Nervous vascular parallels: axon guidance and beyond.

The vascular and nervous systems are organized with well defined and accurate networks, which represent the anatomical structure enabling their functions. In recent years, it has been clearly demonstrated that these two systems share in common several mechanisms and specificities. For instance, the networking properties of the nervous and vascular systems are governed by common cues that in the brain regulate axon connections and in the vasculature remodel the primitive plexus towards the vascular tree. Here, we summarize the role of semaphorins as a paradigmatic example of the role of axon guidance molecules in physiological and pathological angiogenesis. Finally, we discuss the presence in blood vessels of neurexin and neuroligin, two proteins that finely modulate synaptic activity in the brain. This observation is suggestive of an intriguing new class of molecular and functional parallels between neurons and vascular cells.