Oxidative DNA damage in lung tissue from patients with COPD is clustered in functionally significant sequences

Int J Chron Obstruct Pulmon Dis. 2011;6:209-17. doi: 10.2147/COPD.S15922. Epub 2011 Mar 13.

Abstract

Lung tissue from COPD patients displays oxidative DNA damage. The present study determined whether oxidative DNA damage was randomly distributed or whether it was localized in specific sequences in either the nuclear or mitochondrial genomes. The DNA damage-specific histone, gamma-H2AX, was detected immunohistochemically in alveolar wall cells in lung tissue from COPD patients but not control subjects. A PCR-based method was used to search for oxidized purine base products in selected 200 bp sequences in promoters and coding regions of the VEGF, TGF-β1, HO-1, Egr1, and β-actin genes while quantitative Southern blot analysis was used to detect oxidative damage to the mitochondrial genome in lung tissue from control subjects and COPD patients. Among the nuclear genes examined, oxidative damage was detected in only 1 sequence in lung tissue from COPD patients: the hypoxic response element (HRE) of the VEGF promoter. The content of VEGF mRNA also was reduced in COPD lung tissue. Mitochondrial DNA content was unaltered in COPD lung tissue, but there was a substantial increase in mitochondrial DNA strand breaks and/or abasic sites. These findings show that oxidative DNA damage in COPD lungs is prominent in the HRE of the VEGF promoter and in the mitochondrial genome and raise the intriguing possibility that genome and sequence-specific oxidative DNA damage could contribute to transcriptional dysregulation and cell fate decisions in COPD.

Keywords: COPD; DNA damage; VEGF hypoxic response element; mtDNA.

Publication types

  • Multicenter Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analysis of Variance
  • Baltimore
  • Blotting, Southern
  • Case-Control Studies
  • Colorado
  • DNA Damage*
  • DNA, Mitochondrial / analysis
  • Histones / analysis
  • Humans
  • Immunohistochemistry
  • Lung / chemistry*
  • Lung / pathology
  • Oxidative Stress*
  • Polymerase Chain Reaction
  • Promoter Regions, Genetic
  • Pulmonary Disease, Chronic Obstructive / genetics*
  • Pulmonary Disease, Chronic Obstructive / metabolism
  • Pulmonary Disease, Chronic Obstructive / pathology
  • RNA, Messenger / analysis
  • Severity of Illness Index
  • Vascular Endothelial Growth Factor A / genetics

Substances

  • DNA, Mitochondrial
  • H2AX protein, human
  • Histones
  • RNA, Messenger
  • VEGFA protein, human
  • Vascular Endothelial Growth Factor A