title: sPLA2-V inhibits EPCR anticoagulant and antiapoptotic properties by accommodating lysophosphatidylcholine or PAF in the hydrophobic groove.
abstract: The endothelial protein C receptor (EPCR) plays an important role in cardiovascular disease by binding protein C/activated protein C (APC). EPCR structure contains a hydrophobic groove filled with an unknown phospholipid needed to perform its function. It has not been established whether lipid exchange takes place in EPCR as a regulatory mechanism of its activity. Our objective was to identify this phospholipid and to explore the possibility of lipid exchange as a regulatory mechanism of EPCR activity driven by the endothelially expressed secretory group V phospholipase A(2) (sPLA(2)-V). We identified phosphatidylcholine (PCh) as the major phospholipid bound to human soluble EPCR (sEPCR). PCh in EPCR could be exchanged for lysophosphatidylcholine (lysoPCh) and platelet activating factor (PAF). Remarkably, lysoPCh and PAF impaired the protein C binding ability of sEPCR. Inhibition of sPLA(2)-V, responsible for lysoPCh and PAF generation, improved APC binding to endothelial cells. EPCR-dependent protein C activation and APC antiapoptotic effect were thus significantly enhanced. In contrast, endothelial cell supplementation with sPLA(2)-V inhibited both APC generation and its antiapoptotic effects. We conclude that APC generation and function can be modulated by changes in phospholipid occupancy of its endothelial cell receptor.
authors.affiliation: Division of Cardiovascular Sciences, Laboratory of Thrombosis and Haemostasis, Centre for Applied Medical Research, University of Navarra, Pamplona, Spain.
authors.forename: Jacinto
authors.initials: J
authors.lastname: López-Sagaseta
authors.forename: Cristina
authors.initials: C
authors.lastname: Puy
authors.forename: Ibai
authors.initials: I
authors.lastname: Tamayo
authors.forename: Mikel
authors.initials: M
authors.lastname: Allende
authors.forename: Jorge
authors.initials: J
authors.lastname: Cerveró
authors.forename: Susana E
authors.initials: SE
authors.lastname: Velasco
authors.forename: Charles T
authors.initials: CT
authors.lastname: Esmon
authors.forename: Ramón
authors.initials: R
authors.lastname: Montes
authors.forename: José
authors.initials: J
authors.lastname: Hermida
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000737:chemistry* / Q000378:metabolism*; D002855:Chromatography, Thin Layer; D042783:Endothelial Cells / Q000378:metabolism; D000074283:Endothelial Protein C Receptor; D004789:Enzyme Activation / Q000502:physiology; D005434:Flow Cytometry; D054505:Group V Phospholipases A2 / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D008244:Lysophosphatidylcholines / Q000737:chemistry* / Q000378:metabolism; D013058:Mass Spectrometry; D051379:Mice; D010972:Platelet Activating Factor / Q000737:chemistry* / Q000378:metabolism; D011486:Protein C / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
chemical_list: D015703:Antigens, CD; D000074283:Endothelial Protein C Receptor; D008244:Lysophosphatidylcholines; C478370:PROCR protein, human; D010972:Platelet Activating Factor; D011486:Protein C; D011956:Receptors, Cell Surface; D054505:Group V Phospholipases A2