Investigating physiologic and pathophysiologic connections between the Parkinson's disease protein alpha-synuclein and RNA binding proteins

α-突触核蛋白（αS）在路易体中的神经元聚集是一个关键的标志。 阿尔茨海默病和相关病症（ADRD），包括路易体痴呆（LBD）， 帕金森病伴痴呆（PDD）和混合AD/LB痴呆。统称 疾病影响着数百万美国公民。因此，了解αS毒性的机制是关键 对认识和治疗ADRD有重要意义。αS与细胞膜可逆结合 这种相互作用显然对毒性很重要，但潜在的机制 仍然不清楚。此外，αS在胞质溶胶中也非常丰富。αS在不同的 细胞区室以及当αS异常时，这可能与神经毒性相关 ADRD中的累积仍然未知。我们先前广泛的遗传和物理αS 相互作用图谱不仅将αS连接到膜运输蛋白，而且连接到 RNA结合蛋白（RBP）的数量惊人。然而，虽然RBP失调和损失， RNA内稳态的变化显然是神经退行性变的重要因素， αS和RBPs之间的联系至今仍是难以捉摸的。我们最近发现αS可以干扰RNA 通过直接相互作用和破坏mRNA去帽机制， 加工体，负责mRNA周转的无膜核糖核蛋白复合物。 αS与神经元中P体的脱帽蛋白强烈相互作用。重要的是， （N-末端）αS区负责与膜和P-体蛋白结合。这设置 这是一种二分关系，膜上的改变可以直接影响基因， 通过在膜和胞质间重新分配αS进行调节。上 基于我们在人类iPSC神经元和死后脑中的发现，我们假设αS 穿梭于细胞膜和P-小体之间，一旦积累到毒性水平，就会破坏P-小体。 体成分和mRNA周转。模式生物和人类遗传学分析也 支持P体途径在调节αS毒性和PD风险中的因果影响。这里我们 首先，我们将通过测量大范围的P体扰动来严格测试这些联系。 突触核蛋白病模型、死后脑和小鼠模型，并评估 P体基因对神经毒性的影响。其次，我们将研究哪些特定的mRNA转录本和 mRNA的亚类受到αS积累或突变的影响。最后，我们将调查 αS如何调节完全体外重建系统中的脱帽酶学和组成。 我们预计，这项研究将揭示，RNA稳态破坏是路易的一个关键方面， 研究ADRD的发病机制和激发新的治疗策略。

Neuronal aggregation of the protein alpha-synuclein (αS) in Lewy bodies is a hallmark of key Alzheimer Disease and Related Disorders (ADRDs) including Lewy Body Dementia (LBD), Parkinson’s disease with dementia (PDD) and mixed AD/LB dementia. Collectively these disorders affect millions of US citizens. Understanding mechanisms of αS toxicity thus holds key import for understanding and treating ADRD. αS reversibly associates with cellular membranes in neurons and this interaction is clearly important for toxicity, but the underlying mechanisms remain unclear. Moreover, αS is also highly abundant in the cytosol. What αS is doing in different cellular compartments and how this may be relevant to neurotoxicity when αS abnormally accumulates in ADRD remains unknown. Our previous extensive genetic and physical αS interaction mapping connected αS not only to membrane trafficking proteins but also to a surprising number of RNA-binding proteins (RBPs). However, while RBP dysregulation and loss of RNA homeostasis are clearly important contributors to neurodegeneration in general, a direct link between αS and RBPs was elusive until now. We recently found that αS can perturb RNA homeostasis by directly interacting with and disrupting the mRNA decapping machinery found in Processing Bodies, membraneless ribonucleoprotein complexes responsible for mRNA turnover. αS strongly interacts with decapping proteins of P-bodies in neurons. Importantly, the exact same (N-terminus) αS region is responsible for binding to membranes and to P-body proteins. This sets up a dichotomous relationship whereby alterations at the membrane can directly affect gene regulation through redistributing αS between membrane and cytosolic compartments. On the basis of our findings in human iPSC neurons and postmortem brain, we hypothesize that αS shuttles between membranes and P-bodies and, upon accumulation to toxic levels, disrupts P- body composition and mRNA turnover. Model organism and human genetics analyses also support a causal influence of the P-body pathway in modulating αS toxicity an PD risk. Here, we will, first, rigorously test these connections by measuring P-body perturbations in a wide-range of synucleinopathy models, postmortem brain and mouse models and assess the direct impact of P-body genes on neurotoxicity. Second, we will investigate which specific mRNA transcripts and subclasses of mRNAs are impacted by αS accumulation or mutation. Finally, we will investigate how αS modulates decapping enzymology and composition in a fully in vitro reconstituted system. We anticipate that this study will reveal that RNA homeostasis disruption is a key aspect of Lewy body disease pathogenesis and motivate new treatment strategies for ADRD.