Activation of nuclear factor of activated T cells in a cyclosporin A-resistant pathway.
The mechanism of action of the immunosuppressive drug cyclosporin A (CsA) is the inactivation of the Ca2+/calmodulin-dependent serine-threonine phosphatase calcineurin by the drug-immunophilin complex. Inactive calcineurin is unable to activate the nuclear factor of activated T cells (NFAT), a transcription factor required for expression of the interleukin 2 (IL-2) gene. IL-2 production by CsA-treated cells is therefore dramatically reduced. We demonstrate here, however, that NFAT can be activated, and significant levels of IL-2 can be produced by the CsA-resistant CD28-signaling pathway. In transient transfection assays, both multicopy NFAT- and IL-2 promoter-beta-galactosidase reporter gene constructs could be activated by phorbol 12-myristate 13-acetate (PMA)/alpha-CD28 stimulation, and this activation was resistant to CsA. Electrophoretic mobility shift assay showed the induction of a CsA-resistant NFAT complex in the nuclear extracts of peripheral blood T cells stimulated with PMA plus alphaCD28. Peripheral blood T cells stimulated with PMA/alphaCD28 produced IL-2 in the presence of CsA. Collectively, these data suggest that NFAT can be activated and IL-2 can be produced in a calcineurin independent manner.
Ghosh
P
P
Laboratory of Experimental Immunology, Division of Basic Science, SAIC, Frederick, Maryland 21702-1201, USA.
Sica
A
A
Cippitelli
M
M
Subleski
J
J
Lahesmaa
R
R
Young
H A
HA
Rice
N R
NR
D001483:Base Sequence; D002478:Cells, Cultured; D016572:Cyclosporine / Q000494:pharmacology*; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000378:metabolism; D004351:Drug Resistance; D006801:Humans; D007376:Interleukin-2 / Q000096:biosynthesis / Q000235:genetics; D008969:Molecular Sequence Data; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000378:metabolism; D009838:Oligodeoxyribonucleotides; D010957:Plasmids; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D014157:Transcription Factors / Q000096:biosynthesis* / Q000378:metabolism
D004268:DNA-Binding Proteins; D007376:Interleukin-2; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D009838:Oligodeoxyribonucleotides; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D016572:Cyclosporine