1] Systems Biology Center, National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20892, USA [2] Current address: Department of Native Hawaiian Health, John A. Burns School of Medicine, University of Hawai`i at Manoa, Honolulu, HI 96813, USA.
Cell Res. 2013 Nov;23(11):1256-69. doi: 10.1038/cr.2013.110. Epub 2013 Aug 13.
Although the function of DNA methylation in gene promoter regions is well established in transcriptional repression, the function of the evolutionarily conserved widespread distribution of DNA methylation in gene body regions remains incompletely understood. Here, we show that DNA methylation is enriched in included alternatively spliced exons (ASEs), and that inhibition of DNA methylation results in aberrant splicing of ASEs. The methyl-CpG-binding protein MeCP2 is enriched in included ASEs, particularly those that are also highly methylated, and inhibition of DNA methylation disrupts specific targeting of MeCP2 to exons. Interestingly, ablation of MeCP2 results in increased histone acetylation and aberrant ASE-skipping events. We further show that inhibition of histone deacetylase (HDAC) activity leads to exon skipping that shows a highly significant degree of overlap with that caused by MeCP2 knockdown. Together, our data indicate that intragenic DNA methylation operates in exon definition to modulate alternative RNA splicing and can enhance exon recognition via recruitment of the multifunctional protein MeCP2, which thereby maintains local histone hypoacetylation through the subsequent recruitment of HDACs.
尽管 DNA 甲基化在基因启动子区域的转录抑制功能已得到充分证实，但在基因体区域广泛分布的进化保守的 DNA 甲基化的功能仍不完全清楚。在这里，我们表明 DNA 甲基化在包含的选择性剪接外显子（ASE）中富集，并且 DNA 甲基化的抑制导致 ASE 的异常剪接。富含甲基化CpG 结合蛋白 MeCP2 的包含 ASE，特别是那些也高度甲基化的 ASE，并且 DNA 甲基化的抑制破坏了 MeCP2 对外显子的特定靶向。有趣的是，MeCP2 的缺失导致组蛋白乙酰化增加和 ASE 跳跃事件异常。我们进一步表明，组蛋白去乙酰化酶（HDAC）活性的抑制导致外显子跳跃，这与 MeCP2 敲低引起的外显子跳跃有高度显著的重叠。总之，我们的数据表明，基因内 DNA 甲基化在调节选择性 RNA 剪接的外显子定义中起作用，并可通过募集多功能蛋白 MeCP2 增强外显子识别，从而通过随后募集 HDAC 维持局部组蛋白低乙酰化。
