Heme oxygenase-1 is a cGMP-inducible endothelial protein and mediates the cytoprotective action of nitric oxide.
Inducible heme oxygenase (HO-1) has recently been recognized as an antioxidant and cytoprotective gene. By use of Western blotting, cell viability analysis, and antisense technique, the present study investigates the involvement of HO-1 in endothelial protection induced by the clinically used nitric oxide (NO) donor molsidomine (specifically, its active metabolite 3-morpholinosydnonimine [SIN-1]) and the second messenger cGMP. In bovine pulmonary artery endothelial cells, SIN-1 and S-nitroso-N-acetyl-D,L-penicillamine (SNAP) at 1 to 100 micromol/L induced the synthesis of HO-1 protein in a concentration-dependent fashion up to 3-fold over basal levels. HO-1 induction by SIN-1 was inhibited in the presence of the NO scavenger phenyl-4,4,5,5,-tetramethylimidazoline-1-oxyl-3-oxide and the soluble guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazole[4, 3-a]quinoxalin-1-one. 8-Bromo-cGMP (1 to 100 micromol/L) and dibutyryl cGMP (1 to 100 micromol/L) as well as the activator of particulate guanylyl cyclase atrial natriuretic peptide (1 to 100 nmol/L) produced increases in HO-1 protein similar to those produced by SIN-1. SIN-1 and 8-bromo-cGMP increased heme oxygenase activity (bilirubin formation). Cytoprotection by NO donors was abrogated in the presence of the heme oxygenase inhibitor tin protoporphyrin IX. Pretreatment of cells with a phosphorothioate-linked HO-1 antisense oligonucleotide prevented protection by SIN-1 or 8-bromo-cGMP against tumor necrosis factor-alpha cytotoxicity, whereas sense and scrambled HO-1 were without effect under these conditions. Our results show for the first time that HO-1 is a cGMP-sensitive endothelial gene and establish conclusively a causal relationship between HO-1 induction and endothelial protection by the NO/cGMP system. By targeting cytoprotective HO-1, NO donors may therefore be expected to induce antioxidant, antiatherogenic, and anti-inflammatory effects.
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Department of Pharmacology, School of Pharmacy, Martin Luther University, Halle, Germany.
Abate
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Dennery
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Schröder
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D000818:Animals; D002417:Cattle; D002470:Cell Survival; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000201:enzymology*; D004790:Enzyme Induction / Q000187:drug effects; D006419:Heme Oxygenase (Decyclizing) / Q000096:biosynthesis / Q000502:physiology*; D008981:Molsidomine / Q000031:analogs & derivatives / Q000494:pharmacology; D009569:Nitric Oxide / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D010396:Penicillamine / Q000031:analogs & derivatives / Q000494:pharmacology; D011651:Pulmonary Artery; D015290:Second Messenger Systems
D020030:Nitric Oxide Donors; C110881:S-nitro-N-acetylpenicillamine; C016276:8-bromocyclic GMP; D009569:Nitric Oxide; C002385:linsidomine; D008981:Molsidomine; D006419:Heme Oxygenase (Decyclizing); D010396:Penicillamine; D006152:Cyclic GMP