Inhibitor of apoptosis 2 and TAK1-binding protein are components of the Drosophila Imd pathway.
The Imd signaling cascade, similar to the mammalian TNF-receptor pathway, controls antimicrobial peptide expression in Drosophila. We performed a large-scale RNAi screen to identify novel components of the Imd pathway in Drosophila S2 cells. In all, 6713 dsRNAs from an S2 cell-derived cDNA library were analyzed for their effect on Attacin promoter activity in response to Escherichia coli. We identified seven gene products required for the Attacin response in vitro, including two novel Imd pathway components: inhibitor of apoptosis 2 (Iap2) and transforming growth factor-activated kinase 1 (TAK1)-binding protein (TAB). Iap2 is required for antimicrobial peptide response also by the fat body in vivo. Both these factors function downstream of Imd. Neither TAB nor Iap2 is required for Relish cleavage, but may be involved in Relish nuclear localization in vitro, suggesting a novel mode of regulation of the Imd pathway. Our results show that an RNAi-based approach is suitable to identify genes in conserved signaling cascades.
Kleino
Anni
A
Institute of Medical Technology, University of Tampere, Tampere, Finland.
Valanne
Susanna
S
Ulvila
Johanna
J
Kallio
Jenni
J
Myllymäki
Henna
H
Enwald
Heidi
H
Stöven
Svenja
S
Poidevin
Mickael
M
Ueda
Ryu
R
Hultmark
Dan
D
Lemaitre
Bruno
B
Rämet
Mika
M
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002478:Cells, Cultured; D004247:DNA / Q000235:genetics; D017931:DNA Primers; D029721:Drosophila Proteins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics* / Q000276:immunology / Q000382:microbiology; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000276:immunology; D015723:Gene Library; D007150:Immunohistochemistry; D051034:Inhibitor of Apoptosis Proteins / Q000235:genetics* / Q000378:metabolism; D019476:Insect Proteins / Q000378:metabolism; D008156:Luciferases; D008954:Models, Biological; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D015398:Signal Transduction / Q000235:genetics* / Q000276:immunology
D048868:Adaptor Proteins, Signal Transducing; C111892:DIAP2 protein, Drosophila; D017931:DNA Primers; D029721:Drosophila Proteins; D051034:Inhibitor of Apoptosis Proteins; D019476:Insect Proteins; C508604:TAB2 protein, Drosophila; C039711:attacin antibacterial protein, insect; C439909:imd protein, Drosophila; D004247:DNA; D008156:Luciferases