Gueguen Geneviéve, Granci Virginie, Rogalle Pierre, Briand-Mésange Fabienne, Wilson Michéle, Klaébé Alain, Tercé François, Chap Hugues, Salles Jean-Pierre, Simon Marie-Françoise, Gaits Frédérique
Institut fédératif de recherche Claude de Préval, INSERM U326, Phospholipides membranaires, Signalisation cellulaire et Lipoprotéines, Hôpital Purpan, 31059 Toulouse Cedex, France.
Biochem J. 2002 Dec 1;368(Pt 2):447-59. doi: 10.1042/BJ20020273.
A previous study demonstrated that cross-desensitization experiments performed with the lysophosphatidic acid (LPA) analogues (R)- and (S)-N-palmitoyl-norleucinol 1-phosphate (PNPAs) inhibited LPA-induced platelet aggregation without any stereospecificity. Here we report opposite biological effects of the two enantiomers on mitogenesis of IMR-90 fibroblasts in relation to their respective metabolism. (R)PNPA was proliferative, while (S)PNPA induced apoptosis by specifically inhibiting phosphatidylcholine biosynthesis at the last step of the CDP-choline pathway controlled by cholinephosphotransferase. This effect was not direct but required dephosphorylation of PNPAs by ecto-lipid phosphate phosphatase before cellular uptake of the generated N-palmitoyl-norleucinols (PNOHs). Inhibition of cholinephosphotransferase by the derivative (S)PNOH was confirmed by an in vitro assay. (S)PNPA proapoptotic effects led us to clarify the mechanism linking cholinephosphotransferase inhibition to apoptosis. Three proapoptotic responses were observed: the activation of caspase-3, the production of ceramides from newly synthesized pools (as demonstrated by the inhibitor Fumonisin B1) and finally the activation of stress-activated protein kinase, p38 and c-Jun N-terminal kinases 1/2, as a result of ceramide increase. Thus our data demonstrate that synthetic analogues of LPA might display stereospecific effects leading to apoptosis independently of classical LPA-activated pathways.
先前的一项研究表明，用溶血磷脂酸（LPA）类似物（R）-和（S）-N-棕榈酰-正亮氨醇1-磷酸酯（PNPAs）进行的交叉脱敏实验可抑制LPA诱导的血小板聚集，且无任何立体特异性。在此，我们报告了这两种对映体对IMR-90成纤维细胞有丝分裂的相反生物学效应及其各自的代谢情况。（R）PNPA具有增殖作用，而（S）PNPA通过特异性抑制由胆碱磷酸转移酶控制的CDP-胆碱途径最后一步的磷脂酰胆碱生物合成来诱导细胞凋亡。这种效应不是直接的，而是需要在细胞摄取生成的N-棕榈酰-正亮氨醇（PNOHs）之前，由胞外脂质磷酸磷酸酶将PNPAs去磷酸化。衍生物（S）PNOH对胆碱磷酸转移酶的抑制作用通过体外试验得到证实。（S）PNPA的促凋亡作用使我们阐明了胆碱磷酸转移酶抑制与细胞凋亡之间的机制联系。观察到三种促凋亡反应：caspase-3的激活、新合成池产生神经酰胺（如抑制剂伏马菌素B1所示）以及由于神经酰胺增加导致应激激活蛋白激酶p38和c-Jun N端激酶1/2的激活。因此，我们的数据表明，LPA的合成类似物可能表现出立体特异性效应，导致细胞凋亡，而与经典的LPA激活途径无关。
