Anfosso F, Bardin N, Vivier E, Sabatier F, Sampol J, Dignat-George F
INSERM EMI 00-19 Physiopathologie de l'Endothélium, UFR Pharmacie, Université de la Mediterranée, 13385 Marseille, France.
J Biol Chem. 2001 Jan 12;276(2):1564-9. doi: 10.1074/jbc.M007065200.
CD146 (S-Endo 1 Ag or MUC18) is a transmembrane glycoprotein expressed on endothelial cells on the whole vascular tree. CD146 is located at the intercellular junction where it plays a role in the cohesion of the endothelial monolayer. CD146 engagement initiates an outside-in signaling pathway involving the protein tyrosine kinases FYN and FAK as well as paxillin. Here we report that CD146 engagement by its specific monoclonal antibody in human umbilical vein endothelial cells induces a Ca(2+) influx that is sensitive to thapsigargin and EGTA treatment, indicating that CD146 engagement initiates a store-operated calcium mobilization. In addition, biochemical and pharmacological analysis revealed that CD146 engagement initiates the tyrosine phosphorylation of phospholipase C-gamma, Pyk2, and p130(Cas). Pharmacological inhibition of Ca(2+) flux with 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acetoxymethyl ester and EGTA indicated that an increase in Ca(2+) is required for Pyk2 and p130(Cas) tyrosine phosphorylation. Moreover, a complex association was observed between Pyk2, p130(Cas), and paxillin. These results indicate that CD146 is coupled to a FYN-dependent pathway that triggers Ca(2+) flux via phospholipase C-gamma activation leading subsequently to the tyrosine phosphorylation of downstream targets such as Pyk2, p130(Cas), FAK, and paxillin. In addition to its role in cell-cell adhesion, CD146 is a signaling molecule involved in the dynamics of actin cytoskeleton rearrangement.
CD146（S-Endo 1抗原或MUC18）是一种跨膜糖蛋白，在整个血管树的内皮细胞上表达。CD146位于细胞间连接处，在内皮单层的黏附中发挥作用。CD146的结合启动了一条由外向内的信号通路，涉及蛋白酪氨酸激酶FYN、FAK以及桩蛋白。在此我们报告，在人脐静脉内皮细胞中，其特异性单克隆抗体与CD146结合会诱导Ca(2+)内流，该内流对毒胡萝卜素和乙二醇双四乙酸（EGTA）处理敏感，这表明CD146的结合启动了储存式钙动员。此外，生化和药理学分析显示，CD146的结合启动了磷脂酶C-γ、黏着斑激酶2（Pyk2）和p130（Cas）的酪氨酸磷酸化。用1,2-双（邻氨基苯氧基）乙烷-N,N,N',N'-四乙酸乙酰甲酯和EGTA对Ca(2+)通量进行药理学抑制表明，Pyk2和p130（Cas）的酪氨酸磷酸化需要Ca(2+)增加。此外，还观察到Pyk2、p130（Cas）和桩蛋白之间存在复杂的关联。这些结果表明，CD146与一条依赖FYN的信号通路偶联，该通路通过磷脂酶C-γ激活触发Ca(2+)通量，随后导致下游靶点如Pyk2、p130（Cas）、FAK和桩蛋白的酪氨酸磷酸化。除了在细胞间黏附中的作用外，CD146还是一种参与肌动蛋白细胞骨架重排动态过程的信号分子。
