Genetic and Molecular Dissection of RanBP2-Mediated RanGTPase Functions

描述（由申请人提供）：线粒体动力学和泛素-蛋白酶体系统（UPS）功能的解除管制是许多神经退行性和衰老相关疾病导致严重神经损伤的发病机制的标志性特征。目前促进神经保护的治疗干预措施缺乏治疗效果。我们的长期目标是确定具有新型神经保护特性和高治疗效果的靶点，以延缓或治愈引起神经损伤的临床表现。为了实现这一目标，我们提出了一个研究项目，其长期目标是提高对控制线粒体动力学和UPS功能的因素的作用的理解，识别这些因素和过程之间的串扰过程，以及这些因素和过程在神经元存活调节中的作用。了解控制线粒体动力学或UPS活性的因素的作用，并有助于神经元存活的调节，将使我们和其他人能够创造新的价值靶点和治疗策略，以延缓或治愈导致严重神经损伤的临床表现的发展。我们将重点确定RAN GTPase与其高亲和力和多结合靶标之一RAN结合蛋白2 （RANBP2）之间的功能关系。这一提议验证了我们的总体假设，即RAN GTPase与RANBP2的RAN结合结构域-2和-3 （RBD2和RBD3）之间的关联构成了一种新的分子开关，以控制RANBP2的效应结构域，从而调节UPS功能、激酶-1介导的线粒体动力学和神经元存活。我们将通过实现以下具体目标来验证这一假设，重点关注RanBP2及其RBD2和RBD3在正常和疾病应激条件下调控线粒体动力学、蛋白质稳态和选择性神经元存活中的机制作用。目的1。验证RANBP2的RBD2或RBD3的功能缺失对线粒体运输和神经元细胞存活的不同影响。目标2。验证RANBP2的RBD3功能缺失促进不同神经元细胞类型UPS活性差异效应的假设。目标3。在三种应激性神经退行性小鼠模型中：光诱导的光感受器死亡、高眼压诱导的神经节细胞死亡和MPP+诱导的多巴胺能神经元死亡，验证线粒体运输或UPS活性的RAN gtpase依赖性调节损伤促进选择性神经元的神经保护或细胞死亡的假设。

DESCRIPTION (provided by applicant): The deregulation of mitochondria dynamics and function of the ubiquitin-proteasome system (UPS) are hallmark features of the pathogenesis of numerous neurodegenerative and aging-related disorders causing severe neurological impairment. Current therapeutic interventions that promote neuroprotection lack therapeutic efficacy. Our long-term goal is to identify targets with novel neuroprotective properties and high therapeutic efficacies that delay the onset of or cure clinical manifestations causing neurological impairment. To attain this goal we propose a research project whose long-term objective is the development of improved understanding of the role of factors controlling mitochondria dynamics and UPS functions, the identification of cross-talk processes between these factors and processes, and the effect(s) of such factors and processes in modulation of neuronal survival. Understanding the role(s) of factors that control mitochondria dynamics or UPS activity and contribute to the modulation of neuronal survival, would allow us and others to create novel value targets and therapeutic strategies to delay or cure the development of clinical manifestations leading to severe neurological impairments. We will focus on determining the functional relationships between RAN GTPase and one of its high-affinity and multi-binding targets, the RAN-binding protein 2 (RANBP2). This proposal tests our overall hypothesis that the associations between RAN GTPase and, the RAN-binding domains-2 and -3 (RBD2 and RBD3) of RANBP2, constitute a novel molecular switch to control effector domains of RANBP2 in the modulation of UPS function, mitochondria dynamics by kinesin-1, and neuronal survival. We will test this hypothesis by accomplishing the following specific aims, which focus on the mechanistic roles of RanBP2 and its RBD2 and RBD3 in the regulation of mitochondria dynamics, protein homeostasis and survival of selective neurons under normal and disease stress conditions. Aim 1. Test the hypothesis that loss-of-function of the RBD2 or RBD3 of RANBP2 promotes differential effects in mitochondria trafficking and survival among neuronal cell types. Aim 2. Test the hypothesis that loss-of-function of the RBD3 of RANBP2 promotes differential effects in UPS activity among neuronal cell types. Aim 3. Test the hypothesis that impairment of RAN GTPase-dependent modulation of mitochondria trafficking or UPS activity promotes either neuroprotection or cell death of selective neurons in three mouse models of stress-induced neurodegeneration: light-induced death of photoreceptors, high intraocular pressure-induced ganglion cell death, and MPP+induced death of dopaminergic neurons. PUBLIC HEALTH RELEVANCE: The deregulation of trafficking of mitochondria and of the machinery controlling protein degradation underlies numerous neurological disorders leading to neurodegeneration. This study seeks to identify and elucidate the role of factors, such as RanGTPase and Ran-binding protein-2, in controlling mitochondria dynamics and protein degradation and survival of various types of neurons under normal and disease stress conditions.