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

Recently, we demonstrated that pulsatile mechanical stretch induced rapid secretion of vascular endothelial growth factor (VEGF) by cultured rat cardiac myocytes in vitro. To investigate whether pulsatile stretch activates intracellular signaling in cardiac myocytes, we examined the activation of mitogen-activated protein kinase (MAPK) family members and focal adhesion kinase (p125(FAK)) in cultured rat cardiac myocytes. We found that pulsatile stretch rapidly phosphorylated p44/p42 MAPKs (extracellular signal-regulated protein kinase [ERK] 1/2), stress-activated protein kinase (SAPK), p38MAPK, and p125(FAK). The stretch-induced activation of ERKs was at least partly mediated by VEGF, which was shown to be induced by transforming growth factor (TGF)-beta, and was also partly dependent on tyrosine kinases as well as protein kinase C (PKC). These data provide the direct evidence that pulsatile stretch can activate intracellular signaling in cardiac myocytes and that this was at least partly mediated by VEGF, which may play a role in cardiac adaptation to mechanical overload.
 ...
PMID:Pulsatile stretch activates mitogen-activated protein kinase (MAPK) family members and focal adhesion kinase (p125(FAK)) in cultured rat cardiac myocytes. 1033 7

Vascular endothelial growth factor (VEGF) has been proposed to be among the candidate factors with the most potential to play a role in ischemia-induced collateral vessel formation. Recently, we found that VEGF activated the mitogen-activated protein kinase cascade in cultured rat cardiac myocytes. To elucidate how VEGF affects adhesive interaction of cardiac myocytes with the extracellular matrix (ECM), one of the important cell functions, we investigated the molecular mechanism of activation of focal adhesion-related proteins, especially focal adhesion kinase (p125(FAK)), in cultured rat cardiac myocytes. We found that the 2 VEGF receptors, KDR/Flk-1 and Flt-1, were expressed in cardiac myocytes and that KDR/Flk-1 was significantly tyrosine phosphorylated on VEGF stimulation. VEGF induced tyrosine phosphorylation and activation of p125(FAK) as well as tyrosine phosphorylation of paxillin; this was accompanied by subcellular translocation of p125(FAK) from perinuclear sites to the focal adhesions. This VEGF-induced activation of p125(FAK) was inhibited partially by the tyrosine kinase inhibitors genistein and tyrphostin. Activation of p125(FAK) was accompanied by its increased association with adapter proteins GRB2, Shc, and nonreceptor type tyrosine kinase p60(c-src). Furthermore, we confirmed that VEGF induced a significant increase in adhesive interaction between cardiac myocytes and ECM using an electric cell-substrate impedance sensor. These results strongly suggest that p125(FAK) is one of the most important components in VEGF-induced signaling in cardiac myocytes, playing a critical role in adhesive interaction between cardiac myocytes and ECM.
 ...
PMID:Vascular endothelial growth factor induces activation and subcellular translocation of focal adhesion kinase (p125FAK) in cultured rat cardiac myocytes. 1034 94

Reactive oxygen species (ROS) are implicated in the pathophysiology of several vascular disorders including atherosclerosis. Although the mechanism(s) of ROS-induced vascular damage remains unclear, there is increasing evidence for ROS-mediated modulation of signal transduction pathways. Exposure of bovine pulmonary artery endothelial cells to hydrogen peroxide (H(2)O(2)) enhanced tyrosine phosphorylation of 60- to 80- and 110- to 130-kDa cellular proteins, which were determined by immunoprecipitation with specific antibodies focal adhesion kinase (p125(FAK)) and paxillin (p68). Brief exposure of cells to a relatively high concentration of H(2)O(2) (1 mM) resulted in a time- and dose-dependent tyrosine phosphorylation of FAK, which reached maximum levels within 10 min (290% of basal levels). Cytoskeletal reorganization as evidenced by the appearance of actin stress fibers preceded H(2)O(2)-induced tyrosine phosphorylation of FAK, and the microfilament disruptor cytochalasin D also attenuated the tyrosine phosphorylation of FAK. Treatment of BPAECs with 1,2-bis(2-aminophenoxy)ethane-N,N,N', N'-tetraacetic acid-AM attenuated H(2)O(2)-induced increases in intracellular Ca(2+) but did not show any consistent effect on H(2)O(2)-induced tyrosine phosphorylation of FAK. Several tyrosine kinase inhibitors, including genistein, herbimycin, and tyrphostin, had no detectable effect on tyrosine phosphorylation of FAK but attenuated the H(2)O(2)-induction of mitogen-activated protein kinase activity. We conclude that H(2)O(2)-induced increases in FAK tyrosine phosphorylation may be important in H(2)O(2)-mediated endothelial cell activation.
 ...
PMID:Hydrogen peroxide stimulates tyrosine phosphorylation of focal adhesion kinase in vascular endothelial cells. 1040 42

Vascular smooth muscle cell (VSMC) proliferation is a prominent feature of the atherosclerotic process occurring after endothelial injury. A vascular wall kallikrein-kinin system has been described. The contribution of this system to vascular disease is undefined. In the present study we characterized the signal transduction pathway leading to mitogen-activated protein kinase (MAPK) activation in response to bradykinin (BK) in VSMC. Addition of 10(-10)-10(-7) M BK to VSMC resulted in a rapid and concentration-dependent increase in tyrosine phosphorylation of several 144- to 40-kDa proteins. This effect of BK was abolished by the B(2)-kinin receptor antagonist HOE-140, but not by the B(1)-kinin receptor antagonist des-Arg(9)-Leu(8)-BK. Immunoprecipitation with anti-phosphotyrosine antibodies followed by immunoblot revealed that 10(-9) M BK induced tyrosine phosphorylation of focal adhesion kinase (p125(FAK)). BK (10(-8) M) promoted the association of p60(src) with the adapter protein growth factor receptor binding protein-2 and also induced a significant increase in MAPK activity. Pertussis and cholera toxins did not inhibit BK-induced MAPK tyrosine phosphorylation. Protein kinase C downregulation by phorbol 12-myristate 13-acetate and/or inhibitors to protein kinase C, p60(src) kinase, and MAPK kinase inhibited BK-induced MAPK tyrosine phosphorylation. These findings provide evidence that activation of the B(2)-kinin receptor in VSMC leads to generation of multiple second messengers that converge to activate MAPK. The activation of this crucial kinase by BK provides a strong rationale to investigate the mitogenic actions of BK on VSMC proliferation in disease states of vascular injury.
 ...
PMID:Mechanisms of MAPK activation by bradykinin in vascular smooth muscle cells. 1044 1

Because integrin-mediated signals are transferred through a physical architecture and synergistic biochemical network whose properties are not well defined, quantitative relationships between extracellular integrin-ligand binding events and key intracellular responses are poorly understood. We begin to address this by quantifying integrin-mediated FAK and ERK2 responses in CHO cells for varied alpha(5)beta(1) expression level and substratum fibronectin density. Plating cells on fibronectin-coated surfaces initiated a transient, biphasic ERK2 response, the magnitude and kinetics of which depended on integrin-ligand binding properties. Whereas ERK2 activity initially increased with a rate proportional to integrin-ligand bond number for low fibronectin density, the desensitization rate was independent of integrin and fibronectin amount but proportional to the ERK2 activity level with an exponential decay constant of 0.3 (+/- 0.08) min(-1). Unlike the ERK2 activation time course, FAK phosphorylation followed a superficially disparate time course. However, analysis of the early kinetics of the two signals revealed them to be correlated. The initial rates of FAK and ERK2 signal generation exhibited similar dependence on fibronectin surface density, with both rates monotonically increasing with fibronectin amount until saturating at high fibronectin density. Because of this similar initial rate dependence on integrin-ligand bond formation, the disparity in their time courses is attributed to differences in feedback regulation of these signals. Whereas FAK phosphorylation increased to a steady-state level as new integrin-ligand bond formation continued during cell spreading, ERK2 activity was decoupled from the integrin-ligand stimulus and decayed back to a basal level. Accordingly, we propose different functional metrics for representing these two disparate dynamic signals: the steady-state tyrosine phosphorylation level for FAK and the integral of the pulse response for ERK2. These measures of FAK and ERK2 activity were found to correlate with short term cell-substratum adhesivity, indicating that signaling via FAK and ERK2 is proportional to the number of integrin-fibronectin bonds.
 ...
PMID:Quantitative relationship among integrin-ligand binding, adhesion, and signaling via focal adhesion kinase and extracellular signal-regulated kinase 2. 1048 Sep 27

The dramatic increase in uterine growth during late pregnancy and the generation of labor contractions require dynamic remodeling of myometrial smooth muscle-ECM interactions. In many tissues, such interactions are provided by focal adhesions; however, there are no data as to the expression of focal adhesion proteins or of focal adhesion signaling in the myometrium. In this study, we show that tyrosine phosphorylation of myometrial FAK (FAK-P-Tyr) and of its downstream substrate, paxillin, exhibited a >10-fold increase during late pregnancy (days 15-22 of pregnancy) with each exhibiting a dramatic fall in P-Tyr on day 23 in association with the onset of labor. These changes in FAK-P-Tyr were paralleled by changes in FAK enzyme activity. Activated ERK1 and ERK2 expression remained relatively unchanged from day 15 to day 23, but decreased markedly 1 day post partum. Treatment of late pregnant rats with progesterone prevented the fall in FAK-P-Tyr/enzyme activity on day 23, and also blocked the onset of labor. These data suggest that progesterone (which decreases at term) modulates myometrial FAK activity/focal adhesion signaling and that these changes may underlie the tremendous remodeling that must occur in order for this muscle to develop optimal contractile activity during labor.
 ...
PMID:Focal adhesion signaling in the rat myometrium is abruptly terminated with the onset of labor. 1061 48

beta1-integrins play crucial roles in a variety of cell processes such as adhesion, migration, proliferation, and differentiation of lymphocytes. For understanding the molecular mechanisms of these various biological effects, it may be particularly important to analyze cell signaling through the beta1-integrins. Our previous study had shown that PLC-gamma, pp125FAK (focal adhesion kinase), pp105, paxillin, p59fyn, p56lck and ERK1/2 are phosphorylated in their tyrosine residues upon engagement of beta1-integrins. We identified pp105 as Cas (Crk-associated substrate)-related protein and successfully cloned its cDNA. pp105 is a Cas homologue predominantly expressed in the cells of lymphoid lineage, which led us to designate it as Cas-L. Like p130Cas, Cas-L contains a single SH3 domain and multiple SH2 binding sites (YXXP motif), which is suggested to bind SH2 domains of Crk, Nck, and SHPTP2. Subsequent studies revealed that pp125FAK binds Cas-L on its SH3 domain and phosphorylates its tyrosine residues upon beta1-integrin stimulation. Since Cas-L is preferentially expressed in lymphocytes, it is conceivable that Cas-L plays an important role in lymphocyte-specific signals. We have shown that Cas-L is involved in the T-cell receptor (TCR)/CD3 signaling pathway as well as the beta1-integrin signaling pathway. Cas-L is transiently phosphorylated following CD3 cross-linking, and tyrosine-phosphorylated Cas-L binds to Crk and C3G. Furthermore, a Cas-L mutant (Cas-LDeltaSH3), which lacks the binding site for FAK, is still tyrosine-phosphorylated upon CD3 cross-linking, but not upon beta1-integrin cross-linking, suggesting that FAK is not involved in CD3-dependent Cas-L phosphorylation. Finally, we have identified a crucial role of Cas-L in beta1-integrin-mediated T-cell co-stimulation. beta1-integrins have known to provide a co-stimulus for TCR/CD3-driven interleukin-2 production and proliferation of peripheral T-cells. We have found that this co-stimulatory pathway is impaired in the Jurkat T-cell line, and that the expression level of Cas-L is reduced in Jurkat cells compared with peripheral T-cells. The transfection of Cas-L cDNA into Jurkat cells restored the beta1-integrin-mediated co-stimulation, while the transfection of Cas-LDeltaSH3 mutant failed to do so, showing a contrast to the case with CD3-mediated signaling. These results indicate that Cas-L plays a key role through the association and phosphorylation by FAK in the beta1-integrin-mediated T-cell co-stimulation. Taken together, Cas-L might be the bi-modal docking protein that assembles the signals through beta1-integrins and TCR/CD3, and participates in a variety of T-cell functions.
 ...
PMID:Beta 1-integrin-mediated cell signaling in T lymphocytes. 1080 24

To explore how heparan sulfate (HS) controls the responsiveness of the breast cancer cell lines MCF-7 and MDA-MB-231 to fibroblast growth factors (FGFs), we have exposed them to HS preparations known to have specificity for FGF-1 (HS glycosaminoglycan (HSGAG A)) or FGF-2 (HSGAGB). Proliferation assays confirmed that MCF-7 cells were highly responsive to FGF-2 complexed with GAGB, whereas migration assays indicated that FGF-1/HSGAGA combinations were stimulatory for the highly invasive MDA-MB-231 cells. Quantitative polymerase chain reaction for the levels of FGF receptor (FGFR) isoforms revealed that MCF-7 cells have greater levels of FGFR1 and that MDA-MB-231 cells have greater relative levels of FGFR2. Cross-linking demonstrated that FGF-2/HSGAGB primarily activated FGFR1, which in turn up-regulated the activity of mitogen-activated protein kinase; in contrast, FGF-1/HSGAGA led to the phosphorylation of equal proportions of both FGFR1 and FGFR2, which in turn led to the up-regulation of Src and p125(FAK). MDA-MB-231 cells were particularly responsive to vitronectin substrates in the presence of FGF-1/HSGAGA, and blocking antibodies established that they used the alpha(v)beta(3) integrin to bind to it. These results suggest that the clustering of particular FGFR configurations on breast cancer cells induced by different HS chains leads to distinct phenotypic behaviors.
 ...
PMID:The proliferative and migratory activities of breast cancer cells can be differentially regulated by heparan sulfates. 1086 17

The second messenger cyclic AMP regulates diverse biological processes such as cell morphology and cell growth. We examined the role of the second messenger cyclic AMP on rat aortic vascular smooth muscle cell (VSMC) morphology and the intracellular transduction pathway mediated by platelet-derived growth factor beta-receptor (PDGF-Rbeta). The effect of PDGF-BB on VSMCs growth was assessed by [(3)H]-thymidine incorporation. Tyrosine phosphorylation of PDGF-Rbeta, PLC-gamma1, ERK1 and ERK2, p125(FAK) and paxillin as well as Sm alpha-actin was examined by the chemiluminescence Western blotting method. Actin mRNA level was quantitated by Northern blotting. Visualization of Sm alpha-actin filaments, paxillin and PDGF-Rbeta was performed by immunfluorescence microscopy. Cholera toxin (CTX; 10 nM) treatment lead to a large and sustained increase in the cyclic AMP concentration after 2 h which correlated with change of VSMC morphology including complete disruption of the Sm alpha-actin filament array and loss of focal adhesions. Treatment of VSMCs with CTX did not influence tyrosine phosphorylation of p125(FAK) and paxillin but decreased the content of a Sm alpha-actin protein. Maximal decrease of 70% was observed after 24 h of treatment. CTX also caused a 90% decrease of the actin mRNA level. CTX treatment completely abolished PDGF-BB stimulated DNA-synthesis although PDGF-Rbeta level and subcellular distribution and translocation was not altered. Furthermore CTX attenuated the PDGF-BB-induced tyrosine phosphorylation of the PDGF-Rbeta, PI 3'-K, PLC-gamma1 and ERK1/2 indicating an action of cyclic AMP on PDGF-beta receptor. We conclude that although cyclic AMP attenuates the PDGF-Rbeta mediated intracellular transduction pathway, an intact actin filament may be required for the PDGF-BB-induced DNA synthesis in VSMCs.
 ...
PMID:Cholera toxin treatment of vascular smooth muscle cells decreases smooth muscle alpha-actin content and abolishes the platelet-derived growth factor-BB-stimulated DNA synthesis. 1092 58

We have previously identified FAK and its associated signaling pathways as a mediator of cell cycle progression by integrins. In this report, we have analyzed the potential role and mechanism of Pyk2, a tyrosine kinase closely related to FAK, in cell cycle regulation by using tetracycline-regulated expression system as well as chimeric molecules. We have found that induction of Pyk2 inhibited G(1) to S phase transition whereas comparable induction of FAK expression accelerated it. Furthermore, expression of a chimeric protein containing Pyk2 N-terminal and kinase domain and FAK C-terminal domain (PFhy1) increased cell cycle progression as FAK. Conversely, the complementary chimeric molecule containing FAK N-terminal and kinase domain and Pyk2 C-terminal domain (FPhy2) inhibited cell cycle progression to an even greater extent than Pyk2. Biochemical analyses indicated that Pyk2 and FPhy2 stimulated JNK activation whereas FAK or PFhy1 had little effect on it, suggesting that differential activation of JNK by Pyk2 may contribute to its inhibition of cell cycle progression. In addition, Pyk2 and FPhy2 to a greater extent also inhibited Erk activation in cell adhesion whereas FAK and PFhy1 stimulated it, suggesting a role for Erk activation in mediating differential regulation of cell cycle by Pyk2 and FAK. A role for Erk and JNK pathways in mediating the cell cycle regulation by FAK and Pyk2 was also confirmed by using chemical inhibitors for these pathways. Finally, we showed that while FAK and PFhy1 were present in focal contacts, Pyk2 and FPhy2 were localized in the cytoplasm. Interestingly, both Pyk2 and FPhy2 (to a greater extent) were tyrosine phosphorylated and associated with Src and Fyn. This suggested that they may inhibit Erk activation in an analogous manner as the mislocalized FAK mutant (&Dgr;)C14 described previously by competing with endogenous FAK for binding signaling molecules such as Src and Fyn. This model is further supported by an inhibition of endogenous FAK association with active Src by Pyk2 and FPhy2 and a partial rescue by FAK of Pyk2-mediated cell cycle inhibition.
 ...
PMID:Pyk2 and FAK differentially regulate progression of the cell cycle. 1093 44


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>