EphB1 signaling in retinal axon guidance

描述(申请人提供)：这项拟议的研究利用体外和体内测试来确定特定受体-配体(EphB1-ephin-B2)相互作用的下游信号机制，该相互作用通过调节视交叉处腹颞部(未交叉)视网膜轴突的排斥而形成双眼视觉。为了证明这种相互作用的特异性和充分性，我们将在体外将EphB1和EphB2导入EphB1缺失的视网膜外植体和体内的胚胎视网膜中，并研究轴突投射和对ePhin-B2底物的反应。在异源系统中，EphB1可以激活许多下游信号通路，但尚不清楚其中哪些是生物学上相关的。一系列实验将表征生长激素钙瞬变在调节EphB1对ePhin-B2的排斥中的作用。同时，更多的研究将使用药理学方法来确定EphB1介导的ePhin-B2排斥所需的途径。最后，EphB1受体中的一系列突变将被引入这些相同的检测中，以揭示哪些区域负责将EphB1的激活转化为排斥。这些实验将增加我们在轴突引导和生长锥体动力学领域的知识。

DESCRIPTION (provided by applicant): The proposed research utilizes in vitro and in vivo assays to identify downstream signaling mechanisms of a specific receptor-ligand (EphB1-ephrin-B2) interaction that patterns binocular vision by mediating repulsion of ventrotemporal (uncrossed) retinal axons at the optic chiasm. To demonstrate the specificity and sufficiency of this interaction, EphB1 and EphB2 will be introduced into EphB1 null retinal explants in vitro and embryonic retinae in vivo, and axon projections and responses to ephrin-B2 substrates will be characterized. EphB1 can activate numerous downstream signaling pathways in heterologous systems, but it is unknown which of these are biologically relevant. A series of experiments will characterize the role of growth cone calcium transients in mediating EphB1 repulsion from ephrin-B2. In tandem, additional studies will use pharmacological methods to identify which pathways are required for EphB1-mediated repulsion from ephrin-B2. Lastly, a series of mutations in the EphB1 receptor will be introduced in these same assays to reveal which domains are responsible for transducing EphB1 activation into repulsion. These experiments will increase our knowledge in the fields of axon guidance and growth cone dynamics.