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)

Tumor necrosis factor alpha (TNF alpha), interleukin 1 beta (IL-1 beta), and endotoxin (LPS) are potent pro-inflammatory mediators which induce multiple and diverse biological responses in a wide variety of cell types. However, these pro-inflammatory mediators also have significant overlap and redundancy in their biological effects. This suggests that there is significant diversity in second messenger signal transduction systems induced by these stimuli to explain the diversity in biological responses, as well as significant redundancy. Here we show that one such second messenger common to several proinflammatory stimuli may be phosphatidic acid (PA). Intracellular PA species, which may have intracellular signaling functions, are rapidly induced in P388 monocytic leukemia cells by TNF alpha, IL-1 beta, or LPS. These PA species vary according to the bond type (i.e., sn-1 ester vs. ether vs. vinyl ether), acyl chain length, and the degree of saturation in the sn-1 and sn-2 positions. Although PA itself may have direct second messenger activities, many of the PA species induced are converted to diacylglycerol species (DG), which are structurally distinct from the DGs generated by phosphatidylcholine-specific phospholipase C (PC-PLC). Lisofylline [(R)-1-(5-hydroxyhexyl)-3,7-dimethylxanthine; LSF] selectively inhibits generation of selected species of PA in P388 cells induced by TNF alpha, IL-1 beta or LPS. TNF alpha-induced sphingomyelin hydrolysis, PLC-mediated PC hydrolysis, and DG kinase-mediated PA formation or TNF alpha-induced NF-kappa B activation and apoptosis are not inhibited by LSF. LSF has a marked protective effect in a variety of acute inflammatory animal models that may be due to inhibition of this shared second messenger pathway involving PA.
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PMID:Potential role for phosphatidic acid in mediating the inflammatory responses to TNF alpha and IL-1 beta. 770 34

Certain phosphatidic/plasmanic/plasmenic acid (PA) species function as lipid intermediates in cell activation and may function directly as intracellular signaling molecules. PA can also be dephosphorylated to 1,2-diradyl-sn-glycerol by phosphatidate phosphohydrolase. Treatment of various cell types, including murine P388 monocytic leukemia cells, with bacterial lipopolysaccharide rapidly stimulates large increases in PA and PA-derived diradylglycerol. Pentoxifylline, 1-(5-oxohexyl)-3,7-dimethylxanthine, inhibits lipopolysaccharide-stimulated formation of PA in P388 cells at high concentrations (IC50 = 500 microM). Lisofylline [1-(5R-hydroxyhexyl)-3,7-dimethylxanthine] is a unique metabolite of pentoxifylline in humans and is > 800-fold more active as an inhibitor of PA formation than pentoxifylline (IC50 = 0.6 microM). Lisofylline does not inhibit lipopolysaccharide-induced activation of phosphatidylinositol-specific phospholipase C and generation of phosphatidylinositol-derived diradylglycerol. Lisofylline but not pentoxifylline protects BALB/c mice from endotoxin lethality when administered 4 hr after lipopolysaccharide. This protective effect is independent of either agent's effect on suppression of plasma tumor necrosis factor alpha. These data suggest that inhibitors of PA formation may have significant clinical potential in the treatment of sepsis and septic shock.
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PMID:Protection from endotoxic shock in mice by pharmacologic inhibition of phosphatidic acid. 817 Oct 2