@article{qiu_sakato_sacho_wilkins_zhang_modrichd_hingorani_erie_weninger_2015, title={MutL traps MutS at a DNA mismatch}, volume={112}, ISSN={["0027-8424"]}, DOI={10.1073/pnas.1505655112}, abstractNote={Significance}, number={35}, journal={PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, author={Qiu, Ruoyi and Sakato, Miho and Sacho, Elizabeth J. and Wilkins, Hunter and Zhang, Xingdong and Modrichd, Paul and Hingorani, Manju M. and Erie, Dorothy A. and Weninger, Keith R.}, year={2015}, month={Sep}, pages={10914–10919} }
 @article{he_chen_mooney_rajagopalan_bhargava_sacho_keith_bryan_kulkarni_orban_et al._2015, title={Phosphorylation-induced Conformational Ensemble Switching in an Intrinsically Disordered Cancer/Testis Antigen}, volume={290}, ISSN={["1083-351X"]}, DOI={10.1074/jbc.m115.658583}, abstractNote={Background: PAGE4, an intrinsically disordered protein up-regulated in prostate cancer, binds to c-Jun and potentiates its transactivation. Results: The effects of phosphorylation on PAGE4 conformation, dynamics, and c-Jun binding were determined by NMR. Conclusion: Phosphorylation induces a more compact conformational ensemble, restricting access to the c-Jun binding site. Significance: This study may help to explain how phosphorylation of PAGE4 alters its binding to c-Jun. Prostate-associated gene 4 (PAGE4) is an intrinsically disordered cancer/testis antigen that is up-regulated in the fetal and diseased human prostate. Knocking down PAGE4 expression results in cell death, whereas its overexpression leads to a growth advantage of prostate cancer cells (Zeng, Y., He, Y., Yang, F., Mooney, S. M., Getzenberg, R. H., Orban, J., and Kulkarni, P. (2011) The cancer/testis antigen prostate-associated gene 4 (PAGE4) is a highly intrinsically disordered protein. J. Biol. Chem. 286, 13985–13994). Phosphorylation of PAGE4 at Thr-51 is critical for potentiating c-Jun transactivation, an important factor in controlling cell growth, apoptosis, and stress response. Using NMR spectroscopy, we show that the PAGE4 polypeptide chain has local and long-range conformational preferences that are perturbed by site-specific phosphorylation at Thr-51. The population of transient turn-like structures increases upon phosphorylation in an ∼20-residue acidic region centered on Thr-51. This central region therefore becomes more compact and more negatively charged, with increasing intramolecular contacts to basic sequence motifs near the N and C termini. Although flexibility is decreased in the central region of phospho-PAGE4, the polypeptide chain remains highly dynamic overall. PAGE4 utilizes a transient helical structure adjacent to the central acidic region to bind c-Jun with low affinity in vitro. The binding interaction is attenuated by phosphorylation at Thr-51, most likely because of masking the effects of the more compact phosphorylated state. Therefore, phosphorylation of PAGE4 leads to conformational shifts in the dynamic ensemble, with large functional consequences. The changes in the structural ensemble induced by posttranslational modifications are similar conceptually to the conformational switching events seen in some marginally stable (“metamorphic”) folded proteins in response to mutation or environmental triggers.}, number={41}, journal={JOURNAL OF BIOLOGICAL CHEMISTRY}, author={He, Y. N. and Chen, Y. H. and Mooney, S. M. and Rajagopalan, K. and Bhargava, A. and Sacho, E. and keith and Bryan, P. N. and Kulkarni, P. and Orban, J. and et al.}, year={2015}, month={Oct}, pages={25090–25102} }
 @article{mooney_qiu_kim_sacho_rajagopalan_johng_shiraishi_kulkarni_weninger_2014, title={Cancer/Testis Antigen PAGE4, a Regulator of c-Jun Transactivation, Is Phosphorylated by Homeodomain-Interacting Protein Kinase 1, a Component of the Stress-Response Pathway}, volume={53}, ISSN={["0006-2960"]}, DOI={10.1021/bi500013w}, abstractNote={Prostate-associated gene 4 (PAGE4) is a cancer/testis antigen that is typically restricted to the testicular germ cells but is aberrantly expressed in cancer. Furthermore, PAGE4 is developmentally regulated with dynamic expression patterns in the developing prostate and is also a stress-response protein that is upregulated in response to cellular stress. PAGE4 interacts with c-Jun, which is activated by the stress-response kinase JNK1, and plays an important role in the development and pathology of the prostate gland. Here, we have identified homeodomain-interacting protein kinase 1 (HIPK1), also a component of the stress-response pathway, as a kinase that phosphorylates PAGE4 at T51. We show that phosphorylation of PAGE4 is critical for its transcriptional activity since mutating this T residue abolishes its ability to potentiate c-Jun transactivation. In vitro single molecule FRET indicates phosphorylation results in compaction of (still) intrinsically disordered PAGE4. Interestingly, however, while our previous observations indicated that the wild-type nonphosphorylated PAGE4 protein interacted with c-Jun [RajagopalanK. et al. (2014) Biochim, Biophys. Acta1842, 154−16324263171], here we show that phosphorylation of PAGE4 weakens its interaction with c-Jun in vitro. These data suggest that phosphorylation induces conformational changes in natively disordered PAGE4 resulting in its decreased affinity for c-Jun to promote interaction of c-Jun with another, unidentified, partner. Alternatively, phosphorylated PAGE4 may induce transcription of a novel partner, which then potentiates c-Jun transactivation. Regardless, the present results clearly implicate PAGE4 as a component of the stress-response pathway and uncover a novel link between components of this pathway and prostatic development and disease.}, number={10}, journal={BIOCHEMISTRY}, author={Mooney, Steven M. and Qiu, Ruoyi and Kim, John J. and Sacho, Elizabeth J. and Rajagopalan, Krithika and Johng, Dorhyun and Shiraishi, Takumi and Kulkarni, Prakash and Weninger, Keith R.}, year={2014}, month={Mar}, pages={1670–1679} }
 @article{rajagopalan_qiu_mooney_rao_shiraishi_sacho_huang_shapiro_keith_kulkarni_et al._2014, title={The Stress-response protein prostate-associated gene 4, interacts with c-Jun and potentiates its transactivation}, volume={1842}, ISSN={["0006-3002"]}, DOI={10.1016/j.bbadis.2013.11.014}, abstractNote={The Cancer/Testis Antigen (CTA), Prostate-associated Gene 4 (PAGE4), is a stress-response protein that is upregulated in prostate cancer (PCa) especially in precursor lesions that result from inflammatory stress. In cells under stress, translocation of PAGE4 to mitochondria increases while production of reactive oxygen species decreases. Furthermore, PAGE4 is also upregulated in human fetal prostate, underscoring its potential role in development. However, the proteins that interact with PAGE4 and the mechanisms underlying its pleiotropic functions in prostatic development and disease remain unknown. Here, we identified c-Jun as a PAGE4 interacting partner. We show that both PAGE4 and c-Jun are overexpressed in the human fetal prostate; and in cell-based assays, PAGE4 robustly potentiates c-Jun transactivation. Single-molecule Förster resonance energy transfer experiments indicate that upon binding to c-Jun, PAGE4 undergoes conformational changes. However, no interaction is observed in presence of BSA or unilamellar vesicles containing the mitochondrial inner membrane diphosphatidylglycerol lipid marker cardiolipin. Together, our data indicate that PAGE4 specifically interacts with c-Jun and that, conformational dynamics may account for its observed pleiotropic functions. To our knowledge, this is the first report demonstrating crosstalk between a CTA and a proto-oncogene. Disrupting PAGE4/c-Jun interactions using small molecules may represent a novel therapeutic strategy for PCa.}, number={2}, journal={BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR BASIS OF DISEASE}, author={Rajagopalan, K. and Qiu, R. Y. and Mooney, S. M. and Rao, S. and Shiraishi, T. and Sacho, E. and Huang, H. Y. and Shapiro, E. and keith and Kulkarni, P. and et al.}, year={2014}, month={Feb}, pages={154–163} }