Expression and function of Enhancer of split bHLH proteins during Drosophila neurogenesis.

The products of the Enhancer of split complex are required during neurogenesis for neural fate to be limited to a subset of cells within the ectoderm. Deletions which remove the complex lead to neural hypertrophy. The complex encodes seven related basic-helix-loop-helix transcription factors which are expressed in response to Notch activation. They accumulate in the cells surrounding the delaminating neuroblast where they prevent cells from adopting the neural fate, most likely by antagonising either directly or indirectly the actions of the proneural genes encoded by the achaete-scute complex. The individual roles of the seven different Enhancer of split proteins remains unclear, since their functions are at least partially redundant. However, the Enhancer of split complex is required in many other processes where Notch is active; the function of the individual proteins may relate to their roles in other developmental decisions or to their expression in distinct regions.