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)

Thrombin-induced activation of RhoA and its involvement in the regulation of myosin II light chain(20) phosphorylation (MLC-P) in alpha-toxin permeabilized platelets was investigated. Permeabilized platelets, expressing normal levels of P-selectin, displayed a Ca(2+)-dependent increase in shape change and MLC-P. Thrombin activated RhoA as measured by a rhotekin-binding assay within 30 s of stimulation under conditions of constant [Ca(2+)](i). Under the same conditions and timecourse, thrombin or GTPgammaS induced an increase in MLC-P and platelet shape change which was not dependent on an increase in [Ca(2+)](i). The thrombin- and GTPgammaS-induced MLC-P in constant [Ca(2+)](i) was inhibited by the addition of Y27632, a Rho-kinase inhibitor. This study directly demonstrates that thrombin can activate RhoA in platelets in a timecourse compatible with a role in increasing MLC-P and shape change (not involving an increase in [Ca(2+)](i)). This is also Rho-kinase-dependent.
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PMID:Thrombin-induced activation of RhoA in platelet shape change. 1154 55

It has been previously suggested that leukotriene-induced Ca2+ signalling is mediated through a Rho-dependent process, but neither direct activation of Rho nor a mechanism underlying such signalling has been reported. Accordingly, we used the Rhotekin binding assay to assess RhoA activation in intestinal epithelial cells and observed that RhoA was activated by leukotriene D4 (LTD4). We also found that, within 15 s, activation of RhoA by LTD4 led to an increased association of RhoA with G-protein betagamma (Gbetagamma) and phospholipase C-gamma1 (PLC-gamma1) in the plasma membrane, as evidenced by the results of co-immunoprecipitation, glutathione S-transferase (GST) pulldown assays, and confocal microscopy. Amounts of RhoA increased in both Gbeta and PLC-gamma1 immunoprecipitates within 15 s of LTD4 treatment. An interaction between RhoA, Gbetagamma and PLC-gamma1 is supported by our finding that a GST fusion protein of constitutively active RhoA (GST-RhoAV14) precipitated Gbetagamma and PLC-gamma1 from cell lysates in an agonist-dependent manner. Such an association is also substantiated by our confocal immunofluorescence results, which revealed that LTD4 induction increased co-localization of constitutively active RhoA and PLC-gamma1 to the plasma membrane of cells transfected with enhanced green fluorescent protein L63RhoA. Furthermore, microinjection of neutralizing RhoA antibodies, but not control antibodies, significantly reduced LTD4-induced Ca2+ mobilization. Our results are the first to demonstrate a LTD4-induced activation of RhoA and more importantly its association with PLC-gamma1, which are essential for the PLC-gamma1-mediated calcium mobilization.
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PMID:Leukotriene D4 induces association of active RhoA with phospholipase C-gamma1 in intestinal epithelial cells. 1207 48

Alpha(2)-adrenoceptors potentiate renal vascular responses to angiotensin II via coincident signaling at phospholipase C. This leads to increased activation of the phospholipase C/protein kinase C/c-src pathway. Studies suggest that c-src activates the reduced nicotinamide-adenine dinucleotide phosphate (NADPH) oxidase/superoxide system, and reactive oxygen species stimulate the RhoA/Rho kinase pathway. Therefore, we hypothesized that NADPH oxidase/superoxide and RhoA/Rho kinase are downstream components of the signal transduction pathway that mediate the interaction between alpha(2)-adrenoceptors and angiotensin II on renal vascular resistance. In rat kidneys, both in vivo and in vitro, intrarenal infusions of angiotensin II increased renal vascular resistance, and UK14,304 (alpha(2)-adrenoceptor agonist) enhanced this response. Intrarenal Tempol (superoxide dismutase mimetic) or Y27632 (Rho kinase inhibitor) abolished the interaction between UK14,304 and angiotensin II both in vivo and in vitro. The interaction was also blocked by inhibitors of NADPH oxidase (in vivo using chronic gp91ds-tat administration and in vitro with diphenyleneiodonium). In cultured preglomerular vascular smooth muscle cells, UK14,304 enhanced angiotensin II-induced intracellular superoxide (2-hydroxyethidium production) and potentiated activation of RhoA (Western blot of activated RhoA bound to the binding domain of rhotekin). The interaction between angiotensin II and UK14,304 on superoxide generation and RhoA activation was blocked by inhibitors of phospholipase C (U73312), protein kinase C (GF109203X), c-src (PP1), NADPH oxidase (diphenyleneiodonium), or superoxide (Tempol). We conclude that NADPH oxidase/superoxide and RhoA/Rho kinase are involved in the interaction between alpha(2)-adrenoceptors and angiotensin II on renal vascular resistance by mediating signaling events downstream of the phospholipase C/protein kinase C/c-src pathway.
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PMID:Alpha2-adrenoceptors enhance angiotensin II-induced renal vasoconstriction: role for NADPH oxidase and RhoA. 1825 Mar 67