title: Aspartate-glutamate-alanine-histidine box motif (DEAH)/RNA helicase A helicases sense microbial DNA in human plasmacytoid dendritic cells.
abstract: Toll-like receptor 9 (TLR9) senses microbial DNA and triggers type I IFN responses in plasmacytoid dendritic cells (pDCs). Previous studies suggest the presence of myeloid differentiation primary response gene 88 (MyD88)-dependent DNA sensors other than TLR9 in pDCs. Using MS, we investigated C-phosphate-G (CpG)-binding proteins from human pDCs, pDC-cell lines, and interferon regulatory factor 7 (IRF7)-expressing B-cell lines. CpG-A selectively bound the aspartate-glutamate-any amino acid-aspartate/histidine (DExD/H)-box helicase 36 (DHX36), whereas CpG-B selectively bound DExD/H-box helicase 9 (DHX9). Although the aspartate-glutamate-alanine-histidine box motif (DEAH) domain of DHX36 was essential for CpG-A binding, the domain of unknown function 1605 (DUF1605 domain) of DHX9 was required for CpG-B binding. DHX36 is associated with IFN-alpha production and IRF7 nuclear translocation in response to CpG-A, but DHX9 is important for TNF-alpha and IL-6 production and NF-kappaB activation in response to CpG-B. Knocking down DHX9 or DHX36 significantly reduced the cytokine responses of pDCs to a DNA virus but had no effect on the cytokine responses to an RNA virus. We further showed that both DHX9 and DHX36 are localized within the cytosol and are directly bound to the Toll-interleukin receptor domain of MyD88 via their helicase-associated domain 2 and DUF domains. This study demonstrates that DHX9/DHX36 represent the MyD88-dependent DNA sensors in the cytosol of pDCs and suggests a much broader role for DHX helicases in viral sensing.
authors.affiliation: Department of Immunology, Center for Cancer Immunology Research, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Taeil
authors.initials: T
authors.lastname: Kim
authors.forename: Shwetha
authors.initials: S
authors.lastname: Pazhoor
authors.forename: Musheng
authors.initials: M
authors.lastname: Bao
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Zhang
authors.forename: Shino
authors.initials: S
authors.lastname: Hanabuchi
authors.forename: Valeria
authors.initials: V
authors.lastname: Facchinetti
authors.forename: Laura
authors.initials: L
authors.lastname: Bover
authors.forename: Joel
authors.initials: J
authors.lastname: Plumas
authors.forename: Laurence
authors.initials: L
authors.lastname: Chaperot
authors.forename: Jun
authors.initials: J
authors.lastname: Qin
authors.forename: Yong-Jun
authors.initials: YJ
authors.lastname: Liu
mesh_terms: D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism / Q000821:virology; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D018899:CpG Islands; D053487:DEAD-box RNA Helicases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004279:DNA, Viral / Q000378:metabolism*; D003713:Dendritic Cells / Q000276:immunology* / Q000378:metabolism / Q000821:virology*; D006801:Humans; D007113:Immunity, Innate; D050839:Interferon Regulatory Factor-7 / Q000378:metabolism; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism; D052002:NF-kappa B p50 Subunit / Q000378:metabolism; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D034741:RNA, Small Interfering / Q000235:genetics; D011990:Receptors, Transferrin / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D004279:DNA, Viral; C494234:IRF7 protein, human; D050839:Interferon Regulatory Factor-7; C507779:MYD88 protein, human; D053594:Myeloid Differentiation Factor 88; D052002:NF-kappa B p50 Subunit; D009363:Neoplasm Proteins; D034741:RNA, Small Interfering; D011990:Receptors, Transferrin; C466988:DHX36 protein, human; C098487:DHX9 protein, human; D053487:DEAD-box RNA Helicases