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

---

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

Leukemia inhibitory factor (LIF) and ciliary neurotrophic factor (CNTF) have previously been shown to regulate neuronal choice of neurotransmitter. In this present study, these factors were shown to specifically and differentially regulate levels of both muscarinic (subtypes m1, m2, m3, m4, and m5) and substance P receptor (SPR) mRNAs in sympathetic neurons of the rat superior cervical ganglion (SCG) using solution hybridization/RNase protection analysis. In vivo, neonatal rat SCG expressed predominantly m2 (10.31 +/- 0.43 pg mRNA/micrograms total RNA) and some m1 (1.54 +/- 0.84 pg/microgram) muscarinic receptor mRNA, which increased developmentally to adult levels (m2 mRNA levels being 60% higher than those in neonates). By contrast, m3, m4, and m5 subtype mRNAs were much less abundant at all time points measured. A similar developmental regulation was found in dissociated SCG neurons in vitro. After 16 days in culture, m2 mRNA increased 334% to 15.76 +/- 0.68 pg/microgram, while m1 mRNA changed little (2.03 +/- 1.00 pg/microgram). However, LIF or CNTF treatment (5 ng/ml, 14 days) in sister cultures completely blocked this developmental increase. Further, LIF treatment blocked the normal muscarinic receptor-mediated increase in intracellular calcium (fura-2 imaging), indicating a functional change in receptor phenotype. By contrast, levels of SPR mRNA, which were low in untreated cultures (0.037 +/- 0.025 pg SPR mRNA/microgram total RNA), were elevated by LIF or CNTF treatment, to 0.866 +/- 0.034 pg/microgram and 0.662 +/- 0.148 pg/microgram, respectively. These observations indicate that muscarinic and SPR receptor expression are differentially regulated by the same factors in SCG neurons and that neuronal choice of receptor phenotype may be, at least in part, specifically regulated by cytokines/growth factors in the cellular milieu.
...
PMID:mRNAs encoding muscarinic and substance P receptors in cultured sympathetic neurons are differentially regulated by LIF or CNTF. 751 57

Five muscarinic receptor genes (m1-m5) that encode distinct muscarinic receptor subtypes have been cloned. Because of their structural homology and pharmacological similarity, ligand binding probes currently available do not clearly distinguish among the subtypes. To obtain a clear distribution within the CNS of molecularly defined muscarinic receptor subtypes, seven brain regions were examined for the expression of the respective mRNAs. The most sensitive method for detecting mRNA is through amplification of the respective cDNAs. Brain regions were obtained from male Wistar rats, and total RNA was isolated. The isolates were extensively treated with RNase-free DNase to remove any residual genomic DNA. Total RNA (1 microgram) was reverse-transcribed using random primers and reverse transcriptase. The resulting cDNA was amplified using a thermal cycler, and the polymerase chain reaction (PCR)-amplified products were analyzed by gel electrophoresis containing ethidium bromide and visualized with fluorescent illumination. PCR-amplified samples were also injected directly onto an HPLC anion exchange column and quantified by UV detection. Each of the five muscarinic subtypes was found in every brain region examined. The m1 subtype was most abundant in cortex and gradually declined in content caudally to the spinal cord. The m2 subtype was most abundant in thalamus-hypothalamus and ponsmedulla. The m4 subtype was found in greatest amount in the striatum, whereas m3 and m5 were expressed consistently throughout the CNS. The combination of RT-PCR and HPLC provides a rapid and sensitive method for quantifying the expression of mRNA coding for all five muscarinic receptor subtypes derived from the CNS.
...
PMID:m1-m5 muscarinic receptor distribution in rat CNS by RT-PCR and HPLC. 751 60

The regulation of m4 muscarinic acetylcholine receptor mRNA expression by receptor activation was studied in N1E-115 neuroblastoma and AtT-20 pituitary cells that endogeneously express the m4 muscarinic receptor. Receptor concentration was measured by binding of the muscarinic receptor radioligand [3H]quinuclidinyl benzilate, and RNA-RNA solution hybridization/RNase protection assay with a m4 receptor-specific [32P]-cRNA probe was used to evaluate the levels of receptor mRNA. Treatment of both cell lines with a receptor-saturating concentration of the agonist carbachol decreased receptor number. However, there was no change in steady-state levels of m4 mAChR mRNA in both cell lines. Determination of mRNA stability in the presence of the transcription blocker actinomycin D revealed that carbachol treatment increased half-life of receptor mRNA in N1E-115 cells, but not in AtT-20 cells, suggesting that receptor activation can regulate m4 receptor mRNA stability dependently on cell type. Analysis of receptor degradation kinetics in the presence of the protein synthesis inhibitor cycloheximide showed that receptor down-regulation in N1E-115 and AtT-20 cells is sufficiently accounted for by increased receptor degradation. These results indicate than m4 muscarinic receptor down-regulation is substantially different from that of the muscarinic receptor subtypes m2 and m3 which is reported to be associated with agonist-induced reduction in receptor mRNA.
...
PMID:Agonist-induced down-regulation of the m4 muscarinic acetylcholine receptor occurs without changes in receptor mRNA steady-state levels. 787 Jan 90

Prior studies have suggested that heart expresses only the M2 isoform of the muscarinic receptor (Peralta, E.G., Ashkenazi, A., Winslow, J.W., Smith, D.H., Ramachandran, J., and Capon, D.J. (1987) EMBO J. 6, 3923-3929). Tietje and Nathanson (Tietje, K.M., and Nathanson, N. M. (1991) J. Biol. Chem. 266, 17382-17387) have recently demonstrated that the chick heart may be unique since it expresses both the M2 and M4 isoforms of the muscarinic receptor. In this study, in order to determine whether other isoforms of the muscarinic receptor were present in the chick heart, a chick M3 muscarinic receptor receptor was cloned, characterized, and its expression in chick tissues determined. Using a human M3 muscarinic receptor cDNA as a probe, a 2.4-kilobase pair cDNA was isolated from a chick brain cDNA library which contained an open reading frame coding for a 639 amino acid protein. This protein demonstrated an 87 and 86% homology to the human and rat M3 muscarinic receptor, respectively. Chinese hamster ovary (CHO-GRA) cells were stably transfected with the chick M3 muscarinic receptor and one clone (CHO-CM3) expressed the M3 receptor, as measured by the binding of quinuclidinly benzilate at 116 +/- 14 (+/- S.E., n = 3) fmol/mg protein with a Kd of 76 +/- 17 pM. This receptor demonstrated a rank order of potency for muscarinic antagonist binding characteristic for the M3 receptor: with high affinity binding for hexahydrosiladifenidol, Kd: 16 +/- 2 nM (+/- S.E., n = 3); intermediate affinity for pirenzepine, Kd: 383 +/- 47 nM, and low affinity for methoctramine, Kd: 533 +/- 185 nM (+/- S.E., n = 3). Carbamylcholine stimulation of CHO-CM3 cells resulted in a 1.6-fold increase in cyclic AMP accumulation and a 3.5-fold increase in a pertussis toxin-insensitive inositol phosphate release. These data demonstrate that the chick M3 muscarinic receptor has the properties characteristic of M3 receptors from other species. RNase protection studies demonstrated the presence of M3 muscarinic receptor mRNA in the brain, atria, and ventricle of chicks 17 days in ovo. Hence, the chick heart appears to have the unique capacity to express mRNAs coding not only for the M2 and M4 muscarinic receptors but also for the M3 muscarinic receptor.
...
PMID:A novel M3 muscarinic acetylcholine receptor is expressed in chick atrium and ventricle. 792 87

Growth of chick atrial cells in medium supplemented with lipoprotein-depleted serum has been shown to result in an increase in total cell cholesterol, and an increase in the negative chronotropic response to muscarinic stimulation in parallel with an increase in levels of muscarinic receptors and the G-protein alpha-subunits alpha i and alpha o (Haigh, L. S., Leatherman, G. F., O'Hara, D. S., Smith, T. W., and Galper, J. B. (1988) J. Biol. Chem. 263, 15608-15618). In this study we determined whether growth of chick ventricular cells in medium supplemented with lipoprotein depleted serum could alter levels of muscarinic receptors and G-protein alpha-subunits and induce a negative chronotropic response to muscarinic stimulation. We further determined whether levels of mRNA coding for muscarinic receptors, G-proteins, and the acetylcholine-sensitive K+ channel were coordinately regulated. Growth of embryonic chick ventricular cells from hearts 14 days in ovo in medium supplemented with lipoprotein depleted serum resulted in a 21 +/- 5% (n = 3, +/- S.E.) increase in muscarinic receptor number as demonstrated by [3H]quinuclidinyl benzilate binding and a 4.7 +/- 1.0 (+/- S.E., n = 4)-fold increase in G alpha i2 as demonstrated by Western blot analysis. These changes in receptor and G-protein were associated with a coordinate increase in levels of mRNA coding for the M2 muscarinic receptor, G alpha i2 and the acetylcholine sensitive K+ channel as determined by RNase protection. These increases were reversed by addition of 30 microM mevinolin, an inhibitor of HMG-CoA reductase activity. Carbamylcholine (0.1 mM) had no effect on beat rate in ventricular cells grown in medium supplemented with fetal calf serum. Cells grown in medium supplemented with lipoprotein depleted serum demonstrated a 40 +/- 8% (+/- S.E., n = 10, p < 0.0001) decrease in beat rate in response to 0.1 mM carbamylcholine which was reversed by the addition of 30 microM mevinolin. These data suggest that, during growth in medium supplemented with lipoprotein depleted serum, a component of the cholesterol biosynthetic pathway plays a role in the coordinate induction of mRNAs coding for receptors, G-proteins, and an effector (ion channel) that results in the induction of a parasympathetic response in the ventricular cell characteristic of the atrial phenotype.
...
PMID:Low density lipoproteins induce parasympathetic responsiveness in embryonic chick ventricular myocytes in parallel with a coordinate increase in expression of genes coding for the M2 muscarinic receptor, G alpha i2, and the acetylcholine-sensitive K+ channel. 798 91

Studies involving carbachol (100 microM) treatment of cerebellar granule cells for 1, 3, 6, 9, 12 and 24 hr show a decrease in the mRNA encoding for the muscarinic m2 receptor. The response was transient, decreasing m2 mRNA by 25 to 50% in 6 and 9 hr, respectively. The data presented in this work were quantified by ribonuclease protection assay, using a [32P]-cRNA probe corresponding to nucleotide +1138 to 1650 of the rat m2 muscarinic receptor. Because cerebellar granule cells express muscarinic m2 and m3 receptors, we tested whether the carbachol-mediated decrease in m2 mRNA resulted from a homologous or heterologous activation of muscarinic receptors. At a 1 microM concentration, methoctramine specifically blocked the muscarinic m2 receptor and reversed carbachol's action. These data suggested that carbachol acts via a possible homologous activation of muscarinic m2 receptors. The half-life of the receptor mRNA measured in the presence of actinomycin D with and without carbachol were similar. Because carbachol treatments decrease the steady-state levels of m2 mRNA without changing the half-life of the message, we suggest that a carbachol treatment induces a decrease in the transcription of the gene for the muscarinic m2 receptor.
...
PMID:Characterization of a decrease in muscarinic m2 mRNA in cerebellar granule cells by carbachol. 847 26

Relaxation of the trabecular smooth muscle, which is necessary for penile erection, is controlled locally by neurotransmitters and vasoactive agents. The goal of this study was to identify and characterize muscarinic acetylcholine receptor (mAChR) subtypes expressed in cultured human corpus cavernosum smooth muscle cells (HCC SMC). Binding analysis with L-[benzilic-4,4'-3H(N)]quinuclidinyl benzilate ([3H]QNB) demonstrated the expression of specific muscarinic receptor binding sites in HCC SMC. Analysis of total RNA isolated from whole corpus cavernosum tissue and smooth muscle cells, by RNase protection assays, demonstrated the expression of mRNA transcripts for m1, m2, m3, and m4 mAChR subtypes in whole tissue and m2 and m4 subtypes in cultured cells. In situ hybridization with specific m2 and m4 probes further confirmed the expression of m2 and m4 mRNA transcripts in cultured cells. Carbachol (CCh), a nonselective cholinergic agonist, inhibited cAMP synthesis at low concentrations (0.1-1 microM) and stimulated cAMP synthesis at high concentrations (100 microM), in cultured HCC SMC. CCh (100 microM) further augmented forskolin (FSK), isoproterenol (ISO), and prostaglandin E1 (PGE1)-induced cAMP synthesis. These observations suggest that, in vivo, in HCC, ACh may activate m3 mAChR subtypes on endothelial cells or m2 and m4 subtypes on the SMC. Although m2 and m4 are thought to inhibit adenylate cyclase (AC), the augmentation of cAMP synthesis by high concentrations of CCh in SMC suggests an alternative mechanism of coupling to G-proteins that stimulates AC activity. These studies show that HCC tissue expresses different subtypes of mAChR (m1, m2, m3, and m4), whereas cultured HCC SMC express m2 and m4 subtypes. It is suggested that m2 and m4 receptor subtypes may play an important role in maintaining trabecular smooth muscle tone in vivo. The augmentation of FSK-, ISO, and PGE1-induced cAMP synthesis by CCh suggests possible development of a multidrug therapeutic approach to treatment of erectile dysfunction.
...
PMID:Expression of functional muscarinic acetylcholine receptor subtypes in human corpus cavernosum and in cultured smooth muscle cells. 872 95

Quantitative RNase protection assays were performed to determine the levels of muscarinic receptor subtype (m1-m5) mRNAs in rat hippocampi. Results showed that the m1, m3, and m4 subtype mRNAs were expressed at relatively high levels, but the levels of the m2 and m5 subtype were very low. Three weeks following aspiration lesions of the fimbria-fornix to produce cholinergic denervation of the hippocampus, non-M1 receptors (non-pirenzepine displaceable [3H]quinuclindinyl benzilate binding sites) in the hippocampus were increased significantly, which correlated with increases in the levels of hippocampal m3 and m4 receptor mRNAs (m3: +24% and m4: +41%). These findings indicate that multiple muscarinic receptor subtypes are expressed in the hippocampus with the m3 and m4 subtypes predominantly postsynaptic to the septohippocampal cholinergic terminals.
...
PMID:Differential regulation of expression of rat hippocampal muscarinic receptor subtypes following fimbria-fornix lesion. 921

Five subtypes of the muscarinic receptor have been cloned from both the rat and human genomes. Although all five genes have the coding sequences in a single exon, their structures 5' of the initiation codon are largely uncharacterized, except for the M4 receptor. In the brain, muscarinic receptors mediate motor and memory function by interaction with their ligand acetylcholine. In addition, the M1 muscarinic subtype has been implicated in behavior, stress-adaptive cardiovascular reflexes, and blood pressure regulation. In the current study the M1 muscarinic receptor noncoding 5'-flanking region has been identified and characterized, including the promoter and two 5' noncoding exons located approximately 13-14 kb from the coding exon. Similar to the M4 muscarinic receptor gene the M1 promoter is GC-rich, contains no TATA box, but has two potential CAAT boxes and several putative binding sites for transcription factors such as SP1 and AP-1-3. The transcription initiation site was identified by RNase protection and primer extension. Promoter activity was confirmed in transient expression assays, using luciferase reporter constructs. A 0.89-kb fragment consisting of 480 bp of the promoter, exon 1, and part of intron 1 expressed luciferase activity in two M1 receptor-expressing cell lines (CCL-107 and CCL-147), whereas a longer fragment (1.5 kb) that extends into intron 2 demonstrated significantly increased luciferase activity. The constructs exhibited responses indicating the presence of functional glucocorticoid-, acute-phase-, and heat shock-responsive elements.
...
PMID:Identification and characterization of the rat M1 muscarinic receptor promoter. 1003 60

It is well known that chronic topical administration of cholinergic agonists results in a subsensitization in ciliary muscle-mediated increases in outflow facility and accommodation in monkey eyes in vivo. These physiologic changes are apparently mediated by the M3 subtype receptor. However, the nature of this subsensitization remains unclear. This study investigated the effect of the continuous presence of carbachol, a muscarinic agonist, on the expression of the muscarinic receptor subtype m3 and the binding of [3H]4-DAMP in cultured human ciliary muscle cells (H7CM). The H7CM cell line, derived from the ciliary muscle of a one-day-old human infant, was used in this study. Confluent monolayers were treated individually with 1 mM carbachol for 2, 6, 24 and 48 hours. The level of mRNA encoding muscarinic receptor subtype m3 was measured by RNase protection. For confirmation, a receptor binding assay was done using [3H]4-DAMP, a radioligand selective for M3 subtype receptors. At each timepoint, results were compared with untreated controls. Treatment with carbachol resulted in a down regulation ranging from 23.4% to 34.8% of m3 mRNA expression at all time points. All [3H]4-DAMP binding assay results also decreased, ranging from 24.5% to 31.0%.
...
PMID:Effect of continuous administration of a cholinergic agonist on [3H]4-DAMP binding and m3 mRNA expression in cultured human ciliary muscle cells. 1022 93


1 2 Next >>

---