The Drosophila dead ringer gene is required for early embryonic patterningthrough regulation of argos and buttonhead expression

The dead ringer (dri) gene of Drosophila melanogaster is a member of the re cently discovered ARID-box family of eukaryotic genes that encode proteins with a conserved DNA binding domain. dri itself is highly conserved, with s pecific orthologs in the human, mouse, zebrafish and C. elegans genomes, We have generated dri mutant alleles to show that dri is essential for anteri or-posterior patterning and for muscle development in the embryo, Consisten t with the mutant phenotype and the sequence-specific DNA-binding propertie s of its product, dri was found to be essential for the normal early embryo nic expression pattern of several key regulatory genes. In dri mutant embry os, expression of argos in the terminal domains was severely reduced, accou nting for the dri mutant head phenotype, Conversely, buttonhead expression was found to be deregulated in the trunk region, accounting for the appeara nce of ectopic cephalic furrows. Curiously, dri was found also to be requir ed for maintenance of expression of the ventrolateral region of even-skippe d stripe four. This study establishes dri as an essential co-factor in the regulated expression of specific patterning genes during early embryogenesi s.