Thrombin activated human platelets acutely generate oxidized docosahexanoic acid-containing phospholipids via 12-lipoxygenase.

Lloyd Morgan , Christopher P Thomas , Hartmut Kuhn , V B O'Donnell (1)

1 Dept of Medical Biochemistry and Immunology

AArachidonate-containing oxidized phospholipids are acutely generated by 12-lipoxygenase (LOX) in agonist-activated platelets. In this study, formation of structurally-related lipids by oxidation of docosahexanoic acid (DHA)-containing phospholipids is demonstrated using lipidomic approaches. Precursor scanning reverse phase LC/MS/MS identified a new family of lipids that comprise phospholipid-esterified hydroxydocosahexanoic acid (HDOHE). Two diacyl and two plasmalogen phosphatidylethanolamines containing predominantly the 14-HDOHE positional isomer (18:0p/14-HDOHE-PE, 18:0a/14-HDOHE-PE, 16:0a/14-HDOHE-PE, 16:0p/14-HDOHE-PE) were structurally characterized using MS/MS and by comparison with biogenic standards. An involvement of 12-LOX was indicated since purified recombinant human 12-LOX also generated the 14-HDOHE isomer from DHA. Pharmacological studies using inhibitors and recombinant platelet 12-LOX indicate that they form via esterification of newly formed free HDOHE. HDOHE-PEs formed at significant rates (2 - 4 ng/4 x 107 cells) within 2 - 180 min of thrombin stimulation, and their formation was blocked by calcium chelation. In summary, a new family of oxidized phospholipid was identified in thrombin-activated human platelets.

Mots clés: Life Sciences

Lloyd Morgan, Christopher P Thomas, Hartmut Kuhn, V B O'Donnell. Thrombin activated human platelets acutely generate oxidized docosahexanoic acid-containing phospholipids via 12-lipoxygenase.. Biochemical Journal, 2010, 431 (1), pp.141-148. ⟨10.1042/BJ20100415⟩. ⟨hal-00517250⟩