Jalink K, Hengeveld T, Mulder S, Postma F R, Simon M F, Chap H, van der Marel G A, van Boom J H, van Blitterswijk W J, Moolenaar W H
Division of Cellular Biochemistry, The Netherlands Cancer Institute, Amsterdam.
Biochem J. 1995 Apr 15;307 ( Pt 2)(Pt 2):609-16. doi: 10.1042/bj3070609.
Lysophosphatidic acid (LPA; 1-acyl-sn-glycero-3-phosphate) is a platelet-derived lipid mediator that activates its own G-protein-coupled receptor to trigger phospholipase C-mediated Ca2+ mobilization and other effector pathways in numerous cell types. In this study we have examined the structural features of LPA that are important for activation of the Ca(2+)-mobilizing receptor in human A431 carcinoma cells, which show an EC50 for oleoyl-LPA as low as 0.2 nM. When the acyl chain at the sn-1 position is altered, the rank order of potency is oleoyl-LPA > arachidonoyl-LPA > linolenoyl-LPA > linoleoyl-LPA > stearoyl-LPA = palmitoyl-LPA > myristoyl-LPA. The shorter-chain species, lauroyl- and decanoyl-LPA, show little or no activity. Ether-linked LPA (1-O-hexadecyl-sn-glycero-3-phosphate) is somewhat less potent than the corresponding ester-linked LPA; its stereoisomer is about equally active. Deletion of the glycerol backbone causes a 1000-fold decrease in potency. Replacement of the phosphate group in palmitoyl-LPA by a hydrogen- or methyl-phosphonate moiety results in complete loss of activity. A phosphonate analogue with a methylene group replacing the oxygen at sn-3 has strongly decreased activity. All three phosphonate analogues induce cell lysis at doses > 15 microM. Similarly, the methyl and ethyl esters of palmitoyl-LPA are virtually inactive and become cytotoxic at micromolar doses. None of the LPA analogues tested has antagonist activity. Sphingosine 1-phosphate, a putative messenger with some structural similarities to LPA, elicits a transient rise in intracellular [Ca2+] only at micromolar doses; however, cross-desensitization experiments indicate that sphingosine 1-phosphate does not act through the LPA receptor. The results indicate that, although many features of the LPA structure are important for optimal activity, the phosphate group is most critical, suggesting that this moiety is directly involved in receptor activation.
溶血磷脂酸（LPA；1-酰基-sn-甘油-3-磷酸）是一种源自血小板的脂质介质，它激活自身的G蛋白偶联受体，从而在多种细胞类型中触发磷脂酶C介导的Ca2+动员及其他效应途径。在本研究中，我们检测了LPA的结构特征，这些特征对于激活人A431癌细胞中的Ca(2+)动员受体很重要，该受体对油酰-LPA的EC50低至0.2 nM。当sn-1位的酰基链发生改变时，效力的排序为：油酰-LPA > 花生四烯酰-LPA > 亚麻酸酰-LPA > 亚油酰-LPA > 硬脂酰-LPA = 棕榈酰-LPA > 肉豆蔻酰-LPA。较短链的月桂酰-LPA和癸酰-LPA几乎没有活性。醚键连接的LPA（1-O-十六烷基-sn-甘油-3-磷酸）的效力略低于相应的酯键连接的LPA；其立体异构体的活性大致相同。去除甘油主链会导致效力降低1000倍。用氢膦酸酯或甲基膦酸酯部分取代棕榈酰-LPA中的磷酸基团会导致活性完全丧失。在sn-3位用亚甲基取代氧的膦酸酯类似物活性大幅降低。所有三种膦酸酯类似物在剂量>15 microM时都会诱导细胞裂解。同样，棕榈酰-LPA的甲酯和乙酯实际上没有活性，在微摩尔剂量时具有细胞毒性。所测试的LPA类似物均无拮抗活性。鞘氨醇-1-磷酸是一种与LPA有一些结构相似性的假定信使，仅在微摩尔剂量时才会引起细胞内[Ca2+]的短暂升高；然而，交叉脱敏实验表明鞘氨醇-1-磷酸不是通过LPA受体起作用。结果表明，尽管LPA结构的许多特征对最佳活性很重要，但磷酸基团最为关键，这表明该部分直接参与受体激活。
