Midline crossing requires Comm's redirecting of Robo.

Dickson/Elsevier

Rapid rerouting of intracellular traffic is responsible for the axon guidance of certain fly neurons, according to Krystyna Keleman, Barry Dickson (Research Institute of Molecular Pathology, Vienna, Austria), and colleagues.

The neurons do not spend their whole time crossing and recrossing the midline of the fly because the midline repellent Slit binds the Robo receptor. Now, Dickson and colleagues show that crossing events require that the guidance protein Comm grab onto Robo in the Golgi and send it on a suicide journey to late endosomes and lysosomes. This eliminates the influence of Slit, allowing neurons to cross. After crossing, Comm is rapidly turned off to reestablish Robo signaling and prevent recrossing.

In the few cases studied, Comm transcription turns on just as neurons initiate their turn toward the midline. This is probably controlled by cell fate determinants...

The Rockefeller University Press
2002
The Rockefeller University Press
2002
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