Regulation of Endothelial Nitric Oxide Synthase Expression in the Vascular Wall and in Mononuclear Cells From Hypercholesterolemic Rabbits

Abstract

Background-We recently obtained evidence demonstrating that cultured bovine endothelial cells contain cytosolic proteins that form complexes with the 3Ј-untranslated region of endothelial nitric oxide synthase (eNOS) mRNA and are associated with its destabilization. The aim of this study was to determine the presence of such proteins and eNOS expression in hypercholesterolemic rabbits as an in vivo model of endothelial dysfunction. Methods and Results-Endothelium-dependent relaxation to acetylcholine and the calcium ionophore A23187 was reduced in aortic segments from hypercholesterolemic rabbits compared with controls. Treatment of hypercholesterolemic rabbits with cerivastatin (0.1 mg · kg body wt Ϫ1 · d Ϫ1 ) restored endothelium-dependent relaxation. Aortic eNOS expression was reduced in hypercholesterolemic rabbits and was accompanied by enhanced binding activity of a 60-kDa cytosolic protein and reduced stability of eNOS mRNA. Cerivastatin treatment upregulated eNOS expression and reduced the interaction of the cytosolic protein with the 3Ј-untranslated region of eNOS mRNA. Mononuclear cells from hypercholesterolemic rabbits also showed a marked reduction of eNOS expression and eNOS mRNA stability and an increase in binding activity of the cytosolic protein, which were also prevented by cerivastatin treatment.Conclusions-These results demonstrate the presence of a 60-kDa protein that binds to eNOS mRNA and reductions in eNOS expression in both vascular wall and mononuclear cells that are prevented by cerivastatin.

Aspirin Prevents Escherichia coli Lipopolysaccharide– and Staphylococcus aureus –Induced Downregulation of Endothelial Nitric Oxide Synthase Expression in Guinea Pig Pericardial Tissue

“…[8][9][10]25 In the present study, we have demonstrated that pericardial cytosolic lysates form complexes with the complete in vitrotranscribed 3Ј-UTR of eNOS mRNA. Furthermore, cytosolic lysates obtained from LPS-and SA-incubated pericardial samples showed an increased binding activity to 3Ј-UTR of eNOS mRNA, which was associated with a decreased level of eNOS protein and eNOS mRNA expression.…”

Modulation of Endothelium and Endothelial Progenitor Cell Function by Low-Density Lipoproteins: Implication for Vascular Repair, Angiogenesis and Vasculogenesis

“…Moreover, supplementation with L -arginine, the precursor of NO, reverses endothelial dysfunction in otherwise healthy young humans with hypercholesterolemia [22] . The reduction in NO bioavailability observed in hypercholesterolemic patients [23,24] could be related to various mechanisms, among them: (1) a decrease in endothelial NO synthase (eNOS) expression (mRNA and protein levels) in response to oxidized LDLs (oxLDLs) and atherogenic concentrations of native LDLs (nLDLs) has been described in vivo [25] and in vitro [13,14,17] ; (2) an increase in caveolin-1 and the inactive complex caveolin-1/eNOS, has been reported in endothelial cells treated with sera from hypercholesterolemic patients , has been observed ex vivo in vessels from hypercholesterolemic animals [27] ; (4) the uncoupling of eNOS activity produced by oxLDL and atherogenic concentrations of nLDLs that reduce the association between eNOS and hsp90 and increases the generation of O 2 -have been reported [28,29] ; (5) the reduction of eNOS activity as a consequence of the inhibitory effect of asymmetric dimethylarginine (ADMA), whose levels are increased in hypercholesterolemic patients [30] or (6) the impairment of L -arginine uptake by endothelial cells produced by both nLDLs and oxLDLs [29] .…”

Aterosclerose experimental em coelhos

“…Considering hyperlipidemia and atherosclerosis, aortic segments of hypercholesterolemic rabbits show significant reduction of endothelial nitric oxide synthase (NOS) in relation to controls 17 . Vasquez-Vivar et al 18 reported that BH4, a cofactor for the synthesis of NO in the aorta of rabbits fed a hypercholesterolemia-inducing diet, was markedly reduced in comparison to normocholesterolemic rabbits.…”