Agonist-specific Protein Interactomes of Glucocorticoid and Androgen Receptor as Revealed by Proximity Mapping

Abstract

Glucocorticoid receptor (GR) and androgen receptor (AR) are steroid-inducible transcription factors (TFs). The GR and the AR are central regulators of various metabolic, homeostatic and differentiation processes and hence important therapeutic targets, especially in inflammation and prostate cancer, respectively. Hormone binding to these steroid receptors (SRs) leads to DNA binding and activation or repression of their target genes with the aid of interacting proteins, coregulators. However, protein interactomes of these important drug targets have remained poorly defined. We used proximity-dependent biotin identification to map the protein interaction landscapes of GR and AR in the presence and absence of their cognate agonist (dexamethasone, 5α-dihydrotestosterone) and antagonist (RU486, enzalutamide) in intact human cells. We reproducibly identified more than 30 proteins that interacted with the GR in an agonist-specific manner and whose interactions were significantly influenced by the DNA-binding function of the receptor. Interestingly, the agonist-dependent interactome of the GR overlapped considerably with that of the AR. In addition to known coactivators, corepressors and components of BAF (SWI/SNF) chromatin-remodeling complex, we identified a number of proteins, including lysine methyltransferases and demethylases that have not been previously linked to glucocorticoid or androgen signaling. A substantial number of these novel agonist-dependent GR/AR-interacting proteins, BCOR, IRF2BP2, RCOR1, and TLE3, have previously been implicated in transcription repression. This together with our data on the effect of BCOR, IRF2BP2, and RCOR1 on GR target gene expression suggests multifaceted functions and roles for SR coregulators. These first high confidence SR interactomes will aid in therapeutic targeting of the GR and the AR.

The Glucocorticoid Receptor Is a Key Player for Prostate Cancer Cell Survival and a Target for Improved Antiandrogen Therapy

“…Therefore, it was proposed that GR can functionally replace the AR, when AR signaling is blocked. Consistently, it has been shown that both receptors not only exhibit a significant overlap in their transcriptome (18), but also share several interacting proteins (21). In line with these observations, stimulation of GR activity could rescue cells from enzalutamide-induced cell death (18).…”

TNF-α inhibits glucocorticoid receptor-induced gene expression by reshaping the GR nuclear cofactor profile

“…In this technique, a biotin ligase, BirA, was fused to the N-terminal part of GR, and the gene was stably integrated in the cells and expressed at physiological levels, enabling BirA biotinylation of proteins based on their proximity (30). This strategy has recently been shown to be particularly amenable for nuclear receptors such as the GR and androgen receptor (31).…”

Non-canonical dimerization of the androgen receptor and other nuclear receptors: implications for human disease

“…In this manner, occupancy of the LBP by ligands regulates the dynamics and stability of surfaces that recognize coregulators and is thus allosterically coupled to the recruitment of these proteins to the AR (Estébanez-Perpiñá et al 2005, Estebanez-Perpina et al 2007. Albeit a recent proteomics study has identified the essentially overlapping, agonist-specific interactomes of both AR and GR (Lempiäinen et al 2017), the detailed molecular determinants of NR binding to a large number of coregulators are far from being well understood.…”

“…These NR coregulators underlie the tissue-selective actions of NR ligands and are also emerging therapeutic targets per se, although they have proved hard to target so far (Yi et al 2015, Wang et al 2016, Ruggero et al 2018. All NR domains have been involved in coregulator recruitment and macromolecular complex formation, although the atomic details still remain elusive (Dasgupta et al 2014, Foley & Mitsiades 2016, Giudici et al 2016, Lempiäinen et al 2017.…”