Wang Hong, Gilner Jennifer B, Bautch Victoria L, Wang Da-Zhi, Wainwright Brandon J, Kirby Suzanne L, Patterson Cam
Carolina Cardiovascular Biology Center and Department of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
J Biol Chem. 2007 Jan 5;282(1):782-91. doi: 10.1074/jbc.M606610200. Epub 2006 Nov 10.
Our recent gene expression profiling analyses demonstrated that Wnt2 is highly expressed in Flk1(+) cells, which serve as common progenitors of endothelial cells, blood cells, and mural cells. In this report, we characterize the role of Wnt2 in mesoderm development during embryonic stem (ES) cell differentiation by creating ES cell lines in which Wnt2 was deleted. Wnt2(-/-) embryoid bodies (EBs) generated increased numbers of Flk1(+) cells and blast colony-forming cells compared with wild-type EBs, and had higher Flk1 expression at comparable stages of differentiation. Although Flk1(+) cells were increased, we found that endothelial cell and terminal cardiomyocyte differentiation was impaired, but hematopoietic cell differentiation was enhanced and smooth muscle cell differentiation was unchanged in Wnt2(-/-) EBs. Later stage Wnt2(-/-) EBs had either lower or undetectable expression of endothelial and cardiac genes compared with wild-type EBs. Consistently, vascular plexi were poorly formed and neither beating cardiomyocytes nor alpha-actinin-staining cells were detectable in later stage Wnt2(-/-) EBs. In contrast, hematopoietic cell gene expression was upregulated, and the number of hematopoietic progenitor colonies was significantly enhanced in Wnt2(-/-) EBs. Our data indicate that Wnt2 functions at multiple stages of development during ES cell differentiation and during the commitment and diversification of mesoderm: as a negative regulator for hemangioblast differentiation and hematopoiesis but alternatively as a positive regulator for endothelial and terminal cardiomyocyte differentiation.
我们最近的基因表达谱分析表明，Wnt2在Flk1(+)细胞中高表达，而Flk1(+)细胞是内皮细胞、血细胞和壁细胞的共同祖细胞。在本报告中，我们通过创建缺失Wnt2的胚胎干细胞（ES）系，来描述Wnt2在胚胎干细胞分化过程中中胚层发育中的作用。与野生型胚状体（EBs）相比，Wnt2(-/-)胚状体产生的Flk1(+)细胞和胚泡集落形成细胞数量增加，并且在分化的可比阶段具有更高的Flk1表达。虽然Flk1(+)细胞数量增加，但我们发现Wnt2(-/-)胚状体中内皮细胞和终末心肌细胞的分化受损，而造血细胞分化增强，平滑肌细胞分化未改变。与野生型胚状体相比，后期的Wnt2(-/-)胚状体中内皮和心脏基因的表达较低或无法检测到。一致地，Wnt2(-/-)胚状体后期血管丛形成不良，未检测到跳动的心肌细胞和α-肌动蛋白染色细胞。相反，Wnt2(-/-)胚状体中造血细胞基因表达上调，造血祖细胞集落数量显著增加。我们的数据表明，Wnt2在胚胎干细胞分化以及中胚层的定向和多样化过程中的多个发育阶段发挥作用：作为成血管细胞分化和造血的负调节因子，但作为内皮细胞和终末心肌细胞分化的正调节因子。
