title: A catalytically-inactive snake venom Lys49 phospholipase A₂ homolog induces expression of cyclooxygenase-2 and production of prostaglandins through selected signaling pathways in macrophages.
abstract: The effects of a snake venom Lys-49 phospholipase A2 (PLA2) homolog named MT-II, devoid of enzymatic activity, on the biosynthesis of prostaglandins and protein expression of cyclooxygenase-2 (COX-2) and signaling pathways involved were evaluated in mouse macrophages in culture and in peritoneal cells ex vivo. Stimulation of macrophages with MT-II leads to production of prostaglandin D2 (PGD2) and prostaglandin E2 (PGE2) and protein expression of COX-2 and microsomal prostaglandin E synthase-1 (mPGES-1). Inhibition of cytosolic PLA2 (cPLA2), but not Ca(2+) independent PLA2 (iPLA2) reduced release of PGD2 and PGE2 and expression of COX-2 induced by MT-II. Inhibition of nuclear factor κB (NF-κB) significantly reduced MT-II-induced PGE2, but not PGD2 production and COX-2 expression. Inhibitors of either protein kinase C (PKC), protein tyrosine kinase (PTK), or extracellular signal-regulated kinase (ERK) pathways abrogated MT-II-induced NF-κB activation and reduced COX-2 expression and PGE2 release, whereas the p38 mitogen-activated protein kinase (MAPK) inhibitor reduced MT-II-induced COX-2 expression and PGD2 production. Inhibition of phosphatidylinositol-3-kinase (PI3K) pathway abrogated MT-II-induced NF-κB activation, but affected neither prostaglandins production nor COX-2 expression. MT-II-induced production of PGD2 and PGE2 and COX-2 expression were also observed in vivo after intraperitoneal injection into mice. Collectively, our data demonstrate that a catalytically-inactive PLA2 homolog is capable of inducing prostaglandins biosynthesis and COX-2 expression in macrophages in both in vitro and in vivo models, indicating that the enzymatic activity of PLA2 is not necessary to trigger these effects. MT-II-activated NF-κB, cPLA2 and distinct protein kinases are the principal steps involved in these cellular events.
authors: Laboratório de Farmacologia, Instituto Butantan, Sao Paulo, Brazil.
authors: Vanessa
authors: V
authors: Moreira
authors: Pollyana Cristina Maggio
authors: PC
authors: de Castro Souto
authors: Marco Aurélio
authors: MA
authors: Ramirez Vinolo
authors: Bruno
authors: B
authors: Lomonte
authors: José
authors: J
authors: María Gutiérrez
authors: Rui
authors: R
authors: Curi
authors: Catarina
authors: C
authors: Teixeira
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003435:Crotalid Venoms; D051546:Cyclooxygenase 2 / Q000096:biosynthesis*; D015232:Dinoprostone / Q000378:metabolism; D054501:Group II Phospholipases A2 / Q000494:pharmacology*; D017737:Macrophages, Peritoneal / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D054512:Phospholipases A2, Calcium-Independent / Q000378:metabolism; D054510:Phospholipases A2, Cytosolic / Q000378:metabolism; D015230:Prostaglandin D2 / Q000378:metabolism; D011453:Prostaglandins / Q000096:biosynthesis*; D011493:Protein Kinase C / Q000378:metabolism; D030162:Reptilian Proteins / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D003435:Crotalid Venoms; D016328:NF-kappa B; D011453:Prostaglandins; D030162:Reptilian Proteins; C077623:Ptgs2 protein, mouse; D051546:Cyclooxygenase 2; D019869:Phosphatidylinositol 3-Kinases; D011493:Protein Kinase C; D048051:p38 Mitogen-Activated Protein Kinases; D054501:Group II Phospholipases A2; D054512:Phospholipases A2, Calcium-Independent; D054510:Phospholipases A2, Cytosolic; C061056:myotoxin II, Bothrops asper; D015232:Dinoprostone; D015230:Prostaglandin D2