The FKBP52 Domain Requirements for FKBP52/β-Catenin Co-Regulation of AR Activity.

<p>(A-C) Wild type AR, the AR-inducible luciferase reporter plasmid, and the constitutively active β-galactosidase reporter plasmid were cotransfected simultaneously with each of the plasmids indicated for the different treatment groups in 52KO MEF cells. Cells were induced with 10 pM DHT or ethanol. Following cell lysis, AR expression was tested through a luciferase assay, followed by normalization to β-galactosidase activity. In all graphs, statistically significant differences as compared to the vector alone control for each hormone condition are denoted by asterisks (*p < 0.05; ***p < 0.001). (A) The assay was performed in the presence or absence of FKBP52, β-catenin (S33A), and the PPIase-deficient FKBP52 mutant FKBP52 (F130Y). The PPIase-deficient FKBP52 mutant retains the ability to synergize with β-catenin (S33A) indicating that PPIase enzymatic activity is not critical for synergy. (B) The assay was performed in the presence or absence of β-catenin (S33A), FKBP52, and the Hsp90 binding-deficient mutant FKBP52 (K354A). FKBP52 binding to Hsp90 is not required for the synergistic upregulation of AR activity by FKBP52 and β-catenin. C. The assay was performed in the presence or absence of β-catenin (S33A), FKBP52, FKBP51, and the FKBP51 (A116V/L119P) mutant. The FKBP51 gain of function mutant exhibits substantial synergism with β-catenin indicating that the FK1 domain and the proline-rich loop are important for synergy.