THE ACTIVITIES OF 2 ETS-RELATED TRANSCRIPTION FACTORS REQUIRED FOR DROSOPHILA EYE DEVELOPMENT ARE MODULATED BY THE RAS/MAPK PATHWAY

We show that the activities of two Ets-related transcription factors required for normal eye development in Drosophila, pointed and yan, are regulated by the Ras1/MAPK pathway. The pointed gene codes for two related proteins, and we show that one form is a constitutive activator of transcription, while the activity of the other form is stimulated by the Ras1/MAPK pathway. Mutation of the single consensus MARK phosphorylation site in the second form abrogates this responsiveness. yan is a negative regulator of photoreceptor determination, and genetic data suggest that it acts as an antagonist of Ras1. We demonstrate that yan can repress transcription and that this repression activity is negatively regulated by the Ras1/MAPK signal, most likely through direct phosphorylation of yan by MAPK.