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

项目总结 摘要亨廷顿病是最常见的常染色体显性遗传性神经退行性疾病之一。 影响了美国的3万名患者。HD患者通常会经历运动、认知和精神障碍 症状，这与纹状体和皮质神经元的丧失有关。这种疾病无情地 发病后进展，患者通常在发病后10-20年内死于该病 开始了。HD是由突变的Huntingtin中编码聚谷氨酰胺重复序列的CAG重复序列扩张引起的 (MHTT)。目前，尚无预防或减缓HD发病或进展的治疗方法。 最近的一项全基因组关联研究发现了几个与HD AGE改变相关的基因座 疾病发作的可能性。发现的最显著的基因座在Chr。15，包含一种DNA修复酶 称为FAN1。有趣的是，FAN1和另外两个在HD修饰物GWAS(MLH1和MSH3)中发现的基因 都与体细胞组织中mHTT CAG重复序列的不稳定性有关。然而，目前还不清楚是否 Fan1的S在CAG重复不稳定中的作用与其作为HD病理修饰物的功能有关，包括 行为障碍(运动、睡眠障碍)、纹状体和皮质神经元电生理 和病理变化，以及转录失调。 在这项提案中，我们将使用两个HD小鼠模型Q140小鼠Htt来解决这些关键问题 Knockin模型和一种新的人类基因组BAC转基因HD小鼠模型，其中&gt；120个纯CAG重复。 后一种模型是第一个显示CAG重复不稳定的人类mHTT模型，与 行为缺陷和强烈的纹状体选择性转录失调。我们将穿过这两个高清 用新的Fan1/FAN1遗传模型解决以下关键问题的小鼠模型：1.减少 内源性小鼠Fan1水平促进两种HD小鼠模型的发病(目标1)？2. 携带小鼠Fan1-R510H敲门等位基因的小鼠(相当于人类患者衍生的有害FAN1 变异体R507H)表现出加重疾病的作用，类似于Fan1基因敲除小鼠(目标2)？和3. 人FAN1高表达的遗传性小鼠模型(BAC-FAN1)是否能改善 两种HD的行为、电生理、病理和分子(即转录)表型 小鼠模型(目标3)？ 我们的研究结果将对揭开大脑的位置和分子机制至关重要 了解Fan1突变体如何在体内改变HD的发病机制。此外，我们拥有的鼠标资源 这项研究中开发的表型分析平台将对未来的研究具有非常重要的价值 其他HD修饰物和开发针对HD人类遗传修饰物的治疗方法以防止、减缓 或者阻止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.