Kuksis Arnis, Pruzanski Waldemar
Banting and Best Department of Medical Research, Charles H. Best Institute, University of Toronto, 112 College Street, Toronto, ON, M5G 1L6, Canada.
Department of Medicine, University of Toronto, Toronto, Canada.
Lipids. 2017 Jun;52(6):477-488. doi: 10.1007/s11745-017-4264-z. Epub 2017 May 20.
Biologically active F- and E/D-type-prostane ring isomers (F-IP and E/D-IP, respectively) are produced in situ by non-enzymatic peroxidation of arachidonic acid esterified to GroPCho (PtdCho-IP) and are universally distributed in tissue lipoproteins and cell membranes. Previous work has shown that platelet-activating factor acetylhydrolases (PAF-AH) are the main endogenous PLA involved in degradation of PtdCho-IP. The present study shows that the PtdCho-IP are also subject to hydrolysis by group IIA, V and X secretory PLA, which also have a wide peripheral tissue distribution. For this demonstration, we compared the LC/MS profiles of PtdCho-IP of auto-oxidized plasma lipoproteins after incubation for 1-4 h (37 °C) in the absence or presence of recombinant human sPLA (1-2.5 µg/ml). In the absence of exogenously added sPLA the total PtdCho-IP level after 4 h incubation reached 15.9, 21.6 and 8.7 nmol/mg protein of LDL, HDL and HDL, respectively. In the presence of group V or group X sPLA (2.5 µg/ml), the PtdCho-IP was completely hydrolyzed in 1 h, while in the presence of group IIA sPLA (2.5 µg/ml) the hydrolysis was less than 25% in 4 h, although it was complete after 8-24 h incubation. This report provides the first demonstration that PtdCho-IP are readily hydrolyzed by group IIA, V and X sPLA. A co-location of sPLA and the substrates in various tissues has been recorded. Thus, the initiation of interaction and production of isoprostanes in situ are highly probable.
生物活性F型和E/D型前列腺素环异构体（分别为F-IP和E/D-IP）通过花生四烯酸与甘油磷酰胆碱（磷脂酰胆碱-IP）酯化后的非酶促过氧化原位生成，并普遍分布于组织脂蛋白和细胞膜中。先前的研究表明，血小板活化因子乙酰水解酶（PAF-AH）是参与磷脂酰胆碱-IP降解的主要内源性磷脂酶A。本研究表明，磷脂酰胆碱-IP也可被IIA、V和X组分泌型磷脂酶A水解，这些酶在周围组织中也广泛分布。为了证明这一点，我们比较了在不存在或存在重组人分泌型磷脂酶A（1-2.5μg/ml）的情况下，自氧化血浆脂蛋白的磷脂酰胆碱-IP在37℃孵育1-4小时后的液相色谱/质谱图谱。在没有外源添加分泌型磷脂酶A的情况下，孵育4小时后，低密度脂蛋白、高密度脂蛋白和高密度脂蛋白的总磷脂酰胆碱-IP水平分别达到15.9、21.6和8.7nmol/mg蛋白质。在存在V组或X组分泌型磷脂酶A（2.5μg/ml）的情况下，磷脂酰胆碱-IP在1小时内完全水解，而在存在IIA组分泌型磷脂酶A（2.5μg/ml）的情况下，4小时内水解率不到25%，尽管在孵育8-24小时后水解完全。本报告首次证明磷脂酰胆碱-IP很容易被IIA、V和X组分泌型磷脂酶A水解。已记录到分泌型磷脂酶A与底物在各种组织中的共定位。因此，原位相互作用的启动和异前列腺素的产生极有可能。
