1. Genome-wide RNAi screening implicates the E3 ubiquitin ligase Sherpa in mediating innate immune signaling by Toll in Drosophila adults
- Author
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Takayuki Kuraishi, Yoshiki Momiuchi, Hirotaka Kanoh, Li Li Tong, Yamato Suda, Fumi Shishido, and Shoichiro Kurata
- Subjects
Ubiquitin-Protein Ligases ,Antimicrobial peptides ,SUMO-1 Protein ,Protein Serine-Threonine Kinases ,Gram-Positive Bacteria ,Biochemistry ,Ubiquitin ,RNA interference ,Animals ,Drosophila Proteins ,RNA, Small Interfering ,Molecular Biology ,Gram-Positive Bacterial Infections ,Genetics ,Innate immune system ,biology ,Toll-Like Receptors ,Signal transducing adaptor protein ,Cell Biology ,biology.organism_classification ,Ubiquitin ligase ,Drosophila melanogaster ,biology.protein ,Drosophila Protein ,Genome-Wide Association Study - Abstract
The Drosophila Toll pathway plays important roles in innate immune responses against Gram-positive bacteria and fungi. To identify previously uncharacterized components of this pathway, we performed comparative, ex vivo, genome-wide RNA interference screening. In four screens, we overexpressed the Toll adaptor protein dMyd88, the downstream kinase Pelle, or the nuclear factor κB (NF-κB) homolog Dif, or we knocked down Cactus, the Drosophila homolog of mammalian inhibitor of NF-κB. On the basis of these screens, we identified the E3 ubiquitin ligase Sherpa as being necessary for the activation of Toll signaling. A loss-of-function sherpa mutant fly exhibited compromised production of antimicrobial peptides and enhanced susceptibility to infection by Gram-positive bacteria. In cultured cells, Sherpa mediated ubiquitylation of dMyd88 and Sherpa itself, and Sherpa and Drosophila SUMO (small ubiquitin-like modifier) were required for the proper membrane localization of an adaptor complex containing dMyd88. These findings highlight a role for Sherpa in Drosophila host defense and suggest the SUMOylation-mediated regulation of dMyd88 functions in Toll innate immune signaling.
- Published
- 2015