Venous endothelin guides sympathetic innervation of the developing mouse heart.

Abstract

The mechanisms responsible for establishing correct target innervation during organ development are largely unknown. Sympathetic nerves traverse or follow blood vessels to reach their end-organs, suggesting the existence of vascular guidance cues that direct axonal extension. The sinoatrial node and the ventricle of the heart receive sympathetic innervation from the stellate ganglia (STG). Here we show that STG axons follow veins, specifically the superior vena cavae and sinus venosus, to reach these targets. We find that the election of these routes is determined by venous endothelium-derived endothelin-1, acting through its specific receptor Ednra expressed within a subpopulation of STG neurons. Furthermore, we demonstrate that Edn1-Ednra signaling is essential for functional regulation of the heart by sympathetic nerves. Our findings present venous Edn1 as a sympathetic guidance cue, and show how axon guidance mechanisms are coordinated with end-organ morphogenesis.