The Developmental Role of warthog, the Notch Modifier Encoding Drab6

The warthog (wrt) gene, recovered as a modifier for Notch signaling, was found to encode the Drosophila homologue of rab6, Drab6. Vertebrate and yeast homologues of this protein have been shown to regulate Golgi network to TGN trafficking. To study the function of this protein in the development of a multicellular organism, we analyzed three different warthog mutants. The first was an R62C point mutation, the second a genomic null, and the third was an engineered GTP-bound form. Our studies show, contrary to yeast, that the Drosophila homologue of rab6 is an essential gene. However, it has limited effects on development beyond the larval stage. Only the mechanosensory bristles on the head, notum, and scutellum are affected by warthog mutations. We present models for the modifying effect of Drab6 on Notch signaling.