Figure 1.

Knockdown of PARG and PARP1 in A549 cells. A, B) Following transduction with control (CTL), PARP1-specific and PARG-specific shRNA-knockdown efficiency on gene expression were determined by PCR and real-time quantitative PCR; β-actin was used as the invariant control. Significant drops in PARP1 and PARG mRNA were observed (B). C) Western blot analysis of whole-protein extracts from nontransduced A549 cells, cells infected with control viruses, shPARP1 cells, and shPARG cells. Immunoblotting was performed with the anti-PARP1 antibody; the anti-actin antibody as a loading control. D) PARP activity was determined by ³H-NAD incorporation in unstimulated and 400 μM hydrogen peroxide-treated cells. shPARP-1 cells exhibited significantly lower basal PARP activity. Hydrogen peroxide induced PARP activation. PARP activation was significantly lower in shPARP1 and, to a lesser extent, in shPARG cells. *P < 0.05; **P < 0.01; ***P < 0.001.