Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad Complutense de Madrid; 28040 Madrid, Spain.
Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), 28040 Madrid, Spain.
Int J Biol Sci. 2022 Sep 25;18(15):5873-5884. doi: 10.7150/ijbs.73192. eCollection 2022.
Previous data indicate that C3G (RapGEF1) main isoform is highly expressed in liver progenitor cells (or oval cells) compared to adult mature hepatocytes, suggesting it may play an important role in oval cell biology. Hence, we have explored C3G function in the regulation of oval cell properties by permanent gene silencing using shRNAs. We found that C3G knock-down enhanced migratory and invasive ability of oval cells by promoting a partial epithelial to mesenchymal transition (EMT). This is likely mediated by upregulation of mRNA expression of the EMT-inducing transcription factors, , and , induced in C3G-silenced oval cells. This EMT is associated to a higher expression of the stemness markers, CD133 and CD44. Moreover, C3G down-regulation increased oval cells clonogenic capacity by enhancing cell scattering. However, C3G knock-down did not impair oval cell differentiation into hepatocyte lineage. Mechanistic studies revealed that HGF/MET signaling and its pro-invasive activity was impaired in oval cells with low levels of C3G, while TGF-β signaling was increased. Altogether, these data suggest that C3G might be tightly regulated to ensure liver repair in chronic liver diseases such as non-alcoholic steatohepatitis. Hence, reduced C3G levels could facilitate oval cell expansion, after the proliferation peak, by enhancing migration.
先前的数据表明，与成年成熟肝细胞相比，C3G（RapGEF1）的主要同工型在肝祖细胞（或卵圆细胞）中高度表达，这表明它可能在卵圆细胞生物学中发挥重要作用。因此，我们通过使用 shRNA 进行永久基因沉默来探索 C3G 在调节卵圆细胞特性方面的功能。我们发现，C3G 敲低通过促进部分上皮间质转化（EMT）来增强卵圆细胞的迁移和侵袭能力。这可能是通过 C3G 沉默的卵圆细胞中 EMT 诱导转录因子、、和的 mRNA 表达上调介导的。这种 EMT 与干细胞标志物 CD133 和 CD44 的高表达相关。此外，C3G 下调通过增强细胞散射增加了卵圆细胞的集落形成能力。然而，C3G 敲低并没有损害卵圆细胞向肝谱系的分化。机制研究表明，在 C3G 水平较低的卵圆细胞中，HGF/MET 信号及其促侵袭活性受损，而 TGF-β 信号增强。总的来说，这些数据表明，C3G 可能受到严格调控，以确保慢性肝病（如非酒精性脂肪性肝炎）中的肝脏修复。因此，C3G 水平降低可能会通过增强迁移来促进增殖高峰期后卵圆细胞的扩张。
