| Summary: | 碩士 === 國立成功大學 === 藥理學研究所 === 89 === Arachidonate 12(S)-lipoxygenase in the platelet is the first mammalian lipoxygenase discovered. It catalyzes the transformation of arachidonic acid into 12(S)-HETE. 12(S)-HETE may play a significant role in the pathogenesis of some epidermal and epithelial inflammation. In study the regulation of 12(S)-lipoxygenase, we previously reported that PMA increased 12(S)-lipoxygenase mRNA, and enzyme activity. PMA through Raf-ERK pathway and induced the expression of c-Jun. Coimmunoprecipitation experiments revealed that PD098059, an MEK inhibitor, inhibited PMA-induced the interaction between c-jun and Sp1. To determine whether protein phosphorylation could plays a functional role in PMA-induced 12(S)-lipoxygenase, expression vectors of phosphatase 2B (PP2B) and casein kinase 2 (CK II) were used. Pretreatment of cells with a PP2B inhibitor, cyclosporin A or overexpression of CK2 could inhibit the PMA-induced 12(S)-lpioxygenase promoter activity. Furthermore, pretreatment of cells with a CK 2 inhibitor, DRB, or overexpression of PP2B could enhance PMA responses. Cyclosporin A did not affect PMA-induced ERK activation, c-jun biosynthesis and nuclear translocation, but it inhibited the interaction between c-jun and Sp1. Transfection of cells with TAM-67-M3 which Thr-231, Ser243 and Ser249 was changed in to aspartic acid could inhibit the pRSVjun-induced 12(S)-lipoxygenase promoter activity more efficienctly than that with TAM-67. These results revealed that (1) the interaction between c-jun and Sp1 might be regulated by a phosphorylation/dphosphorylation mechanism. (2) Thr-231, Ser243 and Ser249 in C termimus of c-Jun may play an essential role in the interaction between c-Jun and Sp1. (3) CK 2 and PP2B have opposite effect on the regulation of 12(S)-lipoxygenase in A431 cells.
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