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过程中由许多不同的粘附、吸引和排斥系统引导其轨迹。正常的轴突生长和引导需要在生长锥中整合来自许多不同受体系统的信息。我们的长期目标是确定在视网膜神经轴突发育过程中整合粘附受体功能的环境线索和信号通路。n -钙粘蛋白和β -整合素是两种在视网膜轴突延伸和引导中起决定性作用的粘附系统。我们发现了一个在轴突生长过程中协调调节n -钙粘蛋白和β -整合素功能的途径。当细胞或生长锥接触硫酸软骨素蛋白多糖neurocan时，n -钙粘蛋白和β -整合素的功能都丧失。这种协调功能的丧失与非受体酪氨酸激酶Fer的易位有关，它通常与钙粘蛋白复合体的蛋白质结合到与β -整合素细胞质结构域相关的蛋白质复合体。我们的假设是钙粘蛋白和整合素的协调调节在防止神经节细胞轴突偏离其适当路径中起重要作用。本应用程序的目的是确定铁在钙粘蛋白和整合素功能中的作用，并检查该途径在视网膜神经节细胞轴突发育中的作用。目的1和目的2分别定义了Fer在钙粘蛋白和整合素功能中的作用。我们将确定在Fer存在和不存在的情况下其存在或磷酸化发生改变的效应物，以及这些改变的成分如何调节功能。Aim 3定义了钙粘蛋白细胞质域中负责转导启动铁穿梭信号的调控位点。这将通过N-cadherin的删除和突变，以及神经视网膜中存在的其他I型和II型cadherin的功能比较来完成，以参与cadherin和整合素之间的交叉调节能力。在Aim 4中，我们将通过抑制神经蛋白（启动协调调节的细胞外信号）的结合，以及通过使用细胞渗透性肽来干扰钙粘蛋白和/或整合素的功能，确定这种交叉调节回路在视网膜神经节细胞轴突突起发育中的作用。

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.