Isolation and characterization of five Drosophila genes that encode an ets-related DNA binding domain

Abstract

The recent determination of the site-specific DNA binding properties of several proteins related to the ets oncoprotein has allowed the definition of a novel DNA binding domain, designated the ETS domain. In Drosophila, an ETS domain is present in the early ecdysone-induced E74A protein, which binds DNA in a site-specific manner and interacts with many ecdysone-induced polytene chromosome puffs at the onset of metamorphosis. As a first step toward determining the function of ETS-domain proteins during Drosophila development, we have used PCR amplification with degenerate oligonucleotides to isolate five other ets-related genes. Two of these genes, D- ets-2 and D- elg, have been previously identified. The proteins encoded by these genes are highly related to one another and to the seven identified vertebrate ETS-domain proteins, within the ∼85-amino-acid DNA binding domain. In situ hybridization to polytene chromosomes revealed that these ets-related genes are not clustered in the genome and that only E74 corresponds to an ecdysone-inducible puff locus. These five ets-related genes are distinguished further from E74 in that they are transcribed through most of development, suggesting that they do not perform a stage-specific function. They are, however, expressed in a variety of patterns in early embryos, suggesting roles in the development of specific cell types. D- ets-2 is expressed in a complex pattern that changes dynamically during early embryogenesis. D- ets-3 and D- ets-6 are expressed in the ventral nervous system. The expression of D- ets-3 is higher in the three thoracic segments and lower in the abdominal segments. The high levels of expression in the thoracic segments are dependent on the presence of the bithorax complex. D- ets-4 and D- elg are expressed at their highest levels in the pole cells, suggesting a role in the development of the germline. This study represents the first effort in any organism to systematically isolate members of the ets gene family. The identification of six independent ets-related genes demonstrates that the ETS-domain proteins constitute a new family of potential transcriptional regulators encoded by the Drosophila genome.