Sphingosine 1-phosphate is released from the cytosol of rat platelets in a carrier-mediated manner
Sphingosine 1-phosphate is released from the cytosol of rat platelets in a carrier-mediated manner
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DOI：
10.1194/jlr.m500468-jlr200
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发表时间：
2006-03-01
影响因子：
6.5
通讯作者：
Yamaguchi, A
中科院分区：
文献类型：
--
作者：
Kobayashi, N;Nishi, T;Yamaguchi, A
鞘氨醇1-磷酸（S1P）在血小板中积累，并在凝血酶或Ca2+的刺激下释放。凝血酶刺激的S1P释放被staurosporin抑制，而Ca2+刺激的释放不受抑制。当溶链素O （SLO）渗透血小板质膜时，S1P随胞浆标记物渗出，而颗粒标记物留在血小板中。S1P泄漏需要BSA，可能是为了在介质中溶解S1P。这些结果表明，S1P定位于质膜内小叶，其释放是一个载体介导的过程。我们还使用了α -毒素（ATX），它在质膜上形成比SLO更小的孔，并且在没有bsa依赖的S1P泄漏的情况下消耗胞质ATP。ATP的加入促使ATX血小板释放S1P。凝血酶极大地增强了ATX血小板中atp驱动的S1P释放。ATP结合盒转运蛋白抑制剂格列本脲可阻止ATP和凝血酶诱导的S1P从血小板释放。Ca2+也刺激无ATP的ATX血小板释放S1P，而Ca2+诱导的释放不受格列本脲的抑制。我们的研究结果表明，血小板质膜中可能存在两种独立的S1P释放系统，即凝血酶刺激的atp依赖系统和Ca2+刺激的atp独立系统。
Sphingosine 1-phosphate (S1P) is accumulated in platelets and released on stimulation by thrombin or Ca2+. Thrombin-stimulated S1P release was inhibited by staurosporin, whereas Ca2+-stimulated release was not. When the platelet plasma membrane was permeabilized with streptolysin O (SLO), S1P leaked out with cytosol markers, whereas granular markers remained in the platelets. The SLO-induced S1P leakage required BSA, probably for solubilization of S1P in the medium. These results indicate that S1P is localized in the inner leaflet of the plasma membrane and that its release is a carrier-mediated process. We also used alpha-toxin (ATX), which makes smaller pores in the plasma membrane than SLO and depletes cytosolic ATP without BSA-dependent S1P leakage. The addition of ATP drove S1P release from ATX platelets. The ATP-driven S1P release from ATX platelets was greatly enhanced by thrombin. An ATP binding cassette transporter inhibitor, glyburide, prevents ATP-and thrombin-induced S1P release from platelets. Ca2+ also stimulated S1P release from ATX platelets without ATP, whereas the Ca2+-induced release was not inhibited by glyburide. Our results indicate that two independent S1P release systems might exist in the platelet plasma membrane, an ATP-dependent system stimulated by thrombin and an ATP-independent system stimulated by Ca2+.