The achaete–scute complex proneural genes contribute to neural precursor specification in the Drosophila CNS

Abstract

Background The Drosophilacentral nervous system (CNS) develops from a segmentally reiterated array of 30 neural precursors. Each precursor acquires a unique identity and goes through a stereotyped cell lineage to produce an invariant family of neurons and/or glia. The proneural genes achaete, scuteand lethal of scute are required for neural precursor formation in the DrosophilaCNS, and are expressed in overlapping subsets of ‘proneural cell clusters’ from which a single neural precursor later develops. Vertebrate achaete–scutehomologues are expressed early during neurogenesis, and promote neurogenesis, neuronal development and/or differentiation. The Drosophilaproneural achaete–scutegenes govern neural precursor formation, but their role in specifying neural precursor identity has not been tested.Results Here, we test the role of the Drosophila achaete–scutegenes in specifying neural precursor identity, focusing on the well characterized CNS MP2 precursor. MP2 delaminates from a cluster of achaete–scute-expressing ectodermal cells. In an achaete–scutedouble mutant, MP2 formation was reduced (to 11–14 %) as expected because of the function of proneural genes in promoting neural precursor formation. Surprisingly, we also observed that the developing MP2 precursors were incorrectly specified and acquired traits characteristic of adjacent neural precursors. In rescue experiments, achaeteor scute, but not lethal of scute, completely restored the normal MP2 identity.Conclusions These results demonstrate that the achaete–scute complex genes specify aspects of neural precursor identity in the DrosophilaCNS. Given the phylogenetically conserved function of these genes, our results raise the possibility that achaete–scutehomologues may help specify neural precursor identity in other organisms.