Drosophila Rac1 controls motor axon guidance

TLDR

Intersegmental nerve b development requires cell‑surface proteins for proper axon guidance to target muscles. The study demonstrates that the small GTPase Drac1 is essential for intersegmental nerve b axon guidance. Dominant‑negative Drac1 causes axons to bypass normal targets, a phenotype reproduced by blocking actin assembly, and its interaction with Dlar shows that guidance integrates multiple convergent signals.

Abstract

Previous genetic studies of intersegmental nerve b development have identified several cell-surface proteins required for correct axon guidance to appropriate target muscles. Here we provide evidence that the small GTPase Drac1 also plays a key role in this guidance process. Neuronal expression of the dominant negative mutation Drac1(N17) causes axons to bypass and extend beyond normal synaptic partners. This phenotype is consistently reproduced by pharmacological blockade of actin assembly. Genetic interactions between Drac1(N17) and the receptor-tyrosine phosphatase Dlar suggest that intersegmental nerve b guidance requires the integration of multiple, convergent signals.