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

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Query: EC:1.11.1.6 (catalase)
55,569 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of copper sulfate (CuSO4) on both hepatic oxidative stress and heme oxygenase induction was studied. A strong increase in in vivo rat liver chemiluminescence was observed 1 h after Cu(II) administration. To evaluate liver antioxidant enzymatic defenses, superoxide dismutase, catalase, and glutathione peroxidase activities were determined. Catalase and glutathione peroxidase were found to be significantly decreased 5 h after CuSO4 injection. In contrast, superoxide dismutase activity was increased. Heme oxygenase activity appeared 5 h after treatment, reaching a maximum value 18 h after CuSO4 administration. This induction was preceded by a decrease in the intrahepatic GSH pool and an increase in the generation of thiobarbituric acid reactive substances, both effects taking place a number of hours before induction of heme oxygenase. Administration of bilirubin, the end product of heme catabolism in mammals, and alpha-tocopherol, a widely employed antioxidant, completely prevented heme oxygenase induction as well as the decrease in hepatic GSH and the increase in chemiluminescence when administered 2 h before CuSO4 treatment. Under the same experimental conditions, beta-carotene showed a moderate preventive effect on both heme oxygenase induction and oxidative stress parameters. These data obtained with Cu(II) treatment are in agreement with our previous reports suggesting a correlation between heme oxygenase induction and oxidative stress.
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PMID:Relationship between oxidative stress and heme oxygenase induction by copper sulfate. 901 30

Heme oxygenase catalyzes the oxidation of heme to biliverdin and carbon monoxide. The gene encoding the truncated soluble rat heme oxygenase-1 (Metl-Pro267) was cloned. The enzyme protein was expressed in E. coli JM109 and purified to homogeneity. The molecular weight of the recombinant enzyme was 30 kDa as assessed by SDS-polyacrylamide gel electrophoresis. From a 3-L culture, about 90 mg of the purified enzyme was routinely obtained. The dependency of the heme oxygenase reaction catalyzed by the soluble enzyme on the NADPH-cytochrome P-450 reductase concentrations and the effect of catalase on the reaction were examined to compare with the purified membrane-bound form of heme oxygenase-1 (Yoshida and Kikuchi, 1978b). The activity of the soluble enzyme was inhibited at high concentrations of NADPH-cytochrome P-450 reductase and the inhibition was not alleviated by addition of catalase unlike the membrane-bound form. The ferric iron of the heme-heme oxygenase complex was in a typical high spin state at acidic to neutral pH (pH 6.5-7.0) but conversion to low spin state was observed at basic pH (pH 9-10). The heme bound to heme oxygenase was converted to biliverdin at a stoichiometric ratio of unity in the presence of NADPH-cytochrome P-450 reductase system. During the heme degradation of the heme-heme oxygenase complex under atmospheric oxygen, several intermediates, that is, oxygenated heme and verdoheme, were spectrally discriminated.
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PMID:Cloning and expression of cDNA for soluble form of rat heme oxygenase-1. 902 1

Heme oxygenase-2 (HO-2) is constitutively expressed in mammalian tissues; together with HO-1 (HSP32) it catalyzes the cleavage of heme to produce biliverdin IX alpha, CO and Fe. Detection of a consensus sequence of the glucocorticoid response element (GRE) in the promoter region of the HO-2 gene prompted the present study which has investigated the role of glucocorticoids (Gcs) in the regulation of HO-2 protein and transcript development in the newborn rat brain and has examined the promoter activity of the GRE in HeLa cells. Using in situ hybridization histochemistry, we noted a pronounced increase in signal for HO-2 mRNA in the brain of 14-day-old rats postnatally treated with corticosterone (5 microg/g, 4 x, starting 24-36 h after birth). And, using immunohistochemistry, a striking increase in neuronal HO-2 immunostaining in treated brains was detected. The HO-2 GRE was tested for responsiveness to dexamethasone (DX) using both a promoterless CAT expression vector, and a heterologous promoter containing luciferase expression vector in HeLa cells. The HO-2 promoter containing the GRE and transcription start site induced CAT reporter gene activity in response to DX, whereas mutation or deletion in the GRE abolished hormone responsiveness. Similarly, constructs containing the GRE conferred responsiveness to DX in an orientation-independent manner and increased relative luciferase activity. Further, specific binding of glucocorticoid receptor protein to the GRE was observed; binding could be competed out only by excess cold GRE and not by mutated HO-2 GRE, or AP1. HO-2 mRNAs (approximately 1.3 and approximately 1.9 kb) increased in HeLa cells treated with DX (5 microM), the level reached a maximum at 24 h. DX did not effect HO-1 mRNA level. The increase in the HO-2 transcript was accompanied by an increase in HO-2 protein, as assessed by Western blot analysis, and an increase in HO activity, as measured by bilirubin formation. Also, an increase in intensity of immunostaining was noted in DX-treated HeLa cells. We conclude that the GRE present in the HO-2 gene promoter region is functional, and propose the direct involvement of the adrenal glucocorticoids in modulation of HO-2 gene expression. In the context of biological functions of heme degradation products, we suggest that this regulation may be of significance, particularly to the neurons.
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PMID:Regulation of heme oxygenase-2 by glucocorticoids in neonatal rat brain: characterization of a functional glucocorticoid response element. 911 47

Perfusate levels of nitric oxide (NO)-containing compounds and guanosine 3',5'-cyclic monophosphate (cGMP) are increased in hypoxia-induced hypertensive rat lungs. To test if increased cGMP was due to NO stimulation of soluble guanylate cyclase (sGC), we examined effects of inhibition of NO synthase with N omega-nitro-L-arginine (L-NNA) on perfusate accumulation of cGMP in physiological salt solution (PSS)-perfused hypertensive lungs isolated from rats exposed for 3-4 wk to hypobaric hypoxia. Because 200 microM L-NNA did not reduce cGMP, we next examined inhibitors of other pathways of stimulation of either sGC or particulate GC (pGC). Neither 5 microM Zn-protophorphyrin, an inhibitor of CO production by heme oxygenase, nor 10 mM aminotriazole, an inhibitor of H2O2 metabolism by catalase, reduced perfusate cGMP. However, an antiserum to atrial natriuretic peptide (ANP; 100 microliters antiserum/30 ml PSS), to inhibit ANP activation of pGC, completely prevented accumulation of the nucleotide. ANP antiserum was also more effective than L-NNA in reducing lung tissue cGMP. In contrast, L-NNA but not ANP antiserum increased resting vascular tone. These results suggested that whereas ANP determined perfusate and tissue levels of cGMP, NO regulated vascular tone. To test if perfusate cGMP reflected ANP stimulation of pGC in endothelial rather than smooth muscle cells, we examined effects of 10 microM Zaprinast, an inhibitor of cGMP hydrolysis in smooth muscle but not endothelial cells, and found no increase of cGMP in hypertensive lungs. ANP levels were not elevated in hypertensive lungs, and it is unclear by what mechanism the ANP-stimulated activity of pGC is increased in hypertensive pulmonary vascular endothelial cells.
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PMID:Atrial natriuretic peptide accounts for increased cGMP in hypoxia-induced hypertensive rat lungs. 922 14

Heme oxygenase (HO) proteins are members of the HSP30 family and consist of 2 isozymes identified to date, termed HO-1 and HO-2. Separate genes encode the isozymes and protein products which are immunochemically distinct, share less than 50% similarity at the amino acid sequence level. Each form, however, shows greater than 90% similarity among species, including human and the rat (reviewed in ref.). Furthermore, these isozymes function in a well-defined role to carry out oxidation of the heme molecule (Fe-protoporphyrin IX) in concert with NADPH-cytochrome P450 reductase. The oxidation of heme is isomer specific and results in the formation of bile pigments, carbon monoxide, and iron. The heme molecule constitutes the prosthetic moiety of hemoproteins, such as hemoglobin, myoglobin, catalase, soluble guanylate cyclase, cytochrome b5, cytochromes P450 and NO synthase. HO-1 also known as heat shock protein (HSP) 32 is encoded by a gene which is exquisitely stress-responsive and a host of stimuli that mediate oxidative stress cause induction of the protein both in vivo and in vitro. The HO-2 form shows a unique pattern of regulation from that of HO-1. HO-2 is a constitutive protein and its expression is not affected by the inducers of HO-1 tested to date; rather, the only known regulator of HO-2 yet identified is adrenal glucocorticoids. The two isozymes display vast differences in tissue distribution and under normal conditions HO-1 is present in the whole brain at the limit of immunodetection and is discreetly localized in select neuronal populations. HO-1 protein (approximately 32 kDa) and its approximately 1.8 kb transcript are increased, however, in response to stressful stimuli primarily in non-neuronal cell populations. The heme oxygenase system serves in both a catabolic and anabolic capacity in the cell. In the former capacity, it down-regulates cellular heme and hemoprotein levels. And, as such it inactivates the most effective catalyst for formation of free radicals, the heme molecule. In its anabolic role, as noted above, heme oxygenase produces bile pigments, carbon monoxide, and iron, all of which are biologically active: bile pigments function as antioxidants; the carbon monoxide generated by HO activity has been correlated with the generation of cGMP; and iron regulates expression of various genes, including that of HO-1 itself, as well as transferrin receptors, ferritin, and NO synthase. We used rabbit anti-rat HO-2 polyclonal antibody and HO-2 cDNA to localize HO-2 immunoreactive protein and the 1.3- and 1.9 kb homologous transcripts, respectively, in rodent brain as visualized by histochemical staining procedures. These protocols provide the first detailed description of methodologies successfully used to define the pattern of HO-2 expression at the transcriptional and translational levels in the adult rat brain and glucocorticoid-treated newborn rats. The procedures described herein have the virtue of being non-radioactive, as well as applicability to the systemic organs, such as the cardiovascular system and the male reproductive organs. Visualization of cellular HO-2 expression aids in assessment of potential sites of carbon monoxide, iron, and bilirubin production within the nervous system.
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PMID:Histochemical localization of heme oxygenase-2 protein and mRNA expression in rat brain. 938 81

U937 cell growth in the presence of either chloramphenicol or ethidium bromide rapidly leads to respiratory deficiency. The novel finding of this report is that this response is paralleled by a specific increase in Se-dependent and independent glutathione peroxidase activities as well as of glutathione peroxidase and heme oxygenase mRNAs. Under the same experimental conditions, catalase activity and catalase mRNA do not show appreciable changes. These results can be explained by an increased formation of H2O2 at the early times of development of respiratory deficiency followed by induction of antioxidant enzymes.
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PMID:Mitochondrial respiratory chain deficiency leads to overexpression of antioxidant enzymes. 942 22

Using chick heme oxygenase-1 (cHO-1) cDNA as a probe, three independent clones were identified from screening a lambda FixII chick genomic library. Genomic Southern blots using this cDNA probe or a cHO-1 5' specific probe showed that cHO-1 is a single-copy gene. Based on restriction enzyme analysis, Southern blots, polymerase chain reaction analysis and DNA sequencing, it was confirmed that the three overlapping clones isolated cover the entire cHO-1 gene, as well as approximately 10 kb of the flanking regions on both ends. As with mammalian HO-1x, cHO-1 has five exons and four introns. Computer analysis of the DNA sequence obtained identified consensus sequences corresponding to numerous transcription factor recognition elements. These include AP-1, AP-2, NF-kB, C/EBP, c-Myc and a metal-responding element identified in the promoter region, and two Sp-1 elements in intron 1. Transient expression studies in transfected primary cultures of chick embryo liver cells showed that a CAT reporter gene construct containing 2.8 kb of the cHO-1 promoter region responded to sodium arsenite, H2O2, transition metals and 12-0-tetradecanoylphorbol 13-acetate, but not to heme. Studies with deletion mutants, consisting of various lengths of the cHO-1 promoter region, indicated that there are two regions important for sodium arsenite induction, one located between residues -1642 and -1293, and the second located in the first 263 base pairs of the cHO-1 promoter. DNA binding studies by electrophoretic mobility shift assay showed that nuclear protein isolated from primary cultures of chick embryo liver cells bound to the oligonucleotide probe containing an AP-1 element identified at -1573 to -1580. In addition, such binding was increased by cobalt or sodium arsenite treatment.
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PMID:Molecular cloning, characterization, and expression of the chicken heme oxygenase-1 gene in transfected primary cultures of chick embryo liver cells. 951 60

Heme oxygenase is a key enzyme for heme catabolism and catalyzes the oxidative degradation of heme to form biliverdin IX alpha, an immediate precursor of bilirubin. In order to shed light on the mechanism by which UVA radiation causes oxidative damage, the relationship between heme oxygenase induction and oxidative stress was studied. HO-1 activity, lipid peroxidation and generation of active oxygen species (H2O2) were measured in rat liver exposed to UVA radiation. Besides, soluble and enzymatic antioxidant defenses (GSH, SOD, CAT and GSH-Px) were determined, while bilirubin antioxidant capacity was also evaluated. UVA radiation markedly increased both lipid peroxidation (180% +/- 7; S.E.M., n = 9 over control value of 0.1 +/- 0.01 nmol MDA/min per mg prot.) and steady state concentration of hydrogen peroxide (4 +/- 0.03 microM; S.E.M., n = 9) 3 h after treatment. At the same time, GSH content decreased to 3.6 +/- 0.2 mumol/g liver (S.E.M., n = 9) increasing thereafter. Antioxidant enzymes reached minimum values 6 h after UVA treatment (SOD: 7.2 +/- 0.2 U/mg protein, CAT: 7.8 +/- 0.2 pmol/mg protein, GSH-Px: 0.088 +/- 0.004 U/mg protein; S.E.M., n = 9), starting to increase 12 h after irradiation. HO-1 induction was observed 6 h after UVA irradiation, reaching a maximum value of 2.5 +/- 0.03 U/mg protein (S.E.M., n = 9) 12 h after treatment, and then declined until it reached control levels 24 h after exposure. Administration of bilirubin 2 h before UVA irradiation, entirely prevented HO-1 induction, the increase in MDA content and the decrease in GSH levels. This study shows that UVA irradiation leads to oxidative stress as evidenced by increased MDA content and H2O2 steady state levels, and depletion of GSH, SOD, CAT and GSH-Px. All these changes produced HO-1 induction. It is concluded that the induction of this enzyme could be a response to oxidative stress, since bilirubin can act as a physiological antioxidant.
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PMID:Heme oxygenase induction by UVA radiation. A response to oxidative stress in rat liver. 960 82

Intracellular metabolism of chromium(VI) [Cr(VI)] may lead to oxidative stress and this may account for the ability of Cr(VI) to act as a complete carcinogen. Therefore, we examined the effects of Cr(VI) treatment on the expression of oxidative stress genes in normal human lung LL 24 cells and human lung adenocarcinoma A549 cells. RT-PCR and northern blot analyses were used to determine the steady-state mRNA levels of catalase, glutathione S-transferase, glutathione reductase, Cu/Zn- and Mn-superoxide dismutases, glutathione peroxidase, NAD(P)H:quinone oxidoreductase, heme oxygenase and interleukin 8 in control cells and cells treated with 5-200 microM of Cr(VI). We found that only expression of the heme oxygenase gene is strongly elevated under the treatment with Cr(VI), and only in normal human lung LL 24 cells. Our data showed that even in the absence of Cr(VI) treatment, the level of heme oxygenase gene expression is much higher in A549 cells than in LL 24 cells. As glutathione is believed to play a protective role in cells against different forms of oxidative stress, we studied the correlation between intracellular glutathione levels and the inducibility of the heme oxygenase gene after treatment of cells with Cr(VI). Our results demonstrate that glutathione levels are increased by 35 % of control values in LL 24 cells treated with Cr(VI). The data obtained indicate that heme oxygenase, known to be a stress-inducible gene, may be involved in cellular pathways critical to the carcinogenic activity of Cr(VI) in normal human lung cells. Intracellular glutathione levels and reactive oxygen species do not appear to be primarily responsible for the stress response, induced by Cr(VI) in the studied human cells.
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PMID:Effects of Cr(VI) on the expression of the oxidative stress genes in human lung cells. 974 36

There is currently renewed interest in the biological significance of heme proteins. The most common heme proteins include hemoglobin, myoglobin, cytochromes, and redox enzymes such as catalase and peroxidase. Setaria digitata is a cattle filarial parasite, which is devoid of typical cytochrome systems. However, studies showed activities of delta Aminolevulinate synthase (ALAS), delta Aminolevulinate dehydratase (ALAD), and heme oxygenase in appreciable amounts, suggesting the presence of necessary equipment for the biosynthesis of heme. This is further confirmed by the end product inhibition of ALAS by heme and the observation of the death of the parasite by succinyl acetone, an inhibitor of the biosynthesis of heme. Though typical cytochrome systems are absent, microsomal cytochrome P 450 and elevated levels of heme containing enzymes such as catalase and peroxidase are present in the parasite. A unique hemoglobin is also detected which shows a difference in biological functions from the host system and that of the much-studied nematode parasite Ascaris sum.
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PMID:Presence and formation of heme and occurrence of certain heme proteins in the filarial parasite Setaria digitata. 987 18


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