Transcription profiling of striatal samples from 4 CHL2 Q150/Q150 mutant mice and 4 age-matched wild-type mice to investigate the study of huntingtin toxicity and its remedy in model systems

Achieving a mechanistic understanding of disease and initiating preclinical therapeutic trials necessitate the study of huntingtin toxicity and its remedy in model systems. To allow the engagement of appropriate experimental paradigms, Huntington's disease (HD) models need to be validated in terms of how they recapitulate a particular aspect of human disease. In order to examine transcriptome-related effects of mutant huntingtin, we compared striatal mRNA profiles from seven genetic mouse models of disease to that of postmortem human HD caudate using microarray analysis. Transgenic models expressing short N-terminal fragments of mutant huntingtin (R6/1 and R6/2 mice) exhibited the most rapid effects on gene expression, consistent with previous studies. Although changes in the brains of knock-in models of HD took longer to appear, 15-month and 22-month CHL2Q150/Q150, 18-month HdhQ92/Q92 and 2-year-old YAC128 animals also exhibited significant HD-like mRNA signatures. When the affected genes were compared across models, a robust concordance was observed. Importantly, changes concordant across multiple lines mice were also in excellent agreement with the mRNA changes seen in human HD caudate. Although it was expected that the expression of full-length huntingtin transprotein might result in unique gene expression changes compared to those caused by expression of an N-terminal huntingtin fragment, no discernable differences between full-length and fragment models were detected. There was, however, an overall concordance between transcriptomic signature and disease stage. We thus conclude that the transcriptional changes of HD can be modelled in several available lines of transgenic mice, comprising lines expressing both N-terminal and full-length mutant huntingtin proteins. The combined analysis of mouse and human HD transcriptomes provides an important chronology of mutant huntingtin's gene expression effects. Experiment Overall Design: Striatal samples from 4 CHL2 Q150/Q150 mutant mice and 4 age-matched wild-type mice.要实现对疾病的机制性认知并启动临床前治疗试验，必须在模型系统中开展亨廷顿蛋白（huntingtin）毒性及其干预策略的研究。为采用恰当的实验范式，亨廷顿病（Huntington's disease, HD）模型需根据其重现人类疾病特定病理特征的能力完成验证。为探究突变型亨廷顿蛋白的转录组相关效应，本研究通过微阵列分析（microarray analysis），将7种疾病遗传小鼠模型的纹状体（striatal）mRNA表达谱与死后人类HD尾状核（caudate）的mRNA表达谱进行了对比。表达突变型亨廷顿蛋白N端短片段的转基因模型（transgenic models，R6/1与R6/2小鼠）的基因表达变化最为迅速，这与既往研究结果一致。尽管HD敲入模型（knock-in models）的脑内变化出现得更为迟缓，但15月龄、22月龄的CHL2Q150/Q150小鼠，18月龄的HdhQ92/Q92小鼠以及2岁龄的YAC128小鼠同样呈现出显著的HD样转录组特征。对不同模型的差异表达基因进行跨品系比较后，可观察到高度一致的表达模式。值得注意的是，多个小鼠品系共有的表达变化，与人类HD尾状核中检测到的mRNA表达变化同样契合度极佳。尽管此前曾推测，相较于突变型亨廷顿蛋白N端片段的表达，全长突变型亨廷顿蛋白的表达可能会引发独特的基因表达变化，但本研究并未在全长模型与片段模型之间检测到可辨识的差异。不过，转录组特征与疾病病程阶段整体存在显著一致性。因此本研究得出结论：HD的转录组变化可在多种现有的转基因小鼠模型中复现，这些模型既涵盖表达N端片段的品系，也包含表达全长突变型亨廷顿蛋白的品系。小鼠与人类HD转录组的联合分析，为突变型亨廷顿蛋白的基因表达效应提供了重要的时间序列特征。实验整体设计：采集4只CHL2Q150/Q150突变型小鼠与4只同月龄野生型小鼠的纹状体样本。