Defining the role of C. elegans Parkin/PDR-1 in glial engulfment of neuron fragments

项目摘要 胶质细胞吞噬活神经元的碎片，以调节专门的神经元末梢。大量证据 表明神经胶质细胞对神经元碎片的吞噬是神经胶质细胞的广泛调节和发育功能， 中枢神经系统和外周神经系统。在正常情况下，这一过程是如何调节的， 在任何系统中都不清楚，但最近表明，这一过程的错误调节有助于早期突触 阿尔茨海默病小鼠模型的损失。此外，视网膜色素对吞噬作用的错误调节 眼睛中的上皮细胞可能导致某些形式的黄斑变性。突触丧失和感觉 功能障碍是帕金森病的早期标志，然而神经胶质的参与是未知的。损失 E3泛素连接酶Parkin的功能有助于帕金森病的发作和进展。的 在哺乳动物和无脊椎动物模型中，帕金介导的线粒体自噬在神经元中的作用得到了很好的表征，但 尽管在几种神经胶质亚型中表达，但Parkin在神经胶质中的功能尚不清楚。我们最近 显示在C。在线虫中，特化感觉神经元的碎片被相关的神经胶质细胞吞噬。 首先，我发现帕金同源物pdr-1的功能丧失会导致帕金森病的发病率显著增加。 数目的神经元碎片被神经胶质细胞吞噬，表明PDR-1抑制神经胶质细胞的吞噬。C. elegans 在历史上是一个强大的模型，用于揭示吞噬机制，细胞 识别、吞噬和降解细胞碎片。我建议用这个系统来探测 Parkin/PDR-1调节神经元片段的神经胶质吞噬作用。我将确定细胞的具体要求， PDR-1，探测其E3连接酶活性的底物，其可能在神经胶质细胞吞噬中起作用，并最终询问其作用是否 在神经胶质吞噬中起作用。

PROJECT SUMMARY Glia engulf fragments of live neurons in order to regulate specialized neuron endings. Amounting evidence indicates the engulfment of neuron fragments by glia is a broad regulatory and developmental function of glia in both the central and peripheral nervous systems. How this process is regulated under normal conditions is unclear in any system, but it was recently shown that mis-regulation of this process contributes to early synapse loss in mouse models of Alzheimer’s disease. Furthermore, mis-regulation of phagocytosis by Retinal Pigment Epithelium cell in the eye may cause some forms of macular degeneration. Synapse loss and sensory disfunction are early hallmarks of Parkinson’s disease, however the involvement of glia is unknown. Loss of function of the E3 ubiquitin ligase Parkin contributes to the onset and progression of Parkinson’s disease. The role of Parkin mediating mitophagy in neurons is well characterized in mammals and invertebrate models, but despite being expressed in several glial subtypes, the functions of Parkin in glia are unknown. We have recently shown in C. elegans that fragments of a specialized sensory neuron are engulfed by an associated glial cell. Preliminarily, I have found that loss of function of the Parkin ortholog pdr-1 elicits a substantial increase in the number neuron fragments engulfed by glia, demonstrating that PDR-1 inhibits engulfment by glia. C. elegans has historically been a powerful model used to unearth the mechanisms of phagocytosis by which cells recognize, engulf, and degrade cellular debris. I propose to use this system to probe the mechanism by which Parkin/PDR-1 regulates glial phagocytosis of neuron fragments. I will determine the cell-specific requirements of PDR-1, probe substrates of its E3 ligase activity that may have roles in glial engulfment, and finally ask if its role in mitophagy has a function in glial engulfment.