title: Activation and induction of cytosolic phospholipase A2 by TNF-α mediated through Nox2, MAPKs, NF-κB, and p300 in human tracheal smooth muscle cells.
abstract: Cytosolic phospholipase A(2) (cPLA(2)) plays a pivotal role in mediating agonist-induced arachidonic acid (AA) release for prostaglandin (PG) synthesis during inflammation triggered by tumor necrosis factor-α (TNF-α). However, the mechanisms underlying TNF-α-induced cPLA(2) expression and PGE(2) synthesis in human tracheal smooth muscle cells (HTSMCs) remain unknown. Here, we report that TNF-α-induced cPLA(2) protein and mRNA expression, PGE(2) production, and phosphorylation of p42/p44 MAPK, p38 MAPK, and JNK1/2, which were attenuated by pretreatment with a ROS scavenger [N-acetyl-L-cysteine, (NAC)] and the inhibitors of NADPH oxidase [apocynin (APO) and diphenyleneiodonium chloride (DPI)], MEK1/2 (U0126), p38 MAPK (SB202190), and JNK1/2 (SP600125) or transfection with siRNA of Nox2, p47(phox) , MEK1, p42, p38, or JNK2. TNF-α-induced cPLA(2) expression was also inhibited by pretreatment with a selective NF-κB inhibitor [helenalin (HLN)] or transfection with dominant negative mutants of NF-κB inducing kinase (NIK) or IκB kinase (IKK)α/β. TNF-α-induced NF-κB translocation was blocked by pretreatment with NAC, DPI, APO, or HLN, but not by U0126, SB202190, or SP600125. In addition, pretreatment with curcumin (a p300 inhibitor) or transfection with p300 siRNA blocked cPLA(2) expression and PGE(2) synthesis induced by TNF-α. We further confirmed that p300 was associated with the cPLA(2) promoter which was dynamically linked to histone H4 acetylation stimulated by TNF-α, determined by chromatin immunoprecipitation assay. Association of p300 and histone H4 to cPLA(2) promoter was inhibited by U0126, SB202190, and SP600125. These results suggested that in HTSMCs, activation of p47(phox) , MAPKs, NF-κB, and p300 is essential for TNF-α-induced cPLA(2) expression and PGE(2) release.
authors.affiliation: Department of Nursing, Division of Basic Medical Sciences, Chronic Diseases and Health Promotion Research Center, Chang Gung Institute of Technology, Chia-Yi, Taiwan.
authors.forename: Chiang-Wen
authors.initials: CW
authors.lastname: Lee
authors.forename: Chih-Chung
authors.initials: CC
authors.lastname: Lin
authors.forename: I-Ta
authors.initials: IT
authors.lastname: Lee
authors.forename: Hui-Chun
authors.initials: HC
authors.lastname: Lee
authors.forename: Chuen-Mao
authors.initials: CM
authors.lastname: Yang
mesh_terms: D000098:Acetophenones / Q000494:pharmacology; D000107:Acetylation; D000111:Acetylcysteine / Q000494:pharmacology; D002460:Cell Line; D003474:Curcumin / Q000494:pharmacology; D015232:Dinoprostone / Q000096:biosynthesis; D050881:E1A-Associated p300 Protein / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology; D006657:Histones / Q000378:metabolism; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000201:enzymology*; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000378:metabolism*; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009861:Onium Compounds / Q000494:pharmacology; D054467:Phospholipases A2 / Q000096:biosynthesis*; D010766:Phosphorylation; D012717:Sesquiterpenes / Q000494:pharmacology; D045789:Sesquiterpenes, Guaiane; D014132:Trachea / Q000187:drug effects / Q000201:enzymology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
chemical_list: D000098:Acetophenones; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D006657:Histones; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D009861:Onium Compounds; D012717:Sesquiterpenes; D045789:Sesquiterpenes, Guaiane; D014409:Tumor Necrosis Factor-alpha; C001329:helenalin; C007517:diphenyleneiodonium; C056165:acetovanillone; C056558:CYBB protein, human; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; D050881:E1A-Associated p300 Protein; C494360:EP300 protein, human; D020928:Mitogen-Activated Protein Kinases; D054467:Phospholipases A2; D003474:Curcumin; D015232:Dinoprostone; D000111:Acetylcysteine