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)

Hormones play a role in the regulation of gene expression by inducing changes in enzyme patterns in target cells mediated by the synthesis of specific RNA molecules. Erythropoiesis has been used as a system for studying the molecular mechanism of regulation of gene action by means of two hormones: erythropoietin and testosterone. Experiments designed to correlate the biochemical action of both hormones on rat marrow cells are herein reported. Both factors seems to act at different biochemical and citological levels. Erythropoietin triggers the erythropoietic process acting on the erythropoietin sensitive cells (ESC), in which the hormone induces the synthesis of a high molecular weight RNA, which is the precursor of a functional 9 S messenger RNA. Testosterone seems to act on polychromatophilic erythroblasts, in which the synthesis of ribosomal RNA or its precursor is stimulated. The steroid enhances the nuclear ribonuclease activity, which could represent a control mechanism for the processing (maturation) of high molecular weight RNAs. The incorporation of 3H-GTP and 3H-UTP into RNA by isolated rat bone marrow nuclei is stimulated by erythropoietin and testosterone. Using alpha-amanitine and different ionic strength conditions it was found that erythropoietin enhances preferentially RNA polymerase II activity while testosterone increases RNA polymerase I activity. It is postulated that erythropoietin and testosterone act synergically to create the biochemical machinery for hemoglobin synthesis, the macromolecule that characterizes the erythropoietic process.
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PMID:Hormonal control of gene expression: differential activation of rat bone marrow RNA polymerases by erythropoietin and testosterone. 9 87

Treatment of neuroblastoma cells with dibutyryl-adenosine 3':5'-monophosphate or adenine induced axon formation and a three-fold increase in the polyadenylate, poly(A), content of the polysomal mRNA. The extracted poly(A) contained 90% adenylic acid and showed a mobility of 6--7 S in dodecylsulfate-polyacrylamide gel electrophoresis. Treatment with dibutyryl-adenosine 3':5'-monophosphate or adenine, also induced a 4--6 fold increase in a nuclear enzymic activity that incorporated [3H]ATP to an acid-insoluble polymer in a cell-free system. This polymer, like poly(A) extracted from the polysomal mRNA, was bound at high salt concentration to nitrocellulose filters. [3H]ATP incorporation was Mg2+-dependent, sensitive to ribonuclease and EDTA and resistant to deoxyribonuclease and actinomycin D. There was no incorporation of [3H]UTP or [3H]dTTP and addition of TUP, CTP and GTP did not increase the incorporation of [3H]ATP. 5-Bromodeoxyuridine induced axon formation of neuroblastoma cells and poly(A) polymerase activity, without increasing the poly(A) content in the polysomal mRNA. The results indicate that induction of axon formation of neuroblastoma cells is associated with an increase in the activity of poly(A) polymerase. It is suggested that the induction of this enzyme may be generally involved in cell differentiation.
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PMID:Induction of polyadenylate polymerase and differentiation in neuroblastoma cells. 17 99

Escherichia coli B infected with T4 phage ghosts at 10 mM Mg2+ regains its protein synthesizing activity upon addition of ATP, GTP, and their generator to approximately 2% of the intact exponentially growing cells. In contrast to amino acid incorporation by intact cells, this system is sensitive to EDTA or low Mg2+. On the other hand, this system, differing from the regular cell-free system, does not respond to addition of soluble protein and ribonuclease. The ghost-infected cells were able to synthesize beta-galactosidase upon addition of the inducer isopropyl thiogalactoside. The initial rate of the induction was 2.6% of intact cells. For this induction, the addition of cyclic AMP, amino acids, ATP, GTP, UTP, CTP, and their generator was necessary. The induction of beta-galactosidase in these ghost-infected cells was very sensitive to the addition of EDTA, CaCl2, sulfhydryl blocking reagent, rifampin and chloramphenicol but insensitive to DNA synthesis inhibitors such as nalidixic acid and DNase.
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PMID:Protein synthesis in bacteriophage ghost-infected cells. 17 55

Transcription was determined in liver chromatin from rats fed for 6 days, an optimal (20%) or suboptimal (3%) amount of high-quality protein. Transcription by Escherichia coli RNA polymerase (EC 2.7.7.6) was lower after prolonged incubation with chromatin from rats fed 3% as compared with 20% protein. Differences were detected in the transcripts of the two types of chromatin after analysis by sucrose density gradient centrifugation. But no measurable differences were found in the melting profiles at low ionic strength of the two chromatin preparations. Transcription per milligram chromatin DNA was 25-fold higher using E. coli RNA polymerase instead of rat liver RNA polymerase II. The use of UTP as radioactive precursor in the absence of ATP, GTP and CTP resulted in a low labelling of RNA. One [lambda32P]UTP nucleotide was incorporated/8 UMP nucleotides. The product obtained was sensitive to ribonuclease treatment. In the presence of ATP, GTP and CTP [lambda-32P]UTP nucleotide incorporation was reduced and that of UMP nucleotide was increased giving a ratio of 1:188.
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PMID:Transcription of rat liver chromatin by Escherichia coli RNA polymerase: template properties after protein restriction. 36 67

The tRNA nucleotidyltransferase activity (3H-CMP incorporation into 3'-terminus of tRNApC) in cytoplasmic fractions of various types of cells such as Ehrlich ascites tumor cells, mouse liver and spleen cells, rat spleen, lymph node, and macrophages cells was found to be dependent on the concentrations of nucleoside 5'-triphosphates (ATP, GTP, UTP, dATP, dGTP, dCTP, and/or dTTP). The purified tRNA nucleotidyltransferase did not show such dependency. The dependency of the enzyme activity on nucleoside 5'triphosphates in the crude cytoplasmic fractions was possibly due to the presence of inhibitors which interfere with the repair system of defective 3'-termini of tRNA. Two kinds of inhibitors were distinguishable in the cytoplasmic fractions. One was unstable on heat treatment at 55 decrees C and showed ribonuclease activity for the tRNA 3'-terminus. The other which lacked ribonuclease activity was rather stable to the heat treatment and inhibited purified tRNA nucleotidyltransferase. The actions of both inhibitors were suppressed by nucleoside 5'-triphosphates.
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PMID:Effect of nucleoside 5'-triphosphates on tRNA nucleotidyltransferase activity in cytoplasmic fractions of various types of mammalian cells. 42 63

Liver mitochondrial preparations from normal, thyroidectomized, and triiodothyronine-treated thyroidectomized rats were assayed for in vitro RNA synthetic activity. Thyroidectomized rat mitochondrial preparations incorporated UTP into RNA at 70% the rate of normal control preparations. Mitochondrial preparations from triiodothyronine-treated thyroidectomized rats incorporated UTP at rates 35%-45% greater than those of sham-injected thyroidectomized rats. These differences were statistically significant and could not be attributed to inequalities in mitochondrial sampling, dilution of labeled precursor specific activity, nucleotide substrate concentrations, or differences in ribonuclease activities.
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PMID:The effect of thyroid hormone on in vitro rat liver mitochondrial RNA synthesis. 83 May 46

Nuclei from seminal vesicle epithelium of adult guinea pigs were isolated in hypertonic sucrose solution. The incorporation of [3H]UTP by the isolated nuclei into acid-precipitable products was studied. Incorporation required ATP, GTP, CTP, UTP, and Mg+2. It was inhibited by addition of actinomycin D, deoxyribonuclease, or pyrophosphate to the reaction mixture. Thus, incorporation of [3H]UTP by isolated nuclei had the same characteristics that have been demonstrated for the reactions catalyzed by nuclear RNA polymerases. Using alpha-amanitin as a metabolic tool, we established concentrations of (NH4)2SO4. Mg+2, and nucleotides that give maximum assayable activities of nuclear RNA polymerases I and II. When the activities of polymerases I and II were measured in isolated seminal vesicle nuclei of guinea pigs that had been castrated 4 days earlier, a marked decrease in activities was found relative to control values (nuclei from intact animals). No further decrease was found 8 days after castration. Diminished accessibility to the nuclear DNA template and a decrease in the concentration of RNA polymerase molecules seemed to be responsible for the observed effects of castration on activities of RNA polymerases. An increase in ribonuclease activity did not seem to be responsible for the effects of castration. Activities of the enzymes did not change 2, 3, or 4 hours after intraperitoneal injection (2 mg/kg body weight) of each of five different androgens. Similarly, a single intraperitoneal injection of testosterone did not restore enzyme activity of polymerade I or II at any time during the first 24-hour period after hormone administration.
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PMID:RNA polymerase activities in isolated nuclei of guinea pig seminal vesicle epithelium: influence of castration and androgen administration. 90 9

The synthesis of poly(A)-containing RNA by isolated mitochondria from Ehrlich ascites cells was studied. Isolated mitochondria incorporate [3H]AMP or [3H]UTP into an RNA species that adsorbs on oligo (dT)-cellulose columns or Millipore filters. Hydrolysis of the poly(A)-containing RNA with pancreatic and T1 ribonucleases released a poly(A) sequence that had an electrophoretic mobility slightly faster than 4SE. In comparison, ascites-cell cytosolic poly(A)-containing RNA had a poly(A) tail that had an electrophoretic mobility of about 7SE. Sensitivity of the incorporation of [3H]AMP into poly(A)-containing RNA to ethidium bromide and to atractyloside and lack of sensitivity to immobilized ribonuclease added to the mitochondria after incubation indicated that the site of incorporation was mitochondrial. The poly(A)-containing RNA sedimented with a peak of about 18S, with much material of higher s value. After denaturation at 70 degrees C for 5 min the poly(A)-containing RNA separated into two components of 12S and 16S on a 5-20% (w/v) sucrose density gradient at 4 degrees C, or at 4 degrees and 25 degrees C in the presence of formaldehyde. Poly(A)-containing RNA synthesized in the presence of ethidium bromide sedimented at 5-10S in a 15-33% (w/v) sucrose density gradient at 24 degrees C. The poly(A) tail of this RNA was smaller than that synthesized in the absence of ethidium bromide. The size of the poly(A)-containing RNA (approx. 1300 nucleotides) is about the length necessary for that of mRNA species for the products of mitochondrial protein synthesis observed by ourselves and others.
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PMID:The synthesis of polyadenylic acid-containing ribonucleic acid by isolated mitochondria from Ehrlich ascites cells. 98 39

Approximately one-third of the total ATP-hydrolysis activity in isolated HeLa nuclei is sensitive to RNAase (ribonuclease). This activity is selectively extracted with pulse-labelled RNA. In the extracts it co-sediments with various particles with sedimentation coefficients from 10S to 50S, but especially with 24S and 40S particles. ATP hydrolysis by the isolated particles was inhibited extensively (greater than 80%) by RNAase A, heparin and 0.2 M-NaCl. The activity of RNAase-treated particles was recovered when poly(A) was added, but not when DNA was added. The isolated particles exhibited RNAase-sensitive hydrolysis activities for dATP, GTP, CTP and UTP as well as for ATP, and the UTPase activity in the extracts showed nearly the same sedimentation distribution as the ATPase activity. When samples of isolated particles were irradiated with u.v. light in the presence of [alpha-32P]ATP, a 39 kDa polypeptide with a broad distribution from 10S to 50S like that of the ATPase and a 55 kDa polypeptide with a sharp distribution at 24S were photolabelled. Taken together, the data suggest that ATP-hydrolysis activity found in nuclear ribonucleoprotein subfractions appears to be the result of one or two RNA-dependent NTPases that are normally associated with endogenous RNA in a wide variety of particles.
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PMID:Characterization of a ribonuclease-sensitive nucleoside triphosphatase activity from HeLa nuclei. 240 2

A cytosolic factor that stimulates transcription in isolated nuclei was purified approximately 4000-fold to near homogeneity from rat liver. The molecular weight of the factor was determined as 47 000 by SDS-polyacrylamide gel electrophoresis. The factor had no detectable deoxyribonuclease and protease activity but showed ribonuclease inhibitor activity. The factor could stimulate transcription in isolated nuclei by 50% at about 3.0 ng and the maximal stimulation was about 100%. When [gamma-S]ATP and [gamma-S]GTP were included in the reaction, the factor stimulated the synthesis of RNA which was able to bind to a mercury-Sepharose column and about 80% of the bound RNA was sensitive to a low concentration of alpha-amanitin. When heparin was added before initiation to preincubation mixture containing RNA polymerases II and DNA, a small but definite incorporation of [14C]UTP was observed. The factor alone had no stimulatory effect on the heparin-resistant incorporation of [14C]UTP but, in the presence of two rat liver nuclear fractions, phosphocellulose 0.5 and 1 M KCl step fractions, could stimulate the incorporation above the level with the combination of the two nuclear fractions. Antibody raised against the factor inhibited accurate transcription from the adenovirus 2 major late promoter in a nuclear lysate from Ehrlich ascites tumor cells, and the inhibition was neutralized by the factor.
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PMID:Purification of a cytosolic factor from rat liver that stimulates transcription in isolated nuclei and its action on purified RNA polymerase II-DNA system. 407 43


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