The Flk1-Cre-Mediated Deletion of ETV2 Defines Its Narrow Temporal Requirement During Embryonic Hematopoietic Development
The Flk1-Cre-Mediated Deletion of ETV2 Defines Its Narrow Temporal Requirement During Embryonic Hematopoietic Development
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DOI：
10.1002/stem.1115
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发表时间：
2012-07-01
期刊：
影响因子：
5.2
通讯作者：
Kouskoff, Valerie
中科院分区：
文献类型：
--
作者：
Wareing, Sarah;Mazan, Andrzej;Kouskoff, Valerie
在胚胎发育过程中，造血和血管发生的出现是紧密相关的，许多转录因子参与了这两个发育过程。在这些因素中，ETV 2处于层次结构的顶端，控制着两个谱系的形成。然而，尚不清楚ETV 2在中胚层发育的哪个阶段起作用，以及一旦中胚层前体被指定为造血和内皮命运，是否还需要ETV 2活性。在这项研究中，我们表征了ETV 2表达是造血和内皮发育所需的发育窗口。使用cre介导的ETV 2的缺失，我们证明了ETV 2在中胚层前体中FLK 1表达之前或表达时起作用，以启动造血和内皮程序。使用胚胎干细胞的体外分化作为模型系统，我们进一步表明ETV 2在Etv 2（-/-）Flk 1阴性前体中的再表达驱动造血特化并开启已知与造血和内皮发育有关的大多数基因的表达。在ETV 2的下游靶点中，我们鉴定了已知操作控制造血发育的递归循环的转录因子SCL、GATA 2和FLI 1。令人惊讶的是，SCL在Etv 2（-/-）细胞中的再表达完全拯救了造血，而FLI 1或GATA 2的再表达仅促进了非常有限的拯救。总之，我们的数据确定，ETV 2是非常短暂的指定造血和血管发生的中胚层前体，SCL是ETV 2控制造血特化的关键下游靶标之一。干细胞2012;30：1521-1531
During embryonic development, the emergence of hematopoiesis and vasculogenesis is tightly associated, with many transcription factors implicated in both developmental processes. Among those factors, ETV2 acts at the top of the hierarchy and controls the formation of both lineages. However, it is not known at which stage of mesoderm development ETV2 is acting and whether ETV2 activity is further required once mesodermal precursors have been specified to the hematopoietic and endothelial fates. In this study, we characterize the developmental window during which ETV2 expression is required for hematopoietic and endothelial development. Using cre-mediated deletion of ETV2, we demonstrate that ETV2 is acting prior to or at the time of FLK1 expression in mesodermal precursors to initiate the hematopoietic and endothelial program. Using the in vitro differentiation of embryonic stem cells as a model system, we further show that ETV2 re-expression in Etv2(-/-) Flk1-negative precursors drives hematopoiesis specification and switches on the expression of most genes known to be implicated in hematopoietic and endothelial development. Among the downstream targets of ETV2, we identify the transcription factors SCL, GATA2, and FLI1 known to operate a recursive loop controlling hematopoietic development. Surprisingly, SCL re-expression in Etv2(-/-) cells fully rescues hematopoiesis, while the re-expression of FLI1 or GATA2 promotes only a very limited rescue. Altogether, our data establish that ETV2 is required very transiently to specify mesodermal precursors to hematopoiesis and vasculogenesis and that SCL is one of the key downstream targets of ETV2 in controlling hematopoietic specification. STEM CELLS 2012;30:1521-1531