The Conserved Transcription Factor Kruppel Regulates the Survival and Neurogenesis ofMushroom Body Neuroblasts in Drosophila Adult Brains

In various metazoans, including Drosophila and humans, neural progenitors exit the cell cycle and are eliminated by the end of development, limiting adult neurogenesis. We demonstrate that in Drosophila, the conserved transcription factor Kruppel (Kr) controls neurogenic capacity of a specific subset of neuroblasts that forms the mushroom body (MBNBs), analogous to the mammalian hippocampus. The Irregular facet mutation, which alters Kr expression, and neuroblast-specific Kr depletion allow MBNBs, but not other neuroblasts, to persist beyond development and generate neurons in adult brains. Persisting MBNBs express Imp, an RNA-binding protein that promotes neuroblast proliferation and survival. Our results underscore a critical role for Kr in the developmental control of a specific progenitor population, uncovering a novel mechanism controlling adult neurogenesis.