title: GVI phospholipase A2 role in the stimulatory effect of sphingosine-1-phosphate on TRPC5 cationic channels.
abstract: The Transient Receptor Potential Canonical 5 (TRPC5) protein forms calcium-permeable cationic channels that are stimulated by G protein-coupled receptor agonists. The signaling pathways of such agonist effects are poorly understood. Here we investigated the potential for involvement of lysophosphatidylcholine (LPC) and arachidonic acid generated by group 6 (GVI) phospholipase A2 (PLA2) enzymes, focusing on stimulation of TRPC5 by sphingosine-1-phosphate (S1P) which acts via a pertussis toxin-sensitive (Gi/o protein) pathway without Ca2+-release. Experiments were on HEK 293 cells containing conditional expression of human TRPC5. Channel activity was recorded using an intracellular calcium indicator or whole-cell patch-clamp and PLA2 activity was detected using 3H-arachidonic acid. S1P stimulated PLA2 and TRPC5 activities. Both effects were suppressed by the GVI PLA2 inhibitor bromoenol lactone. Knock-down of GVI PLA2 by RNA interference suppressed channel activity evoked by S1P whereas activity evoked by the direct channel stimulator LPC was unaffected. Arachidonic acid did not stimulate the channels. Prior exposure of channels to LPC but not arachidonic acid suppressed channel activity evoked by S1P but not gadolinium, a putative direct stimulator of the channels. The data suggest roles of LPC and GVI PLA2 in S1P-evoked TRPC5 activity.
authors: Multidisciplinary Cardiovascular Research Centre and the Institute of Membrane & Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
authors: Eman
authors: E
authors: AL-Shawaf
authors: Sarka
authors: S
authors: Tumova
authors: Jacqueline
authors: J
authors: Naylor
authors: Yasser
authors: Y
authors: Majeed
authors: Jing
authors: J
authors: Li
authors: David J
authors: DJ
authors: Beech
mesh_terms: D000200:Action Potentials; D016718:Arachidonic Acid / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D020868:Gene Silencing; D057809:HEK293 Cells; D006801:Humans; D008244:Lysophosphatidylcholines / Q000378:metabolism*; D008246:Lysophospholipids / Q000494:pharmacology*; D009281:Naphthalenes / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D037342:Pertussis Toxin / Q000494:pharmacology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D064801:Phospholipase A2 Inhibitors; D054467:Phospholipases A2 / Q000378:metabolism; D010957:Plasmids; D011753:Pyrones / Q000494:pharmacology; D034741:RNA, Small Interfering; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D050052:TRPC Cation Channels / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D014316:Tritium / Q000032:analysis
chemical_list: D008244:Lysophosphatidylcholines; D008246:Lysophospholipids; D009281:Naphthalenes; D010726:Phosphodiesterase Inhibitors; D064801:Phospholipase A2 Inhibitors; D011753:Pyrones; D034741:RNA, Small Interfering; D050052:TRPC Cation Channels; C491780:TRPC5 protein, human; D014316:Tritium; C060506:sphingosine 1-phosphate; D016718:Arachidonic Acid; C068314:6-(bromomethylene)tetrahydro-3-(1-naphthaleneyl)-2H-pyran-2-one; D037342:Pertussis Toxin; D054467:Phospholipases A2; D013110:Sphingosine; D002118:Calcium