Novel mouse genetic models to study modifiers of Huntington’s disease

项目摘要 亨廷顿病（Huntington 'sdisease，HD）是一种常见的常染色体显性遗传性神经退行性疾病 影响了美国3万名患者HD患者通常会经历运动、认知和精神方面的疾病 症状，这是与纹状体和皮质神经元的损失。疾病无情地 在发病后进展，并且患者通常在疾病后约10-20年死于疾病 发病HD是由突变亨廷顿蛋白中编码多聚谷氨酰胺重复的CAG重复扩增引起的 （mHTT）。目前，没有预防HD发作或减缓HD进展的治疗方法。 最近的一项全基因组关联研究（GWAS）确定了几个与HD年龄改变相关的基因座 疾病的发作。鉴定的最重要的基因座在第15染色体中，包括DNA修复酶 称为FAN 1。有趣的是，FAN 1和HD修饰物GWAS中鉴定的另外两个基因（MLH 1和MSH 3） 均与mHTT CAG重复序列在体细胞中的不稳定性有关。然而，目前尚不清楚是否 FAN 1在CAG重复不稳定性中的作用与其作为HD病理学修饰剂的功能有关，包括 行为障碍（自发活动、睡眠障碍）、纹状体和皮质神经元电生理 病理变化和转录失调。 在这个提议中，我们将使用两个HD小鼠模型，Q140小鼠Htt， 敲入模型和具有>120个纯CAG重复的HD的新型人基因组BAC转基因小鼠模型。 后一个模型是第一个显示CAG重复不稳定性的人类mHTT模型，该不稳定性与 行为缺陷和强烈的纹状体选择性转录失调。我们将通过这两个高清 小鼠模型与新的Fan 1/FAN 1遗传模型，以解决以下关键问题：1。减少 内源性小鼠Fan 1水平加速两种HD小鼠模型的发病机制（目的1）？2.做 具有鼠Fan 1-R510 H敲入等位基因的小鼠（相当于人患者来源的有害FAN 1 变异R507 H）显示疾病恶化的影响，类似于Fan 1敲除小鼠（目的2）？和3. 人FAN 1表达升高的遗传小鼠模型（BAC-FAN 1）是否可以改善 两种HD中的行为、电生理、病理和分子（即转录组学）表型 小鼠模型（目标3）？ 我们的研究结果对于揭示大脑中的位置和分子机制至关重要 Fan 1突变体如何在体内改变HD发病机制。此外，我们拥有的鼠标资源 本研究中使用的表型分析平台对未来的研究将是非常宝贵的。 其他HD修饰剂和用于开发靶向HD人类遗传修饰剂的治疗剂，以预防、减缓和/或抑制HD的发生。 或停止HD的进展。

PROJECT SUMMARY Huntington's disease (HD) is one of the most common autosomal dominant neurodegenerative disorders affecting 30,000 patients in the US. HD patients typically experience motor, cognitive and psychiatric symptoms, which is associated with the loss of the striatal and cortical neurons. The disease inexorably progresses after the onset and patients typically succumb to the disease about 10-20 years after disease onset. HD is caused by a CAG repeat expansion, that encodes a polyglutamine repeat, in mutant Huntingtin (mHTT). Currently, there is no treatment to prevent the onset or slow the progression of HD. A recent genome wide association study (GWAS) identified several loci associated with modification of HD age of disease onset. The most significant loci identified were in Chr. 15 and encompasses a DNA repair enzyme called FAN1. Interestingly, FAN1 and two other genes identified in the HD modifier GWAS (MLH1 and MSH3) are all implicated in the instability of mHTT CAG repeat in somatic tissues. However, it is unclear whether FAN1's roles in CAG repeat instability is related to its function as a modifier of HD pathology including behavioral impairment (locomotor activity, sleep disturbance), striatal and cortical neuronal electrophysiological and pathological changes, and transcriptional dysregulation. In this proposal, we will address these critical questions using two HD mouse models, the Q140 murine Htt knockin model and a novel human genomic BAC transgenic mouse model of HD with >120 pure CAG repeats. The latter model is the first human mHTT model that shows CAG repeat instability that is correlated with behavioral deficits, and robust striatum-selective transcriptional dysregulation. We will cross these two HD mouse models with novel Fan1/FAN1 genetic models to address the following key questions: 1. Does reducing endogenous murine Fan1 levels accelerate the pathogenesis in the two HD mouse models (Aim 1)? 2. Do mice with murine Fan1-R510H knockin alleles (equivalent to the human patient-derived, deleterious FAN1 variant R507H) show disease-exacerbating effects, similar to the Fan1 knockdown mice (Aim 2)? and 3. Whether genetic mouse models with elevated expression of human FAN1 (BAC-FAN1) can ameliorate the behavioral, electrophysiological, pathological and molecular (i.e. transcriptomic) phenotypes in the two HD mouse models (Aim 3)? The findings from our study will be crucial to unravel where in the brain and what molecular mechanisms underly how Fan1 mutants modify HD pathogenesis in vivo. Furthermore, the mouse resources we have developed and the phenotyping platforms that will use in this study will be invaluable to future investigations of other HD modifiers and for developing therapeutics to target the HD human genetic modifiers to prevent, slow or stop progression of HD.