In vivo analysis of the evolutionary conserved BTD-box domain of the Sp transcription factors in Drosophila

Abstract

The appendages of arthropods and vertebrates are not homologous structures, although the underlying genetic mechanisms that pattern them are highly conserved. Members of the evolutionarily conserved Sp family of transcription factors control appendage development from flies to humans. In Drosophila, the two Sp family members Sp1 and Btd act redundantly in the specification of leg fates and Distalless (Dll) activation. We have previously shown that Sp1 also controls the growth of the leg, in part, though the regulation of Notch activity. This family of Sp transcription factors is characterized by the presence of the BTD-box, a conserved 10 aa long domain next to the tripled-C2H2 zinc finger which function is unknown. We have analyzed in vivo the role of this conserved domain during appendage development by generating specific Sp1 and btd mutant alleles. In addition, we have studied a new role for Sp1 in the specification of leg vs antennal fates. Although the leg and the antenna are morphologically distinct appendages they have been considered serial homologous structures that share a similar developmental program. Thus, variations in this developmental program are responsible for the morphological differences between these two appendages. Our results suggest an important role of Sp1 in the specification of leg vs antennal fates.