PARP1 Poly(ADP-ribosyl)ates Sox2 to Control Sox2 Protein Levels and FGF4 Expression during Embryonic Stem Cell Differentiation
PARP1 Poly(ADP-ribosyl)ates Sox2 to Control Sox2 Protein Levels and FGF4 Expression during Embryonic Stem Cell Differentiation
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PARP1 聚（ADP-核糖基）酯 Sox2 控制胚胎干细胞分化过程中的 Sox2 蛋白水平和 FGF4 表达
DOI：
10.1074/jbc.m109.033118
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发表时间：
2009-08-14
影响因子：
4.8
通讯作者：
Jin, Ying
中科院分区：
文献类型：
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作者：
Gao, Furong;Kwon, Sung Won;Jin, Ying
转录因子Oct4和Sox2是维持胚胎干细胞(ESCs)多能状态的关键因子。它们水平的微小变化会扰乱其目标基因的正常表达。然而，在ESCs中，Oct4和Sox2的蛋白水平及其靶基因的表达如何被精确控制仍然是个谜。在这里，我们发现PARP1是一种DNA结合蛋白，具有NAD(+)依赖的酶活性，是Oct4和Sox2的辅因子，调节其靶基因FGF4的表达。我们首次证明了PARP1与FGF4增强子结合以正向调节FGF4的表达。我们的数据表明，PARP1直接与Sox2相互作用并聚合(ADP-核糖基)SOX2，这可能是从FGF4增强子中解离和降解抑制Sox2蛋白所必需的步骤。当PARP1活性被抑制或缺失时，Sox2的聚合(ADP-核糖基)减少，Sox2与FGF4增强子的结合增加，伴随着Sox2蛋白水平的升高和FGF4的表达减少。值得注意的是，通过RNA干扰特异性地下调Sox2的表达可以显著地消除聚(ADPribose)聚合酶抑制剂对FGF4表达的抑制作用。有趣的是，PARP1缺乏并不影响未分化的ESCs，但当ESCs被诱导分化时，会影响细胞的存活和/或生长。在ESC分化过程中，加入FGF4可以部分挽救PARP1缺乏所引起的表型。综上所述，本研究揭示了在胚胎干细胞分化过程中Sox2蛋白水平和FGF4表达受到动态调节的新机制，并为调节ESCs特性的蛋白质家族增加了一个新的成员。
Transcription factors Oct4 and Sox2 are key players in maintaining the pluripotent state of embryonic stem cells (ESCs). Small changes in their levels disrupt normal expression of their target genes. However, it remains elusive how protein levels of Oct4 and Sox2 and expression of their target genes are precisely controlled in ESCs. Here we identify PARP1, a DNA-binding protein with an NAD(+)-dependent enzymatic activity, as a cofactor of Oct4 and Sox2 to regulate expression of their target gene FGF4. We demonstrate for the first time that PARP1 binds the FGF4 enhancer to positively regulate FGF4 expression. Our data show that PARP1 interacts with and poly(ADP-ribosyl)ates Sox2 directly, which may be a step required for dissociation and degradation of inhibitory Sox2 proteins from the FGF4 enhancer. When PARP1 activity is inhibited or absent, poly(ADP-ribosyl)ation of Sox2 decreases and association of Sox2 with FGF4 enhancers increases, accompanied by an elevated level of Sox2 proteins and reduced expression of FGF4. Significantly, specific knockdown of Sox2 expression by RNA interference can considerably abrogate the inhibitory effect of the poly(ADPribose) polymerase inhibitor on FGF4 expression. Interestingly, PARP1 deficiency does not affect undifferentiated ESCs but compromises cell survival and/or growth when ESCs are induced into differentiation. Addition of FGF4 can partially rescue the phenotypes caused by PARP1 deficiency during ESC differentiation. Taken together, this study uncovers new mechanisms through which Sox2 protein levels and FGF4 expression are dynamically regulated during ESC differentiation and adds a new member to the family of proteins regulating the properties of ESCs.