title: Mutually Exclusive Roles of SHARPIN in Integrin Inactivation and NF-κB Signaling.
abstract: SHANK-associated RH domain interactor (SHARPIN) inhibits integrins through interaction with the integrin α-subunit. In addition, SHARPIN enhances nuclear factor-kappaB (NF-κB) activity as a component of the linear ubiquitin chain assembly complex (LUBAC). However, it is currently unclear how regulation of these seemingly different roles is coordinated. Here, we show that SHARPIN binds integrin and LUBAC in a mutually exclusive manner. We map the integrin binding site on SHARPIN to the ubiquitin-like (UBL) domain, the same domain implicated in SHARPIN interaction with LUBAC component RNF31 (ring finger protein 31), and identify two SHARPIN residues (V267, L276) required for both integrin and RNF31 regulation. Accordingly, the integrin α-tail is capable of competing with RNF31 for SHARPIN binding in vitro. Importantly, the full SHARPIN RNF31-binding site contains residues (F263A/I272A) that are dispensable for SHARPIN-integrin interaction. Importantly, disrupting SHARPIN interaction with integrin or RNF31 abolishes SHARPIN-mediated regulation of integrin or NF-κB activity, respectively. Altogether these data suggest that the roles of SHARPIN in inhibiting integrin activity and supporting linear ubiquitination are (molecularly) distinct.
authors.affiliation: Turku Centre for Biotechnology, University of Turku, Turku, Finland.|Medical Biotechnology, VTT Technical Research Centre of Finland, Turku, Finland.
authors.forename: Nicola
authors.initials: N
authors.lastname: De Franceschi
authors.affiliation: Turku Centre for Biotechnology, University of Turku, Turku, Finland.|Medical Biotechnology, VTT Technical Research Centre of Finland, Turku, Finland.
authors.forename: Emilia
authors.initials: E
authors.lastname: Peuhu
authors.affiliation: Randall Division of Cell and Molecular Biophysics, King's College London Guy's Campus, London, United Kingdom.
authors.forename: Maddy
authors.initials: M
authors.lastname: Parsons
authors.affiliation: Department of Physics, Tampere University of Technology, Tampere, Finland.
authors.forename: Sami
authors.initials: S
authors.lastname: Rissanen
authors.affiliation: Department of Physics, Tampere University of Technology, Tampere, Finland.|MEMPHYS-Center for Biomembrane Physics, University of Southern Denmark, Odense, Denmark.
authors.forename: Ilpo
authors.initials: I
authors.lastname: Vattulainen
authors.affiliation: MediCity Research Laboratory, University of Turku, Turku, Finland.|Department of Medical Microbiology and Immunology, University of Turku, Turku, Finland.
authors.forename: Marko
authors.initials: M
authors.lastname: Salmi
authors.affiliation: Turku Centre for Biotechnology, University of Turku, Turku, Finland.|Medical Biotechnology, VTT Technical Research Centre of Finland, Turku, Finland.|Department of Biochemistry and Food Chemistry, University of Turku, Turku, Finland.
authors.forename: Johanna
authors.initials: J
authors.lastname: Ivaska
authors.affiliation: Turku Centre for Biotechnology, University of Turku, Turku, Finland.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Pouwels
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D002465:Cell Movement; D006801:Humans; D016023:Integrins / Q000378:metabolism*; D051379:Mice; D008954:Models, Biological; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D015398:Signal Transduction; D044767:Ubiquitin-Protein Ligases
chemical_list: D016023:Integrins; D050505:Mutant Proteins; D016328:NF-kappa B; D009419:Nerve Tissue Proteins; C425287:sharpin; D044767:Ubiquitin-Protein Ligases