THE DROSOPHILA GENE ALIEN IS EXPRESSED IN THE MUSCLE ATTACHMENT SITESDURING EMBRYOGENESIS AND ENCODES A PROTEIN HIGHLY CONSERVED BETWEEN PLANTS, DROSOPHILA AND VERTEBRATES

We have found a novel gene (alien) that is expressed exclusively in th e muscle attachment sites (apodemes) during embryogenesis in Drosophil a. Antibodies raised against the Alien protein enable us to follow the developing attachments from stage 11/12 until stage 16/17. The coding region of the Drosophila alien gene is highly conserved to a gene of unknown function, isolated from a plant (Loo et al., 1995), and to the human TRIP15 gene (Lee et al., 1995). Searching for thyroid receptor interacting proteins, TRIP15 was isolated as a negative regulator. Whe ther there is a functional correlation to Alien remains to be analyzed . Alien expression is independent of muscle formation, as shown in rol ling stone mutant embryos. Even in twist and snail mutants, lacking me sodermal development, alien expression is fairly normal, showing a rat her autonomous development of the apodemes. The conservation of alien suggests an important role in differentiation.