title: UV-A irradiation induces a decrease in the mitochondrial respiratory activity of human NCTC 2544 keratinocytes.
abstract: UV-A irradiation caused a dose-dependent decrease in cellular oxygen consumption (56%) and ATP content (65%) in human NCTC 2544 keratinocytes, one hour after treatment. This effect was partially reversed by maintaining the irradiated cells in normal culture conditions for 24 h. Using malate/glutamate or succinate as substrates for mitochondrial electron transport, the oxygen uptake of digitonin-permeabilised cells was greatly inhibited following UV-A exposure. These results strongly suggest that UV-A irradiation affects the state 3 respiration of the mitochondria. However, under identical conditions, UV-A exposure did not reduce the mitochondrial transmembrane potential. The antioxidant, vitamin E inhibited UV-A-induced lipid peroxidation, but did not significantly prevent the UV-A-mediated changes in cellular respiration nor the decrease in ATP content, suggesting that these effects were not the result of UV-A dependent lipid peroxidation. UV-A irradiation also led to an increase in MnSOD gene expression 24 hours after treatment, indicating that the mitochondrial protection system was enhanced in response to UV-A treatment. These findings provide evidence that impairment of mitochondrial respiratory activity is one of the early results of UV-A irradiation for light doses much lower than the minimal erythemal dose.
authors.affiliation: Laboratoire de Dermatologie, INSERM U312, Hôpital Saint-Louis, 1 rue Claude Vellefaux, 75475 Paris, France. mojgan.mergny@curie.fr
authors.forename: M
authors.initials: M
authors.lastname: Djavaheri-Mergny
authors.forename: C
authors.initials: C
authors.lastname: Marsac
authors.forename: C
authors.initials: C
authors.lastname: Mazière
authors.forename: R
authors.initials: R
authors.lastname: Santus
authors.forename: L
authors.initials: L
authors.lastname: Michel
authors.forename: L
authors.initials: L
authors.lastname: Dubertret
authors.forename: J C
authors.initials: JC
authors.lastname: Mazière
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000975:Antioxidants; D002460:Cell Line; D019069:Cell Respiration / Q000502:physiology / Q000528:radiation effects*; D006801:Humans; D007424:Intracellular Fluid / Q000378:metabolism; D007425:Intracellular Membranes / Q000502:physiology / Q000528:radiation effects; D015603:Keratinocytes / Q000166:cytology / Q000528:radiation effects; D008564:Membrane Potentials / Q000528:radiation effects; D008928:Mitochondria / Q000502:physiology / Q000528:radiation effects*; D013482:Superoxide Dismutase / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: D000975:Antioxidants; D000255:Adenosine Triphosphate; D013482:Superoxide Dismutase