A Genomic Approach to Assessing the Fkbp52-Regulated Androgen Receptor Cistrome and Transcriptome
Androgen receptor (AR)-regulated genes contribute to the initiation and progression of prostate cancer. Receptor signaling persists and plays a pivotal role in late-stages of the disease, for which there is currently no treatment. Thus, there is a need to understand the mechanisms regulating AR function as a means to identify drug targets for potential therapeutics. The FKBP52 cochaperone has emerged in recent years as a regulator of AR activity that is functionally linked in the AR signaling pathway. FKBP52 is a known positive regulator of AR and believed to interact with AR at its binding function 3 surface (BF3), a site located on AR’s hormone binding domain. We previously demonstrated that FKBP52 and an AR co-activator, β-catenin, interact directly in vitro and act in concert to promote up-regulation of both hormone-independent and dependent AR signaling. Here, we have demonstrated the amino acids on each protein necessary to regulate AR activity in vitro- FKBP52 relies on the proline-rich loop situated above its catalytic pocket while β-catenin requires key amino acids found in its armadillo repeat domain. We also show that Bag-1L, a cochaperone which binds AR BF3 and aids in AR folding and maturation, interacts directly with β-catenin, suggesting multiple distinct complexes involving β-catenin may regulate AR activity. Using the CRISPR/Cas9 system, we knocked out FKBP52 from 22Rv1 cells and found that these cells require higher hormone concentrations for receptor induction and they fail to form tumors in mouse xenografts. ChIP-seq and RNA-seq of these cells revealed marked differences in AR DNA binding sites as well as distinct changes in gene expression, signifying FKBP52 influences AR activity significantly more than was previously known. FKBP52 was validated as a possible therapeutic target through the use of small molecules directed against the cochaperone, resulting in the inhibition of FKBP52-specific AR activity.
Ortiz, Nina Raquelle, "A Genomic Approach to Assessing the Fkbp52-Regulated Androgen Receptor Cistrome and Transcriptome" (2021). ETD Collection for University of Texas, El Paso. AAI28419443.