Division of Molecular and Cellular Signaling, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan.
Division of Molecular and Cellular Signaling, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan.
J Biol Chem. 2014 Mar 7;289(10):6451-6461. doi: 10.1074/jbc.M113.529503. Epub 2014 Jan 22.
Vascular endothelial cells (ECs) are continuously exposed to shear stress (SS) generated by blood flow. Such stress plays a key role in regulation of various aspects of EC function including cell proliferation and motility as well as changes in cell morphology. Vascular endothelial-protein-tyrosine phosphatase (VE-PTP) is an R3-subtype PTP that possesses multiple fibronectin type III-like domains in its extracellular region and is expressed specifically in ECs. The role of VE-PTP in EC responses to SS has remained unknown, however. Here we show that VE-PTP is diffusely localized in ECs maintained under static culture conditions, whereas it undergoes rapid accumulation at the downstream edge of the cells relative to the direction of flow in response to SS. This redistribution of VE-PTP triggered by SS was found to require its extracellular and transmembrane regions and was promoted by integrin engagement of extracellular matrix ligands. Inhibition of actin polymerization or of Cdc42, Rab5, or Arf6 activities attenuated the SS-induced redistribution of VE-PTP. VE-PTP also underwent endocytosis in the static and SS conditions. SS induced the polarized distribution of internalized VE-PTP. Such an effect was promoted by integrin engagement of fibronectin but prevented by inhibition of Cdc42 activity or of actin polymerization. In addition, depletion of VE-PTP by RNA interference in human umbilical vein ECs blocked cell elongation in the direction of flow induced by SS. Our results suggest that the polarized redistribution of VE-PTP in response to SS plays an important role in the regulation of EC function by blood flow.
血管内皮细胞（ECs）持续暴露于血流产生的切变应力（SS）中。这种应激在调节 EC 功能的各个方面起着关键作用，包括细胞增殖和迁移以及细胞形态的变化。血管内皮蛋白酪氨酸磷酸酶（VE-PTP）是 R3 亚型 PTP，其细胞外区域具有多个纤维连接蛋白 III 样结构域，并且特异性表达于 ECs。然而，VE-PTP 在 EC 对 SS 的反应中的作用仍然未知。在这里，我们发现 VE-PTP 在静态培养条件下的 EC 中弥散定位，而在 SS 响应下，它在相对于流动方向的细胞下游边缘快速积累。发现 SS 触发的 VE-PTP 的这种重新分布需要其细胞外和跨膜区域，并且通过整合素与细胞外基质配体的结合而促进。肌动蛋白聚合或 Cdc42、Rab5 或 Arf6 活性的抑制减弱了 SS 诱导的 VE-PTP 重新分布。VE-PTP 在静态和 SS 条件下也经历内吞作用。SS 诱导内化的 VE-PTP 的极化分布。这种效应通过整合素与纤维连接蛋白的结合而促进，但通过抑制 Cdc42 活性或肌动蛋白聚合来阻止。此外，在人脐静脉 ECs 中通过 RNA 干扰耗尽 VE-PTP 阻断了 SS 诱导的沿流动方向的细胞伸长。我们的结果表明，VE-PTP 对 SS 的极化重新分布在血流调节 EC 功能中起着重要作用。
