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:3.1.27.1 (RNase)
16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The amino- and carboxyl-terminal globular domains of type VI collagen are composed of several homologous modules similar to the type A collagen-binding modules present in von Willebrand factor. The human alpha 3(VI) chain that contributes most of the amino-terminal globule appears heterogeneous in size as a result of alternative splicing of two exons (Stokes D. G., Saitta, B., Timpl, R., and Chu, M.-L. (1991) J. Biol. Chem. 266, 8626-8633). In the present study, we report a further characterization of the 5'-end of the gene of the human alpha 3(VI) chain and show that transcription initiates at multiple sites. Southern blotting and DNA sequencing indicate that there is an additional type A exon (A9/N10) at about 1.8 kilobase pairs downstream of the exon coding for the signal peptide. The open reading frame of this additional exon reveals 1 cysteine and three potential N-glycosylation sites. Polymerase chain reaction, Northern blotting, and RNase protection assays demonstrate that exon A9/N10 is subject to alternative splicing in normal and tumor cell lines and that this generates more protein variants of the alpha 3(VI) chain than expected before. A comparison with the corresponding amino-terminal globule of the chicken alpha 3(VI) chain shows the presence of 1 additional cysteine in this portion of the molecule and suggests that human type VI collagen has more possibilities for structural and functional variations compared to chicken type VI collagen.
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PMID:The human type VI collagen gene. mRNA and protein variants of the alpha 3 chain generated by alternative splicing of an additional 5-end exon. 133 40

A TSH receptor (TSH-R) cDNA has been isolated from a human thyroid lambda GT11 library. Unexpectedly, several cDNAs encoding the human LH/CG receptor (LH/CG-R), previously thought to be expressed solely in gonadal cells, were also isolated from the thyroid library. The receptors are structurally related, consisting of a signal sequence, a large extracellular amino terminal domain, seven membrane spanning domains, and a short carboxyl-terminal portion. The TSH-R is encoded by a single 4.2 kilobase mRNA specific to the thyroid. Introns were not present in any hTSH-R cDNAs examined, however, sequencing of several LH/CG-R cDNAs and RNase protection experiments demonstrated that the majority of hLH/CG-R mRNA in the thyroid is incompletely spliced. Consequently, tissue-specific splicing may be an important step in the regulation of the glycoprotein hormone receptor family.
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PMID:Isolation of TSH and LH/CG receptor cDNAs from human thyroid: regulation by tissue specific splicing. 229 30

This paper further characterizes the estrogen-binding protein we have described in the cytosol of the yeast Saccharomyces cerevisiae. [3H]Estradiol was used as the radioprobe, and specific binding of cytosol fractions was measured by chromatography on Sephadex minicolumns. Other 3H-steroids did not exhibit specific binding. [3H]Estradiol binding was destroyed by treatment with trypsin, but not RNase, DNase, or phospholipase; N-ethylmaleimide substantially decreased the binding. The yeast did not metabolize estradiol added to the medium, and extraction and chromatography of the bound moiety showed it to be unmetabolized estradiol. Scatchard analysis of cytosol from both a and alpha mating types as well as the a/alpha diploid cell revealed similar binding properties: an apparent dissociation constant or Kd(25 degrees) for [3H]estradiol of 1.6-1.8 nM and a maximal binding capacity or Nmax of approximately 2000-2800 fmol/mg of cytosol protein. Gel exclusion chromatography on Sephacryl S-200 and high performance liquid chromatography suggested a Stokes radius of approximately 30 A. Sucrose gradient centrifugation showed a sedimentation coefficient of approximately 5 S, and the complex did not exhibit ionic dependent aggregation. The estrogen binder in S. cerevisiae differed in its steroidal specificities from classical mammalian estrogen receptors in rat uterus. 17 beta-Estradiol was the best competitor, 17 alpha-estradiol had about 5% the activity, and diethylstilbestrol exhibited negligible binding affinity as did tamoxifen, nafoxidine, and the zearalenones. In summary, a high affinity, stereospecific, steroid-selective binding protein has been demonstrated in the cytosol of the simple yeast S. cerevisiae. We speculate that this molecule may represent a primitive hormone receptor system, possibly for an estrogen-like message molecule.
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PMID:Characterization of an estrogen-binding protein in the yeast Saccharomyces cerevisiae. 636 45

Binding experiments with the cytosolic androgen receptor from murine skeletal muscle yield with testosterone a biphasic saturation curve and a biphasic Scatchard plot. These binding characteristics result from the conversion of 8 S receptor (KD = 1,4 X 10(-10) M) into 4-5 S receptor (KD = 1,2 X 10(-9) M). This conversion is androgen dependent and is facilitated in vitro by either UV-irradiation or by methods known to activate steroid hormone receptor complexes to a nuclear binding form (e.g. high ionic strength or elevated temperature). The measured data show that both receptor forms are in a complex dissociation equilibrium. The reassociation of the 4-5 S receptor to form the 8 S complex is inhibited by RNase.
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PMID:Correlation of the 4-5 S form and the 8 S form of the cytosolic androgen receptor in murine skeletal muscle. 667 45

Mechanisms regulating responses of the ovine uterus to endocrine and paracrine signals during the estrous cycle and pregnancy are likely to require tissue- and cell-specific regulation of steroid hormone receptor gene expression. To determine effects of day and pregnancy status (cyclic or pregnant) on uterine estrogen receptor (ER) and progesterone receptor (PR) gene expression, ewes were hysterectomized either on Day 1 (Day 0 = estrus/mating), 6, 11, 13, or 15 of the estrous cycle (n = 3/day) or on Day 11, 13, 15, 17, or 25 of early pregnancy (n = 5/day). Steady state levels of ER and PR mRNA were determined in endometrial and myometrial tissues by slot-blot hybridization and ribonuclease protection assays, respectively, using homologous ovine ER and PR cRNA probes. Changes in spatial expression of ER and PR mRNA and protein in uterine tissue sections were determined by in situ hybridization and immunocytochemical analyses. In cyclic ewes, steady state levels of endometrial ER mRNA were highest on Day 1, declined between Days 1 and 6, and increased between Days 11 and 15. However in pregnant ewes, endometrial ER mRNA levels decreased between Days 11 and 15 and increased slightly between Days 15 and 25. In cyclic ewes, levels of myometrial ER mRNA were highest on Day 1, decreased to Day 6, and remained low thereafter. In cyclic ewes, endometrial PR mRNA levels were highest on Day 1, decreased between Days 1 and 11, and then increased between Days 13 and 15. In cyclic ewes, myometrial PR mRNA levels were highest on Day 1 and declined thereafter. Endometrial PR mRNA levels were not different between cyclic and pregnant ewes on Days 11, 13, and 15. In pregnant ewes, PR mRNA levels were low on Day 11, increased between Days 11 and 17, and decreased between Days 17 and 25. In pregnant ewes, myometrial PR mRNA levels were low and did not change between Days 11 and 25. In situ hybridization and immunocytochemical analyses revealed distinct tissue- and cell type-specific alterations in uterine ER and PR mRNA and protein expression during the estrous cycle and early pregnancy that generally paralleled overall changes in steady state levels of ER and PR mRNAs. In the endometrium, the most striking observation was that PR mRNA and protein expression disappeared from the luminal and shallow glandular epithelium between Days 6 and 13 of the estrous cycle, whereas ER mRNA and protein expression was low on Days 6 and 11 and increased between Days 11 and 15 in the luminal and shallow glandular epithelium. During early pregnancy, expression of ER and PR mRNAs, as well as ER and PR protein, was very low or absent in the luminal and shallow glandular epithelium between Days 13 and 25 of pregnancy. Moreover, ER and PR mRNA and protein were consistently present at low levels in the stroma and deep glandular epithelium in both cyclic (Days 11-15) and pregnant (Days 11-25) ewes. Collectively, results suggest that uterine ER and PR gene expression is regulated in a tissue- and cell type-specific manner during the estrous cycle and early pregnancy.
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PMID:Temporal and spatial alterations in uterine estrogen receptor and progesterone receptor gene expression during the estrous cycle and early pregnancy in the ewe. 856 11

The GH-releasing hormone receptor (GHRH-R) is a critical link between hypothalamic GH-releasing hormone (GHRH) and pituitary GH secretion. However, the factors that regulate GHRH-R are not well understood. Despite the importance of thyroid hormone and glucocorticoids in influencing the GH axis in vivo, it is not known whether these hormones act directly at the pituitary to regulate expression of GHRH-R. We tested the effects of T3 and hydrocortisone on GHRH-R gene expression in primary pituitary cell cultures of adult male rats. Pituitary cells were treated for 24h with increasing concentrations of T3 (0.06-60 nM) or hydrocortisone (2.8 nM-2.8 microM). GHRH-R mRNA levels were assessed by ribonuclease protection assay. T3 caused a striking dose-dependent increase in GHRH-R mRNA, reaching levels 5.1 +/- 0.5 fold over controls (P < 0.001). Hydrocortisone also stimulated a marked dose-dependent increase in GHRH-R mRNA, reaching levels 5.6 +/- 0.7 fold over controls (P < 0.001). Combined treatment with both hormones did not cause further augmentation of GHRH-R mRNA levels. These data indicate that T3 and hydrocortisone act directly at the pituitary as potent regulators of GHRH-R gene expression.
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PMID:Thyroid hormone and glucocorticoid regulation of pituitary growth hormone-releasing hormone receptor gene expression. 907 92

Degenerate oligonucleotides were designed on the basis of conserved amino acid sequences in the DNA binding domains of the ecdysone receptors from Drosophila melanogaster (DmEcR) and Chironomus tentans (CtEcR). Using these oligonucleotides a fragment encoding part of the DNA binding domain of the Lucilia cuprina ecdysone receptor (LcEcR) was amplified by polymerase chain reaction (PCR) from genomic DNA and cloned. This cloned fragment was used to screen a cDNA library which was prepared from Lucilia larvae at the late third instar. A full-length LcEcR gene was isolated within a 3336 bp cDNA clone. The conceptually translated amino acid sequence of this open reading frame (757 amino acids) contained all five domains typical of a steroid hormone receptor. Alignment comparisons and phylogenetic analyses indicated that LcEcR most closely resembled the B1 isoform of DmEcR relative to other known insect steroid receptors, including six insect EcRs. An antisense RNA probe specific for the 3' end of LcEcR was used in ribonuclease protection assays to detect significant levels of LcEcR mRNA in embryos, late third instar larvae, pupae and adult females during Lucilia development. This pattern parallels the pattern of expression observed for DmEcR mRNAs during Drosophila development. The LcEcR gene was engineered for expression in mammalian cells, and we now report that the cloned LcEcR is functional and can act as an ecdysteroid-dependent transcription factor in mammalian cells.
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PMID:Cloning and characterization of LcEcR: a functional ecdysone receptor from the sheep blowfly Lucilia cuprina. 930 90

The peroxisome proliferator activated receptor alpha (PPAR) is a member of the steroid/hormone receptor superfamily that mediates the peroxisome proliferator-dependent transcriptional activation of genes encoding several peroxisomal and microsomal enzymes as well as peroxisome proliferation. Human liver is refractory to the pathological effects of peroxisome proliferators that are seen in mice. With the use of RNase protection assays, the ratio of hepatic PPAR alpha mRNA to beta-actin mRNA was found to be 1 order of magnitude lower in humans than that observed in mice. In addition, the isolation of human cDNA for PPAR alpha that does not encode a functional PPAR because it lacks exon 6 as a result of alternate RNA splicing suggested that this process might also diminish the expression of PPAR alpha. RNase protection analysis of total RNA revealed the presence of splice variants lacking exon 6 at significant levels in all 10 human liver samples examined. Supershift analysis using the CYP4A6-Z peroxisome proliferator response element and antisera specific for PPAR alpha revealed easily detectable amounts of PPAR alpha DNA binding activity in mouse liver lysates, whereas human liver lysates contained > 10-fold lower amounts of PPAR alpha DNA binding activity. In contrast to mouse lysates, the amount of PPAR alpha binding in human lysates was generally less than that of other unidentified proteins. These results suggest that although humans retain the coding potential for a functional receptor, the low levels of PPAR alpha expression in liver may be insufficient to compete effectively with other proteins that bind to peroxisome proliferator response elements.
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PMID:Peroxisome proliferator activated receptor-alpha expression in human liver. 944 28

Ethylene perception in plants is co-ordinated by multiple hormone receptor candidates sharing sequence commonalties with prokaryotic environmental sensor proteins known as two-component regulators. Two tomato homologs of the Arabidopsis ethylene receptor ETR1 were cloned from a root cDNA library. Both cDNAs, termed LeETR1 and LeETR2, were highly homologous to ETR1, exhibiting approximately 90% deduced amino acid sequence similarity and 80% deduced amino acid sequence identity. LeETR1 and LeETR2 contained all the major structural elements of two-component regulators, including the response regulator motif absent in LeETR3, the gene encoding tomato NEVER RIPE (NR). Using RNase protection analysis, the mRNAs of LeETR1, LeETR2 and NR were quantified in tissues engaged in key processes of the plant life cycle, including seed germination, shoot elongation, leaf and flower senescence, floral abscission, fruit set and fruit ripening. LeETR1 was expressed constitutively in all plant tissues examined. LeETR2 mRNA was expressed at low levels throughout the plant but was induced in imbibing tomato seeds prior to germination and was down-regulated in elongating seedlings and senescing leaf petioles. NR expression was developmentally regulated in floral ovaries and ripening fruit. Notably, hormonal regulation of NR was highly tissue-specific. Ethylene biosynthesis induced NR mRNA accumulation in ripening fruit but not in elongating seedlings or in senescing leaves or flowers. Furthermore, the abundance of mRNAs for all three LeETR genes remained uniform in multiple plant tissues experiencing marked changes in ethylene sensitivity, including the cell separation layer throughout tomato flower abscission.
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PMID:Differential regulation of the tomato ETR gene family throughout plant development. 972 82

Regulation of GH-releasing hormone receptor (GHRH-R) messenger RNA (mRNA) expression was studied, with the ribonuclease protection assay, in the fetal rat pituitary gland and in MtT-S clonal cells. GHRH-R mRNA was first detected on embryonic day (E)19 and increased rapidly thereafter, to reach a maximum at E21. Incubation of E17 or E18 pituitaries with 50 nM dexamethasone (DEX), a synthetic glucocorticoid, induced GHRH-R mRNA expression, suggesting that glucocorticoids play a pivotal role in the developmental expression of this mRNA. In E19 pituitaries, 24 h treatment with DEX increased GHRH-R mRNA by 60%, and GH mRNA by 76%, but did not affect pit-1 mRNA level, suggesting that the effect of DEX is specific for expressions of GH mRNA and GHRH-R mRNA. The accumulation of GHRH-R mRNA by DEX was time dependent, and it was slightly enhanced by the protein synthesis inhibitor, puromycin (100 microM). In MtT-S cells (a pituitary cell line established from an estrogen-induced tumor), DEX induced GHRH-R mRNA expression within 2 h in a dose-dependent manner. This induction was augmented by puromycin (100 microM) or cycloheximide (3.5 microM). However, the RNA synthesis inhibitor Actinomycin D (1 microM) completely inhibited GHRH-R mRNA accumulation in response to either DEX or DEX plus puromycin, suggesting that glucocorticoids induce GHRH-R mRNA mainly through stimulation of mRNA transcription. These results suggest: that GHRH-R mRNA accumulation in the fetal pituitary gland of rats normally occurs at E19, probably because of the direct action of glucocorticoids on the pituitary gland, to stimulate GHRH-R mRNA transcription; and that the expression of glucocorticoid receptors is an important event in GH cell development in rats. Accordingly, immunocytochemical results suggest an increase in glucocorticoid receptors in immature GH cells between E17 and E18. The present results also imply that MtT-S cells may be a good model in which to further study the molecular mechanisms of the regulation of GHRH-R gene expression.
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PMID:Regulation of growth hormone-releasing hormone receptor messenger ribonucleic acid expression by glucocorticoids in MtT-S cells and in the pituitary gland of fetal rats. 1034 67


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