Based on our recent findings on androgen receptor (AR) phosphorylation at serine 81 and AR interactions with protein phosphatase 1 (PP1), we are updating Aims 4 and 5 (ROO phase) fronri the parental grant. These two Aims will be integrated into Aim 5 of the updated proposal for the ROO phase, and a new Aim 4 will build on our recent findings made during the K99 phase examining AR serine 81 phosphorylation and AR association with chromatin.
Aim 4. Characterize the higher molecular weight AR molecules that associate with AR chromatin binding and serine 81 phosphorylation. Our data suggest that serine 81 phosphorylation may target AR for further posttranslational modifications (such as monoubiquitylation or SUMO conjugation) that may be required for stable chromatin binding and transcriptional activation. Biochemical and molecular approaches will be used to test these hypotheses.
Aim 5. Determine the functional importance of AR phosphorylation/ dephosphorylation and its interaction with PP1beta. Our initial Aims 4 and 5 proposed to study the interactions between AR and PP1. The PP1 catalytic subunit has 3 isoforms, alpha, beta, and gamma, and our recent data indicate that PP1beta has the greatest interaction. Therefore, the experiments have been modified to focus on regulation of AR functions by PP1beta.
|Gao, Shuai; Ye, Huihui; Gerrin, Sean et al. (2016) ErbB2 Signaling Increases Androgen Receptor Expression in Abiraterone-Resistant Prostate Cancer. Clin Cancer Res 22:3672-82|
|Liu, Xiaming; Han, Weiwei; Gulla, Sarah et al. (2016) Protein phosphatase 1 suppresses androgen receptor ubiquitylation and degradation. Oncotarget 7:1754-64|
|Liu, Xiaming; Han, Weiwei; Gulla, Sarah et al. (2016) Androgen ablation elicits PP1-dependence for AR stabilization and transactivation in prostate cancer. Prostate 76:649-61|
|Gao, Shuai; Gao, Yanfei; He, Housheng Hansen et al. (2016) Androgen Receptor Tumor Suppressor Function Is Mediated by Recruitment of Retinoblastoma Protein. Cell Rep 17:966-976|
|Sowalsky, Adam G; Xia, Zheng; Wang, Liguo et al. (2015) Whole transcriptome sequencing reveals extensive unspliced mRNA in metastatic castration-resistant prostate cancer. Mol Cancer Res 13:98-106|
|Chen, Shaoyong; Gulla, Sarah; Cai, Changmeng et al. (2012) Androgen receptor serine 81 phosphorylation mediates chromatin binding and transcriptional activation. J Biol Chem 287:8571-83|
|Cai, Changmeng; He, Housheng Hansen; Chen, Sen et al. (2011) Androgen receptor gene expression in prostate cancer is directly suppressed by the androgen receptor through recruitment of lysine-specific demethylase 1. Cancer Cell 20:457-71|