“Phosphoregulation of Sorting Nexin 1 in the Drosophila Immune System”
Sara Hamadani, Cassandra Blanchette, Shiyu Wang, Avi Rodal
Membrane trafficking is a vital process that cells utilize to transport cargo in vesicles to their destination for numerous biological processes. Retromer is a protein complex responsible for retrieval of cargo proteins from endosomes to the trans-Golgi network, and is composed of a cargo selective complex trimer which associates with a dimer of sorting nexins (SNX). Our lab has evidence that a particular sorting nexin, sorting nexin 1 (SNX1) plays a role in cargo trafficking in the nervous system and that its function and localization may be regulated through phosphorylation. We chose to study phosphoregulation of SNX1 in the Drosophila immune system, as snx1 mutant larvae exhibit cellular immune system activation (Del Signore et al, 2017). In addition, Drosophila immune cells, known as hemocytes, are amenable to genetic manipulations and imaging.
Here, we tested if phosphorylation of SNX1 is important for its function in the cellular immune system of Drosophila, and how phosphorylation of SNX1 impacts its cellular localization. We did not find a significant increase in number of hemocytes in snx1 mutants compared to the control. We did find that snx1 mutants expressing the SNX1(S118A) phosphomutant had significantly higher levels of F-actin than snx1 mutants expressing SNX1(WT) or SNX1(S216A). We also found that levels of SNX1(WT) and SNX1 (S118A) were comparable in hemocyte cells, but that levels of SNX1(S216A) were significantly lower.
Future work assessing functionality of the SNX1 phosphomutants, and a more detailed characterization of the SNX1 wild type and phosphomutants subcellular localization will provide important information regarding the importance of phosphorylation of SNX1 for its functional regulation and localization.
Support: MRSEC REU