| Structural highlights
Function
[NEMO_MOUSE] Regulatory subunit of the IKK core complex which phosphorylates inhibitors of NF-kappa-B thus leading to the dissociation of the inhibitor/NF-kappa-B complex and ultimately the degradation of the inhibitor. Its binding to scaffolding polyubiquitin seems to play a role in IKK activation by multiple signaling receptor pathways. Also considered to be a mediator for TAX activation of NF-kappa-B. Could be implicated in NF-kappa-B-mediated protection from cytokine toxicity. Involved in TLR3- and IFIH1-mediated antiviral innate response; this function requires 'Lys-27'-linked polyubiquitination (By similarity).[1] [RNF31_HUMAN] E3 ubiquitin-protein ligase component of the LUBAC complex which conjugates linear ('M-1'-linked) polyubiquitin chains to substrates and plays a key role in NF-kappa-B activation and regulation of inflammation. LUBAC conjugates linear polyubiquitin to IKBKG and RIPK1 and is involved in activation of the canonical NF-kappa-B and the JNK signaling pathways. Linear ubiquitination mediated by the LUBAC complex interferes with TNF-induced cell death and thereby prevents inflammation. LUBAC is proposed to be recruited to the TNF-R1 signaling complex (TNF-RSC) following polyubiquitination of TNF-RSC components by BIRC2 and/or BIRC3 and to conjugate linear polyubiquitin to IKBKG and possibly other components contributing to the stability of the complex. Binds polyubiquitin of different linkage types.[2] [3] [4] [5] [6] [7] [8]
Publication Abstract from PubMed
The LUBAC ubiquitin ligase complex, consisting of HOIL-1L, HOIP, and SHARPIN, specifically generates linear polyubiquitin chains. LUBAC-mediated linear polyubiquitination has been implicated in NF-kappaB activation. NEMO, a component of the IkappaB kinase (IKK) complex, is a substrate of LUBAC, but the precise molecular mechanism underlying linear chain-mediated NF-kappaB activation has not been fully elucidated. Here, we demonstrate that linearly polyubiquitinated NEMO activates IKK more potently than unanchored linear chains. In mutational analyses based on the crystal structure of the complex between the HOIP NZF1 and NEMO CC2-LZ domains, which are involved in the HOIP--NEMO interaction, NEMO mutations that impaired linear ubiquitin recognition activity and prevented recognition by LUBAC synergistically suppressed signal-induced NF-kappaB activation. HOIP NZF1 bound to NEMO and ubiquitin simultaneously, and HOIP NZF1 mutants defective in interaction with either NEMO or ubiquitin could not restore signal-induced NF-kappaB activation. Furthermore, linear chain-mediated activation of IKK2 involved homotypic interaction of the IKK2 kinase domain. Collectively, these results demonstrate that linear polyubiquitination of NEMO plays crucial roles in IKK activation, and that this modification involves the HOIP NZF1 domain and recognition of NEMO-conjugated linear ubiquitin chains by NEMO on another IKK complex.
Mechanism underlying IKK activation mediated by the linear ubiquitin chain assembly complex (LUBAC).,Fujita H, Rahighi S, Akita M, Kato R, Sasaki Y, Wakatsuki S, Iwai K Mol Cell Biol. 2014 Jan 27. PMID:24469399[9]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Li Y, Kang J, Friedman J, Tarassishin L, Ye J, Kovalenko A, Wallach D, Horwitz MS. Identification of a cell protein (FIP-3) as a modulator of NF-kappaB activity and as a target of an adenovirus inhibitor of tumor necrosis factor alpha-induced apoptosis. Proc Natl Acad Sci U S A. 1999 Feb 2;96(3):1042-7. PMID:9927690
- ↑ Kirisako T, Kamei K, Murata S, Kato M, Fukumoto H, Kanie M, Sano S, Tokunaga F, Tanaka K, Iwai K. A ubiquitin ligase complex assembles linear polyubiquitin chains. EMBO J. 2006 Oct 18;25(20):4877-87. Epub 2006 Sep 28. PMID:17006537 doi:10.1038/sj.emboj.7601360
- ↑ Haas TL, Emmerich CH, Gerlach B, Schmukle AC, Cordier SM, Rieser E, Feltham R, Vince J, Warnken U, Wenger T, Koschny R, Komander D, Silke J, Walczak H. Recruitment of the linear ubiquitin chain assembly complex stabilizes the TNF-R1 signaling complex and is required for TNF-mediated gene induction. Mol Cell. 2009 Dec 11;36(5):831-44. doi: 10.1016/j.molcel.2009.10.013. PMID:20005846 doi:10.1016/j.molcel.2009.10.013
- ↑ Tokunaga F, Sakata S, Saeki Y, Satomi Y, Kirisako T, Kamei K, Nakagawa T, Kato M, Murata S, Yamaoka S, Yamamoto M, Akira S, Takao T, Tanaka K, Iwai K. Involvement of linear polyubiquitylation of NEMO in NF-kappaB activation. Nat Cell Biol. 2009 Feb;11(2):123-32. doi: 10.1038/ncb1821. Epub 2009 Jan 11. PMID:19136968 doi:10.1038/ncb1821
- ↑ Gerlach B, Cordier SM, Schmukle AC, Emmerich CH, Rieser E, Haas TL, Webb AI, Rickard JA, Anderton H, Wong WW, Nachbur U, Gangoda L, Warnken U, Purcell AW, Silke J, Walczak H. Linear ubiquitination prevents inflammation and regulates immune signalling. Nature. 2011 Mar 31;471(7340):591-6. doi: 10.1038/nature09816. PMID:21455173 doi:10.1038/nature09816
- ↑ Tokunaga F, Nakagawa T, Nakahara M, Saeki Y, Taniguchi M, Sakata S, Tanaka K, Nakano H, Iwai K. SHARPIN is a component of the NF-kappaB-activating linear ubiquitin chain assembly complex. Nature. 2011 Mar 31;471(7340):633-6. doi: 10.1038/nature09815. PMID:21455180 doi:10.1038/nature09815
- ↑ Ikeda F, Deribe YL, Skanland SS, Stieglitz B, Grabbe C, Franz-Wachtel M, van Wijk SJ, Goswami P, Nagy V, Terzic J, Tokunaga F, Androulidaki A, Nakagawa T, Pasparakis M, Iwai K, Sundberg JP, Schaefer L, Rittinger K, Macek B, Dikic I. SHARPIN forms a linear ubiquitin ligase complex regulating NF-kappaB activity and apoptosis. Nature. 2011 Mar 31;471(7340):637-41. doi: 10.1038/nature09814. PMID:21455181 doi:10.1038/nature09814
- ↑ Smit JJ, Monteferrario D, Noordermeer SM, van Dijk WJ, van der Reijden BA, Sixma TK. The E3 ligase HOIP specifies linear ubiquitin chain assembly through its RING-IBR-RING domain and the unique LDD extension. EMBO J. 2012 Oct 3;31(19):3833-44. doi: 10.1038/emboj.2012.217. Epub 2012 Aug 3. PMID:22863777 doi:10.1038/emboj.2012.217
- ↑ Fujita H, Rahighi S, Akita M, Kato R, Sasaki Y, Wakatsuki S, Iwai K. Mechanism underlying IKK activation mediated by the linear ubiquitin chain assembly complex (LUBAC). Mol Cell Biol. 2014 Jan 27. PMID:24469399 doi:http://dx.doi.org/10.1128/MCB.01538-13
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