title: NF-κB essential modulator (NEMO) interaction with linear and lys-63 ubiquitin chains contributes to NF-κB activation.
abstract: The IκB kinase (IKK) complex acts as a gatekeeper of canonical NF-κB signaling in response to upstream stimulation. IKK activation requires sensing of ubiquitin chains by the essential IKK regulatory subunit IKKγ/NEMO. However, it has remained enigmatic whether NEMO binding to Lys-63-linked or linear ubiquitin chains is critical for triggering IKK activation. We show here that the NEMO C terminus, comprising the ubiquitin binding region and a zinc finger, has a high preference for binding to linear ubiquitin chains. However, immobilization of NEMO, which may be reminiscent of cellular oligomerization, facilitates the interaction with Lys-63 ubiquitin chains. Moreover, selective mutations in NEMO that abolish association with linear ubiquitin but do not affect binding to Lys-63 ubiquitin are only partially compromising NF-κB signaling in response to TNFα stimulation in fibroblasts and T cells. In line with this, TNFα-triggered expression of NF-κB target genes and induction of apoptosis was partially compromised by NEMO mutations that selectively impair the binding to linear ubiquitin chains. Thus, in vivo NEMO interaction with linear and Lys-63 ubiquitin chains is required for optimal IKK activation, suggesting that both type of chains are cooperating in triggering canonical NF-κB signaling.
authors.affiliation: Department of Cellular Signal Integration Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Toxicology, Neuherberg, Germany. daniel.krappmann@helmholtz-muenchen.de
authors.forename: Kamyar
authors.initials: K
authors.lastname: Hadian
authors.forename: Richard A
authors.initials: RA
authors.lastname: Griesbach
authors.forename: Scarlett
authors.initials: S
authors.lastname: Dornauer
authors.forename: Tim M
authors.initials: TM
authors.lastname: Wanger
authors.forename: Daniel
authors.initials: D
authors.lastname: Nagel
authors.forename: Moritz
authors.initials: M
authors.lastname: Metlitzky
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Beisker
authors.forename: Marc
authors.initials: M
authors.lastname: Schmidt-Supprian
authors.forename: Daniel
authors.initials: D
authors.lastname: Krappmann
mesh_terms: D000818:Animals; D017209:Apoptosis; D001665:Binding Sites; D057809:HEK293 Cells; D006801:Humans; D051550:I-kappa B Kinase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008239:Lysine; D051379:Mice; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D016328:NF-kappa B / Q000378:metabolism*; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D015398:Signal Transduction; D012996:Solutions; D013379:Substrate Specificity; D025801:Ubiquitin / Q000737:chemistry* / Q000378:metabolism*
chemical_list: C491731:IKBKG protein, human; D016328:NF-kappa B; D012996:Solutions; D025801:Ubiquitin; D051550:I-kappa B Kinase; D008239:Lysine