The identity of the receptors for the fly neurotrophins Nt1 and Nt2 has been unclear. This study identifies two members of the Toll receptor superfamily, which is implicated in innate immunity, as the likely candidates. The authors found that, during development in Drosophila melanogaster, Toll6 and Toll7 regulated motor axon targeting and neuron survival and exhibited overlapping or complementary expression patterns to those of Nt1 and Nt2. They also found genetic interactions between the Toll and NT genes, and showed that Nt1 can bind Toll7, whereas Nt2 can bind both Toll6 and Toll7.
McIlroy, G. et al. Toll-6 and Toll-7 function as neurotrophin receptors in the Drosophila melanogaster CNS. Nature Neurosci. http://dx.doi.org/10.1038/nn.3474 (2013)