A tight control of Rif1 by Oct4 and Smad3 is critical for mouse embryonic stem cell stability
A tight control of Rif1 by Oct4 and Smad3 is critical for mouse embryonic stem cell stability
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Oct4 和 Smad3 对 Rif1 的严格控制对于小鼠胚胎干细胞的稳定性至关重要。
DOI：
10.1038/cddis.2014.551
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发表时间：
2015-01-01
影响因子：
9
通讯作者：
Yuan, P.
中科院分区：
文献类型：
--
作者：
Li, P.;Ma, X.;Yuan, P.
胚胎干细胞（ESCs）的长期培养导致它们具有胚胎癌细胞的特征，为它们的进一步应用创造了巨大的危险。然而，涉及ESC稳定性的机制尚未得到广泛研究。我们以前报道过SMAD家族成员3（Smad 3）在维持小鼠ESC稳定性方面具有重要作用，因为Smad 3的缺失导致ESC中的癌细胞样性质，并且Smad 3-/-ESC易于生长大的恶性畸胎瘤。为了了解Smad 3如何促进ESC稳定性，我们进行了微阵列分析以比较野生型和Smad 3-/-ESC的转录组。我们发现，Rif 1（RAP 1相关蛋白1），基因组稳定性的重要因素，是在Smad 3-/- ESCs显着上调。Rif 1的表达水平需要在ESC中严格控制，因为低水平的Rif 1与ESC分化相关，但高水平的Rif 1与ESC转化相关。在ESCs中，Oct 4激活Rif 1，而Smad 3抑制其表达。Oct 4募集Smad 3与Rif 1启动子结合，但Smad 3的结合有助于加载多梳复合物，该复合物在Rif 1启动子上产生抑制性表观遗传修饰，从而使Rif 1在ESCs中的表达保持在适当的水平。有趣的是，Rif 1短发夹RNA（shRNA）转导的Smad 3-/- ESCs显示出比对照shRNA转导的Smad 3-/- ESCs更少的恶性特性，这表明Rif 1在维持ESCs增殖过程中的稳定性方面起着关键作用。
Prolonged culture of embryonic stem cells (ESCs) leads them to adopt embryonal carcinoma cell features, creating enormous dangers for their further application. The mechanism involved in ESC stability has not, however, been extensively studied. We previously reported that SMAD family member 3 (Smad3) has an important role in maintaining mouse ESC stability, as depletion of Smad3 results in cancer cell-like properties in ESCs and Smad3-/- ESCs are prone to grow large, malignant teratomas. To understand how Smad3 contributes to ESC stability, we performed microarray analysis to compare the transcriptome of wild-type and Smad3-/- ESCs. We found that Rif1 (RAP1-associated protein 1), a factor important for genomic stability, is significantly upregulated in Smad3-/- ESCs. The expression level of Rif1 needs to be tightly controlled in ESCs, as a low level of Rif1 is associated with ESC differentiation, but a high level of Rif1 is linked to ESC transformation. In ESCs, Oct4 activates Rif1, whereas Smad3 represses its expression. Oct4 recruits Smad3 to bind to Rif1 promoter, but Smad3 joining facilitates the loading of a polycomb complex that generates a repressive epigenetic modification on Rif1 promoter, and thus maintains the expression of Rif1 at a proper level in ESCs. Interestingly, Rif1 short hairpin RNA (shRNA)-transduced Smad3-/- ESCs showed less malignant properties than the control shRNA-transduced Smad3-/- ESCs, suggesting a critical role of Rif1 in maintaining the stability of ESCs during proliferation.