Roles of the TRAF6 and Pellino E3 ligases in MyD88 and RANKL signaling

It is widely accepted that the essential role of TRAF6 in vivo is to generate the Lys63-linked ubiquitin (K63-Ub) chains needed to activate the "master" protein kinase TAK1. Here, we report that TRAF6 E3 ligase activity contributes to but is not essential for the IL-1-dependent formation o...

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Veröffentlicht in:Proceedings of the National Academy of Sciences - PNAS Jg. 114; H. 17; S. E3481
Hauptverfasser: Strickson, Sam, Emmerich, Christoph H, Goh, Eddy T H, Zhang, Jiazhen, Kelsall, Ian R, Macartney, Thomas, Hastie, C James, Knebel, Axel, Peggie, Mark, Marchesi, Francesco, Arthur, J Simon C, Cohen, Philip
Format: Journal Article
Sprache:Englisch
Veröffentlicht: United States 25.04.2017
Schlagworte:
Amino Acid Substitution
Animals
Gene Knockdown Techniques
HEK293 Cells
Humans
Intracellular Signaling Peptides and Proteins
MAP Kinase Kinase Kinases - genetics
MAP Kinase Kinase Kinases - metabolism
Mice
Mice, Knockout
Mutation, Missense
Myeloid Differentiation Factor 88 - genetics
Myeloid Differentiation Factor 88 - metabolism
Nuclear Proteins - genetics
Nuclear Proteins - metabolism
Polyubiquitin - genetics
Polyubiquitin - metabolism
RANK Ligand - genetics
RANK Ligand - metabolism
Signal Transduction
TNF Receptor-Associated Factor 6 - genetics
TNF Receptor-Associated Factor 6 - metabolism
Ubiquitin-Protein Ligases - genetics
Ubiquitin-Protein Ligases - metabolism
Ubiquitin
TAK1
IL-1
Pellino
TRAF6
ISSN:1091-6490, 1091-6490
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Zusammenfassung:It is widely accepted that the essential role of TRAF6 in vivo is to generate the Lys63-linked ubiquitin (K63-Ub) chains needed to activate the "master" protein kinase TAK1. Here, we report that TRAF6 E3 ligase activity contributes to but is not essential for the IL-1-dependent formation of K63-Ub chains, TAK1 activation, or IL-8 production in human cells, because Pellino1 and Pellino2 generate the K63-Ub chains required for signaling in cells expressing E3 ligase-inactive TRAF6 mutants. The IL-1-induced formation of K63-Ub chains and ubiquitylation of IRAK1, IRAK4, and MyD88 was abolished in TRAF6/Pellino1/Pellino2 triple-knockout (KO) cells, but not in TRAF6 KO or Pellino1/2 double-KO cells. The reexpression of E3 ligase-inactive TRAF6 mutants partially restored IL-1 signaling in TRAF6 KO cells, but not in TRAF6/Pellino1/Pellino2 triple-KO cells. Pellino1-generated K63-Ub chains activated the TAK1 complex in vitro with similar efficiently to TRAF6-generated K63-Ub chains. The early phase of TLR signaling and the TLR-dependent secretion of IL-10 (controlled by IRAKs 1 and 2) was only reduced modestly in primary macrophages from knockin mice expressing the E3 ligase-inactive TRAF6[L74H] mutant, but the late-phase production of IL-6, IL-12, and TNFα (controlled only by the pseudokinase IRAK2) was abolished. RANKL-induced signaling in macrophages and the differentiation of bone marrow to osteoclasts was similar in TRAF6[L74H] and wild-type cells, explaining why the bone structure and teeth of the TRAF6[L74H] mice was normal, unlike TRAF6 KO mice. We identify two essential roles of TRAF6 that are independent of its E3 ligase activity.
Bibliographie:ObjectType-Article-1
SourceType-Scholarly Journals-1
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content type line 23
ISSN:1091-6490
1091-6490
DOI:10.1073/pnas.1702367114