title: Characterization of a Putative Receptor Binding Surface on Skint-1, a Critical Determinant of Dendritic Epidermal T Cell Selection.
abstract: Dendritic epidermal T cells (DETC) form a skin-resident γδ T cell population that makes key contributions to cutaneous immune stress surveillance, including non-redundant contributions to protection from cutaneous carcinogens. How DETC become uniquely associated with the epidermis was in large part solved by the identification of Skint-1, the prototypic member of a novel B7-related multigene family. Expressed only by thymic epithelial cells and epidermal keratinocytes, Skint-1 drives specifically the development of DETC progenitors, making it the first clear candidate for a selecting ligand for non-MHC/CD1-restricted T cells. However, the molecular mechanisms underpinning Skint-1 activity are unresolved. Here, we provide evidence that DETC selection requires Skint-1 expression on the surface of thymic epithelial cells, and depends upon specific residues on the CDR3-like loop within the membrane-distal variable domain of Skint-1 (Skint-1 DV). Nuclear magnetic resonance of Skint-1 DV revealed a core tertiary structure conserved across the Skint family, but a highly distinct surface charge distribution, possibly explaining its unique function. Crucially, the CDR3-like loop formed an electrostatically distinct surface, featuring key charged and hydrophobic solvent-exposed residues, at the membrane-distal tip of DV. These results provide the first structural insights into the Skint family, identifying a putative receptor binding surface that directly implicates Skint-1 in receptor-ligand interactions crucial for DETC selection.
authors.affiliation: From the Cancer Immunology and Immunotherapy Centre, Institute of Immunology and Immunotherapy, University of Birmingham, Edgbaston, Birmingham B15 2TT.
authors.forename: Mahboob
authors.initials: M
authors.lastname: Salim
authors.affiliation: the School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Knowles
authors.affiliation: the Francis Crick Institute, Lincoln's Inn Fields Research Laboratories, London WC2A 3LY, the Peter Gorer Department of Immunobiology, King's College London, London SE1 9RT, United Kingdom.
authors.forename: Rosie
authors.initials: R
authors.lastname: Hart
authors.affiliation: From the Cancer Immunology and Immunotherapy Centre, Institute of Immunology and Immunotherapy, University of Birmingham, Edgbaston, Birmingham B15 2TT.
authors.forename: Fiyaz
authors.initials: F
authors.lastname: Mohammed
authors.affiliation: the Francis Crick Institute, Lincoln's Inn Fields Research Laboratories, London WC2A 3LY, the Peter Gorer Department of Immunobiology, King's College London, London SE1 9RT, United Kingdom.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Woodward
authors.affiliation: From the Cancer Immunology and Immunotherapy Centre, Institute of Immunology and Immunotherapy, University of Birmingham, Edgbaston, Birmingham B15 2TT.
authors.forename: Carrie R
authors.initials: CR
authors.lastname: Willcox
authors.affiliation: the School of Cancer Sciences, University of Birmingham, Henry Wellcome Building for Biomolecular NMR, Edgbaston, Birmingham B15 2TT, and.
authors.forename: Michael
authors.initials: M
authors.lastname: Overduin
authors.affiliation: the Francis Crick Institute, Lincoln's Inn Fields Research Laboratories, London WC2A 3LY, the Peter Gorer Department of Immunobiology, King's College London, London SE1 9RT, United Kingdom.
authors.forename: Adrian C
authors.initials: AC
authors.lastname: Hayday
authors.affiliation: From the Cancer Immunology and Immunotherapy Centre, Institute of Immunology and Immunotherapy, University of Birmingham, Edgbaston, Birmingham B15 2TT, b.willcox@bham.ac.uk.
authors.forename: Benjamin E
authors.initials: BE
authors.lastname: Willcox
mesh_terms: D000818:Animals; D002460:Cell Line; D004817:Epidermis / Q000276:immunology*; D004847:Epithelial Cells / Q000276:immunology*; D006801:Humans; D007136:Immunoglobulins / Q000737:chemistry* / Q000276:immunology*; D051379:Mice; D019906:Nuclear Magnetic Resonance, Biomolecular; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D007136:Immunoglobulins; D016692:Receptors, Antigen, T-Cell, gamma-delta; C529023:Skint1 protein, mouse
keywords: T-cell receptor (TCR); immunology; lymphocyte; nuclear magnetic resonance (NMR); stress