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Perturbation of Human Coronary Artery Endothelial Cell Redox State and NADPH Generation by Methylglyoxal.

Authors :
Morgan, Philip E.
Sheahan, Pamela J.
Davies, Michael J.
Source :
PLoS ONE; Jan2014, Vol. 9 Issue 1, p1-11, 11p
Publication Year :
2014

Abstract

Diabetes is associated with elevated plasma glucose, increased reactive aldehyde formation, oxidative damage, and glycation/glycoxidation of biomolecules. Cellular detoxification of, or protection against, such modifications commonly requires NADPH-dependent reducing equivalents (e.g. GSH). We hypothesised that reactive aldehydes may modulate cellular redox status via the inhibition of NADPH-generating enzymes, resulting in decreased thiol and NADPH levels. Primary human coronary artery endothelial cells (HCAEC) were incubated with high glucose (25 mM, 24 h, 37°C), or methylglyoxal (MGO), glyoxal, or glycolaldehyde (100–500 µM, 1 h, 37°C), before quantification of intracellular thiols and NADPH-generating enzyme activities. Exposure to MGO, but not the other species examined, significantly (P<0.05) decreased total thiols (∼35%), further experiments with MGO showed significant losses of GSH (∼40%) and NADPH (∼10%); these changes did not result in an immediate loss of cell viability. Significantly decreased (∼10%) NADPH-producing enzyme activity was observed for HCAEC when glucose-6-phosphate or 2-deoxyglucose-6-phosphate were used as substrates. Cell lysate experiments showed significant MGO-dose dependent inhibition of glucose-6-phosphate-dependent enzymes and isocitrate dehydrogenase, but not malic enzyme. Analysis of intact cell or lysate proteins showed that arginine-derived hydroimidazolones were the predominant advanced glycation end-product (AGE) formed; lower levels of N<superscript>ε</superscript>-(carboxyethyl)lysine (CEL) and N<superscript>ε</superscript>-(carboxymethyl)lysine (CML) were also detected. These data support a novel mechanism by which MGO exposure results in changes in redox status in human coronary artery endothelial cells, via inhibition of NADPH-generating enzymes, with resultant changes in reduced protein thiol and GSH levels. These changes may contribute to the endothelial cell dysfunction observed in diabetes-associated atherosclerosis. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
19326203
Volume :
9
Issue :
1
Database :
Complementary Index
Journal :
PLoS ONE
Publication Type :
Academic Journal
Accession number :
94235517
Full Text :
https://doi.org/10.1371/journal.pone.0086564