Pathobiology of Neurodegeneration in C9ORF72 repeat expansion

在这项题为“C9orf72重复扩张中神经退行性变的病理生物学”的P01提案更新中，我们寻求改善C9orf72相关的肌萎缩侧索硬化症(ALS)和额颞部痴呆(FTD)患者的诊断和预后。我们的集成项目和核心将通过确定“c9ALS/FTD”的治疗目标和生物标记物来实现这一点，并继续我们富有成效的努力，以阐明C9orf72基因中G4C2重复扩张导致神经退化的机制。我们组建了一支世界级的研究团队，他们拥有神经学、遗传学、神经病理学、“组学”、疾病建模、生物标记物和生物信息学方面的专业知识，并密切合作，拥有所有资源。我们在确定支持c9ALS/FTD的病理机制方面取得的重大进展导致发现，从扩展的G4C2重复序列非典型地翻译的聚(GR)蛋白与c9ALS/FTD患者的神经退行性变相关，并导致小鼠神经元丢失，并且聚(GR)诱导应激颗粒的形成并损害其分解。后者可能解释了在C9ALS/FTD中观察到的核质运输缺陷，因为我们的发现是核质运输因子异常地招募到应激颗粒。在拟议的项目中，我们将在这些令人振奋的发现的基础上，解决需要答案的新问题，以开发针对c9ALS/FTD的有效治疗方法。事实上，分别使用下一代质谱学和单核RNA测序对c9ALS患者和(G4C2)149小鼠的脑组织进行深层蛋白质组学和转录图谱分析，将发现代表c9ALS目标路径的蛋白质和基因网络。此外，通过询问重复靶向反义寡核苷酸(ASO)处理的(G4C2)149小鼠和C9ALS患者来源的神经元培养的蛋白质组和转录组，我们将识别对治疗有反应的蛋白质共表达模块和中心蛋白，从而代表潜在的治疗靶点和候选生物标记物。后者代表着一种迫切的需求，因为由于缺乏帮助ALS早期诊断、预测疾病进展和确认靶点参与的生物标记物，潜在ALS治疗的开发和测试已经严重受阻。为了使所有三个研究项目都能有效地实现他们的目标，研究中心将收集C9ALS患者的生物液和脑组织，这也将有助于分析和整合数据，以及验证结果。总体而言，我们的多学科、协同研究将提高我们对C9orf72相关神经退行性变的理解，识别潜在的生物标志物和治疗靶点，并为C9ALS领域开发全面的脑和生物流体资源。

In this P01 proposal renewal entitled “Pathobiology of Neurodegeneration in C9orf72 Repeat Expansion”, we seek to improve the diagnosis of and prognosis for patients suffering from C9orf72-associated amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Our integrated Projects and Cores will accomplish this by identifying therapeutic targets and biomarkers for “c9ALS/FTD” and continuing with our productive endeavors to elucidate the mechanisms by which G4C2 repeat expansions in the C9orf72 gene cause neurodegeneration. We have assembled a world-class team of investigators with expertise in neurology, genetics, neuropathology, “-omics”, disease modeling, biomarkers and bioinformatics that have worked closely together and have all resources in place. Our significant progress to determine the pathomechanisms underpinning c9ALS/FTD has led to the discoveries that poly(GR) proteins atypically translated from expanded G4C2 repeats correlate with neurodegeneration in c9ALS/FTD patients and cause neuronal loss in mice, and that poly(GR) induces the formation of stress granules and impairs their disassembly. The latter may account for the observed nucleocytoplasmic transport defects in c9ALS/FTD given our finding that nucleocytoplasmic transport factors are aberrantly recruited to stress granules. In the proposed projects, we will build upon these exciting findings and tackle new questions in need of answers in order to develop effective treatments for c9ALS/FTD. Indeed, deep proteomic and transcriptomic profiling, respectively, using next-generation mass spectrometry and single-nucleus RNA sequencing of brain tissues from c9ALS patients and (G4C2)149 mice will uncover protein and gene networks that represent target pathways for c9ALS. Furthermore, by interrogating the proteome and transcriptome of (G4C2)149 mice and c9ALS patient-derived neuronal cultures treated with repeat-targeting antisense oligonucleotides (ASO), we will identify protein co-expression modules and hub proteins that respond to treatment and thus represent potential therapeutic targets and candidate biomarkers. The latter represent a critical need given that the development and testing of potential ALS treatments have been seriously hampered by the lack of biomarkers to aid in the early diagnosis of ALS, to forecast disease progression, and to confirm target engagement. To enable all three research projects to effectively achieve their goals, biofluids and brain tissues from c9ALS patients will be collected by the research cores, which will also assist with analyzing and integrating data, as well as validating findings. Overall, our multi-disciplinary, synergistic studies will improve our understanding of C9orf72-related neurodegeneration, identify potential biomarkers and therapeutic targets, and develop a comprehensive brain and biofluid resource for the c9ALS field.