Loss of wwox expression in zebrafish embryos causes edema and alters Ca2+ dynamics

We investigated the role of the WW domain-containing oxidoreductase (wwox) gene in the embryonic development of zebrafish, with particular emphasis on intracellular Ca2+ dynamics because Ca2+ is an important intracellular messenger. Comparisons between zebrafish wwox and human WWOX sequences identified highly conserved domain structures. wwox was expressed in developing heart tissues in the zebrafish embryo. Moreover, wwox knockdown induced pericardial edema with similarities to conditions observed in human breast cancer. The wwox knockdown embryos with the edema died within a week. High Ca2+ levels were observed at the boundary between the edema and yolk in wwox knockdown embryos.