title: Dimerization and ubiquitin mediated recruitment of A20, a complex deubiquitinating enzyme.
abstract: A20 is an anti-inflammatory protein linked to multiple human autoimmune diseases and lymphomas. A20 possesses a deubiquitinating motif and a zinc finger, ZF4, that binds ubiquitin and supports its E3 ubiquitin ligase activity. To understand how these activities mediate A20's physiological functions, we generated two lines of gene-targeted mice, abrogating either A20's deubiquitinating activity (Tnfaip3(OTU) mice) or A20's ZF4 (Tnfaip3(ZF4) mice). Both Tnfaip3(OTU) and Tnfaip3(ZF4) mice exhibited increased responses to TNF and sensitivity to colitis. A20's C103 deubiquitinating motif restricted both K48- and K63-linked ubiquitination of receptor interacting protein 1 (RIP1). A20's ZF4 was required for recruiting A20 to ubiquitinated RIP1. A20(OTU) proteins and A20(ZF4) proteins complemented each other to regulate RIP1 ubiquitination and NFκB signaling normally in compound mutant Tnfaip3(OTU/ZF4) cells. This complementation involved homodimerization of A20 proteins, and we have defined an extensive dimerization interface in A20. These studies reveal how A20 proteins collaborate to restrict TNF signaling.
authors.affiliation: Department of Medicine, University of California, San Francisco, San Francisco, CA 94143-0451, USA.
authors.forename: Timothy T
authors.initials: TT
authors.lastname: Lu
authors.forename: Michio
authors.initials: M
authors.lastname: Onizawa
authors.forename: Gianna E
authors.initials: GE
authors.lastname: Hammer
authors.forename: Emre E
authors.initials: EE
authors.lastname: Turer
authors.forename: Qian
authors.initials: Q
authors.lastname: Yin
authors.forename: Ermelinda
authors.initials: E
authors.lastname: Damko
authors.forename: Alexander
authors.initials: A
authors.lastname: Agelidis
authors.forename: Nataliya
authors.initials: N
authors.lastname: Shifrin
authors.forename: Rommel
authors.initials: R
authors.lastname: Advincula
authors.forename: Julio
authors.initials: J
authors.lastname: Barrera
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Malynn
authors.forename: Hao
authors.initials: H
authors.lastname: Wu
authors.forename: Averil
authors.initials: A
authors.lastname: Ma
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003092:Colitis / Q000139:chemically induced / Q000235:genetics; D003546:Cysteine Endopeptidases; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D020690:GTPase-Activating Proteins / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D055503:Protein Multimerization; D015398:Signal Transduction / Q000235:genetics; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination; D016335:Zinc Fingers / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; D020690:GTPase-Activating Proteins; D047908:Intracellular Signaling Peptides and Proteins; C490620:Ralbp1 protein, mouse; D025801:Ubiquitin; D044767:Ubiquitin-Protein Ligases; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3; D003546:Cysteine Endopeptidases; C513261:Tnfaip3 protein, mouse