A quantitative RNAi screen for JNK modifiers identifies Pvr as a novel regulator of Drosophila immune signaling.
Drosophila melanogaster responds to gram-negative bacterial challenges through the IMD pathway, a signal transduction cassette that is driven by the coordinated activities of JNK, NF-kappaB and caspase modules. While many modifiers of NF-kappaB activity were identified in cell culture and in vivo assays, the regulatory apparatus that determines JNK inputs into the IMD pathway is relatively unexplored. In this manuscript, we present the first quantitative screen of the entire genome of Drosophila for novel regulators of JNK activity in the IMD pathway. We identified a large number of gene products that negatively or positively impact on JNK activation in the IMD pathway. In particular, we identified the Pvr receptor tyrosine kinase as a potent inhibitor of JNK activation. In a series of in vivo and cell culture assays, we demonstrated that activation of the IMD pathway drives JNK-dependent expression of the Pvr ligands, Pvf2 and Pvf3, which in turn act through the Pvr/ERK MAP kinase pathway to attenuate the JNK and NF-kappaB arms of the IMD pathway. Our data illuminate a poorly understood arm of a critical and evolutionarily conserved innate immune response. Furthermore, given the pleiotropic involvement of JNK in eukaryotic cell biology, we believe that many of the novel regulators identified in this screen are of interest beyond immune signaling.
Bond
David
D
Department of Medical Microbiology and Immunology, University of Alberta, Alberta Institute for Viral Immunology, Edmonton, Alberta, Canada.
Foley
Edan
E
D000818:Animals; D002478:Cells, Cultured; D029721:Drosophila Proteins / Q000502:physiology*; D004331:Drosophila melanogaster; D049750:Genome, Insect; D007113:Immunity, Innate; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors*; D016328:NF-kappa B / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000502:physiology*; D015398:Signal Transduction / Q000276:immunology*; D042442:Vascular Endothelial Growth Factors
D029721:Drosophila Proteins; D016328:NF-kappa B; C528169:Pvf2 protein, Drosophila; D042442:Vascular Endothelial Growth Factors; C438368:Pvr protein, Drosophila; D020794:Receptor Protein-Tyrosine Kinases; D048031:JNK Mitogen-Activated Protein Kinases