title: Comparative analysis of calcineurin inhibition by complexes of immunosuppressive drugs with human FK506 binding proteins.
abstract: Multiple intracellular receptors of the FK506 binding protein (FKBP) family of peptidylprolyl cis/trans-isomerases are potential targets for the immunosuppressive drug FK506. Inhibition of the protein phosphatase calcineurin (CaN), which has been implicated in the FK506-mediated blockade of T cell proliferation, was shown to involve a gain of function in the FKBP12/FK506 complex. We studied the potential of six human FKBPs to contribute to CaN inhibition by comparative examination of inhibition constants of the respective FK506/FKBP complexes. Interestingly, these FKBPs form tight complexes with FK506, exhibiting comparable dissociation constants, but the resulting FK506/FKBP complexes differ greatly in their affinity for CaN, with IC50 values in the range of 0.047-17 microM. The different capacities of FK506/FKBP complexes to affect CaN activity are partially caused by substitutions corresponding to the amino acid side chains K34 and I90 of FKBP12. Only the FK506 complexes of FKBP12, FKBP12.6, and FKBP51 showed high affinity to CaN; small interfering RNA against these FKBP allowed defining the contribution of individual FKBP in an NFAT reporter gene assay. Our results allow quantitative correlation between FK506-mediated CaN effects and the abundance of the different FKBPs in the cell.
authors.affiliation: Max Planck Research Unit for Enzymology of Protein Folding, Weinbergweg 22, D-06120 Halle/Saale, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Weiwad
authors.forename: Frank
authors.initials: F
authors.lastname: Edlich
authors.forename: Susann
authors.initials: S
authors.lastname: Kilka
authors.forename: Frank
authors.initials: F
authors.lastname: Erdmann
authors.forename: Franziska
authors.initials: F
authors.lastname: Jarczowski
authors.forename: Madlen
authors.initials: M
authors.lastname: Dorn
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Moutty
authors.forename: Gunter
authors.initials: G
authors.lastname: Fischer
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019703:Calcineurin / Q000378:metabolism; D065095:Calcineurin Inhibitors; D002147:Calmodulin / Q000502:physiology; D002417:Cattle; D004791:Enzyme Inhibitors / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D007166:Immunosuppressive Agents / Q000378:metabolism / Q000494:pharmacology*; D019169:Jurkat Cells; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000378:metabolism* / Q000502:physiology; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D020123:Sirolimus / Q000378:metabolism / Q000494:pharmacology; D013379:Substrate Specificity; D016559:Tacrolimus / Q000378:metabolism / Q000494:pharmacology; D022061:Tacrolimus Binding Protein 1A / Q000502:physiology; D022021:Tacrolimus Binding Proteins / Q000378:metabolism / Q000502:physiology*; D000099159:Tacrolimus Binding Protein 5
chemical_list: D019703:Calcineurin; D065095:Calcineurin Inhibitors; D002147:Calmodulin; D004791:Enzyme Inhibitors; D007166:Immunosuppressive Agents; D009097:Multienzyme Complexes; D020123:Sirolimus; D016559:Tacrolimus; D022061:Tacrolimus Binding Protein 1A; D022021:Tacrolimus Binding Proteins; D000099159:Tacrolimus Binding Protein 5; C403484:tacrolimus binding protein 1B