title: Proinflammatory gene induction by platelet-activating factor mediated via its cognate nuclear receptor.
abstract: It has been postulated that intracellular binding sites for platelet-activating factor (PAF) contribute to proinflammatory responses to PAF. Isolated nuclei from porcine cerebral microvascular endothelial cells (PCECs) produced PAF-molecular species in response to H(2)O(2). Using FACS analysis, we demonstrated the expression of PAF receptors on cell and nuclear surfaces of PCECs. Confocal microscopy studies performed on PCECs, Chinese hamster ovary cells stably overexpressing PAF receptors, and isolated nuclei from PCECs also showed a robust nuclear distribution of PAF receptors. Presence of PAF receptors at the cell nucleus was further revealed in brain endothelial cells by radioligand binding experiments, immunoblotting, and in situ in brain by immunoelectron microscopy. Stimulation of nuclei with methylcarbamate-PAF evoked a decrease in cAMP production and a pertussis toxin-sensitive rise in nuclear calcium, unlike observations in plasma membrane, which exhibited a pertussis toxin-insensitive elevation in inositol phosphates. Moreover, on isolated nuclei methylcarbamate-PAF evoked the expression of proinflammatory genes inducible nitric oxide synthase and cyclooxygenase-2 (COX-2) and was associated with augmented extracellular signal-regulated kinase 1/2 phosphorylation and NF-kappaB binding to the DNA consensus sequence. COX-2 expression was prevented by mitogen-activated protein kinase kinase/extracellular signal-regulated kinase 1/2 and NF-kappaB inhibitors. This study describes for the first time the nucleus as a putative organelle capable of generating PAF and expresses its receptor, which upon stimulation induces the expression of the proinflammatory gene COX-2.
authors.affiliation: Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada.
authors.forename: A Marilise
authors.initials: AM
authors.lastname: Marrache
authors.forename: Fernand
authors.initials: F
authors.lastname: Gobeil
authors.forename: Sylvie G
authors.initials: SG
authors.lastname: Bernier
authors.forename: Jana
authors.initials: J
authors.lastname: Stankova
authors.forename: Marek
authors.initials: M
authors.lastname: Rola-Pleszczynski
authors.forename: Sanaa
authors.initials: S
authors.lastname: Choufani
authors.forename: Ghassan
authors.initials: G
authors.lastname: Bkaily
authors.forename: Annie
authors.initials: A
authors.lastname: Bourdeau
authors.forename: Martin G
authors.initials: MG
authors.lastname: Sirois
authors.forename: Alejandro
authors.initials: A
authors.lastname: Vazquez-Tello
authors.forename: Li
authors.initials: L
authors.lastname: Fan
authors.forename: Jean-Sébastien
authors.initials: JS
authors.lastname: Joyal
authors.forename: Janos G
authors.initials: JG
authors.lastname: Filep
authors.forename: Daya R
authors.initials: DR
authors.lastname: Varma
authors.forename: Alfredo
authors.initials: A
authors.lastname: Ribeiro-Da-Silva
authors.forename: Sylvain
authors.initials: S
authors.lastname: Chemtob
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000235:genetics; D016466:CHO Cells; D002467:Cell Nucleus / Q000378:metabolism / Q000648:ultrastructure; D002478:Cells, Cultured; D016384:Consensus Sequence; D006224:Cricetinae; D051546:Cyclooxygenase 2; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004730:Endothelium, Vascular / Q000378:metabolism / Q000648:ultrastructure; D015971:Gene Expression Regulation, Enzymologic; D018836:Inflammation Mediators / Q000378:metabolism*; D007527:Isoenzymes / Q000235:genetics; D008854:Microscopy, Electron; D019001:Nitric Oxide Synthase / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D010972:Platelet Activating Factor / Q000378:metabolism*; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism*; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled; D015398:Signal Transduction; D013552:Swine; D015533:Transcriptional Activation
chemical_list: D018836:Inflammation Mediators; D007527:Isoenzymes; D010972:Platelet Activating Factor; D010980:Platelet Membrane Glycoproteins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; C039351:platelet activating factor receptor; D004247:DNA; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases