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

项目总结 胶质细胞吞噬活神经元的碎片，以调节专门的神经元终末。举证 提示神经胶质细胞吞噬神经元碎片是胶质细胞广泛的调节和发育功能。 中枢神经系统和外周神经系统。在正常情况下，这一过程是如何被调控的 在任何系统中都不清楚，但最近研究表明，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丢失。此外，视网膜色素对吞噬功能的错误调节 眼部上皮细胞可能导致某种形式的黄斑变性。突触丢失与感觉 功能障碍是帕金森氏病的早期特征，但神经胶质细胞的参与尚不清楚。损失 泛素连接酶E3的功能与帕金森氏症的发生和发展有关。这个 Parkin在神经元中介导有丝分裂的作用在哺乳动物和无脊椎动物模型中得到了很好的表征，但 虽然Parkin在几种胶质细胞亚型中都有表达，但其在胶质细胞中的功能尚不清楚。我们最近做了 在线虫中显示，特定感觉神经元的片段被相关的神经胶质细胞吞噬。 我初步发现，Parkin直系同源基因PDR-1功能的丧失会导致Pdr-1的 大量神经元碎片被胶质细胞吞噬，表明PDR-1抑制了胶质细胞的吞噬。线虫 历来是用来揭示细胞吞噬机制的强大模型 识别、吞噬和降解细胞碎片。我建议用这个系统来探索 Parkin/PDR-1调节神经元片段的神经胶质吞噬作用。我将确定特定于细胞的要求 PDR-1，探测其E3连接酶活性的底物，可能在胶质细胞吞噬中发挥作用，最后询问其作用 吞噬有丝分裂在胶质细胞吞噬中起作用。

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.