A common mechanism for antenna-to-leg transformation in Drosophila: Suppression of homothorax transcription by four HOM-C genes

The Drosophila HOM-C genes encode transcription factors containing the DNA- binding homeodomain, Mutations in the HOM-C, genes can cause specific homeo tic transformation, suggesting that the HOM-C genes determine segmental ide ntities by acting on different target genes. However, misexpression of seve ral NOM-C genes in the antenna disc causes similar antenna-re-leg transform ations. Here we show that the Scr, Antp, Ubx, and abd-A NOM-C genes all exe rt their effects through a common mechanism: suppressing the transcription of the homothorax (hth) homeobox gene and thereby preventing the nuclear lo calization of the Extradenticle homeodomain protein. We also show that ecto pic hth expression can cause duplication of the proximodistal axis of the a ntenna, suggesting that it is involved in proximodistal development Of the antenna. (C) 1999 Academic Press.