The identity of individual segments in the fruit fly, Drosophila melanogaster, is regulated by the expression of the homeotic genes within specific segments. These homeotic genes encode transcription factors that regulate segment specific expression of other morphogenetic genes. Homologs of many Drosophila homeotic genes have been identified throughout much of the animal kingdom, where they are often expressed in analogous portions of the embryonic body plan. Analysis of the roles of the Drosophila homeotlc genes and of the interrelationships among these genes during Drosophila embryology is likely to provide important developmental principles involved generally in animal embryology. The cap'n'collar (cnc) gene of Drosophila is a homeotic gene that is important in defining the identity of the mandibular and labral segments during embryonic development. Unlike most other homeotic genes which encode monomeric DNA-binding proteins, cnc is unique in encoding a subunit of a dimeric bZIP transcription factor. The research proposed here will continue the analysis of the role of this gene in Drosophila development, of the Dlochemical mechanisms of its function and of its interaction with the Drosophila bZIP gene, mat2. In particular, this study will characterize the developmental function of mat2 by mutational analysis and ectopic expression, investigate the ability of the CNC protein to form functional heterodimers with other Drosophila bZIP proteins, identify the enhancer regions controlling cnc spatial expression and investigate the role of cnc in oogenesis. This study will also isolate and characterize cnc-like genes from zebrafish, in order to elucidate whether the homeotlc function of cnc is evolutionarily conserved to vertebrates.
