The synaptic proteins Neurexins and Neuroligins are widely expressed in the vascular system and contribute to its functions

Unlike other neuronal counterparts, primarysynaptic proteins are not known to be involved invascular physiology.Here, we demonstrate that Neurexins and Neuroligins, whichconstitute large and complex families of fundamental players in synaptic activity,are produced and processed by endothelial and vascular smooth muscle cells throughout the vasculature. Moreover, they are dynamically regulated during vessel remodeling and form endogenous complexes in large vessels as well as in the brain. We then used the chicken chorioallantoic membrane as a system to pursue functional studies and demonstrate that a monoclonal recombinant antibody against beta Neurexin inhibits angiogenesis while exogenous Neuroligin has a role in promoting it. Finally, as an insight into the mechanism of action of betaNeurexin, we show that the anti beta NRXN antibody influences vessel tone in isolated chicken arteries. Ourdiscovery strongly supportsthe idea that even the mostcomplex and plasticeventstaking place inthe nervous system, i.e. synaptic activity, share molecular cues with the vascular system.