ldentifcation of the secretion mechanism of lipid mediators from the cells

鉴定细胞脂质介质的分泌机制

基本信息

批准号：
18570128
负责人：
NISHI Tsuyoshi
金额：
$ 2.63万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

Intercellular signal transduction is the important system for the cell-cell communication in the highly organized living organism. Lipophilic compounds such as steroid hormones and lipid mediators are one of the most popular signaling molecules. However, little is known about how are these molecules exported from the cells. We are trying to identify the secretion mechanism and to isolate the transporters that are directly transporting these lipophific molecules. For this purpose, we are focusing to identify the sphingosine-1-phosphate (S1P) secretion system from the platelet. S1P is the lipid mediators that are playing important roles in cell migration, proliferation and apoptosis. So far, we were identified that S1 P is located in the inner leaflet of the plasma membrane and is showed thrombin or Ca^<2+> dependent secretion from the platelet. Using the transporter specific inhibitors, we proposed that ABC A-type transporters might participate the export of sphingosine-1-phosphate. Among the ABCA type transporters, we showed that ABCA7 is predominantly expressed in platelet. These results suggested that ABCA7 should be a candidate of sphingosine-1-phosphate transporter. To prove this hypothesis, we have been constructing the ABCA7 knock-out mice. We also identified that erythrocyte is synthesized the S1P and S1P is secreted from the cell without any stimuli. We prepared the inside-out membrane vesicle from rat erythrocyte and success to measure the S1 P transport activity. This S1P transport was ATP dependent manner and inhibited with glyburide and vanadate but not with other inhibitors for transporters or ionophores. These results strongly suggested the presence of transporter mediated S1P export system in rat erythrocyte.

细胞间信号转导是高度有组织的生物体中细胞 - 细胞通信的重要系统。亲脂化合物，例如类固醇激素和脂质介质是最流行的信号分子之一。但是，这些分子是如何从细胞中导出的。我们正在尝试识别分泌机制，并隔离直接运输这些亲亲分子的转运蛋白。为此，我们集中精力确定血小板中的鞘氨醇-1-磷酸盐（S1P）分泌系统。 S1P是在细胞迁移，增殖和凋亡中起重要作用的脂质介质。到目前为止，我们已经确定S1 P位于质膜的内部小叶中，并显示出血小板的凝血酶或Ca^<2+>依赖性分泌。使用转运蛋白特异性抑制剂，我们提出ABC A型转运蛋白可能参与鞘氨酸-1-磷酸盐的出口。在ABCA型转运蛋白中，我们表明ABCA7主要在血小板中表达。这些结果表明，ABCA7应该是鞘氨醇1-磷酸转运蛋白的候选者。为了证明这一假设，我们一直在构建ABCA7敲除小鼠。我们还确定了红细胞合成的，S1P和S1P在没有任何刺激的情况下分泌。我们从大鼠红细胞和成功中制备了内而外的膜囊泡，以测量S1 P转运活性。这种S1P转运是ATP依赖性的，并用Glyburide和vanadate抑制，但没有用于转运蛋白或离子载体的其他抑制剂。这些结果强烈建议在大鼠红细胞中存在转运蛋白介导的S1P输出系统。