The role of the ubiquitin-proteasome system in photoreceptor degeneration

项目总结 遗传性视网膜变性，包括视网膜色素变性(RP)，起源于近200个基因突变 影响光感受器细胞的基因(在反相的情况下为杆状)。治疗这些疾病的治疗选择是 有限的。治疗这些疾病的一个可能的方法是研究常见的病理生物学机制。 在多重突变的下游。例如，许多与视网膜退化有关的突变会导致 光感受器蛋白折叠不良，并被靶向蛋白酶体进行降解。这表明一种 改变的细胞蛋白平衡(即蛋白质合成和降解之间的平衡)之间的联系 和光感受器退化。到目前为止，对这种联系的任何机械性理解都还处于初级阶段。 本方案中的实验将评估泛素-蛋白酶体系统(UPS)的功能，即 选择性降解蛋白质的细胞机制，在两种视网膜小鼠模型的背景下 与错误折叠的蛋白质的产生有关的退化。UPS的蛋白质降解通常是由 当蛋白质被泛素化标记为降解时，这使蛋白酶体能够识别和 降解蛋白质。许多蛋白质还需要通过涉及伴侣的分子复合体进行加工。 P97，然后它们才能被蛋白酶体识别。多鼠视网膜模型的最新研究进展 变性表明，突变棒在细胞开始之前受到UPS能力不足的影响 死亡。然而，在这些模型中限制蛋白质降解的特定UPS成分仍然存在 未知。这项提案的目标是确定这一限制因素，这将为 遗传性视网膜变性的药物和基因治疗方法的发展。 这项提案的目标1试图确定UPS介导的突变棒中的蛋白质降解是否 受第97页限制。这将通过测量不依赖于P97的突变棒中的累积来实现 UPS功能记者。目标2将调查UPS受到限制的可能性为 WT和WT突变小鼠UbG76VGFP泛素化的比较 P97和蛋白酶体抑制剂。在目标3中，确定的限制UPS组件将在 突变棒，以及由此产生的UPS活性、棒退化和棒功能将被评估。结果是 这些目标将确定UPS的关键部件，其容量在杆死亡之前已不堪重负。 拟议的工作是对正在进行的不间断电源的首次系统审查 光感受器变性，将促进对其病理基础因素的理解 复杂的眼病。

PROJECT SUMMARY Inherited retinal degenerations, including retinitis pigmentosa (RP), originate from mutations in nearly 200 genes affecting photoreceptor cells (rods in the case of RP). Therapeutic options for treating these diseases are limited. One possible approach to treat these conditions is to study the common pathobiological mechanisms downstream of multiple mutations. For example, many mutations linked to retinal degenerations cause photoreceptor proteins to fold poorly and to be targeted to the proteasome for degradation. This suggests a connection between altered cellular proteostasis (i.e. the balance between protein synthesis and degradation) and photoreceptor degeneration. So far, any mechanistic understanding of this connection is still in its infancy. The experiments in this proposal will evaluate the function of the ubiquitin-proteasome system (UPS), the cellular machinery that selectively degrades proteins, in the context of two mouse models of retinal degeneration linked to production of misfolded proteins. Protein degradation by the UPS is typically initiated when a protein is marked for degradation by ubiquitination, which enables the proteasome to recognize and degrade the protein. Many proteins also require processing by molecular complexes involving the chaperone P97 before they can be recognized by proteasomes. Recent work in multiple mouse models of retinal degeneration demonstrated that mutant rods suffer from insufficient UPS capacity prior to the onset of cell death. However, the specific UPS component that is limiting protein degradation in these models remains unknown. The goal of this proposal is to identify this limiting component, which will pave the way for the development of pharmacologic and gene therapy approaches for treatment of inherited retinal degenerations. Aim 1 of this proposal seeks to determine whether UPS-mediated protein degradation in mutant rods is limited by P97. This will be accomplished by measuring the accumulation in mutant rods of a P97-independent reporter of UPS function. Aim 2 will investigate the possibility that the UPS is limited is at the level of ubiquitination by comparing the rate of UbG76VGFP ubiquitination between WT and mutant mice treated with P97 and proteasome inhibitor. In Aim 3 the identified limiting UPS component will be overexpressed in mutant rods, and resulting UPS activity, rod degeneration, and rod function will be evaluated. The results of these Aims will identify the critical component of the UPS whose capacity is overwhelmed prior to rod death. The proposed work represents the first systematic examination of the UPS in the context of ongoing photoreceptor degeneration and will advance the understanding of the factors underlying the pathology of this complex eye disease.