Investigating Human and Drosophila Sprinter Function

Abstract

Within developing tissues, the Wingless (Wg)/Wnt signaling pathway acts as a morphogen, regulating downstream target activation within receiving cells and ensuring proper growth and organization. Our laboratory has identified a novel highly conserved transmembrane protein in Drosophila named Sprinter (Srt) whose specific mechanism of function is unknown, however without it, Wg is retained within secretory cells (1). We hypothesize that Srt functions by supplying a critical activity required for maturation of Wg protein in its route through the secretory pathway. The focus of this research is to begin to characterize Srt function and determine if the mechanism of function is conserved between humans and Drosophila. Compartment localization studies show that the majority of Drosophila and human Srt reside in an undefined secretory compartment and high level Srt expression causes cells to produce processes that appear to contain vesicles of Wg (Figure 1). Furthermore, we have found that Srt exerts its function by direct physical interaction with the Wg protein and that this interaction is conserved across species. These results suggest that Srt is a multifunctional protein that physically interacts with Wg and perhaps promotes cellular morphological changes that support its dissemination from secretory cells. This data also indicates that these functions are conserved across species. Furthermore, these experiments provide the foundation for evaluating Srt function and conservation in developing Drosophila.