Neuropilin-2 is required in vivo for selective axon guidance responses to secreted semaphorins

Neuropilins are receptors for class 3 secreted semaphorins, most of which c an function as potent repulsive axon guidance cues. We have generated mice with a targeted deletion in the neuropilin-2 (Npn-2) locus. Many Npn-2 muta nt mice are viable into adulthood, allowing us to assess the role of Npn-2 in axon guidance events throughout neural development. Npn-P is required fo r the organization and fasciculation of several cranial nerves and spinal n erves. In addition, several major fiber tracts in the brains of adult mutan t mice are either severely disorganized or missing. Our results show that N pn-2 is a selective receptor for class 3 semaphorins in vivo and that Npn-1 and Npn-2 are required for development of an overlapping but distinct set of CNS and PNS projections.