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.

Nyckelord

Adaptor Proteins; Signal Transducing/*genetics/metabolism

Amino Acid Sequence

Animals

Base Sequence

Blotting; Western

Cells; Cultured

DNA/genetics

DNA Primers

Drosophila Proteins/*genetics/immunology/*metabolism

Drosophila melanogaster/*genetics/immunology/microbiology

Electrophoresis; Polyacrylamide Gel

Escherichia coli/immunology

Gene Library

Immunohistochemistry

Inhibitor of Apoptosis Proteins/*genetics/metabolism

Insect Proteins/metabolism

Luciferases

Models; Biological

Molecular Sequence Data

Oligonucleotide Array Sequence Analysis

Polymerase Chain Reaction

RNA Interference

Reverse Transcriptase Polymerase Chain Reaction

Sequence Analysis; DNA

Signal Transduction/*genetics/immunology

Publikations- och innehållstyp

ref (ämneskategori)

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