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:1.6.5.2 (NQO1)
6,196 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Induction of cellular detoxification enzymes can increase detoxification of carcinogens and reduce carcinogen-induced mutagenesis and tumorigenesis. To determine if the dietary anticarcinogen ellagic acid induced enzymes which detoxify xenobiotics and carcinogens, we examined the effect of ellagic acid on the expression of the phase II detoxification enzyme NAD(P)H:quinone reductase (QR). QR is induced by xenobiotics and antioxidants interacting with the xenobiotic responsive and antioxidant responsive elements of the 5' regulatory region of the QR gene. Ellagic acid is structurally related to the antioxidants which induce QR and we proposed that ellagic acid would induce QR expression through activation of the antioxidant responsive element of the QR gene. Rats fed ellagic acid demonstrated a 9-fold increase in hepatic and a 2-fold increase in pulmonary QR activity, associated with an 8-fold increase in hepatic QR mRNA. To determine if this increase in QR mRNA was due to activation of the antioxidant responsive element, transient transfection studies were performed with plasmid constructs containing various portions of the 5' regulatory region of the rat QR gene. These transfection studies confirmed that ellagic acid induces transcription of the QR gene and demonstrated that this induction is mediated through the antioxidant responsive element of the QR gene.
...
PMID:Ellagic acid induces NAD(P)H:quinone reductase through activation of the antioxidant responsive element of the rat NAD(P)H:quinone reductase gene. 752 86

NAD(P)H:quinone oxidoreductase1 (DT-diaphorase or NQO1) is a flavoprotein that promotes obligatory two-electron reduction of quinones, preventing their participation in redox cycling, oxidative stress, and neoplasia. NQO1 is ubiquitously expressed. However, a large amount of variation in NQO1 gene expression was noticed among various human tissues. NQO1 gene is upregulated in livers of hepatocarcinoma patients, and its expression is induced in response to a variety of compounds, including planar aromatic hydrocarbons, phenolic antioxidants/chemoprotectors, tumor promoters, and hydrogen peroxide. Deletion mutagenesis in the NQO1 gene promoter identified several cis-elements including antioxidant response element (ARE), xenobiotic response element, and AP2 element, which regulate the expression and induction of the NQO1 gene. Among these DNA elements, ARE is the most important cis-element required for high basal expression of the NQO1 gene in tumor tissues, as compared to the normal tissues of the same origin, and for its induction in response to xenobiotics and antioxidants. Nucleotide sequence analysis of the ARE indicated presence of three AP1/AP1-like elements and a GCA box. Mutational analysis indicated a requirement of two AP1/AP1-like elements arranged as inverse repeats at the interval of three base pairs for the ARE activity. The GCA box in the ARE was required for optimum basal and induced expression. ARE is a novel cis-element because a single AP1/AP1-like element did not stimulate gene expression in response to xenobiotics and antioxidants. Band shift and supershift assays identified Jun, Fos, and novel proteins in the hARE-nuclear protein complexes that mediate regulation of the NQO1 gene expression.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:NAD(P)H:quinone oxidoreductase1 (DT-diaphorase): expression, regulation, and role in cancer. 762 Feb 21

Mammalian organisms possess a variety of enzymes that catalyze the biotransformation of numerous chemicals with diverse structure. The gene superfamily comprising the cytochrome P-450 monooxygenases (P-450) are key participants in these reactions, and certain P-450 genes are highly inducible upon xenobiotic exposure. Many of the standard techniques used in the study of these systems rely on the disruption of tissues and cells, together with the preparation of subcellular particles. We have adopted a sensitive new technique, scanning laser cytometry, to monitor P-450-mediated O-dealkylation activities directly in cultured cells. Metabolism in single cells was quantified by fluorescence detection of resorufin, the P-450-mediated O-dealkylation product of alkoxyresorufin ether substrate probes. Functional activities associated with P-4501A1 and NADPH DT-diaphorase were compared among a human hepatoma (Hep G2) cell line and cells derived from mouse (Hepa 1clc7 wt) and rat (H4-II-E) hepatomas. Pretreating cells with the polyaromatic hydrocarbon inducer beta-naphthoflavone resulted in 50- to 100-fold increases in single cell rates of O-dealkylation of ethoxyresorufin (EROD activity). The use of scanning laser cytometry enabled in situ analysis of both constitutive and inducible biotransformation activities without disruption of cells or intracellular processes that determine the toxicologic fate of exogenous chemicals in vivo.
...
PMID:Direct determination of functional activity of cytochrome P-4501A1 and NADPH DT-diaphorase in hepatoma cell lines using noninvasive scanning laser cytometry. 769 59

Antioxidant response elements (AREs) containing 12-O-tetradecanoylphorbol-13-acetate response element (TRE) (perfect AP1) and TRE-like (imperfect AP1) elements mediate high basal transcription of the NAD(P)H:quinone oxidoreductase1 (NQO1) and glutathione S-transferase Ya genes in tumor cells and its induction in response to xenobiotics and antioxidants. Mutations in the human NQO1 gene ARE (hARE) revealed the requirement for two TRE or TRE-like elements arranged in inverse orientation at the interval of three base pairs and a GC box for optimal expression and beta-naphthoflavone induction of the NQO1 gene. A single TRE element from the human collagenase gene failed to respond to beta-naphthoflavone. These results demonstrate that ARE (2 x TRE or TRE-like elements)-containing detoxifying enzyme genes and not genes that contain 1 x TRE are responsive to xenobiotics and antioxidants. Bandshift assays showed shifting of a complex of more or less similar mobility with hARE and TRE that could be competed by each other. Mutations in the 3'-TRE of the NQO1 gene hARE eliminated binding of nuclear proteins to the hARE and resulted in the loss of basal and induced expression, indicating that 3'-TRE is the most important element within the hARE. 5'-TRE-like element within the NQO1 gene hARE is required for xenobiotic response but may not bind to the nuclear proteins by itself. The GC box located immediately following the 3'-TRE is required for optimal expression and induction of the NQO1 gene. The comparison of AREs from several different genes indicated the requirement for specific arrangement and spacing of two TRE and TRE-like elements within the AREs.
...
PMID:ARE- and TRE-mediated regulation of gene expression. Response to xenobiotics and antioxidants. 789 38

The effect of sera from smoking and non-smoking women in the first trimester of pregnancy (8-11 weeks gestation) was tested on the activation of Phase I enzymes, aryl hydrocarbon hydroxylase and oestrogen hydroxylase, and Phase II enzymes, quinone reductase and catechol O-methyl transferase in explants prepared from first trimester placentae of smoking and non-smoking women. Addition of 10% sera for 16 h to explants from both smoking and non-smoking women significantly affected the activity of these enzymes although the effect varied according to the enzyme studied. Differences were also found in the response of smokers compared to controls. The 2% maternal serum or 10% male serum used as control had no effect on any enzyme activity. In conclusion, gestation age-matched maternal sera exert a significant effect upon the activity of placental xenobiotic metabolic enzymes in vitro early in pregnancy, supporting the view that the maternal environment may have a role in controlling placental metabolism which is altered by cigarette smoking.
...
PMID:Modulatory effect of maternal serum on xenobiotic metabolizing activity of placental explants: modification by cigarette smoking. 796 69

The effects of Metanil yellow, Orange II and their blend on hepatic xenobiotic metabolizing enzymes were compared. Parenteral administration of Metanil yellow and Orange II to rats at a dose of 80 mg/kg body weight for 3 days caused a significant induction of ethoxyresorufin-O-deethylase (40-190%), aniline hydroxylase (27-92%), aryl hydrocarbon hydroxylase (50-62%) and aminopyrine N-demethylase (42-49%) activities. Metanil yellow and Orange II brought about a substantial increase in cytosolic quinone reductase (34-82%) and glutathione S-transferase (23-43%) activities and significant depletion of glutathione levels with a concomitant increase in lipid peroxide formation. A blend (1:1) of Metanil yellow and Orange II showed a synergistic or additive effect on these hepatic parameters, suggesting that the addition of these two prohibited dyes together in foodstuffs may give rise to more toxic effects than are produced by each dye individually.
...
PMID:Effect of metanil yellow, orange II and their blend on hepatic xenobiotic metabolizing enzymes in rats. 804 63

Human NAD(P)H:quinone oxidoreductase2 (NQO2) gene, 1336 base pairs (bp) of the 5'-flanking region and 165 bp of the 3'-flanking region, have been sequenced. NQO2 gene is 20 kilobase pairs in length and have seven exons interrupted by six introns as compared to the previously cloned NQO1 gene which contains six exons. 187 bp of the first exon in the NQO2 gene are noncoding and are absent in the NQO1 gene. 92 bp of the second exon in the NQO2 gene corresponded to the first exon of the NQO1 gene and so on. The sizes and nucleotide sequences of exons 3-6 are highly conserved between NQO2 and NQO1 genes. The last exon in the NQO2 gene is 1603 bp shorter than the last exon of the NQO1 gene and encodes for 58 amino acids as compared to 101 amino acids encoded by the NQO1 gene. This makes NQO2 protein 43 amino acids shorter than the NQO1 protein. The high degree of conservation between NQO2 and NQO1 gene organization and sequence confirmed that NQO2 gene encodes for a second member of the NQO gene family in human. Nucleotide sequence analysis of the 5'-flanking region of the NQO2 gene revealed presence of four SP1 binding sites at positions -214, -170, -106, and -75, a single copy of the antioxidant response element (ARE) at nucleotide -936, and three copies of xenobiotic response element (XRE) at positions -708, -557, and -51. ARE and XRE elements have previously been found in the promoters of the NQO1 and glutathione S-transferase Ya subunit genes and mediate increases in their expression in response to polycyclic aromatic compounds, phenolic antioxidants, and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), respectively. The NQO2 cDNA-derived protein in monkey kidney COS1 cells efficiently catalyzed nitroreduction of anti-tumor compound CB10-200, an analog of nitrophenylaziridine. Northern blot analysis indicates that NQO2 gene is expressed in human heart, brain, lung, liver, and skeletal muscle but does not express in placenta. In contrast, the NQO1 gene was expressed in all human tissues. Large variations were noticed for expression of the NQO2 and NQO1 genes among various tissues, 1336 bp of the 5'-flanking region of the NQO2 gene containing ARE and XRE was found sufficient to increase expression of the CAT gene in response to beta-naphthoflavone and tCDD in transfected human hepatoblastoma (Hep-G2) cells.
...
PMID:Human NAD(P)H:quinone oxidoreductase2. Gene structure, activity, and tissue-specific expression. 818 56

Levels of mRNAs encoding class-alpha glutathione transferases, class-mu glutathione transferases, quinone reductase, and cytochrome P450 1A were measured after xenobiotic induction in murine tissues and in the Hepa1c1c7 murine hepatoma cell line. RNA levels in liver and intestinal mucosa were determined after induction with phenobarbital, butylated hydroxyanisole, beta-naphthoflavone, isosafrole, or combinations of these compounds. The tissue culture cells were presented with combinations of butylated hydroxyanisole, tert-butyl-hydroquinone, and beta-naphthoflavone. In murine liver and intestinal mucosa, the greatest induction (5-15-fold) of glutathione transferases and quinone reductase was seen with butylated hydroxyanisole. Administration of phenobarbital or beta-naphthoflavone has only a modest effect (2-3-fold). In contrast, cytochrome P450 1A mRNA levels increase only slightly after BHA induction but are induced dramatically by beta-naphthoflavone. The pattern of induction is different in Hepa1c1c7 cells; there the greatest induction of all mRNAs occurred with beta-naphthoflavone. Administration of antioxidants with other xenobiotics increases mRNA levels only slightly over the levels obtained with BHA in murine tissues, or with beta-naphthoflavone in Hepa1c1c7 cells. mGSTM1 (GT8.7, Yb1), the most abundant glutathione transferase mRNA in murine liver, is also the most abundant glutathione transferase mRNA in both normal and induced Hepa1c1c7 cells. Our results suggest that BHA induction in murine liver and intestinal mucosa of class-mu and class-alpha glutathione transferases may involve regulatory elements and mediators that function poorly in Hepa1c1c7 cells.
...
PMID:Differences in induction by xenobiotics in murine tissues and the Hepa1c1c7 cell line of mRNAs encoding glutathione transferase, quinone reductase, and CYP1A P450s. 822 Apr 36

The glucosinolate hydrolysis product 1-isothiocyanato-3-(methylsulfinyl)-propane (IMSP), also known as iberin, is consumed in the average human (US) diet at approximately 1 mumol/kg/day. The chemoprotective effects observed with the consumption of cruciferous vegetables may be due to the presence of specific glucosinolate hydrolysis products either within the crucifers, or formed after ingestion of the crucifers. The mechanism of chemoprotection may be through selective induction of components of Phase II xenobiotic metabolizing enzymes. The influence of repeated administration of low concentrations of IMSP by gavage on components of Phase I and Phase II xenobiotic metabolizing systems was examined in the liver and small intestine of male Fischer 344 rats. Doses of 1, 10 and 100 mumol IMSP/kg, administered by gavage for 7 days, did not alter weight gain, or hepatic and renal weights, relative to body weight, and did not cause any histological lesions. Intestinal glutathione S-transferase (GST) activity and NAD(P)H:quinone reductase (QR) activities were significantly elevated to 3.1 and 8.1 times control values, respectively, at the 100 mumol/kg dose only. The administration of IMSP at 1, 10 or 100 mumol/kg had no significant effect on hepatic Phase I enzymes activities (cytochrome P-450 concentrations, ethoxycoumarin O-deethylase [ECD] and aminopyrine N-demethylase [AND] activities) or Phase II enzyme activities (GST, QR and UDP-glucuronosyltransferase [UDP-GT] activities towards 1-naphthol or 4-hydroxybiphenyl), at any of the doses tested and no effect on intestinal enzyme activities at doses below 100 mumol IMSP/kg. It is concluded that IMSP does not have a significant influence on induction of the Phase I or Phase II xenobiotic metabolizing enzymes in rats when tested at doses approximating those found in the human diet.
...
PMID:Effects of 1-isothiocyanato-3-(methylsulfinyl)-propane on xenobiotic metabolizing enzymes in rats. 822 30

Xenobiotic regulatory elements have been identified for enzymes which ameliorate oxidative damage in cells. Zeta (zeta)-crystallin, a taxon-specific enzyme/crystallin shown to be a novel NADPH-dependent quinone reductase, is found in a number of tissues and cell types. This study shows that zeta-crystallin is present in mouse lens epithelium, as well as in the alpha TN4 mouse lens epithelial cell line. To determine whether zeta-crystallin is an inducible quinone reductase, cell cultures were exposed to the xenobiotics, 1,2-naphthoquinone and beta-naphthoflavone. Assays of cellular homogenates showed that quinone reductase activity was stimulated greater than 70% and 90%, respectively, over the control cells. This observed activity was sensitive to dicumarol, a potent inhibitor of quinone reductase activity. 1,2-Naphthoquinone- and beta-naphthoflavone-exposed cells were found to exhibit 1.47- and 1.68-fold increases, respectively, in zeta-crystallin protein concentration. A comparable increase in zeta-crystallin mRNA was indicative of an induction in zeta-crystallin expression in response to naphthalene challenge. Lens epithelial cells were also checked for DT-diaphorase, a well-known cellular protective enzyme which can catalyze the two-electron reduction of quinones. Slot blot analyses indicated that alpha TN4 cells exposed to 1,2-naphthoquinone and beta-naphthoflavone exhibited 2.71- and 6.81-fold increases in DT-diaphorase concentration when compared to the control cells. The data suggest that while DT-diaphorase is most likely responsible for the majority of the observed increase in quinone reductase activity, the zeta-crystallin gene also undergoes activation which is apparently mediated by a xenobiotic-responsive element.
...
PMID:Xenobiotic induction of quinone oxidoreductase activity in lens epithelial cells. 826 8


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---