Genetic and Molecular Analyses of Protein Biogenesis in the Neuroretina

描述（由申请人提供）：泛素-蛋白酶体系统（UPS）的失调是许多神经退行性疾病的标志性特征，包括视网膜变性，它涉及光受体中蛋白质转换的错误折叠和失调。我们的长期目标是了解UPS-伴侣机制的调节复合体在控制底物降解和折叠中的作用，并利用这些信息确定新的治疗策略的靶点，这些策略目前对UPS的选择性生物学和疾病过程缺乏疗效。本提案的目标是了解维持蛋白质周转和生物发生之间平衡的分子和细胞内机制，这两个紧密耦合的过程对视网膜神经元的功能和生存至关重要，并且与人类各种神经视觉疾病的发病机制有关。实现这一目标将使我们和其他人能够确定新的药理学靶点，并制定治疗策略来操纵ups -伴侣机制，防止在各种视网膜疾病状态和衰老表现下正常或突变蛋白表达的毒性解除，从而导致ups -伴侣机制和神经视觉功能受损。提出的研究建立在我们之前的研究发现的基础上，这些发现表明底物在合成时呈现给蛋白酶体，蛋白酶体的活性在细胞中受到调节和区隔化。ran结合蛋白2 （RanBP2）通过两个不同的结构域，亲环蛋白样结构域（CLD）和亲环蛋白（CY）结构域，是这一过程的关键控制者。这一建议验证了我们的总体假设，即RanBP2及其CLD和CY结构域控制着两个紧密耦合的过程，即ups依赖性的选择性蛋白的转换和生物发生，这对正常和病理生理条件下选择性视网膜神经元和视网膜色素上皮（RPE）细胞的功能和存活至关重要。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CLD和CY结构域在正常和疾病应激条件下调节选择性视网膜神经元的蛋白质稳态和存活中的机制作用。目的1。验证RanBP2功能缺失在视网膜神经元中具有不同的生物学和病理学影响的假设，其中一些可能对这些神经元的生存能力或蛋白质稳态至关重要。目标2。验证RanBP2 CLD活性的选择性功能丧失上调UPS的选择性功能的假设，UPS的选择性功能对选择性视网膜蛋白的稳态、视网膜神经元和RPE细胞的功能和存活至关重要。目标3。验证RanBP2 CY区域的顺式-反式脯氨酸异构酶（PPIase）活性控制对视网膜神经元和RPE细胞的功能或存活至关重要的选择性蛋白的生物发生的假设。

DESCRIPTION (provided by applicant): The deregulation of the ubiquitin-proteasome system (UPS) is a hallmark feature of many neurodegenerative disorders, including retinal degenerations, which involve misfolding and deregulation of protein turnover in photoreceptors. Our long-range objective is to understand the role of a regulatory complex of the UPS- chaperone machinery in controlling substrate degradation and folding and use this information to identify targets for novel therapeutic strategies, which presently lack efficacy toward selective biological and disease processes of the UPS. The goal of this proposal is to understand the molecular and intracellular mechanisms that sustain the balance between turnover and biogenesis of proteins, two tightly coupled processes that are vital for retinal-neuron function and survival and that are implicated in the pathogenesis of a wide variety of neuro-visual disorders of the human. Achievement of this goal will allow us and others to identify novel pharmacological targets and develop therapeutic strategies to manipulate the UPS-chaperone machinery, prevent the toxic deregulation of normal or expression of mutated proteins under various retinal disease states and aging manifestations causing the impairment of the UPS-chaperone machinery and neuro-visual function. The proposed research builds upon our prior research findings which demonstrated that substrates are presented to the proteasome upon synthesis and that the activity of the proteasome is regulated and compartmentalized in the cell. Ran-binding protein 2 (RanBP2) via two distinct domains, the cyclophilin-like (CLD) and cyclophilin (CY) domains, is a key controller of such processes. This proposal tests our overall hypothesis that RanBP2 and its CLD and CY domains control two tightly coupled processes, the UPS-dependent turnover and biogenesis of selective proteins that are critical to the function and survival of selective retinal neurons and retinal pigment epithelium (RPE) cells under normal and pathophysiological conditions. We will test this hypothesis by accomplishing the following specific aims, which focus on the mechanistic roles of RanBP2, and its CLD and CY domains, in the regulation of protein homeostasis and survival of selective retinal neurons under normal and disease stress conditions. Aim 1. Test the hypothesis that loss-of-function of RanBP2 has differential biological and pathological effects among retinal neurons, some of which may be essential to the viability or protein homeostasis of such neurons. Aim 2. Test the hypothesis that selective loss-of-function of the CLD activity of RanBP2 up-regulates selective functions of the UPS that are critical to homeostasis of selective retinal proteins, function and survival of retinal neurons and RPE cells. Aim 3. Test the hypothesis that the cis-trans prolyl isomerase (PPIase) activity in the CY domain of RanBP2 controls the biogenesis of selective proteins that are critical to the function or survival of retinal neurons and RPE cells. PUBLIC HEALTH RELEVANCE: The modulation of protein degradation and biogenesis in the retina is of vital importance to its function. Impairment of these processes is known to underlie the pathogenesis of several degenerative and aging disorders affecting retinal neurons. The proposal aims at elucidating the role of Ran-binding protein 2 in protein homeostasis and allied pathohysiological states in the retina.