Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.26.9 (ribonuclease)
 6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A major limitation to the use of rat hepatocytes in the study of drug metabolism and toxicity is the rapid loss of CYPs. We demonstrate that the culture of rat hepatocytes results in a rapid loss of liver-specific CYP2C11 mRNA and transcripts encoding the general housekeeping gene copper-zinc superoxide dismutase (CuZnSOD) as well as poly(A(+)) mRNA. These losses are accelerated by fibronectin, which has no effect on the transcription of CYP2C11 and CuZnSOD. However, fibronectin, an extracellular matrix protein involved in cell adhesion and spreading, induces ribonuclease (RNase) activity. Fibronectin also increases hepatocyte diameter and data are presented that cell spreading is involved in the loss of both CYP2C11 and CuZnSOD mRNAs. The use of functional blocking antibodies demonstrates that fibronectin is operating through its alpha(5)beta(1) integrin receptor and genistein, a tyrosine kinase inhibitor, prevents hepatocyte spreading, RNase induction, and CYP2C11 mRNA loss. Collectively, the data indicate that hepatocytes in vitro actively promote the extinction of their phenotype via the autocrine effects of fibronectin rather than the current consensus that they simply lose differentiated function, such as CYP2C11 expression, through the absence of extracellular matrix proteins. The substrate specificity of the ribonuclease induced is also considered.
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PMID:Fibronectin-mediated hepatocyte shape change reprograms cytochrome P450 2C11 gene expression via an integrin-signaled induction of ribonuclease activity. 1104 44

Gene expression can be examined with different techniques including ribonuclease protection assay (RPA), in situ hybridisation (ISH), and quantitative reverse transcription-polymerase chain reaction (RT/PCR). These methods differ considerably in their sensitivity and precision in detecting and quantifying low abundance mRNA. Although there is evidence that RT/PCR can be performed in a quantitative manner, the quantitative capacity of this method is generally underestimated. To demonstrate that the comparative kinetic RT/PCR strategy-which uses a housekeeping gene as internal standard-is a quantitative method to detect significant differences in mRNA levels between different samples, the inhibitory effect of heparin on phorbol 12-myristate 13-acetate (PMA)-induced-TGF-beta1 mRNA expression was evaluated by RT/PCR and RPA, the standard method of mRNA quantification, and the results were compared. The reproducibility of RT/PCR amplification was calculated by comparing the quantity of G3PDH and TGF-beta1 PCR products, generated during the exponential phases, estimated from two different RT/PCR (G3PDH, r = 0.968, P = 0.0000; TGF-beta1, r = 0.966, P = 0.0000). The quantitative capacity of comparative kinetic RT/PCR was demonstrated by comparing the results obtained from RPA and RT/PCR using linear regression analysis. Starting from the same RNA extraction, but using only 1% of the RNA for the RT/PCR compared to RPA, significant correlation was observed (r = 0.984, P = 0.0004). Moreover the morphometric analysis of ISH signal was applied for the semi-quantitative evaluation of the expression and localisation of TGF-beta1 mRNA in the entire cell population. Our results demonstrate the close similarity of the RT/PCR and RPA methods in giving quantitative information on mRNA expression and indicate the possibility to adopt the comparative kinetic RT/PCR as reliable quantitative method of mRNA analysis.
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PMID:Quantitation of TGF-beta1 mRNA in porcine mesangial cells by comparative kinetic RT/PCR: comparison with ribonuclease protection assay and in situ hybridization. 1143 5

The human translation termination factor 1 (ETF1) gene encodes a class-1 release factor, eRF1, which catalyses termination of protein synthesis at all three stop codons. In this report, we describe the functional organization of the 5'-region of the gene. Primer extension and ribonuclease protection mapping revealed three transcription start sites clustered within approximately 10 bp. DNase I-hypersensitive site analysis identified five hypersensitive sites, one of which was located downstream of the initiation start sites. We used transient expression assays to define the 5'-regulating regions and in vivo and in vitro footprinting analysis to identify potential cis-acting regulatory elements. A basal promoter, spanning nucleotides -210/+117, contained no TATA box but a putative initiator element (Inr) and multiple potential Sp1/Sp3 binding sites, and thus displayed some of the features of a housekeeping gene. An additional upstream promoter containing positive and negative regulatory elements also regulated ETF1 gene expression. Real-time quantitative RT-PCR analysis showed tissue-specific expression of ETF1 transcripts in mouse tissues. Our results are suggestive of a constitutive expression of the human ETF1 gene but with possible cell- and tissue-specific regulation.
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PMID:Promoter analysis of the human translation termination factor 1 gene. 1456 55

Helicobacter pylori are bacteria with substantial inter-strain variability and phylogenetic reconstructions of sequence data from the organism have common homoplastic sites. Although frequent recombination events have been proposed to contribute to the variation, the effects of nucleotide substitution rate heterogeneities on the reconstruction of H. pylori genealogies have not been studied. We analyzed the substitution pattern of a housekeeping gene, a homologue of the ribonuclease reductase gene (rnr), to characterize rate heterogeneities between 11 H. pylori isolates. Evidence of limited recombination was demonstrated by the Sawyer's runs test, but the homoplasy test and site-by-site compatibility tests indicated frequent recombination events. Within the 1935 nucleotide gene, 292 sites were polymorphic with an average pair-wise difference of 5.01%. Xia's distances for amino acids at non-synonymous codon substitution sites were smaller at homoplastic sites than at sites that were not homoplastic. Transitions were significantly more common among homoplastic than among non-homoplastic nucleotide substitutions. Simulations of evolution with or without recombination indicated the transition/transversion ratio is expected to be higher in homoplastic sites with no recombination. Despite evidence of recombination, analyses of the rnr genealogy does not show a random tree but rather base substitution behaviors characteristic of both recombination and substitution saturation at some sites. Analyses of sequences in the H. pylori multilocus sequence-typing database provided similar evidence for substitution saturation in multiple housekeeping genes.
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PMID:Rate heterogeneity in the evolution of Helicobacter pylori and the behavior of homoplastic sites. 1857 92

Ribonucleases belonging to the RNase T2 family are enzymes associated with the secretory pathway that are almost absolutely conserved in all eukaryotes. Studies in plants and vertebrates suggest they have an important housekeeping function in rRNA recycling. However, little is known about this family of enzymes in protostomes. We characterized RNase X25, the only RNase T2 enzyme in Drosophila melanogaster. We found that RNase X25 is the major contributor of ribonuclease activity in flies as detected by in gel assays, and has an acidic pH preference. Gene expression analyses showed that the RNase X25 transcript is present in all adult tissues and developmental stages. RNase X25 expression is elevated in response to nutritional stresses; consistent with the hypothesis that this enzyme has a housekeeping role in recycling RNA. A correlation between induction of RNase X25 expression and autophagy was observed. Moreover, induction of gene expression was triggered by oxidative stress suggesting that RNase X25 may have additional roles in stress responses. Phylogenetic analyses of this family in protostomes showed that RNase T2 genes have undergone duplication events followed by divergence in several phyla, including the loss of catalytic residues, and suggest that RNase T2 proteins have acquired novel functions. Among those, it is likely that a role in host immunosuppression evolved independently in several groups, including parasitic Platyhelminthes and parasitoid wasps. The presence of only one RNase T2 gene in the D. melanogaster genome, without any other evident secretory RNase activity detected, makes this organism an ideal system to study the cellular functions of RNase T2 proteins associated with RNA recycling and maintenance of cellular homeostasis. On the other hand, the discovery of gene duplications in several protostome genomes also presents interesting new avenues to study additional biological functions of this ancient family of proteins.
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PMID:Phylogenetic analyses and characterization of RNase X25 from Drosophila melanogaster suggest a conserved housekeeping role and additional functions for RNase T2 enzymes in protostomes. 2513 12

Bacillus pumilus ribonuclease (binase) was shown to be a promising antiviral agent in animal models and cell cultures. However, the mode of its antiviral action remains unknown. To assess the binase effect on intracellular viral RNA we have selected single stranded negative- and positive-sense RNA viruses, influenza virus, and rhinovirus, respectively, which annually cause respiratory illnesses and are characterized by high contagious nature, mutation rate, and antigen variability. We have shown that binase exerts an antiviral effect on both viruses at the same concentration, which does not alter the spectrum of A549 cellular proteins and expression of housekeeping genes. The titers of influenza A (H1N1pdm) virus and human rhinovirus serotype 1A were reduced by 40% and 65%, respectively. A preincubation of influenza virus with binase before infection significantly reduced viral titer after single-cycle replication of the virus. Using influenza A virus mini genome system we showed that binase reduced GFP reporter signaling indicating a binase action on the expression of viral mRNA. Binase reduced the level of H1N1pdm viral NP mRNA accumulation in A549 cells by 20%. Since the viral mRNA is a possible target for binase this agent could be potentially applied in the antiviral therapy against both negative- and positive-sense RNA viruses.
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PMID:Ribonuclease from Bacillus Acts as an Antiviral Agent against Negative- and Positive-Sense Single Stranded Human Respiratory RNA Viruses. 2854 65


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