Transcription profiling of mouse striatum from 3- and 18-month-old Q92 vs. control animals

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 6 Q92 mutant mice (3 3-month-old and 3 18-month-old) and 6 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，亟需在模式生物系统中开展亨廷顿蛋白（huntingtin）毒性及其干预手段的相关研究。为采用恰当的实验范式开展研究，亨廷顿病（Huntington's disease, HD）模型需依据其重现人类疾病特定病理特征的能力进行验证。 为探究突变亨廷顿蛋白引发的转录组相关效应，本研究通过微阵列分析（microarray analysis），将7种遗传性疾病小鼠模型的纹状体mRNA表达谱与死后人类亨廷顿病患者尾状核组织的表达谱进行了对比。 表达突变亨廷顿蛋白N端短片段的转基因模型（transgenic models）——R6/1与R6/2小鼠——在基因表达层面呈现出最快速的变化，这与既往研究结果一致。尽管亨廷顿病敲入模型（knock-in models）脑部的表达变化出现得更晚，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mRNA表达特征。 对不同模型的差异表达基因进行跨模型比对后，观察到高度一致的表达模式。尤为重要的是，多个小鼠品系中共存的表达变化，与人类亨廷顿病尾状核组织中观测到的mRNA表达变化也高度吻合。尽管此前曾推测，相较于突变亨廷顿蛋白N端片段引发的基因表达变化，全长亨廷顿蛋白的表达可能会产生独特的基因表达谱改变，但本研究未检测到全长模型与片段模型之间存在可辨识的差异。不过，转录组特征与疾病病程整体呈现出良好的一致性。 据此我们认为，亨廷顿病的转录组变化可在多种现有的转基因小鼠模型中重现，这些模型涵盖了表达突变亨廷顿蛋白N端片段与全长蛋白的品系。对小鼠与人类亨廷顿病转录组的联合分析，为阐明突变亨廷顿蛋白的基因表达效应提供了重要的时间序列证据。 实验总体设计：采集6只Q92突变小鼠（3只3月龄、3只18月龄）以及6只同月龄野生型小鼠的纹状体组织样本。