Immunity
Volume 39, Issue 1, 25 July 2013, Pages 123-135
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Article
The DHX33 RNA Helicase Senses Cytosolic RNA and Activates the NLRP3 Inflammasome

https://doi.org/10.1016/j.immuni.2013.07.001Get rights and content
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Highlights

  • Gene targeting of DHX33 abolishes cytosolic RNA-induced inflammasome activation

  • DHX33 binds viral double-stranded RNA directly via its helicase C domain

  • DHX33 binds NLRP3 via the DEAD domain of DHX33 and the NACHT domain of NLRP3

  • DHX33 forms inflammasome complex with NLRP3 after stimulation with cytosolic dsRNA

Summary

The NLRP3 inflammasome plays a major role in innate immune responses by activating caspase-1, resulting in secretion of interleukin-18 (IL-18) and IL-1β. Although cytosolic double-stranded RNA (dsRNA) and bacterial RNA are known to activate the NLRP3 inflammasome, the upstream sensor is unknown. We investigated the potential function of DExD/H-box RNA helicase family members (previously shown to sense cytosolic DNA and RNA to induce type 1 interferon responses) in RNA-induced NLRP3 inflammasome activation. Among the helicase family members tested, we found that targeting of DHX33 expression by short hairpin RNA efficiently blocked the activation of caspase-1 and secretion of IL-18 and IL-1β in human macrophages that were activated by cytosolic poly I:C, reoviral RNA, or bacterial RNA. DHX33 bound dsRNA via the helicase C domain. DHX33 interacted with NLRP3 and formed the inflammasome complex following stimulation with RNA. We therefore identified DHX33 as a cytosolic RNA sensor that activates the NLRP3 inflammasome.

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