Biphasic control of nuclear factor-kappa B activation by the T cell receptor complex: role of tumor necrosis factor alpha.
The regulation of nuclear factor (NF)-kappa B activation by the T cell receptor (TcR)/CD3 complex in primary human T cells has been studied at various times after activation. Only p50 NF-kappa B protein bound the kappa B element of interleukin-2 receptor (IL-2R) alpha chain promoter on resting T cells. However, immediately after TcR/CD3 cross-linking (after approximately 1 h; immediate) binding of p50.p65 heterodimers was observed. p50.c-rel heterodimers were also detected bound to this sequence at early time points (7-16 h; early), and both remained active at later time points (40 h; late) after activation. This regulation takes place mainly at the level of nuclear translocation of p65 and c-rel, at immediate and early time points. Activation also induced c-rel and p105/p50 mRNA synthesis, but not p65 mRNA whose expression was constitutive. Interestingly, all those early and late events, but not the immediate ones, were inhibited by a neutralizing anti-tumor necrosis factor alpha (TNF-alpha) monoclonal antibody. Similarly, cycloheximide prevented the p65 and c-rel translocation and consequent formation of active binding heterodimers, at early and late times. Cyclosporin A impaired not only early and late, but also immediate events; however, addition of TNF-alpha prevented all inhibition. These results indicate that the regulation of NF-kappa B activation during T cell activation by TcR/CD3 signals is biphasic: TcR/CD3 triggers its immediate translocation, which is transient if no TNF-alpha is present. TNF-alpha, therefore, emerges as the main factor responsible for a second phase of NF-kappa B regulation, controlling both translocation of p65 and c-rel, and new mRNA synthesis for c-rel and p105/p50.
Centro de Biología Molecular CSIC-UCAM, Madrid, Spain.
F X
FX
Pimentel-Muiños
J
J
Mazana
M
M
Fresno
D000911:Antibodies, Monoclonal; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D016572:Cyclosporine / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D006801:Humans; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000096:biosynthesis*; D017260:Receptor-CD3 Complex, Antigen, T-Cell / Q000276:immunology*; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology*
D000911:Antibodies, Monoclonal; D016328:NF-kappa B; D017260:Receptor-CD3 Complex, Antigen, T-Cell; D014409:Tumor Necrosis Factor-alpha; D016572:Cyclosporine; D003513:Cycloheximide