Blue light induces mitochondrial DNA damage and free radical production in epithelial cells

Bernard F. Godley, Farrukh A. Shamsi, Fong Qi Liang, Stuart G. Jarrett, Sallyanne Davies, Mike Boulton

Research output: Contribution to journalArticle

236 Scopus citations

Abstract

Exposure of biological chromophores to ultraviolet radiation can lead to photochemical damage. However, the role of visible light, particularly in the blue region of the spectrum, has been largely ignored. To test the hypothesis that blue light is toxic to non-pigmented epithelial cells, confluent cultures of human primary retinal epithelial cells were exposed to visible light (390-550 nm at 2.8 milliwatts/cm2) for up to 6 h. A small loss of mitochondrial respiratory activity was observed at 6 h compared with dark-maintained cells, and this loss became greater with increasing time. To investigate the mechanism of cell loss, the damage to mitochondrial and nuclear genes was assessed using the quantitative PCR. Light exposure significantly damaged mitochondrial DNA at 3 h (0.7 lesion/10 kb DNA) compared with dark-maintained controls. However, by 6 h of light exposure, the number of lesions was decreased in the surviving cells, indicating DNA repair. Isolated mitochondria exposed to light generated singlet oxygen, superoxide anion, and the hydroxyl radical. Antioxidants confirmed the superoxide anion to be the primary species responsible for the mitochondrial DNA lesions. The effect of lipofuscin, a photoinducible intracellular generator of reactive oxygen intermediates, was investigated for comparison. Exposure of lipofuscin- containing cells to visible light caused an increase in both mitochondrial and nuclear DNA lesions compared with non-pigmented cells. We conclude that visible light can cause cell dysfunction through the action of reactive oxygen species on DNA and that this may contribute to cellular aging, age-related pathologies, and tumorigenesis.

Original languageEnglish (US)
Pages (from-to)21061-21066
Number of pages6
JournalJournal of Biological Chemistry
Volume280
Issue number22
DOIs
StatePublished - Jun 3 2005

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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    Godley, B. F., Shamsi, F. A., Liang, F. Q., Jarrett, S. G., Davies, S., & Boulton, M. (2005). Blue light induces mitochondrial DNA damage and free radical production in epithelial cells. Journal of Biological Chemistry, 280(22), 21061-21066. https://doi.org/10.1074/jbc.M502194200