Inhibiting long chain fatty Acyl CoA synthetase increases basal and agonist-stimulated NO synthesis in endothelium.
OBJECTIVE
Endothelial nitric oxide synthase (eNOS) activation/deactivation is associated with cyclic depalmitoylation/repalmitoylation of specific Cys residues. The mechanism of depalmitoylation has been identified recently, but repalmitoylation remains undefined. We hypothesized that long chain fatty acyl CoA synthetase (LCFACoAS) modulates endothelial nitric oxide synthase repalmitoylation by limiting palmitoyl CoA availability.


METHODS
Human coronary endothelial cells were treated with triacsin-C, an inhibitor of long chain fatty acyl CoA synthetase, for 24 h. Media nitrite accumulation, eNOS activity, and eNOS palmitoylation were measured. Methacholine-induced NO synthesis or vascular relaxation were measured in endothelium-intact rat aortae in the presence and absence of triacsin-C.


RESULTS
Triacsin-C significantly reduced incorporation of [3H] palmitate into immunoreactive endothelial nitric oxide synthase and over a concentration range of 0.1 to 10 microM, increased media nitrite accumulations 2- to 2.5-fold over baseline. Total in vitro catalytic activity of nitric oxide synthase in triacsin-C treated cells did not differ significantly from control. Triacsin-C significantly increased methacholine-induced NO synthesis in the isolated rat aorta, and significantly enhanced methacholine-induced relaxation of rat aortic rings.


CONCLUSIONS
These data are consistent with the interpretation that inhibition of palmitoylation increases endothelial nitric oxide synthase activity without changing endothelial nitric oxide synthase expression, suggesting that inhibiting palmitoylation increases the catalytically active fraction of endothelial nitric oxide synthase.
Weis
Margaret T
MT
Department of Pharmaceutical Sciences, Texas Tech University Health Science Center, 1300 Coulter, Amarillo, TX 79106, USA. margaret.weis@tuuhsc.edu
Crumley
Jason L
JL
Young
Lindon H
LH
Stallone
John N
JN
D000818:Animals; D002478:Cells, Cultured; D002794:Choline / Q000031:analogs & derivatives* / Q000494:pharmacology; D003066:Coenzyme A Ligases / Q000037:antagonists & inhibitors*; D003331:Coronary Vessels; D003593:Cytoplasm / Q000201:enzymology; D042783:Endothelial Cells / Q000378:metabolism; D004730:Endothelium, Vascular / Q000378:metabolism*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000378:metabolism*; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III; D009573:Nitrites / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014226:Triazenes / Q000494:pharmacology*
D009573:Nitrites; D014226:Triazenes; C017506:methylcholine; D009569:Nitric Oxide; C034613:triacsin C; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D003066:Coenzyme A Ligases; D002794:Choline