Folic acid modulates eNOS activity via effects on posttranslational modifications and protein–protein interactions

Taylor, Sarah Yvonne, Dixon, Hannah M., Yoganayagam, Shobana, Price, Natalie and Lang, Derek 2013. Folic acid modulates eNOS activity via effects on posttranslational modifications and protein–protein interactions. European Journal of Pharmacology 714 (1-3) , pp. 193-201. 10.1016/j.ejphar.2013.05.026

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Abstract

Folic acid enhances endothelial function and improves outcome in primary prevention of cardiovascular disease. The exact intracellular signalling mechanisms involved remain elusive and were therefore the subject of this study. Particular focus was placed on folic acid-induced changes in posttranslational modifications of endothelial nitric oxide synthase (eNOS). Cultured endothelial cells were exposed to folic acid in the absence or presence of phosphatidylinositol-3' kinase/Akt (PI3K/Akt) inhibitors. The phosphorylation status of eNOS was determined via western blotting. The activities of eNOS and PI3K/Akt were evaluated. The interaction of eNOS with caveolin-1, Heat-Shock Protein 90 and calmodulin was studied using co-immunoprecipitation. Intracellular localisation of eNOS was investigated using sucrose gradient centrifugation and confocal microscopy. Folic acid promoted eNOS dephosphorylation at negative regulatory sites, and increased phosphorylation at positive regulatory sites. Modulation of phosphorylation status was concomitant with increased cGMP concentrations, and PI3K/Akt activity. Inhibition of PI3K/Akt revealed specific roles for this kinase pathway in folic acid-mediated eNOS phosphorylation. Regulatory protein and eNOS protein associations were altered in favour of a positive regulatory effect in the absence of bulk changes in intracellular eNOS localisation. Folic acid-mediated eNOS activation involves the modulation of eNOS phosphorylation status at multiple residues and positive changes in important protein–protein interactions. Such intracellular mechanisms may in part explain improvements in clinical vascular outcome following folic acid treatment.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Medicine
Subjects:	R Medicine > R Medicine (General)
Publisher:	Elsevier
ISSN:	0014-2999
Funders:	British Heart Foundation
Date of First Compliant Deposit:	30 March 2016
Date of Acceptance:	24 May 2013
Last Modified:	19 May 2023 13:10
URI:	https://orca.cardiff.ac.uk/id/eprint/62475

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