Tarafdar Anuradha, Dobbin Edwina, Corrigan Pamela, Freeburn Robin, Wheadon Helen
Paul O'Gorman Leukaemia Research Centre, University of Glasgow, United Kingdom ; Biomedical Science Institute, University of Ulster, Northern Ireland, United Kingdom.
PLoS One. 2013 Nov 26;8(11):e81030. doi: 10.1371/journal.pone.0081030. eCollection 2013.
The generation of hematopoietic stem cells (HSCs) during development is a complex process linked to morphogenic signals. Understanding this process is important for regenerative medicine applications that require in vitro production of HSC. In this study we investigated the effects of canonical Wnt/β-catenin signaling during early embryonic differentiation and hematopoietic specification using an embryonic stem cell system. Our data clearly demonstrates that following early differentiation induction, canonical Wnt signaling induces a strong mesodermal program whilst maintaining a degree of stemness potential. This involved a complex interplay between β-catenin/TCF/LEF/Brachyury/Nanog. β-catenin mediated up-regulation of TCF/LEF resulted in enhanced brachyury levels, which in-turn lead to Nanog up-regulation. During differentiation, active canonical Wnt signaling also up-regulated key transcription factors and cell specific markers essential for hematopoietic specification, in particular genes involved in establishing primitive erythropoiesis. This led to a significant increase in primitive erythroid colony formation. β-catenin signaling also augmented early hematopoietic and multipotent progenitor (MPP) formation. Following culture in a MPP specific cytokine cocktail, activation of β-catenin suppressed differentiation of the early hematopoietic progenitor population, with cells displaying a higher replating capacity and a propensity to form megakaryocytic erythroid progenitors. This bias towards erythroid lineage commitment was also observed when hematopoietic progenitors were directed to undergo myeloid colony formation. Overall this study underscores the importance of canonical Wnt/β-catenin signaling in mesodermal specification, primitive erythropoiesis and early hematopietic progenitor formation during hematopoietic induction.
发育过程中造血干细胞（HSCs）的产生是一个与形态发生信号相关的复杂过程。了解这一过程对于需要在体外生产造血干细胞的再生医学应用至关重要。在本研究中，我们使用胚胎干细胞系统研究了经典Wnt/β-连环蛋白信号在早期胚胎分化和造血特化过程中的作用。我们的数据清楚地表明，在早期分化诱导后，经典Wnt信号诱导了强大的中胚层程序，同时保持了一定程度的干性潜能。这涉及β-连环蛋白/TCF/LEF/短尾型/ Nanog之间的复杂相互作用。β-连环蛋白介导的TCF/LEF上调导致短尾型水平升高，进而导致Nanog上调。在分化过程中，活跃的经典Wnt信号还上调了造血特化所必需的关键转录因子和细胞特异性标志物，特别是参与建立原始红细胞生成的基因。这导致原始红细胞集落形成显著增加。β-连环蛋白信号也增强了早期造血和多能祖细胞（MPP）的形成。在MPP特异性细胞因子混合物中培养后，β-连环蛋白的激活抑制了早期造血祖细胞群体的分化，细胞表现出更高的再接种能力和形成巨核红细胞祖细胞的倾向。当造血祖细胞被引导进行髓系集落形成时，也观察到了这种向红细胞谱系定向的偏向。总体而言，本研究强调了经典Wnt/β-连环蛋白信号在造血诱导过程中的中胚层特化、原始红细胞生成和早期造血祖细胞形成中的重要性。
