A regulatory role for cytoplasmic YVKM motif in CTLA-4 inhibition of TCR signaling.
CTLA-4 negatively regulates TCR signaling, although the molecular basis for this effect has yet to be elucidated. The cytoplasmic YVKM motif, while binding to phosphatidylinositol 3-kinase, SHP-2 and the AP-1/AP-2 clathrin adaptor complexes, has been reported to play no role in CTLA-4 function. In contrast, in this study, we demonstrate that, although not essential, the YVKM motif contributes to optimal CTLA-4 blockage of TCRzeta or combined TCRzeta/CD28 signaling. Significantly, dependency on the YVKM motif varied with the mode of anti-receptor presentation, where soluble antibody ligation was more dependent on the presence of the motif than immobilized antibody. Previous studies have mainly relied on the use of immobilized antibody. Neither SHP-2 binding, alterations in TCRzeta chain phosphorylation, nor ZAP-70 recruitment was involved in CTLA-4 wild-type or mutant inhibition. Overall, our findings clearly implicate the YVKM motif in optimal CTLA-4 function.
Schneider
H
H
Department of Haematology, Imperial College School of Medicine, Hammersmith Hospital, London, GB, UK.
da Rocha Dias
S
S
Hu
H
H
Rudd
C E
CE
D000069594:Abatacept; D020816:Amino Acid Motifs; D000818:Animals; D000906:Antibodies / Q000276:immunology; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D060908:CTLA-4 Antigen; D003593:Cytoplasm / Q000378:metabolism; D006825:Hybridomas; D018796:Immunoconjugates; D007376:Interleukin-2 / Q000096:biosynthesis; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D017260:Receptor-CD3 Complex, Antigen, T-Cell / Q000276:immunology*; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology*; D051746:ZAP-70 Protein-Tyrosine Kinase
D000906:Antibodies; D015703:Antigens, CD; D000943:Antigens, Differentiation; D060908:CTLA-4 Antigen; C556707:Ctla4 protein, mouse; D018796:Immunoconjugates; D007376:Interleukin-2; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D017260:Receptor-CD3 Complex, Antigen, T-Cell; D011948:Receptors, Antigen, T-Cell; C054979:antigen T cell receptor, zeta chain; D000069594:Abatacept; D019869:Phosphatidylinositol 3-Kinases; D011505:Protein-Tyrosine Kinases; D051746:ZAP-70 Protein-Tyrosine Kinase; C497262:Zap70 protein, mouse; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; C516725:Ptpn11 protein, mouse; C509248:Ptpn6 protein, mouse