Stable 5-Hydroxymethylcytosine (5hmC) Acquisition Marks Gene Activation During Chondrogenic Differentiation.
Stable 5-Hydroxymethylcytosine (5hmC) Acquisition Marks Gene Activation During Chondrogenic Differentiation.
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DOI：
10.1002/jbmr.2711
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发表时间：
2016-03
期刊：
影响因子：
--
通讯作者：
Bhutani N
中科院分区：
文献类型：
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作者：
Taylor SE;Li YH;Smeriglio P;Rath M;Wong WH;Bhutani N
DNA甲基化和去甲基化对软骨细胞分化过程中基因表达变化的调控知之甚少。甲基化胞嘧啶(5mC)被Tet蛋白氧化成5-羟甲基胞嘧啶(5hmC)、5-甲酰胞嘧啶(5fC)和5-羧基胞嘧啶(5caC)，最终被未甲基化胞嘧啶(C)取代，即DNA去甲基化。此外，5hmC是稳定的，本身就是一个表观遗传标记。在这里，我们报告了5hmC的全球变化标志着体内和体外的软骨分化。对胚胎11.5天、13.5天和17.5天小鼠肢体发育过程中的胫骨原纤维和生长板的分析表明，分化的软骨细胞中5hmC的水平发生了动态变化。在ATDC5软骨前体细胞系中也观察到类似的5hmC水平升高，同时伴随着Tet蛋白在体外分化过程中的表达增加。TET1在ATDC5中的缺失降低了5hmC的水平并损害了分化，显示了TET1介导的5hmC动力学在软骨分化中的功能作用。对软骨分化早期和晚期富含5hmC序列的全局分析表明，5hmC分布在转录起始点(TSS)之前的基因调控区以及基因体中。在特定的基因亚群中观察到5hmC的稳定增长，包括与软骨发育相关的基因和软骨形成谱系特异性基因。5HmC在调控启动子和增强子区域以及在基因体中的获得与激活的基因密切相关，但不与抑制基因相关，这表明DNA羟甲基化在软骨基因表达中具有潜在的调节作用。
Regulation of gene expression changes during chondrogenic differentiation by DNA methylation and demethylation is little understood. Methylated cytosines (5mC) are oxidized by the ten-eleven-translocation (TET) proteins to 5-hydroxymethylcytosines (5hmC), 5-formylcytosines (5fC) and 5-carboxylcytosines (5caC) eventually leading to a replacement by unmethylated cytosines (C) i.e. DNA demethylation. Additionally, 5hmC is stable and acts as an epigenetic mark by itself. Here, we report that global changes in 5hmC mark chondrogenic differentiation in vivo and in vitro. Tibia anlagen and growth plate analyses during limb development at mouse embryonic days E 11.5, 13.5 and 17.5 showed dynamic changes in 5hmC levels in the differentiating chondrocytes. A similar increase in 5hmC levels was observed in the ATDC5 chondroprogenitor cell line accompanied by increased expression of the TET proteins during in vitro differentiation. Loss of TET1 in ATDC5 decreased 5hmC levels and impaired differentiation, demonstrating a functional role for TET1-mediated 5hmC dynamics in chondrogenic differentiation. Global analyses of the 5hmC-enriched sequences during early and late chondrogenic differentiation identified 5hmC distribution to be enriched in the regulatory regions of genes preceding the transcription start site (TSS) as well as in the gene bodies. Stable gains in 5hmC were observed in specific subsets of genes including genes associated with cartilage development and in chondrogenic lineage-specific genes. 5hmC gains in regulatory promoter and enhancer regions as well as in gene bodies were strongly associated with activated but not repressed genes, indicating a potential regulatory role for DNA hydroxymethylation in chondrogenic gene expression.