Human huntingtin derived from YAC transgenes compensates for loss of murine huntingtin by rescue of the embryonic lethal phenotype
Human huntingtin derived from YAC transgenes compensates for loss of murine huntingtin by rescue of the embryonic lethal phenotype
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DOI：
10.1093/hmg/5.12.1875
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发表时间：
1996-12-01
影响因子：
3.5
通讯作者：
Hayden, MR
中科院分区：
文献类型：
--
作者：
Hodgson, JG;Smith, DJ;Hayden, MR
亨廷顿病（HD）是由一种新基因外显子1 CAG三核苷酸重复扩增引起的。HD蛋白（亨廷顿蛋白）在早期胚胎发育中起着关键作用，因为纯合子靶向破坏小鼠HD基因会导致胚胎在7.5天死亡。因此，为了通过基于转基因的亨廷顿蛋白表达来挽救这种表型，必须在适当的细胞发育早期表达该蛋白。由于已知基于YAC的转基因以适当的时间和组织特异性方式进行调节，我们试图通过培养表达人类亨廷顿蛋白的YAC转基因小鼠与小鼠杂合子进行靶向破坏来挽救胚胎致病性。我们为被破坏的小鼠HD基因产生了可存活的纯合子，但表达了来自YAC的人类亨廷顿蛋白。这一结果清楚地表明，基于YAC转基因的亨廷顿蛋白表达发生在妊娠7.5天之前。此外，我们发现在YAC转基因小鼠中，人类亨廷顿蛋白的表达遵循与小鼠内源性蛋白相同的组织分布和亚细胞定位模式，表达水平可以达到内源性蛋白的2-3倍。这表明，在其天然启动子的影响下，人类亨廷顿蛋白尽管与小鼠蛋白存在差异，但在小鼠背景下仍具有功能，可以弥补小鼠蛋白的缺失。这些结果表明，YAC转基因方法是一种特别有前途的途径，可以产生与CAG扩增相关的疾病的动物模型。
Huntington disease (HD) is caused by expansion of a CAG trinucleotide repeat in exon 1 of a novel gene. The HD protein (huntingtin) plays a critical role in early embryonic development since homozygous targeted disruption of the murine HD gene results in embryonic lethality by day 7.5. To rescue this phenotype by transgene based huntingtin expression it is therefore essential to express the protein early enough in development in the appropriate cells. Since YAC based transgenes are known to be regulated in an appropriate temporal and tissue-specific manner, we sought to rescue the embryonic lethality by breeding YAC transgenic mice expressing human huntingtin with mice heterozygous for the targeted disruption. We generated viable offspring homozygous for the disrupted murine HD gene but expressing human huntingtin derived from the YAC. This result clearly shows that YAC transgene based expression of huntingtin occurs prior to 7.5 days gestation. Additionally, we show that human huntingtin expression in YAC transgenic mice follows an identical tissue distribution and subcellular localisation pattern as that of the murine endogenous protein and that expression levels of 2-3 times endogenous can be achieved. This shows that human huntingtin under the influence of its native promoter, despite differences to the murine protein, is functional in a murine background and can compensate for loss of the murine protein. These results show that YAC transgenic approaches are a particularly promising route to producing an animal model for disorders associated with CAG expansion.