1Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University, No. 1, University Rd., Tainan 701, Taiwan. H.-L.W.,
FASEB J. 2013 Nov;27(11):4520-31. doi: 10.1096/fj.13-227561. Epub 2013 Aug 13.
Urokinase-type plasminogen activator (uPA) activates plasminogen (Plg) through a major pericellular proteolytic system involved in cell migration and angiogenesis; however, the Plg receptor that participates in uPA-mediated Plg activation has not yet been identified. In this study, we demonstrated that thrombomodulin (TM), a type I transmembrane glycoprotein, is a novel Plg receptor that plays a role in pericellular proteolysis and cell migration. Plg activation at the cell surface and the extent of its cell migration- and invasion-promoting effect are cellular TM expression dependent. Direct binding of Plg and the recombinant TM extracellular domain, with a KD of 0.1-0.3 μM, was determined through surface plasmon resonance analysis. Colocalization of TM, Plg, and the uPA receptor within plasma membrane lipid rafts, at the leading edge of migrating endothelial cells, was demonstrated and was also shown to overlap with areas of major pericellular proteolysis. Moreover, the roles of TM and Plg in neoangiogenesis were demonstrated in vivo through the skin wound-healing model. In conclusion, we propose that TM is a novel Plg receptor that regulates uPA/uPA receptor-mediated Plg activation and pericellular proteolysis within lipid rafts at the leading edge of migrating cells during angiogenesis.
尿激酶型纤溶酶原激活物 (uPA) 通过参与细胞迁移和血管生成的主要细胞周蛋白水解系统激活纤溶酶原 (Plg)；然而，参与 uPA 介导的 Plg 激活的 Plg 受体尚未被鉴定。在这项研究中，我们证明了血栓调节蛋白 (TM)，一种 I 型跨膜糖蛋白，是一种新型的 Plg 受体，在细胞周蛋白水解和细胞迁移中发挥作用。细胞表面的 Plg 激活及其促进细胞迁移和侵袭的程度依赖于细胞 TM 表达。通过表面等离子体共振分析确定了 Plg 与重组 TM 细胞外结构域之间的直接结合，KD 值为 0.1-0.3 μM。在迁移内皮细胞前缘的质膜脂筏内，TM、Plg 和 uPA 受体的共定位被证明，并且与主要细胞周蛋白水解区域重叠。此外，通过皮肤创伤愈合模型在体内证明了 TM 和 Plg 在新血管生成中的作用。总之，我们提出 TM 是一种新型的 Plg 受体，可调节 uPA/uPA 受体介导的 Plg 激活和血管生成过程中迁移细胞前缘脂筏内的细胞周蛋白水解。
