title: Functional interaction between cyclooxygenase-2 and p53 in response to an endogenous electrophile.
abstract: Cyclooxygenase-2 (Cox-2) is rapidly expressed by various stimuli and plays a key role in conversion of free arachidonic acid to prostaglandins. We have previously identified 4-hydroxy-2-nonenal (HNE), a lipid peroxidation-derived electrophile, as the potent Cox-2 inducer in rat epithelial RL34 cells and revealed that the HNE-induced Cox-2 expression resulted from the stabilization of Cox-2 mRNA that is mediated by the p38 mitogen-activated protein kinase signaling pathway. In the present study, we investigated an alternative regulatory mechanism of Cox-2 expression mediated by a transcription factor p53. In addition, to characterize the causal role for Cox-2, we examined the effects of Cox-2 overexpression in RL34 cells. To examine whether the HNE-induced Cox-2 expression was mechanistically linked to the p53 expression, we analyzed changes in Cox-2 and p53 expression levels in response to HNE and observed that the Cox-2 levels were inversely correlated with the p53 levels. Down-regulation of p53 followed by the activation of a transcription factor Sp1 was suggested to be involved in the HNE-induced Cox-2 gene expression. To characterize the effect of Cox-2 expression in the cells, we established the Cox-2-overexpressing derivatives of RL34 cells by stable transfection with Cox-2 cDNA. An oligonucleotide microarray analysis revealed a dramatic down-regulation of the proteasome subunit RC1 in the Cox-2 overexpressed cells compared to the empty-vector transfected control cells. Consistent with the Cox-2-mediated down-regulation of proteasome, a moderate reduction of the proteasome activities was observed. This proteasome dysfunction mediated by the Cox-2 overproduction was associated with the enhanced accumulation of p53 and ubiquitinated proteins, leading to the enhanced sensitivity toward electrophiles. These results suggest the existence of a causal link between Cox-2 and p53, which may represent a toxic mechanism of electrophilic lipid peroxidation products.
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kumagai
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Usami
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Nao
authors.initials: N
authors.lastname: Matsukawa
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Fumie
authors.initials: F
authors.lastname: Nakashima
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Miho
authors.initials: M
authors.lastname: Chikazawa
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Shibata
authors.affiliation: Systems Life Sciences, Department of Medical Life Systems, Faculty of Life and Medical Sciences, Doshisha University, 1-3 Miyakodani, Tatara, Kyotanabe, Kyoto 610-0394, Japan.
authors.forename: Noriko
authors.initials: N
authors.lastname: Noguchi
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan. Electronic address: uchidak@agr.nagoya-u.ac.jp.
authors.forename: Koji
authors.initials: K
authors.lastname: Uchida
mesh_terms: D000447:Aldehydes / Q000494:pharmacology; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D002460:Cell Line; D051546:Cyclooxygenase 2 / Q000096:biosynthesis* / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D015227:Lipid Peroxidation / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D011453:Prostaglandins / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000187:drug effects / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis* / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000096:biosynthesis / Q000235:genetics
chemical_list: D000447:Aldehydes; D011453:Prostaglandins; D012333:RNA, Messenger; D016159:Tumor Suppressor Protein p53; D016718:Arachidonic Acid; D051546:Cyclooxygenase 2; D048051:p38 Mitogen-Activated Protein Kinases; D046988:Proteasome Endopeptidase Complex; C027576:4-hydroxy-2-nonenal
keywords: 4-Hydroxy-2-nonenal; Cyclooxygenase; Lipid peroxidation; Proteasome; Sp1; p53