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)

Expression profiles were generated for the haemopoietic tyrosine kinase receptors (HGF-TKRs or class III TKRs) by PCR on cDNA samples (RT-PCR) using a degenerate primer set. Each profile consisted of primary and secondary, i.e. enriched for less-expressed sequences, fingerprints. This method was applied on FACS-purified haemopoietic CD34+ cells, both from bone marrow (BM) and umbilical cord blood (UCB), and on mature cells from peripheral blood. CD34+ BM cells showed expression of c-fms. flt3, whereas CD34+ UCB cells expressed c-fms and, to a lesser extent, c-kit and flt3. In mature blood cells, only c-fms was observed in monocytes and a weaker flt3 expression in monocytes and T lymphocytes, whereas no known class III TKRs were detected in B lymphocytes and polymorphonuclear cells (PMNs). In all fractions a novel band could be observed, which appeared to be RET. Expression of RET was confirmed by RT-PCR and showed the highest levels in monocytes, followed by PMNs and CD34+ cells. B lymphocytes revealed low levels of expression. RET is known to be essential in neural development. Our results suggest a possible role for this receptor in haemopoiesis.
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PMID:Haemopoietic growth factor tyrosine kinase receptor expression profiles in normal haemopoiesis. 875 81

Hepatocyte growth factor/scatter factor (HGF/SF) stimulates the invasive growth of epithelial cells via the c-MET oncogene-encoded receptor. In normal lung, both the receptor and the ligand are detected, and the latter is known to be a mitogenic and a motogenic factor for both cultured bronchial epithelial cells and non-small-cell carcinoma lines. Here, ligand and receptor expression was examined in 42 samples of primary human non-small-cell lung carcinoma of different histotype. Each carcinoma sample was compared with adjacent normal lung tissue. The Met/HGF receptor was found to be 2 to 10-fold increased in 25% of carcinoma samples (P = 0.0113). The ligand, HGF/SF, was found to be 10 to 100-fold overexpressed in carcinoma samples (P < 0.0001). Notably, while HGF/SF was occasionally detectable and found exclusively as a single-chain inactive precursor in normal tissues, it was constantly in the biologically-active heterodimeric form in carcinomas. Immunohistochemical staining showed homogeneous expression of both the receptor and the ligand in carcinoma samples, whereas staining was barely detectable in their normal counterparts. These data show that HGF/SF is overexpressed and consistently activated in non-small-cell lung carcinomas and may contribute to the invasive growth of lung cancer.
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PMID:Overexpression and activation of hepatocyte growth factor/scatter factor in human non-small-cell lung carcinomas. 898 Mar 83

The c-MET oncogene encodes the receptor for hepatocyte growth factor/scatter factor (HGF/SF), which is known to stimulate the invasive growth of epithelial cells cultured in vitro. The Met/HGF receptor is a heterodimeric transmembrane tyrosine kinase, which is a prototype for a new family of growth factor receptors. The c-MET oncogene is expressed in several types of epithelial tissue including keratinocytes and is over-expressed in a number of human carcinomas. Studies on various carcinoma cell lines have shown that over-expression and structural alteration of the receptor result in its activation and confer tumorigenesis. We have studied Met/HGF receptor expression in tissue specimens from 34 patients with head and neck squamous cell carcinomas (HNSCC) and in 17 regional lymph node metastases. Western blot analysis was employed, using monoclonal antibodies directed against either the intracellular or extracellular domain of the receptor. Each sample was compared to its normal counterpart. The receptor did not show any major structural alterations in HNSCC tissues, but its expression was increased from 2- to 50-fold in about 70% of tumors. Immunohistochemistry then showed that the same antibodies stained only a few cells in the basal layer of normal squamous epithelium but intensely marked tumor cells. In the lymph node metastases of Met-positive tumors, receptor expression was maintained and sometimes increased with respect to primary tumors. Immunohistochemical analysis of the metastatic lymph nodes showed that cells were negative in the normal lymphatic tissue and strongly stained in tumor cells. Over-expression of the Met/HGF receptor was found at all tumor stages but was more significant in those associated with enlarged or multiple (N2-N3) lymph node metastases. These data show that expression of the Met/HGF receptor may be involved in the progression of HNSCC towards a metastatic phenotype and may be a useful marker of head and neck tumor cell spread to regional lymph nodes.
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PMID:Detection of MET oncogene/hepatocyte growth factor receptor in lymph node metastases from head and neck squamous cell carcinomas. 906 49

Hepatocyte growth factor/scatter factor (HGF/SF) is a mesenchymally derived glycoprotein with a strong scattering effect on epithelial cells. A receptor tyrosine kinase encoded by the met proto-oncogene has been identified as the cellular receptor for HGF/SF. Following stimulation with HGF/SF, cell scattering occurs concurrent with decreased cell-cell adhesion and disassembly of junctional components. In culture, junction formation is cell-cell contact dependent and can be regulated by modulating the Ca2+ concentrations of the growth media. Decreasing the Ca2+ concentrations below 50 microM causes rapid disassembly of junctions, whereas increasing the Ca2+ concentrations to 1.8 mM induces cell-cell contact and junction assembly. Although associated with decreased cell-cell adhesion and disassembly of the junctional complex, HGF/SF-induced scattering occurs under high extracellular Ca2+ concentrations. To gain insight into the mechanisms of HGF/SF-induced scattering of epithelial cells, we have studied the effect(s) of HGF/SF on junction assembly by examining the solubility, stability, phosphorylation, and subcellular localization of the major components of the adhering junctions, plakoglobin (Pg) and E-cadherin, in Madin-Darby canine kidney (MDCK) epithelial cells and in a MDCK cell line expressing an exogenous chimeric met receptor (CSF-MET) that scatters in response to colony-stimulating factor 1 (CSF-1). The results have shown that in HGF/SF-stimulated MDCK cells, adhering junctions were not assembled upon induction of cell-cell contact. Immunofluorescence analyses showed that larger amounts of Pg and E-cadherin were Triton X-100 extractable, and more significantly, these proteins were homogeneously distributed along the membrane and were not concentrated at the areas of cell-cell contact. Similar results were obtained for CSF-MET expressing MDCK cells in response to CSF-1. In contrast, none of the above effects were detected in MDCK cells expressing a mutant CSF-MET chimera containing a phenylalanine substitution at tyrosine 1356 in met, which fails to scatter in response to CSF-1. When compared with the unstimulated cells, the inhibition of cell adhesion promoted by HGF/SF correlated with an increased stability of the newly synthesized soluble E-cadherin and Pg and an altered phosphorylation pattern of E-cadherin, as determined by partial proteolytic peptide mapping.
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PMID:Inhibition of junction assembly in cultured epithelial cells by hepatocyte growth factor/scatter factor is concomitant with increased stability and altered phosphorylation of the soluble junctional molecules. 910 Oct 91

Hepatocyte growth factor/scatter factor (HGF/SF) is secreted by mesenchymal cells and elicits proliferation, motility, differentiation, and morphogenesis of epithelia and other cells. These effects are mediated by binding to MET, a receptor tyrosine kinase. Genetically engineered mice lacking HGF/SF die in utero due to a failure of placental and hepatocyte differentiation, but little information exists regarding the expression of this signaling system in human development. Using reverse transcriptase-polymerase chain reaction, Western blots, and immunohistochemistry, we report that HGF/SF and MET are expressed during critical early periods of human organogenesis from 6 to 13 wk of gestation. Organs that expressed both genes included liver, metanephric kidney, intestine, and lung, each of which develop by inductive interactions between mesenchyme and epithelia. Of all organs studied, the placenta contained the highest levels of HGF/SF protein, and MET was detected in trophoblastic cells of chorionic villi as early as the 5th wk of gestation. Finally, examination of a human multicystic dysplastic kidney demonstrated that malformed, hyperproliferative tubules expressed MET, whereas HGF/SF protein was immunolocalized to the same epithelia and also to the surrounding undifferentiated cells. Hence HGF/SF might be an important growth factor in normal human embryogenesis and may additionally play a role in human organ malformations.
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PMID:Expression of hepatocyte growth factor/scatter factor and its receptor, MET, suggests roles in human embryonic organogenesis. 912 88

Morphology and immunohistochemical features of the developmental process of the human intrahepatic biliary system (IBS) are reviewed. Human IBS arises from the ductal plate, a double-layered cylindrical structure located at the interface between portal mesenchyme and primitive hepatocytes. The ductal plate first appears from primitive hepatocytes (hepatoblasts) around 8 gestational weeks (GW), and its formation proceeds from the hepatic hilum to the periphery. The ductal plate gradually undergoes remodeling from 12 GW; some parts of the ductal plate disappear and other parts migrate into the portal mesenchyme. Around 20 GW, the migrated duct cells transform into immature bile ducts and peribiliary glands. Some immature peribiliary glands transform into pancreatic acinar cells around postnatal 3 months. The immature biliary elements express cytokeratins no. 7, 8, 18 and 19. Several growth factors (TGF-alpha, HGF) and their receptors (EGFR, MET, ERBB2) were expressed in the primitive IBS cells. Some extracellular matrix proteins including type IV collagen, laminin and tenascin are expressed in the mesenchyme around the primitive IBS. During IBS remodeling, apoptosis and cell proliferation occur with appropriate expression of apoptosis-related proteins (bcl-2, Fas, c-myc, Lewis(y)). Some pancreatic digestive enzymes (alpha-amylase, trypsinogen, lipase), cathepsin B, and matrix metalloproteinases (MMP-1, 2, 3, 9) and their inhibitors (TIMP-1, 2) are expressed in the remodeling IBS cells. Glycoconjugate residues of glycoproteins gradually appear during IBS development. The appropriate expression of these immunophenotypes may play an important role in the normal development of IBS.
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PMID:Normal and abnormal development of the human intrahepatic biliary system: a review. 914 36

The hepatocyte growth factor/scatter factor (HGF/SF) receptor which is a transmembrane protein encoded by the Met oncogene, possesses intrinsic tyrosine kinase activity which transduces the mitogenic, morphogenic and the scattering effect of HGF/SF. The pluripotent signal of HGF/SF is transduced through association of the Met receptor with various intracellular adaptors. Phosphorylation of cytosolic phospholipase A2 (cPLA2) is associated with activation of this molecule which in turn leads to arachidonic acid production followed by release of prostaglandins and related compounds exerting their roles onto cell proliferation, chemotaxis and vascular motility. Arachidonic acid and its metabolites were shown to be involved in processes like liver regeneration where growth factor receptors possessing tyrosine kinase activity are implicated. In this study we examined whether stimulation of the HGF/SF-receptor's tyrosine kinase activity would involve changes in the phosphorylation state and the activity of cPLA2 in MDCK cells, where HGF/SF is known to induce scattering responses rather than mitogenesis. The activated p145betaMET was shown to associate with and to phosphorylate cPLA2 on tyrosine residues, this leading to subsequent release of arachidonic acid. cPLA2 was also phosphorylated in serine residues and such a role has been so far assigned to the mitogen activated protein (MAP) kinase. Our data have also shown that MAP kinase is associated and phosphorylated on tyrosine by the activated p145betaMET. Immunodepletion of MAP kinase via electroporation of an anti-MAP kinase antibody, did not significantly decrease arachidonic acid release in HGF/SF-stimulated MDCK cells. It is therefore emerging that phosphorylation of cPLA2 on tyrosine by the HGF/SF receptor kinase is capable of triggering arachidonic acid release and that MAP kinase is contributing to full, but does not drive, the activity of cPLA2. The release of arachidonic acid by MDCK cells following HGF/SF stimulation is establishing this fatty acid and its metabolites as major components involved in the transduction of MET-driven signals and at the same time in the amplification of such signals.
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PMID:Cytosolic phospholipase A2 is activated by the hepatocyte growth factor receptor-kinase in Madin Darby canine kidney cells. 924 99

Hepatocyte growth factor-scatter factor (HGF-SF ) mediates mito-, moto-, and morphogenic effects through the MET receptor, a membrane bound tyrosine kinase. HGF-SF/MET signaling is mitogenic for a large number of epithelial and endothelial cells and activates organ regeneration. HGF-SF transcripts have been detected in various myeloid cell lines. Therefore, the potential role of HGF-SF/MET signaling for circulating cells of the immune system, especially under conditions of inflammation, was evaluated. Several B-lymphoid and myeloid cell lines were found to express HGF-SF or c-met transcripts, while activity of both genes was mutually exclusive with the exception of low level coexpression in two B-cell lines. HGF-SF transcripts were present in low quantities in freshly isolated peripheral blood mononuclear cells (PBMNCs). In contrast, c-met expression was not detected in freshly isolated cells from peripheral blood, but was induced in monocytes by activation of monocytic or T-cell function. HGF-SF incubation led to an increased c-fos steady state transcript level in myeloblastic K562 cells and moderately promoted cell viability of freshly isolated preactivated monocytes. c-met expression is thus established in activated monocytes, in particular under conditions resembling inflammation, making these cells accessible to functional effects of HGF-SF.
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PMID:Neoexpression of the c-met/hepatocyte growth factor-scatter factor receptor gene in activated monocytes. 937 55

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

SMAD proteins mediate signals from receptor serine-threonine kinases (RSKs) of the TGF-beta superfamily. We demonstrate here that HGF and EGF, which signal through RTKs, can also mediate SMAD-dependent reporter gene activation and induce rapid phosphorylation of endogenous SMAD proteins by kinase(s) downstream of MEK1. HGF induces phosphorylation and nuclear translocation of epitope-tagged Smad2 and a mutation that blocks TGF-beta signaling also blocks HGF signal transduction. Smad2 may thus act as a common positive effector of TGF-beta- and HGF-induced signals and serve to modulate cross talk between RTK and RSK signaling pathways.
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PMID:Smad2 transduces common signals from receptor serine-threonine and tyrosine kinases. 962 Aug 46


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