Coordinating Adhesion Receptors in Axon Growth

描述（由申请人提供）：视网膜神经节细胞轴突在发育期间通过许多不同的粘附、吸引和排斥系统沿其轨迹被引导沿着。正确的轴突生长和引导需要来自许多不同受体系统的信息整合到生长锥中。我们的长期目标是确定环境的线索和信号通路，整合在神经视网膜轴突的发展过程中粘附受体的功能。N-钙粘蛋白和β 1-整合素是在视网膜轴突延伸和引导中起决定性作用的两种粘附系统。我们已经发现了一个途径，协调调节N-钙粘蛋白和β 1-整联蛋白的功能在轴突生长。当细胞或生长锥接触硫酸软骨素蛋白聚糖神经聚糖时，N-钙粘蛋白和β 1-整联蛋白功能均丧失。这种功能的协同丧失与非受体酪氨酸激酶Fer从其在钙粘蛋白蛋白复合物中的通常缔合物易位到与β 1-整联蛋白的胞质结构域缔合的蛋白质复合物相关。我们的假设是，协调调节的钙粘蛋白和整合素起着重要的作用，防止神经节细胞轴突偏离其适当的path. The目标的应用程序是定义的钙粘蛋白和整合素功能的作用，并检查视网膜神经节细胞轴突的发展这一途径的作用。目的1和2分别定义了Fer在钙粘蛋白和整合素功能中的作用。我们将确定其存在或磷酸化在Fer的存在和不存在下改变的效应物，以及这些改变的组分如何调节功能。目的3确定了钙粘蛋白胞质结构域中负责转导启动Fer穿梭的信号的调节位点。这将通过N-钙粘蛋白的缺失和诱变以及存在于神经视网膜中的其他I型和II型钙粘蛋白参与钙粘蛋白和整合素之间交叉调节的能力的功能比较来实现。在目标4中，我们将确定这种交叉调节回路在视网膜神经节细胞轴突投射的发展中的作用，通过抑制神经聚糖的结合，启动协调调节的细胞外信号，并通过使用细胞渗透性肽来干扰钙粘蛋白和/或整合素功能。

DESCRIPTION (provided by applicant): Retinal ganglion cell axons are guided along their trajectories during development by many different systems of adhesion, attraction and repulsion. Proper axon growth and guidance requires integration in the growth cone of information from many distinct receptor systems. Our long term goals are to identify the environmental cues and signaling paths that integrate adhesion receptor function during development of axons in the neural retina. N-cadherin and beta1-integrins are two of the adhesion systems that play decisive roles in retinal axon elongation and guidance. We have discovered a pathway which coordinately regulates N-cadherin and beta1-integrin function during axon outgrowth. When cells or growth cones contact the chondroitin sulfate proteoglycan neurocan, both N-cadherin and beta1-integrin function is lost. This coordinate loss of function correlates with translocation of the non-receptor tyrosine kinase Fer from its usual association in the cadherin complex of proteins to the complex of proteins associated with the cytoplasmic domain of beta1-integrin. Our hypothesis is that coordinate regulation of cadherin and integrin plays an important role in preventing ganglion cell axons from straying from their appropriate path. The goal of this application is to define the role of Fer in cadherin and integrin function and to examine the role of this pathway in the development of retina ganglion cell axons. Aims 1 and 2 define the role of Fer in the function of cadherin and integrin respectively. We will identify effectors whose presence or phosphorylation is altered in the presence and absence of Fer and how these altered components regulate function. Aim 3 defines the regulatory site in the cadherin cytoplasmic domain responsible for transducing the signal initiating the shuttling of Fer. This will be accomplished by deletion and mutagenesis of N-cadherin, as well as functional comparison of other Type I and II cadherins present in the neural retina for the ability to participate in cross-regulation between cadherin and integrin. In Aim 4 we will determine the role of this cross regulatory circuit in development of retinal ganglion cell axon projections through inhibition of the binding of neurocan, the extracellular signal that initiates coordinate regulation, and through the use of cell permeable peptides to perturb cadherin and/or integrin function.