title: InterAKTions with FKBPs--mutational and pharmacological exploration.
abstract: The FK506-binding protein 51 (FKBP51) is an Hsp90-associated co-chaperone which regulates steroid receptors and kinases. In pancreatic cancer cell lines, FKBP51 was shown to recruit the phosphatase PHLPP to facilitate dephosphorylation of the kinase Akt, which was associated with reduced chemoresistance. Here we show that in addition to FKBP51 several other members of the FKBP family bind directly to Akt. FKBP51 can also form complexes with other AGC kinases and mapping studies revealed that FKBP51 interacts with Akt via multiple domains independent of their activation or phosphorylation status. The FKBP51-Akt1 interaction was not affected by FK506 analogs or Akt active site inhibitors, but was abolished by the allosteric Akt inhibitor VIII. None of the FKBP51 inhibitors affected AktS473 phosphorylation or downstream targets of Akt. In summary, we show that FKBP51 binds to Akt directly as well as via Hsp90. The FKBP51-Akt interaction is sensitive to the conformation of Akt1, but does not depend on the FK506-binding pocket of FKBP51. Therefore, FKBP inhibitors are unlikely to inhibit the Akt-FKBP-PHLPP network.
authors.affiliation: Research Group Chemical Genomics, Max Planck Institute of Psychiatry, Munich, Germany.
authors.forename: Anne-Katrin
authors.initials: AK
authors.lastname: Fabian
authors.forename: Andreas
authors.initials: A
authors.lastname: März
authors.forename: Sonja
authors.initials: S
authors.lastname: Neimanis
authors.forename: Ricardo M
authors.initials: RM
authors.lastname: Biondi
authors.forename: Christian
authors.initials: C
authors.lastname: Kozany
authors.forename: Felix
authors.initials: F
authors.lastname: Hausch
mesh_terms: D000495:Allosteric Site; D009154:Mutation; D010766:Phosphorylation; D011485:Protein Binding; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D022021:Tacrolimus Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D051057:Proto-Oncogene Proteins c-akt; D022021:Tacrolimus Binding Proteins