Peroxisome Proliferator-Activated Receptor γ Ligands Stimulate Endothelial Nitric Oxide Production Through Distinct Peroxisome Proliferator-Activated Receptor γ–Dependent Mechanisms

Abstract

Objective-We recently reported that the peroxisome proliferator-activated receptor ␥ (PPAR␥) ligands 15-deoxy-⌬ 12,14 -prostaglandin J 2 (15d-PGJ 2 ) and ciglitazone increased cultured endothelial cell nitric oxide (NO) release without increasing the expression of endothelial nitric oxide synthase (eNOS). The current study was designed to characterize further the molecular mechanisms underlying PPAR␥-ligand-stimulated increases in endothelial cell NO production. Methods and Results-Treating human umbilical vein endothelial cells (HUVEC) with PPAR␥ ligands (10 mol/L 15d-PGJ 2 , ciglitazone, or rosiglitazone) for 24 hours increased NOS activity and NO release. In selected studies, HUVEC were treated with PPAR␥ ligands and with the PPAR␥ antagonist GW9662 (2 mol/L), which fully inhibited stimulation of a luciferase reporter gene, or with small interfering RNA to PPAR␥, which reduced HUVEC PPAR␥ expression. Treatment with either small interfering RNA to PPAR␥ or GW9662 inhibited 15d-PGJ 2 -, ciglitazone-, and rosiglitazone-induced increases in endothelial cell NO release. Rosiglitazone and 15d-PGJ 2 , but not ciglitazone, increased heat shock protein 90-eNOS interaction and eNOS ser 1177 phosphorylation. The heat shock protein 90 inhibitor geldanamycin attenuated 15d-PGJ 2 -and rosiglitazone-stimulated NOS activity and NO production. Key Words: peroxisome proliferator-activated receptor ␥ Ⅲ nitric oxide Ⅲ endothelium Ⅲ endothelial nitric oxide synthase Ⅲ thiazolidinedione E ndothelium-derived nitric oxide (NO) is a key molecule in vascular biology that decreases vascular tone, smooth muscle cell proliferation, leukocyte adhesion, and platelet aggregation. [1][2][3][4][5][6] Endothelial dysfunction, characterized by impaired endothelial NO production, participates in the pathogenesis of atherosclerotic disease and is associated with risk factors for vascular disease, including hypercholesterolemia, diabetes mellitus, insulin resistance, and obesity. 7 Our recent studies demonstrate that the peroxisome proliferator-activated receptor ␥ (PPAR␥) ligands 15-deoxy-⌬ 12,14 -PG J 2 (15d-PGJ 2 ) and ciglitazone stimulate NO release from endothelial cells (ECs). 8 Understanding the mechanisms of PPAR␥ ligand-induced stimulation of EC NO release may provide novel insights into the vascular protective effects of PPAR␥ ligands.In ECs, type III endothelial nitric oxide synthase (eNOS) produces NO from the amino acid L-arginine. eNOS is regulated not only at the level of expression, 9 -11 but also post-translationally by mechanisms including interactions of eNOS with other proteins 12-15 and eNOS phosphorylation. 16 -19 For example, specific stimuli including vascular endothelial growth factor (VEGF), histamine, and shear stress have been shown to activate eNOS by promoting the interaction of eNOS with heat shock protein 90 (hsp90), a molecular chaperone protein. 14 Hsp90 has been shown to increase eNOS activity by (1) recruiting Akt, the serine protein kinase B, to phosphorylate eNOS at ser 1177 , 20 (2) facilitating the displa...

Nifedipine Activates PPARγ and Exerts Antioxidative Action Through Cu/ZnSOD Independent of Blood-pressure Lowering in SHRSP

“…In the present study, eNOS expression was unaffected by nifedipine in the SHRSP heart with or without GW9662. It has also been reported that PPAR agonists stimulate NO release through a mechanism related to NO production 42) but unrelated to eNOS expression 43) , and decrease NAD(P)H oxidase-dependent ·O2 production 41) . Although in the present study, circulating concentrations of NO metabolites were not measured, they may follow a similar pattern to the relaxant responses in SHRSP groups.…”

A PKG inhibitor increases Ca2+-regulated exocytosis in guinea pig antral mucous cells: cAMP accumulation via PDE2A inhibition

“…Some reports have shown that AA and PPARs stimulate NO production in many tissues and cells (7,13,15,19,21,22). AA has been reported to stimulate cGMP accumulation via NO production in vascular smooth muscle cells (9).…”

Effect of Telmisartan on Nitric Oxide–Asymmetrical Dimethylarginine System

“…This effect appears to be independent of its AT 1 R blocking actions. 19 PPAR␥ signaling has important antiatherogenic properties 20 and is associated with decreased oxidative stress 21 and increased NO formation, 22 which are 2 of the most important component affecting the process of aging in ECs. [2][3][4][5]11,12 On the basis of these observations, we examined the effect of telmisartan on oxidative stress as well as ADMA-NO pathway through AT 1 R or PPAR␥ signaling during aging of ECs.…”