Lex, thereby maintaining the chromatin structure [17,18]. They may also inhibit the functional interaction of the general transcription factors with the promoter [16]. The chicken ovalbumin upstream promoter-transcription factors (COUP-TFs) are orphan members of nuclear receptor superfamily that activate or repress gene transcription by directly binding DNA sequence [19]. There are three members of the human COUP-TF family: COUP-TF I (NR2F1), COUP-TF II (NR2F2), and ErbA-related protein 2 (NR2F6) [20]. COUP-TF I and COUP-TF II proteins are 95 homologous and evolutionarily conserved in the DNA binding domain as well as the ligandbinding domain, mainly differing at the N-terminus (reviewed inCOUP-TF II Inhibits AR Transactivation[19]). COUP-TF I is more highly expressed in neuronal tissues of the central and peripheral nervous systems, whereas the COUPTF II is more highly expressed in developing organs such as the lung, kidney, pancreas and prostate [20,21]. ErbA-related protein 2 is less conserved and little is known about its expression and function [22]. COUP-TF interacts with other nuclear receptors, including estrogen receptor (ER), the retinoid X receptor (RXR), peroxisome proliferator-activated receptors (PPAR), and the vitamin D receptor (VDR) [23?7]. In general, COUP-TF inhibits the transcriptional activity of other nuclear receptors by competing for their DNA binding sites or by heterodimerization with the class II nuclear receptor heterodimer partner retinoid X receptor, thereby preventing gene expression [28]. In addition, like thyroid hormone receptor and retinoic acid receptor, unliganded DNA-bound COUP-TF I represses gene expression by an active silencing domain within the ligand-binding domain that recruits corepressors (i. e., NCoR and SMRT), a process called active repression [29]. Finally, COUP-TF can also repress transcription by directly binding to the ligand-binding domain of nuclear hormone receptors (transrepression; [30,31]). In previous reports, COUPTF was related with the development of various cancer including breast cancer [24,32?4], lung cancer, and adrenal cancer progression [35?7]. In the present study, we 520-26-3 biological activity demonstrate that COUP-TF II represses the transactivation of AR in prostate cancer cells, resulting in the inhibition of androgen-dependent cell growth. COUP-TF II directly binds AR, preventing the N/C terminal interaction of AR. Furthermore, COUP-TF II inhibits the ligandinduced recruitment of AR to the PSA promoter and competes with AR coactivators to modulate AR transactivation. All together, our results suggest COUP-TF II as a potent AR corepressor and provide an insight into the role of COUP-TF II in prostate cancers.II full length and deletion mutants, AF1, DBD+hinge (DBDh), and DAF1 regions, were constructed by self-ligation of SmaI/ XhoI-, SphI/XhoI-, and EcoRI/SmaI-digested fragment from get Madecassoside GST-COUP-TF II full length, respectively. The mammalian expression plasmids VP-AR1-660 and GAL-AR624-919 and the reporter construct 5XGAL4-Luc3 (originally from Dr. Donald McDonnell) were kindly provided as gifts by Dr. Elizabeth M. Wilson (University of North Carolina) [39].Preparation of Recombinant AdenovirusFor the ectopic expression of the mouse COUP-TF II, an adenoviral delivery system was used [40]. Briefly, the COUP-TF II cDNA was cloned into pAdTrack-CMV shuttle vector. Homologous recombination was performed by transformation of adEasy-BJ5138 competent cells with pAdTrack-CMV-COUP-TF II together with ad.Lex, thereby maintaining the chromatin structure [17,18]. They may also inhibit the functional interaction of the general transcription factors with the promoter [16]. The chicken ovalbumin upstream promoter-transcription factors (COUP-TFs) are orphan members of nuclear receptor superfamily that activate or repress gene transcription by directly binding DNA sequence [19]. There are three members of the human COUP-TF family: COUP-TF I (NR2F1), COUP-TF II (NR2F2), and ErbA-related protein 2 (NR2F6) [20]. COUP-TF I and COUP-TF II proteins are 95 homologous and evolutionarily conserved in the DNA binding domain as well as the ligandbinding domain, mainly differing at the N-terminus (reviewed inCOUP-TF II Inhibits AR Transactivation[19]). COUP-TF I is more highly expressed in neuronal tissues of the central and peripheral nervous systems, whereas the COUPTF II is more highly expressed in developing organs such as the lung, kidney, pancreas and prostate [20,21]. ErbA-related protein 2 is less conserved and little is known about its expression and function [22]. COUP-TF interacts with other nuclear receptors, including estrogen receptor (ER), the retinoid X receptor (RXR), peroxisome proliferator-activated receptors (PPAR), and the vitamin D receptor (VDR) [23?7]. In general, COUP-TF inhibits the transcriptional activity of other nuclear receptors by competing for their DNA binding sites or by heterodimerization with the class II nuclear receptor heterodimer partner retinoid X receptor, thereby preventing gene expression [28]. In addition, like thyroid hormone receptor and retinoic acid receptor, unliganded DNA-bound COUP-TF I represses gene expression by an active silencing domain within the ligand-binding domain that recruits corepressors (i. e., NCoR and SMRT), a process called active repression [29]. Finally, COUP-TF can also repress transcription by directly binding to the ligand-binding domain of nuclear hormone receptors (transrepression; [30,31]). In previous reports, COUPTF was related with the development of various cancer including breast cancer [24,32?4], lung cancer, and adrenal cancer progression [35?7]. In the present study, we demonstrate that COUP-TF II represses the transactivation of AR in prostate cancer cells, resulting in the inhibition of androgen-dependent cell growth. COUP-TF II directly binds AR, preventing the N/C terminal interaction of AR. Furthermore, COUP-TF II inhibits the ligandinduced recruitment of AR to the PSA promoter and competes with AR coactivators to modulate AR transactivation. All together, our results suggest COUP-TF II as a potent AR corepressor and provide an insight into the role of COUP-TF II in prostate cancers.II full length and deletion mutants, AF1, DBD+hinge (DBDh), and DAF1 regions, were constructed by self-ligation of SmaI/ XhoI-, SphI/XhoI-, and EcoRI/SmaI-digested fragment from GST-COUP-TF II full length, respectively. The mammalian expression plasmids VP-AR1-660 and GAL-AR624-919 and the reporter construct 5XGAL4-Luc3 (originally from Dr. Donald McDonnell) were kindly provided as gifts by Dr. Elizabeth M. Wilson (University of North Carolina) [39].Preparation of Recombinant AdenovirusFor the ectopic expression of the mouse COUP-TF II, an adenoviral delivery system was used [40]. Briefly, the COUP-TF II cDNA was cloned into pAdTrack-CMV shuttle vector. Homologous recombination was performed by transformation of adEasy-BJ5138 competent cells with pAdTrack-CMV-COUP-TF II together with ad.