ABSTRACT

Ten-Eleven Translocation (TET) proteins convert 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) leading to a dynamic epigenetic state of DNA that can influence transcription and chromatin organization. While TET proteins interact with complexes involved in transcriptional repression and activation, the overall understanding of the molecular mechanisms involved in TET-mediated regulation of gene expression still remains limited. Here, we show that TET proteins interact with the chromatin remodelling protein lymphoid-specific helicase (LSH/HELLS) in vivo and in vitro. In mouse embryonic fibroblasts (MEFs) and embryonic stem cells (ESCs) knock out of Lsh leads to a significant reduction of 5-hydroxymethylation amount in the DNA. Whole genome sequencing of 5hmC in wild-type versus Lsh knock-out MEFs and ESCs showed that in absence of Lsh, some regions of the genome gain 5hmC while others lose it, with mild correlation with gene expression changes. We further show that differentially hydroxymethylated regions did not completely overlap with differentially methylated regions indicating that changes in 5hmC distribution upon Lsh knock-out are not a direct consequence of 5mC decrease. Altogether, our results suggest that LSH, which interacts with TET proteins, contributes to the regulation of 5hmC levels and distribution in MEFs and ESCs.

摘要

十一十一易位 (TET) 蛋白将 5-甲基胞嘧啶 (5mC) 转化为 5-羟甲基胞嘧啶 (5hmC)，从而导致 DNA 的动态表观遗传状态，从而影响转录和染色质组织。虽然 TET 蛋白与参与转录抑制和激活的复合物相互作用，但对 TET 介导的基因表达调控所涉及的分子机制的总体理解仍然有限。在这里，我们显示 TET 蛋白在体内和体外与染色质重塑蛋白淋巴特异性解旋酶 (LSH/HELLS) 相互作用。在小鼠胚胎成纤维细胞 (MEF) 和胚胎干细胞 (ESC) 中敲除Lsh导致DNA中5-羟甲基化量显着减少。野生型与Lsh敲除 MEF 和 ESC 中 5hmC 的全基因组测序表明，在没有Lsh的情况下，基因组的某些区域获得 5hmC 而其他区域则失去它，与基因表达变化有轻微相关性。我们进一步表明差异羟甲基化区域没有与差异甲基化区域完全重叠，表明Lsh敲除后 5hmC 分布的变化不是 5mC 减少的直接结果。总之，我们的结果表明，与 TET 蛋白相互作用的 LSH 有助于调节 MEF 和 ESC 中的 5hmC 水平和分布。