Mastermind is a Corepressor of Armadillo Transcriptional Activity in Drosophila Melanogaster

Jesse Small, Vassar College '11 and Prof. Jennifer Kennell

The Wingless (Wg) signaling pathway in Drosophila melanogaster is important for regulating proper cell proliferation and growth. When the pathway is in its active state, Wg proteins bind to ligand receptors on the cellular membrane causing a cascade of events within the cytoplasm, one of which is the accumulation of the Arm protein. Arm then forms a complex with T-cell factor (TCF) leading to the activation of transcription of Wg target genes. The interest of our lab was to find genes that regulate this pathway. In a genetic screen, the mastermind (mam) gene was found to be
a potential negative regulator of the Wg pathway. By performing reporter gene assays in Drosophila Kc167 cells, Mam was found to be a corepressor of Arm transcriptional activity. Furthermore, Mam functionally interacted with Arm in a site-specific fashion: Mam decreased Arm transcriptional activity when the N-terminus of Arm was expressed, but had no effect on the C-terminus. Lastly, we initiated immunoprecipitation studies to determine if Mam and Arm physically interact. We hope to further explore the mechanism underlying Mam corepressor activity in future studies.