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 on allelic polymorphism of MET and D7S23 DNA loci linked to the human cystic fibrosis gene studied in three Bashkir ethnic groups and some Volga-Ural populations (Tartars, Maris, Mordovians, Udmurts, Chuvashs, and Komis) are presented. Udmurts were found to be substantially different from Bashkirs, Tartars, Mordovians, and Chuvashs by the allele frequency distribution observed for MET, while Komis and Bashkirs differed by this parameter from Mordovians and Maris. Comparative analysis of restriction fragment length polymorphism (RFLP) at the D7S23 locus revealed statistically significant differences in genotype frequencies between Bashkirs of the Arkhangel' skii region and populations of Mordva and Udmurtia. In this respect, the Mordovian population appeared to be notably different from the populations of Bashkortostan, Tatarstan, Marii-El, Udmurtiya, Chuvashiya, and Komis. Genetic distances were calculated and corresponding dendrograms were constructed on the basis of data on Met-H, CS.7, and the ApoB locus hypervariable region allelic frequencies. Three ethnogeographic Bashkir groups belonging to one tree branch were found to be closely related to the populations of Tartars, Maris, Udmurts, and Chuvashs and substantially different from Komis and Mordovians. Thus, the position of Volga-Ural populations on the dendrogram corresponds to the degree of relationship between the Finno-Ugric and Turkic populations, confirming the usefulness of DNA polymorphism analysis for the study of the genetic structure of populations.
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PMID:[Allelic polymorphism of the DNA-loci met and D7S23, linked to the mucoviscidosis gene in human populations of the Volga-Ural region]. 944 22

Hepatocyte growth factor/scatter factor (HGF/SF) is a multifunctional factor that stimulates epithelial cell mitogenesis, motility, invasion, and morphogenesis. Its receptor is encoded by the MET proto-oncogene, a transmembrane receptor tyrosine kinase. Several studies have suggested a role for MET as a dominant oncogene in tumor development and progression. Conversely, MET is located at a region on chromosome 7q31 frequently deleted in carcinomas, suggesting that recessive mutations in MET may exist in certain cancers. To facilitate a search for mutations in MET, we have obtained the intron-exon structure of the human MET gene. We present the genomic structure of the first member of the Met receptor family to be characterized. Interestingly, MET contains a large second exon of 1214 nucleotides. We show that this exon, containing the AUG for the Met receptor, is frequently skipped in normal human tissues and cell lines, and corresponds to a ubiquitously expressed 7 kb Met transcript. This transcript yields no detectable protein product in vivo. Thus, unlike other genes, in which alternative splicing often gives rise to proteins with distinct activities, exon-skipping of MET exon 2 is predicted to decrease the abundance of a Met mRNA encoding a functional Met receptor.
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PMID:Intron-exon structure of the MET gene and cloning of an alternatively-spliced Met isoform reveals frequent exon-skipping of a single large internal exon. 948 74

Germline mutations in the RET proto-oncogene have been shown to be the underlying cause of multiple endocrine neoplasia type 2 (MEN 2A and 2B) and familial medullary thyroid carcinoma (FMTC). Some cases of sporadic medullary thyroid carcinoma (sporadic MTC) are reported to have specific codon 918, 883 and 768 mutations of the RET gene in tumor tissues. We examined RET gene mutations in 40 Japanese cases who had previously undergone surgery for sporadic MTC. DNA extracted from formalin-fixed tumor tissues and corresponding normal thyroid tissues or peripheral blood leukocytes was analyzed for mutations of exon 10, 11, 13, 14 and 16 of the RET gene by DNA sequencing and by mutation-specific restriction enzyme analysis. Germline RET point mutations were found in six of 40 cases (15%), cysteine residues at codon 618 in two, codon 634 in three and valine residue at codon 804 in one, and were newly identified as heritable MTC. Of the remaining 34 sporadic MTC cases, four (12%) had tumor-specific RET point mutations. Two were found in exon 16; one case showed an ATG to ACG (Met to Thr) mutation at codon 918, and the other showed two point mutations, ATG to ACG (Met to Thr) at codon 918 and GCA to GTA (Ala to Val) at codon 919 with loss of the wild-type allele, suggesting that both alleles at the RET locus were altered. The other two were found in exon 13; one case showed a CCG to TCG (Pro to Ser) mutation at codon 766 and the other showed a silent mutation, GTC to GTT (Val) at codon 778 with loss of the wild-type allele. There was no association of sporadic mutations with recurrence or prognosis in patients with sporadic MTC. The low rate of somatic RET mutation at codon 918 in our sporadic MTC suggests that as yet unknown factors may be involved. Genetic alterations in both alleles may have an important role in small fraction of sporadic MTCs.
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PMID:Novel point mutations and allele loss at the RET locus in sporadic medullary thyroid carcinomas. 961 47

Hepatocyte growth factor/scatter factor (HGF/SF) treatment of the Madin-Darby canine kidney epithelial cell line causes scattering of cells grown in monolayer culture and the formation of branching tubules by cells grown in collagen gels. HGF/SF causes prolonged activation of both the mitogen-activated protein (MAP) kinase extracellular signal-regulated kinase 2 (ERK2) and the phosphoinositide 3-OH kinase (PI 3-kinase) target protein kinase B (PKB)/Akt; inhibition of either the MAP kinase pathway by the MAP kinase/ERK kinase inhibitor PD98059 or the PI 3-kinase pathway by LY294002 blocks HGF/SF induction of scattering, although in morphologically distinct ways. Expression of constitutively activated PI 3-kinase, Ras, or R-Ras will cause scattering, but activated Raf will not, indicating that activation of the MAP kinase pathway is not sufficient for this response. Downstream of PI 3-kinase, activated PKB/Akt and Rac are both unable to induce scattering, implicating a novel pathway. Scattering induced by Ras or PI 3-kinase is sensitive to PD98059, as well as to LY294002, suggesting that basal MAP kinase activity is required, but not sufficient, for the scattering response. Induction of MDCK cell tubulogenesis in collagen gels by HGF/SF is inhibited by PD98059; expression of activated Ras and Raf causes disorganized growth in this system, but activated PI 3-kinase or R-Ras causes branching tubule formation similar to that seen with HGF/SF treatment. These data indicate that multiple signaling pathways acting downstream of Met and Ras are needed for these morphological effects; scattering is induced primarily by the PI 3-kinase pathway, which acts through effectors other than PKB/Akt or Rac and requires at least basal MAP kinase function. Elevated PI 3-kinase activity induces tubulogenesis, but total inhibition and excess activation of the MAP kinase pathway both oppose this effect.
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PMID:Phosphoinositide 3-kinase induces scattering and tubulogenesis in epithelial cells through a novel pathway. 966 53

ErbB3 (HER3), a unique member of the ErbB receptor family, lacks intrinsic protein tyrosine kinase activity and contains six Tyr-Xaa-Xaa-Met (YXXM) consensus binding sites for the SH2 domains of the p85 regulatory subunit of phosphoinositide 3-kinase. ErbB3 also has a proline-rich sequence that forms a consensus binding site for the SH3 domain of p85. Here we have investigated the interacting domains of ErbB3 and p85 by a unique application of the yeast two-hybrid system. A chimaeric ErbB3 molecule containing the epidermal growth factor receptor protein tyrosine kinase domain was developed so that the C-terminal domain of ErbB3 could become phosphorylated in the yeast system. We also generated several ErbB3 deletion and Tyr-->Phe site-specific mutants, and observed that a single ErbB3 YXXM motif was necessary and sufficient for the association of ErbB3 with p85. The incorporation of multiple YXXM motifs into the ErbB3 C-terminus enabled a stronger ErbB3/p85 interaction. The proline-rich region of ErbB3 was not necessary for interaction with p85. However, either deletion or mutation of the p85 SH3 domain decreased the observed ErbB3/p85 association. Additionally an ErbB3/p85 SH3 domain interaction was detected by an assay in vitro. These results were consistent with a model in which pairs of phosphorylated ErbB3 YXXM motifs co-operate in binding to the tandem SH2 domains of p85. Although a contributing role for the p85 SH3 domain was suggested, the N- and C-terminal SH2 domains seemed to be primarily responsible for the high-affinity association of p85 and ErbB3.
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PMID:ErbB3 (HER3) interaction with the p85 regulatory subunit of phosphoinositide 3-kinase. 967 38

We examined RET protooncogene mutations in sporadic medullary thyroid carcinoma (MTC), using polymerase chain reaction (PCR)-based sequencing. DNA was extracted from tumor tissue and peripheral blood leukocytes of seven unrelated individuals with apparently sporadic MTC. Oligonucleotide primers were selected to amplify exons 10, 11, 13, 15, and 16 of the RET protooncogene, to examine the sequences of codons 609, 611, 618, and 620 of exon 10, codon 634 of exon 11, codon 768 of exon 13, codon 883 of exon 15, and codon 918 of exon 16. Direct DNA sequencing from PCR products was then performed. The results showed that one patient had a somatic mutation at codon 918 (ATG-->ACG), causing a Met-->Thr substitution. One patient had a de novo germline mutation at codon 634 (TGC-->CGC), causing a Cys-->Arg substitution. Another patient had a germline mutation at codon 634 (TGC-->TTC), causing a Cys-->Phe substitution. In the remaining four cases, no RET mutations were found. Unexpectedly, two offspring of the patient (a female) with a germline mutation at codon 634 (TGC-->TTC) harbored homozygous alleles for the mutation; because the father did not carry this mutation, the other affected allele was suspected to have resulted from a de novo germline mutation of paternal origin. One of these offspring was subsequently diagnosed as having MTC. Our findings suggest that all patients with apparently sporadic MTC should be screened for the RET protooncogene by molecular analysis to detect occult or de novo multiple endocrine neoplasia 2 (MEN 2) or familial MTC. This would allow early treatment of affected family members.
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PMID:RET protooncogene mutations in patients with apparently sporadic medullary thyroid carcinoma. 974 64

Mutations in Met have been identified in human papillary renal carcinomas. We have shown previously that these mutations deregulate the enzymatic activity of Met and that NIH 3T3 cells expressing mutationally activated Met are transformed in vitro and are tumorigenic in vivo. In the present investigation, we find that mutant Met induces the motility of Madin-Darby canine kidney cells in vitro and experimental metastasis of NIH 3T3 cells in vivo, and that the Ras-Raf-MEK-ERK signaling pathway, which has been implicated previously in cellular motility and metastasis, is constitutively activated by the Met mutants. We also report that transgenic mice harboring mutationally activated Met develop metastatic mammary carcinoma. These data confirm the tumorigenic activity of mutant Met molecules and demonstrate their ability to induce the metastatic phenotype.
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PMID:The mutationally activated Met receptor mediates motility and metastasis. 982 15

It was recently reported that transgenic expression in the liver of truncated human Met renders hepatocytes constitutively resistant to apoptosis and reproducibly permits their immortalization. The derived stable cell lines (MMH from Met murine hepatocyte) are highly differentiated and nontransformed. In this report, the capacity of MMHs to support in vitro hematopoiesis is characterized. By reverse-transcription polymerase chain reaction, the expression by MMHs of cytokines involved in the survival and self-renewal of early progenitor cells (stem cell factor and FLT3 ligand) as well as those acting at different stages of progenitor differentiation (interleukin [IL] 1beta, IL-3, leukemia inhibitory factor, IL-6, granulocyte-macrophage colony-stimulating factor, granulocyte colony-stimulating factor, macrophage colony-stimulating factor, and thrombopoietin) was shown. A ribonuclease protection assay further substantiated the presence of at least six cytokine transcripts in MMH lines. Cocultures between MMH layers and progenitor-enriched fetal liver hematopoietic cells resulted in a 40-fold to 80-fold expansion of total hematopoietic cells and in a 2.5-fold expansion of clonogenic progenitors after 1 to 2 weeks. Hematopoiesis was maintained for up to 6 weeks with formation of typical cobblestone cell areas and continuous differentiation of precursor into cells at various degrees of maturation. At 5 weeks of coculture, clonogenic progenitors were maintained at 20% of the input level in coculture with embryonic-derived hepatocytes, showing the ability of hepatocyte feeder layer to support survival and possibly self-renewal of clonogenic progenitors. Therefore, the data emphasize a direct role of the hepatocyte in sustaining hematopoietic cell proliferation and differentiation.
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PMID:Hematopoietic support and cytokine expression of murine-stable hepatocyte cell lines (MMH). 982 30

Hepatocyte growth factor (HGF) and c-met proto-oncogene product (c-Met) have varied biological functions in different tissues and have been implicated in mitogenic, motogenic and morphogenic responses in both organ regeneration and carcinogenesis. Some studies have suggested that the overexpression of c-Met and epidermal growth factor receptor (EGFR) are associated with growth advantage, while transforming growth factor-beta receptor II (TGF beta R II) is associated with growth disadvantage of human prostatic adenocarcinoma. However, it is unclear if the expression of c-Met correlates with the expression of EGFR and TGF beta R II, and with the proliferative status of human prostatic adenocarcinoma. Using immunohistochemical staining with anti-c-Met (C-12), anti-EGFR (NCL-EGFR) and anti-TGF beta R II (L-21) antibodies, we determined the frequency of expression of c-MET, EGFR, and TGF beta R II respectively in a series of 134 radical prostatectomy specimens. We evaluated the relationship between the expression of these receptors and clinicopathological characteristics. Overall, c-Met immunostaining was detected in 54 of 134 (40.3%) cases, EGFR in 45 (33.6%) and TGF beta R II in 64 (48.4%). The overexpression of c-Met was significantly more common in poorly differentiated (P < 0.0001) and in the diffusely infiltrated specimens (P < 0.0005). In contrast, TGF beta R II was significantly overexpressed in the well differentiated specimens (P < 0.0001) and associated negatively with c-Met (P < 0.0001). Overall, these data suggest that c-Met/HGF receptor and TGF beta R II overexpression may be involved in the differentiation of human prostatic adenocarcinoma, c-Met with de-differentiation and TGF beta R II with differentiation.
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PMID:Overexpression of c-Met/hepatocyte growth factor receptors in human prostatic adenocarcinoma. 987 67

The mechanisms governing development of neural crest-derived melanocytes, and how alterations in these pathways lead to hypopigmentation disorders, are not completely understood. Hepatocyte growth factor/scatter factor (HGF/SF) signaling through the tyrosine-kinase receptor, MET, is capable of promoting the proliferation, increasing the motility, and maintaining high tyrosinase activity and melanin synthesis of melanocytes in vitro. In addition, transgenic mice that ubiquitously overexpress HGF/SF demonstrate hyperpigmentation in the skin and leptomenigenes and develop melanomas. To investigate whether HGF/ SF-MET signaling is involved in the development of neural crest-derived melanocytes, transgenic embryos, ubiquitously overexpressing HGF/SF, were analyzed. In HGF/SF transgenic embryos, the distribution of melanoblasts along the characteristic migratory pathway was not affected. However, additional ectopically localized melanoblasts were also observed in the dorsal root ganglia and neural tube, as early as 11.5 days post coitus (p.c.). We utilized an in vitro neural crest culture assay to further explore the role of HGF/SF-MET signaling in neural crest development. HGF/SF added to neural crest cultures increased melanoblast number, permitted differentiation into pigmented melanocytes, promoted melanoblast survival, and could replace mast-cell growth factor/Steel factor (MGF) in explant cultures. To examine whether HGF/SF-MET signaling is required for the proper development of melanocytes, embryos with a targeted Met null mutation (Met-/-) were analysed. In Met-/- embryos, melanoblast number and location were not overtly affected up to 14 days p.c. These results demonstrate that HGF/SF-MET signaling influences, but is not required for, the initial development of neural crest-derived melanocytes in vivo and in vitro.
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PMID:Hepatocyte growth factor/scatter factor-MET signaling in neural crest-derived melanocyte development. 1019 78


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