Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.27.5 (RNase)
17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Membrane fraction RNA isolated from rat pituitary tumor (GC) cells has been translated in a wheat germ extract. A product was synthesized which was immunologically related to growth hormone, but which migrated more slowly than growth hormone upon sodium dodecyl sulfate-acrylamide gel electrophoresis. The mobility of the cell-free product on gels of this type was unchanged by treatment with either KOH or RNase. The mobilities during paper electrophoresis of the methionine-containing tryptic peptides obtained from the cell-free product were identical to those obtained from growth hormone synthesized and secreted by the GC cells. Molecular weights for growth hormone and the cell-free product of 19,500 and 24,000, respectively, were determined by gel electrophoresis of these proteins together with marker proteins of known molecular weights. No protein with the properties of the cell-free product was detected after a 2 min incubation of the GC cells with [35S]methionine. However, treatment of the GC cells, with a protease inhibitor, L-1-tosylamide-2-phenyl-ethylchloromethyl ketone (TPCK), led to the appearance of a new polypeptide, immunologically related to growth hormone, and with a mobility on gels identical to that of the cell-free product. These results strongly imply that the cell-free product represents a growth hormone precursor (pregrowth hormone) which is rapidly converted to growth hormone in pituitary cells.
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PMID:Pregrowth hormone: product of the translation in vitro of messenger RNA coding for growth hormone. 106 Nov 24

Interactions of several proteins with glutathione-insulin transhydrogenase (GIT) have been investigated by determining their ability to inhibit degradation of 125I-labeled insulin catalyzed by GIT. The inhibition by every insulin analog (des-Asn-des-Ala-pork insulin, desoctapeptide-pork insulin, des-Ala-pork insulin, pork insulin, proinsulin, and guinea pig insulin) was competitive vs. competitive vs. insulin indicating that they function as alternate substrates. The insulin analogs with the least hormonal activity showed the highest potency as inhigitors of insulin degradation. Whereas native ribonuclease and lysozyme showed little or no inhibition, their scrambled forms (i.e. reduced and randomly reoxidized) showed competitive inhibition with a potency greater than that of insulin. These results suggest that the conformation of the substrate or inhibitor is probably the major factor in determining the specificity for (or binding to) the enzyme. Studies withother peptide hormones showed competitive inhibition with vasopressin and oxytocin and noncompetitive inhibition with glycagon. The inhibition with growth hormone could be either competitive or noncompetitive. The inhibition by glucagon and growth hormone (physiologic antagonists of insulin) could serve as a control mechanism to modulate the activity of enzyme. The following showed very little or no inhibition; the native and scrambled form of pepsinogen, trypsin inhibitor of beef pancreas and of lima bean, C-peptide of pork proinsulin, and heptapeptide (B23-B29) of insulin.
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PMID:Interaction of insulin analogs, glucagon, growth hormone, vasopressin, oxytocin, and scrambled forms of ribonuclease and lysozyme with glytathione-insulin transhydrogenase (thiol: protein-disulfide oxidoreductase): dependence upon conformation. 117 Aug 77

The administration of growth hormone to hypophysectomized rats caused an increase of ribonuclease activity in plasma within the limits of 70 to 200 per cent. An injection of actinomycin D, simultaneously with the growth hormone, inhibited this effect.
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PMID:[Significance of growth hormone for the regulation of ribonuclease activity in rat plasma (author's transl)]. 122 75

Using the cDNA coding for the human interferon alpha/beta receptor (IFNAR), the IFNAR gene has been physically mapped relative to the other loci of the chromosome 21q22.1 region. 32,906 base pairs covering the IFNAR gene have been cloned and sequenced. Primer extension and solution hybridization-ribonuclease protection have been used to determine that the transcription of the gene is initiated in a broad region of 20 base pairs. Some aspects of the polymorphism of the gene, including noncoding sequences, have been analyzed; some are allelic differences in the coding sequence that induce amino acid variations in the resulting protein. The exon structure of the IFNAR gene and of that of the available genes for the receptors of the cytokine/growth hormone/prolactin/interferon receptor family have been compared with the predictions for the secondary structure of those receptors. From this analysis, we postulate a common origin and propose an hypothesis for the divergence from the immunoglobulin superfamily.
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PMID:The structure of the human interferon alpha/beta receptor gene. 137 Aug 33

We have investigated the effects of recombinant human growth hormone (r-hGH) on the expression of hGH-receptor in a human hepatoma cell line (HuH 7). Levels of hGH-receptor mRNA in HuH 7 cells treated with different doses of r-hGH were measured by means of an RNase protection assay. Treatment with r-hGH at physiological concentrations (12.5, 25 and 50 ng/ml) resulted in an increase in hGH-receptor mRNA levels within 1 h of addition of the hormone. A steady state was reached after 3-4 h and maintained for at least 48 h. In contrast, treatment with supraphysiological r-hGH concentrations (150 and 500 ng/ml) led to a down-regulation of hGH-receptor mRNA levels during the first 3 h after hormone addition followed by an increase in hGH-receptor mRNA levels thereafter. Nuclear run-off assays demonstrated that these changes in hGH-receptor mRNA levels were a result of changes in the rate of transcription of the hGH-receptor gene. Cycloheximide (10 micrograms/ml) did not affect these changes in hGH-receptor gene transcription significantly, indicating that they are mediated by pre-existing factors and do not require new protein synthesis. These data demonstrate that r-hGH specifically regulates the rate of transcription of the hGH-receptor gene in a human hepatoma cell line.
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PMID:Regulation of human growth hormone receptor gene expression by human growth hormone in a human hepatoma cell line. 166 2

Insulin-like growth factor I (IGF I), a potent growth factor in vitro, is present in blood and in multiple tissues and is a major mediator of the effects of growth hormone on postnatal growth. IGF I is internalized and retained largely intact in cultured vascular endothelial cells. Neovasculature transiently expresses IGF I immunoreactivity, but it is not known whether this represents internalization of the circulating growth factor or vascular cell synthesis of IGF I. As an initial approach to defining the role of endogenous production of IGF I in the growth program of the vessel wall, Northern hybridizations were performed with RNA from cultured rat aortic smooth muscle cells and bovine aortic endothelial cells. Rat aortic smooth muscle cells expressed three primary IGF I messenger RNA transcripts sized 8.2, 1.7, and 0.9-1.2 kb. Bovine aortic endothelial cells expressed one major and one minor IGF I transcript of 2.1 and 1.6 kb, respectively. IGF I gene expression in smooth muscle cells was also demonstrated by ribonuclease protection assays using a rat exon 3 riboprobe. Both endothelial and vascular smooth muscle cells secreted IGF I, as detected by radioimmunoassay of conditioned medium after separation of IGF I from its binding proteins by gel filtration chromatography. Because IGF I stimulates growth of vascular cells, characterization of IGF I gene expression in blood vessels may be key to understanding developmental as well as abnormal growth in the cardiovascular system.
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PMID:Insulin-like growth factor I gene expression in vascular cells. 170 44

Mice transgenic for growth hormone (GH) develop progressive glomerulosclerosis. The compositions of kidney extracellular matrix (ECM) and ECM mRNA were examined. The glomerulosclerotic areas in GH mice contained types I and IV collagen, laminin, and basement membrane heparan sulfate proteoglycan (HSPG), which increased with age. The type IV collagen, laminin B2, and HSPG mRNA levels in GH mice, measured by a solution hybridization RNase protection assay, were increased over normal littermates. These findings suggest that the accumulation of ECM components in the glomeruli of GH mice is regulated at the transcriptional level and that glomerulosclerosis is, in part, due to the excess production of ECM rather than simply a reduction in its turnover. The glomerular lesions in GH mice resemble diabetic nephropathy and may allow further dissection of the molecular basis of certain forms of glomerulosclerosis.
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PMID:Glomerulosclerosis in mice transgenic for growth hormone. Increased mesangial extracellular matrix is correlated with kidney mRNA levels. 202 27

RNase mapping experiments show that the bovine growth hormone (bGH) poly(A) region forms an extensive hairpin loop. Mutants were prepared to change poly(A) region pre-mRNA structure and cleavage site efficiency without altering necessary sequences. An inverted repeat which includes the poly(A) cleavage site was created by insertion of a linker upstream of the poly(A) region to compete with any wild-type secondary structure. RNA mapping analyses show alterations in the nuclease accessibility of this mutant at the natural site of cleavage. This mutant shows a 75% drop in relative reporter gene expression at the steady-state protein and RNA levels. When the linker is inserted as a direct repeat, expression is equivalent to wildtype levels. To show that transcription was not terminated by the inverted repeat, the SV40 late poly(A) region was inserted downstream. These mutants show restored expression and processing at the downstream site. Our experiments reveal that the conformation of the poly(A) site pre-mRNA is important in mediating efficient cleavage-polyadenylation.
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PMID:Alterations in the pre-mRNA topology of the bovine growth hormone polyadenylation region decrease poly(A) site efficiency. 257 Nov 27

Insulin has been shown to inhibit rat growth hormone (GH) gene transcription. The effects of insulin were therefore tested on the expression of a transfected human GH gene. A 2.6-kilobase EcoRI fragment of the human GH gene was propagated in pUC18 and transfected by calcium-phosphate shock into HeLa and GC cells, respectively. Transfected cells grown in serum-free medium for 72 h expressed human GH measured by specific radioimmunoassay, incorporation of [35S] methionine into newly synthesized GH, and the presence of the appropriately sized protected transcripts seen after RNase protection assay. Immunoprecipitation analysis showed that insulin (0.7-7 nM) suppressed both the basal as well as the hydrocortisone (100 nM)-stimulated expression of newly synthesized 22-kDa GH in a dose-dependent fashion. Insulin (7 nM) also suppressed the basal and hydrocortisone-stimulated GH mRNA transcripts in these cells. Control nontransfected cells did not express human GH. Cells transfected with the truncated pOGH gene and pTKGH gene failed to respond to insulin treatment, whereas the human GH promoter was able to confer insulin responsiveness to the chloramphenicol acetyltransferase reporter gene. cis-Acting regulatory sequences residing on the 497-base pair 5'-flanking region of the human GH gene therefore appear to be a requirement for human GH gene response to the insulin signal.
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PMID:Insulin regulates expression of the human growth hormone gene in transfected cells. 290 52

In these studies, we examined the effect of excess levels of growth hormone (GH) on rat insulinlike growth factor I (IGF-I) gene expression in streptozocin-induced diabetes mellitus. A solution hybridization/RNase protection assay was used to simultaneously quantitate the relative tissue content of the variant IGF-I mRNA species arising from alternative splicing in the region encoding the COOH-terminal extension E-peptide (IGF-Ia and IGF-Ib). IGF-Ia and IGF-Ib mRNAs were markedly decreased in liver, kidney, and lung tissues of diabetic rats. Although GF stimulates IGF-I gene expression, chronic GH excess from implanted somatomammotropic tumors did not appropriately induce tissue IGF-I mRNA content in diabetic animals. Treatment of diabetic rats with insulin for 1 wk restored basal and GH-stimulated IGF-Ia and IGF-Ib mRNA content toward that present in tissues of nondiabetic rats. The ratio of IGF-Ia to IGF-Ib mRNA remained relatively constant for each tissue and was not affected by the diabetic state, chronic GH hyperstimulation, or insulin therapy, suggesting that posttranscriptional splicing is not a regulated event in these conditions. Thus, both circulating IGF-I levels and tissue IGF-I gene expression are profoundly decreased in this model of experimental diabetes. Diminished tissue availability of IGF-I from endocrine and/or paracrine sources may be responsible for the growth retardation seen in uncontrolled diabetes mellitus.
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PMID:Coordinate decrease of tissue insulinlike growth factor I posttranscriptional alternative mRNA transcripts in diabetes mellitus. 292 6


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