Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Phospholipase A(2) (PLA(2))-activating protein (PLAA) is a novel signaling molecule that regulates the production of prostaglandins (PGE(2)) and tumor necrosis factor (TNF)-alpha. To characterize the function of native PLAA in situ, we generated HeLa (Tet-off) cells overexpressing plaa (plaa(high)) and control (plaa(low)) cells, with the plaa gene in opposite orientation in the latter construct. The plaa(high) cells produced significantly more PGE(2) and interleukin (IL)-6 compared to plaa(low) cells in response to TNF-alpha. There was an increased activation and/or expression of cytosolic PLA(2), cyclooxgenase-2, and NF-kappaB after induction of plaa(high) cells with TNF-alpha compared to the respective plaa(low) cells. Microarray analysis of plaa(high) cells followed by functional assays revealed increased production of proinflammatory cytokine IL-32 and a decrease in the production of annexin A4 and clusterin compared to plaa(low) cells. We demonstrated the role of annexin A4 as an inhibitor of PLA(2) and showed that addition of exogeneous clusterin limited the production of PGE(2) from plaa(high) cells. To understand regulation of plaa gene expression, we used a luciferase reporter system in HeLa cells and identified one stimulatory element, with Sp1 binding sites, and one inhibitory element, in exon 1 of the plaa gene. By using decoy DNA oligonucleotides to Sp1 and competitive binding assays, we showed that Sp1 maintains basal expression of the plaa gene and binds to the above-mentioned stimulatory element. We demonstrated for the first time that the induction of native PLAA by TNF-alpha can perpetuate inflammation by enhancing activation of PLA(2) and NF-kappaB.
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PMID:Alteration in the activation state of new inflammation-associated targets by phospholipase A2-activating protein (PLAA). 1829 23

Phospholipase A(2) (PLA(2))-activating protein (PLAA) is a novel signaling molecule that regulates eicosanoid production and participates in inflammatory responses. In our current study, we revealed that PLAA production was induced by the chemotherapeutic drug cisplatin in HeLa cervical carcinoma cells. To determine the potential pro-apoptotic effects of PLAA induction by cisplatin, we utilized HeLa (Tet-off) cells overexpressing the plaa gene (plaa(high)) and compared them with control (plaa(low)) cells, which produce endogenous plaa from the chromosome. Cisplatin-stimulated plaa(high) cells contained significantly higher levels of DNA fragmentation, caspase 3, 8 and 9 activities, PLA(2) enzyme activity, and cytochrome c leakage from mitochondria than did the cisplatin-stimulated plaa(low) cells. Importantly, siRNA against PLAA (siRNA-PLAA) reduced the levels of cisplatin-induced PLAA, DNA fragmentation, and PLA(2) activation, while promoting cell viability in both plaa(high) and plaa(low) cells. Cisplatin-induced-cytochrome c leakage in plaa(high) cells was reduced by siRNA-PLAA and restored by the addition of exogenous arachidonic acid (AA), suggesting to us that PLAA induction by cisplatin promoted cytochrome c leakage/mitochondrial damage partially by accumulating AA. In addition, cisplatin-stimulated plaa(high) cells produced less cytoprotective clusterin than did the cisplatin-stimulated plaa(low) cells, and siRNA-PLAA promoted clusterin production from both plaa(high) and plaa(low) cells. We showed that clusterin reduced DNA fragmentation in cisplatin-stimulated plaa(high) and plaa(low) cells, which is consistent with the notion that clusterin promotes cancer chemoresistance. Furthermore, cisplatin-stimulated plaa(high) cells produced more IL-32 (a pro-apoptotic protein) than did cisplatin-stimulated plaa(low) cells, and siRNA-PLAA reduced IL-32 production from both plaa(high) and plaa(low) cells. Finally, our proteomic analysis revealed that cisplatin-stimulated plaa(high) cells contained higher levels of phosphorylated JNK/c-Jun and FasL than did plaa(low) cells treated the same way. In summary, our data indicated that PLAA induction enhanced cisplatin-induced-apoptosis through four pathways, namely by: 1) accumulation of AA and mitochondrial damage, 2) downregulation of the cytoprotective clusterin, 3) upregulation of the pro-apoptotic IL-32, and 4) induction of JNK/c-Jun signaling and FasL expression.
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PMID:Phospholipase A2-activating protein (PLAA) enhances cisplatin-induced apoptosis in HeLa cells. 1925 36