Sphingosine 1-phosphate-related metabolism in the blood vessel
Sphingosine 1-phosphate-related metabolism in the blood vessel
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DOI：
10.1093/jb/mvi100
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发表时间：
2005-07-01
影响因子：
2.7
通讯作者：
Ozaki, Y
中科院分区：
文献类型：
--
作者：
Aoki, S;Yatomi, Y;Ozaki, Y
1-磷酸鞘氨醇(sph-1-P)是一种从活化的血小板中释放出来的生物活性脂质，在血管生物学中发挥着重要作用。在本研究中，我们主要使用放射性标记的SPH和SPH-1-P来研究SPH-1-P在血管中的相关代谢。SPH在血浆中代谢稳定，而在活化的血小板存在下可转化为SPH-1-P。当SPH-1-P和血浆的混合物在凝胶过滤柱上分离时，所有的SPH-1-P都被琼脂糖凝胶电泳法与与脂蛋白和白蛋白一致的蛋白质组分共洗脱。经聚丙烯酰胺凝胶电泳法测定，加入血浆的SPH-1-P的放射性回收率分别为7.2+/-3.8%、53.3+/-6.4%和39.5+/-7.9%，分别来自低密度脂蛋白、高密度脂蛋白和白蛋白。另一方面，从胶原刺激的血小板中转化为Sph-1-P并释放到血浆中的Sph-1-P的放射性分别在低密度脂蛋白、高密度脂蛋白和白蛋白部分被回收5.2+/-3.2%、38.4+/-5.5%和56.3+/-5.7%。当检测激活的血小板释放Sph-1-P时，白蛋白的反应比脂蛋白更强，这表明白蛋白可以有效地从血小板中提取Sph-1-P。最后，在血浆中稳定的Sph-1-P在血管内皮细胞存在或在全血中被外磷酸酶活性显著降解。虽然SPH-1-P在血浆中是稳定的，但这种生物活性脂质的水平可能受到各种因素的动态控制，包括血小板释放、血浆蛋白分布和外磷酸酶的降解。
Sphingosine 1-phosphate (Sph-1-P) is a bioactive lipid released from activated platelets and plays an important role in vascular biology. In this study, we investigated Sph-1-P-related metabolism in the blood vessel, mainly using radio-labeled Sph and Sph-1-P. Sph was metabolically stable in the plasma, while it was converted into Sph-1-P in the presence of activated platelets. When the mixture of Sph-1-P and plasma was fractionated on a gel-filtration column, all Sph-1-P co-eluted with protein fractions that coincide with lipoproteins and albumin by agarose gel electrophoresis. When evaluated by polyacrylamide gel electrophoresis, 7.2 +/- 3.8%, 53.3 +/- 6.4%, and 39.5 +/- 7.9% of the radioactivity of Sph-1-P added to plasma was recovered in the low-density lipoprotein (LDL), high-density lipoprotein (HDL), and albumin fractions, respectively. On the other hand, 5.2 +/- 3.2%, 38.4 +/- 5.5%, and 56.3 +/- 5.7% of the radioactivity of Sph-1-P converted from Sph in collagen-stimulated platelets and released into the plasma was recovered in the LDL, HDL, and albumin fractions, respectively. When Sph-1-P release from activated platelets was examined, a stronger response was observed in the presence of albumin than lipoproteins, suggesting efficient Sph-1-P extraction from platelets by albumin. Finally, Sph-1-P, which is stable in the plasma, was markedly degraded by an ectophosphatase activity in the presence of vascular endothelial cells or in whole blood. Although Sph-1-P is stable in the plasma, it is likely that the level of this bioactive lipid is dynamically controlled by various factors including release from platelets, distribution among plasma proteins, and degradation by ectophosphatase.