Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.5.1.18 (glutathione S-transferase)
 22,582 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In order to investigate the early cellular changes in liver associated with furan cholangiocarcinogenesis, young adult male Fischer 344 rats were administered furan by gavage once a day, 5 days a wk for 2 to 3 wk at doses ranging from 15 to 60 mg/kg of body weight per day. The most conspicuous feature observed in the liver of animals receiving the higher doses of furan was a rapidly developed cholangiofibrosis characterized by the presence of bile ductular hyperplasia, intestinal metaplasia, and fibrosis. Moreover, this lesion was found to be almost exclusively localized to the caudate liver lobe, which by morphometric analysis was further determined to be largely replaced by cholangiofibrotic tissue. Both the hyperplastic bile ductular epithelial cells and the intestinal-like epithelial cells in these areas selectively exhibited a strongly positive immunohistochemical staining for cytokeratin 19 and were supported by well-developed basement membranes enriched in both laminin and type IV collagen. However, in contrast to the hyperplastic bile ductules, electron microscopy of the metaplastic intestinal glands revealed them to be composed mostly of columnar epithelial cells with well-developed striated borders, less numerous mucin-secreting goblet cells, and occasional neuroendocrine-like cells, thus closely resembling in their cellular composition that of intestinal mucosa. These metaplastic glands also showed a more heterogeneous pattern of staining for both gamma-glutamyl transpeptidase and the placental form of glutathione S-transferase than did the hyperplastic bile ductules. At the 60-mg/kg/day furan dose, cholangiolar-like structures composed of biliary epithelial cells and ductular hepatocytic cells at different stages of morphological differentiation were also observed. Phenotypically, the biliary epithelial and "ductular hepatocytes" of these cholangioles shared a common basement membrane containing laminin and type IV collagen, as well as a luminal plasma membrane gamma-glutamyl transpeptidase. On the other hand, only the biliary epithelial cells of the newly appearing mixed cell cholangioles stained positive for cytokeratin 19. Interestingly, unlike hepatocarcinogen-induced oval cells, alpha-fetoprotein expression was not detected in any of the cell types comprising the furan-induced cholangiofibrotic tissue. These results support a novel in vivo model for investigating cell lineages in the development in liver of intestinal metaplasia, "ductular hepatocytes," and cholangiofibrosis in relation to intrahepatic cholangiocarcinogenesis.
 ...
PMID:Phenotypic characterization of metaplastic intestinal glands and ductular hepatocytes in cholangiofibrotic lesions rapidly induced in the caudate liver lobe of rats treated with furan. 165 60

Human placental form of glutathione S-transferase (GST-pi) was detected in human colonic carcinomas and adenomas by peroxidase anti-peroxidase method using antibody raised against GST-pi. Of 60 carcinomas, including differentiated adenocarcinomas and undifferentiated carcinomas, 88% were positive for GST-pi staining, and 47% of 23 adenomas were also positive. In the normal colonic mucosa, GST-pi was not detectable or was only weakly stained in the basal parts of the absorptive cells or in the cytoplasm of the cells containing little mucin. These results indicate that GST-pi is a possible new marker for immunohistochemical detection of human colonic carcinoma and some adenomas.
 ...
PMID:Human placental form of glutathione S-transferase (GST-pi) as a new immunohistochemical marker for human colonic carcinoma. 308 12

Antibodies recognising the products of alternatively spliced exons near the N-terminus of the leukocyte common antigen, CD45, have been widely used to distinguish populations of lymphocytes with different functional properties. These alternatively spliced regions contain a high content of serine and threonine residues (average 35%) and are heavily O-glycosylated. Despite evidence that the O-glycosylation contributes significantly to the antigenic character of this region of CD45, work with leukosialin and mucin glycoproteins leads to the prediction that the majority of epitopes in the N-terminal exons should be linear protein determinants. In this study the exons of CD45 were expressed in Escherichia coli as non-glycosylated proteins fused to glutathione S-transferase (GST). Fourteen out of 17 mAbs specific for human CD45R reacted with a fusion protein containing exons 4, 5 and 6 (ABC) of human CD45, and four out of six mAbs specific for rat CD45R reacted with an equivalent rat protein. mAbs recognising the product of rat exon B are reported for the first time. Kinetic analysis of MRC OX22 antibody binding to spleen CD45 and to GST fusion proteins showed that the carbohydrate affected the kinetics of binding of antibodies to the protein backbone. In conclusion, heterogeneity in the glycosylation of heavily O-glycosylated cell surface proteins can affect interactions of these proteins both directly through the carbohydrate and indirectly through effects on the protein backbone.
 ...
PMID:Antigenic determinants encoded by alternatively spliced exons of CD45 are determined by the polypeptide but influenced by glycosylation. 753 96

In an attempt to seek out new factors that are related to colorectal carcinogenesis at the molecular level, subtractive hybridization between cDNA of normal mucosal tissues and mRNA of colorectal carcinoma tissues was performed. Subsequent screenings of the cDNA libraries, constructed from normal mucosal tissues, using the "subtractive probes" generated a total of 46 clones that were expressed in normal mucosa but were either expressed at a significantly reduced level or not expressed at all in cancer tissues. Partial nucleotide sequences of all of these cDNA clones were determined, and sequence homology analyses were performed with the Genbank database. Of the 46 cDNA samples, 44 contained substantial sequence homologies with 32 immunoglobulin gene fragments, a helix-loop-helix basic phosphoprotein gene, an acidic ribosomal phosphoprotein P2 gene, a BLR1 gene for Burkitt's lymphoma receptor 1 gene, D5S419 DNA segment containing (C-A) repeats, a glucokinase (GCK) gene, a Na+, K+-ATPase alpha-subunit gene, a histocompatibility system HLA-DR heavy-chain gene, a dystrophic gene, a mucin (MUC2) gene, a mu-glutathione S-transferase gene, a Menkes disease protein gene, and a 40-kDa keratin intermediate filament precursor gene. The remaining two cDNA clones (now registered under GenBank accession numbers U17714 and U20428) showed few (less than 60%) sequence homologies with any known sequences in the GenBank database and, therefore, may represent novel genes whose expression was down-regulated in human colorectal carcinomas. The possible clinical significance of these findings and the involvement of these two genes in the carcinogenesis of colorectal as well as other cancers are being investigated.
 ...
PMID:Characterization of colorectal-cancer-related cDNA clones obtained by subtractive hybridization screening. 929 8

The hepatitis A virus cellular receptor 1 (HAVcr-1) cDNA codes for a class I integral membrane glycoprotein, termed havcr-1, of unknown natural function which serves as an African green monkey kidney (AGMK) cell receptor for HAV. The extracellular domain of havcr-1 has an N-terminal Cys-rich region that displays homology with sequences of members of the immunoglobulin superfamily, followed by a Thr/Ser/Pro (TSP)-rich region characteristic of mucin-like O-glycosylated proteins. The havcr-1 glycoprotein contains four putative N-glycosylation sites, two in the Cys-rich region and two in the TSP-rich region. To characterize havcr-1 and define region(s) involved in HAV receptor function, we expressed the TSP-rich region in Escherichia coli fused to glutathione S-transferase and generated antibodies (Ab) in rabbits (anti-GST2 Ab). Western blot analysis with anti-GST2 Ab detected 62- and 65-kDa bands in AGMK cells and 59-, 62-, and 65-kDa bands in dog cells transfected with the HAVcr-1 cDNA (cr5 cells) but not in dog cells transfected with the vector alone (DR2 cells). Treatment of AGMK and cr5 cell extracts with peptide-N-glycosidase F resulted in the collapse of the havcr-1-specific bands into a single band of 56 kDa, which indicated that different N-glycosylated forms of havcr-1 were expressed in these cells. Treatment of AGMK and cr5 cells with tunicamycin reduced binding of protective monoclonal Ab (MAb) 190/4, which suggested that N-glycans are required for binding of MAb 190/4 to havcr-1. To test this hypothesis, havcr-1 mutants lacking the N-glycosylation motif at the first site (mut1), second site (mut2), and both (mut3) sites were constructed and transfected into dog cells. Binding of MAb 190/4 and HAV to mut1 and mut3 cells was highly reduced, while binding to mut2 cells was not affected and binding to dog cells expressing an havcr-1 construct containing a deletion of the Cys-rich region (d1- cells) was undetectable. HAV-infected cr5 and mut2 cells but not mut1, mut3, d1-, and DR2 cells developed the characteristic cytoplasmic granular fluorescence of HAV-infected cells. These results indicate that the Cys-rich region of havcr-1 and its first N-glycosylation site are required for binding of protective MAb 190/4 and HAV receptor function.
 ...
PMID:The Cys-rich region of hepatitis A virus cellular receptor 1 is required for binding of hepatitis A virus and protective monoclonal antibody 190/4. 955 57

Intestinal N-acetylglucosamine 6-O-sulfotransferase (I-GlcNAc6ST, GST-4alpha) and corneal N-acetylglucosamine 6-O-sulfotransferases (C-GlcNAc6ST, GST-4beta) are two highly homologous GlcNAc 6-O-sulfotransferase isozymes encoded by two intronless open reading frames that reside approximately 50 kb apart on human chromosome 16q23.1. I-GlcNAc6ST has been shown to catalyze 6-O-sulfation of the endothelial mucin GlyCAM-1. C-GlcNAc6ST catalyzes 6-O-sulfation of GlcNAc in keratan sulfate and null-mutations in its encoding gene cause human macular corneal dystrophy. We show here that C-GlcNAc6ST efficiently catalyzes sulfation of GlyCAM-1 when coexpressed with the latter in COS-7 cells. We have further compared expression in human of both enzymes by Northern analysis with isozyme-specific probes. While I-GlcNAc6T is expressed mostly in intestinal tissue, larger C-GlcNAc6ST transcripts are found predominantly in the brain.
 ...
PMID:Sulfation of endothelial mucin by corneal keratan N-acetylglucosamine 6-O-sulfotransferase (GST-4beta). 1135 40

MUC1 mucin is a high molecular weight, type I transmembrane glycoprotein. High and aberrant expression of MUC1 is observed in various types of tumors, which make it an ideal target for tumor biotherapy as well as a biomarker for tumor diagnosis and prognosis. MUC1/Y is an isoform of MUC1 generated by alternative splicing. Specific expression of MUC1/Y in breast cancer as well as its involvement in tumor cell signal transduction have been reported. In order to purify peptides containing MUC1/Y-specific epitope in E. coli and prepare MUC1/Y-specific antibody, DNA fragment encoding the MUC1/Y-specific peptide was amplified by PCR using MUC1/Y full length cDNA as the template and cloned into fusion expression vector pGEX-2T, resulting pGEX-Y30. DNA sequencing was performed to confirm the correct amplification and orientation of the target sequence. Competent E. coli DH5alpha was transformed with pGEX-Y30 and the expression was induced for 4-5 hours in 0.2 mmol/L IPTG at 30 degrees C and 37 degrees C. Expressed proteins were released from the cells by ultrasonication or B-PER II reagent treatments. The fusion protein GST-Y30 were purified by affinity and anion exchange columns and identified by SDS-PAGE and Western-blotting. Polyclonal antibody was prepared by immunizing rabbits with the GST-Y30 protein for 4 times with intervals of 3 weeks and purified by GST column. Western blotting, ELISA and immunohistochemistry analysis were carried out using the purified antibody to confirm its MUC1/Y-binding capacity and specificity. The expressed fusion protein GST-Y30 is about 31 kD in size and represented about 20% of total cellular proteins. The majority of the GST-Y30 protein existed as soluble form when the induction was carried out at both 30 degrees C and 37 degrees C. After the two-step purification, the purity of GST-Y30 was about 94%. The titer of polyserum generated by GST-Y30 immunization was 1:320,000 by ELISA. The antiserum showed MUC1/Y specificity and can recognize MUC1/Y on MCF7 cell. The MUC1/Y-specific polyclonal antibody can be used for studying the role of MUC1/Y in carcinogenesis.
 ...
PMID:[Soluble expression of peptide containing MUC1/Y-specific epitope in Escherichia coli and preparation of the antibody]. 1596 18

The targeting of epitopes on tumor-associated glycoforms of human MUC1 represents a primary goal in immunotherapeutic anticancer strategies. Effective immune responses to cancer cells certainly require the activation of specific cytotoxic T cell repertoires by cross-priming of dendritic cells either via immunoproteasomal or by endosomal processing of ectodomain epitopes on MUC1-positive carcinomas. Because no evidence is currently available on the capacities of human immunoproteasomes to cleave mucin-type O-glycosylated peptides, we performed in vitro studies to address the questions of whether glycosylated MUC1 repeats are cleaved by immunoproteasomes and in which way O-linked glycans control the site specificity of peptide cleavage via their localization and structures. We show for the first time that mucin-type O-glycosylated peptides are effective substrates of immunoproteasomes, however, the patterns of cleavage are qualitatively and quantitatively influenced by O-glycosylation. The nonglycosylated MUC1 repeat peptide (clusters of oligorepeats AHGVTSAPDTRPAPGSTAPP or AHGVTSAPESRPAPGSTAPA) is cleaved preferentially within or adjacent to the SAP and GST motifs with formation of a complex fragment pattern that includes major nona- and decapeptides. O-GalNAc modified peptides are largely resistant to proteolysis if these preferred cleavage sites are located adjacent to O-glycosylation, whereas peptides even with elongated glycans at more distant sites can form effective substrates yielding major glycopeptide fragments in the class I size range.
 ...
PMID:O-glycosylated human MUC1 repeats are processed in vitro by immunoproteasomes. 1767 99

Lactobacillus is a probiotic commonly used for supplementation to human and animal diets. In this study, we used 2-DE and MS to analyze changes in the proteomes of Lactobacillus and intestinal epithelial cells in two model systems. The in vivo and in vitro models were involved the inoculation of Lactobacillus fermentum I5007 into the rabbit jejunum for 4 h and the culture of the bacterium with Caco-2 cells for 1 h, respectively. Our results indicate that, after exposure to the intestinal environment, the bacterium exhibited decreases in key enzymes involved in energy metabolism (e.g., lactate dehydrogenase, dihydrolipoamide dehydrogenase, and nicotinate phosphoribosyltransferase) and amino acid metabolism (e.g., arginyl-tRNA synthetase and aspartate-semialdehyde dehydrogenase), but increases in glycoside hydrolase (an enzyme for mucin degradation) and fructose-6-phosphate phosphoketolase (an enzyme of the pentose phosphate pathway). In response to an interaction with L. fermentum I5007, Caco-2 cells showed changes in proteins that were beneficial for gut integrity, including voltage-dependent anion channel 1, glutathione transferase, and heat shock protein gp96. On the basis of their functions, we suggest that these proteins serve as useful biomarkers for metabolic changes in Lactobacillus and intestinal epithelial cells in response to their interactions.
 ...
PMID:2-DE and MS analysis of interactions between Lactobacillus fermentum I5007 and intestinal epithelial cells. 1800 11

Consumption of cruciferous vegetables has been associated with reduced colon cancer risk in human populations. However, little experimental evidence exists to support this association. Here, we report the effects of diets containing cruciferous vegetables on colon cancer risk. In Expt. 1, rats were fed a vegetable-free (basal) diet or diets containing different lyophilized cruciferous vegetables in concentrations between 4 and 10%. In Expt. 2, rats were fed the basal diet or diets containing 10-22.6% fresh cruciferous vegetables. Diets were fed for 2 wk (Expt. 1) or 3 wk (Expt. 2) before and 7 wk (Expt. 1) or 12 wk (Expt. 2) after administration of the colon carcinogen 1,2-dimethylhydrazine. Rats fed fresh vegetables were also injected with a low dose of carcinogen 18-24 h prior to termination. Groups fed lyophilized vegetables did not differ in aberrant crypt foci (ACF), sialomucin-producing foci, or mucin-depleted foci (MDF) numbers. However, all fresh vegetable diets significantly decreased ACF (approximately 40%) and MDF numbers. Activities of the hepatic phase I enzyme CYP2E1 did not differ among groups in either experiment. Hepatic glutathione S-transferase (GST) and quinone reductase activities did not differ among groups fed fresh vegetables, whereas the lyophilized cabbage diets decreased GST activity compared with the basal diet. Groups did not differ in apoptosis and cell proliferation labeling indices in colonic mucosa. This study indicates that fresh but not lyophilized cruciferous vegetables reduce colon cancer risk in rats. These results do not support changes in hepatic carcinogen metabolism or colonic crypt cytokinetics as a mechanism.
 ...
PMID:Cruciferous vegetables reduce morphological markers of colon cancer risk in dimethylhydrazine-treated rats. 1828 61


1 2 Next >>