Comparative analyses of SUV420H1 isoforms and SUV420H2 reveal differences in their cellular localization and effects on myogenic differentiation.
Comparative analyses of SUV420H1 isoforms and SUV420H2 reveal differences in their cellular localization and effects on myogenic differentiation.
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DOI：
10.1371/journal.pone.0014447
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发表时间：
2010-12-29
期刊：
影响因子：
3.7
通讯作者：
Underhill DA
中科院分区：
文献类型：
--
作者：
Tsang LW;Hu N;Underhill DA
组蛋白 H4 在赖氨酸 20 上的甲基化通过单 (H4K20me1)、二 (H4K20me2) 和三甲基 (H4K20me3) 衍生物在染色质结构和功能中发挥关键作用。在之前对妊娠中期小鼠胚胎组蛋白甲基化动态的分析中，我们记录了细胞分化过程中 H4K20 甲基化的显着变化。这些变化在体内和细胞培养中的肌生成过程中尤其明显，我们观察到从 H4K20me1 到 H4K20me3 的转变。为了评估这一变化的重要性，我们使用了涉及赖氨酸甲基转移酶 SUV420H1 和 SUV420H2 的功能获得策略，它们催化 H4K20me2 和 H4K20me3。与此同时，我们对 SUV420H1 的第二种亚型（称为 SUV420H1_i2）进行了表征，并比较了所有三种 SUV420H 蛋白在定位和 H4K20 甲基化方面的活性。免疫荧光显示外源SUV420H1_i2分布在整个细胞中，而SUV420H1_i1和SUV420H2的大部分显示出与组成型异染色质的预期关联。此外，SUV420H1_i2的分布不受异染色质蛋白1α共表达的影响，这增加了SUV420H1_i1和SUV420H2对着丝粒周围异染色质区域的靶向性。与它们的分布一致，SUV420H1_i2导致整个细胞核中H4K20me3水平的增加，而SUV420H1_i1和SUV420H2促进了中心周H4K20me3的增加。当 SUV420H 蛋白在 C2C12 生肌模型系统中进行测试时，显着的差异仍在继续。具体而言，尽管SUV420H1_i2在有丝分裂原存在的情况下诱导分化标记物肌细胞生成素的过早出现，但只有SUV420H2在分化过程中维持了肌细胞生成素富集的群体。矛盾的是，SUV420H1_i1 不能在 C2C12 细胞中表达，这表明它处于转录后或翻译后控制之下。这些数据表明 SUV420H 蛋白的定位和活性存在显着差异。重要的是，SUV420H2 可以在组成型异染色质区域诱导从 H4K20me1 到 H4K20me3 的转变，这足以增强肌原性分化，表明它可以在此过程中充当表观遗传“开关”。
Methylation of histone H4 on lysine 20 plays critical roles in chromatin structure and function via mono- (H4K20me1), di- (H4K20me2), and trimethyl (H4K20me3) derivatives. In previous analyses of histone methylation dynamics in mid-gestation mouse embryos, we documented marked changes in H4K20 methylation during cell differentiation. These changes were particularly robust during myogenesis, both in vivo and in cell culture, where we observed a transition from H4K20me1 to H4K20me3. To assess the significance of this change, we used a gain-of-function strategy involving the lysine methyltransferases SUV420H1 and SUV420H2, which catalyze H4K20me2 and H4K20me3. At the same time, we characterized a second isoform of SUV420H1 (designated SUV420H1_i2) and compared the activity of all three SUV420H proteins with regard to localization and H4K20 methylation. Immunofluorescence revealed that exogenous SUV420H1_i2 was distributed throughout the cell, while a substantial portion of SUV420H1_i1 and SUV420H2 displayed the expected association with constitutive heterochromatin. Moreover, SUV420H1_i2 distribution was unaffected by co-expression of heterochromatin protein-1α, which increased the targeting of SUV420H1_i1 and SUV420H2 to regions of pericentromeric heterochromatin. Consistent with their distributions, SUV420H1_i2 caused an increase in H4K20me3 levels throughout the nucleus, whereas SUV420H1_i1 and SUV420H2 facilitated an increase in pericentric H4K20me3. Striking differences continued when the SUV420H proteins were tested in the C2C12 myogenic model system. Specifically, although SUV420H1_i2 induced precocious appearance of the differentiation marker Myogenin in the presence of mitogens, only SUV420H2 maintained a Myogenin-enriched population over the course of differentiation. Paradoxically, SUV420H1_i1 could not be expressed in C2C12 cells, which suggests it is under post-transcriptional or post-translational control. These data indicate that SUV420H proteins differ substantially in their localization and activity. Importantly, SUV420H2 can induce a transition from H4K20me1 to H4K20me3 in regions of constitutive heterochromatin that is sufficient to enhance myogenic differentiation, suggesting it can act an as epigenetic ‘switch’ in this process.
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影响因子：
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作者：
Margueron, Raphael;Li, Guohong;Sarma, Kavitha;Blais, Alexandre;Zavadil, Jiri;Woodcock, Christopher L.;Dyniacht, Brian D.;Reinberg, Danny
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