Retinal homeobox promotes cell growth, proliferation and survival of mushroom body neuroblasts in the Drosophila brain.

Abstract The Drosophila mushroom bodies, centers of olfactory learning and memory in the fly ‘forebrain’, develop from a set of neural stem cells (neuroblasts) that generate a large number of Kenyon cells (KCs) during sustained cell divisions from embryonic to late pupal stage. We show that retinal homeobox ( rx ), encoding for an evolutionarily conserved transcription factor, is required for proper development of the mushroom bodies. Throughout development rx is expressed in mushroom body neuroblasts (MBNBs), their ganglion mother cells (MB-GMCs) and young KCs. In the absence of rx function, MBNBs form correctly but exhibit a reduction in cell size and mitotic activity, whereas overexpress…