The stepwise specification of embryonic stem cells to hematopoietic fate is driven by sequential exposure to Bmp4, activin A, bFGF and VEGF
The stepwise specification of embryonic stem cells to hematopoietic fate is driven by sequential exposure to Bmp4, activin A, bFGF and VEGF
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DOI：
10.1242/dev.011767
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发表时间：
2008-04-15
期刊：
影响因子：
4.6
通讯作者：
Kouskoff, Valerie
中科院分区：
文献类型：
--
作者：
Pearson, Stella;Sroczynska, Patrycja;Kouskoff, Valerie
胚胎干细胞的分化为研究细胞命运决定机制提供了有力的途径。然而，一个主要的障碍是促进ES细胞向特定谱系定向高效分化。在这里，我们定义了在无血清培养中控制分化过程每一步的最低因素需求，从而产生高度浓缩的造血祖细胞。四种因子--Bmp4、激活素A、碱性成纤维细胞生长因子(FGF2)和血管内皮生长因子(VEGFA)--足以驱动小鼠ES细胞选择性高效地向造血细胞分化。这些因素中的每一个似乎都调控着这一过程的一个步骤：BMP4促进非常有效的中胚层形成；碱性成纤维细胞生长因子和激活素A诱导这些中胚层前体向血管母细胞的命运分化；而血管内皮生长因子是产生完全承诺的造血祖细胞所必需的。碱性成纤维细胞生长因子和激活素A对中胚层前体的刺激非常迅速地启动了造血程序，使我们能够剖析导致血管母细胞形成的分子事件。RUNX1、scl(Tal1)和HHEX在刺激3h内表达上调，而Lmo2和FlI1在刺激后表达上调。有趣的是，cMyb、Pu等基因的表达水平增加。1(Sfpi1)、GATA1和GATA2在血管母细胞着床开始时没有观察到。这种对分化的循序渐进的控制是非常有效的，产生了非常高的造血祖细胞频率，并为理解涉及血祖细胞承诺的分子机制提供了一个最佳系统。
The differentiation of embryonic stem (ES) cells offers a powerful approach to study mechanisms implicated in cell fate decision. A major hurdle, however, is to promote the directed and efficient differentiation of ES cells toward a specific lineage. Here, we define in serum-free media the minimal factor requirement controlling each step of the differentiation process, resulting in the production of highly enriched hematopoietic progenitors. Four factors-Bmp4, activin A, bFGF (Fgf2) and VEGF (VegfA)-are sufficient to drive the selective and efficient differentiation of mouse ES cells to hematopoiesis. Each of these factors appears to regulate a step of the process: Bmp4 promotes the very efficient formation of mesoderm; bFGF and activin A induce the differentiation of these mesodermal precursors to the hemangioblast fate; and VEGF is required for the production of fully committed hematopoietic progenitors. The stimulation of mesodermal precursors by bFGF and activin A switches on very rapidly the hematopoietic program, allowing us to dissect the molecular events leading to the formation of the hemangioblast. Runx1, Scl (Tal1) and Hhex expression is upregulated within 3 hours of stimulation, whereas upregulation of Lmo2 and Fli1 is observed later. Interestingly, increased expression levels of genes such as cMyb, Pu. 1 (Sfpi1), Gata1 and Gata2 are not observed at the onset of hemangioblast commitment. This stepwise control of differentiation is extremely efficient, giving rise to a very high frequency of hematopoietic precursors, and provides an optimal system for understanding the molecular machineries involved in blood progenitor commitment.