title: Modification of the inflammatory mediator LRRFIP2 by the ubiquitin-like protein FAT10 inhibits its activity during cellular response to LPS.
abstract: FAT10 is a ubiquitin-like protein made of two tandem, head-to-tail, ubiquitin domains. It is known to covalently modify proteins in a mechanism similar, though not identical, to that of other ubiquitin-like proteins. The lack of known physiological substrates covalently conjugated by the protein made it difficult to unravel its biological functions. Here we identify two proteins that are covalently modified by FAT10, the inflammatory mediator LRRFIP2 and the endoplasmic reticulum membrane protein LULL1. LRRFIP2 is involved in NF-κB activation following stimulation of TLR4. It is recruited along with MYD88 to the cytosolic tail of the receptor, and by that mediates activation of the downstream signaling cascade. We show that FATylation of LRRFIP2 occurs on two distinct sites, each being modified by a single FAT10 moiety. Furthermore, the second modification is regulated by the first one. Importantly, FATylation of LRRFIP2 interferes with its recruitment to the membrane by translocating it to the cellular insoluble fraction, thus inhibiting NF-κB activation.
authors.affiliation: Center for Vascular and Tumor Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 31096, Israel. c_tzachy@netvision.net.il
authors.forename: Samuel
authors.initials: S
authors.lastname: Buchsbaum
authors.forename: Beatrice
authors.initials: B
authors.lastname: Bercovich
authors.forename: Tamar
authors.initials: T
authors.lastname: Ziv
authors.forename: Aaron
authors.initials: A
authors.lastname: Ciechanover
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D007249:Inflammation / Q000276:immunology* / Q000378:metabolism; D008070:Lipopolysaccharides / Q000276:immunology*; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D009154:Mutation; D016328:NF-kappa B / Q000378:metabolism; D013379:Substrate Specificity; D051197:Toll-Like Receptor 4 / Q000276:immunology; D054875:Ubiquitination; D014452:Ubiquitins / Q000235:genetics / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C120550:LRRFIP2 protein, human; D008070:Lipopolysaccharides; D008565:Membrane Proteins; D016328:NF-kappa B; C495345:TLR4 protein, human; C500006:TOR1AIP2 protein, human; D051197:Toll-Like Receptor 4; C109184:UBD protein, human; D014452:Ubiquitins