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D T Kurtz

Publications and source records attributed to D T Kurtz.

8 recordsLinked to original sources
PubMed1978

Glucocorticoid induction of hepatic alpha2u-globulin synthesis and messenger RNA level in castrated male rats in vivo.

alpha2u-Globulin is a male rat liver protein of Mr = 20,000 which is synthesized in the liver of adult male rats, secreted into the serum, and excreted in the urine. Its function is unknown. The hepatic synthesis of this protein is under complex hormonal control. We had previously shown that castration of male rats diminishes hepatic alpha2u-globulin synthesis and the level of its mRNA, and that administration of androgen to these castrated animals results in the reinduction of the synthesis of this protein and the level of its mRNA. We now report that alpha2u-globulin synthesis and the level of its mRNA can be fully reinduced in castrated males by administration of glucocorticoid alone. This induction is much more rapid than the androgenic induction and is inhibited by the glucocorticoid antagonist progesterone. Administration of glucocorticoid to intact male animals does not induce alpha2u-globulin synthesis above normal levels; however, if alpha2u-globulin synthesis has been depressed in intact male rats by pretreatment with estrogen or cyproterone acetate, the level of this protein can be reinduced by administration of glucocorticoids. The implications for the control of alpha2u-globulin gene expression are discussed.

Animals↗
PubMed1978

Transcription of the alpha2u-globulin gene in male rat liver nuclei in vitro.

Alpha2u-globulin is a male rat liver protein under multihormonal control which represents approximately 1% of hepatic protein synthesis. We have measured the rate of transcription of the alpha2u-globulin gene using a nuclear cell-free transcriptional system with mercurated CTP as substrate for the endogenous RNA polymerases. The newly synthesized, mercurated RNA was purified free of endogenous RNA by chromatography on sulfhydryl agarose and hybridized to 3H-labeled alpha2u-globulin cDNA. It was found that, in male rat liver nuclei, alpha2u-globulin RNA sequences represent 0.005% of the total newly synthesized RNA. Actinomycin D or alpha-amanitin completely blocks the synthesis of alpha2u-globulin RNA in these nuclei. No alpha2u-globulin RNA synthesis was detectable in female rat liver nuclei. Thus, within the limits of our detection the absence of hepatic alpha2u-globulin mRNA in female rats appears to be due to a lack of transcription of the alpha2u-globulin gene in these animals.

Alpha-Globulins↗
PubMed1977

Multihormonal induction of hepatic alpha2u-globulin mRNA as measured by hybridization to complementary DNA.

A procedure is presented for the preparation of a (3)H-labeled complementary DNA (cDNA) specific for the mRNA coding for alpha(2u)-globulin, a male rat liver protein under multihormonal control that represents approximately 1% of hepatic protein synthesis. Rat liver polysomes are incubated with monospecific rabbit antiserum to alpha(2u)-globulin, which binds to the nascent alpha(2u)-globulin chains on the polysomes. These antibody-polysome complexes are then adsorbed to goat antiserum to rabbit IgG that is covalently linked to p-aminobenzylcellulose. mRNA preparations are thus obtained that contain 30-40% alpha(2u)-globulin mRNA. A labeled cDNA is made to this alpha(2u)-globulin-enriched mRNA preparation by using RNA-dependent DNA polymerase (reverse transcriptase). To remove the non-alpha(2u)-globulin sequences, this cDNA preparation is hybridized to an RNA concentration x incubation time (R(0)t) of 1000 mol of ribonucleotide per liter x sec with female rat liver mRNA, which, though it shares the vast majority of mRNA sequences with male liver, contains no alpha(2u)-globulin mRNA sequences. The cDNA remaining single-stranded is isolated by hydroxylapatite chromatography and is shown to be specific for alpha(2u)-globulin mRNA by several criteria. Good correlation was found in all endocrine states studied between the hepatic level of alpha(2u)-globulin, the level of functional alpha(2u)-globulin mRNA as assayed in a wheat germ cell-free translational system, and the level of alpha(2u)-globulin mRNA sequences as measured by hybridization to the alpha(2u)-globulin cDNA. Thus, the hormonal control of hepatic alpha(2u)-globulin synthesis by sex steroids and thyroid hormone occurs through modulation of the cellular level of alpha(2u)-globulin mRNA sequences, presumably by hormonal control of transcriptive synthesis.

Alpha-Globulins↗
PubMed1976

Effects of sex hormones on the level of the messenger RNA for the rat hepatic protein alpha 2u globulin.

Alpha 2u Globulin is a protein synthesized in the liver, secreted into the serum, and excreted in the urine of mature male rats. The effects of androgens and estrogens on the level of the messenger RNA coding for the male rat hepatic protein have been investigated. Castrated male rats have reduced levels of alpha 2u globulin in serum and liver cytosol, as measured by a radial immunodiffusion assay. The livers from these castrated males were found to contain similarly reduced levels of the mRNA coding for alpha 2u globulin, as measured in an mRNA-dependent wheat germ cell-free translational system. Administration of dihydrotestosterone to castrated males resulted in increased levels of alpha 2u globulin in liver and serum and this increase in the level of the protein following androgen administration was accompanied by a parallel increase in the functional level of alpha 2u globulin mRNA. Administration of estradiol-17 beta to intact male rats gradually diminishes the levels of alpha 2u globulin in liver and serum. The livers from these estrogen-treated males were found to contain alpha 2u globulin mRNA at similarly reduced levels. The time course of the disappearance of the alpha 2u globulin mRNA following estrogen treatment parallels the disappearance of the protein in liver cytosol and serum. These results indicate that sex steroids affect the synthesis of the hepatic protein alpha 2u globulin by acting pretranslationally, possibly at the level of transcription. Although the liver had not been considered a primary target tissue for sex hormones, these results indicate that sex steroids can affect certain hepatic functions in a manner consistent with the accepted model for the action of steroid hormones on their target tissues.

Alpha-Globulins↗
PubMed1976

Comparison of in vivo translation rates and messenger RNA levels of alpha2U-globulin in rat liver and Morris hepatoma 5123D.

The synthesis of the male rat hepatic protein alpha2U-globulin has been examined in Morris hepatoma 5123D and male host liver using pulse incorporation of labeled amino acids in vivo, followed by immunoprecipitation of the newly synthesized alpha2U-globulin from the soluble protein fraction of liver and hepatoma tissue. It was found that no alpha2U-globulin synthesizes alpha2U-globulin at a normal level (0.9 to 1.0% of total hepatic protein synthesis). A variety of liver-derived cell culture lines also did not have alpha2U-globulin synthesis. The level of the specific mRNA coding for alpha2U-globulin can be quantitated using in vitro translation of polyadenylate-containing RNA in a Krebs II ascites cell-free translational system, followed by immunoprecipitation of the alpha2U-globulin synthesized in vitro. Using this technique, it was found that host liver contained alpha2U-globulin mRNA at normal levels, whereas hepatoma tissue contained no detectable mRNA coding for this protein. Thus, alpha2U-globulin synthesis is deleted in the minimal-deviation hepatoma 5123D as a consequence of the inability of that tissue to produce functional mRNA coding for alpha2U-globulin. The implications for the regulation of gene expression in malignant cells are discussed.

Alpha-Globulins↗