Structure of Triplet Repeat mRNA in Neurodegenerative Disease

三联核苷酸重复扩增突变导致进行性和致命性神经退行性变 疾病如亨廷顿氏病（HD）和脊髓小脑性共济失调2型（SCA 2）。 尽管已经提出了许多机制来解释三联体的病理作用， 重复扩增突变，这些疾病的分子基础仍然难以捉摸。最 研究集中在由CAG编码的扩增的多聚谷氨酰胺蛋白的毒性作用上 重复。然而，三联体重复RNA最近已被证明对神经元有毒， 有助于疾病。这项研究将使用一种新的X射线足迹技术， 活神经元细胞中扩增的亨廷顿蛋白mRNA的异常结构。第一个目标是 确定未应激和应激细胞中正常和扩增RNA的结构， 模拟HD的神经毒性作用。不同三联体重复mRNA的比较将鉴定 容易形成神经毒性RNA结构的序列。第二个目的是研究如何 三联体重复RNA和细胞蛋白质之间的相互作用导致神经毒性。在 此外，将测试结合CAG RNA重复序列的工具化合物阻断CAG RNA重复序列的能力。 异常的mRNA结构。第三个目的是确定三联体的结构是否重复 复合物及其对mRNA相互作用体的影响解释了 三重重复突变。X射线足迹法首次应用于细胞中的mRNA 将mRNAs的三维结构与三联体重复疾病的病理学联系起来， 并确定小分子工具化合物如何破坏活细胞中的这些结构。的 长期目标是确定RNA-蛋白质相互作用的结构特征， 神经毒性，并且可以通过新的疗法来靶向。

Triplet nucleotide repeat expansion mutations cause progressive and lethal neurodegenerative diseases such as Huntington's Disease (HD) and Spinocerebellar ataxia type 2 (SCA2). Although many mechanisms have been proposed to explain the pathological effects of triplet repeat expansion mutations, the molecular basis for these diseases remains elusive. Most research has focused on the toxic effects of expanded polyglutamine proteins encoded by CAG repeats. However, triplet repeat RNA has recently been shown to be toxic to neurons and to contribute to disease. This research will use a new X-ray footprinting technique to visualize the abnormal structure of the expanded huntingtin mRNA in living neuronal cells. The first aim is to determine the structures of normal and expanded RNA in unstressed and stressed cells that mimic the neurotoxic effects of HD. Comparisons of different triplet repeat mRNAs will identify sequences that readily form neurotoxic RNA structures. The second aim is to investigate how interactions between triplet repeat RNA and cellular proteins contribute to neurotoxicity. In addition, a tool compound that binds CAG RNA repeats will be tested for its ability to block abnormal mRNA structures. The third aim is to determine whether the structures of triplet repeat complexes and their effect on the mRNA interactome account for the varied sensitivity of neurons to triplet repeat mutations. This first application of X-ray footprinting to mRNAs in cells will link the three-dimensional structures of mRNAs with the pathology of triplet repeat diseases, and determine how small molecule tool compounds disrupt these structures in live cells. The long-term goal is to identify a structural signature of RNA-protein interactions that predict neurotoxicity and that can be targeted by new therapies.