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)

Heart failure in humans is characterized by alterations in myocardial adrenergic signal transduction, the most prominent of which is down-regulation of beta 1-adrenergic receptors. We tested the hypothesis that down-regulation of beta 1-adrenergic receptors in the failing human heart is related to decreased steady-state levels of beta 1 receptor mRNA. Due to the extremely low abundance of beta 1 receptor mRNA, measurements were possible only by quantitative polymerase chain reaction (QPCR) or by RNase protection methods. Because the beta 1 receptor gene is intronless and beta 1 receptor mRNA abundance is low, QPCR yielded genomic amplification in total RNA, and mRNA measurements had to be performed in poly (A)(+)-enriched RNA. By QPCR the concentration of beta 1 receptor mRNA varied from 0.34 to 7.8 x 10(7) molecules/microgram poly(A)(+)-enriched RNA, and the assay was sensitive to 16.7 zeptomol. Using 100-mg aliquots of left ventricular myocardium obtained from organ donors (nonfailing ventricles, n = 12) or heart transplant recipients (failing ventricles, n = 13), the respective beta 1 mRNA levels measured by QPCR were 4.2 +/- 0.7 x 10(7)/micrograms vs. 2.10 +/- 0.3 x 10(7)/micrograms (P = 0.006). In these same nonfailing and failing left ventricles the respective beta 1-adrenergic receptor densities were 67.9 +/- 6.9 fmol/mg vs. 29.6 +/- 3.5 fmol/mg (P = 0.0001). Decreased mRNA abundance in the failing ventricles was confirmed by RNase protection assays in total RNA, which also demonstrated a 50% reduction in beta 1 message abundance. We conclude that down-regulation of beta 1 receptor mRNA contributes to down-regulation of beta 1 adrenergic receptors in the failing human heart.
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PMID:Reduced beta 1 receptor messenger RNA abundance in the failing human heart. 825 27

The number of beta 1-adrenergic receptor (beta 1AR) binding sites is decreased by chronic antidepressant treatments, including electroconvulsive seizure (ECS) and imipramine, whereas administration of agents that deplete norepinephrine (NE) increases the number of beta 1AR binding sites in cerebral cortex. The present study was carried out to examine the influence of these treatments on levels of beta 1AR mRNA in frontal cortex to study the molecular mechanisms that underlie the regulation of beta 1ARs in brain. Levels of beta 1AR mRNA were measured by RNase protection analysis using a riboprobe derived from rat beta 1AR cDNA, and the levels of beta AR binding were measured using the nonselective ligand [3H]CGP-12177. Studies to verify the specificity of the RNase protection assay revealed that the distribution of beta 1AR mRNA was in agreement with the reported distribution of beta 1AR ligand binding: Levels of beta 1AR mRNA were highest in cerebral cortex or frontal cortex, intermediate in neostriatum, hippocampus, lung, and heart, and lowest in cerebellum, kidney, and liver. Chronic ECS treatment (once daily for 10 days) significantly decreased levels of beta AR ligand binding and resulted in a corresponding, time-dependent down-regulation of beta 1AR mRNA levels in frontal cortex. However, imipramine administration regulated levels of beta 1AR mRNA in a biphasic manner, with treatments for 7-14 days increasing and treatments for 18-21 days decreasing levels of beta 1AR mRNA in frontal cortex. In contrast, levels of [3H]CGP-12177 ligand binding were decreased at all time points examined (3-21 days).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Regulation of beta 1-adrenergic receptor mRNA and ligand binding by antidepressant treatments and norepinephrine depletion in rat frontal cortex. 838 47

Adhesion of cells to extracellular matrix proteins is mediated, in large part, by transmembrane receptors of the integrin family. The identification of specific integrins expressed in early embryos is an important first step to understanding the roles of these receptors in developmental processes. We have used polymerase chain reaction methods and degenerate oligodeoxynucleotide primers to identify and clone Xenopus integrin alpha subunits from neurula-stage (stage 17) cDNA. Partial cDNAs encoding integrin subunits alpha 2, alpha 3, alpha 4, alpha 5, alpha 6 and an alpha IIb-related subunit were cloned and used to investigate integrin mRNA expression in early embryos by RNase protection assay and whole-mount in situ hybridization methods. Considerable integrin diversity is apparent early in development with integrins alpha 2, alpha 3, alpha 4, alpha 5 and alpha 6 each expressed by the end of gastrulation. Both alpha 3 and alpha 5 are expressed as maternal mRNAs. Zygotic expression of alpha 2, alpha 3, alpha 4 and alpha 6 transcripts begins during gastrulation. Integrin alpha 5 is expressed at relatively high levels during cleavage, blastula and gastrula stages suggesting that it may represent the major integrin expressed in the early embryo. We demonstrated previously that integrin beta 1 protein synthesis remains constant following induction of stage 8 animal cap cells with activin (Smith, J. C., Symes, K., Hynes, R. O. and DeSimone, D. W. (1990) Development 108, 289-298.). Here we report that integrin alpha 3, alpha 4 and alpha 6 mRNA levels increase following induction with 10 U/ml activin-A whereas alpha 5, beta 1 and beta 3 mRNA levels remain unchanged. Whole-mount in situ hybridization reveals that alpha 3 mRNAs are expressed by cells of the involuting mesoderm in the dorsal lip region of early gastrulae. As gastrulation proceeds, alpha 3 expression is localized to a stripe of presumptive notochordal cells along the dorsal midline. In neurulae, alpha 3 mRNA is highly expressed in the notochord but becomes progressively more restricted to the caudalmost portion of this tissue as development proceeds from tailbud to tadpole stages. In addition, alpha 3 is expressed in the forebrain region of later stage embryos. These data suggest that integrin-mediated adhesion may be involved in the process of mesoderm involution at gastrulation and the organization of tissues during embryogenesis.
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PMID:Integrin alpha subunit mRNAs are differentially expressed in early Xenopus embryos. 840 28

The expression of eighteen different voltage-activated potassium channel genes in rat sympathetic ganglia was quantitatively analysed using an RNase protection assay. Eleven alpha-subunit genes and two beta-subunit genes were expressed in sympathetic ganglia. The relative level of potassium channel mRNA expression was compared between the superior cervical ganglion (SCG) and two preverteabral sympathetic ganglia, the coeliac ganglion (CG) and the superior mesenteric ganglion (SMG). Four mRNAs were differentially expressed: Kv1.2, Kv1.4, Kv2.2 and Kv beta 1. Transcripts from all four genes were more abundant in the prevertebral ganglia. From comparisons with previous electrophysiological studies it was concluded that genes encoding the channels underlying the M-current and D2-current, which are both prominent in sympathetic neurons, have yet to be identified. It was also concluded that members of the Kv4 family are likely to underlie the low-threshold A-current in sympathetic neurons.
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PMID:Potassium channel mRNA expression in prevertebral and paravertebral sympathetic neurons. 871 62

In human heart failure beta-adrenergic receptors are downregulated which contributes to the reduced responsiveness to positive inotropic beta-agonists in the diseased heart. The present study addressed the question whether the number of beta-adrenergic receptors in the failing human heart is regulated at the level of the mRNA and whether the absolute steady-state levels of subtype-specific mRNAs mirror the expression of receptor-subtype proteins in human heart. In a collaborative effort, two different and independent methods, performed in two independent laboratories, reverse transcription followed by polymerase chain reaction (RT-PCR) and RNase protection assays, were used to determine the absolute steady-state levels of beta 1- and beta 2-adrenergic receptor mRNAs in control (NF) and in failing human hearts. As determined by quantitative RT-PCR the beta 1-mRNA was significantly reduced from 0.98 +/- 0.12 (n = 10) to 0.49 +/- 0.11 pg/microgram total RNA in dilated cardiomyopathy (dCMP, n = 7) and to 0.40 +/- 0.11 pg/microgram total RNA in ischemic cardiomyopathy (iCMP, n = 8). The steady-state levels of mRNA specific for beta 2-adrenergic receptors also tended to be decreased but without reaching significance (NF: 0.16 +/- 0.05, dCMP: 0.11 +/- 0.03, iCMP: 0.13 +/- 0.04 pg/microgram total RNA). RNase protection assays revealed similar values. beta 1-mRNA was found to be significantly reduced from 1.22 +/- 0.22 in NF (n = 10) to 0.63 +/- 0.14 pg/microgram total RNA in dCMP (n = 5) and to 0.52 +/- 0.1 pg/microgram total RNA in iCMP (n = 8). The beta 2-mRNA also tended to be lower in dCMP and in iCMP as compared to NF but again without reaching significance (NF: 0.14 +/- 0.02, dCMP: 0.099 +/- 0.02, iCMP 0.107 +/- 0.02 pg/microgram total RNA). This is the first study to demonstrate in parallel by two different methods performed independently in two laboratories that the ratio of beta 1- and beta 2-adrenergic receptor densities in the left ventricle of the normal human heart of about 80/20 is closely related to the absolute steady state concentrations of their specific mRNA. In addition, the magnitude of the decrease in mRNA-levels of beta 1- and beta 2-adrenergic receptors in the failing human heart closely correlates with the decrease of the respective receptor proteins. These data suggest that the predominant regulation of beta-adrenergic receptors occurs at the mRNA level.
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PMID:Differential regulation of mRNA specific for beta 1- and beta 2-adrenergic receptors in human failing hearts. Evaluation of the absolute cardiac mRNA levels by two independent methods. 874 9

In order to provide evidence for a potential role of heterotrimeric GTP-binding proteins in the transduction of developmental signals, we prepared cDNAs from Xenopus laevis embryos and looked for fragments amplified between primers located in conserved sequences of the different subtypes of beta subunit. Using the amplified fragment as a probe, we cloned a member of the beta subunit family. The deduced protein sequence of the amphibian cDNA is highly homologous to the beta 1 subtype and, accordingly, we have named the Xenopus gene XG beta 1. In situ hybridization and RNase protection assay revealed that XG beta 1 mRNA is confined to the animal hemisphere of the mature oocyte. This localization of XG beta 1 mRNA is established at stage V during oogenesis. Following fertilization, the maternal mRNAs cosegregate with animal cells during cleavage stages. At gastrulation, transcripts are expressed in the dorsal ectoderm layer that will give rise to the central nervous system. Thus, XG beta 1 mRNA belongs to the small family of localized maternal mRNAs; as a transducing protein, its restriction to a subset of embryonic cells could mediate the distinct responsiveness which contributes to the patterning of the embryo.
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PMID:The mRNA encoding a beta subunit of heterotrimeric GTP-binding proteins is localized to the animal pole of Xenopus laevis oocyte and embryos. 895 92

RC-RNase is a pyrimidine-guanine sequence-specific ribonuclease and a sialic-acid-binding lectin purified from Rana catesbeiana (bullfrog) oocytes. This 111-amino acid protein exhibits cytotoxicity toward several tumor cell lines. In this paper we report the assignments of proton NMR resonances and the identification of the secondary structure deduced from NOE constraints, chemical shift index, 3JNH alpha and amide proton exchange rates. The protein was directly isolated from bullfrog oocytes; we were able to assign all but five of the amino acid backbone protons of the unlabeled protein by analyzing a large set of two-dimensional proton NMR spectra obtained at several temperatures and pH conditions. Our results indicate that the structure of RC-RNase is dominated by the presence of two triple-stranded antiparallel beta-sheets and three alpha-helices, similar to those of the pyrimidine family ribonucleases. Two sets of resonances were observed for 11 amide protons and 8 alpha-protons located in the loop-1 region, an alpha 2 helix, and three beta-strands, (beta 1, beta 3 and beta 4), suggesting the presence of nonlocalized multiple conformations for RC-RNase.
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PMID:The secondary structure of a pyrimidine-guanine sequence-specific ribonuclease possessing cytotoxic activity from the oocytes of Rana catesbeiana. 895 20

RT4-B is one of several cell lines derived from a multipotent stem cell line, RT4-AC, which originated from a rat peripheral neurotumor. Based on Northern blot and ribonuclease protection experiments, RT4-B8 cells have been proposed to express rat cardiac Na channel mRNA as the major isoform. We report here direct electrophysiological evidence that the expressed voltage-gated Na channels in the RT4-B8 cell line are of the cardiac phenotype with no evidence for subpopulations expressing other Na channel isoforms. Current activation half point (conductance) was -41 +/- 5 mV (n = 7) and the steady-state voltage-dependent availability half point was -89 +/- 1 mV. As expected for cardiac Na channels, the half concentration of block for tetrodotoxin block was 0.74 microM, for saxitoxin (STX) was 0.15 microM, and for the class 2B divalent cation Cd2+ was 67 microM. Block was well described by single-site dose-response relationships with no indication of a subpopulation with "neuronal" affinity. Single-channel conductance (140 mM Na+) was 10 pS and predicted the average number of channels open at peak Na current to be 3 channels/microns2. [3H]STX binding data were also consistent with a single population of low-affinity STX binding sites and predicted channel density to be 11 sites/microns2. No inwardly or outwardly rectifying K or Ca currents were detected electrophysiologically, although in some cells a small time-independent Cl current was detected. Reverse transcription-polymerase chain reaction of mRNA isolated from RT4-B8 cells demonstrated the presence of rat cardiac (rH1) and brain IIa alpha-subunit mRNA, as well as mRNA for the Na channel beta 1-subunit. Northern blot analysis confirmed the predominance of the rat cardiac Na mRNA compared with brain IIa. The beta 1-subunit mRNA levels were significantly lower than those detected in rat brain and heart mRNA but were comparable to the low level of beta 1-subunit mRNA detected in isolated rat ventricular myocytes.
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PMID:Cardiac sodium channels expressed in a peripheral neurotumor-derived cell line, RT4-B8. 896 55

IL-12 has been shown to play a central role in cell-mediated inflammatory reactions through direct activation of T cells and NK cells. IL-12 also strongly influences humoral immunity but these effects have been thought to be indirect and caused by intermediary cytokines. Using flow cytometry, we now show that IL-12 directly interacts with B cells. Freshly isolated murine peritoneal B-1 and conventional B lymphocytes bound IL-12, but splenic B cells failed to react unless first stimulated with lipopolysaccharide. All murine B cell sources were found to express IL-12R beta 1 subunit transcripts as detected by PCR and RNase protection assays. IL-12 binding was also detected on phytohemagglutinin-stimulated human T cell blasts and Staphylococcus aureusl IL-2-stimulated B cell blasts but not on freshly isolated peripheral blood lymphocytes. Similarly, IL-12 directly bound to the human SKW6.4 Burkitt's B cell lymphoma line. In all cases positive staining was ablated by omitting IL-12 from the procedure, showing that it was not due to detection of endogenous IL-12. These findings indicate that B cells represent another major target for IL-12 in addition to T and NK cells, and that IL-12 can directly affect humoral immunity.
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PMID:Direct binding of IL-12 to human and murine B lymphocytes. 898 80

Several neuronal nicotinic acetylcholine receptor (AChR) genes are expressed in chick skeletal muscle during development. One of the most abundantly expressed is alpha 7, which produces a protein capable of binding alpha-bungarotoxin and is physically distinct from muscle AChRs containing the alpha 1 gene product. We show here that the alpha 7-containing species in muscle is indistinguishable pharmacologically from alpha 7-containing AChRs in neurons. In addition, immunologic analysis with subunit-specific muscle antibodies shows that the alpha 7-containing species in muscle lacks the beta 1 and delta muscle AChR gene products as it does the alpha 1. RNase protection experiments measuring alpha 7 mRNA levels indicate that the alpha 1 and alpha 7 genes may, in part, be subject to similar kinds of regulation in the tissue. Surgical denervation of leg muscle in newly hatched chicks caused a small and transient increase in alpha 7 mRNA after 8 days, while alpha 1 transcripts underwent a large and sustained increase in number. Similarly, treating myotube cultures with tetrodotoxin caused a modest increase in alpha 7 transcript levels and a large increase in alpha 1. Calcitonin gene-related peptide (CGRP) increased both kinds of transcripts in myotube cultures equally as did treatment with 8-bromo-cyclic AMP; CGRP is thought to work via a cyclic AMP-dependent pathway in muscle. In at least one respect, however, alpha 7 expression in muscle differs qualitatively from that of alpha 1: AChR-inducing activity (ARIA) increased alpha 1 mRNA levels in culture while slightly depressing alpha 7 mRNA levels. The regulatory pattern of alpha 7 expression in muscle may combine features of both alpha 7 expression in neurons and alpha 1 expression in muscle.
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PMID:Neuronal-type acetylcholine receptors and regulation of alpha 7 gene expression in vertebrate skeletal muscle. 898 64


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