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)

Protein kinase C (PKC) isoenzymes are essential components of cell signaling. In this study, we investigated the regulation of PKC-alpha in murine B16 amelanotic melanoma (B16a) cells by the monohydroxy fatty acids 12(S)-hydroxyeicosatetraenoic acid [12(S)-HETE] and 13(S)-hydroxyoctadecadienoic acid [13(S)-HODE]. 12(S)-HETE induced a translocation of PKC-alpha to the plasma membrane and focal adhesion plaques, leading to enhanced adhesion of B16a cells to the matrix protein fibronectin. However, 13(S)-HODE inhibited these 12(S)-HETE effects on PKC-alpha. A receptor-mediated mechanism of action for 12(S)-HETE and 13(S)-HODE is supported by the following findings. First, 12(S)-HETE triggered a rapid increase in cellular levels of diacylglycerol and inositol trisphosphate in B16a cells. 13(S)-HODE blocked the 12(S)-HETE-induced bursts of both second messengers. Second, the 12(S)-HETE-increased adhesion of B16a cells to fibronectin was sensitive to inhibition by a phospholipase C inhibitor and pertussis toxin. Finally, a high-affinity binding site (Kd = 1 nM) for 12(S)-HETE was detected in B16a cells, and binding of 12(S)-HETE to B16a cells was effectively inhibited by 13(S)-HODE (IC50 = 4 nM). In summary, our data provide evidence that regulation of PKC-alpha by 12(S)-HETE and 13(S)-HODE may be through a guanine nucleotide-binding protein-linked receptor-mediated hydrolysis of inositol phospholipids.
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PMID:12(S)-hydroxyeicosatetraenoic acid and 13(S)-hydroxyoctadecadienoic acid regulation of protein kinase C-alpha in melanoma cells: role of receptor-mediated hydrolysis of inositol phospholipids. 756 26

The incorporation of 12-lipoxygenase metabolites into phospholipids (PLs) could modify second messengers such as diacylglycerols (DAG) and phosphatidic acids. Incubation of [(14)C]12(S)-HETE (1 microM) with bovine pulmonary artery endothelial cells (BPAEC), resulted in its incorporation in PLs with concentration-dependent kinetics. After a 4 h incubation, the proportion of radioactive phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS) + phosphatidylinositol (PI) isolated by TLC, was 77.9%, 16.4% and 5.7%, respectively. In PC, [(14)C]12(S)-HETE was incorporated at the position 2 of the glycerol. Three major peaks of radioactive PC were isolated on RP-HPLC which were hydrolysed by phospholipase C (PLC). The resulting diacylglycerols were derivatized and identified by GC/MS as 1-oleyl-, 1-stearoyl- and 1-palmitoyl-2-[12-HETE] PC. BPAEC were incubated with [(14)C]12(S)-HETE (1 microM) before stimulation with bradykinin (1 microM). (A) 1-acyl-2-[12-HETE] diacylglycerols were isolated, derivatized and analysed by MS. We identified a major ion with m/z = 926 that corresponds to the molecular ion of authentic 1-stearoyl-2-12(S)-HETE DAG, and 2 other ions with m/z = 924 and 898 that correspond to the molecular ions of 1-oleyl- and 1-palmitoyl-2-12(S)-HETE DAG, respectively. (B) Radioactive PA was isolated and hydrolysed by alkaline phosphatase. The MS of resulting diacylglycerols identified 1-stearoyl-, 1-oleyl-, and 1-palmitoyl-2-12(S)-HETE phosphatidic acids. The quantities of 12-HETE PA and the 3 major 12-HETE diacylglycerols were shown to increase following bradykinin stimulation. Thus, the incorporation of 12(S)-HETE into PLs results in the production of altered phosphatidic acids and diacylglycerols. The time-course of increases in 1-acyl-2-(12-HETE) phosphatidic acids and 1-acyl-2-(12-HETE) diacylglycerols showed maximal concentrations 1 and 2 min after bradykinin stimulation, respectively, followed by the decrease of both compounds. Propranolol, an inhibitor of PA phosphohydrolase, totally abolished the bradykinin-induced increase in 12-HETE DAG while increasing the magnitude and duration of 12-HETE PA release. The inhibiting effect of propranolol on bradykinin-induced increase of 12-HETE DAG demonstrates that 12-HETE PA is the principal precursor for 12-HETE DAG. This affords a novel method for confirming the major role of phospholipase D in PC metabolic pathways triggered during cell signaling.
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PMID:Incorporation of 12(S)-hydroxyeicosatetraenoic acid into the phosphatidylcholine signaling pathway. 865 50

The studies presented here explore intracellular signals resulting from the action of repellents on growth cones. Growth cone challenge with thrombin or thrombin receptor-activating peptide (TRAP) triggers collapse via a receptor-mediated process. The results indicate that this involves activation of cytosolic phospholipase A(2) (PLA(2)) and eicosanoid synthesis. The collapse response to repellents targets at least two functional units of the growth cone, the actin cytoskeleton and substratum adhesion sites. We show in a cell-free assay that thrombin and TRAP cause the detachment of isolated growth cones from laminin. Biochemical analyses of isolated growth cones reveal that thrombin and TRAP stimulate cytosolic PLA(2) but not phospholipase C. In addition, thrombin stimulates synthesis of 12- and 15-hydroxyeicosatetraenoic acid (HETE) from the released arachidonic acid via a lipoxygenase (LO) pathway. A selective LO inhibitor blocks 12/15-HETE synthesis in growth cones and inhibits thrombin-induced growth cone collapse. Exogenously applied 12(S)-HETE mimics the thrombin effect and induces growth cone collapse in culture. These observations indicate that thrombin-induced growth cone collapse occurs by a mechanism that involves the activation of cytosolic PLA(2) and the generation of 12/15-HETE.
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PMID:Thrombin-induced growth cone collapse: involvement of phospholipase A(2) and eicosanoid generation. 1059 66