Northwestern University, Feinberg School of Medicine, Department of Pediatrics, Chicago, Illinois, USA.
Dev Dyn. 2010 Feb;239(2):598-609. doi: 10.1002/dvdy.22163.
Little is known about the molecules that mediate the attachment of proepicardial cells to the heart. Ephrins are cell surface ligands for Eph tyrosine kinase receptors, molecules known to play a role in cell adhesion and migration. Here, we detected EphrinB ligands in proepicardial and epicardial mesothelial cells (EMCs) using reverse transcriptase-polymerase chain reaction, immunoblotting, immunolocalization, and EphB-Fc binding. Aggregated EphB-Fc fragments clustered ephrinB1 ligands on living EMCs indicating that they are cell surface expressed. In vitro assays demonstrated that ephrinB ligands participate in EMC migration but not cell adhesion. Localization studies in hearts at Hamburger and Hamilton stage 30 and older revealed that ephrinB1 is expressed in the epicardium and subepicardial mesenchyme of the atrioventricular sulcus. EMCs treated with platelet-derived growth factor-BB expressed smooth muscle markers but not ephrinB1. Our study supports an early role for ephrinB ligands for migration of epicardial cells and a later role in perivascular fibroblasts of coronary vessels in the atrioventricular sulcus.
关于介导原心外膜细胞与心脏附着的分子知之甚少。Ephrins 是 Eph 酪氨酸激酶受体的细胞表面配体，这些分子已知在细胞黏附和迁移中发挥作用。在这里，我们使用逆转录-聚合酶链反应、免疫印迹、免疫定位和 EphB-Fc 结合检测了原心外膜和心外膜间皮细胞（EMCs）中的 EphrinB 配体。聚集的 EphB-Fc 片段使活 EMC 上的 EphrinB1 配体聚集，表明它们在细胞表面表达。体外实验表明 EphrinB 配体参与 EMC 迁移而不参与细胞黏附。在 Hamburger 和 Hamilton 阶段 30 及以上的心脏中的定位研究表明 EphrinB1 在房室沟的心外膜和心外膜下间质中表达。用血小板衍生生长因子-BB 处理的 EMCs 表达平滑肌标志物，但不表达 EphrinB1。我们的研究支持 EphrinB 配体在心脏迁移中早期发挥作用，以及在房室沟冠状血管的血管周围成纤维细胞中晚期发挥作用。
