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)功能的失调是许多神经退行性和衰老相关疾病发病机制的显著特征，这些疾病会导致严重的神经功能损害。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的神经保护特性和高效治疗效果的靶点，以延迟或治愈导致神经功能障碍的临床表现。为了实现这一目标，我们提出了一个研究项目，其长期目标是更好地了解控制线粒体动力学和UPS功能的因素的作用，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调节神经元存活中的作用(S)。了解控制线粒体动力学或UPS活性并有助于调节神经元存活的因素的作用(S)，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害的临床表现的发展。我们将集中于确定RAN GTP酶与其高亲和力和多结合靶点之一的RANBP2(RANBP2)之间的功能关系。这一建议检验了我们的总体假设，即RANBP2的RAN GTPase与RANBP2的RAN结合域-2和-3(RBD2和RBD3)之间的关联构成了一个新的分子开关，控制RANBP2在调节UPS功能、Kinesin-1引起的线粒体动力学和神经元存活方面的效应域。我们将通过实现以下特定目标来验证这一假说，这些目标集中在RanBP2及其RBD2和RBD3在正常和疾病应激条件下调节线粒体动态、蛋白质动态平衡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功能缺失促进不同类型神经细胞在线粒体转运和存活方面的差异的假说。目的2.验证RANBP2的RBD3功能缺失促进不同神经细胞类型的UPS活性差异的假说。目的3.在光感受器死亡、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三种应激性神经变性小鼠模型中，验证Ran GTP酶依赖的线粒体转运或UPS活性的损害促进选择性神经元的神经保护或细胞死亡的假说。 与公共卫生相关：对线粒体贩运和控制蛋白质降解的机制的放松管制是导致神经退化的许多神经疾病的基础。本研究旨在确定和阐明RanGTP酶和Ran结合蛋白-2等因子在正常和疾病应激条件下控制线粒体动态、蛋白质降解和各种类型神经元存活中的作用。

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.