Genome-wide RNAi screening implicates the E3 ubiquitin ligase Sherpa in mediating innate immune signaling by Toll in Drosophila adults.
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.
Division of Molecular Genetics, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan.
Hirotaka
H
Kanoh
Division of Molecular Genetics, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan.
Li-Li
LL
Tong
Division of Molecular Genetics, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan. Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency, Tokyo 102-0076, Japan. takayuki.kuraishi@gmail.com kurata@mail.pharm.tohoku.ac.jp.
Takayuki
T
Kuraishi
Division of Molecular Genetics, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan.
Yamato
Y
Suda
Division of Molecular Genetics, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan.
Yoshiki
Y
Momiuchi
Division of Molecular Genetics, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan.
Fumi
F
Shishido
Division of Molecular Genetics, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan. takayuki.kuraishi@gmail.com kurata@mail.pharm.tohoku.ac.jp.
Shoichiro
S
Kurata
D000818:Animals; D029721:Drosophila Proteins / Q000235:genetics / Q000276:immunology*; D004331:Drosophila melanogaster; D055106:Genome-Wide Association Study; D006094:Gram-Positive Bacteria / Q000235:genetics / Q000276:immunology*; D016908:Gram-Positive Bacterial Infections / Q000235:genetics / Q000276:immunology*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000276:immunology; D034741:RNA, Small Interfering / Q000235:genetics / Q000276:immunology*; D025842:SUMO-1 Protein / Q000235:genetics / Q000276:immunology; D051193:Toll-Like Receptors / Q000235:genetics / Q000276:immunology*; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000276:immunology*
D029721:Drosophila Proteins; D034741:RNA, Small Interfering; D025842:SUMO-1 Protein; C068721:Tl protein, Drosophila; D051193:Toll-Like Receptors; D044767:Ubiquitin-Protein Ligases; C079896:pll protein, Drosophila; D017346:Protein Serine-Threonine Kinases