Biomol Ther.  2014 Nov;22(6):510-518. 10.4062/biomolther.2014.106.

Arsenite Acutely Decreases Nitric Oxide Production via the ROS-Protein Phosphatase 1-Endothelial Nitric Oxide Synthase-Thr497 Signaling Cascade

• Seo J
• Lee JY
• Sung MS
• Byun CJ
• Cho DH
• Lee HJ
• Park JH
• Cho HS
• Cho SJ
• Jo I

• KMID: 2170592
• DOI: http://doi.org/10.4062/biomolther.2014.106

Abstract

Chronic (>24 h) exposure of arsenite, an environmental toxicant, has shown the decreased nitric oxide (NO) production in endothelial cells (EC) by decreasing endothelial NO synthase (eNOS) expression and/or its phosphorylation at serine 1179 (eNOS-Ser1179 in bovine sequence), which is associated with increased risk of vascular diseases. Here, we investigated the acute (<24 h) effect of arsenite on NO production using bovine aortic EC (BAEC). Arsenite acutely increased the phosphorylation of eNOS-Thr497, but not of eNOS-Ser116 or eNOS-Ser1179, which was accompanied by decreased NO production. The level of eNOS expression was unaltered under this condition. Treatment with arsenite also induced reactive oxygen species (ROS) production, and pretreatment with a ROS scavenger N-acetyl-L-cysteine (NAC) completely reversed the observed effect of arsenite on eNOS-Thr497 phosphorylation. Although protein kinase C (PKC) and protein phosphatase 1 (PP1) were reported to be involved in eNOS-Thr497 phosphorylation, treatment with PKC inhibitor, Ro318425, and overexpression of various PKC isoforms did not affect the arsenite-stimulated eNOS-Thr497 phosphorylation. In contrast, treatment with PP1 inhibitor, calyculin A, mimicked the observed effect of arsenite on eNOS-Thr497 phosphorylation. Lastly, we found decreased cellular PP1 activity in arsenite-treated cells, which was reversed by NAC. Overall, our study demonstrates firstly that arsenite acutely decreases NO production at least in part by increasing eNOS-Thr497 phosphorylation via ROS-PP1 signaling pathway, which provide the molecular mechanism underlying arsenite-induced increase in vascular disease.

Keyword

Arsenite; Vascular disease; Nitric oxide; Endothelial nitric oxide synthase; Reactive oxygen species; Protein phosphatase 1

MeSH Terms

Acetylcysteine
Endothelial Cells
Nitric Oxide Synthase
Nitric Oxide Synthase Type III
Nitric Oxide*
Phosphorylation
Protein Isoforms
Protein Kinase C
Protein Phosphatase 1
Reactive Oxygen Species
Serine
Vascular Diseases
Acetylcysteine
Nitric Oxide
Nitric Oxide Synthase
Nitric Oxide Synthase Type III
Protein Isoforms
Protein Kinase C
Protein Phosphatase 1
Reactive Oxygen Species
Serine