Pistoni Mariaelena, Helsen Nicky, Vanhove Jolien, Boon Ruben, Xu Zhuofei, Ordovas Laura, Verfaillie Catherine M
KU Leuven-Department Development and Regeneration, Stem Cell Institute (SCIL), Leuven, Belgium.
PLoS One. 2017 Nov 1;12(11):e0186884. doi: 10.1371/journal.pone.0186884. eCollection 2017.
Currently, drug metabolization and toxicity studies rely on the use of primary human hepatocytes and hepatoma cell lines, which both have conceivable limitations. Human pluripotent stem cell (hPSC)-derived hepatocyte-like cells (HLCs) are an alternative and valuable source of hepatocytes that can overcome these limitations. EZH2 (enhancer of zeste homolog 2), a transcriptional repressor of the polycomb repressive complex 2 (PRC2), may play an important role in hepatocyte development, but its role during in vitro hPSC-HLC differentiation has not yet been assessed. We here demonstrate dynamic regulation of EZH2 during hepatic differentiation of hPSC. To enhance EZH2 expression, we inducibly overexpressed EZH2 between d0 and d8, demonstrating a significant improvement in definitive endoderm formation, and improved generation of HLCs. Despite induction of EZH2 overexpression until d8, EZH2 transcript and protein levels decreased from d4 onwards, which might be caused by expression of microRNAs predicted to inhibit EZH2 expression. In conclusion, our studies demonstrate that EZH2 plays a role in endoderm formation and hepatocyte differentiation, but its expression is tightly post-transcriptionally regulated during this process.
目前，药物代谢和毒性研究依赖于原代人肝细胞和肝癌细胞系的使用，而这两者都存在明显的局限性。人多能干细胞（hPSC）衍生的肝样细胞（HLC）是一种可替代的、有价值的肝细胞来源，能够克服这些局限性。EZH2（zeste同源物2增强子）是多梳抑制复合物2（PRC2）的转录抑制因子，可能在肝细胞发育中起重要作用，但尚未评估其在体外hPSC-HLC分化过程中的作用。我们在此证明了hPSC肝分化过程中EZH2的动态调控。为了增强EZH2表达，我们在第0天至第8天之间诱导性过表达EZH2，结果显示在确定内胚层形成方面有显著改善，并且HLC的生成也得到了改善。尽管EZH2过表达一直诱导到第8天，但从第4天起EZH2转录本和蛋白水平下降，这可能是由预测可抑制EZH2表达的微小RNA的表达所致。总之，我们的研究表明EZH2在内胚层形成和肝细胞分化中起作用，但在此过程中其表达受到严格的转录后调控。
