During the past decade, major efforts using genomic and genetic approaches have identified two major classes of innate immune receptors for sensing microbial nucleic acids: Toll-like receptors (TLR: TLR3, 7, 8, 9) and retinoic acid-inducible gene I-like helicases (RLH: RIG-I, LGP2, MDA-5). However, genomic and genetic approaches have left a major gap in our understanding on how these receptors bind nucleic acids and whether additional receptors or coreceptors exist. We decided to open this """"""""Black Box"""""""" by taking a biochemical approach to directly isolate and characterize microbial nucleic acid-binding proteins in human plasmacytoid dendritic cells (pDCs) by CpG-DNA pull down and mass spectrometric peptide sequencing experiments. We identified two novel members of the DExD/H-box helicase family DHX36 and DHX9 that specifically bind CpG- A and CpG-B, respectively, in human pDCs. Knocking down DHX36 expression by siRNA in a pDC cell line was associated with over 50% reduction in type 1 IFN responses and abolished IRF7 nuclear translocation induced by CpG-A and knocking down DHX9 expression was associated with a diminished TNF and IL-6 response and blocking of NF-kB p50 nuclear translocation induced by to CpG-B. The DExD/H helicase family has over 50 members. Based on these preliminary data and the fact that the other viral sensors, including RIG- I-like helicases (RIG-I, LGP2, MDA-5) and Dicer, all belong to the DExD/H helicase family, this proposal will test our central hypotheses: 1) the DExD/H-box helicases DHX36 and DHX9 may represent novel TLR9- independent DNA sensors in pDCs;and 2) the DExD/H helicase family (59 members) may play a much broader role in anti-viral innate immunity than previously thought. )

Public Health Relevance

By CpG-DNA pull down and mass spectrometric peptide sequencing, we identified two novel DExD/H- box helicase family members, DHX36 and DHX9, that specifically bind and respond to CpG-A and CpG-B, respectively, in human pDCs. Because many other viral sensors, including RIG-I like helicases (RIG-I, LGP2, MDA-5) and Dicer, all belong to the DExD/H helicase family, this proposal will test our central hypotheses: 1) the DExD/H-box helicases DHX36 and DHX9 may represent novel TLR9-independent DNA sensors in pDCs;and 2) DExD/H helicase family (59 members) may play a much broader role in anti-viral innate immunity than previously thought. )

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
5R37AI091947-03
Application #
8258739
Study Section
Cellular and Molecular Immunology - A Study Section (CMIA)
Program Officer
Palker, Thomas J
Project Start
2011-05-01
Project End
2016-04-30
Budget Start
2012-05-01
Budget End
2013-04-30
Support Year
3
Fiscal Year
2012
Total Cost
$392,000
Indirect Cost
$142,000
Name
Baylor Research Institute
Department
Type
DUNS #
145745022
City
Dallas
State
TX
Country
United States
Zip Code
75204
Sha, Wenwen; Mitoma, Hiroki; Hanabuchi, Shino et al. (2014) Human NLRP3 inflammasome senses multiple types of bacterial RNAs. Proc Natl Acad Sci U S A 111:16059-64
Lu, Hongbo; Lu, Ning; Weng, Leiyun et al. (2014) DHX15 senses double-stranded RNA in myeloid dendritic cells. J Immunol 193:1364-72
Weng, Leiyun; Mitoma, Hiroki; Trichot, Coline et al. (2014) The E3 ubiquitin ligase tripartite motif 33 is essential for cytosolic RNA-induced NLRP3 inflammasome activation. J Immunol 193:3676-82
Sugimoto, Naoshi; Mitoma, Hiroki; Kim, Taeil et al. (2014) Helicase proteins DHX29 and RIG-I cosense cytosolic nucleic acids in the human airway system. Proc Natl Acad Sci U S A 111:7747-52
Liu, Ying; Lu, Ning; Yuan, Bin et al. (2014) The interaction between the helicase DHX33 and IPS-1 as a novel pathway to sense double-stranded RNA and RNA viruses in myeloid dendritic cells. Cell Mol Immunol 11:49-57
Mitoma, Hiroki; Hanabuchi, Shino; Kim, Taeil et al. (2013) The DHX33 RNA helicase senses cytosolic RNA and activates the NLRP3 inflammasome. Immunity 39:123-35
Zhang, Zhiqiang; Bao, Musheng; Lu, Ning et al. (2013) The E3 ubiquitin ligase TRIM21 negatively regulates the innate immune response to intracellular double-stranded DNA. Nat Immunol 14:172-8
Zhang, Zhiqiang; Yuan, Bin; Lu, Ning et al. (2011) DHX9 pairs with IPS-1 to sense double-stranded RNA in myeloid dendritic cells. J Immunol 187:4501-8
Zhang, Zhiqiang; Yuan, Bin; Bao, Musheng et al. (2011) The helicase DDX41 senses intracellular DNA mediated by the adaptor STING in dendritic cells. Nat Immunol 12:959-65