tailieunhanh - Báo cáo khoa học: Calcium-independent phospholipase A2-mediated formation of 1,2-diarachidonoyl-glycerophosphoinositol in monocytes

Phagocytic cells exposed to exogenous arachidonic acid (AA) incorporate large quantities of this fatty acid into choline and ethanolamine glycero-phospholipids, and into phosphatidylinositol (PtdIns). Utilizing liquid chro-matography coupled to MS, we have characterized the incorporation of exogenous deuterated AA ([ 2 H]AA) into specific PtdIns molecular species in human monocyte cells. | ễFEBS Journal Calcium-independent phospholipase A2-mediated formation of 1 2-diarachidonoyl-glycerophosphoinositol in monocytes David Balgoma Olimpio Montero Maria A. Balboa and Jesus Balsinde Institute de Biología y Genetica Molecular Consejo Superior de Investigaciones Cientificas CSIC and Centro de Investigacion Biomedica en Red de Diabetes y Enfermedades Metabolicas Asociadas CIBERDEM Valladolid Spain Keywords arachidonic acid deacylation reactions glycerophospholipid synthesis Lands cycle lipid mediators Correspondence J. Balsinde Instituto de Biologia y Genetica Molecular Consejo Superior de Investigaciones Cientificas CSIC and Centro de Investigacion Biomedica en Red de Diabetes y Enfermedades Metabolicas Asociadas CIBERDEM 47003 Valladolid Spain Fax 34 983 423 588 Tel 34 983 423 062 E-mail jbalsinde@ Received 8 September 2008 revised 10 October 2008 accepted 14 October 2008 doi Phagocytic cells exposed to exogenous arachidonic acid AA incorporate large quantities of this fatty acid into choline and ethanolamine glycero-phospholipids and into phosphatidylinositol PtdIns . Utilizing liquid chromatography coupled to MS we have characterized the incorporation of exogenous deuterated AA 2H AA into specific PtdIns molecular species in human monocyte cells. A PtdIns species containing two exogenous 2H AA molecules 1- 2H AA-2- 2H AA-glycero-3-phosphoinositol was readily detected when human U937 monocyte-like cells and peripheral blood monocytes were exposed to 2H AA concentrations as low as 160 nM to 1 M. Bromoenol lactone an inhibitor of Ca2 -independent phospholipase A2 iPLA2 diminished lyso-PtdIns levels and almost completely inhibited the appearance of 1- 2H AA-2- 2H AA-glycero-3-phosphoinositol suggesting the involvement of deacylation reactions in the synthesis of this phospholipid. De novo synthesis did not appear to be involved as no other diarachidonoyl phospholipid or neutral lipid was detected under these .