Homeobox transcription-factor codes control motor-neuron subtype identity and dorsal versus ventral axon guidance in both vertebrate and invertebrate nervous systems [1-4]; however, the specific axon guidance-receptors that are regulated by these transcription factors to control pathfinding are poorly defined. In Drosophila, the Even-skipped (Eve) transcription factor specifies dorsal motor-axon projection  through the regulation of unidentified guidance molecules. The Netrins and their attractive and repulsive receptors DCC and Unc-5, respectively, define important conserved cue and receptor families that control growth-cone guidance . In Drosophila, the Netrins and frazzled (the fly homolog of DCC) contribute to motor-axon guidance [7-9]. Here, using genetics and single-cell mRNA-expression analysis, we show that expression and requirement of different Netrin receptor combinations correlate with distinct dorsal and ventral motor-axon projections in Drosophila. Misexpression of eve dorsalizes ventral axons in part through the upregulation of Unc-5, whereas loss of eve function in two dorsally projecting motor neurons results in aberrant axon projections and a failure to express Unc-5. Our results support a functional link between the expression of distinct Netrin receptor combinations and the transcriptional control of dorsal motor-axon guidance.
All Science Journal Classification (ASJC) codes
- Biochemistry, Genetics and Molecular Biology(all)
- Agricultural and Biological Sciences(all)