Jh. Simpson et al., Short-range and long-range guidance by slit and its robo receptors: Robo and robo2 play distinct roles in midline guidance, NEURON, 28(3), 2000, pp. 753-766
Previous studies showed that Roundabout (Robo) in Drosophila is a repulsive
axon guidance receptor that binds to Slit, a repellent secreted by midline
glia. In robe mutants, growth cones cross and recross the midline, while,
in slit mutants, growth cones enter the midline but fail to leave it. This
difference suggests that Slit must have more than one receptor controlling
midline guidance. In the absence of Robe, some other Slit receptor ensures
that growth cones do not stay at the midline, even though they cross and re
cross it. Here we show that the Drosophila genome encodes three Robe recept
ors and that Robe and Robo2 have distinct functions, which together control
repulsive axon guidance at the midline. The robo,robo2 double mutant is la
rgely identical to slit.