title: Thymic CD4 T cell selection requires attenuation of March8-mediated MHCII turnover in cortical epithelial cells through CD83.
abstract: Deficiency of CD83 in thymic epithelial cells (TECs) dramatically impairs thymic CD4 T cell selection. CD83 can exert cell-intrinsic and -extrinsic functions through discrete protein domains, but it remains unclear how CD83's capacity to operate through these alternative functional modules relates to its crucial role in TECs. In this study, using viral reconstitution of gene function in TECs, we found that CD83's transmembrane domain is necessary and sufficient for thymic CD4 T cell selection. Moreover, a ubiquitination-resistant MHCII variant restored CD4 T cell selection in Cd83(-/-) mice. Although during dendritic cell maturation CD83 is known to stabilize MHCII through opposing the ubiquitin ligase March1, regulation of March1 did not account for CD83's TEC-intrinsic role. Instead, we provide evidence that MHCII in cortical TECs (cTECs) is targeted by March8, an E3 ligase of as yet unknown physiological substrate specificity. Ablating March8 in Cd83(-/-) mice restored CD4 T cell development. Our results identify CD83-mediated MHCII stabilization through antagonism of March8 as a novel functional adaptation of cTECs for T cell selection. Furthermore, these findings suggest an intriguing division of labor between March1 and March8 in controlling inducible versus constitutive MHCII expression in hematopoietic antigen-presenting cells versus TECs.
authors: Institute for Immunology, Biomedical Center Munich, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany.
authors: Julia
authors: J
authors: von Rohrscheidt
authors: Institute for Immunology, Biomedical Center Munich, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany.
authors: Elisabetta
authors: 0000-0003-2708-9204
authors: E
authors: Petrozziello
authors: Institute for Immunology, Biomedical Center Munich, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany.
authors: Jelena
authors: J
authors: Nedjic
authors: Institute for Immunology, Biomedical Center Munich, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany.
authors: Christine
authors: C
authors: Federle
authors: Department of Immune Modulation, University Hospital Erlangen, 91052 Erlangen, Germany.
authors: Lena
authors: L
authors: Krzyzak
authors: Department of Biology, Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142.
authors: Hidde L
authors: 0000-0002-1090-6071
authors: HL
authors: Ploegh
authors: Department of Microbiology, Hyogo College of Medicine, Nishinomiya 663-8501, Japan.
authors: Satoshi
authors: 0000-0002-4447-8853
authors: S
authors: Ishido
authors: Department of Immune Modulation, University Hospital Erlangen, 91052 Erlangen, Germany.
authors: Alexander
authors: 0000-0001-7187-6729
authors: A
authors: Steinkasserer
authors: Institute for Immunology, Biomedical Center Munich, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany ludger.klein@med.lmu.de.
authors: Ludger
authors: L
authors: Klein
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000502:physiology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D003713:Dendritic Cells / Q000276:immunology; D004847:Epithelial Cells / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000378:metabolism*; D007136:Immunoglobulins / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D013950:Thymus Gland / Q000276:immunology*; D044767:Ubiquitin-Protein Ligases / Q000502:physiology*; D054875:Ubiquitination; D000097802:CD83 Antigen
chemical_list: D015703:Antigens, CD; D000949:Histocompatibility Antigens Class II; D007136:Immunoglobulins; D008562:Membrane Glycoproteins; D044767:Ubiquitin-Protein Ligases; D000097802:CD83 Antigen; C559132:March8 protein, mouse