Cellular hypomethylation is associated with impaired nitric oxide production by cultured human endothelial cells. 2012

M Barroso, and M S Rocha, and R Esse, and I Gonçalves, and A Q Gomes, and T Teerlink, and C Jakobs, and H J Blom, and J Loscalzo, and I Rivera, and I Tavares de Almeida, and R Castro
Research Institute for Medicines and Pharmaceutical Sciences (iMed.UL), Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal.

Hyperhomocysteinemia (HHcy) is a risk factor for vascular disease, but the underlying mechanisms remain incompletely defined. Reduced bioavailability of nitric oxide (NO) is a principal manifestation of underlying endothelial dysfunction, which is an initial event in vascular disease. Inhibition of cellular methylation reactions by S-adenosylhomocysteine (AdoHcy), which accumulates during HHcy, has been suggested to contribute to vascular dysfunction. However, thus far, the effect of intracellular AdoHcy accumulation on NO bioavailability has not yet been fully substantiated by experimental evidence. The present study was carried out to evaluate whether disturbances in cellular methylation status affect NO production by cultured human endothelial cells. Here, we show that a hypomethylating environment, induced by the accumulation of AdoHcy, impairs NO production. Consistent with this finding, we observed decreased eNOS expression and activity, but, by contrast, enhanced NOS3 transcription. Taken together, our data support the existence of regulatory post-transcriptional mechanisms modulated by cellular methylation potential leading to impaired NO production by cultured human endothelial cells. As such, our conclusions may have implications for the HHcy-mediated reductions in NO bioavailability and endothelial dysfunction.

UI MeSH Term Description Entries
D008745 Methylation Addition of methyl groups. In histo-chemistry methylation is used to esterify carboxyl groups and remove sulfate groups by treating tissue sections with hot methanol in the presence of hydrochloric acid. (From Stedman, 25th ed) Methylations
D009569 Nitric Oxide A free radical gas produced endogenously by a variety of mammalian cells, synthesized from ARGININE by NITRIC OXIDE SYNTHASE. Nitric oxide is one of the ENDOTHELIUM-DEPENDENT RELAXING FACTORS released by the vascular endothelium and mediates VASODILATION. It also inhibits platelet aggregation, induces disaggregation of aggregated platelets, and inhibits platelet adhesion to the vascular endothelium. Nitric oxide activates cytosolic GUANYLATE CYCLASE and thus elevates intracellular levels of CYCLIC GMP. Endogenous Nitrate Vasodilator,Mononitrogen Monoxide,Nitric Oxide, Endothelium-Derived,Nitrogen Monoxide,Endothelium-Derived Nitric Oxide,Monoxide, Mononitrogen,Monoxide, Nitrogen,Nitrate Vasodilator, Endogenous,Nitric Oxide, Endothelium Derived,Oxide, Nitric,Vasodilator, Endogenous Nitrate
D002478 Cells, Cultured Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others. Cultured Cells,Cell, Cultured,Cultured Cell
D005786 Gene Expression Regulation Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control (induction or repression) of gene action at the level of transcription or translation. Gene Action Regulation,Regulation of Gene Expression,Expression Regulation, Gene,Regulation, Gene Action,Regulation, Gene Expression
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D001120 Arginine An essential amino acid that is physiologically active in the L-form. Arginine Hydrochloride,Arginine, L-Isomer,DL-Arginine Acetate, Monohydrate,L-Arginine,Arginine, L Isomer,DL Arginine Acetate, Monohydrate,Hydrochloride, Arginine,L Arginine,L-Isomer Arginine,Monohydrate DL-Arginine Acetate
D012435 S-Adenosylhomocysteine 5'-S-(3-Amino-3-carboxypropyl)-5'-thioadenosine. Formed from S-adenosylmethionine after transmethylation reactions. S Adenosylhomocysteine,Adenosylhomocysteine, S
D014652 Vascular Diseases Pathological processes involving any of the BLOOD VESSELS in the cardiac or peripheral circulation. They include diseases of ARTERIES; VEINS; and rest of the vasculature system in the body. Disease, Vascular,Diseases, Vascular,Vascular Disease
D042783 Endothelial Cells Highly specialized EPITHELIAL CELLS that line the HEART; BLOOD VESSELS; and lymph vessels, forming the ENDOTHELIUM. They are polygonal in shape and joined together by TIGHT JUNCTIONS. The tight junctions allow for variable permeability to specific macromolecules that are transported across the endothelial layer. Capillary Endothelial Cells,Lymphatic Endothelial Cells,Vascular Endothelial Cells,Capillary Endothelial Cell,Cell, Capillary Endothelial,Cell, Endothelial,Cell, Lymphatic Endothelial,Cell, Vascular Endothelial,Cells, Capillary Endothelial,Cells, Endothelial,Cells, Lymphatic Endothelial,Cells, Vascular Endothelial,Endothelial Cell,Endothelial Cell, Capillary,Endothelial Cell, Lymphatic,Endothelial Cell, Vascular,Endothelial Cells, Capillary,Endothelial Cells, Lymphatic,Endothelial Cells, Vascular,Lymphatic Endothelial Cell,Vascular Endothelial Cell
D052250 Nitric Oxide Synthase Type III A CALCIUM-dependent, constitutively-expressed form of nitric oxide synthase found primarily in ENDOTHELIAL CELLS. ECNOS Enzyme,ENOS Enzyme,Endothelial Constitutive Nitric Oxide Synthase,Endothelial Nitric Oxide Synthase,Nitric Oxide Synthase, Type III

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