title: Cellular bioenergetics is regulated by PARP1 under resting conditions and during oxidative stress.
abstract: OBJECTIVE
  The goal of the current studies was to elucidate the role of the principal poly(ADP-ribose)polymerase isoform, PARP1 in the regulation of cellular energetics in endothelial cells under resting conditions and during oxidative stress.
  
  
  METHODS
  We utilized bEnd.3 endothelial cells and A549 human transformed epithelial cells. PARP1 was inhibited either by pharmacological inhibitors or by siRNA silencing. The Seahorse XF24 Extracellular Flux Analyzer was used to measure indices of mitochondrial respiration (oxygen consumption rate) and of glycolysis (extracellular acidification rate). Cell viability, cellular and mitochondrial NAD(+) levels and mitochondrial biogenesis were also measured.
  
  
  RESULTS
  Silencing of PARP1 increased basal cellular parameters of oxidative phosphorylation, providing direct evidence that PARP1 is a regulator of mitochondrial function in resting cells. Pharmacological inhibitors of PARP1 and siRNA silencing of PARP1 protected against the development of mitochondrial dysfunction and elevated the respiratory reserve capacity in endothelial and epithelial cells exposed to oxidative stress. The observed effects were unrelated to an effect on mitochondrial biogenesis. Isolated mitochondria of A549 human transformed epithelial cells exhibited an improved resting bioenergetic status after stable lentiviral silencing of PARP1; these effects were associated with elevated resting mitochondrial NAD+ levels in PARP1 silenced cells.
  
  
  CONCLUSIONS
  PARP1 is a regulator of basal cellular energetics in resting endothelial and epithelial cells. Furthermore, endothelial cells respond with a decrease in their mitochondrial reserve capacity during low-level oxidative stress, an effect, which is attenuated by PARP1 inhibition. While PARP1 is a regulator of oxidative phosphorylation in resting and oxidatively stressed cells, it only exerts a minor effect on glycolysis.
authors.affiliation: Department of Anesthesiology, The University of Texas Medical Branch, Galveston, TX 77555, USA.
authors.forename: Katalin
authors.initials: K
authors.lastname: Módis
authors.forename: Domokos
authors.initials: D
authors.lastname: Gero
authors.forename: Katalin
authors.initials: K
authors.lastname: Erdélyi
authors.forename: Petra
authors.initials: P
authors.lastname: Szoleczky
authors.forename: Douglas
authors.initials: D
authors.lastname: DeWitt
authors.forename: Csaba
authors.initials: C
authors.lastname: Szabo
mesh_terms: D002460:Cell Line; D042783:Endothelial Cells / Q000378:metabolism*; D004734:Energy Metabolism / Q000502:physiology; D006801:Humans; D008928:Mitochondria / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology*; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering
chemical_list: D034741:RNA, Small Interfering; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases