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

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Query: EC:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Data obtained from multiple sources indicate that no single mechanism can explain the resistance to chemotherapy exhibited by non-small cell lung carcinomas. The multi-factorial nature of drug resistance implies that the analysis of comprising expression profiles may predict drug resistance with higher accuracy than single gene or protein expression studies. Forty cellular parameters (drug resistance proteins, proliferative, apoptotic, and angiogenic factors, products of proto-oncogenes, and suppressor genes) were evaluated mainly by immunohistochemistry in specimens of primary non-small cell lung carcinoma of 94 patients and compared with the response of the tumours to doxorubicin in vitro. The protein expression profile of non-small cell lung carcinoma was determined by hierarchical cluster analysis and clustered image mapping. The cluster analysis revealed three different resistance profiles. The frequency of each profile was different (77, 14 and 9%, respectively). In the most frequent drug resistance profile, the resistance proteins P-glycoprotein/MDR1 (MDR1, ABCB1), thymidylate-synthetase, glutathione-S-transferase-pi, metallothionein, O6-methylguanine-DNA-methyltransferase and major vault protein/lung resistance-related protein were up-regulated. Microvessel density, the angiogenic factor vascular endothelial growth factor and its receptor FLT1, and ECGF1 as well were down-regulated. In addition, the proliferative factors proliferating cell nuclear antigen and cyclin A were reduced compared to the sensitive non-small cell lung carcinoma. In this resistance profile, FOS was up-regulated and NM23 down-regulated. In the second profile, only three resistance proteins were increased (glutathione-S-transferase-pi, O6-methylguanine-DNA-methyltransferase, major vault protein/lung resistance-related protein). The angiogenic factors were reduced. In the third profile, only five of the resistance factors were increased (MDR1, thymidylate-synthetase, glutathione-S-transferase-pi, O6-methylguanine-DNA-methyltransferase, major vault protein/lung resistance-related protein).
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PMID:Protein expression profiles indicative for drug resistance of non-small cell lung cancer. 1217 90

Double-stranded RNAs (dsRNAs) induce post-transcriptional gene silencing in several species of animal and plant. In plants, dsRNAs targeted to CpG islands within a promoter can also induce RNA-directed DNA methylation; however, it remains unclear whether gene silencing mediated by DNA methylation can be induced by dsRNAs in mammalian cells. Here, we demonstrate that short interfering RNAs (siRNAs; 21-25-nucleotide RNA molecules) induce DNA methylation and histone H3 methylation in human cells. Synthetic siRNAs targeted to CpG islands of an E-cadherin promoter induced significant DNA methylation and histone H3 lysine 9 methylation in both MCF-7 and normal mammary epithelial cells. As a result, these siRNAs repressed expression of the E-cadherin gene at the transcriptional level. In addition, disrupting the expression of either one of two DNA methyltransferases (DNMT1 or DNMT3B) by specific siRNAs abolished the siRNA-mediated methylation of DNA. Moreover, vector-based siRNAs targeted to the erbB2 (also known as HER2) promoter also induced DNA methylation in MCF-7 cells. Thus, siRNAs targeted to CpG islands within the promoter of a specific gene can induce transcriptional gene silencing by means of DNA-methyltransferase-dependent methylation of DNA in human cells, and might have potential as a new type of gene therapeutic agent.
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PMID:Induction of DNA methylation and gene silencing by short interfering RNAs in human cells. 1681 Feb 59

Malignant gliomas may manifest at any age including congenital and childhood cases. Peak incidence is, however, in adults older than 40 years. Males are more frequently affected than females. The sole unequivocal risk factor is therapeutic ionizing irradiation. Malignant gliomas comprise a spectrum of different tumor subtypes. Within this spectrum, glioblastoma, anaplastic astrocytoma and anaplastic oligodendroglioma share as basic features preferential location in cerebral hemispheres, diffuse infiltration of brain tissue, fast tumor growth with fatal outcome within months or years. Invasion is regarded as one of the main reasons for poor therapeutic success, because it makes complete surgical removal of gliomas impossible. Invasion of glioma cells requires interaction with the extracellular matrix and with surrounding cells of the healthy brain tissue. Vascular proliferates and tissue necrosis are characteristic features of malignant gliomas, in particular glioblastoma. These features are most likely the consequence of rapidly increasing tumor mass that is inadequately oxygenized by the preexisting vasculature. In malignant glioma, distinct molecular pathways including the p53 pathway, the RB pathway and the EGFR pathway show frequent alterations that seem to be pathogenetically relevant. Methylguanine-methyltransferase (MGMT) promoter methylation status in glioblastoma and 1p19q deletion status in anaplastic oligodendroglioma are associated with response to chemotherapy. The role of neuropathology and neurobiology in neurooncology is 1. to provide a clinically meaningful classification of brain tumors on basis of pathobiological factors, 2. to clarify etiology and pathogenesis of brain tumors as rational basis for development of new diagnostic tests and therapies, and 3. to translate testing for new clinically relevant molecular parameters into clinical application.
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PMID:Malignant glioma: neuropathology and neurobiology. 1694 63

The basal transcriptional activity of nuclear receptors (NRs) is regulated by interactions with additional comodulator proteins (coactivator/corepressor). Here, we describe a new androgen receptor (AR)-associated coactivator, PRMT2, which belongs to the arginine methyltransferase protein family. To search for AR-interacting proteins a fragment of the AR was used in a library screen exploiting the yeast two-hybrid technique and identifying the C-terminal region of PRMT2. We demonstrated that PRMT2 acts as a strong coactivator of the AR, had modest or none influence on transcriptional activation mediated by other NRs. Interestingly, PRMT2 interaction with the estrogen receptor (ER) was strongly dependent on the cellular background, thus, suggesting the involvement of additional, differentially expressed coregulators. We also demonstrated synergistic interaction of PRMT2 with other known nuclear receptor coactivators, such as GRIP1/TIF-2. Potentiation of AR-mediated transactivation by PRMT2 alone and in synergism with GRIP1 was prevented by a competitive inhibitor of methyltransferase activity. The PRMT2 expression profile overlaps with the distribution of AR, with strongest PRMT2 abundance in androgen target tissues. Immunofluorescence experiments showed that the intracellular localization of PRMT2 depends on the presence of the cognate receptor ligand. Under androgen-free conditions, both AR and PRMT2 are confined to the cytoplasm, whereas in the presence of androgens both proteins colocalize and translocate into the nucleus. Treatment with the AR antagonist hydroxyflutamide results in nuclear translocation of the AR, but not the coactivator PRMT2. Thus, it appears that the ligand-dependent AR conformation is essential for the recruitment and nuclear translocation of PMRT2 which acts as AR-coactivator, presumably by arginine methylation.
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PMID:PRMT2, a member of the protein arginine methyltransferase family, is a coactivator of the androgen receptor. 1758 66

Manganese superoxide dismutase (SOD2) is an enzyme that catalyses the dismutation of superoxide in the mitochondria, leading to reduced levels of reactive oxygen species. Reduced expression levels of SOD2 have been shown to result in increased DNA damage and sod2 heterozygous mice have increased incidences of cancer. It has also been shown that SOD2 expression is lost in pancreatic cell lines, with reintroduction of SOD2 resulting in decreased rate of proliferation. The mechanism of decreased SOD2 expression in pancreatic carcinoma has not been previously determined. We demonstrate, through sodium bisulphite sequencing, that the sod2 locus is methylated in some pancreatic cell lines leading to a corresponding decrease in SOD2 expression. Methylation can be reversed by treatment with zebularine, a methyltransferase inhibitor, resulting in restored SOD2 expression. Furthermore, we demonstrate that sensitivity of pancreatic carcinoma cell lines to 2-methoxyestradiol correlates with SOD2 expression and SOD2 modulation can alter the sensitivity of these cells. Using both genomics and proteomics, we also identify molecular consequences of SOD2 expression in MIA-PaCa2 cells, including dephosphorylation of VEGFR2 and the identification of both SOD2-regulated genes and transcription factors with altered binding activity in response to SOD2 expression.
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PMID:Molecular consequences of SOD2 expression in epigenetically silenced pancreatic carcinoma cell lines. 1789 90

Proteins are subject to various types of spontaneous modifications that can disrupt their structures with sometimes adverse affects on biological activity. The formation of L-isoaspartyl (or D-aspartyl) residues, through either the deamidation of asparagine or dehydration of aspartate, is one of the most frequent types of deterioration occurring under physiological conditions. Protein L-isoaspartate/D-aspartate o-methyltransferase (PIMT) is a conserved and ubiquitous enzyme that participates in the repair of various isomerized proteins. PIMT catalyzes the transfer of the methyl group of S-adenosyl-L-methionine onto the alpha-carboxyl group of an L-isoaspartyl (or the beta-carboxyl group of an D-aspartyl) residue, which initiates the conversion of this residue to an L-aspartyl residue. PIMT-deficient mice have been shown to die at a mean age of 42 days from progressive epileptic seizures with grand mal and myoclonus. Although PIMT-deficiency clearly leads to the accumulation of isomerized proteins, it is currently unclear how this causes progressive epilepsy in PIMT-deficient mice. As a first step towards understanding this, we developed a new assay to measure PIMT activity in cell lysates. Additionally, we isolated PIMT knockdown cells from HEK293 cells that were stably transfected with a PIMT small interfering RNA expression vector. PIMT activities were significantly decreased in the PIMT knockdown cells, and analysis of the transfectants revealed that MEK and ERK were hyperactivated after cell stimulation with epidermal growth factor (EGF). These results indicate that the ability to repair L-isoaspartyl-(or D-aspartyl-) containing proteins is important for the maintenance of normal MEK-ERK signaling.
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PMID:[Role of isomerized protein repair enzyme, PIMT, in cellular functions]. 1805 81

Pheochromocytomas are catecholamine-producing tumors of the adult adrenal medulla. They are rare in humans and most other species but common in laboratory rats. However, the relevance of rat pheochromocytomas as a model for their human counterparts is uncertain. Previous studies of spontaneous and drug-induced rat pheochromocytomas and the PC12 pheochromocytoma cell line suggested a distinctive noradrenergic phenotype, possibly reflecting origin from a progenitor not present in the adult human adrenal. In this study, we studied 31 pheochromocytomas derived from test and control male and female rats in toxicologic studies for expression of the epinephrine-synthesizing enzyme phenylethanolamine-N-methyltransferase (PNMT) and the receptor tyrosine kinase Ret. PNMT, which defines adrenergic chromaffin cells, is frequently expressed in human pheochromocytomas, often in tumors that also overexpress RET. We also tested for the expression of the cell cycle checkpoint protein p27(Kip1), which recently was reported absent in pheochromocytomas from a strain of rats with a hereditary mixed multiple endocrine neoplasia (MEN)-like syndrome. Using immunoblots, we demonstrated PNMT expression in almost 50% of the 31 tumors, although often at lower levels than in normal rat adrenal medulla. The majority of tumors overexpressed Ret. There was no apparent correlation between PNMT and Ret. However, in this study, PNMT expression was strongly associated with tumors arising in female rats, while overexpression of Ret did not show a sex predilection. Robust expression of p27(Kip1) was seen in all tumors from the toxicologic studies and also in a small sample of pheochromocytomas from Long-Evans rats, which were reported to have a mixed MEN-like syndrome in the 1980s. The present results show that rat pheochromocytomas have greater phenotypic diversity than previously believed and greater similarity to their human counterparts with respect to these two important markers. Loss of p27(Kip1) does not appear to account for the high frequency of pheochromocytomas in commonly utilized rat strains.
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PMID:Adrenergic differentiation and Ret expression in rat pheochromocytomas. 1831 52

l-Aspartyl (l-Asp) and l-asparaginyl residues in proteins isomerize or racemize to d,l-isoaspartyl (d,l-isoAsp) or d-aspartyl (d-Asp) residues during protein aging. These atypical aspartyl residues can interfere with the biological function of the protein and lead to cellular dysfunction. Protein l-isoaspartyl (d-aspartyl) methyltransferase (PIMT) is a repair enzyme that facilitates conversion of l-isoAsp and d-Asp to l-Asp. PIMT deficient mice exhibit accumulation of l-isoAsp in several tissues and die, on average, 12 days after birth from progressive epileptic seizures with grand mal and myoclonus features. However, little is known about the molecular mechanisms by which accumulation of the aberrant residues leads to cellular abnormalities. In this study, we established PIMT-knockdown cells using a short interfering RNA expression system and characterized the resultant molecular abnormalities in intracellular signaling pathways. PIMT-knockdown cells showed significant accumulation of proteins with isomerized residues, compared to control cells. In the PIMT-knockdown cells, Raf-1, MEK, and ERK, members of the MAPK cascade, were hyperphosphorylated after EGF stimulation compared to control cells. These results suggest that PIMT repair of abnormal proteins is necessary to maintain normal MAPK signaling.
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PMID:Suppression of protein l-isoaspartyl (d-aspartyl) methyltransferase results in hyperactivation of EGF-stimulated MEK-ERK signaling in cultured mammalian cells. 1838 Dec

Previous studies have shown two homologous chromodomain modules in the HP1 and Polycomb proteins exhibit discriminatory binding to related methyllysine residues (embedded in ARKS motifs) of the histone H3 tail. Methylated ARK(S/T) motifs have recently been identified in other chromatin factors (e.g. linker histone H1.4 and lysine methyltransferase G9a). These are thought to function as peripheral docking sites for the HP1 chromodomain. In vertebrates, HP1-like chromodomains are also present in the chromodomain Y chromosome (CDY) family of proteins adjacent to a putative catalytic motif. The human genome encodes three CDY family proteins, CDY, CDYL, and CDYL2. These have putative functions ranging from establishment of histone H4 acetylation during spermiogenesis to regulation of transcription co-repressor complexes. To delineate the biochemical functions of the CDY family chromodomains, we analyzed their specificity of methyllysine recognition. We detected substantial differences among these factors. The CDY chromodomain exhibits discriminatory binding to lysine-methylated ARK(S/T) motifs, whereas the CDYL2 chromodomain binds with comparable strength to multiple ARK(S/T) motifs. Interestingly, subtle amino acid changes in the CDYL chromodomain prohibit such binding interactions in vitro and in vivo. However, point mutations can rescue binding. In support of the in vitro binding properties of the chromodomains, the full-length CDY family proteins exhibit substantial variability in chromatin localization. Our studies underscore the significance of subtle sequence differences in a conserved signaling module for diverse epigenetic regulatory pathways.
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PMID:Specificity of the chromodomain Y chromosome family of chromodomains for lysine-methylated ARK(S/T) motifs. 1845 Jul 45

In oil palm (Elaeis guineensis Jacq.), approximately 5% of somatic embryo-derived regenerants show homeotic changes during floral development, involving an apparent feminization of male parts in flowers of both sexes, called the 'mantled' phenotype. This variant phenotype is associated with a reduction in the level of global DNA methylation. To explore possible relationships between DNA methylation level and accumulation of DNA-(cytosine-5) methyltransferase (DNMT) transcripts, the full-length coding sequences corresponding to three different DNMT families in oil palm, namely the MET, CMT, and DRM classes, have been isolated and characterized. The corresponding genes were designated as EgMET1, EgCMT1, and EgDRM1, and encode predicted polypeptides of 1543, 925, and 591 amino acid residues, respectively. Expression of oil palm DNMTs was compared between normal and variant calli and inflorescence tissues using quantitative reverse-transcription PCR. A consistent increase in transcript levels of EgMET1 and EgCMT1 was found in variant fast-growing calli relative to nodular-compact calli. Nodular-compact calli give rise to about 5% of abnormal regenerants whereas fast-growing calli generate 95% of 'mantled' palms in their clonal offspring and were previously demonstrated as having markedly hypomethylated DNA. In immature abnormal inflorescences only EgMET1 transcript levels were increased, while no changes in relative abundance of the EgCMT1 or EgDRM1 transcripts were observed. Therefore, the genome-wide hypomethylation previously described in 'mantled' material cannot be explained by a decrease in expression levels of the de novo or maintenance DNMTs, a paradox which has been previously reported in tumour cells, where there is evidence for global hypomethylation of DNA.
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PMID:Isolation and expression analysis of genes encoding MET, CMT, and DRM methyltransferases in oil palm (Elaeis guineensis Jacq.) in relation to the 'mantled' somaclonal variation. 1864 Sep 97


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