RNA Granules in Cerebellar Neurodegeneration

根据世卫组织的估计，神经退行性疾病代表着不断增加的社会和经济负担 这表明，到2040年，它们将取代癌症，成为第二大死亡原因。在神经退行性变中 在疾病研究中，已经发现了大量的途径，但它们与 人类各自的疾病很难证明，靶向通路仍然很困难。这个 拟议的工作将描述遗传性脊髓小脑性共济失调2型(Sca2)的应激颗粒(Sgs)。 影响小脑浦肯野神经元(PNS)和小脑其他神经元的神经退行性疾病， 脑干和大脑。SCA2的原因是ATXN2基因的CAG功能增强 从而在ataxin-2中产生扩展的聚谷氨酰胺(PolyQ)。此前已知ATXN2具有以下功能 基于其与多种RNA结合蛋白(RBPs)相互作用的mRNA代谢，包括 A2BP1/RBFOX1、DDX6、PABP1、TDP-43、FUS。我们现在已经证明了突变体ATXN2与 SG蛋白Staufen1，这种相互作用对SGS有特定的影响。Staufen表达式(但不是DDX6或 PABPC1)随着ATXN2突变而增加，我们还确定了特定的下游后果 这种相互作用对直接与Staufen相互作用的SG mRNAs丰度的影响。建议的目标是 研究旨在从机制上表征为什么Staufen的表达随着ATXN2突变而增加，以 鉴定SCA2患者成纤维细胞和神经元中SCA2 SGS的蛋白质组和mRNA组成 在sca2转基因小鼠中。通过这项工作确定的SG元素可能被用于治疗 治疗SCA2。提出了三个具体的目标：1)我们将评估突变的ATXN2对蛋白质的抑制作用 自噬是Staufen过表达的一个原因，并将表征Sca2 SG的形成速度、半衰期、 以及超分辨显微镜下的超微结构，以及使用纯化的SGS的sca2 SG转录本。 2)我们将用FISH方法在培养的SCA2神经元和小脑片中定位sca2 SG mRNAs。 SCA2小鼠。3)我们将测定sca2小鼠的运动和神经生理表型。 对于Staufen，单倍体不足，并将在成像的同时记录Purkinje细胞的激发频率 TIA1阳性SGS和钙丰度。这将确定是否存在异常的SG贩运/本地化 与SCA2小鼠的PC生理异常有关，这取决于Staufen的表达。拟议中的工作 将阐明SGS在神经退行性变中的作用，并将有助于确定新的途径 SCA2和其他退行性共济失调的治疗

Neurodegenerative diseases represent an ever-increasing societal and economic burden with WHO estimates indicating that they will replace cancer as the 2nd leading cause of death by 2040. In neurodegenerative disease research, a wealth of pathways has been uncovered, but their direct and primary relevance to the respective human disease has been difficult to prove and targeting of pathways has remained difficult. The proposed work will characterize stress granules (SGs) in spinocerebellar ataxia type 2 (SCA2), a hereditary neurodegenerative disease affecting cerebellar Purkinje neurons (PNs) and other neurons in the cerebellum, brainstem and cerebrum. The cause of SCA2 is a gain-of-function CAG expansion in the ATXN2 gene resulting in an expanded polyglutamine (polyQ) in ataxin-2. ATXN2 was previously known to have functions in mRNA metabolism based on its interactions with multiple RNA binding proteins (RBPs) including A2BP1/RBFOX1, DDX6, PABP1, TDP-43, FUS. We have now demonstrated that mutant ATXN2 interacts with the SG protein Staufen1, and this interaction has specific effects on SGs. Staufen expression (but not DDX6 or PABPC1) is increased with ATXN2 mutation, and we have also identified specific downstream consequences of this interaction on the abundance of SG mRNAs directly interacting Staufen. The objective of the proposed research is to characterize mechanistically why Staufen expression increases with ATXN2 mutation, to characterize the proteomic and mRNA composition of SCA2 SGs in SCA2 patient fibroblasts and neurons and in SCA2 transgenic mice. SG elements that are identified by this work might be exploited therapeutically for treating SCA2. Three specific aims are proposed: 1) We will evaluate mutant ATXN2 inhibition of protein autophagy as a reason for staufen overexpression, and will characterize SCA2 SG rate of formation, half-life, and superstructure using superresolution microscopy, as well as SCA2 SG transcriptomes using purified SGs. 2) We will conduct FISH to localize SCA2 SG mRNAs in cultured SCA2 neurons and in cerebellar slices of SCA2 mice. 3) We will determine SCA2 mouse motor and neurophysiological phenotypes in SCA2 mice haploinsufficient for Staufen, and will record Purkinje cell firing frequencies simultaneously with imaging for TIA1 positive SGs and calcium abundance. This will determine whether abnormal SG trafficking/localization associates with abnormal PC physiology in SCA2 mice, depending on Staufen expression. The proposed work will clarify the role for SGs in neurodegeneration and will aid in the identification of new avenues towards treatments of SCA2 and other degenerative ataxias