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

描述（由申请人提供）：成熟中枢神经系统（CNS）损伤的轴突，包括视神经，不能自发再生。这种再生能力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，对于未来可能改善神经系统损伤患者命运的新药物和新程序的开发是必要的。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的再生。已知RAF激酶驱动胚胎感觉神经元的快速轴突生长；因此我们现在要激活视网膜上的激酶。我们的第一个目标是使用条件B-RAF功能获得小鼠模型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（Aim 2）。接下来，我们计划将B-RAF的激活与pi3激酶信号的激活（使用敲除pi3激酶拮抗剂PTEN）结合起来，看看这种组合是否会进一步促进再生视神经轴突的体内生长（目的3）。如果我们能观察到再生进入任何视神经束核，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。本研究将明确RAF信号及其下游效应物在视神经再生中的作用，为转化研究和新药鉴定奠定基础

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.