Abstract
Stimulation through the interleukin-1 receptor (IL-1R) and some Toll-like receptors (TLRs) induces ubiquitination of TRAF6 and IRAK-1, signaling components required for NF-kappaB and mitogen-activated protein kinase activation. Here we show that although TRAF6 and IRAK-1 acquired Lys63 (K63)-linked polyubiquitin chains upon IL-1 stimulation, only ubiquitinated IRAK-1 bound NEMO, the regulatory subunit of IkappaB kinase (IKK). The sites of IRAK-1 ubiquitination were mapped to Lys134 and Lys180, and arginine substitution of these residues impaired IL-1R/TLR-mediated IRAK-1 ubiquitination, NEMO binding, and NF-kappaB activation. K63-linked ubiquitination of IRAK-1 required enzymatically active TRAF6, indicating that it is the physiologically relevant E3. Thus, K63-linked polyubiquitination of proximal signaling proteins is a common mechanism used by diverse innate immune receptors for recruiting IKK and activating NF-kappaB.
Publication types
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Research Support, N.I.H., Intramural
MeSH terms
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Animals
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Base Sequence
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Binding Sites
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Cell Line
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Cells, Cultured
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DNA Primers / genetics
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Humans
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I-kappa B Kinase / chemistry
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I-kappa B Kinase / genetics
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I-kappa B Kinase / metabolism
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Interleukin-1 Receptor-Associated Kinases / chemistry*
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Interleukin-1 Receptor-Associated Kinases / genetics
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Interleukin-1 Receptor-Associated Kinases / metabolism*
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Lysine / chemistry
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Mice
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NF-kappa B / metabolism*
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Receptors, Interleukin-1 / genetics
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Receptors, Interleukin-1 / metabolism*
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Recombinant Proteins / chemistry
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Recombinant Proteins / genetics
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Recombinant Proteins / metabolism
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TNF Receptor-Associated Factor 6 / genetics
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TNF Receptor-Associated Factor 6 / metabolism
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Toll-Like Receptor 4 / genetics
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Toll-Like Receptor 4 / metabolism
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Toll-Like Receptors / genetics
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Toll-Like Receptors / metabolism*
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Transfection
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Ubiquitination
Substances
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DNA Primers
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IKBKG protein, human
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NF-kappa B
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Receptors, Interleukin-1
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Recombinant Proteins
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TLR4 protein, human
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TNF Receptor-Associated Factor 6
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Toll-Like Receptor 4
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Toll-Like Receptors
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IRAK1 protein, human
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Interleukin-1 Receptor-Associated Kinases
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I-kappa B Kinase
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Lysine