Histone signature of metanephric mesenchyme cell lines
Histone signature of metanephric mesenchyme cell lines
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DOI：
10.4161/epi.25753
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发表时间：
2013-09-01
期刊：
影响因子：
3.7
通讯作者：
El-Dahr, Samir S.
中科院分区：
文献类型：
--
作者：
McLaughlin, Nathan;Yao, Xiao;El-Dahr, Samir S.
后肾间质（MM）产生肾元，肾元是成熟肾脏的过滤单位。MM由未诱导（Six2（高）/Lhx1（低））和诱导（wnt刺激，Six2（低）/Lhx1（高））细胞组成。MM细胞的整体表观遗传状态是未知的，部分原因是由于分离足够数量的同质细胞群的技术困难。因此，我们利用了两个小鼠克隆细胞系，分别代表未诱导的（mK3）和诱导的（mK4）后肾间质（基于基因表达谱和诱导输尿管芽分支的能力）。ChIP-Seq显示，H3K4me3活性区峰富集于代谢基因，而H3K27me3活性区峰修饰间质和上皮细胞命运承诺基因。在未诱导的mK3细胞中，茎秆基因启动子（如Six2、Osr1）富含H3K4me3峰；这些在诱导的mK4细胞中丢失。ChIP-qPCR证实了这一发现，并进一步证明G9a/H3K9me2在诱导细胞中占据Six2的启动子区域，符合转录的非活性状态。相反，标记诱导上皮化状态的基因（例如Lhx1， Pax8）分别在mK3和mK4细胞中从非允许的染色质特征转变为活跃的染色质特征。重要的是，在未诱导的mK3细胞中，刺激Wnt信号会引起染色质活性状态（高H3K4me3，低H3K27me3），沉默诱导基因中-catenin的募集和前结合组蛋白甲基转移酶Ezh2的缺失，随后转录激活。我们得出结论，未诱导和诱导细胞的染色质特征与其基因表达状态密切相关，表明染色质机制在MM细胞命运中起着重要作用。
The metanephric mesenchyme (MM) gives rise to nephrons, the filtering units of the mature kidney. The MM is composed of uninduced (Six2(high)/Lhx1(low)) and induced (Wnt-stimulated, Six2(low)/Lhx1(high)) cells. The global epigenetic state of MM cells is unknown, partly due to technical difficulty in isolating sufficient numbers of homogenous cell populations. We therefore took advantage of two mouse clonal cell lines representing the uninduced (mK3) and induced (mK4) metanephric mesenchyme (based on gene expression profiles and ability to induce branching of ureteric bud). ChIP-Seq revealed that whereas H3K4me3 active region peaks are enriched in metabolic genes, H3K27me3 peaks decorate mesenchyme and epithelial cell fate commitment genes. In uninduced mK3 cells, promoters of stemness genes (e.g., Six2, Osr1) are enriched with H3K4me3 peaks; these are lost in induced mK4 cells. ChIP-qPCR confirmed this finding and further demonstrated that G9a/H3K9me2 occupy the promoter region of Six2 in induced cells, consistent with the inactive state of transcription. Conversely, genes that mark the induced epithelialized state (e.g., Lhx1, Pax8), transition from a non-permissive to an active chromatin signature in mK3 vs. mK4 cells, respectively. Importantly, stimulation of Wnt signaling in uninduced mK3 cells provokes an active chromatin state (high H3K4me3, low H3K27me3), recruitment of -catenin, and loss of pre-bound histone methyltransferase Ezh2 in silent induced genes followed by activation of transcription. We conclude that the chromatin signature of uninduced and induced cells correlates strongly with their gene expression states, suggesting a role of chromatin-based mechanisms in MM cell fate.