Functional characterization of zinc transport genes in drosophila melanogaster
2017-02-17T02:21:54Z (GMT) by
The heavy metal zinc is an essential component of the human diet and is incorporated as a structural component in up to 10% of all mammalian proteins. The physiological importance of zinc homeostasis at the cellular level and the molecular mechanisms involved in this process has become topics of increasing interest in recent years. Using the Gal4-UAS system to carry out both ubiquitous and targeted over expression and suppression studies, I have performed a systematic functional characterization of thirteen out of the seventeen putative Drosophila Zip (SCL39) and ZnT (SLC30) zinc transport genes identified to date. Results from this analysis suggest that that at least six of these thirteen genes are essential for fly viability. In addition, my findings reaffirm the previously proposed function of dZnT63C (dZnT1, CG17723: FBgn005432) as an important zinc efflux protein and indicate that the fly homolog of hZip1, dZip42Cα (CG9428: FBgn0033096), is a strong zinc importer in Drosophila. By combining over expression of dZip42Cα with suppression of dZnT63C in targeted tissues, easily identifiable zinc toxicosis phenotypes were generated. These phenotypes could be rescued or worsened by modifying dietary zinc content. My findings show that a genetically based zinc toxicosis situation can be therapeutically treated or exacerbated by modifications to the diet. In addition, these zinc sensitive modifiable phenotypes were used to further characterize the zinc transporting abilities of other Drosophila zinc transport genes. The results of these phenotypic analyses was supplemented by localization studies, whereby tissue targeted ectopic expression of eGFP fused zinc transport proteins was used to assign general sub-cellular localization patterns to each zinc transporter analyzed. Finally, phenotypic and localization results were taken together to form basic interpretations of Drosophila zinc transporter function and to predict a preliminary model for zinc homeostasis in Drosophila cells.