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)

Increased generation of active oxygen species such as H2O2 and O2- may be important in vascular smooth muscle cell growth associated with atherosclerosis and restenosis. In previous work, we showed that H2O2 stimulated vascular smooth muscle cell growth and proto-oncogene expression. In the present study, we compared the effects of H2O2 and O2- on cultured rat aortic vascular smooth muscle cell growth and signal transduction. O2- was generated in a concentration-dependent manner by the naphthoquinolinedione LY83583. Vascular smooth muscle cell growth, as measured by [3H]thymidine incorporation, was stimulated by 200 mumol/L H2O2 (110% increase versus 0.1% serum) and 1 mumol/L LY83583 (175% increase) to levels comparable to 10 ng/mL platelet-derived growth factor (210% increase). Since activation of mitogen-activated protein kinase (MAP kinase) is one of the earliest growth factor signal events, the activity of MAP kinase was measured by changes in mobility on Western blot and by phosphorylation of myelin basic protein. There was a concentration-dependent increase in MAP kinase activity by LY83583 (maximum, 10 mumol/L) but not by H2O2. The time course for activation of MAP kinase by LY83583 showed a maximum at 5 to 10 minutes with return to baseline by 20 minutes. Activation of MAP kinase by LY83583 was protein kinase C dependent. Expression of MAP kinase phosphatase-1 (MKP-1), a transcriptionally regulated redox-sensitive protein tyrosine/threonine phosphatase, was also measured. Although H2O2 induced MKP-1 mRNA to a greater extent than did LY83583, the increased MKP-1 expression could not explain the inability of H2O2 to stimulate MAP kinase, because mRNA levels were not detected until 60 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Differential activation of mitogen-activated protein kinases by H2O2 and O2- in vascular smooth muscle cells. 754 May 16

Previous studies from other laboratories suggest that linoleic acid and its metabolites, hydroperoxyoctadecadienoic acids, play an important role in modulating the growth of some cells. A correlation has been demonstrated between hydroperoxyoctadecadienoic acids and conditions characterized by abnormal cell growth such as atherosclerosis and psoriasis. To determine if linoleic acid and its metabolites modulate cell growth in atherosclerosis, we measured DNA synthesis, protooncogene mRNA expression, and mitogen-activated protein kinase (MAPK) activation in vascular smooth muscle cells (VSMC). Linoleic acid induces DNA synthesis, c-fos, c-jun, and c-myc mRNA expression and MAPK activation in VSMC. Furthermore, nordihydroguaiaretic acid, a potent inhibitor of the lipoxygenase system, significantly reduced the growth-response effects of linoleic acid in VSMC, suggesting that conversion of linoleic acid to hydroperoxyoctadecadienoic acids (HPODEs) is required for these effects. HPODEs also caused significant induction of DNA synthesis, protooncogene mRNA expression, and MAPK activation in growth-arrested VSMC, suggesting that linoleic acid and its metabolic products, HPODEs, are potential mitogens in VSMC, and that conditions such as oxidative stress and lipid peroxidation which provoke the production of these substances may alter VSMC growth.
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PMID:Linoleic acid and its metabolites, hydroperoxyoctadecadienoic acids, stimulate c-Fos, c-Jun, and c-Myc mRNA expression, mitogen-activated protein kinase activation, and growth in rat aortic smooth muscle cells. 763 78

Vascular endothelial cells, serving as a barrier between vessel and blood, are exposed to shear stress in the body. Although endothelial responses to shear stress are important in physiological adaption to the hemodynamic environments, they can also contribute to pathological conditions--e.g., in atherosclerosis and reperfusion injury. We have previously shown that shear stress mediates a biphasic response of monocyte chemotactic protein 1 (MCP-1) gene expression in vascular endothelial cells and that the regulation is at the transcriptional level. These observations led us to functionally analyze the 550-bp promoter region of the MCP-1-encoding gene to define the cis element responding to shear stress. The shear stress/luciferase assay on the deletion constructs revealed that a 38-bp segment (-53 to -90 bp relative to the transcription initiation site) containing two divergent phorbol ester "12-O-tetradecanoylphorbol 13-acetate" (TPA)-responsive elements (TRE) is critical for shear inducibility. Site-specific mutations on these two sites further demonstrated that the proximal one (TGACTCC) but not the distal one (TCACTCA) was shear-responsive. Shear inducibility was lost after the mutation or deletion of the proximal site. This molecular mechanism of shear inducibility of the MCP-1 gene was functional in both the epithelial-like HeLa cells and bovine aortic endothelial cells (BAEC). In a construct with four copies of the TRE consensus sequences TGACTACA followed by the rat prolactin minimal promoter and luciferase gene, shear stress induced the reporter activities by 35-fold and 7-fold in HeLa cells and BAEC, respectively. The application of shear stress on BAEC also induced a rapid and transient phosphorylation of mitogen-activated protein kinases. Pretreatment of BAEC with TPA attenuated the shear-induced mitogen-activated protein kinase phosphorylation, suggesting that shear stress and TPA share a similar signal transduction pathway in activating cells. The present study provides a molecular basis for the transient induction of MCP-1 gene by shear stress.
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PMID:The cis-acting phorbol ester "12-O-tetradecanoylphorbol 13-acetate"-responsive element is involved in shear stress-induced monocyte chemotactic protein 1 gene expression. 764 39

To elucidate the role of hyperinsulinemia in the development of atherosclerosis, we evaluated insulin-specific signaling in cultured vascular smooth muscle cells (SMCs) and its desensitization by continuous exposure to insulin. The concentration of unlabeled insulin that inhibited specific [A14-125I]-insulin binding by 50% (IC50) was 0.33 +/- 0.02 nM, which was 100 times less than the IC50 of unlabeled IGF-I. For [125I]-IGF-I binding, the IC50 of unlabeled IGF-I was found to be 6.6 +/- 0.88 nM, which was 100 times less than the IC50 of unlabeled insulin. The binding capacities for insulin and IGF-I were found to be 1.28 +/- 0.86 and 1200 +/- 170 fmol/0.5 mg protein, respectively. Autophosphorylation of the beta-subunit of the insulin receptor was stimulated at above 0.17 nM (24 microU/ml) insulin. Insulin concentrations exceeding 1 nM significantly activated the S6 kinase in a dose-dependent manner. In contrast, 10 nM insulin did not activate MAP kinase nor [3H]thymidine incorporation into DNA, while both were activated by 38% and 44% with 1 microM insulin and by 52% and 67% with 10 nM IGF-I, respectively. By pre-exposing cells to 10 nM insulin for 12 h, the binding capacity for insulin decreased by 34% (P < 0.05), and activation of S6 kinase by insulin almost disappeared, while both IGF-I binding and the activation of S6 kinase by IGF-I were not affected.(ABSTRACT TRUNCATED AT 250 WORDS)
Atherosclerosis 1995 Feb
PMID:Insulin-specific activation of S6 kinase and its desensitization in cultured rat vascular smooth muscle cells. 775 52

The vasoactive peptides endothelin-1 (ET-1) and angiotensin-II (AII) have been implicated in chronic hypertension and may play important roles in related vascular diseases such as restenosis and atherosclerosis. Using a rat aortic smooth muscle (RASM) cell model, both ET-1 and AII induced concentration-dependent delayed increases in DNA synthesis relative to that in the serum-deprived controls. Stimulation of DNA synthesis was maximal at 100 nM for each peptide. All treatment of RASM cells resulted in a greater mitogenic effect (4- to 7-fold) than that observed for ET-1 (3-fold). When added in the presence of AII, ET-1 had a supplemental effect on DNA synthesis (5- to 10-fold above control). Although RASM cells expressed both ETA and AT1 receptors, radioligand binding experiments indicated that approximately 10-fold as many AT1 receptors as ETA receptors were present. In signal transduction studies, ET-1 and AII each elicited concentration-dependent increases in the intracellular Ca2+ concentration. ET-1 and AII also stimulated phosphoinositide metabolism and phosphorylation of a specific substrate for protein kinase-C. The release of total inositol phosphates in response to ET-1 and AII was concentration dependent and inhibited by the ETA receptor-selective antagonist BQ-123 and the AT1 receptor-selective antagonist losartan, respectively. In addition, tyrosine phosphorylation of 120- and 75-kilodalton proteins as well as the mitogen-activated protein kinases p44mapk and p42mapk was observed within 5 min of the addition of either ET-1 or AII. Taken together, these data indicate that ET-1 and AII may promote smooth muscle cell growth through common intracellular signaling mechanisms.
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PMID:Endothelin-1 and angiotensin-II stimulate delayed mitogenesis in cultured rat aortic smooth muscle cells: evidence for common signaling mechanisms. 817 Apr 71

Serotonin (5-HT, 5-hydroxytryptamine) is a mitogen in vascular smooth muscle and vascular reactivity to 5-HT is significantly enhanced in hypertension and atherosclerosis. We have tested the hypothesis that tyrosine kinases, enzymes important for mitogenesis, may play a role in 5-HT-induced vascular smooth muscle contractility. Helical strips of rat carotid artery and aorta denuded of endothelium were mounted in tissue baths for measurement of contractile force. The tyrosine kinase inhibitor genistein (5 x 10(-6) M) decreased the potency of 5-HT approximately 4-fold and reduced maximal contraction to 5-HT in carotid arterial strips denuded of endothelium (58% control). Genistein's inactive congener daidzein (5 x 10(-6) M) did not reduce maximal contraction to 5-HT in carotid arteries but did shift the 5-HT concentration response curve 3-fold to the right. Tyrphostin 23 (5 x 10(-5) M), another tyrosine kinase inhibitor, decreased the potency of 5-HT 4-fold and reduced the maximal contraction to 5-HT in the carotid artery (10% control). Contractions induced by phorbol-12,13-dibutyrate (10(-9) to 10(-5) M) were not reduced or shifted by either tyrosine kinase inhibitor, indicating that phorbolester-sensitive protein kinase C isoforms were not affected. KCl-induced contraction was shifted 2-fold and the maximum significantly inhibited by tyrphostin 23 (38.6% control) but not genistein or daidzein, indicating that tyrphostin 23 but not genistein may inhibit voltage-gated calcium channels to reduce contractility. Western blot analysis using antiphosphotyrosine antibody confirmed that 5-HT produced a time- and concentration-dependent increase in the phosphotyrosine immunoreactivity of a 42-kD protein in cultured aortic smooth muscle cells. Lysate immunoprecipitation with an antimitogen-activated-protein (MAP)-kinase antibody indicated that the 42-kD protein was most likely a MAP kinase. 5-HT (10(-5) M) stimulated contraction and increased antiphosphotyrosine immunoreactivity in whole aorta mounted in tissue baths. Importantly, aortic contraction to 5-HT was shifted (5-fold rightward) and reduced (69% control) by genistein but not daidzein. These findings demonstrate that (1) tyrosine kinase activation may partially mediate contractility to 5-HT in arterial smooth muscle, (2) tyrphostin 23 is somewhat nonselective and (3) 5-HT stimulates tyrosine kinase as documented by increased tyrosyl phosphorylation of proteins in cultured aortic smooth muscle cells and aortic tissue in active contraction of 5-HT. These findings have significant implications not only in understanding a novel pathway of 5-HT signal transduction but also in vascular diseases in which growth and/or contractility to 5-HT is increased (e.g. hypertension, atherosclerosis).
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PMID:Serotonin stimulates protein tyrosyl phosphorylation and vascular contraction via tyrosine kinase. 869 53

To investigate the mechanisms for intracellular signaling and increased vascular tone by 8-epi-prostaglandin F2 alpha (8-epi-PGF2 alpha), we measured mitogen-activated protein kinase (MAPK) activity and myosin regulatory light chain (LC20) phosphorylation in porcine carotid arteries incubated with 8-epi-PGF2 alpha or PGF2 alpha. With stimulation by either 8-epi-PGF2 alpha or PGF2 alpha. MAPK activity and the force of contraction rose in parallel and were maintained during the time of exposure to agonist (2 hours). LC20 phosphorylation levels rose and then partially declined during stimulation with either agonist. The effects of 8-epi-PGF2 alpha on contraction, MAPK activity, and myosin light chain phosphorylation were completely inhibited by the receptor antagonists, SQ-29548 and BMS-180291; the effects of PGF2 alpha were only partially inhibited by these compounds. Thus, intracellular signaling by 8-epi-PGF2 alpha in fully differentiated vascular smooth muscle, resulting in MAPK activation and increased myosin phosphorylation, is specifically mediated by an activation of thromboxane A2/prostaglandin endoperoxide receptors. Lipid peroxidation and 8-epi-PGF2 alpha production, resulting from such vascular pathological processes as atherosclerosis, lead to an activation of two intracellular signaling pathways in smooth muscle: one pathway results in the activation of MAPK, while the other results in myosin light chain phosphorylation.
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PMID:Intracellular signaling by 8-epi-prostaglandin F2 alpha is mediated by thromboxane A2/prostaglandin endoperoxide receptors in porcine carotid arteries. 878 Jul 11

Vascular smooth muscle cell (VSMC) proliferation and migration are responses to arterial injury that are highly important to the processes of restenosis and atherosclerosis. In the arterial balloon injury model in the rat, platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF) are induced in the vessel wall and regulate these VSMC activities. Novel insulin sensitizing agents, thiazolidinediones, have been demonstrated to inhibit insulin and epidermal growth factor-induced growth of VSMCs. We hypothesized that these agents might also inhibit the effect of PDGF and bFGF on cultured VSMCs and intimal hyperplasia in vivo. Troglitazone (1 microM), a member of the thiazolidinedione class, produced a near complete inhibition of both bFGF-induced DNA synthesis as measured by bromodeoxyuridine incorporation (6.5+/-3.9 vs. 17.6+/-4.3% cells labeled, P < 0.05) and c-fos induction. This effect was associated with an inhibition (by 73+/-4%, P < 0.01) by troglitazone of the transactivation of the serum response element, which regulates c-fos expression. Inhibition of c-fos induction by troglitazone appeared to occur via a blockade of the MAP kinase pathway at a point downstream of MAP kinase activation by MAP kinase kinase. At this dose, troglitazone also inhibited PDGF-BB-directed migration of VSMC (by 70+/-6%, P < 0.01). These in vitro effects were operative in vivo. Quantitative image analysis revealed that troglitazone-treated rats had 62% (P < 0.001) less neointima/media area ratio 14 d after balloon injury of the aorta compared with injured rats that received no troglitazone. These results suggest troglitazone is a potent inhibitor of VSMC proliferation and migration and, thus, may be a useful agent to prevent restenosis and possibly atherosclerosis.
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PMID:Troglitazone inhibits vascular smooth muscle cell growth and intimal hyperplasia. 887 42

Hemodynamic forces play a key role in inducing atherosclerosis-implicated gene expression in vascular endothelial cells. To elucidate the signal transduction pathway leading to such gene expression, we studied the effects of fluid shearing on the activities of upstream signaling molecules. Fluid shearing (shear stress, 12 dynes/cm2 [1 dyne = 10(-5)N]) induced a transient and rapid activation of p21ras and preferentially activated c-Jun NH2 terminal kinases (JNK1 and JNK2) over extracellular signal-regulated kinases (ERK-1 and ERK-2). Cotransfection of RasN17, a dominant negative mutant of Ha-Ras, attenuated the shear-activated JNK and luciferase reporters driven by 12-O-tetradecanoylphorbol-13-acetate-responsive elements. JNK(K-R) and MEKK(K-M), the respective catalytically inactive mutants of JNK1 and MEKK, also partially inhibited the shear-induced luciferase reporters. In contrast, Raf301, ERK(K71R), and ERK(K52R), the dominant negative mutants of Raf-1, ERK-1, and ERK-2, respectively, had little effect on the activities of these reporters. The activation of JNK was also correlated with increased c-Jun transcriptional activity, which was attenuated by a negative mutant of Son of sevenless. Thus, mechanical stimulation exerted by fluid shearing activates primarily the Ras-MEKK-JNK pathway in inducing endothelial gene expression.
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PMID:The Ras-JNK pathway is involved in shear-induced gene expression. 888 24

Hyperinsulinemia has been recognized as an independent risk factor for atherosclerosis. However, its exact mechanisms are still unclear. In our previous work, we showed that 10 nmol/L insulin stimulated neither mitogen-activated protein kinase (MAP kinase) activity nor [3H]thymidine incorporation but did stimulated S6 kinase through the specific insulin receptors in cultured rat vascular smooth muscle cells (VSMCs). In this study, we observed that > or = 1 nmol/L insulin stimulated tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1) and activated IRS-1-dependent phosphatidylinositol 3'-kinase (PI 3'-kinase) and p70 S6 kinase (p70S6K) but not MAP kinase (extracellular signal-regulated kinase 2) and p90 S6 kinase (p90RSK). However, 10 nmol/L insulin-like growth factor I stimulated all these pathways. Finally, 10 nmol/L insulin stimulated alpha-amino-isobutyric acid (AIB) uptake, and wortmannin (100 nmol/L) completely inhibited insulin-stimulated AIB uptake, whereas rapamycin (20 nmol/L) had no such effect. Furthermore, cycloheximide (10 micrograms/mL) completely inhibited insulin-stimulated AIB uptake, but actinomycin D (5 micrograms/mL) failed to inhibit this. Thus, we reached the following conclusions: (1) Insulin (1 nmol/L) induced phosphorylation of IRS-1 and activated the PI 3'-kinase and p70S6K pathways in VSMCs, even though 10 nmol/L insulin did not significantly stimulate MAP kinase or p90RSK. (2) Stimulation of AIB uptake by insulin was regulated at the translational level via wortmannin-sensitive pathways but not p70S6K pathways.
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PMID:Insulin signaling and its regulation of system A amino acid uptake in cultured rat vascular smooth muscle cells. 894 55


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