Functional role of extracellular signal-regulated kinase activation and c-Jun induction in phorbol ester-induced promoter activation of human 12(S)-lipoxygenase gene

Abstract

The functional role of mitogen-activated protein kinase (MAPK) signaling and c-Jun induction in phorbol 12-myristate 13-acetate (PMA)-induced human 12(S)-lipoxygenase gene expression was studied in human epidermoid carcinoma A431 cells. Among the family of MAPK, PMA only increased the activity of extracellular signal-regulated kinase (ERK). Treatment of cells with PD98059, which is an inhibitor of mitogen-activated protein kinase kinase (MEK), decreased the PMA-induced expression of 12(S)-lipoxygenase. Transfection of cells with Ras, Raf and ERK2 dominant negative mutants inhibited the PMA-induced promoter activation of the 12(S)-lipoxygenase gene in all cases. PMA-induced expression of c-Jun was inhibited by pretreatment with PD98059. Following treatment with PMA, the interaction between c-Jun and simian virus 40 promoter factor 1 (Sp1) in cells increased with time. Enhancement of binding between the c-Jun-Sp1 complex and the Sp1 oligonucleotide was observed in cells treated with PMA, suggesting the possible interaction of c-Jun-Sp1 with GC-rich binding sites in the gene promoter. These results indicate that PMA treatment induced ERK activation mainly through the Raf-MEK-ERK signaling pathway following induction of c-Jun expression, and the formation of the c-Jun-Sp1 complex. Finally, PMA activated the promoter activity of the 12(S)-lipoxygenase gene in cells overexpressing protein kinase C (PKC)delta but not PKCalpha, indicating that PKCdelta played the functional role in mediating the gene activation of 12(S)-lipoxygenase induced by PMA.

Induction of Disease-associated Keratin 16 Gene Expression by Epidermal Growth Factor Is Regulated through Cooperation of Transcription Factors Sp1 and c-Jun

“…In our system of the keratin 16 promoter, the synergistic mechanism of transactivation of Sp1 and c-Jun seems to be similar to the above-mentioned examples. On the other hand, we found previously that the direct interaction between Sp1 and c-Jun induced by EGF (34) and phorbol 12-myristate 13-acetate (35) promoter DNA was observed in the 12(S)-lipoxygenase gene (22).…”

PP2B-mediated Dephosphorylation of c-Jun C Terminus Regulates Phorbol Ester-induced c-Jun/Sp1 Interaction in A431 Cells

“…Although PMA enhances the dephosphorylation of c-Jun C terminus (Boyle et al, 1991), resulting in an increased DNA binding, the functional role of the dephosphorylated c-Jun C terminus in regulating a proteinprotein interaction is not clear. We reported previously that PMA induces the interaction between c-Jun and Sp1 in the same manner as that induced by epidermal growth factor (EGF), indicating that protein kinase C activation could also induce the interaction between c-Jun and Sp1 (Chen et al, 2002). Because EGF and PMA induce the interaction between c-Jun and Sp1 via the C-terminal domain of c-Jun Chen et al, 2002), there exists a possibility that the dephosphorylation of the C-terminal cluster is essential for the interaction between c-Jun and Sp1.…”

Activation of Extracellular Signal-Regulated Kinase Signaling by Epidermal Growth Factor Mediates c-Jun Activation and p300 Recruitment in Keratin 16 Gene Expression

“…We found previously that the direct interaction between Sp1 and c-Jun induced by EGF and phorbol 12-myristate 13-acetate (Chen et al, 2002) cooperatively activated expression of the 12(S)-lipoxygenase gene and that Sp1 may function as an anchor protein to recruit c-Jun to the promoter, thus activating the transcriptional activity of the 12(S)-lipoxygenase gene. In the present study, we compared the effect of the c-Jun dominant-negative mutant TAM-67 on the gene regulation of 12(S)-lipoxygenase in A431 cells and keratin 16 in HaCaT cells.…”