Abstract

The androgen receptor (AR) is the main driver ofprostate cancer (PC) development and progression,and the primary therapeutic target in PC. To date,two functional ubiquitination sites have been iden-tified on AR, both located in its C-terminal ligandbinding domain (LBD). Recent reports highlight theemergence of AR splice variants lacking the LBD thatcan arise during disease progression and contributeto castrate resistance. Here, we report a novel N-terminal ubiquitination site at lysine 311. Ubiquitina-tion of this site plays a role in AR stability and is crit-ical for its transcriptional activity. Inactivation of thissite causes AR to accumulate on chromatin and inac-tivates its transcriptional function as a consequenceof inability to bind to p300. Additionally, mutation atlysine 311 affects cellular transcriptome altering theexpression of genes involved in chromatin organiza-tion, signaling, adhesion, motility, development andmetabolism. Even though this site is present in clini-cally relevant AR-variants it can only be ubiquitinatedin cells when AR retains LBD suggesting a role for ARC-terminus in E2/E3 substrate recognition. We reportthat as a consequence AR variants lacking the LBDcannot be ubiquitinated in the cellular environmentand their protein turnover must be regulated via analternate pathway.