Caveolin-1 enhances tissue factor pathway inhibitor exposure and function on the cell surface
Caveolin-1 enhances tissue factor pathway inhibitor exposure and function on the cell surface
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DOI：
10.1074/jbc.m503333200
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发表时间：
2005-06-10
影响因子：
4.8
通讯作者：
Lupu, F
中科院分区：
文献类型：
--
作者：
Lupu, C;Hu, XH;Lupu, F
组织因子途径抑制剂 (TFPI) 通过形成 TF-FVIIa-FXa-TFPI 复合物来阻断组织因子-因子 VIIa (TF-FVIIa) 对因子 X 和 IX 的激活。大多数体内 TFPI 与内皮细胞 (EC) 中的小窝相关。这种关联的机制和小穴 TFPI 的抗凝作用尚不清楚。在这里，我们表明，293 细胞中小窝蛋白-1 (Cav-1) 的表达使 TFPI 保持暴露在质膜表面，降低 TFPI 的膜侧向迁移率，并增加 TFPI 依赖性的 TF-FVIIa 抑制。与小凹相关的 TFPI 支持四元复合体与小凹的共定位。为了研究这些观察结果对 EC 的意义，我们使用 RNA 干扰来消除 Cav-1 细胞。功能测定和荧光显微镜显示，在缺乏 Cav-1 的 EC 中，TFPI 的抑制特性减弱，这显然是由于四元复合物的组装缺陷所致。这些发现表明，小窝通过外在凝血途径调节细胞结合的 TFPI 对活性蛋白酶产生的抑制。
Tissue factor pathway inhibitor ( TFPI) blocks tissue factor-factor VIIa (TF-FVIIa) activation of factors X and IX through the formation of the TF-FVIIa-FXa-TFPI complex. Most TFPI in vivo associates with caveolae in endothelial cells (EC). The mechanism of this association and the anticoagulant role of caveolar TFPI are not yet known. Here we show that expression of caveolin-1 (Cav-1) in 293 cells keeps TFPI exposed on the plasmalemma surface, decreases the membrane lateral mobility of TFPI, and increases the TFPI-dependent inhibition of TF-FVIIa. Caveolae-associated TFPI supports the co-localization of the quaternary complex with caveolae. To investigate the significance of these observations for EC we used RNA interference to deplete the cells of Cav-1. Functional assays and fluorescence microscopy revealed that the inhibitory properties of TFPI were diminished in EC lacking Cav-1, apparently through deficient assembly of the quaternary complex. These findings demonstrate that caveolae regulate the inhibition by cell-bound TFPI of the active protease production by the extrinsic pathway of coagulation.