Intermediate neural progenitor cells (INPs) need to avoid both dedifferentiation and differentiation during neurogenesis, but the mechanisms are not well understood. In Drosophila, the Ets protein Pointed P1 (PntP1) is required to generate INPs from type II neuroblasts. Here, we investigated how PntP1 promotes INP generation. By generating pntP1-specific mutants and using RNAi knockdown, we show that the loss of PntP1 leads to both an increase in the type II neuroblast number and the elimination of INPs. We show that the elimination of INPs results from premature differentiation of INPs due to the ectopic Prospero expression in newly generated immature INPs (imINP), whereas the increase in the type II neuroblast number results from the dedifferentiation of imINPs due to a loss of Earmuff at later stages of imINP development. Furthermore, reducing Buttonhead enhances the loss of INPs in pntP1 mutants, suggesting that PntP1 and Buttonhead act cooperatively to prevent premature INP differentiation. Our results demonstrate that PntP1 prevents both the premature differentiation and dedifferentiation of INPs by regulating the expression of distinct target genes at different stages of imINP development.
- Received March 7, 2016.
- Accepted July 27, 2016.