Characterization of dSH3PX1 in Drosophila melanogaster

The aim of my exchange in Tom Neufelds lab is to study the role of the SNX18 fly homolog dSH3PX1 in vivo as part of my PhD thesis. The exchange period is scheduled from August 1st 2011 to December 31st 2011 (5 months). The main goal of my PhD thesis is to identify novel PI3P binding proteins required for autophagy. To this end, I have performed a high-trough-put siRNA screen, using a siRNA library designed to individually deplete 80 putative PI3P-binding proteins containing PX or FYVE domains. Since the s uccessful completion of the screen, I am now at the stage of characterizing candidates from the screen in mammalian cell culture experiments. One of the best candidates from the screen is SNX18, a PX and BAR domain containing protein. siRNA-mediated deple tion of this protein strongly inhibits autophagy. It cellular localization is reminiscent of the core autophagic protein mAtg9 and our results show that mAtg9 and SNX18 colocalize. In mammals SNX18 belongs to a family with two closely related family membe rs, SNX9 and SNX33. SNX9 has a well established function in endocytosis. In Drosophila melanogaster, there is only one homolog of the SNX9/18/33 family, called dSH3PX1, which has been shown to function in endocytosis similarly to mammalian SNX9, but its r ole in autophagy has not been studied. This project aims at dissecting the role of dSH3PX1 in autophagy by employing dSH3PX1 mutant fly lines in fat body assays, neurodegeneration assays and by monitoring lifespan. The lab of Tom Neufeld provides the opti mal environment for performing these experiments as it has been one of the major contributors to the field using the fly as a model organism. A stay in his lab gives access to all the best established autophagy assays in flies as well as relevant fly line s and top-end facilities.