Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.4.3 (phospholipase C)
 18,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Group 1 metabotropic glutamate receptors (mGluR1 and mGluR5) stimulate phospholipase C (PLC) and lead to mobilization of intracellular Ca(2+) and activation of protein kinase C (PKC). In this investigation, using heterologous receptor-expressing Chinese hamster ovary (CHO) cells, we showed that stimulation of mGluR1 or mGluR5 with glutamate rapidly increases tyrosine phosphorylation of focal adhesion kinase (FAK) (maximum at 1-3 min) in a dose-dependent manner (half-maximal responses at approximately 2 microM). In mGluR1-expressing cells, the glutamate-induced increase of FAK tyrosine phosphorylation was blocked by not only the PLC inhibitor, U73122, but also depletion of intracellular Ca(2+) and effectively abrogated by calmodulin (CaM) inhibitors, calmidazolium and fluphenazine. However, neither the PKC inhibitor, GF109203X, nor the CaM kinase II inhibitor, KN-62, inhibited glutamate-stimulated FAK tyrosine phosphorylation. Stimulation of mGluR1 caused a marked increase in actin stress fiber formation. Importantly, this actin rearrangement was prevented by the CaM inhibitor, but not by the PKC inhibitor and is thus in a good agreement with the signaling cascade of the mGluR1-FAK pathway. These results suggest that the Ca(2+)/CaM signaling and its downstream FAK tyrosine phosphorylation play an important role in cellular function of mGluR1.
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PMID:Glutamate induces focal adhesion kinase tyrosine phosphorylation and actin rearrangement in heterologous mGluR1-expressing CHO cells via calcium/calmodulin signaling. 1146 72

The increase in intracellular Ca(2+) and myosin light chain (MLC) phosphorylation in response to the contractile activation of tracheal smooth muscle is greater at longer muscle lengths (21). However, MLC phosphorylation can also be stimulated by Ca(2+)-insensitive signaling pathways (19). The cytoskeletal proteins paxillin and focal adhesion kinase (FAK) mediate a Ca(2+)-independent length-sensitive signaling pathway in tracheal smooth muscle (30). We used alpha-toxin-permeabilized tracheal smooth muscle strips to determine whether the length sensitivity of MLC phosphorylation can be regulated by a Ca(2+)-insensitive signaling pathway and whether the length sensitivity of active tension depends on the length sensitivity of myosin activation. Although active tension remained length sensitive, ACh-induced MLC phosphorylation was the same at optimal muscle length (L(o)) and 0.5 L(o) when intracellular Ca(2+) was maintained at pCa 7. MLC phosphorylation was also the same at L(o) and 0.5 L(o) in strips stimulated with 10 microM Ca(2+). In contrast, the Ca(2+)-insensitive tyrosine phosphorylation of FAK and paxillin stimulated by ACh was higher at L(o) than at 0.5 L(o). We conclude that the length-sensitivity of MLC phosphorylation depends on length-dependent changes in intracellular Ca(2+) but that length-dependent changes in MLC phosphorylation are not the primary mechanism for the length sensitivity of active tension.
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PMID:Selected contribution: roles of focal adhesion kinase and paxillin in the mechanosensitive regulation of myosin phosphorylation in smooth muscle. 1150 48

Pasteurella multocida toxin (PMT) is an unusual toxin that acts as a mitogen by stimulating various intracellular signalling cascades. Pathways downstream of the G-protein Gq and also downstream of the Rho proteins are activated. Thus PMT action stimulates phospholipase C leading to activation of protein kinase C, an increase in inositol phosphates, and a rise in intracellular calcium. Rho activation of the Rho kinase leads to cytoskeletal reorganisation, tyrosine phosphorylation of the focal adhesion kinase, and activation of the Src proto-oncogene. In addition, signalling through the Ras-MAP kinase signalling pathway is also initiated. PMT is an intracellularly acting toxin, and functional domains that carry out different aspects of its function have been described. The intracellular target of the toxin is currently not known. PMT also acts to inhibit differentiation, in particular of bone cells, where it prevents the formation of mineralised bone nodules in vitro. The toxin is the causative agent of a porcine disease that is characterised by bone resorption. Injection of very low doses of toxin leads to proliferative effects, but at higher doses is lethal. The possible effect of PMT-induced perturbation of signal transduction pathways is discussed.
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PMID:Pasteurella multocida toxin: the mitogenic toxin that stimulates signalling cascades to regulate growth and differentiation. 1168 Jul 86

Angiogenesis is an essential step for many physiological and pathological processes. Tumor necrosis factor (TNF) superfamily cytokines are increasingly recognized as key modulators of angiogenesis. In this study, we tested whether TNF-related activation-induced cytokine (TRANCE), a new member of the TNF superfamily, possesses angiogenic activity in vitro and in vivo. TRANCE stimulated DNA synthesis, chemotactic motility, and capillary-like tube formation in primary cultured human umbilical vein endothelial cells (HUVECs). Both Matrigel plug assay in mice and chick chorioallantoic membrane assay revealed that TRANCE potently induced neovascularization in vivo. TRANCE had no effect on vascular endothelial growth factor (VEGF) expression in HUVECs and TRANCE-induced angiogenic activity was not suppressed by VEGF-neutralizing antibody, implying that TRANCE-induced angiogenesis may be the result of its direct action on endothelial cells. TRANCE evoked a time- and dose-dependent activation of the mitogen-activated protein kinases ERK1/2 and focal adhesion kinase p125(FAK) in HUVECs, which are closely linked to angiogenesis. These signaling events were blocked by the Src inhibitor PP1 or the phospholipase C (PLC) inhibitor. Furthermore, these inhibitors and the Ca(2+) chelator BAPTA-AM suppressed TRANCE-induced HUVEC migration. These results indicate that the angiogenic activity of TRANCE is mediated through the Src-PLC-Ca(2+) signaling cascade upon receptor engagement in endothelial cells, suggesting the role of TRANCE in neovessel formation under physiological and pathological conditions.
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PMID:TNF-related activation-induced cytokine (TRANCE) induces angiogenesis through the activation of Src and phospholipase C (PLC) in human endothelial cells. 1174 51

Stimulation of human platelets with von Willebrand factor (vWF) induces the rapid tyrosine phosphorylation of several proteins, but very little is known on the tyrosine kinases involved in this process. In the present work, we investigated and compared the activation of two related tyrosine kinases expressed in platelets: the proline-rich tyrosine kinase 2 (Pyk2) and the focal adhesion kinase (FAK). Both kinases were tyrosine phosphorylated upon vWF interaction with glycoprotein Ib-IX-V complex, but with different mechanisms. Tyrosine phosphorylation of FAK was totally dependent on thromboxane A2 production, and was inhibited by the integrin alphaIIbeta3 antagonist RGDS peptide. Moreover, chelation of intracellular calcium or inhibition of protein kinase C (PKC) totally blocked vWF-induced tyrosine phosphorylation of FAK, indicating that this event is downstream phospholipase A2 and phospholipase C activation. By contrast, tyrosine phosphorylation of Pyk2 was only partially reduced by aspirin and RGDS, and was not affected by either calcium chelation or PKC inhibition, suggesting that activation of this kinase does not require phospholipase-mediated signalling. Both FAK and Pyk2 translocated to the cytoskeleton upon vWF stimulation of human platelets by a mechanism depending on agonist-induced actin polymerisation. Prevention of cytoskeletal relocation of Pyk2 and FAK by cytochalasin D totally blocked vWF-induced tyrosine phosphorylation of both kinases. Finally, phosphorylation of Pyk2 induced by vWF, but not by thrombin, was inhibited by piceatannol, suggesting that this kinase lies downstream Syk. These results demonstrate that both Pyk2 and FAK are involved in platelet stimulation by vWF, but indicate that only Pyk2 may play a role in the early signal transduction events activated by ligand binding to glycoprotein Ib-IX-V.
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PMID:Proline-rich tyrosine kinase 2 and focal adhesion kinase are involved in different phases of platelet activation by vWF. 1191 84

Tumor invasion marks a critical point in cancer progression; it is a harbinger of morbidity and mortality. Thus, the cellular events that enable the invasive phenotype are under intense investigation. Epstein-Barr virus (EBV) is associated with a number of cancers, including Burkitt lymphoma (BL) and nasopharyngeal carcinoma (NPC) and is suspected to contribute to their tumorigenesis. On average, 8% of gastric carcinomas have been shown to carry this virus. To explore whether the presence of EBV in gastric carcinoma contributes to tumor progression in this predominantly invasive carcinoma, we examined a panel of 2 in vitro EBV-infected human gastric cancer cell line sublines and their mock-infected AGS parental control line. We found EBV infection caused a marked increase in transmigration of a Matrigel barrier (415% and 303%, p < 0.05, for the 2 infected lines). This correlated with increased motility of these sublines (233% and 140%, p < 0.05). As this pattern of increased motility leading to a more pronounced enhancement of invasion has been noted in other tumor cells, we explored the roles of autocrine signaling pathways previously implicated in carcinoma motility and invasion. Inhibitors to the epidermal growth factor receptor (EGFR) (PD153035), phospholipase C (PLC) (U73122), extracellular-signal regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) (PD089035) and PI-3 kinase (Wortmannin) were not informative. These data suggest that EBV increases migration of AGS cells by a mechanism independent of these autocrine growth factor-induced pathways. Instead, we found that the EBV-infected cells presented increased focal adhesion kinase (FAK) phosphorylation. These findings suggest a role for integrin-mediated signaling in promoting EBV-associated invasiveness.
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PMID:EBV-expressing AGS gastric carcinoma cell sublines present increased motility and invasiveness. 1211 96

Angiotensin II (AngII) plays a critical role in control of cardiovascular and renal homeostasis. In addition to its physiological action as a vasoconstrictor, growing evidence supports the notion that AngII contributes to cardiovascular diseases such as hypertension, atherosclerosis, and heart failure. The physiological and pathological actions of AngII in adults are mediated largely via the AngII type 1 receptor (AT1R), a heterotrimeric G-protein-coupled receptor (GPCR). Besides coupling with heterotrimeric G proteins to activate phospholipase C-beta (PLC-beta), AT1R also activates receptor tyrosine kinases (PDGF-R, EGF-R and IGF-R) and non-receptor tyrosine kinases (Src, Fyn, Yes, proline-rich tyrosine kinase 2 (Pyk2), focal adhesion kinase (FAK) and JAK2). These tyrosine kinases play critical roles in AngII-stimulated cell signal events.
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PMID:Angiotensin II signaling pathways mediated by tyrosine kinases. 1267 64

1. The human orphan G-protein coupled receptor bombesin receptor subtype 3 (hBRS-3) was screened for peptide ligands by a Ca(2+)mobilization assay resulting in the purification and identification of two specific ligands, the naturally occurring VV-hemorphin-7 (VV-H-7) and LVV-hemorphin-7 (LVV-H-7), from human placental tissue. These peptides were functionally characterized as full agonists with unique specificity albeit low affinity for hBRS-3 compared to other bombesin receptors. 2. VV-H-7 and LVV-H-7 induced a dose-dependent response in hBRS-3 overexpressing CHO cells, as well as in NCI-N417 cells expressing the hBRS-3 endogenously. The affinity of VV-H-7 was higher in NCI-N417 cells compared to overexpressing CHO cells. In detail, the EC(50) values were 45+/-15 microM for VV-H-7 and 183+/-60 microM for LVV-H-7 in CHO cells, and 19+/-6 microM for VV-H-7 and 38+/-18 microM for LVV-H-7 in NCI-N417 cells. Other hemorphins had no effect. Gastrin-releasing peptide (GRP) and neuromedin B (NMB) showed similar EC(50) values of 13-20 microM (GRP) and of 1-2 microM (NMB) on both cell lines. 3. Structure-function analysis revealed that both the N-terminal valine and the C-terminal phenylalanine residues of VV-H-7 are critical for the ligand-receptor interaction. 4. Endogenous hBRS-3 in NCI-N417 activated by VV-H-7 couples to phospholipase C resulting in changes of intracellular calcium, which is initially released from an inositol trisphosphate (IP(3))-sensitive store followed by a capacitive calcium entry from extracellular space. 5. VV-H-7-induced hBRS-3 activation led to phosphorylation of p42/p44-MAP kinase in NCI-N417 cells, but did not stimulate cell proliferation. In contrast, phosphorylation of focal adhesion kinase (p125(FAK)) was not observed.
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PMID:Identification and functional characterization of hemorphins VV-H-7 and LVV-H-7 as low-affinity agonists for the orphan bombesin receptor subtype 3. 1272 Oct 98

Activation of classical G protein-coupled receptors (GPCRs) like the mammalian gonadotropin-releasing hormone receptor (GnRHR) typically stimulates heterotrimeric G protein molecules that subsequently activate downstream effectors. Receptor activation of heterotrimeric G protein pathways primarily controls intermediary cell metabolism by elevation or diminution of soluble cytoplasmic second messenger molecules. We have demonstrated here that stimulation of the GnRHR also results in a dramatic change in both cell adhesion and superstructural morphology. Gonadotropin-releasing hormone (GnRH) receptor activation rapidly increases the capacity of HEK293 cells expressing the GnRHR to remain matrix-adherent in the face of fluid insults. Coinciding with this profound elevation in matrix adherence, we demonstrated a GnRH-induced alteration in both cell morphology and the de novo generation of polymerized actin structures. GnRH induction of cytoskeletal remodeling was correlated with significant increases in the tyrosine phosphorylation status of a series of cytoskeletal associated proteins, e.g. focal adhesion kinase (FAK), c-Src, and microtubule-associated protein kinase (MAPK or ERK1/2). The activation of the distal downstream effector ERK1/2 was demonstrated to be sensitive to the disrupters of cytoskeletal rearrangement, cytochalasin D and latrunculin B. In addition to the sensitivity of ERKs to cytoskeletal integrity, GnRH-induced FAK and c-Src kinase activation were sensitive to these agents and the fibronectin-integrin antagonistic RGDS peptide. Activation of ERK was dependent on its protein-protein assembly with FAK and c-Src at focal adhesion complexes. Induction of the cell remodeling event leading to this signaling complex assembly occurred primarily via GnRHR activation of the monomeric G protein Rac but not RhoA. These findings demonstrated a clear divergence of GnRHR signaling via the Rac monomeric G protein focal adhesion signaling complex assembly and cytoskeletal remodeling independent of the classical heterotrimeric G protein-controlled phospholipase C-beta pathway.
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PMID:Cytoskeletal reorganization dependence of signaling by the gonadotropin-releasing hormone receptor. 1455 94

The c-Met receptor tyrosine kinase and its ligand, hepatocyte growth factor (HGF), have been implicated in the development and progression of several human cancers and are attractive targets for cancer therapy. PHA-665752 was identified as a small molecule, ATP-competitive, active-site inhibitor of the catalytic activity of c-Met kinase (K(i) 4 nM). PHA-665752 also exhibited >50-fold selectivity for c-Met compared with a panel of diverse tyrosine and serine-threonine kinases. In cellular studies, PHA-665752 potently inhibited HGF-stimulated and constitutive c-Met phosphorylation, as well as HGF and c-Met-driven phenotypes such as cell growth (proliferation and survival), cell motility, invasion, and/or morphology of a variety of tumor cells. In addition, PHA-665752 inhibited HGF-stimulated or constitutive phosphorylation of mediators of downstream signal transduction of c-Met, including Gab-1, extracellular regulated kinase, Akt, signal transducer and activator of transcription 3, phospholipase C gamma, and focal adhesion kinase, in multiple tumor cell lines in a pattern correlating to the phenotypic response of a given tumor cell. In in vivo studies, a single dose of PHA-665752 inhibited c-Met phosphorylation in tumor xenografts for up to 12 h. Inhibition of c-Met phosphorylation was associated with dose-dependent tumor growth inhibition/growth delay over a repeated administration schedule at well-tolerated doses. Interestingly, potent cytoreductive activity was demonstrated in a gastric carcinoma xenograft model. Collectively, these results demonstrate the feasibility of selectively targeting c-Met with ATP-competitive small-molecules and suggest the therapeutic potential of targeting c-Met in human cancers.
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PMID:A selective small molecule inhibitor of c-Met kinase inhibits c-Met-dependent phenotypes in vitro and exhibits cytoreductive antitumor activity in vivo. 1461 33


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