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Essential cytoplasmic translocation of a cytokine receptor-assembled signaling complex
Journal article   Peer reviewed

Essential cytoplasmic translocation of a cytokine receptor-assembled signaling complex

Atsushi Matsuzawa, Ping-Hui Tseng, Sivakumar Vallabhapurapu, Jun-Li Luo, Weizhou Zhang, Haopeng Wang, Dario A. A Vignali, Ewen Gallagher and Michael Karin
Science (American Association for the Advancement of Science), Vol.321(5889), pp.663-668
08/01/2008
DOI: 10.1126/science.1157340
PMCID: PMC2669719
PMID: 18635759
url
http://doi.org/10.1126/science.1157340View
Open Access

Abstract

Cytokine signaling is thought to require assembly of multi-component signaling complexes at cytoplasmic segments of membrane-embedded receptors, in which receptor-proximal protein kinases are activated. Indeed, CD40, a tumor necrosis factor receptor (TNFR) family member, forms a complex containing adaptor molecules TRAF2 and TRAF3, ubiquitin conjugating enzyme Ubc13, cellular inhibitor of apoptosis proteins 1 and 2 (c-IAP1/2), IκB kinase regulatory subunit IKKγ (also called NEMO) and mitogen-activated protein kinase (MAPK) kinase kinase MEKK1 upon ligation. TRAF2, Ubc13, and IKKγ were required for complex assembly and activation of MEKK1 and MAPK cascades. However, these kinases were not activated unless the multi-component signaling complex translocated from CD40 to the cytosol upon c-IAP1/2-induced degradation of TRAF3. This two-stage signaling mechanism may apply to other innate immune receptors, accounting for spatial and temporal separation of MAPK and IKK signaling.

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