title: Role of transient receptor potential vanilloid 1 in regulating erythropoietin-induced activation of endothelial nitric oxide synthase.
abstract: Erythropoietin (EPO), the key hormone involved in erythropoiesis, beneficially affects endothelial cells (ECs), but the detailed mechanisms are yet to be completely understood. In this study, we investigated the role of transient receptor potential vanilloid type 1 (TRPV1), a ligand-gated non-selective calcium (Ca2+) channel, in EPO-mediated endothelial nitric oxide synthase (eNOS) activation and angiogenesis.
  
  
  
  In ECs, EPO time dependently increased intracellular levels of calcium; this increase was abrogated by the Ca2+chelators and pharmacological inhibitors of TRPV1 in bovine aortic ECs (BAECs) and TRPV1-transfected HEK293 cells. In addition, EPO-induced nitrite oxide (NO) production, phosphorylation of eNOS, Akt and AMP-activated protein kinase (AMPK) and the formation of TRPV1-Akt-AMPK-eNOS complex as well as tube formation were diminished by the pharmacological inhibition of TRPV1 in BAECs. Moreover, EPO time dependently induced the phosphorylation of phospholipase C-γ1 (PLC-γ1). Inhibition of PLC-γ1 activity blunted the EPO-induced Ca2+influx, eNOS phosphorylation, TRPV1-eNOS complex formation and NO production. The phosphorylated level of eNOS increased in the aortas of EPO-treated wild-type (WT) mice or EPO-transgenic (Tg) mice but not in those of EPO-treated TRPV1-deficient (TRPV1-/-) mice or EPO-Tg/TRPV1-/-mice. Matrigel plug assay showed that EPO-induced angiogenesis was abrogated in TRPV1 antagonist capsazepine-treated WT mice and TRPV1-/-mice.
  
  
  
  These findings indicate the EPO-induced Ca2+influx via the activation of the PLC-γ1 signalling pathway, which leads to TRPV1 activation and consequently increases the association of the TRPV1-Akt-AMPK-eNOS complex, eNOS activation, NO production and angiogenesis.
authors.affiliation: Institute of Physiology, National Yang-Ming University, Taipei, Taiwan.|Division of Hematology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Y-B
authors.initials: YB
authors.lastname: Yu
authors.affiliation: Institute of Physiology, National Yang-Ming University, Taipei, Taiwan.|The Jackson Laboratory, Bar Harbor, ME, USA.
authors.forename: K-H
authors.initials: KH
authors.lastname: Su
authors.affiliation: Institute of Physiology, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Y R
authors.initials: YR
authors.lastname: Kou
authors.affiliation: Institute of Physiology, National Yang-Ming University, Taipei, Taiwan.
authors.forename: B-C
authors.initials: BC
authors.lastname: Guo
authors.affiliation: Institute of Physiology, National Yang-Ming University, Taipei, Taiwan.
authors.forename: K-I
authors.initials: KI
authors.lastname: Lee
authors.affiliation: Heart Center, Cheng-Hsin General Hospital, Taipei, Taiwan.
authors.forename: J
authors.initials: J
authors.lastname: Wei
authors.affiliation: Institute of Physiology, National Yang-Ming University, Taipei, Taiwan.|Genome Research Center, National Yang-Ming University, Taipei, Taiwan.|Aging and Health Research Center, National Yang-Ming University, Taipei, Taiwan.
authors.forename: T-S
authors.initials: TS
authors.lastname: Lee
mesh_terms: D000818:Animals; D002417:Cattle; D042783:Endothelial Cells / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology*; D004921:Erythropoietin / Q000378:metabolism* / Q000494:pharmacology; D057809:HEK293 Cells; D006801:Humans; D047468:Immunoprecipitation; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D018919:Neovascularization, Physiologic / Q000502:physiology*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D050916:TRPV Cation Channels / Q000378:metabolism*
chemical_list: D050916:TRPV Cation Channels; C493921:TRPV1 protein, mouse; D004921:Erythropoietin; D052250:Nitric Oxide Synthase Type III
keywords: 
  eNOS
  ; Ca2+; TRPV1; angiogenesis; erythropoietin