title: V7 (CD101) ligation inhibits TCR/CD3-induced IL-2 production by blocking Ca2+ flux and nuclear factor of activated T cell nuclear translocation.
abstract: Ligation of the V7 (CD101) molecule on T cells with anti-V7 mAb blocks TCR/CD3-induced proliferation by inhibiting IL-2 transcription. To explore the basis for this observation, we analyzed the effects of V7 ligation on CD3/TCR-induced changes in intracellular free Ca2+ and Ca2+-dependent nuclear factor of activated T cells (NF-AT) translocation to the nucleus, which is required for IL-2 transcription. T cells exposed to anti-V7 mAb fluxed Ca2+ transiently, but did not flux Ca2+ in response to subsequent treatment with anti-CD3; however, they recovered the capacity to flux Ca2+ after treatment with pervanadate, indicating that tyrosine dephosphorylation of a critical V7-related substrate is required in the desensitization process. One such substrate, phospholipase C (PLC)-gamma1, becomes tyrosine phosphorylated on CD3/TCR activation and mediates inositol triphosphate-dependent Ca2+ flux. Co-cross-linking of T cells with anti-CD3 and anti-V7 resulted in selective inhibition of PLC-gamma1 tyrosine phosphorylation, which may explain V7-mediated blockade of anti-CD3-induced Ca2+ flux. Moreover, anti-CD3-induced binding of transcription factors to a consensus NF-AT-binding oligonucleotide, which is dependent on Ca2+, was blocked completely by treatment of the cells with anti-V7, whereas binding to a consensus-activating protein-1 oligonucleotide was unaffected. Western blot analysis of cytoplasmic and nuclear extracts confirmed that anti-V7 prevented nuclear translocation of NF-ATc induced by anti-CD3. We conclude that V7 ligation interferes with T cell activation and IL-2 secretion through a Ca2+ and tyrosine kinase-dependent pathway that inhibits PLC-gamma1 phosphorylation and prevents NF-AT translocation to the nucleus.
authors.affiliation: Department of Pathology, Stanford University School of Medicine, CA 94305, USA.
authors.forename: L R
authors.initials: LR
authors.lastname: Soares
authors.forename: L
authors.initials: L
authors.lastname: Tsavaler
authors.forename: A
authors.initials: A
authors.lastname: Rivas
authors.forename: E G
authors.initials: EG
authors.lastname: Engleman
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology / Q000378:metabolism; D001692:Biological Transport / Q000276:immunology; D002118:Calcium / Q000037:antagonists & inhibitors* / Q000276:immunology / Q000378:metabolism; D002467:Cell Nucleus / Q000276:immunology* / Q000378:metabolism; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006801:Humans; D007376:Interleukin-2 / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics; D008562:Membrane Glycoproteins / Q000276:immunology* / Q000378:metabolism*; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D010766:Phosphorylation; D011485:Protein Binding / Q000276:immunology; D017260:Receptor-CD3 Complex, Antigen, T-Cell / Q000276:immunology / Q000502:physiology*; D013601:T-Lymphocytes / Q000201:enzymology / Q000276:immunology / Q000378:metabolism*; D014157:Transcription Factors / Q000037:antagonists & inhibitors* / Q000378:metabolism; D014158:Transcription, Genetic / Q000276:immunology; D010738:Type C Phospholipases / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; C093213:CD101 antigen, human; D004268:DNA-Binding Proteins; D007376:Interleukin-2; D008562:Membrane Glycoproteins; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D017260:Receptor-CD3 Complex, Antigen, T-Cell; D014157:Transcription Factors; D014443:Tyrosine; D010738:Type C Phospholipases; D002118:Calcium