Department of Pediatrics and Developmental Vascular Biology Program, Medical College of Wisconsin and Children's Research Institute, Milwaukee, Wisconsin 53226, USA.
J Biol Chem. 2013 Apr 12;288(15):10265-74. doi: 10.1074/jbc.M112.413542. Epub 2013 Feb 7.
The endothelial cell-specific chemotaxis receptor (ECSCR) is a cell-surface protein selectively expressed by endothelial cells (ECs), with roles in EC migration, apoptosis and proliferation. Our previous study (Verma, A., Bhattacharya, R., Remadevi, I., Li, K., Pramanik, K., Samant, G. V., Horswill, M., Chun, C. Z., Zhao, B., Wang, E., Miao, R. Q., Mukhopadhyay, D., Ramchandran, R., and Wilkinson, G. A. (2010) Blood 115, 4614-4622) showed that loss of ECSCR in primary ECs reduced tyrosine phosphorylation of vascular endothelial growth factor (VEGF) receptor 2/kinase insert domain receptor (KDR) but not VEGF receptor 1/FLT1. Here, we show that ECSCR biochemically associates with KDR but not FLT1 and that the predicted ECSCR cytoplasmic and transmembrane regions can each confer association with KDR. Stimulation with VEGF165 rapidly and transiently increases ECSCR-KDR complex formation, a process blocked by the KDR tyrosine kinase inhibitor compound SU5416 or inhibitors of endosomal acidification. Triple labeling experiments show VEGF-stimulated KDR(+)/ECSCR(+) intracellular co-localization. Silencing of ECSCR disrupts VEGF-induced KDR activation and AKT and ERK phosphorylation and impairs VEGF-stimulated KDR degradation. In zebrafish, ecscr interacts with kdrl during intersomitic vessel sprouting. Human placenta and infantile hemangioma samples highly express ECSCR protein, suggesting a role for ECSCR-KDR interaction in these tissues.
内皮细胞特异性趋化因子受体（ECSCR）是一种选择性表达于内皮细胞（EC）的细胞表面蛋白，在 EC 的迁移、凋亡和增殖中发挥作用。我们之前的研究（Verma, A., Bhattacharya, R., Remadevi, I., Li, K., Pramanik, K., Samant, G. V., Horswill, M., Chun, C. Z., Zhao, B., Wang, E., Miao, R. Q., Mukhopadhyay, D., Ramchandran, R., and Wilkinson, G. A. (2010) Blood 115, 4614-4622）表明，原发性 EC 中 ECSCR 的缺失减少了血管内皮生长因子（VEGF）受体 2/激酶插入结构域受体（KDR）的酪氨酸磷酸化，但不减少 VEGF 受体 1/FLT1。在这里，我们发现 ECSCR 与 KDR 具有生化关联，但与 FLT1 没有关联，并且预测的 ECSCR 胞质和跨膜区域都可以分别与 KDR 结合。VEGF165 刺激可快速且短暂地增加 ECSCR-KDR 复合物的形成，该过程可被 KDR 酪氨酸激酶抑制剂化合物 SU5416 或内体酸化抑制剂阻断。三重标记实验显示 VEGF 刺激诱导 KDR(+) / ECSCR(+) 细胞内共定位。ECSCR 沉默破坏了 VEGF 诱导的 KDR 激活以及 AKT 和 ERK 的磷酸化，并损害了 VEGF 刺激的 KDR 降解。在斑马鱼中，ecscr 在节间血管发芽过程中与 kdrl 相互作用。人胎盘和婴儿血管瘤样本高度表达 ECSCR 蛋白，这表明 ECSCR-KDR 相互作用在这些组织中发挥作用。
