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)

A new method has been developed to analyze the primary products of phospholipid peroxidation. The procedure utilizes the ability of phospholipase C to hydrolyze phospholipid hydroperoxides to their corresponding diacylglycerol derivatives. 1-Palmitoyl-2-linoleoylphosphatidylcholine (1P,2L-GPC), 1-stearoyl-2-linoleoylphosphatidylcholine (1S,2L-GPC), and 1-stearoyl-2-arachidonylphosphatidylcholine (1S,2A-GPC) were autoxidized. The diacylglycerol hydroxides derived from the phosphatidylcholine hydroperoxides were separated by reverse-phase high-pressure liquid chromatography (RP-HPLC) and normal-phase high-pressure liquid chromatography (NP-HPLC). 1P,2L-diglyceride (1P,2L-DG) and 1P,2A-DG products were easily separated from 1S,2L-DG and 1S,2A-DG products by RP-HPLC. The linoleate diglyceride oxidation mixture was separated into the 13-trans/cis, 13-trans/trans, 9-trans/cis, and 9-trans/trans isomers by NP-HPLC. Likewise, 1P,2A-DG and 1S,2A-DG oxidation products were resolved into the 15-trans/cis, 15-trans/trans, 12-trans/cis, 11-trans/cis, 9-trans/cis, 8-trans/cis, and 5-trans/cis isomers. In both of the above cases, the 1,2-diacylglycerol isomers could be separated from the 1,3 isomers. Moreover, the diastereomers of the 9-, 8-, and 5-hydroxides could be separated. Each of the diacylglycerol oxidation products was characterized by (1) proton nuclear magnetic resonance (proton NMR), (2) electron ionization-mass spectrometry (EI-MS), and (3) NP-HPLC of the corresponding fatty acids. The diacylglycerol analysis provided the same results for the autoxidation of 1P,2L-GPC as the fatty acid methyl ester analysis. In addition, when 1S,2A-GPC was autoxidized in the presence of 5% alpha-tocopherol, both diastereomers of the 5-hydroxide were observed in the same proportions as the other hydroxides.
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PMID:A phospholipase C protocol for phospholipid peroxidation analysis. 297 43

1. Pharmacological characterization of different lysophosphatidylcholines was performed based on their effect on the Ca2+ sensitivity of contraction in alpha-toxin-permeabilized rat mesenteric arteries. Furthermore, the effect of noradrenaline on [3H]-myristate-labelled lysophosphatidylcholine levels was assessed, to investigate whether lysophosphatidylcholines could be second messengers. 2. Palmitoyl or myristoyl L-alpha-lysophosphatidylcholine increased the sensitivity to Ca2+, whereas lysophosphatidylcholines containing other fatty acids had less or no effect. 3. L-alpha-phosphatidylcholine, L-alpha-glycerophosphorylcholine, palmitic acid, myristic acid and choline, potential metabolites of lysophosphatidylcholines, did not affect contractions. 4. Noradrenaline (GTP was required) and GTP gamma S increased the sensitivity to Ca2+, and GDP-beta-S inhibited the effect of noradrenaline. Lysophosphatidylcholines, however, had no requirement for GTP and caused sensitization in the presence of GDP-beta-S. 5. Calphostin C, a relatively specific protein kinase C inhibitor, did not affect contraction induced by Ca2+, but abolished the sensitizing effect of lysophosphatidylcholine. 6. Noradrenaline caused no measurable changes in the levels of [3H]-myristate-labelled phosphatidylcholine and lysophosphatidylcholine at 30 s and 5 min stimulation. 7. These results suggest that lysophosphatidylcholines can increase Ca2+ sensitivity through a G-protein-independent, but a protein kinase C-dependent mechanism. However, the role for lysophosphatidylcholines as messengers causing Ca2+ sensitization during stimulation with noradrenaline remains uncertain because no increase in [3H]-myristate labelled lysophosphatidylcholine could be measured during noradrenaline stimulation.
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PMID:Increase by lysophosphatidylcholines of smooth muscle Ca2+ sensitivity in alpha-toxin-permeabilized small mesenteric artery from the rat. 888 21

Mobilization of intracellular Ca2+ is a critical cellular response to lysophosphatidic acid (LPA) in many cell types. Recent identification of endothelial differentiation gene (Edg) 2 and Edg4 as subtypes of G protein-coupled receptors for LPA allowed examination of the Ca2+ mobilization mediated specifically by each subtype. To reduce endogenous background levels while enhancing recombinant receptor-specific signals, the aequorin luminescence method was used to quantify cytoplasmic Ca2+ levels. In TAg-Jurkat T cells transiently co-transfected with apoaequorin and human Edg2 or Edg4 cDNA, LPA dose-dependently increased light emission triggered by increased Ca2+ bound to aequorin. N-Palmitoyl-L-serine-phosphoric acid and N-palmitoyl-L-tyrosine-phosphoric acid, which had been previously shown to be antagonists for Xenopus laevis LPA receptors, did not antagonize the Ca2+-mobilizing effects of Edg2 and Edg4. Surprisingly, they acted as agonists or partial agonists for Edg2 and Edg4. The Ca2+ mobilization by Edg2 and Edg4 was further characterized in stable transfectants of rat HTC4 hepatoma cells. By using the fura-2 fluorescence method, a difference in the kinetics of Ca2+ flux with Edg2 and Edg4 was observed. With Edg2, but not Edg4, the initial increase in the Ca2+ concentration was followed by a sustained influx of extracellular Ca2+. The coincident production of inositol phosphates and the inhibition of Ca2+ mobilization by the phospholipase C inhibitor U73122 strongly suggested that Edg2 and Edg4 mobilize Ca2+ through inositol trisphosphate generated by phospholipase C activation. Pertussis toxin almost completely blocked LPA-induced Ca2+ mobilization by Edg2 but only partially blocked that by Edg4, which suggests that Edg2 transduces Ca2+ mobilization largely through pertussis toxin-sensitive Gi proteins, whereas Edg4 requires both Gi and Gq.
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PMID:Recombinant human G protein-coupled lysophosphatidic acid receptors mediate intracellular calcium mobilization. 980 23

We examined the mechanism of action of lysophosphatidylcholine (LPC), which is suggested to be involved in the pathogenesis of atherosclerosis and inflammatory disorders, in HL-60 leukaemia cells. Extracellular 1-palmitoyl LPC increased the intracellular Ca2+ concentration in association with production of inositol phosphate. These actions of LPC were markedly inhibited by treatment of the cells with pertussis toxin and U73122, a phospholipase C inhibitor. The lipid-induced stimulation of the phospholipase C/Ca2+ system was also attenuated in the dibutyryl cAMP-induced differentiated (neutrophil-like) cells, in which phospholipase C activation induced by NaF or formyl-Met-Leu-Phe was enhanced. In contrast with the stimulatory action of 1-palmitoyl LPC, 1-stearoyl LPC was inhibitory for the phospholipase C/Ca2+ system stimulated by NaF as well as by 1-palmitoyl LPC or other Ca2+-mobilizing agonists. In a cell-free system, only an inhibitory effect on phospholipase C activity was observed even by 1-palmitoyl LPC; 1-stearoyl LPC was more inhibitive than 1-palmitoyl LPC. Taken together, these results suggest that atherogenic and inflammatory LPC exerts both stimulatory and inhibitory actions on the phospholipase C/Ca2+ system depending on the species of fatty acid residue of the lipid; the stimulatory effect is possibly mediated through G-protein-coupled receptors; the inhibitory effect might be caused by dysfunction of the components involved in the enzyme system owing to the amphiphilic nature of the lipid. 1-Palmitoyl LPC prefers the former receptor stimulation at least in intact cells, but 1-stearoyl LPC preferentially exerts the latter inhibitory action.
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PMID:Stimulatory and inhibitory actions of lysophosphatidylcholine, depending on its fatty acid residue, on the phospholipase C/Ca2+ system in HL-60 leukaemia cells. 982 Aug 28