Pum2-dependent translational regulation of a-SYN near mitochondria in neurites

描述（由申请人提供）：路易神经突（LNs）和路易小体（LBs）中存在α -突触核蛋白（α -syn）聚集，这是帕金森病（PD）的病理标志，线粒体功能障碍是PD发病机制的两个核心组成部分。已知的α - syn在突触末端的生理作用有限，这提高了α - syn mRNA被转运到神经突及其翻译受局部控制的可能性。事实上，我们最近发现α - syn mRNA被转运到完全分化的人类多巴胺能神经元细胞的神经突中。我们还发现Pum2是哺乳动物PUF家族RNA结合蛋白的一个类似物，与α - syn 3'UTR的PUM结合基元结合，并负责神经炎定位以及α - syn mRNA的翻译抑制。呼吸复合体I抑制产生的线粒体ROS导致线粒体相关mRNA局部翻译α - syn，提示Pum2可能将线粒体信号传递给α - syn翻译。虽然线粒体和α - syn之间的相互关系是疾病发展的基础，但控制这种串扰的分子机制仍然难以捉摸。我们的中心假设是Pum2负责α - syn mRNA转运到近线粒体室，α - syn翻译调节和神经突聚集。本项目的目的是通过pum2介导的线粒体相关α - syn mRNA的翻译调节来了解α - syn与神经突线粒体之间的相互作用。为实现这些目标，我们提出以下三个具体目标：研究Pum2在α - syn mRNA线粒体定位中的作用。目标2。研究线粒体ROS如何控制α - syn翻译。目标3。确定线粒体附近新合成的α - syn如何影响线粒体断裂和神经突中α - syn聚集。该项目的成功完成将为我们对控制神经突α - syn水平的分子机制以及线粒体ROS如何参与α - syn调节的理解带来范式转变。该项目的预期结果将为以下方面开辟新的途径：1)神经突中α - syn的3' utr依赖性转录后调控以及Pum2在这一过程中的作用；2)神经突中α - syn与线粒体之间的密切串扰；3)α - syn对线粒体断裂和LN形成的贡献。

DESCRIPTION (provided by applicant): The presence of alpha-synuclein (alpha-SYN) aggregate in Lewy neurites (LNs) and Lewy bodies (LBs), the pathological hallmarks of Parkinson's disease (PD), and mitochondrial dysfunction are two central components in PD pathogenesis. Known physiological roles of alpha-SYN are limited in synaptic terminals, raising the possibility that alpha-SYN mRNA is transported to neurites and its translation is locally controlled. In fact, we have recently found that alpha-SYN mRNA is translocated into neurites of fully differentiated human dopaminergic neuronal cells. We also identified that Pum2, a paralogue of mammalian PUF family RNA binding protein, binds to a PUM binding motif of the alpha-SYN 3'UTR and is responsible for neuritic localization as well as translational repression of alpha-SYN mRNA. Mitochondrial ROS generated by respiratory complex I inhibition led to local translation of alpha-SYN from mRNA associated with mitochondria, suggesting that Pum2 might transmit mitochondrial signal to alpha-SYN translation. Although it is obvious that there is an inter- relationship between mitochondria and alpha-SYN underlying the development of disease, molecular mechanisms governing this cross-talk remain elusive. Our central hypothesis is that Pum2 is responsible for alpha-SYN mRNA transport to the juxta-mitochondrial compartment, alpha-SYN translational regulation and aggregation in neurites. The objectives of this project are to understand the interplay between alpha-SYN and mitochondria in neurites through Pum2-mediated translational regulation of mitochondria-associated alpha-SYN mRNA. To achieve these objectives we propose the following three specific aims: Aim 1. Examine the role of Pum2 in mitochondrial localization of alpha-SYN mRNA. Aim 2. Examine how mitochondrial ROS control alpha-SYN translation. Aim 3. Determine how newly synthesized alpha-SYN near mitochondria affects mitochondrial fragmentation and alpha-SYN aggregation in neurites. The successful completion of the project will bring a paradigm shift in our understanding of molecular mechanisms that control alpha-SYN level in neurites and how mitochondrial ROS contribute to this alpha-SYN regulation. The results expected from the project will open new avenues to understand 1) 3'UTR-dependent posttranscriptional regulation of alpha-SYN in neurites and Pum2's role in this process, 2) intimate crosstalk between alpha-SYN and mitochondria in neurites and 3) its contribution to mitochondrial fragmentation and LN formation.