title: Arsenite Acutely Decreases Nitric Oxide Production via the ROS-Protein Phosphatase 1-Endothelial Nitric Oxide Synthase-Thr(497) Signaling Cascade.
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-Ser(1179) 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-Thr(497), but not of eNOS-Ser(116) or eNOS-Ser(1179), 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-Thr(497) phosphorylation. Although protein kinase C (PKC) and protein phosphatase 1 (PP1) were reported to be involved in eNOS-Thr(497) phosphorylation, treatment with PKC inhibitor, Ro318425, and overexpression of various PKC isoforms did not affect the arsenite-stimulated eNOS-Thr(497) phosphorylation. In contrast, treatment with PP1 inhibitor, calyculin A, mimicked the observed effect of arsenite on eNOS-Thr(497) 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-Thr(497) phosphorylation via ROS-PP1 signaling pathway, which provide the molecular mechanism underlying arsenite-induced increase in vascular disease.
authors.affiliation: Department of Molecular Medicine, School of Medicine, Ewha Womans University, Seoul 158-710 ; Institute of Pharmaceutical Research and Development, College of Pharmacy, Wonkwang University, Iksan 570-749.
authors.forename: Jungwon
authors.initials: J
authors.lastname: Seo
authors.affiliation: Department of Molecular Medicine, School of Medicine, Ewha Womans University, Seoul 158-710.
authors.forename: Jee Young
authors.initials: JY
authors.lastname: Lee
authors.affiliation: Department of Molecular Medicine, School of Medicine, Ewha Womans University, Seoul 158-710.
authors.forename: Min-Sun
authors.initials: MS
authors.lastname: Sung
authors.affiliation: Department of Molecular Medicine, School of Medicine, Ewha Womans University, Seoul 158-710.
authors.forename: Catherine Jeonghae
authors.initials: CJ
authors.lastname: Byun
authors.affiliation: Department of Pharmacology, School of Medicine, Eulji University, Daejeon 301-768.
authors.forename: Du-Hyong
authors.initials: DH
authors.lastname: Cho
authors.affiliation: Department of Molecular Medicine, School of Medicine, Ewha Womans University, Seoul 158-710.
authors.forename: Hyeon-Ju
authors.initials: HJ
authors.lastname: Lee
authors.affiliation: Department of Molecular Medicine, School of Medicine, Ewha Womans University, Seoul 158-710.
authors.forename: Jung-Hyun
authors.initials: JH
authors.lastname: Park
authors.affiliation: Biosafety Research Institute and College of Veterinary Medicine, Chonbuk National University, Jeonju 561-756.
authors.forename: Ho-Seong
authors.initials: HS
authors.lastname: Cho
authors.affiliation: Department of Biology, College of Natural Sciences, Chungbuk National University, Cheongju 362-763, Republic of Korea.
authors.forename: Sung-Jin
authors.initials: SJ
authors.lastname: Cho
authors.affiliation: Department of Molecular Medicine, School of Medicine, Ewha Womans University, Seoul 158-710.
authors.forename: Inho
authors.initials: I
authors.lastname: Jo
keywords: Arsenite; Endothelial nitric oxide synthase; Nitric oxide; Protein phosphatase 1; Reactive oxygen species; Vascular disease