A function of Spalt major as a sequence-specific DNA binding transcription factor mediates repression ofknirpsin theDrosophilawing imaginal disc

Abstract

ABSTRACTThe Spalt transcriptional regulators participate in a variety of cell fate decisions during multicellular development. Vertebrate Spalt proteins have been mostly associated to the organization of heterochromatic regions, but they also contribute regulatory functions through binding to A/T rich motives present in their target genes. The developmental processes in which theDrosophila spaltgenes participate are well known through genetic analysis, but the mechanism by which the Spalt proteins regulate transcription are still unknown. Furthermore, despite the prominent changes in gene expression associated to mutations in thespaltgenes, the specific DNA sequences they bind are also unknow. In this contribution we describe the analysis of a DNA fragment present in the regulatory region of theknirpsgene. Spalt proteins are candidate repressors ofknirpsexpression during the formation of the venation pattern in the wing disc, and here we identify a minimal conserved 30bp sequence that binds to Spalt major bothin vivoandin vitro. This sequence mediates transcriptional repression in the central region of the wing blade, constituting the first confirmed case of a direct regulatory interaction between Spalt major and its target DNA inDrosophila.