Neural hyperplasia induced by RNA interference with m4/mα gene activity

The E(spl) complex (E(spl)-C) contains three different classes of genes that are downstream of Notch signaling. The bHLH genes mediate the Notch signal by repressing proneural gene activity, for example during the singularization of mechanosensory organ precursor cells (SOPs). Genes of the second class, the E(spl) m4/ma family, antagonize this process if overexpressed. Here we show that this is based on dominant-negative effects since RNA interference gives neurogenic phenotypes indistinguishable from E(spl)-C mutations. Furthermore, a third member of the m4/ma gene family, named bbu/tom, behaves differently with respect to RNA expression patterns, its regulation by Notch signaling and loss of function phenotypes. q 2000 Elsevier Science Ireland Ltd. All rights reserved.