SIGNALING BY WINGLESS IN DROSOPHILA

wingless, a member of the Wnt gene family, is an essential gene for se gmentation in Drosophila, and is also involved in many other patternin g events. The gene encodes a secreted protein that can regulate gene e xpression in adjacent cells. Recently, significant progress has been m ade in elucidating the signal transduction pathway of wingless, mainly by genetic experiments but increasingly also at the biochemical level . While many components of wingless signaling, in particular a recepto r, remain to be identified, our current understanding of wingless path way is more advanced than that of other Wnt genes. We will give an ove rview of the various roles of wingless in development, and we will the n summarize the wingless signaling pathway as it has emerged from gene tic and biochemical studies. Where appropriate, wingless signaling wil l be compared to the activity of vertebrate Wnt proteins. (C) 1994 Aca demic Press, Inc.