title: Importance of spliceosomal RNP1 motif for intermolecular T-B cell spreading and tolerance restoration in lupus.
abstract: We previously demonstrated the importance of the RNP1 motif-bearing region 131-151 of the U1-70K spliceosomal protein in the intramolecular T-B spreading that occurs in MRL/lpr lupus mice. Here, we analyze the involvement of RNP1 motif in the development and prevention of naturally-occurring intermolecular T-B cell diversification. We found that MRL/lpr peripheral blood lymphocytes proliferated in response to peptides containing or corresponding exactly to the RNP1 motif of spliceosomal U1-70K, U1-A and hnRNP-A2 proteins. We also demonstrated that rabbit antibodies to peptide 131-151 cross-reacted with U1-70K, U1-A and hnRNP-A2 RNP1-peptides. These antibodies recognized the U1-70K and U1-A proteins, and also U1-C and SmD1 proteins, which are devoid of RNP1 motif. Repeated administration of phosphorylated peptide P140 into MRL/lpr mice abolished T-cell response to several peptides from the U1-70K, U1-A and SmD1 proteins without affecting antibody and T-cell responses to foreign (viral) antigen in treated mice challenged with infectious virus. These results emphasized the importance of the dominant RNP1 region, which seems to be central in the activation cascade of B and T cells reacting with spliceosomal RNP1+ and RNP1- spliceosomal proteins. The tolerogenic peptide P140, which is recognized by lupus patients' CD4+ T cells and known to protect MRL/lpr mice, is able to thwart emergence of intermolecular T-cell spreading in treated animals.
authors.affiliation: Centre National de Recherche Scientifique UPR9021, Institut de Biologie Moléculaire et Cellulaire, 15 rue René Descartes, 67000 Strasbourg, France.
authors.forename: Fanny
authors.initials: F
authors.lastname: Monneaux
authors.forename: Véronique
authors.initials: V
authors.lastname: Parietti
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Briand
authors.forename: Sylviane
authors.initials: S
authors.lastname: Muller
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics / Q000276:immunology; D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D001402:B-Lymphocytes / Q000502:physiology*; D007108:Immune Tolerance / Q000235:genetics* / Q000276:immunology; D008180:Lupus Erythematosus, Systemic / Q000235:genetics* / Q000276:immunology; D051379:Mice; D019463:Mice, Inbred MRL lpr; D008969:Molecular Sequence Data; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000276:immunology; D012261:Ribonucleoproteins; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000276:immunology; D017381:Spliceosomes / Q000235:genetics* / Q000276:immunology; D013601:T-Lymphocytes / Q000502:physiology*
chemical_list: D016601:RNA-Binding Proteins; C082384:RNP1 protein, S cerevisiae; D012261:Ribonucleoproteins; D029701:Saccharomyces cerevisiae Proteins