The role of WDR5 in silencing human fetal globin gene expression
The role of WDR5 in silencing human fetal globin gene expression
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DOI：
10.3324/haematol.2012.061937
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发表时间：
2012-11
期刊：
影响因子：
10.1
通讯作者：
Zhen Xu;Yinghong He;Junyi Ju;Gerhard Rank;L. Cerruti;Chi Ma;R. Simpson;R. Moritz;S. Jane;Quan Zhao
中科院分区：
文献类型：
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作者：
Zhen Xu;Yinghong He;Junyi Ju;Gerhard Rank;L. Cerruti;Chi Ma;R. Simpson;R. Moritz;S. Jane;Quan Zhao
在哺乳动物细胞中，组蛋白H3赖氨酸4 （K4）甲基化与转录活性有关。WD40-repeat蛋白WDR5是MLL复合物中诱导组蛋白H3 K4甲基化的重要组成部分，但WDR5在人类珠蛋白基因调控中的作用尚未确定。为了研究WDR5在人珠蛋白基因调控中的作用，我们在K562细胞和原代人骨髓红细胞祖细胞（BMC）中进行了敲低实验。观察WDR5基因敲低对γ-珠蛋白基因表达的影响。生化方法也被用于研究WDR5相互作用分子。用ChIP分析珠蛋白位点的染色体标记。结果我们发现WDR5与蛋白精氨酸甲基转移酶5 （PRMT5）相互作用，PRMT5是一种已知的γ-珠蛋白基因表达抑制因子，在K562细胞中γ-珠蛋白启动子上产生三甲基化的H3K4 （H3K4me3）所必需的。在K562细胞中，WDR5的强表达降低了γ-珠蛋白基因的表达，而在K562细胞和原代人骨髓红系祖细胞中，WDR5的低表达均增加了γ-珠蛋白基因的表达。与此一致的是，与对照组相比，在WDR5敲除的细胞中，γ-珠蛋白启动子上的组蛋白H3和H4乙酰化增加，而组蛋白H4R3和H3K9甲基化减少。我们发现WDR5与HDAC1和含有PHD结构域的蛋白ING2（生长抑制剂）（H3K4me3标记读取器）相互作用，增强γ-珠蛋白基因的转录抑制。在人BMC中，相对于其他珠蛋白启动子和脐血红细胞祖细胞中的γ-启动子，WDR5的水平在γ-启动子上高度富集，表明WDR5在发育性珠蛋白基因表达程序中起重要作用。结论我们的数据与WDR5以依赖prmt5的方式结合γ-珠蛋白启动子的模型一致；WDR5在γ-珠蛋白启动子处诱导的H3K4me3可能导致ing2相关HDAC1成分的募集，从而导致γ-珠蛋白基因表达的沉默。
Background Histone H3 lysine 4 (K4) methylation has been linked with transcriptional activity in mammalian cells. The WD40-repeat protein, WDR5, is an essential component of the MLL complex that induces histone H3 K4 methylation, but the role of WDR5 in human globin gene regulation has not yet been established. Design and Methods To study the role of WDR5 in human globin gene regulation, we performed knockdown experiments in both K562 cells and primary human bone marrow erythroid progenitor cells (BMC). The effects of WDR5 knockdown on γ-globin gene expression were determined. Biochemical approaches were also employed to investigate WDR5 interaction molecules. Chromosomal marks in the globin locus were analyzed by ChIP. Results We found that WDR5 interacted with protein arginine methyltransferase 5 (PRMT5), a known repressor of γ-globin gene expression, and was essential for generating tri-methylated H3K4 (H3K4me3) at the γ-globin promoter in K562 cells. Enforced expression of WDR5 in K562 cells reduced γ-globin gene expression, whereas knockdown of WDR5 increased γ-globin gene expression in both K562 cells and primary human bone marrow erythroid progenitor cells. Consistent with this, both histone H3 and H4 acetylation at the γ-globin promoter were increased, while histone H4R3 and H3K9 methylation were decreased, in WDR5 knockdown cells compared to controls. We found that WDR5 interacted with HDAC1 and a PHD domaincontaining protein, ING2 (inhibitor of growth), an H3K4me3 mark reader, to enhance γ-globin gene transcriptional repression. In human BMC, levels of WDR5 were highly enriched on the γ-promoter relative to levels on other globin promoters and compared to the γ-promoter in cord blood erythroid progenitors, suggesting that WDR5 is important in the developmental globin gene expression program. Conclusions Our data are consistent with a model in which WDR5 binds the γ-globin promoter in a PRMT5-dependent manner; H3K4me3 induced at the γ-globin promoter by WDR5 may result in the recruitment of the ING2-associated HDAC1 component and consequent silencing of γ-globin gene expression.