Recombinant TCR ligand induces early TCR signaling and a unique pattern of downstream activation.
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.
Wang
Chunhe
C
Department of Neurology, Oregon Health and Science University, Portland, OR 97239, USA.
Mooney
Jeffery L
JL
Meza-Romero
Roberto
R
Chou
Yuan K
YK
Huan
Jianya
J
Vandenbark
Arthur A
AA
Offner
Halina
H
Burrows
Gregory G
GG
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
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