The Neuropilins: Multifunctional Semaphorin and VEGF Receptors That Modulate Axon Guidance and Angiogenesis

The neuropilin-1 (np1) and neuropilin-2 (np2) receptors function as receptors for the axon guidance factors belonging to the class-3 semaphorin subfamily. In addition, both neuropilins are able to bind to certain heparin-binding splice forms of vascular endothelial growth factor (VEGF), indicating that both neuropilins have roles in the cardiovascular system as well. Gene targeting experiments indicate that np1 does indeed function as an important modulator of VEGF function during vasculogenesis and angiogenesis, but the role of np2 in the cardiovascular system has not been studied in detail as yet. This review focuses on the neuropilins, their interactions, and their biological roles in the nervous and cardiovascular systems.