Systematic Nitric Oxide Signals Cardiac Progenitors During Early Cardiogenesis in the Chick Embryo
By: Danielle Peterson
Department: Biology
Faculty Advisor: Dr. Wilfred Denetclaw
Heart development in vertebrates is a precise and complex event involving the proliferation, differentiation, and migration of cardiac progenitor cells (CPCs) which are found in the bilateral heart fields (cardiogenic mesoderm). These processes are regulated by a concert of signaling molecules, occurring in a precise spatio-temporal pattern to bring the heart tubes together to fuse and form the primitive heart, which first manifests at the ventral midline as a linear heart tube consisting of myocardial cells surrounding endothelial cells. However, the identity of these molecules is still being elucidated. Nitric oxide (NO) is a gaseous, pleiotropic signaling molecule that has shown to promote cardiogenesis in mouse and human ESCs in vitro. However, NOs signaling involvement in cardiogenesis in vivo is not well understood. To assess the role that NO plays in embryonic cardiogenesis, we use a fluorescent NO probe, 4,5-diaminofluorescein diacetate (DAF-2 diacetate), during early heart developmental stages in live chicken embryo culture. DAF-2 diacetate demonstrates endogenous NO in a precise-spatiotemporal manner correlating with well-established heart fields. Further support for a role of NO in heart formation was shown by inhibition of NO formation by the nitric oxide synthase inhibitor, L-NAME, in a HH7 to 8- embryo, which resulted in cardia bifida-failure of the bilateral heart tubes to fuse at the midline. Furthermore, treatment with the NO donor, DETA NONOate, at HH8 resulted in larger sized straight heart tubes compared to untreated embryos. These results collectively illustrate systematic signaling involvement of NO in early embryo cardiogenesis events such as CPC differentiation or proliferation, migration, and fusion. Supported by the National Science Foundation (DBI-1548297).