Huntington's disease-like 2 is associated with CUG repeat-containing RNA foci
Huntington's disease-like 2 is associated with CUG repeat-containing RNA foci
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DOI：
10.1002/ana.21081
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发表时间：
2007-03-01
影响因子：
11.2
通讯作者：
Margolis, Russell L.
中科院分区：
文献类型：
--
作者：
Rudnicki, Dobrila D.;Holmes, Susan E.;Margolis, Russell L.
目的：亨廷顿病样2(HDL2)是由染色体16q24.3上的CAG/CTG扩增突变引起的。该重复序列在CTG方向上落在连接素-3(IPH3)的可变剪接外显子内。JPH3剪接变异体的存在和CTG重复序列在3‘非翻译区的存在提示，含有扩展的CUG重复序列的转录本可能在HDL2的发病机制中发挥作用，类似于在强直性肌营养不良1型(DM1)中扩展的CUG重复序列的致病作用。因此，本研究的目的是验证在HDL2发病机制中一个RNA功能获得组分的合理性。方法：用原位杂交和免疫组织化学方法研究HDL2、亨廷顿病、DM1和对照组大脑额叶皮质中RNA灶的存在和组成。设计并在人胚胎肾293和HT22细胞中表达了一个含有正常或扩展的CUG重复序列的不可翻译的JPH3转录本，以进一步验证毒性RNA假说。结果：在HDL2皮质和其他脑区的神经元中检测到与DM1灶相似的RNA灶。与DMI相似，病灶与肌盲样蛋白1共定位，与对照组相比，HDL2皮质神经元中的核肌盲样蛋白I减少。在细胞实验中，表达带有扩展的CUG重复序列的JPH3转录本导致与肌样蛋白I共定位的RNA焦点的形成和细胞毒性。解释：这些结果表明RNA毒性可能与HDL2的发病有关。
Objective: Huntington's disease-like 2 (HDL2) is caused by a CAG/CTG expansion mutation on chromosome 16q24.3. The repeat falls, in the CTG orientation, within a variably spliced exon of junctophilin-3 (IPH3). The existence of a JPH3 splice variant with the CTG repeat in 3' untranslated region suggested that transcripts containing an expanded CUG repeat could play a role in the pathogenesis of HDL2, similar to the proposed pathogenic role of expanded CUG repeats in myotonic dystrophy type 1 (DM1). The goal of this study, therefore, was to test the plausibility of an RNA gain-of-function component in the pathogenesis of HDL2.Methods: The presence and composition of RNA foci in frontal cortex from HDL2, Huntington's disease, DM1, and control brains were investigated by in situ hybridization and immunohistochemistry. An untranslatable JPH3 transcript containing either a normal or an expanded CUG repeat was engineered and expressed in human embryonic kidney 293 and HT22 cells to further test the toxic RNA hypothesis. The formation of RNA foci and the extent of cell death were quantified.Results: RNA foci resembling DM1 foci were detected in neurons in HDL2 cortex and other brain regions. Similar to DMI, the foci colocalize with muscleblind-like protein 1, and nuclear muscleblind-like protein I in HDL2 cortical neurons is decreased relative to controls. In cell experiments, expression of a JPH3 transcript with an expanded CUG repeat resulted in the formation of RNA foci that colocalized with muscleblind-like protein I and in cell toxicity.Interpretation: These results imply that RNA toxicity may contribute to the pathogenesis of HDL2.