RNA Interference by Short Hairpin RNA Reveals the Role of Jak2a in Blood Vessel Formation of Zebrafish (Danio rerio)

Abstract

Zebrafish (Danio rerio) Jak2a is a homologue of mammalian Jak2. Mammalian Jak2 has been thought to be important in the definitive hematopoiesis, since Jak2-/- transgenic mice are anemic and die around day 12.5 postcoitum due to the lack of adult-type globin gene expression. As an effort to examine the roles of Jak2a during development in zebrafish, we generated Jak2a knock-down embryos by micro-injecting short haripin Jak2a RNA into the fertilized embryos and then examined the phenotypic abnormalities during development. Blood circulation was hampered in Jak2a shRNA-injected embryos from 24 hpf and all of embryos was died with enlarged pericardium, shortened body length and defects in some vasculature within 8 dpf. o-dianisidine staining of red blood cells revealed the normal blood island formation but no circulating red blood cells thereafter. Furthermore, blood vessel formation was disturbed in the jak2a knock-down embryos as revealed by alkaline phosphatase staining at 72 hpf. Thus, our data indicate that Zebrafish Jak2a is important in the determination of both definitive hematopoiesis and blood vessel formation