NF-AT(p), a T lymphocyte DNA-binding protein that is a target for calcineurin and immunosuppressive drugs

P. G. McCaffrey, B. A. Perrino, T. R. Soderling, A. Rao

    Research output: Contribution to journalArticle

    257 Scopus citations

    Abstract

    The nuclear factor of activated T cells (NF-AT) is essential for transcription of the interleukin-2 gene upon T cell activation. Here we use a technique involving elution and renaturation of proteins from SDS-acrylamide gels to identify a DNA-binding component of NF-AT (NF-AT(p)) that is present in hypotonic extracts of T cells prior to activation and appears in nuclear extracts when T cells are activated. NF-AT(p) is present in resting T cells predominantly in a form migrating with an apparent molecular weight of 110,000-140,000, while NF-AT(p) from nuclear extracts of activated T cells migrates with a lower apparent molecular weight (90,000-125,000). This difference is likely to reflect dephosphorylation of NF-AT(p), since treatment of NF-AT(p) with calf intestinal phosphatase or the calcium- and calmodulin-dependent phosphatase calcineurin in vitro results in a similar decrease in its apparent molecular weight. We show that NF-AT(p) is dephosphorylated in cell lysates by a calcium-dependent process that is blocked by inclusion of EGTA or a specific peptide inhibitor of calcineurin in the cell lysis buffer. Moreover, dephosphorylation of NF-AT(p) in cell extracts is inhibited by prior treatment of T cells with the immunosuppressive drugs cyclosporin A or FK506, which inhibit the phosphatase activity of calcineurin when complexed with their specific binding proteins, cyclophilin and FK506-binding protein. This work identifies NF-AT(p) as a DNA-binding phosphoprotein and a target for the drug/immunophilin/calcineurin complexes thought to mediate the inhibition of interleukin-2 gene induction by cyclosporin A and FK506.

    Original languageEnglish (US)
    Pages (from-to)3747-3752
    Number of pages6
    JournalJournal of Biological Chemistry
    Volume268
    Issue number5
    StatePublished - 1993

    ASJC Scopus subject areas

    • Biochemistry
    • Molecular Biology
    • Cell Biology

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  • Cite this

    McCaffrey, P. G., Perrino, B. A., Soderling, T. R., & Rao, A. (1993). NF-AT(p), a T lymphocyte DNA-binding protein that is a target for calcineurin and immunosuppressive drugs. Journal of Biological Chemistry, 268(5), 3747-3752.