TNF-α induces cytosolic phospholipase A2 expression via Jak2/PDGFR-dependent Elk-1/p300 activation in human lung epithelial cells.
Cytosolic phospholipase A2 (cPLA2) plays a pivotal role in mediating agonist-induced arachidonic acid release for prostaglandin (PG) synthesis during inflammation triggered by tumor necrosis factor-α (TNF-α). However, the mechanisms underlying TNF-α-induced cPLA2 expression in human lung epithelial cells (HPAEpiCs) were not completely understood. Here, we demonstrated that TNF-α induced cPLA2 mRNA and protein expression, promoter activity, and PGE2 secretion in HPAEpiCs. These responses induced by TNF-α were inhibited by pretreatment with the inhibitor of Jak2 (AG490), platelet-derived growth factor receptor (PDGFR) (AG1296), phosphoinositide 3 kinase (PI3K) (LY294002), or MEK1/2 (PD98059) and transfection with siRNA of Jak2, PDGFR, Akt, or p42. We showed that TNF-α markedly stimulated Jak2, PDGFR, Akt, and p42/p44 MAPK phosphorylation, which were attenuated by their respective inhibitors. Moreover, TNF-α stimulated Akt activation via a Jak2/PDGFR pathway in HPAEpiCs. In addition, TNF-α-induced p42/p44 MAPK phosphorylation was reduced by AG1296 or LY294002. On the other hand, TNF-α could induce Akt and p42/p44 MAPK translocation from the cytosol into the nucleus, which was inhibited by AG490, AG1296, or LY294002. Finally, we showed that TNF-α stimulated Elk-1 phosphorylation, which was reduced by LY294002 or PD98059. We also observed that TNF-α time dependently induced p300/Elk-1 and p300/Akt complex formation in HPAEpiCs, which was reduced by AG490, AG1296, or LY294002. The activity of cPLA2 protein upregulated by TNF-α was reflected on the PGE2 release, which was reduced by AG490, AG1296, LY294002, or PD98059. Taken together, these results demonstrated that TNF-α-induced cPLA2 expression and PGE2 release were mediated through a Jak2/PDGFR/PI3K/Akt/p42/p44 MAPK/Elk-1 pathway in HPAEpiCs.
Dept. of Pharmacology, Chang Gung Univ., College of Medicine, 259 Wen-Hwa 1st Road, Kwei-San, Tao-Yuan, Taiwan. chuenmao@mail.cgu.edu.tw).
Chuen-Mao
CM
Yang
I-Ta
IT
Lee
Pei-Ling
PL
Chi
Shin-Ei
SE
Cheng
Li-Der
LD
Hsiao
Chih-Kai
CK
Hsu
D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D002460:Cell Line; D002867:Chromones / Q000494:pharmacology; D015232:Dinoprostone / Q000378:metabolism*; D050881:E1A-Associated p300 Protein / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D053614:Janus Kinase 2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D008168:Lung / Q000378:metabolism / Q000473:pathology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics; D009025:Morpholines / Q000494:pharmacology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D054467:Phospholipases A2 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000235:genetics; D011014:Pneumonia / Q000473:pathology*; D011401:Promoter Regions, Genetic; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D017479:Receptors, Platelet-Derived Growth Factor / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D020032:Tyrphostins / Q000494:pharmacology; D050807:ets-Domain Protein Elk-1 / Q000378:metabolism
D002867:Chromones; D004791:Enzyme Inhibitors; D005419:Flavonoids; D009025:Morpholines; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D020032:Tyrphostins; C095512:alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide; D050807:ets-Domain Protein Elk-1; C106250:6,7-dimethoxy-3-phenylquinoxaline; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D050881:E1A-Associated p300 Protein; C494360:EP300 protein, human; D017479:Receptors, Platelet-Derived Growth Factor; C507924:JAK2 protein, human; D053614:Janus Kinase 2; D051057:Proto-Oncogene Proteins c-akt; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D054467:Phospholipases A2; D015232:Dinoprostone; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one
Elk-1; cytokine; cytosolic phospholipase A2; lung inflammation; signaling pathway