title: The role of poly(ADP-ribose) polymerase (PARP) in the autonomous proliferative response of endothelial cells to hypoxia.
abstract: OBJECTIVE
  The autonomous proliferative response of endothelial cells to hypoxia has been shown to be dependent on activation of NAD(P)H oxidase, on the cytosolic Ca2+ load, and, consequently, on nuclear translocation of extracellular signal-regulated kinase (ERK)1/2 during transient hypoxia. The aim of the present study was to investigate whether poly(ADP-ribose) polymerase (PARP) is a downstream signal of NAD(P)H oxidase, mediating cytosolic Ca2+ load and hence nuclear translocation of ERK1/2 and endothelial cell proliferation.
  
  
  METHODS
  Porcine aortic endothelial cells were incubated under hypoxic conditions for 40 min. Cytosolic [Ca2+] and reactive oxygen species (ROS) formation were measured in fura-2- and DCF-loaded cells, respectively. PARP activation was detected by immunocytochemistry, and endothelial cell proliferation was determined 24 h after 60 min of transient hypoxia.
  
  
  RESULTS
  Inhibition of NAD(P)H oxidase with antisense oligonucleotide against the p22(phox) subunit, MEK/ERK signalling with UO 126 (30 microM), or PARP with PJ 34 (10 microM) leads to a marked reduction in hypoxia-induced cytosolic Ca2+ load and activation of PARP. Hypoxia-induced translocation of ERK1/2 and endothelial cell proliferation were also prevented when NAD(P)H oxidase or PARP were inhibited; however, hypoxic ROS formation was not affected in the presence of PARP inhibitor.
  
  
  CONCLUSIONS
  PARP represents a downstream effector of NADP(H) oxidase and acts as a necessary intermediate step for the hypoxic proliferative response of endothelial cells.
authors.affiliation: Institute of Physiology, Justus-Liebig-University, D-35392 Giessen, Germany. Yaser.Abdallah@physiologie.med.uni-giessen.de
authors.forename: Yaser
authors.initials: Y
authors.lastname: Abdallah
authors.forename: Dragan
authors.initials: D
authors.lastname: Gligorievski
authors.forename: Sascha A
authors.initials: SA
authors.lastname: Kasseckert
authors.forename: Lukas
authors.initials: L
authors.lastname: Dieterich
authors.forename: Matthias
authors.initials: M
authors.lastname: Schäfer
authors.forename: Christoph R
authors.initials: CR
authors.lastname: Kuhlmann
authors.forename: Thomas
authors.initials: T
authors.lastname: Noll
authors.forename: Heinrich
authors.initials: H
authors.lastname: Sauer
authors.forename: H Michael
authors.initials: HM
authors.lastname: Piper
authors.forename: Claudia
authors.initials: C
authors.lastname: Schäfer
mesh_terms: D000818:Animals; D002070:Butadienes / Q000494:pharmacology; D002118:Calcium / Q000032:analysis / Q000378:metabolism; D015687:Cell Hypoxia / Q000502:physiology; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D003600:Cytosol / Q000737:chemistry / Q000378:metabolism; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D004730:Endothelium, Vascular; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000032:analysis / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D007150:Immunohistochemistry; D020935:MAP Kinase Signaling System; D008856:Microscopy, Fluorescence; D019255:NADPH Oxidases / Q000235:genetics; D009570:Nitriles / Q000494:pharmacology; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D010616:Phenanthrenes / Q000494:pharmacology; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013552:Swine
chemical_list: D002070:Butadienes; C434926:N-(oxo-5,6-dihydrophenanthridin-2-yl)-N,N-dimethylacetamide hydrochloride; D009570:Nitriles; D016376:Oligonucleotides, Antisense; D010616:Phenanthrenes; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D017382:Reactive Oxygen Species; C113580:U 0126; D006861:Hydrogen Peroxide; D019255:NADPH Oxidases; C086986:CYBA protein, human; D011065:Poly(ADP-ribose) Polymerases; D048049:Extracellular Signal-Regulated MAP Kinases; D002118:Calcium