An orthogonal proteomic-genomic screen identifies AIM2 as a cytoplasmic DNA sensor for the inflammasome

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Abstract

Cytoplasmic DNA triggers activation of the innate immune system. Although 'downstream' signaling components have been characterized, the DNA-sensing components remain elusive. Here we present a systematic proteomics screen for proteins that associate with DNA, 'crossed' to a screen for transcripts induced by interferon-β, which identified AIM2 as a candidate cytoplasmic DNA sensor. AIM2 showed specificity for double-stranded DNA. It also recruited the inflammasome adaptor ASC and localized to ASC 'speckles'. A decrease in AIM2 expression produced by RNA-mediated interference impaired DNA-induced maturation of interleukin 1β in THP-1 human monocytic cells, which indicated that endogenous AIM2 is required for DNA recognition. Reconstitution of unresponsive HEK293 cells with AIM2, ASC, caspase-1 and interleukin 1β showed that AIM2 was sufficient for inflammasome activation. Our data suggest that AIM2 is a cytoplasmic DNA sensor for the inflammasome.

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Figure 1: Orthogonal genomics and proteomics screen identifying AIM2 as candidate DNA sensor.
Figure 2: AIM2 binds directly and specifically to double-stranded DNA.
Figure 3: AIM2 is part of the inflammasome.
Figure 4: AIM2 is required for DNA-mediated secretion of IL-1β.
Figure 5: AIM2 is sufficient for IL-1β maturation.

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Acknowledgements

We acknowledge O. Hantschel and A. Pichlmair for critical reading of the manuscript, and M. Brehme for help with illustrations. Supported by the Austrian Academy of Sciences (for the Research Center for Molecular Medicine), the GenAU Program of the Austrian Federal Ministry of Science and Research (Austrian Proteomics Platform II (GZ200.145/I-VI/I/2006) and DRAGON (GZ200.142/I-VI/I/2006)), the European Commission (PIEF-GA-2008-220596 to C.B.) and the Austrian Science Fund (FWF W1205 to E.D.).

Author information

T.B. did most of the experiments, developed the experimental design, supervised the project and wrote the manuscript; C.B. contributed to the cloning and did the immunofluorescence excperiments; S.B. and H.J. contributed to experiments; E.D. and G.D. did the initial screen; J.C. supervised the bioinformatics analysis; M.B. did the microarray experiments; M.P. and K.L.B. did the mass spectrometry analysis; and G.S.-F. conceived the overall strategy, cosupervised the project and contributed to writing the manuscript.

Correspondence to Giulio Superti-Furga.

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