title: Recombinant TCR ligand induces early TCR signaling and a unique pattern of downstream activation.
abstract: Recombinant TCR ligands (RTLs) consisting of covalently linked alpha(1) and beta(1) domains of MHC class II molecules tethered to specific antigenic peptides represent minimal TCR ligands. In a previous study we reported that the rat RTL201 construct, containing RT1.B MHC class II domains covalently coupled to the encephalitogenic guinea pig myelin basic protein (Gp-MBP(72-89)) peptide, could prevent and treat actively and passively induced experimental autoimmune encephalomyelitis in vivo by selectively inhibiting Gp-MBP(72-89) peptide-specific CD4(+) T cells. To evaluate the inhibitory signaling pathway, we tested the effects of immobilized RTL201 on T cell activation of the Gp-MBP(72-89)-specific A1 T cell hybridoma. Activation was exquisitely Ag-specific and could not be induced by RTL200 containing the rat MBP(72-89) peptide that differed by a threonine for serine substitution at position 80. Partial activation by RTL201 included a CD3zeta p23/p21 ratio shift, ZAP-70 phosphorylation, calcium mobilization, NFAT activation, and transient IL-2 production. In comparison, anti-CD3epsilon treatment produced stronger activation of these cellular events with additional activation of NF-kappaB and extracellular signal-regulated kinases as well as long term increased IL-2 production. These results demonstrate that RTLs can bind directly to the TCR and modify T cell behavior through a partial activation mechanism, triggering specific downstream signaling events that deplete intracellular calcium stores without fully activating T cells. The resulting Ag-specific activation of the transcription factor NFAT uncoupled from the activation of NF-kappaB or extracellular signal-regulated kinases constitutes a unique downstream activation pattern that accounts for the inhibitory effects of RTL on encephalitogenic CD4(+) T cells.
authors.affiliation: Department of Neurology, Oregon Health and Science University, Portland, OR 97239, USA.
authors.forename: Chunhe
authors.initials: C
authors.lastname: Wang
authors.forename: Jeffery L
authors.initials: JL
authors.lastname: Mooney
authors.forename: Roberto
authors.initials: R
authors.lastname: Meza-Romero
authors.forename: Yuan K
authors.initials: YK
authors.lastname: Chou
authors.forename: Jianya
authors.initials: J
authors.lastname: Huan
authors.forename: Arthur A
authors.initials: AA
authors.lastname: Vandenbark
authors.forename: Halina
authors.initials: H
authors.lastname: Offner
authors.forename: Gregory G
authors.initials: GG
authors.lastname: Burrows
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017252:CD3 Complex / Q000378:metabolism; D020013:Calcium Signaling / Q000235:genetics / Q000276:immunology*; D004268:DNA-Binding Proteins / Q000378:metabolism; D006168:Guinea Pigs; D015802:HLA-DR2 Antigen / Q000378:metabolism / Q000502:physiology*; D006649:Histocompatibility Antigens / Q000378:metabolism / Q000502:physiology; D006801:Humans; D006825:Hybridomas; D007376:Interleukin-2 / Q000096:biosynthesis; D008024:Ligands; D008213:Lymphocyte Activation / Q000235:genetics; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008969:Molecular Sequence Data; D004676:Myelin Basic Protein / Q000378:metabolism / Q000494:pharmacology*; D016328:NF-kappa B / Q000378:metabolism; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D010446:Peptide Fragments / Q000378:metabolism / Q000494:pharmacology*; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051381:Rats; D011917:Rats, Inbred Lew; D011948:Receptors, Antigen, T-Cell / Q000502:physiology; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000378:metabolism / Q000502:physiology*; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D013601:T-Lymphocytes / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D014407:Tumor Cells, Cultured; D051746:ZAP-70 Protein-Tyrosine Kinase
chemical_list: D017252:CD3 Complex; C121704:CD3 antigen, zeta chain; C115335:CD3E protein, human; D004268:DNA-Binding Proteins; D015802:HLA-DR2 Antigen; D006649:Histocompatibility Antigens; D007376:Interleukin-2; D008024:Ligands; D004676:Myelin Basic Protein; D016328:NF-kappa B; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D010446:Peptide Fragments; D011948:Receptors, Antigen, T-Cell; D016693:Receptors, Antigen, T-Cell, alpha-beta; D011994:Recombinant Proteins; D014157:Transcription Factors; C038353:histocompatibility antigens RT, rat; C116916:myelin basic protein 73-86; D011505:Protein-Tyrosine Kinases; D051746:ZAP-70 Protein-Tyrosine Kinase; C497261:ZAP70 protein, human; C497262:Zap70 protein, mouse; D020928:Mitogen-Activated Protein Kinases