Bai Guang, Cheung Iris, Shulha Hennady P, Coelho Joana E, Li Ping, Dong Xianjun, Jakovcevski Mira, Wang Yumei, Grigorenko Anastasia, Jiang Yan, Hoss Andrew, Patel Krupal, Zheng Ming, Rogaev Evgeny, Myers Richard H, Weng Zhiping, Akbarian Schahram, Chen Jiang-Fan
Department of Neural and Pain Sciences, University of Maryland Dental School, Baltimore, MD 21201, USA.
Brudnick Neuropsychiatric Research Institute.
Hum Mol Genet. 2015 Mar 1;24(5):1441-56. doi: 10.1093/hmg/ddu561. Epub 2014 Dec 5.
To investigate epigenetic contributions to Huntington's disease (HD) pathogenesis, we carried out genome-wide mapping of the transcriptional mark, trimethyl-histone H3-lysine 4 (H3K4me3) in neuronal nuclei extracted from prefrontal cortex of HD cases and controls using chromatin immunoprecipitation followed by deep-sequencing. Neuron-specific mapping of the genome-wide distribution of H3K4me3 revealed 136 differentially enriched loci associated with genes implicated in neuronal development and neurodegeneration, including GPR3, TMEM106B, PDIA6 and the Notch signaling genes hairy and enhancer of split 4 (HES4) and JAGGED2, supporting the view that the neuronal epigenome is affected in HD. Importantly, loss of H3K4me3 at CpG-rich sequences on the HES4 promoter was associated with excessive DNA methylation, reduced binding of nuclear proteins to the methylated region and altered expression of HES4 and HES4 targeted genes MASH1 and P21 involved in striatal development. Moreover, hypermethylation of HES4 promoter sequences was strikingly correlated with measures of striatal degeneration and age-of-onset in a cohort of 25 HD brains (r = 0.56, P = 0.006). Lastly, shRNA knockdown of HES4 in human neuroblastoma cells altered MASH1 and P21 mRNA expression and markedly increased mutated HTT-induced aggregates and cell death. These findings, taken together, suggest that epigenetic dysregulation of HES4 could play a critical role in modifying HD disease pathogenesis and severity.
为了研究表观遗传学对亨廷顿舞蹈病（HD）发病机制的影响，我们利用染色质免疫沉淀结合深度测序技术，对HD病例和对照者前额叶皮质提取的神经元细胞核中的转录标记三甲基组蛋白H3赖氨酸4（H3K4me3）进行了全基因组定位。全基因组范围内H3K4me3分布的神经元特异性定位揭示了136个差异富集位点，这些位点与参与神经元发育和神经退行性变的基因相关，包括GPR3、TMEM106B、PDIA6以及Notch信号基因毛状分裂增强子4（HES4）和锯齿蛋白2（JAGGED2），支持了HD中神经元表观基因组受影响的观点。重要的是，HES4启动子富含CpG序列处H3K4me3的缺失与DNA过度甲基化、核蛋白与甲基化区域结合减少以及参与纹状体发育的HES4及其靶向基因MASH1和P21的表达改变有关。此外，在25例HD脑样本队列中，HES4启动子序列的高甲基化与纹状体变性程度和发病年龄显著相关（r = 0.56，P = 0.006）。最后，在人神经母细胞瘤细胞中通过短发夹RNA敲低HES4改变了MASH1和P21 mRNA的表达，并显著增加了突变型亨廷顿蛋白（HTT）诱导的聚集体和细胞死亡。综上所述，这些发现表明HES4的表观遗传失调可能在改变HD疾病发病机制和严重程度方面起关键作用。
