The Wnt/β-catenin signaling pathway is a key regulator of embryonic stem cell (ESC) self-renewal and differentiation. Constitutive activation of this pathway has been shown to increase mouse ESC (mESC) self-renewal and pluripotency gene expression. In this study, we generated a novel β-catenin knockout model in mESCs to delete putatively functional N-terminally truncated isoforms observed in previous knockout models. We showed that aberrant N-terminally truncated isoforms are not functional in mESCs. In the generated knockout line, we observed that canonical Wnt signaling is not active, as β-catenin ablation does not alter mESC transcriptional profile in serum/LIF culture conditions. In addition, we observed that Wnt signaling activation represses mESC spontaneous differentiation in a β-catenin-dependent manner. Finally, β-catenin (ΔC) isoforms can rescue β-catenin knockout self-renewal defects in mESCs cultured in serum-free medium and, albeit transcriptionally silent, cooperate with TCF1 and LEF1 to inhibit mESC spontaneous differentiation in a GSK3-dependent manner.

Wnt /β-catenin信号通路是胚胎干细胞（ESC）自我更新和分化的关键调节因子。已经证明，该途径的组成性激活会增加小鼠ESC（mESC）的自我更新和多能性基因表达。在这项研究中，我们在mESC中生成了一个新型的β-catenin敲除模型，以删除先前敲除模型中观察到的推定的功能性N末端截短的亚型。我们表明异常的N末端截短的同工型在mESCs中不起作用。在产生的敲除品系中，我们观察到经典的Wnt信号不活跃，因为在血清/ LIF培养条件下，β-catenin消融不会改变mESC转录谱。此外，我们观察到Wnt信号激活以β-catenin依赖性方式抑制mESC自发分化。最后，