Takeya Hiroyuki, Gabazza Esteban C, Aoki Shinya, Ueno Hikaru, Suzuki Koji
Department of Biochemistry, University of Occupational and Environmental Health, School of Medicine, Kitakyushu 807-8555, Japan.
Blood. 2003 Sep 1;102(5):1693-700. doi: 10.1182/blood-2002-11-3607. Epub 2003 May 1.
Sphingosine 1-phosphate (S1P), a bioactive lipid, is produced and stored in platelets and is released from activated platelets during blood coagulation activation. Thrombin, which is also generated during blood coagulation, has been shown to induce tissue factor (TF), the initiator of blood coagulation, in endothelial cells (ECs); however, the effect of S1P on this process is not evaluated. Here we demonstrated that S1P strongly potentiated thrombin-induced TF expression in ECs and that S1P itself did not induce TF expression. Among signaling lipids, platelet-activating factor slightly enhanced thrombin-induced TF expression; other lipids, including lysophosphatidic acid, lysophosphatidylcholine, sphingosine, and C2-ceramide exert no effect on TF expression. S1P enhanced TF expression at the transcriptional level, possibly via promoting the activation of transcription factors nuclear factor-kappaB (NF-kappaB) and Egr-1. Thrombin weakly and S1P strongly activated extracellular signal-regulated kinase 1/2 (ERK1/2) mitogen-activated protein (MAP) kinase and, in the presence of both stimulants, enhanced and sustained activation of this kinase was observed. The ERK1/2-specific inhibitor PD98059 significantly inhibited enhanced TF expression induced by both stimulants but only weakly inhibited thrombin-induced TF expression, thus indicating the requirement of the ERK1/2 pathway in synergistic induction of TF expression. In addition, we found that thrombin and S1P rapidly up-regulated the expression of S1P receptors, endothelial differentiation gene-1 (EDG-1) and EDG-3, thereby suggesting that the effect of S1P on TF expression and other EC functions may be enhanced by thrombin and S1P itself. The present data reveal the synergistic effect of S1P on thrombin-induced TF expression in ECs, which may promote further thrombin and S1P generation, thus propagating a positive feedback reaction.
鞘氨醇-1-磷酸（S1P）是一种生物活性脂质，在血小板中产生并储存，在凝血激活过程中从活化的血小板中释放出来。凝血过程中产生的凝血酶已被证明可在内皮细胞（ECs）中诱导组织因子（TF），即凝血的启动因子；然而，S1P对这一过程的影响尚未评估。在这里，我们证明S1P强烈增强了凝血酶诱导的ECs中TF的表达，而S1P本身不会诱导TF表达。在信号脂质中，血小板活化因子略微增强了凝血酶诱导的TF表达；其他脂质，包括溶血磷脂酸、溶血磷脂酰胆碱、鞘氨醇和C2-神经酰胺对TF表达没有影响。S1P可能通过促进转录因子核因子-κB（NF-κB）和早期生长反应因子-1（Egr-1）的激活，在转录水平上增强TF表达。凝血酶对细胞外信号调节激酶1/2（ERK1/2）丝裂原活化蛋白（MAP）激酶的激活作用较弱，而S1P的激活作用较强，并且在两种刺激物同时存在的情况下，观察到该激酶的激活增强并持续。ERK1/2特异性抑制剂PD98059显著抑制了两种刺激物诱导的TF表达增强，但仅微弱抑制凝血酶诱导的TF表达，因此表明ERK1/2途径在协同诱导TF表达中是必需的。此外，我们发现凝血酶和S1P迅速上调了S1P受体内皮分化基因-1（EDG-1）和EDG-3的表达，从而表明凝血酶和S1P本身可能会增强S1P对TF表达和其他EC功能的影响。目前的数据揭示了S1P对凝血酶诱导的ECs中TF表达的协同作用，这可能会促进进一步的凝血酶和S1P生成，从而引发正反馈反应。
