B-RAF drives regenerative axon growth in the optic nerve in vivo

描述(申请人提供)：包括视神经在内的成熟中枢神经系统(CNS)中受损的轴突不能自发再生。这种无法再生的能力会导致中枢神经系统损伤后的永久性残疾。更好地了解轴突再生的障碍，以及克服这些障碍的新方法，对于开发可能改善未来神经系统损伤患者命运的新药和程序是必要的。我们的目标是通过提升内在生长信号来实现中枢神经系统轴突再生。众所周知，RAF激酶可以驱动胚胎感觉神经元中的轴突快速生长；因此，我们现在将激活视网膜中的这一激酶。我们的第一个目标是使用有条件的B-RAF功能获得小鼠模型来促进受损视神经的再生。然后，我们将测试RAF信号下游的信号分子-meks、ERKs和RND-在B-RAF驱动的视网膜轴突再生中的作用(目标2)。接下来，我们计划将B-RAF的激活和PI3-激酶信号的激活(使用PI3-激酶拮抗剂PTEN的敲除)结合起来，看看这种结合是否会进一步促进体内再生视神经轴突的生长(目标3)。如果我们能观察到任何视束核的再生，我们将测试小鼠的视觉功能是否恢复；这种功能恢复是所有轴突再生研究的最终目标。这项拟议的研究将确定RAF信号及其下游效应因子在视神经再生中的作用，为翻译研究和新药鉴定奠定基础 目标。

DESCRIPTION (provided by applicant): Injured axons in the mature central nervous system (CNS), including the optic nerve, cannot regenerate spontaneously. This inability to regenerate causes permanent disability after CNS injuries. A better understanding of the impediments to axon regeneration, and novel approaches towards overcoming them, are necessary for the development of new drugs and procedures that may improve the fate of patients with nervous system injury in the future. Our goal is to enable CNS axon regeneration by elevating intrinsic growth signaling. The RAF kinase is known to drive fast axon growth in embryonic sensory neurons; we therefore will now activate this kinase in the retina. Our first aim is to promote regeneration in the injured optic nerve using a conditional B-RAF gain-of-function mouse model. We will then test the roles of signaling molecules downstream of RAF signaling - the MEKs, ERKs and RNDs - for their contributions to B-RAF-driven retinal axon regeneration (Aim 2). Next, we plan to combine activation of B-RAF with activation of PI3-kinase signaling (using a knock-out of the PI3-kinase antagonist PTEN) to see whether this combination will further boost regenerative optic nerve axon growth in vivo (Aim 3). If we can observe regeneration into any of the optic tract nuclei, we will test the mice for any recovery of visual function; such functional recovery being the ultimate goal of all axon regeneration studies. The proposed study will define the roles of RAF signaling and its downstream effectors in the context of optic nerve regeneration, laying groundwork for translational research and for the identification of novel drug targets.