Signaling Scaffolds and Survival in Stroke

描述（由申请人提供）：为什么成熟中枢神经系统（CNS）的神经元在损伤后会死亡？脑白质缺血（脑卒中）可导致轴突损伤，并在大多数情况下导致中枢神经系统神经元死亡。因此，例如，缺血性视神经病变导致视网膜神经节细胞（RGC，一种中枢神经系统神经元）功能障碍和死亡，以及永久性视力丧失。尽管许多细胞死亡和凋亡的下游分子途径正在深入研究中，但轴突损伤后调节存活和轴突再生的上游信号尚不清楚。最近的证据表明，RGCs在轴突损伤后死亡有两个原因：它们与目标来源的营养信号切断，并且它们对这些信号的反应减弱。营养反应性、存活和再生可以通过提高环AMP （cAMP）来增强，但信号转导途径在很大程度上尚未得到研究。在这里，我们将分别使用啮齿动物视网膜和视神经作为CNS神经元及其轴突和白质通路的模型系统，并在视神经白质中风的新模型中测试称为AKAPs的支架蛋白家族的区隔信号调节存活和再生信号的假设。在三个具体目标中，我们将(1)确定主要神经元中负责cAMP信号传导的特异性腺苷酸环化酶；(2)确定cAMP增强的特异性akap相关信号通路，并有助于神经元的存活和再生；(3)确定在体内操纵akap介导的信号小体是否能调节缺血性轴突损伤后神经元的存活和再生。我们希望通过这些实验来确定缺血性轴突损伤后RGC存活失败的分子基础，并最终开发出维持白质缺血后CNS神经元存活的新疗法。

DESCRIPTION (provided by applicant): Why do neurons in the mature central nervous system (CNS) die after injury? White matter ischemia (stroke) leads to axon injury and then in most cases to death of CNS neurons. Thus, for example, ischemic optic neuropathy leads to retinal ganglion cell (RGC, a type of CNS neuron) dysfunction and death, and permanent loss of vision. Although many of the downstream molecular pathways of cell death and apoptosis are under intensive study, the upstream signals that regulate survival and axon regeneration after axon injury are not known. Recent evidence suggests that RGCs die after axon injury for two reasons: they are cut off from target-derived trophic signals, and they become less responsive to such signals. Trophic responsiveness, survival and regeneration can be enhanced by elevating cyclic AMP (cAMP), but the signal transduction pathways remain largely unstudied. Here we will use the rodent retina and optic nerve as a model system for CNS neurons and their axonal, white matter pathways, respectively, and test the hypothesis that compartmentalized signaling on a family of scaffold proteins called AKAPs regulate survival and regeneration signaling in a novel model of white matter stroke in the optic nerve. In three Specific Aims, we will (1) identify the specific adenylyl cyclases responsible for cAMP signaling in primary neurons~ (2) identify the specific AKAP-related signaling pathways potentiated by cAMP and contributing to neuronal survival and regeneration~ and (3) determine whether manipulating AKAP-mediated signalosomes in vivo regulates neuronal survival and regeneration in vivo after ischemic axon injury. We hope through these experiments to determine the molecular basis for the failure of RGC survival after ischemic axon injury, and ultimately to develop new treatments to maintain CNS neuronal survival after white matter ischemia.