Unravelling the role of aquaporins in blood vessel development

1. 敲除aqp1a。1, aqp8a。1个或两个基因导致斑马鱼躯干节间血管（isv）的不完全形成。这种表型是由于水通道蛋白突变体的发芽血管生成缺陷所致。在发芽血管生成aqp1a。但不是aqp8a。1在背主动脉表达，aqp1a表达。1在尖端细胞和从主动脉背侧突出的内皮细胞（ECs）中表达丰富。在没有aqp1a的情况下。1和aqp8a。在ISV形成过程中，内皮尖端细胞从主动脉背侧突出延迟，尖端细胞速度减慢。同时，Aqp1a的缺失。1和Aqp8a。1导致形成的丝状足数量减少，丝状足长度减少。在没有丝状足的情况下，野生型ECs仍然能够迁移形成isv，而水通道蛋白突变体中的ECs则不能，这表明丝状足介导的迁移和水通道蛋白可能协同作用，促进EC在发芽血管生成过程中的迁移。我们还发现aqp1a的缺失。但不是aqp8a。1导致造血干细胞和祖细胞（HSPCs）形成减少。在斑马鱼中，造血干细胞是由背主动脉腹底的造血内皮细胞出芽产生的。

1. Knockout of aqp1a.1, aqp8a.1 or both genes results in incomplete formation of intersegmental vessels (ISVs) in the zebrafish trunk. This phenotype is due to a defective sprouting angiogenesis in aquaporin mutants.2. During sprouting angiogenesis aqp1a.1 but not aqp8a.1 is expressed in the dorsal aorta, and aqp1a.1 expression is enriched in tip cells and in endothelial cells (ECs) that would be protrude from the dorsal aorta.3. In the absence of aqp1a.1 and aqp8a.1 there is a delay in endothelial tip cell protrusion from the dorsal aorta and a decrease in tip cell velocity during ISV formation. Also, the loss of both Aqp1a.1 and Aqp8a.1 led to a decrease in the number of the formed filopodia as well as a decrease in filopodia length. In the absence of filopodia, wild type ECs are still able to migrate to form ISVs, while ECs in aquaporin mutants are not, suggesting that both filopodia-mediated migration and aquaporins may function synergistically to promote EC migration during sprouting angiogenesis.4. We also found that the loss of aqp1a.1 but not aqp8a.1 results in a decrease of hematopoietic stem and progenitor cells (HSPCs) formation. In the zebrafish, HSPCs are generated through the budding of hemogenic ECs from the ventral floor of the dorsal aorta.