Tang Dan, Chen Yi, Fu Gong-Bo, Yuan Tian-Jie, Huang Wei-Jian, Wang Zhen-Yu, Li Wei-Jian, Jiao Ying-Fu, Yu Wei-Feng, Yan He-Xin
Department of Anesthesiology and Critical Care Medicine, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.
International Cooperation Laboratory on Signal Transduction, Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai, China.
Biochem Biophys Res Commun. 2020 Feb 19. doi: 10.1016/j.bbrc.2020.02.041.
In both normal turnover of the hepatic tissue and acute hepatic injury, the liver predominantly activates terminally differentiated hepatocytes to proliferate and repair. However, in chronic and severe chronic injury, this capacity fails, and liver progenitor cells (LPCs) can give rise to hepatocytes to restore both hepatic architecture and liver metabolic function. Although the promotion of LPC-to-hepatocyte differentiation to acquire a considerable number of functional hepatocytes could serve as a potentially new therapeutic option for patients with end-stage liver disease, its development first requires the identification of the molecular mechanisms driving this process. Here, we found that the epithelial cell adhesion molecule (EpCAM), a progenitor cell marker, regulates the differentiation of LPCs into hepatocytes through Notch1 signaling pathway. Western blotting (WB) revealed a consistent expression pattern of EpCAM and Notch1 during LPC-to-hepatocyte differentiation in vitro. Additionally, overexpression of EpCAM blocked LPC-to-hepatocyte differentiation, which was in consistent with the repressive role of Notch signaling during hepatic differentiation. WB and immunofluorescence data also showed that the upregulation of EpCAM expression increased the generation of Notch intracellular domain (NICD), indicating the promotion of Notch1 activity. Our results established the EpCAM-Notch1 signaling axis as an inhibitory mechanism preventing LPC-to-hepatocyte differentiation in vitro.
在肝组织的正常更新和急性肝损伤过程中，肝脏主要激活终末分化的肝细胞进行增殖和修复。然而，在慢性和严重慢性损伤中，这种能力失效，肝祖细胞（LPCs）可产生肝细胞以恢复肝脏结构和肝脏代谢功能。尽管促进LPC向肝细胞分化以获得大量功能性肝细胞可作为终末期肝病患者潜在的新治疗选择，但其发展首先需要确定驱动这一过程的分子机制。在此，我们发现上皮细胞粘附分子（EpCAM），一种祖细胞标志物，通过Notch1信号通路调节LPC向肝细胞的分化。蛋白质印迹法（WB）显示在体外LPC向肝细胞分化过程中EpCAM和Notch1具有一致的表达模式。此外，EpCAM的过表达阻断了LPC向肝细胞的分化，这与Notch信号在肝脏分化过程中的抑制作用一致。WB和免疫荧光数据还表明，EpCAM表达上调增加了Notch细胞内结构域（NICD）的产生，表明Notch1活性增强。我们的结果确立了EpCAM-Notch1信号轴作为体外阻止LPC向肝细胞分化的一种抑制机制。
