Yamanaka Tomoyuki, Miyazaki Haruko, Oyama Fumitaka, Kurosawa Masaru, Washizu Chika, Doi Hiroshi, Nukina Nobuyuki
Laboratory for Structural Neuropathology, RIKEN Brain Science Institute, Saitama, Japan.
EMBO J. 2008 Mar 19;27(6):827-39. doi: 10.1038/emboj.2008.23. Epub 2008 Feb 21.
In Huntington's disease (HD), mutant Huntingtin, which contains expanded polyglutamine stretches, forms nuclear aggregates in neurons. The interactions of several transcriptional factors with mutant Huntingtin, as well as altered expression of many genes in HD models, imply the involvement of transcriptional dysregulation in the HD pathological process. The precise mechanism remains obscure, however. Here, we show that mutant Huntingtin aggregates interact with the components of the NF-Y transcriptional factor in vitro and in HD model mouse brain. An electrophoretic mobility shift assay using HD model mouse brain lysates showed reduction in NF-Y binding to the promoter region of HSP70, one of the NF-Y targets. RT-PCR analysis revealed reduced HSP70 expression in these brains. We further clarified the importance of NF-Y for HSP70 transcription in cultured neurons. These data indicate that mutant Huntingtin sequesters NF-Y, leading to the reduction of HSP70 gene expression in HD model mice brain. Because suppressive roles of HSP70 on the HD pathological process have been shown in several HD models, NF-Y could be an important target of mutant Huntingtin.
在亨廷顿舞蹈症（HD）中，含有扩展多聚谷氨酰胺片段的突变型亨廷顿蛋白在神经元中形成核聚集体。几种转录因子与突变型亨廷顿蛋白的相互作用，以及HD模型中许多基因表达的改变，意味着转录失调参与了HD的病理过程。然而，确切机制仍不清楚。在此，我们表明突变型亨廷顿蛋白聚集体在体外和HD模型小鼠脑中与NF-Y转录因子的组分相互作用。使用HD模型小鼠脑裂解物进行的电泳迁移率变动分析表明，NF-Y与NF-Y靶标之一HSP70的启动子区域的结合减少。RT-PCR分析显示这些脑中HSP70表达降低。我们进一步阐明了NF-Y对培养神经元中HSP70转录的重要性。这些数据表明，突变型亨廷顿蛋白隔离NF-Y，导致HD模型小鼠脑中HSP70基因表达降低。因为在几种HD模型中已经显示HSP70对HD病理过程具有抑制作用，所以NF-Y可能是突变型亨廷顿蛋白的一个重要靶标。
