Jaffredo Thierry, Bollerot Karine, Sugiyama Daisuke, Gautier Rodolphe, Drevon Cécile
UMR7622, UPMC Paris VI, Paris, France.
Int J Dev Biol. 2005;49(2-3):269-77. doi: 10.1387/ijdb.041948tj.
We review here the development of the hematopoietic system and its relationship to the endothelium, with a special focus on the characterisation of the hemangioblast, the putative ancestor for endothelial cells and hematopoietic cells. Using the avian model, we have traced in vivo the progeny of embryonic endothelial cells and shown that aortic-born hematopoietic cells (known to generate the definitive hematopoietic lineage) derive from endothelial cells in the floor of the aorta. During this process, endothelial cells undergo a switch from endothelial cells to hematopoietic cells characterised by a downgrading of endothelial cell-specific genes and the parallel upgrading of hematopoietic cell-specific genes. Using a similar approach, we have shown that generation of hematopoietic cells from endothelial cells also takes place during mouse embryonic development. We have thoroughly characterised the dynamics of key molecules (several of which we have cloned) specifically expressed by the yolk sac or aortic hemangioblast. The yolk sac hemangioblast is characterized by the specific expression of SCL/Tal-1 and Lmo2, whereas the aortic hemangioblast expresses Runx-1 (a runt domain transcription factor). Finally, we have demonstrated the existence of a new site for hematopoiesis, namely the allantois. Using quail/chick grafts, we show that this embryonic appendage autonomously produces endothelial cells and hematopoietic cells, these latter being endowed with the attributes of the definitive hematopoietic lineage.
我们在此回顾造血系统的发育及其与内皮的关系，特别关注血管生成细胞（内皮细胞和造血细胞的假定祖先）的特征。利用禽类模型，我们在体内追踪了胚胎内皮细胞的后代，并表明源自主动脉的造血细胞（已知可产生定型造血谱系）源自主动脉底部的内皮细胞。在此过程中，内皮细胞经历了从内皮细胞向造血细胞的转变，其特征是内皮细胞特异性基因的下调以及造血细胞特异性基因的平行上调。使用类似的方法，我们还表明在小鼠胚胎发育过程中也发生了从内皮细胞生成造血细胞的过程。我们已经全面表征了卵黄囊或主动脉血管生成细胞特异性表达的关键分子（其中一些我们已克隆）的动态变化。卵黄囊血管生成细胞的特征是特异性表达SCL/Tal-1和Lmo2，而主动脉血管生成细胞则表达Runx-1（一种 runt 结构域转录因子）。最后，我们证明了一个新的造血部位的存在，即尿囊。使用鹌鹑/鸡移植实验，我们表明这个胚胎附属物自主产生内皮细胞和造血细胞，后者具有定型造血谱系的特征。
