Collapsin-1/semaphorin D is a repellent for chick ganglion of Remak axons

Chick collapsin-1/human semaphorin III/mouse semaphorin D is believed to gu ide the extension of specific axons by a repellent mechanism. Here we exami ne its role in the guidance of axons elf the ganglion of Remak (Remak) in t he developing chick intestine. Early in embryogenesis Remak axons extend pa rallel to, but do not enter, the intestine when collapsin-1 is expressed in the adjacent rectal wall. Remak axons later penetrate the peripheral porti ons of the rectal wall when collapsin-1 expression retreats from the outer muscle layer to the more internal submucosal and mucosal layers of the rect um. Extension of Remak neurites is repelled in vitro by rectum explants and also by 293T cells expressing collapsin-1. The rectal chemorepellent activ ity is blocked by anti-collapsin-1 antibodies. Our results suggest that col lapsin-1 may help prevent Remak axons from projecting into the intestinal w all at early developmental times and later restricts Remak axon trajectorie s to the outer part of the intestinal muscle layer, (C) 1999 Academic Press .