TY  - JOUR
A1  - Kilu, Whitney
A1  - Merk, Daniel
A1  - Steinhilber, Dieter
A1  - Proschak, Ewgenij
A1  - Heering, Jan Peter
T1  - Heterodimer formation with retinoic acid receptor RXRα modulates coactivator recruitment by peroxisome proliferator-activated receptor PPARγ
T2  - The journal of biological chemistry
N2  - Nuclear receptors (NRs) activate transcription of target genes in response to binding of ligands to their ligand-binding domains (LBDs). Typically, in vitro assays use either gene expression or the recruitment of coactivators to the isolated LBD of the NR of interest to measure NR activation. However, this approach ignores that NRs function as homo- as well as heterodimers and that the LBD harbors the main dimerization interface. Cofactor recruitment is thereby interconnected with oligomerization status as well as ligand occupation of the partnering LBD through allosteric cross talk. Here we present a modular set of homogeneous time-resolved FRET–based assays through which we investigated the activation of PPARγ in response to ligands and the formation of heterodimers with its obligatory partner RXRα. We introduced mutations into the RXRα LBD that prevent coactivator binding but do not interfere with LBD dimerization or ligand binding. This enabled us to specifically detect PPARγ coactivator recruitment to PPARγ:RXRα heterodimers. We found that the RXRα agonist SR11237 destabilized the RXRα homodimer but promoted formation of the PPARγ:RXRα heterodimer, while being inactive on PPARγ itself. Of interest, incorporation of PPARγ into the heterodimer resulted in a substantial gain in affinity for coactivator CBP-1, even in the absence of ligands. Consequently, SR11237 indirectly promoted coactivator binding to PPARγ by shifting the oligomerization preference of RXRα toward PPARγ:RXRα heterodimer formation. These results emphasize that investigation of ligand-dependent NR activation should take NR dimerization into account. We envision these assays as the necessary assay tool kit for investigating NRs that partner with RXRα.
KW  - PPARγ
KW  - RXRα
KW  - heterodimer
KW  - homodimer
KW  - homogeneous time-resolved FRET (HTRF)
KW  - cofactor recruitment
KW  - allostery
KW  - drug target
Y1  - 2021
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/62818
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-628186
SN  - 1083-351X
SN  - 0021-9258
N1  - This work was supported by the Landes-Offensive zur Entwicklung Wissenschaftlich oekonomischer Exzellenz (LOEWE) of the State of Hessen, and Research Center for Translational Medicine and Pharmacology TMP.
VL  - 297
IS  - 1, art. 100814
SP  - 1
EP  - 16
PB  - ASBMB Publications
CY  - Bethesda, Md.
ER  -