The helicase DDX41 senses intracellular DNA mediated by the adaptor STING in dendritic cells

Abstract

The recognition of pathogenic DNA is important to the initiation of antiviral responses. Here we report the identification of DDX41, a member of the DEXDc family of helicases, as an intracellular DNA sensor in myeloid dendritic cells (mDCs). Knockdown of DDX41 expression by short hairpin RNA blocked the ability of mDCs to mount type I interferon and cytokine responses to DNA and DNA viruses. Overexpression of both DDX41 and the membrane-associated adaptor STING together had a synergistic effect in promoting Ifnb promoter activity. DDX41 bound both DNA and STING and localized together with STING in the cytosol. Knockdown of DDX41 expression blocked activation of the mitogen-activated protein kinase TBK1 and the transcription factors NF-κB and IRF3 by B-form DNA. Our results suggest that DDX41 is an additional DNA sensor that depends on STING to sense pathogenic DNA.

Myeloid neoplasms with germline DDX41 mutation

“…However, despite conservation of these domains, DDX41 has not been shown to bind RNA directly and is dispensable for the interferon response induced by poly(I:C) in mouse dendritic cells [44]. ATP binding has been associated with activation of DDX41, where motifs Q and I are crucial for binding [43] and motifs III and VI for hydrolysis of ATP [37] in helicase activity [43].…”

NF-κB activation during intradermal DNA vaccination is essential for eliciting tumor protective antigen-specific CTL responses

“…Most DNA-sensing PRR (DAI, IFI16, AIM2, DHX9) signaling pathways converge in the activation and nuclear translocation of NF-κB to drive the expression of proinflammatory transcriptional targets. To investigate the role of this pathway, we used a plasmid encoding the IκBα-super repressor (IκBα-SR), which functions similarly to endogenous IκBα in its ability to bind and protein 16 (IFI16), 12 leucine rich repeat flightless-interacting protein (LRRFIP1), 13 probable ATP-dependent RNA helicase DDX41 14 and RNA polymerase III, 15 which transcribes dsDNA into double stranded RNA leading to RIG-I activation. However, which of these DNA-sensing signaling pathways promotes the maturation of APCs after DNA electroporation leading to the generation of CTL responses is not fully understood, especially for intradermal vaccination.…”

Binding of bacterial secondary messenger molecule c di-GMP is a STING operation

“…After sensing the ds DNA in myeloid dendritic cells, DDX41 associated with STING and induced IFN I production by activating IRF3/7 and NF-κB. The DEADc domain of DDX41 was shown to bind DNA directly (Zhang et al, 2011). In addition, in vivo binding of DNA by DDX41 was demonstrated using L monocytogenes infected BMDCs as a model.…”

“…STING KO mice die upon infection by HSV-1. More recently, a DExDc helicase, DDX41, was shown to sense pathogen derived ds DNA (Zhang et al, 2011). After sensing the ds DNA in myeloid dendritic cells, DDX41 associated with STING and induced IFN I production by activating IRF3/7 and NF-κB.…”

“…Interestingly, the same DEADc domain that bound DNA was shown to mediate association of DDX41 with STING. Using deletion mapping, the AA 1-154 region of STING was shown to be important for binding DEADc domain of DDX41 and evoking an immune response (Zhang et al, 2011). Thus, STING plays important roles in innate immune responses against cytosolic DNA as PAMPs (Fig.…”