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

---

Query: EC:3.1.4.3 (phospholipase C)
18,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The epidermal growth factor (EGF) receptor has an important role in cellular proliferation, and the enzymatic activity of phospholipase C (PLC)-gamma1 is regarded to be critical for EGF-induced mitogenesis. In this study, we report for the first time a phospholipase complex composed of PLC-gamma1 and phospholipase D2 (PLD2). PLC-gamma1 is co-immunoprecipitated with PLD2 in COS-7 cells. The results of in vitro binding analysis and co-immunoprecipitation analysis in COS-7 cells show that the Src homology (SH) 3 domain of PLC-gamma1 binds to the proline-rich motif within the Phox homology (PX) domain of PLD2. The interaction between PLC-gamma1 and PLD2 is EGF stimulation-dependent and potentiates EGF-induced inositol 1,4,5-trisphosphate (IP(3)) formation and Ca(2+) increase. Mutating Pro-145 and Pro-148 within the PX domain of PLD2 to leucines disrupts the interaction between PLC-gamma1 and PLD2 and fails to potentiate EGF-induced IP(3) formation and Ca(2+) increase. However, neither PLD2 wild type nor PLD2 mutant affects the EGF-induced tyrosine phosphorylation of PLC-gamma1. These findings suggest that, upon EGF stimulation, PLC-gamma1 directly interacts with PLD2 and this interaction is important for PLC-gamma1 activity.
...
PMID:The direct interaction of phospholipase C-gamma 1 with phospholipase D2 is important for epidermal growth factor signaling. 1264 82

Glucosylceramide-based glycosphingolipids have been previously demonstrated to regulate negatively the formation of inositol 1,4,5-trisphosphate by phospholipase C-gamma1. In the present study, the depletion of endogenous glucosylceramide by D-t-EtDO-P4 in cultured ECV304 cells induced autophosphorylation of Src kinase at tyrosine residue 418 within the catalytic loop and dephosphorylation of Src kinase at tyrosine residues 529 within the carboxyl-terminal regulatory region. Phosphotransferase activities of Src kinase were also induced in the glucosylceramide-depleted cells. c-Src kinase activity and phosphorylations at Src Tyr-418 and epidermal growth factor (EGF) receptor Tyr-1068 were significantly enhanced by bradykinin in response to 100 nm D-t-EtDO-P4 compared with control cells. The phosphorylation and dephosphorylation on Tyr-418 and Tyr-529 residues of c-Src were reversed by treatment of 4-amino-5-(4-chlorophenyl)-7-t-butyl(pyrazolo)[3,4-d]pyrimidine (PP2), an inhibitor of Src kinase, in control cells. Glucosylceramide-depleted cells resisted treatment with PP2, and both phosphorylation of Tyr-418 and dephosphorylation of Tyr-529 induced by depletion of glucosylceramide were maintained. Compared with untreated cells, tyrosine phosphorylation of phospholipase C-gamma1 was enhanced by EGF stimulation in glucosylceramide-depleted cells, associated with enhanced tyrosine phosphorylation of the EGF receptor at Tyr-1068 and Tyr-1086 stimulated by EGF. The Src inhibitor, PP2, significantly blocked EGF-induced tyrosine phosphorylation of phospholipase C-gamma1 in control cells, whereas in glucosylceramide-depleted cells, suppression of Src kinase activity by PP2 toward EGF-induced tyrosine phosphorylation of phospholipase C-gamma1 was less significant. Thus the activation of Src kinase by depletion of glucosylceramide-based glycosphingolipids in cultured ECV304 cells is a critical up-stream event in the activation of phospholipase C-gamma1.
...
PMID:Src kinase mediates the regulation of phospholipase C-gamma activity by glycosphingolipids. 1277 Nov 40

The D2 dopamine receptor (D2R) was examined for its ability to mediate nuclear factor-kappaB (NF-kappaB) activation through G proteins. Stimulation of D2R-transfected HeLa cells with its agonist quinpirole induced the expression of a NF-kappaB luciferase reporter and formation of NF-kappaB-DNA complex. This response was blocked by pertussis toxin, and by the Gbetagamma scavengers transducin and beta-adrenergic receptor kinase 1 carboxyl-terminal fragment. Unlike Gi-coupled chemoattractant receptors, D2R activated NF-kappaB without an increase in phospholipase C-beta activity, and the response was only slightly affected by the phosphoinositide 3-kinase inhibitor 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002). In contrast, treatment with genistein and 4-amino-1-tert-butyl-3-(p-methylphenyl)pyrazolo[3,4-d] pyrimidine abolished the induced NF-kappaB activation, suggesting involvement of protein tyrosine kinases. Activation of D2R led to phosphorylation of c-Src at Tyr-418, and expression of a kinase-deficient c-Src inhibited D2R-mediated NF-kappaB activation. The D2R-mediated NF-kappaB activation was not dependent on epidermal growth factor (EGF) receptor transactivation since 4-(3'-chloroanilino)-6,7-dimethoxyquinazoline (AG1478), an EGF receptor-selective tyrphostin used at 1 microM, blocked EGF-induced NF-kappaB activation but not the quinpirole-induced response. In addition, the D2R-mediated NF-kappaB activation was enhanced by over-expression of beta-arrestin 1. These results suggest that D2R-mediated NF-kappaB activation requires Gbetagamma and c-Src, and possibly involves beta-arrestin 1.
...
PMID:Requirement of Gbetagamma and c-Src in D2 dopamine receptor-mediated nuclear factor-kappaB activation. 1286 50

Fibroblast growth factors (FGFs) regulate long bone development by affecting the proliferation and differentiation of chondrocytes. FGF treatment inhibits the proliferation of chondrocytes both in vitro and in vivo, but the signaling pathways involved have not been clearly identified. In this report we show that both the MEK-ERK1/2 and p38 MAPK pathways, but not phospholipase C gamma or phosphatidylinositol 3-kinase, play a role in FGF-mediated growth arrest of chondrocytes. Chemical inhibitors of the MEK1/2 or the p38 MAPK pathways applied to rat chondrosarcoma (RCS) chondrocytes significantly prevented FGF-induced growth arrest. The retinoblastoma family members p107 and p130 were previously shown to be essential effectors of FGF-induced growth arrest in chondrocytes. The dephosphorylation of p107, one of the earliest events in RCS growth arrest, was significantly blocked by MEK1/2 inhibitors but not by the p38 MAPK inhibitors, whereas that of p130, which occurs later, was partially prevented both by the MEK and p38 inhibitors. Furthermore, by expressing the nerve growth factor (NGF) receptor, TrkA, and the epidermal growth factor (EGF) receptor, ErbB1, in RCS cells we show that NGF treatment of the transfected cells caused growth inhibition, whereas EGF did not. FGF- and NGF-induced growth inhibition is accompanied by a strong and sustained activation of ERK1/2 and p38 MAPK and a decrease of AKT phosphorylation, whereas EGF induces a much more transient activation of p38 and ERK1/2 and increases AKT phosphorylation. These results indicate that inhibition of chondrocyte proliferation by FGF requires both ERK1/2 and p38 MAPK signaling and also suggest that sustained activation of these pathways is required to achieve growth inhibition.
...
PMID:Activation of the ERK1/2 and p38 mitogen-activated protein kinase pathways mediates fibroblast growth factor-induced growth arrest of chondrocytes. 1459 93

Due to its pivotal role in the growth factor-mediated tumour cell migration, the adaptor protein phospholipase C-gamma1 (PLC-gamma1) is an appropriate target to block ultimately the spreading of EGFR/c-erbB-2-positive tumour cells, thereby minimising metastasis formation. Here, we present an approach to block PLC-gamma1 activity by using protein-based PLC-gamma1 inhibitors consisting of PLC-gamma1 SH2 domains, which were fused to the TAT-transduction domain to ensure a high protein transduction efficiency. Two proteins were generated containing one PLC-gamma1-SH2-domain (PS1-TAT) or two PLC-gamma1-SH2 domains (PS2-TAT). PS2-TAT treatment of the EGFR/c-erbB-2-positive cell line MDA-HER2 resulted in a reduction of the EGF-mediated PLC-gamma1 tyrosine phosphorylation of about 30%, concomitant with a complete abrogation of the EGF-driven calcium influx. In addition to this, long-term PS2-TAT treatment both reduces the EGF-mediated migration of about 75% combined with a markedly decreased time locomotion of single MDA-HER2 cells as well as decreases the proliferation of MDA-HER2 cells by about 50%. Due to its antitumoral capacity on EGFR/c-erbB-2-positive breast cancer cells, we conclude from our results that the protein-based PLC-gamma1 inhibitor PS2-TAT may be a means for novel adjuvant antitumour strategies to minimise metastasis formation because of the blockade of cell migration and proliferation.
...
PMID:Antitumour effects of PLC-gamma1-(SH2)2-TAT fusion proteins on EGFR/c-erbB-2-positive breast cancer cells. 1471 Feb 34

Keratinocyte migration is critical to reepithelialization during wound repair. The motility response is promoted by growth factors, cytokines, and cytokines produced in the wound bed, including those that activate the epidermal growth factor (EGF) receptor. The Alu-Leu-Arg-negative CXC chemokine interferon-inducible protein 9 (IP-9; also known as CXCL11, I-TAC, beta-R1, and H-174) is produced by keratinocytes in response to injury. As keratinocytes also express the receptor, CXCR3, this prompted us to examine the role and molecular mechanism by which IP-9 regulates keratinocyte motility. Unexpectedly, as CXCR3 liganding blocks growth factor-induced motility in fibroblasts, IP-9 alone promoted motility in undifferentiated keratinocytes (37 +/- 6% of the level of the highly motogenic EGF) as determined in a two-dimensional in vitro wound healing assay. IP-9 even enhanced EGF-induced motility in undifferentiated keratinocytes (116 +/- 5%; P < 0.05 compared to EGF alone), suggesting two separate mechanisms of action. IP-9-increased motility and -decreased adhesiveness required the intracellular protease calpain. The increases in both motility and calpain activity by IP-9 were blocked by pharmacological and molecular inhibition of phospholipase C-beta3 and chelation of calcium, which prevented an intracellular calcium flux. Molecular downregulation or RNA interference-mediated depletion of mu-calpain (calpain 1) but not M-calpain (calpain 2) blocked IP-9-induced calpain activation and motility. In accord with elimination of IP-9-induced de-adhesion, RNA interference-mediated depletion of calpain 1 but not calpain 2 prevented cleavage of the focal adhesion component focal adhesion kinase and disassembly of vinculin aggregates. In comparison, EGF-induced motility of the same undifferentiated keratinocytes requires the previously described extracellular signal-regulated kinase to the M-calpain pathway. These data demonstrate that while both EGF- and IP-9-induced motility in keratinocytes requires calpain activity, the isoform of calpain triggered depends on the nature of the receptor for the particular ligand. Interestingly, physiological nonapoptotic calcium fluxes were capable of activating mu-calpain, implying that the calcium requirement of mu-calpain for activation is attained during cell signaling. This is also the first demonstration of differential activation of the two ubiquitous calpain isoforms in the same cell by different signals.
...
PMID:Interferon-inducible protein 9 (CXCL11)-induced cell motility in keratinocytes requires calcium flux-dependent activation of mu-calpain. 1571 46

A G protein-coupled receptor agonist, angiotensin II (AngII), induces epidermal growth factor (EGF) receptor (EGFR) transactivation possibly through metalloprotease-dependent, heparin-binding EGF (HB-EGF) shedding. Here, we have investigated signal transduction of this process by using COS7 cells expressing an AngII receptor, AT1. In these cells AngII-induced EGFR transactivation was completely inhibited by pretreatment with a selective HB-EGF inhibitor, or with a metalloprotease inhibitor. We also developed a COS7 cell line permanently expressing a HB-EGF construct tagged with alkaline phosphatase, which enabled us to measure HB-EGF shedding quantitatively. In the COS7 cell line AngII stimulated release of HB-EGF. This effect was mimicked by treatment either with a phospholipase C activator, a Ca2+ ionophore, a metalloprotease activator, or H2O2. Conversely, pretreatment with an intracellular Ca2+ antagonist or an antioxidant blocked AngII-induced HB-EGF shedding. Moreover, infection of an adenovirus encoding an inhibitor of G(q) markedly reduced EGFR transactivation and HB-EGF shedding through AT1. In this regard, AngII-stimulated HB-EGF shedding was abolished in an AT1 mutant that lacks G(q) protein coupling. However, in cells expressing AT1 mutants that retain G(q) protein coupling, AngII is still able to induce HB-EGF shedding. Finally, the AngII-induced EGFR transactivation was attenuated in COS7 cells overexpressing a catalytically inactive mutant of ADAM17. From these data we conclude that AngII stimulates a metalloprotease ADAM17-dependent HB-EGF shedding through AT1/G(q)/phospholipase C-mediated elevation of intracellular Ca2+ and reactive oxygen species production, representing a key mechanism indispensable for EGFR transactivation.
...
PMID:G protein coupling and second messenger generation are indispensable for metalloprotease-dependent, heparin-binding epidermal growth factor shedding through angiotensin II type-1 receptor. 1590 75

Bone marrow mesenchymal stem cells (BMMSCs) are pluripotent cells capable of differentiating into several cell types and are thus an attractive cell source for connective tissue engineering. A challenge in such a use is expansion and directed seeding in vitro, requiring proliferation and survival, and directed migration, respectively, prior to functional differentiation. The epidermal growth factor (EGF) receptor (EGFR) is the prototypal growth factor receptor and elicits these responses from a wide variety of stromal, epithelial, and endothelial cells. Ligands for this receptor are appealing for use in tissue engineering because they are relatively resistant to biological extremes and amenable to high-volume production. Therefore, we determined whether an EGFR ligand, EGF, could be used for ex vivo expansion of BMMSCs. EGF stimulated motility in rat and immortalized human BMMSCs. EGF-induced proliferation was observed in immortalized human BMMSCs but was not apparent in rat BMMSCs under our experimental conditions. EGF did not, however, rescue either type of BMMSC from apoptosis due to lack of serum. During our examination of key signaling intermediaries, EGF caused robust phosphorylation of extracellular signal-regulated protein kinase (ERK) and protein kinase B/akt (AKT) but only minimal phosphorylation of EGFR and phospholipase C-gamma in rat BMMSCs, whereas in the human BMMSCs these intermediaries were all strongly activated. EGF also induced robust ERK activation in primary porcine mesenchymal stem cells. EGF pretreatment or cotreatment did not interfere with secondarily induced differentiation of either type of BMMSC into adipogenic or osteogenic lineages. Platelet-derived growth factor (PDGF) effects were similar to but not additive with those elicited by EGF, with some quantitative differences; however, PDGF did interfere with the differentiation of these BMMSCs. These findings suggest that EGFR ligands could be used for ex vivo expansion and direction of BMMSCs.
...
PMID:Epidermal growth factor as a candidate for ex vivo expansion of bone marrow-derived mesenchymal stem cells. 1615 Sep 20

The down-regulation of the epidermal growth factor (EGF) receptor is critical for the termination of EGF-dependent signaling, and the dysregulation of this process can lead to oncogenesis. In the present study, we suggest a novel mechanism for the regulation of EGF receptor down-regulation by phospholipase C-epsilon. The overexpression of PLC-epsilon led to an increase in receptor recycling and decreased the down-regulation of the EGF receptor in COS-7 cells. Adaptor protein complex 2 (AP2) was identified as a novel binding protein that associates with the PLC-epsilon RA2 domain independently of Ras. The interaction of PLC-epsilon with AP2 was responsible for the suppression of EGF receptor down-regulation, since a perturbation in this interaction abolished this effect. Enhanced EGF receptor stability by PLC-epsilon led to the potentiation of EGF-dependent growth in COS-7 cells. Finally, the knockdown of PLC-epsilon in mouse embryo fibroblast cells elicited a severe defect in EGF-dependent growth. Our results indicated that PLC-epsilon could promote EGF-dependent cell growth by suppressing receptor down-regulation.
...
PMID:Phospholipase C-epsilon augments epidermal growth factor-dependent cell growth by inhibiting epidermal growth factor receptor down-regulation. 1795 67

Vasopressin acts on astrocytic Gq protein- and phospholipase C-coupled V1 receptors. In mesangial cells, which also express the V1 receptor, it stimulates cell growth by activating mitogen-activated protein kinase (MAP kinase) secondary to transactivation of the epidermal growth factor (EGF) receptor. Transactivation is an intracellular/extracellular process, in which activation of a Gq or a Gi/o protein-coupled receptor leads to metalloproteinase-catalyzed shedding of an EGF receptor agonist, which stimulates EGF receptors on the same cell and/or its neighbor(s). The goal of the present study was to investigate if vasopressin signaling is mediated by transactivation also in astrocytes and whether such a transactivation is required for its ability to facilitate vector-driven water fluxes. Vasopressin concentrations between 10(-12) and 10(-6) M were found to lead to phosphorylation (activation) of extracellular regulated kinase 1 and 2 (ERK 1/2). Phosphorylation of ERK 1/2 could be completely inhibited by either AG1478, an inhibitor of the EGF receptor-activated tyrosine kinase, or GM6001, an inhibitor of Zn2+-activated metalloproteinases, indicating the involvement of transactivation. Exposure to a hypotonic medium caused an immediate (within one min) increase in cell water volume (demonstrated by decrease of fluorescence quenching of calcein), part of which was dependent upon the presence of vasopressin, added at a concentration of 1 x 10(-8) M. This vasopressin-dependent component persisted throughout the duration of the experiment (22 min). The effect of vasopressin was abolished in the presence of AG1478, indicating its dependence upon transactivation, and by U0126 an inhibitor of the MAP kinase/ERK kinase (MEK), and thus of ERK 1/2 phosphorylation.
...
PMID:Stimulation by vasopressin of ERK phosphorylation and vector-driven water flux in astrocytes is transactivation-dependent. 1848 26


<< Previous 1 2 3 4 5 Next >>

---