PARP-1 inhibition prevents oxidative and nitrosative stress-induced endothelial cell death via transactivation of the VEGF receptor 2.
OBJECTIVE
PARP-1, a DNA base repair enzyme, is activated by DNA breaks induced by oxidative (ROS) and nitrosative (RNS) stress. By consuming NAD(+), PARP-1 activation can lead to ATP depletion and cell death. Studies suggest that inhibiting PARP-1 activity can attenuate pathologies associated with vascular smooth muscle and endothelial dysfunction. PARP-1 inhibition can also activate the prosurvival serine/threonine kinase, Akt. Vascular endothelial growth factor (VEGF) regulates endothelial cell survival via Akt activation downstream of VEGF receptor 2 (VEGFR2) activation. Here we investigated the hypothesis that PARP-1 inhibition protects human umbilical vein endothelial cells (HUVECs) from ROS- and RNS-induced cell death by limiting NAD(+) depletion and by activating a prosurvival signaling pathway via VEGFR2 phosphorylation.


RESULTS
We activated PARP-1 in HUVECs by treatment with hydrogen peroxide (H(2)O(2)) and peroxynitrite (ONOO(-)). Both depleted HUVECs of NAD(+) and ATP, processes that were limited by the PARP-1 inhibitor, PJ34. ONOO(-) and H(2)O(2)-induced cell death and apoptosis were attenuated in cells treated with PJ34 or PARP-1 siRNA. PARP-1 inhibition increased Akt, BAD, and VEGFR2 phosphorylation in HUVECs and in PJ34-treated rabbit aortas. The VEGFR2-specific tyrosine kinase inhibitor SU1498 decreased PARP-1 inhibition-mediated phosphorylation of VEGFR2 and Akt, and also reversed survival effects of PJ34. Finally, PARP-1 inhibition protected cells from death induced by serum starvation, evidence for a role in cell survival independent of energy protection.


CONCLUSIONS
PARP-1 inhibition prevents ROS- and RNS-induced HUVEC death by maintaining cellular energy in the form of NAD(+) and ATP, and also by activating a survival pathway via VEGFR2, Akt, and BAD phosphorylation.
Mathews
Marlene T
MT
Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, 601 Elmwood Ave, Box 706, Rochester, New York 14642, USA.
Berk
Bradford C
BC
D000255:Adenosine Triphosphate / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D016923:Cell Death / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D002478:Cells, Cultured; D002934:Cinnamates / Q000494:pharmacology; D042783:Endothelial Cells / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D009243:NAD / Q000378:metabolism; D015538:Nitrosation; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010616:Phenanthrenes / Q000494:pharmacology; D000071137:Poly (ADP-Ribose) Polymerase-1; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D026361:Reactive Nitrogen Species / Q000378:metabolism; D015533:Transcriptional Activation; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000037:antagonists & inhibitors / Q000235:genetics*
D002934:Cinnamates; D004791:Enzyme Inhibitors; C434926:N-(oxo-5,6-dihydrophenanthridin-2-yl)-N,N-dimethylacetamide hydrochloride; D010616:Phenanthrenes; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D034741:RNA, Small Interfering; D026361:Reactive Nitrogen Species; C483044:SU 1498; D009243:NAD; D000255:Adenosine Triphosphate; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D040301:Vascular Endothelial Growth Factor Receptor-2