Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.1.1.17 (ornithine decarboxylase)
 6,351 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The constituent amino acids of reduced glutathione (GSH), GSH itself, and D-alpha-tocopherol inhibited 12-O-tetradecanoyl-phorbol-13-acetate (TPA)-induced ornithine decarboxylase (ODC, L-ornithine carboxy-lyase, EC 4.1.1.17) activity in mouse epidermis in vivo and in vitro. The inhibitory effects of cysteine (Cys), GSH and D-alpha-tocopherol on ODC induction were proportional to their abilities to decrease the incidence of skin tumors in the initiation-promotion protocol. Moreover, the ability of the constituent amino acids of GSH and GSH to inhibit TPA-induced ODC activity correlated well with their ability to increase the ratio of GSH/oxidized glutathione (GSSG) in isolated epidermal cells. In vitro, various treatments with 1 mM GSH, 1 mM glutamic acid (Glu), 1 mM glycine (Gly), 0.4 mM Cys and/or 0.2 mM cystine (CysCys) inhibited dramatically the sharp decline in the intracellular ratio of GSH/GSSG caused by 0.1 microM TPA. Since the inhibitory effects of Cys on both the decrease in the ratio of GSH/GSSG and the induction of ODC activity by TPA were greatly reduced by the inhibitors of gamma-glutamyl transpeptidase and gamma-glutamylcysteine synthetase, it is suggested that some of the inhibitory effects of Glu, Cys and Gly on tumor promotion could result from their interference with the metabolism of the tripeptide GSH, a natural antioxidant which inhibits chemical carcinogenesis. The free radical scavenger D-alpha-tocopherol, which did not alter directly the intracellular ratio of GSH/GSSG, also prevented completely the decrease in the ratio of GSH/GSSG caused by TPA. These results, therefore, suggest that GSH level-raising agents and other antioxidants might inhibit by diverse means the effects of TPA on GSH metabolism and skin tumor promotion.
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PMID:Inhibitory effects of glutathione level-raising agents and D-alpha-tocopherol on ornithine decarboxylase induction and mouse skin tumor promotion by 12-O-tetradecanoylphorbol-13-acetate. 285 27

The induction of ornithine decarboxylase (ODC) activity in lymphocytes is associated with activation and the initiation of cellular proliferation. ODC is also an essential component in tumor promotion. Phorbol myristic acetate (PMA) is a mitogen for lymphocytes, but can also promote tumor formation. Tumor promotion is linked to the generation of free radicals induced by PMA. Modulation of intracellular glutathione is associated lymphocyte activation and in protection of cells from damage due to oxygen radicals. We examined the interaction between ODC activity and intracellular glutathione concentrations in EL4 murine lymphoblastoid cells. The intracellular glutathione concentration could be augmented in EL4 cells when cultured with the cysteine delivery agents 2-oxothiazolidine 4-carboxylate (OTC) and 2-mercaptoethanol (2-ME) and suppressed with the gamma-glutamylcysteine synthetase inhibitor buthionine sulfoximine (BSO). OTC and 2-ME suppressed ODC activity in fresh serum and PMA-activated EL4 cells. BSO had no effect on ODC activity of EL4 cells cultured in the presence of PMA. While both OTC and 2-ME augmented the total intracellular glutathione concentration, PMA enhanced only the level of oxidized glutathione. To determine if the mechanism by which PMA or fresh serum altered intracellular glutathione and ODC activity was through the generation of oxygen radicals, EL4 cells were cultured with free radical scavengers. The nonpermeant electron acceptor potassium ferricyanide, and the H2O2 scavenger catalase, lowered ODC activity in both serum-stimulated and PMA-activated EL4 cells. Similarly, incubation of EL4 cells with either potassium ferricyanide or catalase elevated intracellular glutathione concentrations. These data suggest that (a) modulation of intracellular glutathione in the EL4 lymphoblastoid cell line alters ODC activity induced by fresh serum and by the mitogen PMA; (b) activation of EL4 cells by PMA alone alters intracellular glutathione metabolism, which may be associated with its role as a mitogen in lymphocyte activation; and (c) the generation of free radicals in EL4 cells may play a positive role in cellular activation.
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PMID:The generation of oxygen radicals: a positive signal for lymphocyte activation. 336 70

We have examined the effect of chemically modulating intracellular glutathione (GSH) levels on murine lymphocyte activation. Lymphocyte activation was determined by the induction of polyamine synthesis (ornithine decarboxylase (ODC) induction) and DNA synthesis ([3H]thymidine([3H]Tdr) incorporation). Intracellular GSH levels were enhanced using L-2-oxothiazolidine-4-carboxylate (OTC), which delivers cysteine intracellularly, and suppressed by buthionine sulfoximine (BSO), which inhibits gamma-glutamylcysteine synthetase. In addition, the thiol 2-mercaptoethanol (2-ME) was tested for its ability to augment intracellular GSH levels. Our results indicate that both OTC and 2-ME enhance GSH concentrations and [3H]Tdr incorporation in resting and mitogen (concanavalin A)-stimulated cells. The induction of ODC by concanavalin A (Con A) was augmented by the addition of OTC or 2-ME. The GSH concentration of Con A-stimulated cells was reduced when compared to resting cells; however, it was markedly enhanced by OTC or 2-ME. The stimulatory effects of 2-ME on GSH concentrations, [3H]Tdr incorporation, and ODC induction in both resting and Con A-stimulated cells were much more potent than those of OTC. In contrast, BSO suppressed intracellular GSH and [3H]Tdr incorporation in resting and Con A-stimulated cells. BSO also inhibited the promotion of intracellular GSH concentrations and [3H]Tdr uptake by OTC or 2-ME. However, BSO did not affect the induction of ODC by Con A or its enhancement by OTC or 2-ME. We conclude that enhancement of intracellular GSH concentration results in an increased lymphocyte response to mitogen stimulation.
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PMID:Enhancement of intracellular glutathione promotes lymphocyte activation by mitogen. 374 7

Trypanothione is the key molecule in the defence mechanism of Trypanosoma and Leishmania against oxidative stress. The uniqueness of trypanothione makes the metabolism of this molecule an attractive target in antitrypanosomal and antileishmanial drug design. It became clear that this antioxidant cascade can be considered as the "Achilles heel" of these parasites. The following targets and their respective inhibitors will be discussed: biosynthesis of trypanothione with glutathionylspermidine synthetase and trypanothione synthetase; biosynthesis of glutathione with gamma-glutamylcysteine synthetase; biosynthesis of spermidine with ornithine decarboxylase; trypanothione hydroperoxide metabolism with tryparedoxine peroxidase, tryparedoxine and trypanothione reductase.
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PMID:Trypanothione as a target in the design of antitrypanosomal and antileishmanial agents. 1147 57

Gene expression of human ovarian carcinoma cell lines and epithelial ovarian tumors was examined by oligonucleotide microarray for about 6000 human cDNAs. (1) Comparison of gene expression between CDDP-sensitive human ovarian serous adenocarcinoma cell lines and CDDP-resistant cell lines revealed that gamma-glutamylcysteine synthetase, glutathione peroxidase-like protein, dehydrogenase (UGDH), NAD(P)H: quinoneoxireductase, glucose-6-phosphatase, ornithine decarboxylase and dihydrodiol dehydrogenase were associated with a mechanism of CDDP-resistance. Comparison of gene expression between taxol-sensitive human ovarian cell lines and taxol-resistant cell lines showed that up-regulation of 30 kinds of gene expression including MDR and semaphorin E in taxol-resistant cell lines. (2) Comparison of gene expression among serous adenocarcinomas, clear cell adenocarcinomas and non-cancerous ovarian tissues by hierarchical clustering demonstrated that clear difference between carcinomas and non-cancerous ovarian tissues but not obvious difference between serous and clear adenocarcinomas. Genes that were up- and down-regulated specifically in these two types of ovarian carcinomas were further selected by the criteria that difference in the mRNA level by more than 4-fold between tumors and non-cancerous tissues. Tissue type specific alterations of gene expression are likely to play important roles in the carcinogenesis of epithelial ovarian tumors. cDNA microarray is a powerful and high-throughput tool to analyze gene expression of cancer development.
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PMID:[Gene expression profiling of human ovarian epithelial tumors by digo nucleotide microarray]. 1192 26

Trypanothione plays a pivotal role in defence against chemical and oxidant stress, thiol redox homoeostasis, ribonucleotide metabolism and drug resistance in parasitic kinetoplastids. In Trypanosoma brucei, trypanothione is synthesized from glutathione and spermidine by a single enzyme, TryS (trypanothione synthetase), with glutathionylspermidine as an intermediate. To examine the physiological roles of trypanothione, tetracycline-inducible RNA interference was used to reduce expression of TRYS. Following induction, TryS protein was reduced >10-fold and growth rate was reduced 2-fold, with concurrent 5-10-fold decreases in glutathionylspermidine and trypanothione and an up to 14-fold increase in free glutathione content. Polyamine levels were not significantly different from non-induced controls, and neither was the intracellular thiol redox potential, indicating that these factors are not responsible for the growth defect. Compensatory changes in other pathway enzymes were associated with prolonged suppression of TryS: an increase in trypanothione reductase and gamma-glutamylcysteine synthetase, and a transient decrease in ornithine decarboxylase. Depleted trypanothione levels were associated with increases in sensitivity to arsenical, antimonial and nitro drugs, implicating trypanothione metabolism in their mode of action. Escape mutants arose after 2 weeks of induction, with all parameters, including growth, returning to normal. Selective inhibitors of TryS are required to fully validate this novel drug target.
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PMID:Phenotypic analysis of trypanothione synthetase knockdown in the African trypanosome. 1600 27

Control of visceral leishmaniasis (VL) is being challenged by the emergence of natural resistance against the first line of treatment, pentavalent antimonials [Sb(V)]. An insight into the mechanism of natural Sb(V) resistance is required for the development of efficient strategies to monitor the emergence and spreading of Sb(V) resistance in countries where VL is endemic. In this work, we have focused on the mechanism of natural Sb(V) resistance emerging in Nepal, a site where anthroponotic VL is endemic. Based on the current knowledge of Sb(V) metabolism and of the in vitro trivalent antimonial [Sb(III)] models of resistance to Leishmania spp., we selected nine genes for a comparative transcriptomic study on natural Sb(V)-resistant and -sensitive Leishmania donovani isolates. Differential gene expression patterns were observed for the genes coding for 2-thiol biosynthetic enzymes, gamma-glutamylcysteine synthetase (GCS) and ornithine decarboxylase (ODC), and for the Sb(III) transport protein aquaglyceroporin 1 (AQP1). The results indicate that the mechanism for natural Sb(V) resistance partially differs from the mechanism reported for in vitro Sb(III) resistance. More specifically, we hypothesize that natural Sb(V) resistance results from (i) a changed thiol metabolism, possibly resulting in inhibition of Sb(V) activation in amastigotes, and (ii) decreased uptake of the active drug Sb(III) by amastigotes.
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PMID:Gene expression analysis of the mechanism of natural Sb(V) resistance in Leishmania donovani isolates from Nepal. 1625 3