D. Fambrough et Cs. Goodman, THE DROSOPHILA BEATEN PATH GENE ENCODES A NOVEL SECRETED PROTEIN THATREGULATES DEFASCICULATION AT MOTOR AXON CHOICE POINTS, Cell, 87(6), 1996, pp. 1049-1058
In the Drosophila embryo, at specific choice points along the major mo
tor nerves, subsets of motor axons defasciculate and then steer into t
heir muscle target regions. Here we describe the analysis of beaten pa
th (beat), a gene required for the selective defasciculation of motor
axons at these choice points. In beat mutant embryos, motor axons fail
to defasciculate and bypass their targets. This phenotype is suppress
ed by mutations in FasII and conn, two genes encoding cell adhesion mo
lecules expressed on motor axons, suggesting that beat provides an ant
iadhesive function. beat encodes a novel secreted protein that is expr
essed by motoneurons during outgrowth. Rescue and ectopic expression e
xperiments support the model that Beat protein is secreted by motor ax
ons where it functions to regulate their selective defasciculation at
specific choice points.