Nuclear factor of activated T cells (NFAT) leads to the transcription of diverse inducible genes involved in many biological processes; therefore, aberrant NFAT expression is responsible for the development and exacerbation of various disorders. Since five isoforms of NFAT (NFATc1-c4, NFAT5) exhibit distinct and overlapping functions, selective control of a part, but not all, of NFAT family members is desirable.By comparing the binding activity of each NFATc1-c4 with its regulatory enzyme, calcineurin (CN), using a quantitative immunoprecipitation assay, we found a new CN-binding region (CNBR) selectively functioning in NFATc1 and NFATc4. This region, termed CNBR3, is located between two preexisting CNBR1 and CNBR2, within the Ca 2+ regulatory domain. The nuclear translocation of NFATc1 but not NFATc2 in T cells was suppressed by ectopic expression of CNBR3 and, accordingly, NFATc1-dependent cytokine expression was downregulated. Through competition assays using NFATc1-derived partial peptides and mass spectrometry with photoaffinity technology, we identified 18 amino acids in NFATc1 (Arg 258 to Pro 275 ) and 13 amino acids in CN catalytic subunit (CNA) (Asn 77 to Gly 89 ) responsible for CNA/CNBR3 binding in which Cys 263 and Asp 82 , respectively, played crucial roles.The possible selective regulation of NFAT-mediated biological processes by targeting this new CN/NFAT-binding region is suggested.
K E Y W O R D Scalcineurin-binding region, cytokine, immunosuppressant, nuclear translocation 3198 | KITAMURA eT Al.