title: PP2B-mediated dephosphorylation of c-Jun C terminus regulates phorbol ester-induced c-Jun/Sp1 interaction in A431 cells.
abstract: The c-Jun/Sp1 interaction is essential for growth factor- and phorbol 12-myristate 13-acetate (PMA)-induced genes expression, including human 12(S)-lipoxygenase, keratin 16, cytosolic phospholipase A2, p21(WAF1/CIP1), and neuronal nicotinic acetylcholine receptor beta4. Here, we examined the mechanism underlying the PMA-induced regulation on the interaction between c-Jun and Sp1. We found that treatment of cells with PMA induced a dephosphorylation at the C terminus of c-Jun at Ser-243 and a concomitant inhibition of PP2B by using PP2B small interfering RNA, resulting in reduction of PMA-induced gene expression as well as the c-Jun/Sp1 interaction. The c-Jun mutant TAM-67-3A, which contains three substitute alanines at Thr-231, Ser-243, and Ser-249 compared with TAM-67, binds more efficaciously with Sp1 and is about twice as efficacious as TAM-67 in inhibiting the PMA-induced activation of the 12(S)-lipoxygenase promoter. Importantly, PP2B not only dephosphorylates the c-Jun at Ser-243 but also interacts with c-Jun in PMA-treated cells. PMA stimulates the association of the PP2B/c-Jun/Sp1 complex with the promoter. These findings indicate the dephosphorylation of c-Jun C terminus is required for the c-Jun/Sp1 interaction and reveal that PP2B plays an important role in regulating c-Jun/Sp1 interaction in PMA-induced gene expression.
authors.affiliation: Department of Pharmacology, College of Medicine, Center for Gene Regulation and Signal Transduction Research, National Cheng Kung University, Tainan 701, Taiwan.
authors.forename: Ben-Kuen
authors.initials: BK
authors.lastname: Chen
authors.forename: Chi-Chen
authors.initials: CC
authors.lastname: Huang
authors.forename: Wei-Chiao
authors.initials: WC
authors.lastname: Chang
authors.forename: Yun-Ju
authors.initials: YJ
authors.lastname: Chen
authors.forename: Ushio
authors.initials: U
authors.lastname: Kikkawa
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Nakahama
authors.forename: Ikuo
authors.initials: I
authors.lastname: Morita
authors.forename: Wen-Chang
authors.initials: WC
authors.lastname: Chang
mesh_terms: D019703:Calcineurin / Q000378:metabolism*; D065095:Calcineurin Inhibitors; D045744:Cell Line, Tumor; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D010766:Phosphorylation / Q000187:drug effects; D011401:Promoter Regions, Genetic / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D016755:Proto-Oncogene Proteins c-jun / Q000737:chemistry* / Q000378:metabolism*; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
chemical_list: D065095:Calcineurin Inhibitors; D016755:Proto-Oncogene Proteins c-jun; D016329:Sp1 Transcription Factor; D019703:Calcineurin; D013755:Tetradecanoylphorbol Acetate