title: Identification of calcineurin as a key signalling enzyme in T-lymphocyte activation.
abstract: The immunosuppressive drugs cyclosporin A (CsA) and FK506 both interfere with a Ca(2+)-sensitive T-cell signal transduction pathway, thereby preventing the activation of specific transcription factors (such as NF-AT and NF-IL2A) involved in lymphokine gene expression. CsA and FK506 seem to act by interaction with their cognate intracellular receptors, cyclophilin and FKBP, respectively (see ref. 11 for review). The Ca2+/calmodulin-regulated phosphatase calcineurin is a major target of drug-isomerase complexes in vitro. We have therefore tested the hypothesis that this interaction is responsible for the in vivo effects of CsA/FK506. We report here that overexpression of calcineurin in Jurkat cells renders them more resistant to the effects of CsA and FK506 and augments both NFAT- and NFIL2A-dependent transcription. These results identify calcineurin as a key enzyme in the T-cell signal transduction cascade and provide biological evidence to support the notion that the interaction of drug-isomerase complexes with calcineurin underlies the molecular basis of CsA/FK506-mediated immunosuppression.
authors.affiliation: Beckman Center for Molecular and Genetic Medicine, Howard Hughes Medical Institute, Stanford University School of Medicine, California 94305.
authors.forename: N A
authors.initials: NA
authors.lastname: Clipstone
authors.forename: G R
authors.initials: GR
authors.lastname: Crabtree
mesh_terms: D000818:Animals; D019703:Calcineurin; D002148:Calmodulin-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism; D002460:Cell Line; D016572:Cyclosporine / Q000494:pharmacology; D015870:Gene Expression; D006801:Humans; D007376:Interleukin-2 / Q000235:genetics; D008213:Lymphocyte Activation; D051379:Mice; D008954:Models, Biological; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000187:drug effects; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology*; D016559:Tacrolimus / Q000378:metabolism / Q000494:pharmacology; D022021:Tacrolimus Binding Proteins; D014162:Transfection
chemical_list: D002148:Calmodulin-Binding Proteins; D002352:Carrier Proteins; D007376:Interleukin-2; D011948:Receptors, Antigen, T-Cell; D011994:Recombinant Proteins; D016572:Cyclosporine; D019703:Calcineurin; D010749:Phosphoprotein Phosphatases; D022021:Tacrolimus Binding Proteins; D016559:Tacrolimus