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J Biol Chem. 2016 Nov 11;291(46):24076-24084. Epub 2016 Sep 27.

Formation of Nitric Oxide by Aldehyde Dehydrogenase-2 Is Necessary and Sufficient for Vascular Bioactivation of Nitroglycerin.

Author information

1
From the Institute of Pharmaceutical Sciences, Department of Pharmacology and Toxicology, University of Graz, A-8010 Graz, Austria.
2
the Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, 8010 Graz, Austria, and.
3
the Department of Pharmacology and Toxicology, Ruhr University Bochum, 44780 Bochum, Germany.
4
From the Institute of Pharmaceutical Sciences, Department of Pharmacology and Toxicology, University of Graz, A-8010 Graz, Austria, mayer@uni-graz.at.

Abstract

Aldehyde dehydrogenase-2 (ALDH2) catalyzes vascular bioactivation of the antianginal drug nitroglycerin (GTN), resulting in activation of soluble guanylate cyclase (sGC) and cGMP-mediated vasodilation. We have previously shown that a minor reaction of ALDH2-catalyzed GTN bioconversion, accounting for about 5% of the main clearance-based turnover yielding inorganic nitrite, results in direct NO formation and concluded that this minor pathway could provide the link between vascular GTN metabolism and activation of sGC. However, lack of detectable NO at therapeutically relevant GTN concentrations (≤1 μm) in vascular tissue called into question the biological significance of NO formation by purified ALDH2. We addressed this issue and used a novel, highly sensitive genetically encoded fluorescent NO probe (geNOp) to visualize intracellular NO formation at low GTN concentrations (≤1 μm) in cultured vascular smooth muscle cells (VSMC) expressing an ALDH2 mutant that reduces GTN to NO but lacks clearance-based GTN denitration activity. NO formation was compared with GTN-induced activation of sGC. The addition of 1 μm GTN to VSMC expressing either wild-type or C301S/C303S ALDH2 resulted in pronounced intracellular NO elevation, with maximal concentrations of 7 and 17 nm, respectively. Formation of GTN-derived NO correlated well with activation of purified sGC in VSMC lysates and cGMP accumulation in intact porcine aortic endothelial cells infected with wild-type or mutant ALDH2. Formation of NO and cGMP accumulation were inhibited by ALDH inhibitors chloral hydrate and daidzin. The present study demonstrates that ALDH2-catalyzed NO formation is necessary and sufficient for GTN bioactivation in VSMC.

KEYWORDS:

aldehyde dehydrogenase-2; cyclic GMP (cGMP); metabolism; mutagenesis in vitro; nitric oxide; nitroglycerin; site-directed mutagenesis; vascular smooth muscle cells

PMID:
27679490
PMCID:
PMC5104933
DOI:
10.1074/jbc.M116.752071
[Indexed for MEDLINE]
Free PMC Article

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