MAPK1 mediates C/EBPβ phosphorylation to promote maturation and inhibit EMT process in hESC-derived hepatocytes [RNA-seq]

Human pluripotent stem cell (hPSC)-derived hepatocytes exhibit progressive differentiation toward a phenotype resembling primary human hepatocytes (PHHs). Nevertheless, they still display persistent functional deficiencies in key mature hepatocyte properties, particularly in albumin secretion and ammonia metabolism, remain challenge compared to PHHs. In this study, we elucidated a critical regulatory role of CCAAT/enhancer-binding protein beta (C/EBPβ) in hepatocyte maturation. Forced expression of C/EBPβ significantly enhanced hepatic functionality, as evidenced by increased albumin secretion, upregulation of hepatic-specific genes, and suppression of epithelial-mesenchymal transition (EMT) markers. Mechanistically, we found that C/EBPβ directly binded to the promoter regions of E-cadherin (E-cad) and carbamoyl phosphate synthetase 1 (CPS1), enhancing their transcriptional activation. Furthermore, we identified a functional interaction between C/EBPβ and MAPK signaling, where MAPK1-mediated phosphorylation at Thr-235 potentiated C/EBPβ's transactivation capacity, thereby promoting hepatocyte differentiation and maturation. Our findings establish C/EBPβ as a master regulator of hepatic maturation, orchestrating transcriptional networks and post-translational modification. These insights provide a theoretical framework for optimizing stem cell-derived hepatocyte differentiation, facilitating their applications in various fields.