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)

We examined the possibility that the neuroprotective effects of Li+ would depend upon the patterns of neuronal death, apoptosis versus necrosis, and whether Ca2+ as well as phosphoinositide 3-kinase (PI3-K) would mediate the neuroprotective effect of Li+. Cortical neurons treated with Li+ showed marked increase in [Ca2+]i within 2 min. Addition of BAPTA-acetoxymethyl ester, a selective Ca2+ chelator, abrogated the antiapoptotic effect of Li+. PI3-K was activated rapidly within 1 min after exposure to Li+, which mediated Ca2+-dependent neuroprotective effects of Li+. Activated PI3-K seemed to increase [Ca2+]i via the phospholipase Cgamma (PLCgamma) pathway. Antiapoptosis action of Li+ was prevented in the presence of U-73122, a selective phospholipase C inhibitor, and was not observed in PLCgamma1-null fibroblasts. In contrast to antiapoptosis action, administration of Li+ did not prevent neuronal cell necrosis by excitotoxicity or free radicals. Li+ selectively prevents apoptosis by increasing [Ca2+]i through activation of PI3-K and PLCgamma pathways.
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PMID:Calcium-dependent prevention of neuronal apoptosis by lithium ion: essential role of phosphoinositide 3-kinase and phospholipase Cgamma. 1286 27

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.
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PMID:Requirement of Gbetagamma and c-Src in D2 dopamine receptor-mediated nuclear factor-kappaB activation. 1286 50

Recent works have documented that the stimulation of the mu-opioid receptor (MOR) can activate phosphoinositide-specific phospholipase C (PI-PLC). Here I demonstrate that PLC beta 3 isoform activated by beta gamma subunit of G-protein (G beta gamma) in the brain may contribute to the negative modulation for supraspinal antinociception induced by morphine in mice. In immunohistochemical studies, phosphoinositide 3-kinase (PI3K) was detected in the membrane of the cell soma and the immunoreactivity of PI3K (PI3K-IR) was almost overlapped with MOR-IR and PLC gamma 1-IR in the periaqueductal gray matter (PAG) that is considered to be one of the most important sites for the expression of MOR-mediated antinociception. Morphine produced a marked increase in the protein level of membrane-bound PLC gamma 1, and this increase induced by morphine was significantly inhibited by intracerebroventricullar (i.c.v.) pretreatment with PI3K inhibitors at the dosage that suppressed the morphine-induced supraspinal antinociception. Furthermore, morphine also caused a robust increase in the number of phosphorylated-PLC gamma 1 (p-PLC gamma 1) expressing cells in the PAG. It is worthwhile to note that MOR-IR was overlapped with p-PLC gamma 1-IR in the same cells that also contained PI3K in this region. Based on these findings, the next experiment was designed to investigate whether a deletion of the PLC gamma 1 gene by i.c.v. pretreatment with antisense oligodeoxynucleotide (AS-ODN) against PLC gamma 1 could affect the antinociception induced by MOR agonists. Pretreatment with AS-ODN against PLC gamma 1 revealed a significant inhibition of supraspinal antinociception induced by MOR-agonists. In addition, the morphine-induced supraspinal antinociception was suppressed by the blockade of the G beta gamma subunit that can directly activate both PI3K and PLC gamma 1. Moreover, mice lacking the gene for inositol 1,4,5-trisphosphate (IP3)-sensitive receptors, which can modulate the release of Ca2+ from the endoplasmic reticulum, exhibited a significant inhibition of the morphine-induced antinociception. Collectively, these findings raise the possibility that the activation of the PLC pathway associated with the stimulation of PI3K and/or G beta gamma is implicated in supraspinal antinociception induced by MOR agonists in mice.
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PMID:[Direct involvement of the supraspinal phosphoinositide 3-kinase/phospholipase C gamma 1 pathway in the mu-opioid receptor agonist-induced supraspinal antinociception in the mouse]. 1288 52

Somatostatin and its analogue octreotide have been used for two decades to treat oesophageal variceal haemorrhage. The drug was introduced because of its capacity to decrease portal venous pressure without major side effects. In clinical trials assessing the efficacy of somatostatin and long-acting analogues in arresting variceal haemorrhage, conflicting results have been obtained. Furthermore, in haemodynamic studies evaluating the effects of somatostatin and analogues in patients with cirrhosis, divergent effects were observed. The main reason for these differences is probably related to different affinities of the drugs for different somatostatin receptor subtypes. The effects of somatostatin and analogues are mediated via five different G-protein coupled receptors (somatostatin receptor subtypes 1-5), which regulate the activity of ion channels (Ca2+, K+, Na+ and Cl-) and enzymes (adenyl cyclase, phospholipase C, phospholipase A2, phosphoinositide 3-kinase and guanylate cyclase) responsible for the synthesis or degradation of intracellular second messengers including cyclic AMP, inositol 1,4,5-trisphosphate, diacylglycerol and cyclic GMP. Despite universal use of somatostatin, the cellular and biochemical mechanisms of its effects in portal hypertension are relatively poorly studied and remain incompletely understood. In this review, we summarize relevant signal transduction of somatostatin and analogues, the haemodynamic effects of the drugs and the possible mechanisms by which these effects are mediated.
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PMID:Pharmacological rationale for the use of somatostatin and analogues in portal hypertension. 1294 Sep 22

Neutrophils, a major type of blood leukocytes, are indispensable for host defense of bacterial infections. Directed migration in a gradient of chemotactic stimuli enables these cells to rapidly find the site of infection and destroy the invading pathogens. Chemotactic factors bind to seven-transmembrane-domain receptors and activate heterotrimeric G-proteins. Downstream of these proteins a complex interrelated signaling network is activated in human neutrophils. Stimulation of phospholipase C beta results in activation of protein kinase C isoforms and increases in cytosolic calcium. Activation of the enzyme phosphoinositide 3-kinase results in increased production of phosphatidylinositol 3,4,5-trisphosphate and phosphatidyl 3,4-bisphosphate. In addition, small GTP-binding proteins of the Rho family, the mitogen-activated protein kinase cascade, tyrosine kinases and protein phosphatases are activated. The enzyme phosphoinositide 3-kinase and the small cytosolic GTP-binding proteins Rho and Rac emerge as key regulators of neutrophil migration. A steep internal gradient of phosphatidylinositol 3,4,5-trisphosphate, with a high concentration in the leading lamellae, is thought to regulate polarized actin polymerization and formation of protrusions, together with Rac which may be more directly involved in initiating actin reorganization. Rho may regulate localized myosin activation, tail retraction, cell body traction and dynamics of adhesion. The impact of these different signaling pathways on reversible actin polymerization, development of polarity, reversible adhesion and migration, and the putative targets of these pathways in neutrophils, are reviewed in this article. Insight into mechanisms regulating migration of neutrophils could potentially lead to novel therapeutic strategies for counteracting chronic activation of neutrophils which leads to tissue damage.
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PMID:Signaling to migration in neutrophils: importance of localized pathways. 1296 2

Anaplastic large-cell lymphomas (ALCLs) are lymphomas of T or null phenotype often associated with a chromosomal translocation, t(2;5)(p23;q35). This translocation leads to the expression of a hybrid protein consisting of the N-terminal portion of nucleophosmin (NPM) and the intracellular domain of the anaplastic lymphoma kinase (ALK). NPM-ALK possesses a constitutive tyrosine kinase activity responsible for its oncogenic property through activation of downstream effectors such as phospholipase C gamma (PLC-gamma) and the type IA phosphoinositide 3-kinase. Here, we show that the Src-kinases, particularly pp60(c-src), associate with and are activated by NPM-ALK expression in various cells, and in cell lines established from patients with ALCL. The kinase activity and the tyrosine 418 of NPM-ALK are required for its association with Src-kinases. Y418F mutation of NPM-ALK impaired its association with Src-kinases and strongly reduced the proliferation rate of Ba/F3 cells. In agreement, Src-kinase inhibitors or pp60(c-src) siRNA significantly decreased the proliferation rate of NPM-ALK-positive ALCL cell lines. Moreover, using active or inactive forms of pp60(c-src) and NPM-ALK, we provide evidence that NPM-ALK is a potential substrate of pp60(c-src). Overall, our data place Src-kinases as new important downstream effectors of NPM-ALK and as attractive potential therapeutic targets for new ALCL treatment.
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PMID:Nucleophosmin-anaplastic lymphoma kinase of anaplastic large-cell lymphoma recruits, activates, and uses pp60c-src to mediate its mitogenicity. 1456 42

The Tec kinase Btk is an important regulator of antigen receptor activation of phospholipase C-gamma (PLC-gamma). Data from Carpenter and colleagues (Saito et al., this issue of Immunity) now suggest that Btk also activates phosphatidylinositol-4-phosphate 5-kinase (PIP5K), thereby stimulating a positive feedback loop that generates PI(4,5)P2, the substrate for both phosphoinositide 3-kinase (PI3K) and PLC-gamma.
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PMID:Amplifying Btk's signal. 1461 54

Intracellular signaling by most cell surface receptors requires the generation of two major second messengers, phosphatidylinositol-3,4,5-trisphosphate (PtdIns-3,4,5-P3) and inositol-1,4,5-trisphosphate (IP3). The enzymes that produce these second messengers, phosphoinositide 3-kinase (PI3K) and phospholipase C (PLC), utilize a common substrate, phosphatidylinositol-4,5-bisphosphate (PtdIns-4,5-P2). Until now, it has not been clear whether de novo PtdIns-4,5-P2 synthesis is necessary for PtdIns-3,4,5-P3 and IP3 production. Here we show that BTK, a member of the Tec family of cytoplasmic protein tyrosine kinases, associates with phosphatidylinositol-4-phosphate 5-kinases (PIP5Ks), the enzymes that synthesize PtdIns-4,5-P2. Upon B cell receptor activation, BTK brings PIP5K to the plasma membrane as a means of generating local PtdIns-4,5-P2 synthesis. This enzyme-enzyme interaction provides a shuttling mechanism that allows BTK to stimulate the production of the substrate required by both its upstream activator, PI3K, and its downstream target, PLC-gamma2.
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PMID:BTK regulates PtdIns-4,5-P2 synthesis: importance for calcium signaling and PI3K activity. 1461 49

Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P(2)) plays a central role in regulating the actin cytoskeleton as a substrate for phosphoinositide 3-kinase and phospholipase C as well as by binding directly to proteins that control the processes of actin monomer sequestration, filament severing, capping, nucleation, cross-linking, and bundling (Ma, L., Cantley, L. C., Janmey, P. A., and Kirschner, M. W. (1998) J. Cell Biol. 140, 1125-1136; Hinchliffe, K. (2000) Curr. Biol. 10, R104-R1051). Three related phosphatidylinositol 4-phosphate 5-kinases (PI(4)P 5-kinases) have been identified in mammalian cells (types Ialpha, Ibeta, and Igamma) and appear to play distinct roles in actin remodeling. Here we have identified a fourth member of this family by searching the human genome and EST data bases. This new protein, which we have designated phosphatidylinositol phosphate kinase homolog (PIPKH), is expressed at relatively high levels in brain and testis. Immunoprecipitates of PIPKH expressed in mammalian cells contain PI(4)P 5-kinase activity, but this activity is not affected by mutations in residues that inactivate other type I PI(4)P 5-kinases. We show that the PI(4)P 5-kinase activity in PIPKH immunoprecipitates can be explained by the ability of PIPKH to heterodimerize with other type I PI(4)P 5-kinases. Transfection of 293t cells with PIPKH resulted in >8-fold increase in total phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P(3)) without a significant net increase in total PI(4,5)P(2). When coexpressed with PIPKH, green fluorescent protein (GFP) fusion construct of the pleckstrin homology domain from Bruton's tyrosine kinase (GFP-BTK-PH) localized in intracellular vesicular structures, suggesting an unusual intracellular site of PI(3,4,5)P(3) production. Finally, expression of PIPKH induced the reorganization of actin from predominantly stress fibers to predominantly foci and comets similar to those observed previously in cells infected with the intracellular pathogen Listeria or transfected with recombinant PIPKIalpha. These results suggest that PIPKH acts as a scaffold to localize and regulate type I PI(4)P 5-kinases and the synthesis of PI(3,4,5)P(3).
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PMID:Identification and characterization of a phosphoinositide phosphate kinase homolog. 1470 39

We demonstrated recently that norepinephrine activates Ca2+ -permeable nonselective cation channels (NSCCs) in Chinese hamster ovary cells stably expressing alpha1A-adrenergic receptors (CHO-alpha1A). Moreover, extracellular Ca2+ through NSCCs plays essential roles in norepinephrine-induced arachidonic acid release. The purpose of the present study was to identify the G proteins involved in the activation of NSCCs and arachidonic acid release by norepinephrine. For these purposes, we used U73122, an inhibitor of phospholipase C (PLC), and dominant negative mutants of G12 and G13 (G12G228A and G13G225A, respectively). U73122 failed to inhibit NSCCs activation by norepinephrine. The magnitudes of norepinephrine-induced extracellular Ca2+ influx in CHO-alpha1A microinjected with G13G225A were smaller than those in CHO-alpha1A. In contrast, the magnitudes of norepinephrine-induced extracellular Ca2+ influx in CHO-alpha1A microinjected with G12G228A were similar to those in CHO-alpha1A. In addition, neither a Rho-associated kinase (ROCK) inhibitor nor a phosphoinositide 3-kinase inhibitor affected norepinephrine-induced extracellular Ca2+ influx. G13G225A, but not G12G228A, also inhibited arachidonic acid release partially. These results demonstrate that 1) the Gq/PLC-pathway is not involved in NSCCs activation by norepinephrine, 2) G13 couples with CHO-alpha1A and plays important roles for norepinephrine-induced NSCCs activation, 3) neither ROCK- nor PI3K-dependent cascade is involved in NSCCs activation, and 4) G13 is involved in norepinephrine-induced arachidonic acid release in CHO-alpha1A.
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PMID:Characterization of G proteins involved in activation of nonselective cation channels and arachidonic acid release by norepinephrine/alpha1A-adrenergic receptors. 1476 86


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