Dysregulation of inhibitory synapse by poly-GR in C9ORF72-ALS/FTD

该项目的目标是了解由沙门氏菌引起的抑制性突触的失调。 C9ORF72连锁的肌萎缩侧索硬化症(ALS)和额颞部退行性变中的Poly-GR (FTD)。C9ORF72基因的六核苷酸重复扩增是最常见的遗传 肌萎缩侧索硬化症和FTD的原因。一个潜在的致病机制是异常堆积。 由重复相关非AUG(RAN)翻译产生的二肽重复(DPR)蛋白在 所有六个读框(PolyGA、PolyGR、PolyPA、PolyPR和PolyPG)都是正义和 反义RNA。一系列证据表明，某些形式的DPR蛋白，特别是GR 和PR，可以诱导几个分子通路的失调，包括应激颗粒 功能障碍、核质转运缺陷、内质网稳态改变等。这些是如何 分子缺陷对神经元功能的影响尚不清楚。 越来越多的证据表明，突触密度和功能发生了变化 在神经退行性疾病中出现显著的神经元死亡之前。的发展。 过度兴奋是一种众所周知的现象。一个看似合理的机制是 兴奋活性与抑制活性的比率(E/I失衡)。我们的初步数据确定了特定的 抑制突触形成和抑制突触形成所必需的骨架蛋白-的减少 C9ORF72-ALS/FTD患者IPSC神经元和多糖原代神经元的功能 表情。我们现在建议对结构和电生理功能障碍进行表征。 并破译Poly-GR导致这种情况的分子机制 通过将不同组学技术与分子和细胞方法相结合而产生的缺陷。我们 目的用邻位标记蛋白质组学方法鉴定神经元中GR相互作用蛋白。 通过高通量测序发现GR诱导的转录变化 进一步研究其对GR介导突触作用的基因/途径 监管失调。这个项目在理解分子方面迈出了重要的第一步 ALS和FTD患者神经元功能障碍的机制。由此产生的分子洞察力 这项研究将有助于了解该病的病因，并开发新的 治疗靶点。

The goal of the project is to understand the dysregulation of inhibitory synapse caused by poly-GR in C9ORF72-linked amyotrophic lateral sclerosis (ALS) and frontotemporal degeneration (FTD). Hexanucleotide repeat expansion in the C9ORF72 gene is the most common genetic cause of both ALS and FTD. One potential pathogenic mechanism is the aberrant accumulation of dipeptide repeat (DPR) proteins produced by repeat-associated non-AUG (RAN) translation in all six reading frames (poly-GA, poly-GR, poly-PA, poly-PR and poly-PG) of both sense and antisense RNAs. Lines of evidence indicate that some forms of the DPR proteins, particularly GR and PR, can induce dysregulation of several molecular pathways, including stress granule dysfunction, nucleocytoplasmic transport defects, altered ER homeostasis, et al. How these molecular deficits influence neuronal functions remains understudied. Accumulating evidence indicated that changes of synapse density and function occurs prior to significant neuronal death in neurodegenerative diseases. The development of hyperexcitability is a well-known phenomenon. One plausible mechanism is the alterations in the ratio of excitatory to inhibitory activity (E/I imbalance). Our preliminary data identified specific reduction of gephyrin clustering, a scaffold protein essential for inhibitory synapse formation and function, in C9ORF72-ALS/FTD patient iPSC-neurons and in primary neurons with poly-GR expression. We now propose to characterize the structure and electrophysiological dysfunction of the inhibitory synapse, and to decipher the molecular mechanism how poly-GR causes such defects by combining different –omics techniques with molecular and cellular approaches. We aim to identify GR-interacting proteins in neurons using the proximity-labeling proteomics and GR-induced transcriptomic changes by high-throughput sequencing, which will reveal candidate genes/pathways for further mechanistic study of their contribution to GR-mediated synaptic dysregulation. This project makes an important first step toward understanding the molecular mechanisms of neuronal dysfunction in ALS and FTD patients. The molecular insights resulting from this study will help understanding the etiology of the disease and developing novel therapeutic targets.