Ligands of peroxisome proliferator-activated receptor inhibit homocysteine-induced DNA methylation of inducible nitric oxide synthase gene.
Homocysteine (Hcy) is a risk factor for atherosclerosis. It is generally accepted that inducible nitric oxide synthase (iNOS) is a key enzyme in the regulation of vascular disease. The aim of the present study is to investigate the effects of peroxisome proliferator-activated receptor ligands on iNOS in the presence of Hcy in human monocytes. Foam cells, induced by oxidize low density lipoprotein (ox-LDL) and phorbol myristate acetate (PMA) in the presence of different concentrations of Hcy, clofibrate and pioglitazone in human monocytes for 4 d, were examined by oil red O staining. The activity of iNOS was detected by real-time quantitative reverse transcription-polymerase chain reaction and Western blot analysis. The capability of DNA methylation was measured by assaying endogenous C5 DNA methyltransferase (C5MTase) activity, and the iNOS promoter methylation level was determined by quantitative MethyLight assays. The results indicated that Hcy increased the activity of C5MTase and the level of iNOS gene DNA methylation, resulting in a decrease of iNOS expression. Clofibrate and pioglitazone could antagonize the hcy effect on iNOS expression through DNA methylation, resulting in attenuation of iNOS transcription. These findings suggested that Hcy decreased the expression of iNOS by elevating iNOS DNA methylation levels, which can repress the transcription of some genes. Peroxisome proliferator-activated receptor alpha/gamma ligands can down-regulate iNOS DNA methylation, and could be useful for preventing Hcy-induced atherosclerosis by repressing iNOS expression.
Jiang
Yideng
Y
Department of Pathology, Ningxia Medical College, Yinchuan 750004, China. jwcjyd@163.com
Zhang
Jianzhong
J
Xiong
Jiantuan
J
Cao
Jun
J
Li
Guizhong
G
Wang
Shuren
S
D001391:Azo Compounds / Q000494:pharmacology; D001483:Base Sequence; D002994:Clofibrate / Q000494:pharmacology; D019175:DNA Methylation; D015254:DNA Modification Methylases / Q000378:metabolism; D017931:DNA Primers / Q000737:chemistry; D005487:Foam Cells / Q000378:metabolism; D006710:Homocysteine / Q000737:chemistry*; D006801:Humans; D008024:Ligands; D008969:Molecular Sequence Data; D009000:Monocytes / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000235:genetics* / Q000378:metabolism*; D047492:Peroxisome Proliferator-Activated Receptors / Q000378:metabolism*; D000077205:Pioglitazone; D045162:Thiazolidinediones / Q000494:pharmacology
D001391:Azo Compounds; D017931:DNA Primers; D008024:Ligands; D047492:Peroxisome Proliferator-Activated Receptors; D045162:Thiazolidinediones; D006710:Homocysteine; D052247:Nitric Oxide Synthase Type II; D015254:DNA Modification Methylases; C011049:oil red O; D002994:Clofibrate; D000077205:Pioglitazone