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:2.5.1.18 (glutathione S-transferase)
22,582 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The 5'-cap structure of eukaryotic mRNA is methylated at the terminal guanosine by RNA (guanine-N7-)-methyltransferase (cap MTase). Saccharomyces cerevisiae ABD1 (ScABD1) and human hMet (also called CMT1) genes are responsible for this enzyme. The ABD1 homologue was cloned from the pathogenic fungus Candida albicans and named C. albicans ABD1 (CaABD1). When expressed as a fusion with glutathione S-transferase (GST), CaAbd1p displayed cap MTase activity in vitro and rescued S. cerevisiae abd1delta null mutants, indicating that CaABD1 specifies an active cap MTase. Although the human cap MTase binds to the human capping enzyme (Hce1p), which possesses both mRNA guanylyltransferase (mRNA GTase) and mRNA 5'-triphosphatase (mRNA TPase) activities, yeast two-hybrid analysis demonstrated that in yeast neither mRNA GTase nor mRNA TPase physically interacted with the Abd1 protein. Comparison of the amino acid sequences of known and putative cap MTases revealed a highly conserved amino acid sequence motif, Phe/Val-Leu-Asp/Glu-Leu/Met-Xaa-Cys-Gly-Lys-Gly-Gly-Asp-Leu-Xaa-Lys, which encompasses the sequence motif characteristic of divergent methyltransferases. Mutations in CaAbd1p of leucine at the second and the twelfth positions (so far uncharacterized) to alanine severely diminished the enzyme activity and the functionality in vivo, whereas those of leucine at the fourth, cysteine at the sixth, lysine at the eighth, and glycine at the tenth positions did not. Furthermore, valine substitution for the twelfth, but not for the second, leucine in that motif abolished the activity and functionality of CaAbd1p. Thus, it appears that leucine at the second and the twelfth positions in the motif, together with a previously identified acidic residue in the third, glycine at the sixth and glutamic acid at the eleventh positions, play important roles in the catalysis, and that side chain length is crucial for the activity at the twelfth position in the motif.
...
PMID:The Candida albicans gene for mRNA 5-cap methyltransferase: identification of additional residues essential for catalysis. 1058 10

Promoter hypermethylation is an important pathway for repression of gene transcription in cancer cells. We analyzed aberrant DNA methylation at four genes in primary tumors from 95 head and neck cancer patients and then used the presence of this methylation as a marker for cancer cell detection in serum DNA. These four genes were tested by methylation-specific PCR and included: p16 (CDKN2A), O6-methylguanine-DNA-methyltransferase, glutathione S-transferase P1, and death-associated protein kinase (DAP-kinase). Fifty-five % (52 of 95) of the primary tumors displayed promoter hypermethylation in at least one of the genes studied: 27% (26/95) at p16, 33% (31 of 95) at O6-methylguanine-DNA-methyltransferase; and 18% (17 of 92) at DAP-kinase. No promoter hypermethylation was observed at the glutathione S-transferase P1 gene promoter. We detected a statistically significant correlation between the presence of DAP-kinase gene promoter hypermethylation and lymph node involvement (P = 0.014) and advanced disease stage (P = 0.016). In 50 patients with paired serum available for epigenetic analysis, the same methylation pattern was detected in the corresponding serum DNA of 21 (42%) cases. Among the patients with methylated serum DNA, 5 developed distant metastasis compared with the occurrence of metastasis in only 1 patient negative for serum promoter hypermethylation (P = 0.056). Promoter hypermethylation of key genes in critical pathways is common in head and neck cancer and represents a promising serum marker for monitoring affected patients.
...
PMID:Gene promoter hypermethylation in tumors and serum of head and neck cancer patients. 1070 1

Type I protein arginine methyltransferases catalyze the formation of asymmetric omega-N(G),N(G)-dimethylarginine residues by transferring methyl groups from S-adenosyl-L-methionine to guanidino groups of arginine residues in a variety of eucaryotic proteins. The predominant type I enzyme activity is found in mammalian cells as a high molecular weight complex (300-400 kDa). In a previous study, this protein arginine methyltransferase activity was identified as an additional activity of 10-formyltetrahydrofolate dehydrogenase (FDH) protein. However, immunodepletion of FDH activity in RAT1 cells and in murine tissue extracts with antibody to FDH does not diminish type I methyltransferase activity toward the methyl-accepting substrates glutathione S-transferase fibrillarin glycine arginine domain fusion protein or heterogeneous nuclear ribonucleoprotein A1. Similarly, immunodepletion with anti-FDH antibody does not remove the endogenous methylating activity for hypomethylated proteins present in extracts from adenosine dialdehyde-treated RAT1 cells. In contrast, anti-PRMT1 antibody can remove PRMT1 activity from RAT1 extracts, murine tissue extracts, and purified rat liver FDH preparations. Tissue extracts from FDH(+/+), FDH(+/-), and FDH(-/-) mice have similar protein arginine methyltransferase activities but high, intermediate, and undetectable FDH activities, respectively. Recombinant glutathione S-transferase-PRMT1, but not purified FDH, can be cross-linked to the methyl-donor substrate S-adenosyl-L-methionine. We conclude that PRMT1 contributes the major type I protein arginine methyltransferase enzyme activity present in mammalian cells and tissues.
...
PMID:PRMT1 is the predominant type I protein arginine methyltransferase in mammalian cells. 1071 84

The heterogeneous nuclear ribonucleoproteins (hnRNP) associate with pre-mRNA in the nucleus and play an important role in RNA processing and splice site selection. In addition, hnRNP A proteins function in the export of mRNA to the cytoplasm. Although the hnRNP A proteins are predominantly nuclear, hnRNP A1 shuttles rapidly between the nucleus and the cytoplasm. HnRNP A2, whose cytoplasmic overexpression has been identified as an early biomarker of lung cancer, has been less well studied. Cytosolic hnRNP A2 overexpression has also been noted in brain tumors, in which it has been correlated with translational repression of Glucose Transporter-1 expression. We now examine the role of arginine methylation on the nucleocytoplasmic localization of hnRNP A2 in the HEK-293 and NIH-3T3 mammalian cell lines. Treatment of either cell line with the methyltransferase inhibitor adenosine dialdehyde dramatically shifts hnRNP A2 localization from the nuclear to the cytoplasmic compartment, as shown both by immunoblotting and by immunocytochemistry. In vitro radiolabeling with [(3)H]AdoMet of GST-tagged hnRNP A2 RGG mutants, using recombinant protein arginine methyltransferase (PRMT1), shows (i) that hnRNP A2 is a substrate for PRMT1 and (ii) that methylated residues are found only in the RGG domain. Deletion of the RGG domain (R191-G253) of hnRNP A2 results in a cytoplasmic localization phenotype, detected both by immunoblotting and by immunocytochemistry. These studies indicate that the RGG domain of hnRNP A2 contains sequences critical for cellular localization of the protein. The data suggest that hnRNP A2 may contain a novel nuclear localization sequence, regulated by arginine methylation, that lies in the R191-G253 region and may function independently of the M9 transportin-1-binding region in hnRNP A2.
...
PMID:The RGG domain in hnRNP A2 affects subcellular localization. 1077 24

Cytochromes c from plants and fungi, but not higher animals, contain methylated lysine residues at specific positions, including for example, the trimethylated lysine at position 72 in iso-1-cytochrome c of the yeast Saccharomyces cerevisiae. Testing of 6,144 strains of S. cerevisiae, each overproducing a different open reading frame fused to glutathione S-transferase, previously revealed that YHR109w was associated with an activity that methylated horse cytochrome c. We show here that this open reading frame, denoted Ctm1p, is specifically responsible for trimethylating lysine 72 of iso-1-cytochrome c. Unmethylated forms of cytochrome c but not other proteins or nucleic acids are methylated in vitro by Ctm1p produced in S. cerevisiae or Escherichia coli. Iso-1-cytochrome c purified from a ctm1-Delta strain is not trimethylated in vivo, whereas the K72R mutant form, or the trimethylated Lys-72 form of iso-1-cytochrome c, are not significantly methylated by Ctm1p in vitro. Like apocytochrome c, but in contrast to holocytochrome c, Ctm lp is located in the cytosol, consistent with the view that the natural substrate is apocytochrome c. The ctm1-Delta strain lacking the methyltransferase did not exhibit any growth defect on a variety of media and growth conditions, and the unmethylated iso-1-cytochrome c was produced at the normal level and exhibited the normal activity in vivo. Ctm1p and cytochrome c were coordinately regulated during anaerobic to aerobic transition, a finding consistent with the view that this methyltransferase evolved to act on cytochrome c.
...
PMID:Cytochrome c methyltransferase, Ctm1p, of yeast. 1079 61

The presence of 5-methyluridine (m5U) at position 54 is a ubiquitous feature of most bacterial and eukaryotic elongator tRNAs. In this study, we have identified and characterized the TRM2 gene that encodes the tRNA(m5U54)methyltransferase, responsible for the formation of this modified nucleoside in Saccharomyces cerevisiae. Transfer RNA isolated from TRM2-disrupted yeast strains does not contain the m5U54 nucleoside. Moreover, a glutathione S-transferase (GST) tagged recombinant, Trm2p, expressed in Escherichia coli displayed tRNA(m5U54)methyltransferase activity using as substrate tRNA isolated from a trm2 mutant strain, but not tRNA isolated from a TRM2 wild-type strain. In contrast to what is found for the tRNA(m5U54)methyltransferase encoding gene trmA+ in E. coli, the TRM2 gene is not essential for cell viability and a deletion strain shows no obvious phenotype. Surprisingly, we found that the TRM2 gene was previously identified as the RNC1/NUD1 gene, believed to encode the yNucR endo-exonuclease. The expression and activity of the yNucR endo-exonuclease is dependent on the RAD52 gene, and does not respond to increased gene dosage of the RNC1/NUD1 gene. In contrast, we find that the expression of a trm2-LacZ fusion and the activity of the tRNA(m5U54)methyltransferase is not regulated by the RAD52 gene and does respond on increased gene dosage of the TRM2 (RNC1/NUD1) gene. Furthermore, there was no nuclease activity associated with a GST-Trm2 recombinant protein. The purified yNucR endo-exonuclease has been reported to have an NH2-D-E-K-N-L motif, which is not found in the Trm2p. Therefore, we suggest that the yNucR endo-exonuclease is encoded by a gene other than TRM2.
...
PMID:Identification of the TRM2 gene encoding the tRNA(m5U54)methyltransferase of Saccharomyces cerevisiae. 1086 43

Aberrant methylation of CpG islands acquired in tumor cells in promoter regions is one method for loss of gene function. We determined the frequency of aberrant promoter methylation (referred to as methylation) of the genes retinoic acid receptor beta-2 (RARbeta), tissue inhibitor of metalloproteinase 3 (TIMP-3), p16INK4a, O6-methylguanine-DNA-methyltransferase (MGMT), death-associated protein kinase (DAPK), E-cadherin (ECAD), p14ARF, and glutathione S-transferase P1 (GSTP1) in 107 resected primary non-small cell lung cancers (NSCLCs) and in 104 corresponding nonmalignant lung tissues by methylation-specific PCR. Methylation in the tumor samples was detected in 40% for RARbeta, 26% for TIMP-3, 25% for p16INK4a, 21% for MGMT, 19% for DAPK, 18% for ECAD, 8% for p14ARF, and 7% for GSTP1, whereas it was not seen in the vast majority of the corresponding nonmalignant tissues. Moreover, p16INK4a methylation was correlated with loss of p16INK4a expression by immunohistochemistry. A total of 82% of the NSCLCs had methylation of at least one of these genes; 37% of the NSCLCs had one gene methylated, 22% of the NSCLCs had two genes methylated, 13% of the NSCLCs had three genes methylated, 8% of the NSCLCs had four genes methylated, and 2% of the NSCLCs had five genes methylated. Methylation of these genes was correlated with some clinicopathological characteristics of the patients. In comparing the methylation patterns of tumors and nonmalignant lung tissues from the same patients, there were many discordancies where the genes methylated in nonmalignant tissues were not methylated in the corresponding tumors. This suggests that the methylation was occurring as a preneoplastic change. We conclude that these findings confirm in a large sample that methylation is a frequent event in NSCLC, can also occur in smoking-damaged nonmalignant lung tissues, and may be the most common mechanism to inactivate cancer-related genes in NSCLC.
...
PMID:Aberrant promoter methylation of multiple genes in non-small cell lung cancers. 1119 70

Common variable immunodeficiency (CVI) patients are at high relative risk of developing non-Hodgkin lymphomas (NHL), mainly represented by B-lineage diffuse large cell lymphomas. The molecular pathogenesis and histogenesis of CVI-related NHL are poorly understood. We have thus attempted to provide a detailed molecular characterization of their histogenesis and pathogenesis. A panel of 5 CVI-related NHL was subjected to detailed analysis of histogenetic markers (mutations of immunoglobulin variable heavy chain-IgVH and of BCL-6 genes) acquired by B-cells at the time of germinal center transit. Somatic hypermutation of IgVH and BCL-6 genes occurred in 5/5 cases; in all cases, mutations were stable with no evidence of ongoing mutation processes. In 3/5 cases, the pattern of IgVH mutations was consistent with selection and stimulation of the tumor clone by antigen. To further clarify the pathogenesis, samples were tested for inactivation by promoter hypermethylation of the genes 0(6)-methylguanine-DNA-methyltransferase (MGMT) and glutathione S-transferase (GST) p1, which code for detoxifying enzymes, as well as of death-associated protein (DAP)-kinase, coding for a proapoptotic molecule. Promoter hypermethylation of MGMT, GSTp1 and DAP-kinase was detected in 2/5, 3/5 and 3/5 CVI-related NHL, respectively. Overall, these data indicate that: i) similarly to other immunodeficiency-related NHL, CVI-related NHL derive from germinal center-related B-cells, namely centrocytes or post-germinal center B-cells; ii) antigen stimulation and selection are involved in the development of at least a fraction of these cases; iii) hypermethylation of the MGMT, DAP-kinase and GSTp1 genes occurs at sustained frequencies in CVI-related NHL and may provide novel prognostic markers and therapeutic targets for the clinical management of these lymphomas.
...
PMID:Molecular characterization of common variable immunodeficiency-related lymphomas. 1169 5

The ets-related gene erg encodes a transcription factor that is implicated in the control of cell growth and differentiation. To identify interacting partners of ERG, we screened a yeast two-hybrid cDNA library constructed from mouse hematopoietic cells using the N-terminal region of ERG as a bait. We isolated a 4.6 kb full-length mouse cDNA encoding a 1307-amino acid protein migrating as a 180 kD band, which was termed ESET (ERG-associated protein with SET domain). ESET is 92% identical to the human protein SETDB1 (SET domain, bifurcated 1). The interaction between ESET and ERG was supported by in vitro pull-down using glutathione S-transferase (GST) fusion protein, by transfection and co-immunoprecipitation experiments, and by association of endogenous SETDB1 with ERG. Since ESET possesses evolutionarily conserved SET, preSET, and postSET domains implicated in histone methylation, we tested the ability of ESET to methylate core histones. The results of these studies demonstrated that ESET is a histone H3-specific methyltransferase, and that mutations within ESET abolished its methyltransferase activity. Together, these findings raise the possibility that transcription factor ERG may participate in transcriptional regulation through ESET-mediated histone methylation.
...
PMID:Molecular cloning of ESET, a novel histone H3-specific methyltransferase that interacts with ERG transcription factor. 1179 Nov 85

During the pathogenesis of human hepatocellular carcinoma (HCC), the CpG island encompassing the pi-class glutathione S-transferase gene (GSTP1) becomes hypermethylated. Repression of transcription accompanying CpG island hypermethylation has been proposed to be mediated by methyl-CpG binding domain (MBD) proteins. We report here that inhibition of transcription from hypermethylated GSTP1 promoters in Hep3B HCC cells, which fail to express GSTP1 mRNA or GSTP1 polypeptides, appears to be mediated by MBD2. Treatment of Hep3B cells with 5-azadeoxycytidine (5-aza-dC), a methyltransferase inhibitor, activated GSTP1 expression, whereas treatment with trichostatin A, a histone deacetylase inhibitor, had little effect. To more precisely assess the contribution of the pattern of GSTP1 CpG island methylation on GSTP1 mRNA expression, Hep3B cells were treated for 72 h with 5-aza-dC and then subjected to limiting dilution cloning. Bisulfite sequencing was used to map the methylation patterns of the GSTP1 promoter region in GSTP1-expressing and -non-expressing clones. In the clone that expressed GSTP1 mRNA determined by Northern blot analysis and quantitative reverse transcriptase (RT)-PCR, widespread demethylation of at least one GSTP1 allele was evident. Chromatin immunoprecipitation experiments revealed the presence of MBD2, but not Sp1, at the GSTP1 promoter in Hep3B cells. In contrast, Sp1 was detected at the GSTP1 promoter in a GSTP1-expressing Hep3B 5-aza-dC subclone. To test whether MBD2 might be responsible for the inhibition of GSTP1 transcription from hypermethylated GSTP1 promoters, siRNAs were used to reduce MBD2 polypeptide levels in Hep3B cells. SssI-catalyzed methylation of GSTP1 promoter sequences resulted in diminished luciferase reporter activity after transfection into Hep3B cells. However, when hypermethylated GSTP1 promoter sequences were transfected into Hep3B cells that had been treated with siRNA-targeting MBD2 mRNA, no repression of luciferase reporter expression was evident. These findings implicate MBD2 in the repression of GSTP1 expression associated with GSTP1 CpG island hypermethylation in HCC cells.
...
PMID:Methyl-CpG binding domain protein 2 represses transcription from hypermethylated pi-class glutathione S-transferase gene promoters in hepatocellular carcinoma cells. 1196 Sep 94


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

---