14-3-3ε positively regulates Ras-mediated signaling in Drosophila

Abstract

We have isolated mutations in the gene encoding a Drosophila 14-3-3ε protein as suppressors of the rough eye phenotype caused by the ectopic expression of RAS1(V12). Using a simple loss-of-function 14-3-3ε mutation, we show that 14-3-3ε acts to increase the efficiency of RAS1 signaling. The 14-3-3ε protein appears to function in multiple RTK pathways, suggesting that it is a general component of RAS1 signaling cascade. Sequence analysis of three dominant-negative alleles defines two regions of 14-3-3ε that participate in RAS1 signaling. We also present evidence that 14-3-3ε and 14- 3-3ζ, two 14-3-3 protein family members, are partially redundant for RAS1 signaling in photoreceptor formation and in animal viability. Our genetic data suggest that 14-3-3ε functions downstream of or parallel to RAF, but upstream of nuclear factors in RAS1 signaling.