Signaling requirements for the expression of the transactivating factor NF-AT in human T lymphocytes.
A protein called nuclear factor of activated T cells (NF-AT) binds to DNA sequences within the enhancer region of the interleukin 2 (IL 2) gene and appears necessary for both the inducibility and T cell specificity of IL 2 expression. IL 2 production is regulated by multiple signals including those generated via activation of the T cell antigen receptor complex (TcR/CD3), CD2 antigen, protein kinase C (PKC) or elevation of intracellular free calcium concentration ([Ca2+]i). We have, therefore, explored the role of these different stimuli in regulating the nuclear expression of NF-AT in human peripheral blood-derived lymphocytes. Results presented herein indicate that maximal expression of NF-AT in T cells requires at least two signals: PKC activation and TcR/CD3 or CD2 triggering, [Ca2+]i increases and TcR/CD3 or CD2 triggering. Data are presented that indicate that either the [Ca2+]i or PKC signal generated via the TcR/CD3 complex would not alone induce NF-AT expression, and that the TcR/CD3 complex probably regulates NF-AT expression because of its ability to regulate multiple intracellular signals in T cells, and not via any single biochemical event. The combination of CD2 mAb GT2/OKT11 used in the present study to trigger the CD2 antigen is able to act in synergy with phorbol 12,13-dibutyrate or ionomycin to induce NF-AT expression. However, these CD2 mAb do not elevate [Ca2+]i or activate PKC, suggesting that signals other than [Ca2+]i or PKC can regulate NF-AT expression in peripheral blood-derived T cells.
Lymphocyte Activation and Surface Biochemistry Laboratory, Imperial Cancer Research Fund, London, GB.
C
C
Hivroz-Burgaud
N A
NA
Clipstone
D A
DA
Cantrell
D015703:Antigens, CD / Q000502:physiology*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000502:physiology*; D018801:CD2 Antigens; D017252:CD3 Complex; D002118:Calcium / Q000502:physiology; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D066298:In Vitro Techniques; D007295:Inositol Phosphates / Q000378:metabolism; D007376:Interleukin-2 / Q000235:genetics*; D015759:Ionomycin / Q000494:pharmacology; D008213:Lymphocyte Activation; D009687:Nuclear Proteins / Q000378:metabolism*; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D011493:Protein Kinase C / Q000502:physiology; D011948:Receptors, Antigen, T-Cell / Q000502:physiology*; D011971:Receptors, Immunologic / Q000502:physiology*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000502:physiology*; D013997:Time Factors
D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D018801:CD2 Antigens; D017252:CD3 Complex; D004268:DNA-Binding Proteins; D007295:Inositol Phosphates; D007376:Interleukin-2; D009687:Nuclear Proteins; D011948:Receptors, Antigen, T-Cell; D011971:Receptors, Immunologic; D015240:Phorbol 12,13-Dibutyrate; D015759:Ionomycin; D011493:Protein Kinase C; D002118:Calcium