Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.24 (mitogen-activated protein kinase)
 95,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the present study we describe the intracellular pathways for the transmission of growth signals by the potent vasoconstricting eicosanoids prostaglandin H2 and thromboxane A2 in smooth muscle cells from rat aorta. Carbocyclic thromboxane A2 and U46619 are stable thromboxane A2 mimetics acting at the common thromboxane A2/prostaglandin H2 receptor. Carbocyclic thromboxane A2 (10(-6) mol/L) induced an approximately 2.5-fold increase in [Ca2+]i above the basal value at 25 seconds. Maximal stimulation of the 42-kD mitogen-activated protein kinase isoform by both thromboxane A2 mimetics occurred at 5 minutes. Both thromboxane A2 mimetics at a concentration of 10(-6) mol/L induced the expression of c-fos and early growth response gene-1 (egr-1) mRNA, with a maximum at 30 minutes. Carbocyclic thromboxane A2 (10(-6) mol/L) induced a 3.3-fold increase in [3H]thymidine incorporation into cell DNA above the basal value and produced a 3.5-fold elevation of platelet-derived growth factor-BB-dependent [3H]thymidine incorporation into cell DNA. Similar effects of U46619 (10(-6) to 10(-5) mol/L) alone did in combination with platelet-derived growth factor-BB on cell DNA synthesis were obtained. The thromboxane A2/prostaglandin H2 receptor antagonist SQ29548 (10(-6) mol/L) completely suppressed the mitogenic effect of both thromboxane A2 mimetics (10(-6) mol/L). Pertussis toxin (10 to 100 ng/mL) did not influence the mitogenic effects of the thromboxane A2 mimetics. Carbocyclic thromboxane A2 (10(-6) mol/L) and platelet-derived growth factor-BB (20 ng/mL) per ser caused a 44% and 100% increase in cell number, respectively. In the presence of carbocyclic thromboxane A2 (10(-6) mol/L), platelet-derived growth factor-BB induced a 152% increase in cell number. Similar results were obtained with U46619 alone or in combination with platelet-derived growth factor-BB.
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PMID:Thromboxane A2 and vascular smooth muscle cell proliferation. 759 Oct 17

In cultured rat aortic smooth muscle cells, angiotensin II (AII) treatment led to increased tyrosine phosphorylation of cellular proteins with apparent molecular masses of 42, 44, 75, and 120 kDa, respectively, as assessed by antiphosphotyrosine immunoblotting. Increased protein tyrosine phosphorylation was observed within 1 min of AII addition and was maximal by 30 min. The overall pattern of AII-stimulated protein tyrosine phosphorylation was distinct from that observed following treatment of rat aortic smooth muscle cells with platelet-derived growth factor-BB. Specific antibodies were used to identify the AII-stimulated 42- and 44-kDa tyrosine-phosphorylated proteins as the "mitogen-activated protein kinases," p42mapk and p44mapk, respectively. Raf-1, a 70-74-kDa serine/threonine protein kinase, was not tyrosine-phosphorylated in response to AII but was found to be hyperphosphorylated as evidenced by retarded protein mobility in SDS gel analysis. Taken together, these data indicate that AII binding to vascular smooth muscle cells leads to rapid activation of a complex cascade of protein kinases, including protein kinase C, Raf-1, MAP kinases, and an undefined intracellular protein tyrosine kinase(s) that may be coordinately involved in signal transduction leading to cell proliferation.
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PMID:Angiotensin II stimulation of rapid protein tyrosine phosphorylation and protein kinase activation in rat aortic smooth muscle cells. 838 3

1. In cultures of bovine tracheal smooth muscle cells, platelet-derived growth factor-BB (PDGF), bradykinin (BK) and endothelin-1 (ET-1) stimulated the tyrosine phosphorylation and activation of both pp42 and pp44 kDa forms of mitogen-activated protein (MAP) kinase. 2. Both ET-1 and PDGF stimulated a sustained activation of MAP kinase whilst the response to BK was transient. 3. Activation of MAP kinase occurred in a concentration-dependent manner (EC50 values: ET-1, 2.3 +/- 1.3 nM; BK, 8.7 +/- 4.1 nM, PDGF, 9.7 +/- 3.2 ng ml-1). 4. Pretreatment with the protein kinase C (PKC) inhibitor Ro-318220, significantly reduced ET-1 activation of MAP kinase at 2 and 5 min but enhanced MAP kinase activation at 60 min. 5. Following chronic phorbol ester pretreatment, BK-stimulated activation of MAP kinase was abolished whilst the responses to PDGF and ET-1 were only partly reduced (80 and 45% inhibition respectively). 6. Pretreatment with pertussis toxin reduced ET-1 stimulated activation of MAP kinase particularly at later times (60 min), but left the responses to both PDGF and BK unaffected. 7. ET-1 also stimulated a 3 fold increase in [3H]-thymidine incorporation which was abolished by pertussis toxin pretreatment. In contrast, PDGF stimulated a 131 fold increase in [3H]-thymidine incorporation which was not affected by pertussis toxin. 8. These results suggest that a pertussis toxin-sensitive activation of MAP kinase may play an important role in ET-1-stimulated DNA synthesis but that activation of MAP kinase alone is not sufficient to induce the magnitude of DNA synthesis observed in response to PDGF.
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PMID:Stimulation by endothelin-1 of mitogen-activated protein kinases and DNA synthesis in bovine tracheal smooth muscle cells. 856 58

The mechanisms responsible for altered vascular smooth muscle cell (VSMC) function in hypertension remain unknown. In the spontaneously hypertensive rat (SHR) model of genetic hypertension, there are multiple abnormalities in VSMC function, including increased growth, Na(+)-H+ exchange, and increased signal transduction by protein kinase C. The family of kinases termed mitogen-activated protein (MAP) kinases has recently been shown to be essential mediators of growth factor signal transduction. In the present study, alterations in MAP kinase function in the hypertensive phenotype were investigated using early-passage SHR and Wistar-Kyoto (WKY) VSMCs stimulated with angiotensin II (Ang II, 100 nmol/L) or platelet-derived growth factor-BB (PDGF-BB, 10 ng/mL). MAP kinase activity was measured by in-gel kinase assays and Western blot analysis. Two differences between SHR and WKY rats were observed for Ang II-mediated MAP kinase activation: (1) Inactivation after Ang II stimulation was more rapid in SHR than WKY VSMCs. (2) Activity in SHR VSMCs showed a greater dependence on Ca2+ mobilization, since chelation of intracellular Ca2+ with BAPTA inhibited maximal activity by 95% in SHR VSMCs but by only 50% in WKY VSMCs. In contrast to the results with Ang II, no differences in PDGF-stimulated MAP kinase activity were observed. These findings establish activation of MAP kinase by Ang II as a feature that distinguishes SHR VSMCs from WKY VSMCs and suggest that differences in regulation of MAP kinase signaling may alter cellular events that are increased in the SHR genetic model of hypertension.
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PMID:Ca(2+)-dependent mitogen-activated protein kinase activation in spontaneously hypertensive rat vascular smooth muscle defines a hypertensive signal transduction phenotype. 863 46

This study investigates thromboxane A2-induced cell signaling and mitogenesis of bovine coronary artery smooth muscle cells. The thromboxane mimetic U 46619 [(15S)-hydroxy-11,9-(epoxymethano) prosta-5Z,13E-dienoic acid] (10 microM) stimulated [Ca2+]i signals, phosphorylation of MAP kinase (mitogen-activated protein kinase), and expression of c-fos mRNA in smooth muscle cells. In contrast, no stimulation of DNA synthesis or cell proliferation by U 46619 was observed. However, platelet-derived growth factor-BB (20 ng/ml)-induced mitogenesis was potentiated by U 46619. Similar results were obtained with I-BOP [1S-(1 alpha,2 beta(5Z),3 alpha(1E,3R*), 4 alpha)]-7-[3-(3-hydroxy-4-(4'-iodophenoxy)-1-butenyl)-7-oxabicyclo [2.2.1] heptan-2-yl]-5-heptenoic acid]. These potentiating effects were abrogated by a specific thromboxane receptor antagonist, suggesting that the potentiation of platelet-derived growth factor-BB-induced smooth muscle cell mitogenesis by U 46619 and I-BOP was mediated by thromboxane receptors. It is concluded that thromboxane A2 generated by blood platelets at the site of vessel injury induces cell signaling in smooth muscle cells but acts as a mitogen only in the presence of growth factor(s).
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PMID:Thromboxane A2 induces cell signaling but requires platelet-derived growth factor to act as a mitogen. 904 8

We recently demonstrated that basic fibroblast growth factor (FGF-2) and platelet-derived growth factor-BB (PDGF-BB) mainly activated extracellular signal-regulated kinase 2 (ERK2) in normal human osteoblastic (HOB) and bone marrow stromal (HBMS) cells by an "in-gel" MAP kinase assay, although both ERK1 and ERK2 proteins were present. In the present study, we examined whether ERK1 is also activated by growth factors by using three different MAPK assay procedures, an "in-gel MAP kinase assay," an immune-complex kinase assay, and western blotting with anti-active MAPK antibody which recognizes specifically activated forms of both ERK1 and ERK2. Results have demonstrated that in addition to ERK2, ERK1 is activated by FGF-2 and PDGF-BB in normal HOB and HBMS cells. The human ERK1 moved faster on SDS-polyacrylamide gel compared to rat and mouse, revealing differences in the apparent molecular weight of FRK1 in normal human osteoblastic and bone marrow osteoprogenitor cells, human (TE-85) and rat (ROS 17/2.8 and UMR-106) osteosarcoma, and mouse (MC3T3E1) osteoblastic cells. ERK1 is less stable in the in-gel renaturation process compared to ERK2; thus, in-gel MAP kinase assay does not provide an accurate estimation of ERK1 activity. Results also showed that anti-active MAPK antibody can be used reliably and accurately to measure the activation of ERK1 and ERK2 in osteoblastic cells.
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PMID:Activation of extracellular signal-regulated kinases 1 and 2 (ERK1 and ERK2) by FGF-2 and PDGF-BB in normal human osteoblastic and bone marrow stromal cells: differences in mobility and in-gel renaturation of ERK1 in human, rat, and mouse osteoblastic cells. 929 66

Directed cell migration is essential for a variety of important biological processes ranging from development and angiogenesis to metastasis. Ras plays a pivotal role in the signaling cascade that governs chemotaxis of fibroblasts toward platelet-derived growth factor-BB (PDGF-BB). Ras activates multiple downstream pathways, which include the extracellular signal-regulated kinase (ERK), Rac, and Ral signaling cascades. We therefore investigated the role of the Rac and ERK pathways in cell migration. We showed that migration of fibroblasts toward PDGF-BB is inhibited by expression of dominant negative Asn-17 Rac1. Blocking of the ERK pathway by either expression of dominant negative Ala-218/Ala-222-mitogen-activated protein kinase kinase (A218/A222-MEK1) or by a MEK-specific inhibitor did not inhibit migration toward PDGF-BB. In contrast, migration toward soluble fibronectin was suppressed by inhibition of the ERK pathway but not by Asn-17 Rac1 expression. These results indicate that directed cell migration mediated by different receptor classes in response to different ligands differentially utilizes the Rac and ERK pathways and suggest that Rac might play a critical role in pathological processes such as angiogenesis and metastasis.
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PMID:Platelet-derived growth factor and fibronectin-stimulated migration are differentially regulated by the Rac and extracellular signal-regulated kinase pathways. 938 4

The urokinase-type plasminogen activator (UPA) and its receptor are expressed in the vasculature and are involved in cell migration and remodeling of the extracellular matrix in the neointima. Vessels with atherosclerosis or neointimal hyperplasia, when compared with normal vessels, contain high UPA activity as well as increased levels of UPA receptor. In this study, we have identified the stimulation of vascular smooth muscle cell proliferation as a novel activity for UPA in the vessel wall. High-molecular-weight-UPA (12-200 nmol/L range) stimulated DNA synthesis and cell proliferation, which was half that induced by fetal calf serum or by platelet-derived growth factor-BB. UPA did not induce growth of endothelial cells, and tissue-type plasminogen activator showed no activity on either cell type. Induction of proliferation required the complete UPA molecule but was independent of the proteolytic activity of UPA, whereas neither the amino-terminal fragment nor the catalytic domain by itself was mitogenic. UPA also stimulated c-fos/c-myc mRNA expression and mitogen-activated protein kinase activity in smooth muscle cells. Blocking monoclonal antibodies against the UPA receptor and the enzymatic removal of receptors were ineffective in inhibiting the mitogenic effect of UPA, suggesting a UPA receptor-independent mechanism. Thus, we provide evidence for a novel function of UPA on vascular smooth muscle cell proliferation that, together with its previously documented involvement in regulating pericellular proteolysis-related events and cell migration, provides additional evidence for a role in the pathogenesis of atherosclerosis/restenosis.
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PMID:Induction of vascular SMC proliferation by urokinase indicates a novel mechanism of action in vasoproliferative disorders. 940 65

We have recently reported that angiotensin II (Ang II)-induced mitogen-activated protein kinase (MAPK) activation is mainly mediated by Ca2+-dependent activation of a protein tyrosine kinase through Gq-coupled Ang II type 1 receptor in cultured rat vascular smooth muscle cells (VSMC). In the present study, we found Ang II rapidly induced the tyrosine phosphorylation of the epidermal growth factor (EGF) receptor and its association with Shc and Grb2. These reactions were inhibited by the EGF receptor kinase inhibitor, AG1478. The Ang II-induced phosphorylation of the EGF receptor was mimicked by a Ca2+ ionophore and completely inhibited by an intracellular Ca2+ chelator. Thus, AG1478 abolished the MAPK activation induced by Ang II, a Ca2+ ionophore as well as EGF but not by a phorbol ester or platelet-derived growth factor-BB in the VSMC. Moreover, Ang II induced association of EGF receptor with catalytically active c-Src. This reaction was not affected by AG1478. These data indicate that Ang II induces Ca2+-dependent transactivation of the EGF receptor which serves as a scaffold for pre-activated c-Src and for downstream adaptors, leading to MAPK activation in VSMC.
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PMID:Calcium-dependent epidermal growth factor receptor transactivation mediates the angiotensin II-induced mitogen-activated protein kinase activation in vascular smooth muscle cells. 953 70

Through direct synthetic efforts, we discovered a small molecule that is a nanomolar inhibitor of the human fibroblast growth factor-1 receptor (FGFR) tyrosine kinase. PD 166866, a member of a new structural class of tyrosine kinase inhibitors, the 6-aryl-pyrido[2,3-d]pyrimidines, was identified by screening a compound library with assays that measure protein tyrosine kinase activity. PD 166866 inhibited human full-length FGFR-1 tyrosine kinase with an IC50 value of 52.4 +/- 0.1 nM and was further characterized as an ATP competitive inhibitor of the FGFR-1. In contrast, PD 166866 had no effect on c-Src, platelet-derived growth factor receptor-beta, epidermal growth factor receptor or insulin receptor tyrosine kinases or on mitogen-activated protein kinase, protein kinase C and CDK4 at concentrations as high as 50 microM. PD 166866 was a potent inhibitor of basic fibroblast growth factor (bFGF)-mediated receptor autophosphorylation in NIH 3T3 cells expressing endogenous FGFR-1 and in L6 cells overexpressing the human FGFR-1 tyrosine kinase, confirming a tyrosine kinase-mediated mechanism. PD 166866 also inhibited bFGF-induced tyrosine phosphorylation of the 44- and 42-kDa (ERK 1/2) mitogen-activated protein kinase isoforms in L6 cells, presumably via inhibition of bFGF-stimulated FGFR-1 tyrosine kinase activation. PD 166866 did not inhibit platelet-derived growth factor, epidermal growth factor or insulin-stimulated receptor autophosphorylation in vascular smooth muscle, A431 or NIHIR cells, respectively, further supporting its specificity for the FGFR-1. In addition, daily exposure of PD 166866 to L6 cells at concentrations from 1 to 100 nM resulted in a concentration-related inhibition of bFGF-stimulated cell growth for 8 consecutive days with an IC50 value of 24 nM. In contrast, PD 166866 had little effect on platelet-derived growth factor-BB-stimulated growth of L6 cells or serum-stimulated vascular smooth muscle cell proliferation. Finally, PD 166866 was found to be a potent inhibitor of microvessel outgrowth (angiogenesis) from cultured artery fragments of human placenta. These results highlight the discovery of PD 166866, a new nanomolar potent and selective small molecule inhibitor of the FGFR-1 tyrosine kinase with potential use as antiproliferative/antiangiogenic agent for such therapeutic targets as tumor growth and neovascularization of atherosclerotic plaques.
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PMID:In vitro biological characterization and antiangiogenic effects of PD 166866, a selective inhibitor of the FGF-1 receptor tyrosine kinase. 965 4


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