Original Paper

Poly(ADP-Ribose) Polymerase Offers Protection against Oxidative and Alkylation Damage to the Nuclear and Mitochondrial Genomes of the Retinal Pigment Epithelium
Stuart G. Jarrett^a, Michael E. Boulton<sup>b

a</sup>Cell and Molecular Biology Unit, School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK;
^bDepartment of Ophthalmology and Visual Sciences, The University of Texas Medical Branch, Galveston, Tex., USA

Address of Corresponding Author

Ophthalmic Res 2007;39:213-223 (DOI: 10.1159/000104683)

  Key Words

• Oxidative stress
• Oxidative DNA damage
• DNA repair
• Poly(ADP-ribose)polymerase

  Abstract

Purpose: To investigate the role of poly(ADP-ribose)-polymerase (PARP) in protecting against oxidative (H₂O₂) and alkylation (MMS) damage to the nDNA and mtDNA genomes of the retinal pigment epithelium (RPE). We further hypothesized that PARP ribosylation enzymatic activity is required to facilitate efficient nDNA and mtDNA repair to enable the RPE to survive chronic oxidative stress exposure. Methods: Cellular sensitivity to H₂O₂ and MMS was determined by the MTT and LDH assays. PARP ribosyl(ation) activity was inhibited by supplementation of 3-aminobenzamide (competitive PARP inhibitor). The susceptibility and repair capacities of nuclear and mitochondrial genomes were assessed by quantitative PCR and PARP activity assessed using an enzyme assay. Results: This study demonstrated that cells lacking ribosyl(ation) activity had a significantly lower lesion repair capacity in both nDNA and mtDNA (p < 0.05), which culminated in reduced cell viability after H₂O₂ exposure only (p < 0.05). Furthermore, the mtDNA demonstrated a significantly greater sensitivity compared to nDNA to both oxidative and alkylation damage (p < 0.05). Conclusion: PARP activity has an important role in providing the RPE with the high oxidative tolerance required for this cell type to survive the constant reactive oxygen species attack in vivo for several decades.

Copyright © 2007 S. Karger AG, Basel

  Author Contacts

Prof. Mike Boulton, Director of AMD Center
Department of Ophthalmology and Visual Sciences
301 University Boulevard
Galveston, TX 77555-1106 (USA)
Tel. +1 409 772 8002, Fax +1 409 772 8018, E-Mail meboulto@utmb.edu

  Article Information

Received: September 12, 2006
Accepted after revision: February 26, 2007
Published online: June 26, 2007
Number of Print Pages : 11
Number of Figures : 7, Number of Tables : 0, Number of References : 44