Dual function of protein kinase C (PKC) in 12-O-tetradecanoylphorbol-13- acetate (TPA)-induced manganese superoxide dismutase (MnSOD) expression: Activation of creb and foxo3a by PKC-α phosphorylation and by PKC-mediated inactivation of akt, respectively

Youn Wook Chung, Ha Kun Kim, Ick Young Kim, Moon B. Yim, P. Boon Chock

Research output: Contribution to journalArticle

34 Citations (Scopus)

Abstract

12-O-tetradecanoylphorbol-13-acetate (TPA) has been shown to induce transcriptional activation of human manganese superoxide dismutase (MnSOD) mRNA in human lung carcinoma cells, A549, mediated by a protein kinase C (PKC)-dependent activation of cAMP-responsive element-binding protein (CREB)-1/ATF-1-like factors. In this study, we showed that MnSOD protein expression was elevated in response to TPA or TNF-α, but not to hydrogen peroxide treatment. TPA-induced generation of reactive oxygen species (ROS) was blocked by pretreatment of the PKC inhibitor BIM and NADPH oxidase inhibitor DPI. Small interfering RNA (siRNA) experiments indicated that knocking down the NADPH oxidase components e.g. Rac1, p22 phox, p67 phox, and NOXO1 in A549 cells impaired TPA-induced MnSOD expression. To identify the PKC isozyme involved, we used a sod2 gene response reporter plasmid, pSODLUC-3340-I2E-C, capable of sensing the effect of TNF-α and TPA, to monitor the effects of PKC isozyme-specific inhibitors and siRNA-induced knockdown of specific PKC isozyme. Our data indicate that TPA-induced MnSOD expression was independent of p53 and most likely mediated by PKC-α-, and -ε-dependent signaling pathways. Furthermore, siRNA-induced knock-down of CREB and Forkhead box classO(FOXO)3a led to a reductionin TPA-induced MnSOD gene expression. Together, our results revealed that TPA up-regulates, in part, two PKC-dependent transcriptional pathways to induce MnSOD expression. One pathway involves PKC-α catalyzed phosphorylation of CREB and the other involves a PKC-mediated the PP2A catalyzed dephosphorylation of Akt at Ser 473 which in turn leads to FOXO3a Ser 253dephosphorylation and its activation.

Original languageEnglish
Pages (from-to)29681-29690
Number of pages10
JournalJournal of Biological Chemistry
Volume286
Issue number34
DOIs
Publication statusPublished - 2011 Aug 26

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ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

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