Dynamic phase separation of the androgen receptor and its coactivators key to regulate gene expression
Fan Zhang, M. Biswas, Shabnam Massah, Joseph Lee, Shreyas Lingadahalli, Samantha Wong, C A Wells, Jane Foo, Nabeel Khan, Hélène Morin, Neetu Saxena, Sonia H.Y. Kung, Bei Sun, Ana Karla Parra Nuñez, C. Antonio Sánchez, Novia Chan, Lauren Ung, Umut Berkay Altıntaş, Jennifer M. Bui, Yuzhuo Wang, Ladan Fazli, Htoo Zarni Oo, Paul S. Rennie, Nathan A. Lack, Artem Cherkasov, Martin Gleave, Jörg Gsponer, Nada Lallous
Abstract
Numerous cancers, including prostate cancer (PCa), are addicted to transcription programs driven by specific genomic regions known as super-enhancers (SEs). The robust transcription of genes at such SEs is enabled by the formation of phase-separated condensates by transcription factors and coactivators with intrinsically disordered regions. The androgen receptor (AR), the main oncogenic driver in PCa, contains large disordered regions and is co-recruited with the transcriptional coactivator mediator complex subunit 1 (MED1) to SEs in androgen-dependent PCa cells, thereby promoting oncogenic transcriptional programs. In this work, we reveal that full-length AR forms foci with liquid-like properties in different PCa models. We demonstrate that foci formation correlates with AR transcriptional activity, as this activity can be modulated by changing cellular foci content chemically or by silencing MED1. AR ability to phase separate was also validated in vitro by using recombinant full-length AR protein. We also demonstrate that AR antagonists, which suppress transcriptional activity by targeting key regions for homotypic or heterotypic interactions of this receptor, hinder foci formation in PCa cells and phase separation in vitro. Our results suggest that enhanced compartmentalization of AR and coactivators may play an important role in the activation of oncogenic transcription programs in androgen-dependent PCa.