Vanadyl sulfate inhibits NO production via threonine phosphorylation of eNOS.

Abstract

Exposure to excessive vanadium occurs in some occupations and with consumption of some dietary regimens for weight reduction and body building. Because vanadium is vasoactive, individuals exposed to excessive vanadium may develop adverse vascular effects. We have previously shown that vanadyl sulfate causes acute pulmonary vasoconstriction, which could be attributed in part to inhibition of nitric oxide production. In the present study we investigated whether NO inhibition was related to phosphorylation of endothelial nitric oxide synthase (eNOS). VOSO 4 produced dose-dependent constriction of pulmonary arteries in isolated perfused lungs and pulmonary arterial rings and a right shift of the acetylcholine-dependent vasorelaxation curve. VOSO 4 inhibited constitutive as well as A23187-stimulated NO production. Constitutive NO inhibition was accompanied by increased Thr 495 (threonine at codon 495) phosphorylation of eNOS, which would inhibit eNOS activity. Thr 495 phosphorylation of eNOS and inhibition of NO were partially reversed by pretreatment with calphostin C, a protein kinase C (PKC) inhibitor. There were no changes in Ser 1177 (serine at codon 1177) or tyrosine phosphorylation of eNOS. These results indicate that VOSO 4 induced acute pulmonary vasoconstriction that was mediated in part by the inhibition of endothelial NO production via PKC-dependent phosphorylation of Thr 495 of eNOS. Exposure to excessive vanadium may contribute to pulmonary vascular diseases.

Anandamide-Mediated CB1/CB2Cannabinoid Receptor-Independent Nitric Oxide Production in Rabbit Aortic Endothelial Cells

“…Our evidence that (R)-methanandamide produced an Akt-mediated phosphorylation at Ser 1177 is in agreement with the results reported by Sessa and colleagues in bovine aortic endothelial cells stimulated with sphingosine-1-phosphate (Igarashi and Michel, 2001;Lin et al, 2003). Protein kinase C signaling acts in opposition by phosphorylating Thr 495 residues and promoting phosphatase-mediated Ser 1177 dephosphorylation (Li et al, 2004). Our data are consistent with eNOS activation via a PI3-kinase-Akt pathway that involves a mechanism requiring G i activation.…”

Pollutant particles enhanced H2O2 production from NAD(P)H oxidase and mitochondria in human pulmonary artery endothelial cells

“…H 2 O 2 produced by NAD(P)H oxidase contributed to PMinduced vasoconstriction because DPI inhibited UP-induced constriction of PA ring and intravascular administration of extracellular H 2 O 2 produced by glucose and glucose oxidase produced acute vasoconstriction in perfused lungs. We and others have previously identified several signaling pathways that mediate PM-induced vasoconstriction, including epidermal growth factor receptor, angiotensin II receptor subtype 1, endothelins, and NO (8,25,27,31,32,44). Our results indicate that H 2 O 2 produced by the membrane NAD(P)H oxidase should also be added to the list.…”

Opposite Effect of Hsp90αand Hsp90β on eNOS Ability to Produce Nitric Oxide or Superoxide Anion in Human Embryonic Kidney Cells

“…In this regard, we have recently shown that Hsp90 inhibition with radicicol, that reduced Hsp90 interaction with their client proteins, produced a significant reduction in renal plasma flow and glomerular filtration rate, an effect that was associated with a decreased urinary excretion of nitrites and nitrates (NO 2 /NO 3 ), suggesting that the disruption of eNOS-Hsp90 complex reduced renal NO synthesis [20]. In addition, previous studies have shown that the disruption of eNOS/Hsp90 complex promotes not only the reduction anion by eNOS [8,9,21,22]. Even though there is enough evidence about the Hsp90/eNOS coupling and uncoupling in NO and O 2 -generation, respectively, the specific role of Hsp90α and Hsp90β in this pathway have not been completely addressed.…”