Differential Impact of Tetratricopeptide Repeat Proteins on the Steroid Hormone Receptors

Abstract

BackgroundTetratricopeptide repeat (TPR) motif containing co-chaperones of the chaperone Hsp90 are considered control modules that govern activity and specificity of this central folding platform. Steroid receptors are paradigm clients of Hsp90. The influence of some TPR proteins on selected receptors has been described, but a comprehensive analysis of the effects of TPR proteins on all steroid receptors has not been accomplished yet.Methodology and Principal FindingsWe compared the influence of the TPR proteins FK506 binding proteins 51 and 52, protein phosphatase-5, C-terminus of Hsp70 interacting protein, cyclophillin 40, hepatitis-virus-B X-associated protein-2, and tetratricopeptide repeat protein-2 on all six steroid hormone receptors in a homogeneous mammalian cell system. To be able to assess each cofactor's effect on the transcriptional activity of on each steroid receptor we employed transient transfection in a reporter gene assay. In addition, we evaluated the interactions of the TPR proteins with the receptors and components of the Hsp90 chaperone heterocomplex by coimmunoprecipitation. In the functional assays, corticosteroid and progesterone receptors displayed the most sensitive and distinct reaction to the TPR proteins. Androgen receptor's activity was moderately impaired by most cofactors, whereas the Estrogen receptors' activity was impaired by most cofactors only to a minor degree. Second, interaction studies revealed that the strongly receptor-interacting co-chaperones were all among the inhibitory proteins. Intriguingly, the TPR-proteins also differentially co-precipitated the heterochaperone complex components Hsp90, Hsp70, and p23, pointing to differences in their modes of action.Conclusion and SignificanceThe results of this comprehensive study provide important insight into chaperoning of diverse client proteins via the combinatorial action of (co)-chaperones. The differential effects of the TPR proteins on steroid receptors bear on all physiological processes related to steroid hormone activity.

Accelerated neurodegeneration through chaperone-mediated oligomerization of tau

“…FKBP51 is a profolding Hsp90 cochaperone that forms a complex with Hsp90 via the tetratricopeptide (TPR) domain (25,26), a region also found on other Hsp90 cochaperones, including the carboxyl terminus of Hsp70-interacting protein (CHIP; also known as STUB1) and FK506 binding protein 52 (FKBP52; also known as FKBP4) (27,28). However, the TPR cochaperone with the highest affinity for Hsp90 is FKBP51 (29). Here we investigate how the FKBP51/ Hsp90 complex prevents clearance of tau, the impact it has on tau pathogenesis, and whether it plays a role in disease onset due to age-associated changes in TPR protein levels in the human brain.…”

The activity of the glucocorticoid receptor is regulated by SUMO conjugation to FKBP51

“…32 Upon hormone stimulation, there is a switch from FKBP51 to the closely related TPR protein, FKBP52, which positively regulates GR activity. 5,7,8 Therefore, we analyzed whether impairment of SUMO conjugation to FKBP51 alters the cochaperone composition of this complex.…”

“…5,32 Therefore, the fact that impairment of FKBP51 SUMOylation prevents both FKBP51 binding to Hsp90 and its inhibitory effect on GR activity while promotes FKBP52 recruitment and GR nuclear translocation provides a mechanistic explanation, suggesting that SUMO conjugation to FKBP51 underlies its preferential recruitment to the GR chaperone complex, which in turn determines the final outcome of GR signaling. Interestingly, we found through in silico analysis that FKBP52 has SUMO conjugation consensus and non-consensus sites.…”

“…The following plasmids used in this work were previously described, as indicated: FLAG-FKBP51 and FLAG-FKBP52; 5 GSTUbc9; 47 HA-GR and the GR reporter plasmid pΔ(TAT) 4 -Luc (TAT4-luc); 18 the NF-κB reporter plasmid (κB-luc); 48 and FLAG-Hsp90 and the Gaussia luciferase reporter plasmid. 32 The pHC-RED1-C1 plasmid was obtained from Clontech (Mountain View, CA, USA). The following plasmids were kindly provided: HA-SUMO2, V5-Ubc9, and 6 × His-SUMO1, SUMO2 and SUMO3 by Dr. R Hay; 49-51 YFP-GR by Dr. JA Cidlowski; 52 FLAG-SENP1 by Dr. E Yeh; 53 PIAS4 expression vector by Dr. JA Iñiguez-Lluhí; 54 PIAS4 and control shRNA by Dr. MJ Hendzel; 55 the GR reporter plasmid MMTV-luc by Dr. R Evans; 56 p65 expression vector by Dr. M Karin; the β-galactosidase reporter plasmid by Dr. D Spengler; 57 GST-Hsp90 by Dr. K Nagata; 58 pGEX-PIAS4 by Dr. SP Goff.…”

“…FKBP51 − / − MEF cells were electroporated with TAT4-luc together with GR expression vector and the indicated plasmids and stimulated 24 h later as indicated. Firefly luciferase and Gaussia luciferase activities were determined as described in Schulke et al 32 Luciferase activity was relativized to β-galactosidase or Gaussia luciferase activity.…”