title: Fluvastatin upregulates endothelial nitric oxide synthase activity via enhancement of its phosphorylation and expression and via an increase in tetrahydrobiopterin in vascular endothelial cells.
abstract: BACKGROUND
  An HMG-CoA reductase inhibitor, fluvastatin, appears to act directly on the blood vessel wall to stabilize plaques in situ, agents that share this property have been termed vascular statins.
  
  
  METHODS
  We investigated the effects of fluvastatin on endothelial nitric oxide synthase (eNOS) phosphorylation and expression, as well as terahydrobiopterin (BH4) metabolism, in human umbilical vein endothelial cells (HUVEC).
  
  
  RESULTS
  Fluvastatin was observed to enhance eNOS phosphorylation at Ser-1177 and Ser-633 through the PI3-kinase/Akt and PKA pathways, respectively. Inhibition of eNOS phosphorylation using inhibitors of these pathways attenuated acute NO release in response to fluvastatin. The mRNA of GTP cyclohydrolase I (GTPCH), the rate-limiting enzyme of the first step of de novo BH4 synthesis, as well as eNOS, was upregulated in HUVEC treated with fluvastatin. In parallel with this observation, fluvastatin increased intracellular BH4. Pre-treatment of HUVEC with the selective GTPCH inhibitor, 2,4-diamino-6-hydroxypyrimidine, reduced intracellular BH4 and decreased citrulline formation following stimulation with ionomycin. Furthermore, the potentiating effect of fluvastatin was reduced by limiting the cellular availability of BH4.
  
  
  CONCLUSIONS
  Our data demonstrate that fluvastatin phosphorylates and activates eNOS, and increases eNOS expression in vascular endothelial cells. In addition to modulating eNOS, fluvastatin potentiates GTPCH gene expression and BH4 synthesis, thereby increasing NO production and preventing relative shortages of BH4.
authors.affiliation: Department of Endocrinology and Metabolism, Dokkyo University School of Medicine, Mibu, Tochigi 321-0293, Japan.
authors.forename: Chie
authors.initials: C
authors.lastname: Aoki
authors.forename: Ayuko
authors.initials: A
authors.lastname: Nakano
authors.forename: Seiichi
authors.initials: S
authors.lastname: Tanaka
authors.forename: Kazunori
authors.initials: K
authors.lastname: Yanagi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ohta
authors.forename: Teruo
authors.initials: T
authors.lastname: Jojima
authors.forename: Kikuo
authors.initials: K
authors.lastname: Kasai
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Takekawa
authors.forename: Koichi
authors.initials: K
authors.lastname: Hirata
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Hattori
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001708:Biopterins / Q000031:analogs & derivatives* / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology; D004789:Enzyme Activation; D005229:Fatty Acids, Monounsaturated / Q000494:pharmacology*; D000077340:Fluvastatin; D005786:Gene Expression Regulation; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000201:enzymology*; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D051379:Mice; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D010766:Phosphorylation; D015854:Up-Regulation
chemical_list: D000975:Antioxidants; D005229:Fatty Acids, Monounsaturated; D007211:Indoles; D001708:Biopterins; D000077340:Fluvastatin; D052250:Nitric Oxide Synthase Type III; C003402:sapropterin