Heme oxygenase-1 attenuates interleukin-1beta-induced nitric oxide synthase expression in vascular smooth muscle cells.
Heme oxygenase-1 (HO-1) has been implicated in antioxidant and anti-inflammatory actions. To characterize the role of HO-1 in the vascular inflammatory response, we examined the effect of HO-1 on the expression of inducible nitric oxide synthase (iNOS) induced by interleukin-1beta (IL-1beta) in rat vascular smooth muscle cells (VSMCs). Western blot analysis demonstrated that IL-1beta-induced iNOS expression was significantly reduced by hemin cotreatment or adenovirus-mediated HO-1 gene transfer. Scavenging carbon monoxide (CO), one of the by-products of heme degradation by HO-1, significantly attenuated HO-1-mediated suppression of iNOS gene induction as revealed by Northern blot analysis. Exposure of cells to CO or a CO donor, the tricarbonyldichlororuthenium(II) dimer, also markedly inhibited IL-1beta-induced iNOS expression. Transient transfection experiments with a reporter gene construct carrying the rat iNOS gene promoter demonstrated that IL-1beta-induced promoter activity was substantially reduced by cotreatment with CO or a CO donor. Furthermore, the effects of CO on iNOS gene promoter activity and protein expression were diminished by cotreatment with the specific guanylate cyclase inhibitor, 1H-[1,2,4]oxadiazolo-(4,3-a)quinoxalin-1-one. These data support the finding that HO-1 attenuates IL-1beta-induced iNOS gene expression in VSMCs. CO appears to mediate the suppressive effect of HO-1, at least in part, through downregulating transcriptional activation of the iNOS gene via a cGMP-dependent pathway.
Yang
Nian-Chung
NC
Division of Cardiovascular Research, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan, ROC.
Lu
Liang-Huei
LH
Kao
Yung-Hsi
YH
Chau
Lee-Young
LY
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D001011:Aorta / Q000473:pathology; D015152:Blotting, Northern; D015153:Blotting, Western; D002248:Carbon Monoxide / Q000737:chemistry; D002470:Cell Survival; D002478:Cells, Cultured; D018076:DNA, Complementary / Q000378:metabolism; D003676:Deferoxamine / Q000737:chemistry; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation; D018014:Gene Transfer Techniques; D006419:Heme Oxygenase (Decyclizing) / Q000378:metabolism / Q000502:physiology*; D051547:Heme Oxygenase-1; D006454:Hemoglobins / Q000737:chemistry; D007375:Interleukin-1 / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000201:enzymology*; D032389:Myocytes, Smooth Muscle / Q000166:cytology; D019001:Nitric Oxide Synthase / Q000096:biosynthesis*; D052247:Nitric Oxide Synthase Type II; D009573:Nitrites / Q000378:metabolism; D009942:Organometallic Compounds / Q000737:chemistry; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D015533:Transcriptional Activation; D014162:Transfection
D018076:DNA, Complementary; D006454:Hemoglobins; D007375:Interleukin-1; D009573:Nitrites; D009942:Organometallic Compounds; D012333:RNA, Messenger; C447082:tricarbonyldichlororuthenium (II) dimer; D002248:Carbon Monoxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1; D003676:Deferoxamine