Abstract
CpG-ODNs activate dendritic cells (DCs) to produce interferon alpha (IFNα) and beta (IFNβ). Previous studies demonstrated that Toll-like receptor 9 (TLR9) deficient DCs exhibited a residual IFNα response to CpG-A, indicating that yet-unidentified molecules are also involved in induction of IFNα by CpG-A. Here, we report that the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) but not Ku70 deficient BMDCs showed defective IFNα and IFNβ responses to CpG-A or CpG-B. Loss of both DNA-PKcs and TLR9 further reduced the IFNα response to CpG-A. These DNA-PKcs and TLR9 effects were mediated by their downstream Akt/mTORC1 pathway and downstream events IRAK1 and IKKα. Loss of DNA-PKcs, TLR9, MyD88 or IRAK4 impaired phosphorylation of Akt(S473), S6K, S6, IRAK1, or IKKα in BMDCs in response to CpG-ODNs. The residual IFNα and IFNβ in DNA-PKcs-deficient BMDCs were partially responsible for the induction of IL-6 and IL-12 by CpG-ODNs and their stimulatory effect was blocked by IFNAR1 neutralizing antibodies. Further analysis indicated that CpG-ODN associated with DNA-PKcs and Ku70, and induced DNA-PKcs's interaction with TRAF3. Intriguingly, DNA-PKcs but not Ku70 expression level was reduced in TLR9-deficient BMDCs. Taken together, our data suggest that DNA-PKcs is an important mediator in the type I IFN response to CpG-ODNs in TLR9-dependent or -independent fashions.
Publication types
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Research Support, N.I.H., Extramural
MeSH terms
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Animals
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Antigens, Nuclear / immunology
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Antigens, Nuclear / metabolism
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DNA-Activated Protein Kinase / genetics
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DNA-Activated Protein Kinase / metabolism*
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DNA-Binding Proteins / immunology
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DNA-Binding Proteins / metabolism
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Dendritic Cells / drug effects*
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Dendritic Cells / immunology
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Dendritic Cells / metabolism*
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Interferon Type I / pharmacology*
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Interleukin-1 Receptor-Associated Kinases / metabolism
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Interleukin-12 / metabolism
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Interleukin-12 / pharmacology
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Interleukin-6 / metabolism
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Interleukin-6 / pharmacology
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Ku Autoantigen
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Mechanistic Target of Rapamycin Complex 1
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Mice
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Mice, Knockout
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Multiprotein Complexes / metabolism
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Myeloid Differentiation Factor 88 / metabolism
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Oligodeoxyribonucleotides / pharmacology*
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Phosphorylation
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Protein Binding
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Proto-Oncogene Proteins c-akt / metabolism
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STAT1 Transcription Factor / metabolism
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Signal Transduction / drug effects
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TNF Receptor-Associated Factor 3 / metabolism
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TOR Serine-Threonine Kinases / metabolism
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Toll-Like Receptor 9 / genetics
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Toll-Like Receptor 9 / metabolism*
Substances
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Antigens, Nuclear
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CPG-oligonucleotide
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DNA-Binding Proteins
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Interferon Type I
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Interleukin-6
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Multiprotein Complexes
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Myeloid Differentiation Factor 88
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Oligodeoxyribonucleotides
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STAT1 Transcription Factor
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TNF Receptor-Associated Factor 3
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Toll-Like Receptor 9
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Interleukin-12
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DNA-Activated Protein Kinase
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Interleukin-1 Receptor-Associated Kinases
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Mechanistic Target of Rapamycin Complex 1
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Proto-Oncogene Proteins c-akt
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TOR Serine-Threonine Kinases
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Xrcc6 protein, mouse
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Ku Autoantigen