Inhibition of basal and interleukin-1-induced VCAM-1 expression by phospholipid hydroperoxide glutathione peroxidase and 15-lipoxygenase in rabbit aortic smooth muscle cells.
Cytokines or hydroperoxides upregulate cell adhesion molecules (CAM) in early stages of atherosclerosis. VCAM-1 expression was therefore investigated in rabbit aortic smooth muscle cells (SMC) stably transfected either with phospholipid hydroperoxide glutathione peroxidase (PHGPx; SMCPHGPx) as a hydroperoxide-reducing enzyme or with 15-lipoxygenase (15-LOX; SMCLOX) as a hydroperoxide-producing enzyme. Transfected cells showed up to 3-fold enhanced PHGPx and a marked LOX activity, respectively, that was absent in controls. Intracellular hydroperoxides were 6-fold higher in SMCLOX than in SMC or SMCPHGPx. Intracellular protein thiols were decreased by 50 and 90% in SMCPHGPx and SMCLOX, respectively. Glutathione mixed disulfides were tentatively increased from SMC via SMCPHGPx to SMCLOX, accordingly. Thiol reduction with tris(2-carboxyethyl)phosphine completely restored protein thiols in SMCPHGPx, whereas in SMCLOX only 60% of control values were recovered. Basal VCAM-1 mRNA levels were decreased by 50% in SMCPHGPx and 75% in SMCLOX. VCAM-1-inducibility was abrogated in SMCLOX but not in SMCPHGPx. Accordingly, NFkappaB-driven reporter gene activation by IL-1 was unaffected in SMCPHGPx but abolished in SMCLOX. The data confirm that PHGPx overexpression dampens CAM expression either by lowering stimulatory hydroperoxides or by using hydroperoxides for protein modification. But hydroperoxides, when constitutively overproduced as in SMCLOX, inhibit CAM expression and render cells refractory to IL-1 stimulation likely due to oxidation of protein thiols of the signaling system.
Banning
Antje
A
Department of Vitamins and Atherosclerosis, German Institute of Human Nutrition, Potsdam-Rehbrücke, Germany.
Schnurr
Kerstin
K
Böl
Gaby Fleur
GF
Kupper
Dagmar
D
Müller-Schmehl
Katrin
K
Viita
Helena
H
Ylä-Herttuala
Seppo
S
Brigelius-Flohé
Regina
R
D000818:Animals; D001011:Aorta / Q000166:cytology; D001093:Arachidonate 15-Lipoxygenase / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D005786:Gene Expression Regulation / Q000187:drug effects*; D005978:Glutathione / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000235:genetics / Q000378:metabolism*; D007375:Interleukin-1 / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D008969:Molecular Sequence Data; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D010084:Oxidation-Reduction; D000080662:Phospholipid Hydroperoxide Glutathione Peroxidase; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011817:Rabbits; D015533:Transcriptional Activation; D014162:Transfection; D019010:Vascular Cell Adhesion Molecule-1 / Q000235:genetics*
D007375:Interleukin-1; D016328:NF-kappa B; D012333:RNA, Messenger; D019010:Vascular Cell Adhesion Molecule-1; D000080662:Phospholipid Hydroperoxide Glutathione Peroxidase; D005979:Glutathione Peroxidase; D001093:Arachidonate 15-Lipoxygenase; D005978:Glutathione