EphB1 signaling in retinal axon guidance

描述（由申请人提供）：拟议的研究利用体外和体内试验来鉴定特定受体-配体（EphB 1-ephrin-B2）相互作用的下游信号传导机制，该相互作用通过介导视交叉处的腹颞（未交叉）视网膜轴突的排斥来形成双眼视觉。为了证明这种相互作用的特异性和充分性，将EphB 1和EphB 2引入体外EphB 1无效视网膜外植体和体内胚胎视网膜中，并表征轴突投射和对肝配蛋白-B2底物的反应。EphB 1可以激活异源系统中的许多下游信号通路，但尚不清楚这些通路中哪些是生物学相关的。一系列实验将表征生长锥钙瞬变在介导EphB 1排斥肝配蛋白-B2中的作用。同时，其他研究将使用药理学方法来确定EphB 1介导的ephrin-B2排斥所需的途径。最后，将在这些相同的测定中引入EphB 1受体中的一系列突变，以揭示哪些结构域负责将EphB 1激活转换为排斥。这些实验将增加我们在轴突导向和生长锥动力学领域的知识。

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.