title: Posttranslational regulation of I-Ed by affinity for CLIP.
abstract: Several MHC class II alleles linked with autoimmune diseases form unusually low stability complexes with CLIP, leading us to hypothesize that this is an important feature contributing to autoimmune pathogenesis. To investigate cellular consequences of altering class II/CLIP affinity, we evaluated invariant chain (Ii) mutants with varying CLIP affinity for a mouse class II allele, I-E(d), which has low affinity for wild-type CLIP and is associated with a mouse model of spontaneous, autoimmune joint inflammation. Increasing CLIP affinity for I-E(d) resulted in increased cell surface and total cellular abundance and half-life of I-E(d). This reveals a post-endoplasmic reticulum chaperoning capacity of Ii via its CLIP peptides. Quantitative effects on I-E(d) were less pronounced in DM-expressing cells, suggesting complementary chaperoning effects mediated by Ii and DM, and implying that the impact of allelic variation in CLIP affinity on immune responses will be highest in cells with limited DM activity. Differences in the ability of cell lines expressing wild-type or high-CLIP-affinity mutant Ii to present Ag to T cells suggest a model in which increased CLIP affinity for class II serves to restrict peptide loading to DM-containing compartments, ensuring proper editing of antigenic peptides.
authors.affiliation: Program in Immunology, Department of Pediatrics, Stanford University, Stanford, CA 94305, USA.
authors.forename: Cornelia H
authors.initials: CH
authors.lastname: Rinderknecht
authors.forename: Michael P
authors.initials: MP
authors.lastname: Belmares
authors.forename: Tatiana L W
authors.initials: TL
authors.lastname: Catanzarite
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Bankovich
authors.forename: Tyson H
authors.initials: TH
authors.lastname: Holmes
authors.forename: K Christopher
authors.initials: KC
authors.lastname: Garcia
authors.forename: Navreet K
authors.initials: NK
authors.lastname: Nanda
authors.forename: Robert
authors.initials: R
authors.lastname: Busch
authors.forename: Susan
authors.initials: S
authors.lastname: Kovats
authors.forename: Elizabeth D
authors.initials: ED
authors.lastname: Mellins
mesh_terms: D000483:Alleles; D000818:Animals; D017951:Antigen Presentation / Q000276:immunology; D000944:Antigens, Differentiation, B-Lymphocyte / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D000939:Epitopes / Q000276:immunology; D006207:Half-Life; D000949:Histocompatibility Antigens Class II / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D051379:Mice; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D011485:Protein Binding; D017434:Protein Structure, Tertiary
chemical_list: D000944:Antigens, Differentiation, B-Lymphocyte; D000939:Epitopes; D000949:Histocompatibility Antigens Class II; C045084:invariant chain