Porphyrin homeostasis maintained by ABCG2 regulates self-renewal of embryonic stem cells.
Porphyrin homeostasis maintained by ABCG2 regulates self-renewal of embryonic stem cells.
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ABCG2维持的卟啉稳态调节胚胎干细胞的自我更新。
DOI：
10.1371/journal.pone.0004023
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发表时间：
2008
期刊：
影响因子：
3.7
通讯作者：
Shen CN
中科院分区：
文献类型：
--
作者：
Susanto J;Lin YH;Chen YN;Shen CR;Yan YT;Tsai ST;Chen CH;Shen CN
在适当的培养条件下，未分化的胚胎干细胞（ES）可以经历多个自我更新周期而不丧失多能性，这表明它们必须配备特定的防御机制，以确保在自我更新扩增过程中具有足够的遗传稳定性。ATP结合盒转运蛋白ABCG 2在多种体细胞和胚胎干细胞中表达。然而，它是否在干细胞维持中发挥重要作用仍有待确定。在这里，我们提供的证据表明，ABCG 2的水平增加，观察伴随着ES集落扩张，然后由原卟啉IX（PPIX）的水平下降，表明ABCG 2起着维持卟啉稳态的作用。RNA干扰介导的ABCG 2抑制以及用烟曲霉素C（FTC）（一种特异性和有效的ABCG 2抑制剂）功能性阻断ABCG 2转运蛋白，不仅提高了PPIX的细胞水平，而且还阻止了细胞周期并降低了多能基因Nanog的表达。ABCG 2在ES细胞中的过表达能够抵消5-氨基乙酰丙酸诱导的内源性PPIX的增加，表明ABCG 2在从ES细胞去除PPIX中起直接作用。我们还发现，ES细胞中过量的PPIX导致活性氧水平升高，这反过来触发了DNA损伤信号，如γ H2 AX和磷酸化p53水平升高所示。p53水平的增加降低了Nanog表达，因为RNA干扰介导的p53抑制能够防止FTC处理诱导的Nanog下调。目前的工作表明，ABCG 2保护ES细胞在集落扩增过程中免受PPIX积累，并且p53和γ H2 AX作为ABCG 2依赖性防御机制的下游检查点以维持ES细胞的自我更新。
Under appropriate culture conditions, undifferentiated embryonic stem (ES) cells can undergo multiple self-renewal cycles without loss of pluripotency suggesting they must be equipped with specific defense mechanisms to ensure sufficient genetic stability during self-renewal expansion. The ATP binding cassette transporter ABCG2 is expressed in a wide variety of somatic and embryonic stem cells. However, whether it plays an important role in stem cell maintenance remains to be defined. Here we provide evidence to show that an increase in the level of ABCG2 was observed accompanied by ES colony expansion and then were followed by decreases in the level of protoporphyrin IX (PPIX) indicating that ABCG2 plays a role in maintaining porphyrin homoeostasis. RNA-interference mediated inhibition of ABCG2 as well as functional blockage of ABCG2 transporter with fumitremorgin C (FTC), a specific and potent inhibitor of ABCG2, not only elevated the cellular level of PPIX, but also arrest the cell cycle and reduced expression of the pluripotent gene Nanog. Overexpression of ABCG2 in ES cells was able to counteract the increase of endogenous PPIX induced by treatment with 5-Aminolevulinic acid suggesting ABCG2 played a direct role in removal of PPIX from ES cells. We also found that excess PPIX in ES cells led to elevated levels of reactive oxygen species which in turn triggered DNA damage signals as indicated by increased levels of γH2AX and phosphorylated p53. The increased level of p53 reduced Nanog expression because RNA- interference mediated inhibition of p53 was able to prevent the downregulation of Nanog induced by FTC treatment. The present work demonstrated that ABCG2 protects ES cells from PPIX accumulation during colony expansion, and that p53 and γH2AX acts as a downstream checkpoint of ABCG2-dependent defense machinery in order to maintain the self-renewal of ES cells.
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影响因子：
3.8
作者：
de Waard, H;de Wit, J;van der Horst, GTJ
通讯作者：
van der Horst, GTJ
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