E-cadherin is required for the proper activation of the Lifr/Gp130 signaling pathway in mouse embryonic stem cells
E-cadherin is required for the proper activation of the Lifr/Gp130 signaling pathway in mouse embryonic stem cells
复制标题
DOI：
10.1242/dev.088690
复制
发表时间：
2013-04-15
期刊：
影响因子：
4.6
通讯作者：
Kemler, Rolf
中科院分区：
文献类型：
--
作者：
del Valle, Ignacio;Rudloff, Stefan;Kemler, Rolf
白血病抑制因子(Lif)信号通路是小鼠胚胎干细胞(MES)自我更新和多能性的关键决定因素。MES细胞的特征之一是其致密的生长形态，是通过E-钙粘蛋白、β-连环蛋白(CTNNB1)和α-连环蛋白与肌动蛋白细胞骨架介导的紧密细胞黏附的结果。β-连环蛋白也参与了典型的Wnt信号，这也被认为是控制MES细胞干细胞的一个因素。在这里，我们分析了由E-钙粘蛋白-α-连环蛋白(Eα)融合蛋白(CTNNB1(-/-)EαMES细胞)维持细胞黏附的CTNNB1(-/-)MES细胞，并表明仅模仿β-连环蛋白的黏附功能是维持MES细胞状态的必要条件和充分条件，使得β-连环蛋白/Wnt信号在这一过程中过时。此外，我们提出了E-钙粘蛋白在促进LIF信号级联中的作用，显示了E-钙粘蛋白与LIFR-gp130受体复合体的关联，这很可能是由E-钙粘蛋白的胞外结构域促进的。如果没有Eα，因此没有维持细胞黏附，CTNNB1(-/-)MES细胞下调Lif信号通路的组成部分，如LifR、gp130和激活的STAT3，以及多能性相关标记。根据这些观察，我们假设伴随着多能性丧失的基因表达的变化是细胞黏附功能障碍的直接结果。支持这一观点，我们发现，通过强制表达结构性活性的STAT3，可以绕过对完整粘连的要求。综上所述，我们提出了一个模型，在该模型中，MES细胞可以在没有CTNNB1的情况下在培养中增殖，只要保持E-钙粘附素介导的细胞黏附。
The leukemia inhibitory factor (Lif) signaling pathway is a crucial determinant for mouse embryonic stem (mES) cell self-renewal and pluripotency. One of the hallmarks of mES cells, their compact growth morphology, results from tight cell adhesion mediated through E-cadherin, beta-catenin (Ctnnb1) and alpha-catenin with the actin cytoskeleton. beta-catenin is also involved in canonical Wnt signaling, which has also been suggested to control mES cell stemness. Here, we analyze Ctnnb1(-/-) mES cells in which cell adhesion is preserved by an E-cadherin-alpha-catenin (E alpha) fusion protein (Ctnnb1(-/-)E alpha mES cells), and show that mimicking only the adhesive function of beta-catenin is necessary and sufficient to maintain the mES cell state, making beta-catenin/Wnt signaling obsolete in this process. Furthermore, we propose a role for E-cadherin in promoting the Lif signaling cascade, showing an association of E-cadherin with the Lifr-Gp130 receptor complex, which is most likely facilitated by the extracellular domain of E-cadherin. Without E alpha, and thus without maintained cell adhesion, Ctnnb1(-/-) mES cells downregulate components of the Lif signaling pathway, such as Lifr, Gp130 and activated Stat3, as well as pluripotency-associated markers. From these observations, we hypothesize that the changes in gene expression accompanying the loss of pluripotency are a direct consequence of dysfunctional cell adhesion. Supporting this view, we find that the requirement for intact adhesion can be circumvented by the forced expression of constitutively active Stat3. In summary, we put forward a model in which mES cells can be propagated in culture in the absence of Ctnnb1, as long as E-cadherin-mediated cell adhesion is preserved.