Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A synthetic DNA fragment encoding a protease precursor of the human immunodeficiency virus type 2 (HIV2) was cloned and expressed in bacteria and yeast. A recombinant plasmid encoding a hybrid polypeptide consisting of human superoxide dismutase and an HIV2 protease precursor of 113 amino acids was constructed for regulated intracellular expression in bacteria. Induction of this plasmid produced an autoprocessed form of the retroviral enzyme possessing the correct molecular weight. Overexpression and secretion of the protease from yeast was achieved with an expression vector encoding the yeast pheromone alpha-factor signal/leader sequence fused to a protease precursor of 115 amino acids. Amino-terminal sequence analysis confirmed that the viral enzyme exported from yeast was correctly processed from its precursor by cleavage of the predicted Ala-Pro peptide bond located at the NH2 terminus of the protease in the pol open reading frame. No additional amino acid residues were required at the COOH terminus of the protease for this autoproteolytic event. The HIV2 protease expressed in bacteria and yeast was active in an in vitro assay when tested on the HIV1 polyprotein precursor, myristylated Pr53gag. Two synthetic peptides representing junction sequences in the HIV1 gag-pol precursor were used to assay purified HIV2 protease. The enzyme exhibited a kcat/KM of 23.2 min-1 mM-1 on the HIV1 matrix-capsid junction peptide and a kcat/KM of 71.4 min-1 mM-1 on the protease-reverse transcriptase junction peptide. These rates show that the HIV2 enzyme is efficient at hydrolyzing the HIV1 peptide junctions, revealing the analogous nature of the substrate specificities of the two enzymes.
 ...
PMID:Recombinant HIV2 protease processes HIV1 Pr53gag and analogous junction peptides in vitro. 219 46

The phylogenetic status of members of the genus Lactococcus and some motile strains which react with Lancefield group N antiserum was examined by reverse transcriptase sequencing of 16S ribosomal ribonucleic acid. In agreement with earlier nucleic acid hybridization and immunological studies of superoxide dismutase the 16S sequence data clearly demonstrate that the lactococci represent a distinct phylogenetic group equivalent in rank to the genera Enterococcus and Streptococcus. The motile group N strains from chicken faeces and river water, however, were found to be phylogenetically unrelated to lactococci but displayed a closer, albeit loose, association with members of the genus Enterococcus. On the basis of the present sequence data and earlier chemotaxonomic studies it is proposed that the motile group N strains be classified in a new genus Vagococcus, as Vagococcus fluvialis sp. nov. The type strain of V. fluvialis is NCDO 2497.
 ...
PMID:16S ribosomal ribonucleic acid sequence analyses of lactococci and related taxa. Description of Vagococcus fluvialis gen. nov., sp. nov. 247 30

Manganese-containing superoxide dismutase (MnSOD-sodA) in Escherichia coli (E. coli) is regulated at the transcriptional level as observed in studies using both operon and gene fusions. In this paper we examine the regulation of sodA gene at the level of mRNA. We examine the effects of several aerobic inducing conditions (i.e., nalidixic acid, paraquat, or 2,2'-dipyridyl) on mRNA stability, transcription initiation, and translation. The half-life of sodA mRNA was found to be approximately 3-4 min, showing no differences in mRNA stability between induced and uninduced cells. We also found, by reverse transcriptase, that the second putative promoter is not functional under normal or stress conditions, and the amount of mRNA was found to be proportional to active MnSOD. Thus, these results indicate that under oxidative stress/inducing conditions, the increase in aerobic transcription of sodA occurs from only one transcription start site without affecting the stability of sodA mRNA. In addition, the 1:1 ratio found between increases in sodA mRNA and active MnSOD suggests that no translational regulation occurs aerobically.
 ...
PMID:Stability of Escherichia coli sodA mRNA and identification of the transcriptional start site(s) under different environmental and oxidative stresses. 798 26

The high sensitivity of reverse transcriptase-polymerase chain reaction for detecting low copy number mRNA transcripts has been standardized to analyze the mRNA profiles of catalase, glutathione peroxidase, CuZn-superoxide dismutase and aldose reductase, with respect to the housekeeping gene cyclophilin, in rat lenses cultured in hyperglycemic (50mM glucose) or oxidative (100 microM H2O2) media for 24, 40 and 60 hr. In response to hyperglycemia mRNA expression of catalase appeared to be inhibited at 24 hr but attained normal levels by 40 hr. On the other hand, mRNA levels of catalase were higher than normal between 40 and 60 hr in the presence of H2O2. Glutathione peroxidase mRNA abundance although enhanced in response to both hyperglycemia as well as H2O2-induced stress, displayed opposite trends with time-an increase from 24-60 hr due to hyperglycemia and a decrease to normal by 60 hr in the presence of H2O2. In contrast, CuZn-superoxide dismutase was inhibited at 50 mM glucose achieving baseline levels by 60 hr, while H2O2 elicited an induction at 24 hr which waned to basal levels by 60 hr. Interestingly, aldose reductase was unaffected by hyperglycemia but showed an appreciable increase with time upon exposure of the lens to H2O2. The role of these enzymes in cataractogenesis with regard to their respective mRNA levels is discussed.
 ...
PMID:Semi-quantitation of mRNA by polymerase chain reaction. Levels of oxidative defense enzymes and aldose reductase in rat lenses cultured in hyperglycemic or oxidative medium. 873 24

This study investigated whether hypoxia affected the expression of mitochondrial manganese-containing superoxide dismutase (Mn-SOD) and the cytosolic copper and zinc-containing superoxide dismutase (Cu,Zn-SOD) in alveolar type II epithelial (ATII) cells and lung fibroblasts. Cells were exposed in vitro to air (controls) or to 2.5% oxygen (hypoxia) for 24 h. Mn-SOD and Cu,Zn-SOD mRNA expression was measured by quantitative reverse transcriptase-polymerase chain reaction. Both Mn-SOD and Cu,Zn-SOD mRNA expression in ATII cells decreased significantly after 1 day in hypoxic conditions. The decrease in Mn-SOD mRNA (-69%) was greater than that in Cu,Zn-SOD mRNA (-48%). ATII cell surfactant protein A transcript expression remained constant. Mn-SOD (-52%) and Cu,Zn-SOD (-54%) mRNA expression decreased similarly in lung fibroblasts cultured during hypoxia. The half-life of the Mn-SOD mRNA measured in lung fibroblasts exposed to air or hypoxia for 24 h decreased significantly from 5.8 +/- 0.1 to 3.8 +/- 0.7 h (-34%). The half-life for the Cu,Zn-SOD decreased significantly from 4.0 +/- 0.3 to 2.4 +/- 0.1 h (-40%). Neither Mn-SOD nor Cu,Zn-SOD protein expression in ATII cells changed significantly during hypoxia. Hypoxia decreases expression of Mn-SOD and Cu,Zn-SOD mRNA in ATII cells and lung fibroblasts in part by decreasing stability of the mRNA transcripts.
 ...
PMID:Effects of hypoxia on expression of superoxide dismutases in cultured ATII cells and lung fibroblasts. 899 66

Using a reverse transcriptase polymerase chain reaction (RT-PCR), a complement DNA encoding secreted superoxide dismutase (s-SOD) of a mouse kidney has been isolated and the nucleotide sequence was determined. The deduced amino acid sequence of mouse s-SOD cDNA shares 79% identity with the rat seminal SOD sequence and 61% identity with the human SOD3 sequence. Northern blot analysis showed that mouse s-SOD is intensely expressed in the kidney and lung tissues and detectable in other tested tissues, including the brain. The mouse s-SOD gene was assigned to chromosome 5 using fluorescence in situ hybridization analysis and PCR analysis of mouse/hamster hybrid cells.
 ...
PMID:Sequence analysis, tissue expression and chromosomal localization of a mouse secreted superoxide dismutase gene. 916 33

Because programmed cell death (PCD) is an important mode of pericyte dropout in human diabetic retinopathy, whether increased oxidative stress in cells with diminished antioxidant defenses plays a causative role in the PCD process in diabetic pericytes has been studied. Ten diabetic and eight non-diabetic eye-bank eyes from 5 diabetic and 4 non-diabetic patients were included in this study. From individual neural retinas pericytes were isolated by a newly developed immunomagnetic technique. Total mRNA of the purified pericytes was isolated for quantitative reverse transcriptase (RT)-PCR assay. mRNA levels of a death protease (CPP32), the major enzyme that initiates the proteolytic cascade leading to cell death, were determined in association with the expression of antioxidative enzymes including glutathione peroxidase (GSH-Px), glutathione reductase, CuZn superoxide dismutase (SOD), MnSOD and catalase genes in pericytes. In comparison with pericytes from non-diabetic retinas, pericytes from diabetic retinas highly expressed CPP32 genes (4 +/- 0.6 fold increase, p < 0.01, n = 9). In diabetic pericytes, up-regulation of glutathione peroxidase (GSH-Px) (8.2 +/- 0.9 fold increase, p < 0.01, n = 9) and down-regulation of glutathione reductase (Gr) (4.1 +/- 0.4 fold decrease, p < 0.05, n = 9) and CuZnSOD (2.1 +/- 0.7 fold decrease, p < 0.05, n = 9) were observed. mRNA levels of MnSOD and catalase of diabetic pericytes did not differ significantly from those of non-diabetic pericytes. Overexpression of a member of interleukin-1 beta-converting enzyme (ICE) family, CPP32, indicated that the pericytes from diabetic retinas are in a "pre-PCD" state. This is the first evidence that the ICE family of death proteases is involved in pericyte dropout in diabetes. In these pre-PCD cells, the expression of antioxidant enzyme genes also was changed. Up-regulation of GSH-Px indicates a compensation mechanism to meet the demand of excessive glutathione in reduced form. Decreased levels of both glutathione reductase and CuZnSOD, despite the oxidative stress in the diabetic condition, suggest the breakdown of the antioxidant defense in pericytes. Most importantly, the altered gene profile of scavenging enzymes under diabetic conditions, correlating with overexpression of the cell death protease gene, together suggest increased oxidative stress as an etiological agent of pericyte dropout in diabetic retinopathy.
 ...
PMID:Altered mRNA levels of antioxidant enzymes in pre-apoptotic pericytes from human diabetic retinas. 1009 40

Resveratrol (3,5,4'-trihydroxy-trans-stilbene) is a naturally occurring compound shown to inhibit carcinogen-induced preneoplastic lesion formation in mouse mammary organ culture and tumorigenesis in the two-stage mouse skin model. Cancer chemopreventive potential was also suggested in various assays reflective of the three major stages of carcinogenesis. Anti-initiation activity was indicated by its antioxidant and antimutagenic effects, inhibition of the hydroperoxidase function of cyclooxygenase (COX), and induction of phase II drug-metabolizing enzymes. Antipromotion activity was indicated by antiinflammatory effects, inhibition of production of arachidonic acid metabolites catalyzed by either COX-1 or COX-2, and chemical carcinogen-induced neoplastic transformation of mouse embryo fibroblasts. Antiprogression activity was demonstrated by its ability to induce human promyelocytic leukemia (HL-60) cell differentiation. Moreover, pretreatment of mouse skin with resveratrol significantly counteracted 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced oxidative stress, as evidenced by numerous biochemical responses. Resveratrol reduced the generation of hydrogen peroxide, and normalized levels of myeloperoxidase and oxidized-glutathione reductase activities. It also restored glutathione levels and superoxide dismutase activity. As judged by the reverse transcriptase-polymerase chain reaction, resveratrol selectively inhibited TPA-induced expression of c-fos and transforming growth factor-beta 1 (TGF-beta 1), but did not affect other TPA-induced gene products including COX-1, COX-2, c-myc, c-jun, and tumor necrosis factor-alpha. These data indicate that resveratrol may interfere with reactive oxidant pathways and/or modulate the expression of c-fos and TGF-beta 1 to inhibit tumorigenesis in mouse skin. As reported herein, in addition to the activities described above, resveratrol inhibited the de novo formation of inducible nitric oxide synthase (iNOS) in mouse macrophages stimulated with lipopolysaccharide. This finding suggests an additional mechanism by which resveratrol may function as a cancer chemopreventive agent.
 ...
PMID:Cancer chemopreventive activity of resveratrol. 1037 Aug 67

Resveratrol (3,5,4'-trihydroxy-trans-stilbene) is a natural product shown to inhibit carcinogen-induced pre-neoplastic lesions in mouse mammary organ culture and 12-O-tetradecanoylphorbol-13-acetate (TPA)-promoted mouse skin tumors. Application of TPA to mouse skin induces oxidative stress, as evidenced by numerous biochemical responses, including significant generation of H2O2 and enhanced levels of myeloperoxidase and oxidized glutathione reductase activities and decreases in glutathione levels and superoxide dismutase activity. TPA treatment also elevates the expression of cyclooxygenase-1 (COX-1), cyclooxygenase-2 (COX-2), c-myc, c-fos, c-jun, transforming growth factor-beta1 (TGF-beta1) and tumor necrosis factor-alpha (TNF-alpha). As currently reported, pre-treatment of mouse skin with resveratrol negated several of these TPA-induced effects in a dose-dependent manner. H2O2 and glutathione levels were restored to control levels, as were myeloperoxidase, oxidized glutathione reductase and superoxide dismutase activities. As judged by reverse transcriptase-polymerase chain reaction (RT-PCR), TPA-induced increases in the expression of c-fos and TGF-beta1 were selectively inhibited. These data suggest that resveratrol inhibits tumorigenesis in mouse skin through interference with pathways of reactive oxidants and possibly by modulating the expression of c-fos and TGF-beta1.
 ...
PMID:Effects of resveratrol on 12-O-tetradecanoylphorbol-13-acetate-induced oxidative events and gene expression in mouse skin. 1038 Nov 33

The high event-free survival rates of Down syndrome (DS) children with acute myeloid leukemia (AML) are due, in part, to increased in vitro sensitivity of DS myeloblasts to cytosine arabinoside (ara-C) and daunorubicin and the greater generation of ara-C triphosphate (ara-CTP) from ara-C compared with myeloblasts from non-DS patients (Taub et al, Blood 87:3395, 1996). This study further explores the molecular basis of chemotherapy sensitivity of DS AML patients by examining the expression of chromosome 21-localized genes in myeloblasts from newly diagnosed AML patients. Transcript levels of two chromosome 21-localized genes, cystathionine-beta-synthase (CBS) and superoxide dismutase (SOD), measured by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), were 12.0- and 3. 8-fold higher in DS compared with non-DS myeloblasts (P <.0001 and P <.0001, respectively). Conversely, there were no significant increases in transcripts for 2 other chromosome 21-localized genes, carbonyl reductase and the reduced folate carrier. CBS transcript levels correlated with both in vitro ara-C sensitivity measured by the 3-[4,5-dimethyl-thiazol-2-yl]-2,5-diphenyltetrazolium-bro mid e (MTT) assay (P =.003) and the generation of (3)H-ara-C triphosphate (ara-CTP) after in vitro incubations with 5 micromol/L (3)H-ara-C (P =.0003). Transcripts of deoxycytidine kinase were 2.6-fold higher in DS compared with non-DS cells and may be a factor in the enhanced metabolism of ara-C in DS cells. There was no significant correlation of SOD transcripts with in vitro ara-C and daunorubicin sensitivities. Increased CBS transcripts could result in elevated CBS activity, which modulates ara-C metabolism by altering reduced folate pools, deoxycytidine triphosphate pools, S-adenosylmethionine levels, and/or methylation of the deoxycytidine kinase gene. The further identification of the molecular mechanisms of chemotherapy sensitivity of DS AML patients may lead to significant improvements in the treatment and cure of AML.
 ...
PMID:Expression of chromosome 21-localized genes in acute myeloid leukemia: differences between Down syndrome and non-Down syndrome blast cells and relationship to in vitro sensitivity to cytosine arabinoside and daunorubicin. 1043 27


1 2 3 4 5 6 7 8 Next >>