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

One of the immediate cellular responses to stimulation by various growth factors is the activation of a phosphatidylinositol (PI) 3-kinase. We recently cloned the 85-kDa subunit of PI 3-kinase (p85) from a lambda gt11 expression library, using the tyrosine-phosphorylated carboxy terminus of the epidermal growth factor (EGF) receptor as a probe (E. Y. Skolnik, B. Margolis, M. Mohammadi, E. Lowenstein, R. Fischer, A. Drepps, A. Ullrich, and J. Schlessinger, Cell 65:83-90, 1991). In this study, we have examined the association of p85 with EGF and platelet-derived growth factor (PDGF) receptors and the tyrosine phosphorylation of p85 in 3T3 (HER14) cells in response to EGF and PDGF treatment. Treatment of cells with EGF or PDGF markedly increased the amount of p85 associated with EGF and PDGF receptors. Binding assays with glutathione S-transferase (GST) fusion proteins demonstrated that either Src homology region 2 (SH2) domain of p85 is sufficient for binding to EGF and PDGF receptors and that receptor tyrosine autophosphorylation is required for binding. Binding of a GST fusion protein expressing the N-terminal SH2 domain of p85 (GST-N-SH2) to EGF and PDGF receptors was half-maximally inhibited by 2 and 24 mM phosphotyrosine (P-Tyr), respectively, suggesting that the N-SH2 domain interacts more stably with PDGF receptors than with EGF receptors. The amount of receptor-p85 complex detected in HER14 cells treated with EGF or PDGF. Growth factor treatment also increased the amount of p85 found in anti-PDGF-treated HER14 cells, suggesting that the vast majority of p85 in the anti-P-Tyr fraction is receptor associated but not phosphorylated on tyrosine residues. Only upon transient overexpression of p85 and PDGF receptor did p85 become tyrosine phosphorylated. These are consistent with the hypothesis that p85 functions as an adaptor molecule that targets PI 3-kinase to activated growth factor receptors.
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PMID:Interaction of phosphatidylinositol 3-kinase-associated p85 with epidermal growth factor and platelet-derived growth factor receptors. 137 91

Alterations in cellular biochemistry which are associated with the development of resistance to cytotoxic peptides, such as tumor necrosis factor (TNF), may also be responsible for changes in the response of cells to cytotoxic agents. Culturing ME-180 cervical carcinoma cells in the presence of escalating concentrations of TNF resulted in the development of an ME-180 cell variant (ME-180R) resistant to TNF but expressing a 3-5-fold increased sensitivity to cisplatin (CDDP) when measured following continuous exposure (low doses) or short-term incubation with CDDP (high doses) and clonogenic analysis. Cellular platinum uptake, efflux, and nuclear platinum content as well as the extent of DNA platination were examined and found to be identical in both ME-180 parental and ME-180R cell lines. Although ME-180R cells showed a relatively higher glutathione content than ME-180 parental cells, the effect of buthionine sulfoximine on the cellular sensitivity to CDDP and glutathione S-transferase activities of both cell lines were almost identical, suggesting that glutathione content or its metabolism did not appear to play a major role in differential CDDP cytotoxicity. Unscheduled DNA synthesis following exposure to CDDP was more inducible in ME-180 parental cells than in CDDP-sensitive ME-180R cells. Alkaline elution studies of cross-linked DNA in CDDP-treated ME-180 cells suggested that accumulation of DNA adducts reached maximal levels 10-15 h after CDDP treatment and was similar in both TNF-resistant and parental cells. Within 24 h after CDDP exposure, the extent of DNA cross-linking was markedly reduced in parental cells but remained elevated in the CDDP-sensitive ME-180R cell line. To examine the proposed regulatory role of phosphorylation in CDDP and TNF-mediated cytotoxicity, epidermal growth factor (EGF) receptor tyrosine kinase activity was measured in both TNF-resistant and parental ME-180 cells. Analysis of cell lysates demonstrated a 3-4-fold higher EGF receptor tyrosine kinase activity in ME-180R cells when compared to the parental population which correlated with increased expression of EGF receptor protein by immunoblot analysis. Based upon colony-forming assays, EGF treatment of ME-180 parental cells resulted in an increased sensitivity to CDDP (similar to ME-180R cells) and 3-fold stimulation of EGF receptor tyrosine kinase activity. Taken together, these results suggest that TNF resistance in ME-180 cervical carcinoma cells correlates with both increased EGF receptor expression and enhanced CDDP cytotoxicity.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Resistance of human cervical carcinoma cells to tumor necrosis factor correlates with their increased sensitivity to cisplatin: evidence of a role for DNA repair and epidermal growth factor receptor. 138 Aug 90

Sialodacryoadenitis (SDA) is a commonly-encountered coronaviral infection in laboratory rats that causes acute destruction of submandibular salivary glands. SDA results in depletion of salivary epidermal growth factor (EGF) and may thereby affect EGF-dependent cell growth processes. The purpose of this study was to determine the effects of SDA virus (SDAV) infection on the growth factor-dependent stages of experimental liver carcinogenesis. Rats were injected ip with the carcinogen diethylnitrosamine (DENA) at 1, 2, or 3 weeks following inoculation with SDAV. Uninfected control rats were treated only with DENA. The salivary glands of SDAV-inoculated and control rats were stained using the immunoperoxidase method for the detection of EGF. Residual submandibular salivary gland lesions and focal depletion of EGF were still evident in affected submandibular glands for up to 42 days after SDAV infection. Serum EGF concentrations measured at 9, 28, and 42 days following SDAV inoculation were reduced, but were not significantly different in comparison with non-inoculated, DENA-treated control rats. Initiated hepatocytes were detected 21 days after DENA treatment in formalin-fixed sections by an immunoperoxidase stain for the P isoenzyme of the enzyme glutathione S-transferase (GST-P). There was no significant difference in the number of foci of GST-P positive cells in a comparison of initiated cells in SDAV-inoculated and non-inoculated rats. Based on this model, concurrent infection with SDAV does not appear to have any significant effects on the initial stages of chemical hepatocarcinogenesis in the rat.
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PMID:Lack of effects of viral sialoadenitis and depletion of epidermal growth factor on initiation of hepatic carcinogenesis in the rat. 166 70

We have described previously that in extracts of A431 cells epidermal growth factor (EGF) stimulates the phosphorylation of tyrosine as well as of threonine residues in the EGF receptor and in lipocortin 1. We now report that heparin at low concentrations also stimulates the autophosphorylation of the EGF receptor and of the recombinant 56-kDa domain of the EGF receptor that lacks the EGF binding site. To study the stimulations of phosphorylation of threonine residues, a fusion protein was prepared with glutathione S-transferase (GST) and an EGF receptor fragment, TK8 (residues 647-688), that contains the threonine phosphorylation site but no tyrosine. We show that the phosphorylation of threonine residues in GST-TK8 by extracts of A431 cells is stimulated by heparin but not by EGF. These and other results suggest that heparin acts as a chaperone, a substrate modulator, that enhances the susceptibility of the substrate to phosphorylation by protein kinases.
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PMID:Heparin stimulates epidermal growth factor receptor-mediated phosphorylation of tyrosine and threonine residues. 171 76

The effects of epidermal growth factor (EGF) (10 ng/ml) and insulin (100 nM) on the expression of glutathione S-transferases (GSTs), especially the GST-P form (GST 7-7), were examined in primary cultured rat hepatocytes in serum-free medium. On culture with EGF and insulin, the GST activities towards 1-chloro-2,4-dinitrobenzene and 1,2-dichloro-4-nitrobenzene were transiently decreased on day 2 to 10% of those of freshly isolated hepatocytes and then increased to 60 to 100% of those of freshly isolated cells on day 4. Western blot analysis of GSTs revealed that GST-P, which is not present in freshly isolated hepatocytes, was markedly induced and that GST subunits 3 and 4 of the Mu class also increased after addition of EGF and/or insulin, while the subunits 1 and 2 of the Alpha class disappeared. Northern blot analysis showed that on addition of EGF and insulin the level of GST-P mRNA was also elevated and expressions of the nuclear oncogenes c-jun and c-fos were enhanced. These results suggest that the enhanced expression of GST-P induced by EGF or insulin in primary cultured rat hepatocytes might be regulated by JUN and FOS proteins.
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PMID:Induction of glutathione S-transferase P-form in primary cultured rat hepatocytes by epidermal growth factor and insulin. 190 48

Hepatic transport of epidermal growth factor (EGF) was studied in D-galactosamine-intoxicated rats by the multiple-indicator dilution (MID) method. The extraction ratio of 125I-labeled EGF in the intoxicated rats, obtained from a model-independent analysis of the dilution curves, decreased to 45% of the control values. A distributed two-compartment model was fitted to the dilution data by nonlinear least-squares regression, and the kinetic parameters, kon.PT (product of on-rate constant and receptor density), koff (off-rate constant) and ks (sequestration rate constant) were determined. The values of kon.PT and ks in the intoxicated rats decreased to approximately one-half and one-third of those in the control rats respectively. Similar decreases in the kon.PT and ks values in the intoxicated rats were also observed for the transport of 125I-labeled insulin, a positive control, into the liver. The 125I-labeled EGF binding experiment at equilibrium using liver homogenates revealed that the intoxication reduced the receptor density (PT) to one-third of the control values, whereas the equilibrium dissociation constant (kd) did not change significantly. The activities of Na+,K+-ATPase, cytochrome P-450 and glutathione S-transferase decreased in the intoxicated rats to 70-80% of the control values. The number of nuclei per unit area of tissue slices was also reduced to 70% of the control. Thus, the extent to which the enzyme activities and the number of nuclei decreased in the intoxicated liver was smaller than that of the number of EGF receptors. It is concluded that the reduction of EGF receptors cannot be explained by the "intact hepatocyte hypothesis" but rather by the functional change of hepatocytes induced by the administration of D-galactosamine.
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PMID:Decrease in the number of receptors for epidermal growth factor in the liver of D-galactosamine-intoxicated rats. 266 65

We have reported previously that immunization with a bacterial recombinant protein containing the two epidermal growth factor (EGF)-like modules of Plasmodium yoelii Merozoite Surface Protein-1 (MSP-1) protected mice against challenge with this malaria parasite. Bacterial plasmids containing sequences coding for the individual modules fused to glutathione S-transferase (GST) have now been made. The fusion protein containing the combined EGF-like modules was recognized by anti-parasite antibodies and was immunogenic, producing high titre anti-parasite and anti-GST antibodies. In contrast, fusion proteins containing the two individual EGF-like modules reacted poorly with the natural antibodies and their proteins, as well as a simple mixture of them, induced low levels of anti-parasite antibodies despite producing high levels of anti-GST antibody. Antibodies raised to the recombinant proteins recognized the 230 kDa MSP-1. Groups of mice immunized with the different recombinant proteins were challenged with parasites: protection was observed in the group which had received the recombinant protein containing both modules but not in those groups immunized with the individual modules, either alone or as a mixture. These results suggest that there are important structural determinants formed by the two modules together, which are not present in either of the individual domains alone, and which are responsible for the immunogenicity of the protein or are the target of protective antibodies.
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PMID:The combined epidermal growth factor-like modules of Plasmodium yoelii Merozoite Surface Protein-1 are required for a protective immune response to the parasite. 750 23

The transforming gene of the avian sarcoma virus CT10 encodes a fusion protein (p47gag-crk or v-Crk) containing viral Gag sequences fused to cellular sequences consisting primarily of Src homology regions 2 and 3 (SH2 and SH3 sequences). Here we report a novel function of v-Crk in the mammalian pheochromocytoma cell line, PC12, whereby stable expression of v-Crk induces accelerated differentiation, as assessed by induction of neurites following nerve growth factor (NGF) or basic fibroblast growth factor (bFGF) treatment compared with the effect in native PC12 cells. Surprisingly, however, these cells also develop extensive neurite processes after epidermal growth factor (EGF) stimulation, an event which is not observed in native PC12 cells. Following EGF or NGF stimulation of the v-CrkPC12 cells, the v-Crk protein itself became tyrosine phosphorylated within 1 min. Moreover, in A431 cells or TrkA-PC12 cells, which overexpress EGF receptors and TrkA, respectively, a GST-CrkSH2 fusion protein was indeed capable of binding these receptors in a phosphotyrosine-dependent manner, suggesting that v-Crk can directly couple to receptor tyrosine kinase pathways in PC12 cells. In transformed fibroblasts, v-Crk binds to specific tyrosine-phosphorylated proteins of p130 and paxillin. Both of these proteins are also complexed to v-Crk in PC12 cells, as evidenced by their coprecipitation with v-Crk in detergent lysates, suggesting that common effector pathways may occur in both cell types. However, whereas PC12 cellular differentiation can occur solely by overexpression of the v-Src or oncogenic Ras proteins, that induced by v-Crk requires a growth factor stimulatory signal, possibility in a two-step process.
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PMID:Expression of the v-crk oncogene product in PC12 cells results in rapid differentiation by both nerve growth factor- and epidermal growth factor-dependent pathways. 750 49

The murine retroviral oncogene v-cbl induces pre-B cell lymphomas and myelogenous leukemias. The protein product of the mammalian c-cbl proto-oncogene is a widely expressed cytoplasmic 120-kDa protein (p120cbl) whose normal cellular function has not been determined. Here we show that upon stimulation of human epidermal growth factor (EGF) receptor, p12ocbl becomes strongly tyrosine-phosphorylated and associates with activated EGF receptor in vivo. A GST fusion protein containing amino acids 1-486 of p120cbl, including a region highly conserved in nematodes, binds directly to the autophosphorylated carboxyl-terminal tail of the EGF receptor. Platelet-derived growth factor (PDGF), fibroblast growth factor (FGF), or nerve growth factor (NGF) stimulation also results in tyrosine phosphorylation of p120cbl. Recent genetic studies in Caenorhabditis elegans indicate that Sli-1, a p120cbl homologue, plays a negative regulatory role in control of the Ras signaling pathway initiated by the C. elegans EGF receptor homologue. Our results indicate that p120cbl is involved in an early step in the EGF signaling pathway that is conserved from nematodes to mammals.
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PMID:Tyrosine phosphorylation of the c-cbl proto-oncogene protein product and association with epidermal growth factor (EGF) receptor upon EGF stimulation. 765 91

We report the isolation and molecular characterization of the mouse grb2 gene. The product of this gene, the Grb2 protein, is highly related to the Caenorhabditis elegans sem-5 gene product and the human GRB2 protein and displays the same SH3-SH2-SH3 structural motifs. In situ hybridization studies revealed that the mouse grb2 gene is widely expressed throughout embryonic development (E9.5 to P0). However, grb2 transcripts are not uniformly distributed, and in certain tissues (e.g., thymus) they appear to be regulated during development. Recent genetic and biochemical evidence has implicated the Grb2 protein in the signaling pathways that link cell surface tyrosine kinase receptors with Ras. We have investigated the association of the Grb2 protein with epidermal growth factor (EGF) and nerve growth factor (NGF) receptors in PC12 pheochromocytoma cells. EGF treatment of PC12 cells results in the rapid association of Grb2 with the activated EGF receptors, an interaction mediated by the Grb2 SH2 domain. However, Grb2 does not bind to NGF-activated Trk receptors. Mitogenic signaling of NGF in NIH 3T3 cells ectopically expressing Trk receptors also takes place without detectable association between Grb2 and Trk. These results suggest that whereas EGF and NGF can activate the Ras signaling pathway in PC12 cells, only the EGF receptor is likely to do so through a direct interaction with Grb2. Finally, binding studies with glutathione S-transferase fusion proteins indicate that Grb2 binds two distinct subsets of proteins which are individually recognized by its SH2 and SH3 domains. These observations add further support to the concept that Grb2 is a modular adaptor protein.
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PMID:Molecular cloning of the mouse grb2 gene: differential interaction of the Grb2 adaptor protein with epidermal growth factor and nerve growth factor receptors. 768 50


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