Androgen receptor acetylation sites differentially regulate gene control

Androgen receptor (AR) function is modulated by post-translational modifications such as acetylation, ubiquitylation, sumoylation, and phosphorylation. Concerning acetylation, three lysines residues located in a consensus KxKK motif of the AR hinge domain have been identified. For a better evaluation of the role of this modification, the activity of AR modified at different acetylation sites was determined by comparing the effects on natural and synthetic promoters. We found that mutation of AR acetylation sites affected both potency and efficacy of androgen-dependent response. Remarkably, elimination of all three acetylation sites was still compatible with strong AR activity on the PSA and MMTV promoters, but not on the Pem promoter. This differential effect was seen at various wild-type (wt) to mutant AR receptor ratios and at changing hormone concentrations. Subcellular localization studies showed that both mutated and wt AR efficiently translocated into the cell nucleus. Plasmid immunoprecipitation revealed comparable binding of both receptor forms to the Pem promoter. The differential effects observed for the Pem promoter were partially due to an androgen response element (ARE) named ARE-1 which was only poorly stimulated by the AR acetylation site mutant. Finally, AR mutants impaired in their N/C interaction elicited intact stimulation of the Pem promoter, suggesting that AR acetylation was not influenced by this inter-domain communication. The promoter-selective effects seen for the AR acetylation site mutants strongly suggest this post-translational modification to be important in the fine-tuning of the effects of androgens on different target genes.