind selectively to DNA restriction fragments from E. coli plasmids pBR322 and RSF2124 or from bacteriophages lambda and T4. Preliminary experiments to localize regions within MTV DNA responsible for selective binding have revealed thus far one subfragment that fails to bind the receptor and one selectively bound subfragment that maps far downstream from the 5' terminus of the normal RNA transcript. These studies are consistent with the notion that steroid receptors may modulate rates of transcription by recognizing specific DNA sequences within or near the regulated genes.

Animals↗
PubMed1979

Purification of the glucocorticoid receptor from rat liver cytosol.

The [3H]-triamcinolone acetonide-labeled glucocorticoid receptor from rat liver cytosol was purified to 85% homogeneity according to sodium dodecyl sulfate gel electrophoresis. It consisted of one subunit with a molecular weight of 89,000 and had one ligand-binding site per molecule. The purification involved sequential chromatography on phosphocellulose, DNA-cellulose twice, and Sephadex G-200. Between the two chromatography steps on DNA-cellulose, the receptor was heat activated. The receptor was affinity eluted from the second DNA-cellulose column with pyrodixal 5'-phosphate. The purification achieved in the first three chromatographic steps varied between 60 and 95% homogeneity in different experiments. After chromatography on the second DNA-cellulose column, the steroid.receptor complex had a Stokes radius of 6.0 nm and a sedimentation coefficient of 3.4 S in 0.15 M KCl. In the absence of KCl, the sedimentation coefficient was 3.6 S. After concentration on hydroxylapatite, the steroid.receptor complex was analyzed by isoelectric focusing in polyacrylamide gel. The radioactivity was shown to focus together with the major protein band with pI 5.8. Following limited proteolysis with trypsin, the radioactivity, together with the major protein band, focused at pI 6.2 as previously described for the unpurified steroid.receptor complex.

Animals↗
PubMed1977

Formation and characteristics of hepatic dexamethasone-receptor complexes of different molecular weight.

The dexamethasone-binding receptor protein in rat liver cytosol has a Stokes radius of 61 A and a sedimentation coefficient of 4.0 S. In contrast, cell nuclei labelled with [3H]dexamethasone in vivo or in vitro (reconstitution experiments with [3H]dexamethasone-labelled cytosol and isolated unlabelled nuclei) contain a high-salt-extractable dexamethasone-receptor complex with a Stokes radius of 30-36 A and a sedimentation coefficient of 3.2 S. Exposure of liver homogenate or 1000 X g homogenate supernatant to low ionic strength during preparation of cytosol resulted in conversion of the 61 A to a 36 A complex very similar to the intranuclear form of dexamethasone receptor. 61 leads to 36 A complex-converting activity was present in both the 100 X g-10 000 X g sediment of liver homogenate, from which it could be extracted by hypotonic media, and in the liver cell nuclei, from which it could be extracted by hypertonic media. Mild digestion of the 61 A dexamethasone-receptor complex with trypsin also gave rise to a complex with a Stokes radius of 36 A. Reconstitution experiments with isolated liver cell nuclei indicated that both the 61 A and 36 A dexamethasone-receptor complexes were taken up by the nuclei; reextraction of the nuclei incubated with the 61 A complex revealed that this form had been converted to the 30-36 A complex. Further digestion of the 61 and 36 A [3H]dexamethasone-receptor complexes with hypotonic extract of the 1000 X g-10 000 X g sediment of liver homogenate or with trypsin resulted in formation of a third complex with Stokes radius of 19 A and a sedimentation coefficient of 2.5 S. The approximate molecular weights of the 61, 36 and 19 A dexamethasone-receptor complexes were calculated as 102 000, 46 000 and 19 000, respectively, and the frictional ratios of the molecules as 1.84, 1.38 and 1.00, respectively. It is concluded that the nuclear 30-36 A dexamethasone-receptor complex is formed from the cytosol 61 A complex by proteolytic digestion and that this latter protein contains at least two sites with a relatively high sensitivity to protelytic cleavage.

Animals↗
PubMed1977

Interactions of corticosterone, 5alpha-dihydrocorticosterone and dexamethasone with proteins in rat-liver cytosol.

The intracellular binding of [3H]corticosterone and [3H]dexamethasone and their metabolites to macromolecules in rat liver cytosol was studied in vivo and in vitro. The macromolecules binding corticosterone and its metabolites were characterized as (a) a steroid conjugate-binding (Stokes radius 2.5 nm and sedimentation coefficient 4.1 S in high ionic strength; pI 8.7, (b) transcortin and (c) a glucocorticoid "receptor". Competition experiments indicate that corticosterone and dexamethasone bind to the same site of the glucocorticoid receptor molecule. Different Stokes radii between the corticosterone-receptor and the dexamethasone-receptor complexes (6.9 and 6.3 nm, respectively, in high ionic strength) indicate that the two ligands induce different conformations of the receptor protein. This may be of importance when explaining the qualitative differences between the cellular effects of natural and synthetic glucocorticoids. 5alpha-Dihydrocorticosterone, on the other hand, competed to a very limited extent with dexamethasone for binding sites on the receptor. An assay of the inductive effect on liver tyrosine aminotransferase and tryptophan oxygenase indicated that 5alpha-dihydrocorticosterone was practically devoid of glucocorticoid activity. It is concluded that 5alpha-dihydrocorticosterone probably does not act as the mediator of corticosterone action in rat liver.

Adrenalectomy↗
PubMed1975

Sexual differences in hepatic metabolism and intracellular distribution of corticosterone studied by pulse labeling with (1,2,6,7-3H)corticosterone.

The subcellular distribution of corticosterone and its metabolites in liver was studied 5, 30, and 90 min after injection of (1,2,6,7-3/)corticosterone in adult male and female rats that were adrenalectomized or hypophysectomized: 5 min after administration of isotope, the adrenalectomized male rats contained ten times as much labeled unconjugated corticosterone, 5alpha-dihydrocorticosterone, and 3alpha- and 3beta,11beta,21-trihydroxy-5alpha-pregnan-20-one on the nuclear fraction than the corresponding female rats. The metabolites of corticosterone in the soluble fraction of liver from adrenalectomized females occurred as about 90 per cent steroid monosulfates and disulfates already 5 min after administration of isotope. In contrast, the soluble fraction of liver from males contained only 38 per cent labeled monosulfate 5 min after injection of (1,2,6,7-3H)corticosterone. The individual labeled metabolites from the different subcellular fractions were identified by thin-layer and radio-gas chromatography. The major metabolites found in the female were mono- and disulfurylated 3alpha,11beta,15,21-tetrahydroxy-5alpha-pregnan-20-one, 3alpha,15,21-trihydroxy-5alpha-pregnane-11,20-dione, and 3alpha,11beta,21-trihydroxy-5alpha-pregnan-20-one. The predominant metabolites in the male were 5alpha-pregnane-3alpha(and 3beta),11beta,20beta,21-tetrol and 3beta,11beta,21-trihydroxy-5alpha-pregnan-20-one which mainly occurred as mono- and disulfates. Hypophysectomized female rats showed a corticosterone metabolite pattern with almost no 15-hydroxylated metabolites but with large amounts of isomers of pregnane-3,11beta,20beta,21-tetrol, i.e., a "masculinized" pattern. It is concluded that hepatic intracellular metabolism and transport of corticosterone in vivo in rats are characterized by large sexual difference which are at least partly under hypophyseal control.

Adrenalectomy↗