LNCaP prostate cancer cell lines overexpressing wild-type or GARRPR-mutant Bag-1L

The BF-3 pocket of the androgen receptor (AR) has been identified as an allosteric modulator of the transactivation function of the AR. We now demonstrate that a duplicated GARRPR motif at the N-terminus of the cochaperone Bag-1L functions through this BF-3 domain. Amino acid exchanges in these two motifs impair binding of Bag-1L to the AR but increase the androgen-dependent activation of a subset of AR-target genes. We have therefore identified GARRPR as a novel BF-3 regulatory sequence important for fine-tuning the activity of the receptor. LNCaP cells stably expressing the empty vector construct (=control), or wild-type or N-terminal GARRPR mutant Bag-1L were cultured under hormone-starvation conditions for 72 h and then treated with vehicle or 10 nM DHT for 4 h. Biological triplicate samples were analyzed for each cell line.