Ligand induced dissociation of the AR homodimer precedes AR monomer translocation to the nucleus

Abstract

The androgen receptor (AR) regulates male sexual development. We have now investigated AR homodimerization, hormone-dependent monomerization and nuclear translocation in PC-3 and COS-1 cells, by utilizing mutations associated with the androgen insensitivity syndrome: Pro767Ala, Phe765Leu, Met743Val and Trp742Arg. AR wild type (WT) was expressed as a homodimer in the cytoplasm, while none of these mutants formed homodimers. Unlike AR WT which responded to 1 nM dihydrotestosterone (DHT) to dissociate and translocate into the nucleus, AR Pro767Ala and Phe765Leu mutants remain as the monomer in the cytoplasm. In the crystal structure of the AR LBD homodimer, Pro767 and Phe765 reside closely on a loop that constitutes the dimer interface; their sidechains interact with the Pro767 of the other monomer and with the DHT molecule in the ligand-binding pocket. These observations place Phe765 at a position to facilitate DHT binding to Pro767 and lead to dissociation of the AR homodimer in the cytoplasm. This Pro-Phe Met relay may constitute a structural switch that mediates androgen signaling and is conserved in other steroid hormone receptors.

FKBP51 and FKBP52 regulate androgen receptor dimerization and proliferation in prostate cancer cells

“…monomers even in the presence of DHT [20]. Consistent with the previous study, we found that the dimerization of AR-P767A mutant was substantially attenuated compared with that of wild-type AR.…”

“…A reduction in AR dimerization in cells treated with the FKBP51 PPIase inhibitor suggests that FKBP51 may isomerize proline in AR. It was reported that AR Pro 767 mutated to Ala remains a monomer, even in the presence of DHT [20]. We confirmed that the AR P767A mutant was defective in dimer formation compared to wild-type AR (Fig.…”

Combined FCS and PCH Analysis to Quantify Protein Dimerization in Living Cells

“…Classic examples are the dimerization and activation of protein kinases like extracellular signal-regulated kinase 2 (ERK2) and rapidly accelerated fibrosarcoma (RAF) [ 1 , 2 , 3 ]. Most nuclear receptors are monomeric in the cytosol and become dimeric and active upon the binding of ligand molecules [ 4 , 5 ], although, for the human androgen receptor, this may be the other way around [ 6 ]. Unraveling the dimerization mechanism of the androgen receptor is important because it has been implicated in hormone-related diseases [ 7 ].…”

Novel missense mutation in ligand binding domain of AR gene identified in patient with androgen insensitivity syndrome from Ukraine

“…Binding of androgens to AR leads to a conformational change, allowing the transfer of the receptor from the cytoplasm to the nucleus, where it functions as a homodimer. 4 Then, AR binds to a specific DNA sequence known as androgen response element (ARE) and interacts with other proteins in the nucleus to modulate transcriptional regulation. 5 It was shown that androgen receptor undergoes phosphorylation, the patterns of which change after ligand binding.…”

“…The main function of the androgen receptor is the direct regulation of transcription. Binding of androgens to AR leads to a conformational change, allowing the transfer of the receptor from the cytoplasm to the nucleus, where it functions as a homodimer 4 . Then, AR binds to a specific DNA sequence known as androgen response element (ARE) and interacts with other proteins in the nucleus to modulate transcriptional regulation 5 .…”