Inhibition of PARP prevents oxidant-induced necrosis but not apoptosis in LLC-PK₁cells

Abstract

Oxidant-induced cell injury has been implicated in the pathogenesis of several forms of acute renal failure. The present studies examined whether activation of poly(ADP-ribose)polymerase (PARP) by oxidant-induced DNA damage contributes to oxidant injury of renal epithelial cells. H2O2exposure resulted in an increase in PARP activity and decreases in cell ATP and NAD content. These changes were significantly inhibited by 10 mM 3-aminobenzamide (3-ABA), a PARP inhibitor. In contrast, H2O2-induced DNA damage was not prevented by 3-ABA. Exposure of LLC-PK1 cells to 1 mM H2O2for 2 h induced necrotic cell death as measured by increased lactate dehydrogenase (LDH) release. 3-ABA completely prevented the H2O2-induced LDH release. Live/dead fluorescent staining confirmed the protection by 3-ABA. These results are consistent with the view that oxidant-induced DNA damage activates PARP and that the subsequent ATP and NAD depletion contribute to necrotic cell death. Of note, although protected from necrosis, cells treated with H2O2and 3-ABA underwent apoptosis as evidenced by DNA fragmentation and bis-benzimide staining. In conclusion, activation of PARP contributes to oxidant-induced ATP depletion and necrosis in LLC-PK1 cells. However, PARP inhibition may target cells toward an apoptotic form of cell death.

Cell death induced by acute renal injury: a perspective on the contributions of apoptosis and necrosis

“…The mechanisms by which ROS induce damage to the cells include peroxidation of lipid membranes, protein denaturation, and DNA strand breaks (34). The massive DNA damage associated with renal ischemia leads to excessive activation of the DNA repair enzyme PARP (64,140) and subsequent ATP depletion (72,253).…”

Activation of the transient receptor potential M2 channel and poly(ADP-ribose) polymerase is involved in oxidative stress-induced cardiomyocyte death

“…Prevention of H 2 O 2 -induced NAD þ depletion by PARP inhibitors has also been demonstrated in other studies. 28,29 After treatment with DNA-damaging reagents (e.g. H 2 O 2 ), the enzyme poly(ADP-ribose) glycohydrolase (PARG) converts PAR (half-life of less than 1 min) into mono(-ADPR).…”

Pharmacological profile of KR-33028, a highly selective inhibitor of Na+/H+ exchanger

“…To define the effects of KR-33028 on hypoxia-induced cell death, the activity of LDH released from H9c2 cells during hypoxia was measured, as an indicator of necrotic cell death (Koh and Choi, 1987;Filipovic et al, 1999). As shown in Fig.…”