D-raf in Drosophila Signal Transduction

Iowa State University, Ames IA

Investigators

Abstract

The goal of this project is to define the mechanisms that regulate the activity of D-raf in receptor tyrosinekinase mediated signaling pathways for the establishment and elaboration of pattern in Drosophila melanogaster. Using a structure/function approach we have defined D-raf regulatory domains that are required for signaling in the maternal Torso pathway to specify cell fates at the embryonic poles. Our studies have revealed that transmission of the terminal signal depends on the activity of a novel regulatory branch, termed the "inhibitory branch", which (i) acts in parallel with the Torso receptor tyrosine kinase: (ii) is dependent on the maternal activities of the trunk and fs(1) pole hole genes; and (iii) involves the regulation of D-raf at serine residue 388. The specific aims of this project are as follows: (1) to define similarities and differences in mechanisms of regulation by expressing D-raf domains in Torso and Drosophila EGFR pathways. (2) to begin a saturation screen for mutations affecting the "inhibitory branch" of the terminal signaling pathway. (3) to complete a two-hybrid screen using the D-rafCR2 module (conserved region 2) containing serine 388 to identify "inhibitory branch" factor(s) that interact with D-raf. Since D-raf is the Drosophila homologue of the Raf-1 proto-oncogene, characterization of its role in development and identification of the mechanisms involved in its regulation will provide clues to understand the process of signal transduction in higher organisms.