Solar radiation and pollution: a mitochondrial perspective.

Although the mitochondrion is central to the genotoxic stress response, it has not received the attention commensurate with its importance. Thanks to the development of novel methods for isolating and internalizing functional mitochondria as well as techniques to analyze their condition, we can now better advance our knowledge on the subject. With increasing evidence of the toxic synergy between UV and pollutant for skin, we have investigated the phototoxicity of benzo[a]pyrene (BaP), a ubiquitous lipophilic atmospheric pollutant, in mitochondria. We have demonstrated the specific affinity of BaP to mitochondrial membrane. When combined with UVA, BaP-exposed mitochondria, have an increased lipid peroxidation, which is accompanied with markers of mitochondrial stress. After showing that UV exposure is accompanied with an increase in mitochondrial transfer between cells, we decided to investigate the implication of mitochondria in UV-induced cell death. Using internalization of exogenous mitochondria techniques, we show that incorporation of undamaged mitochondria following a lethal UV stress prevent apoptosis in fibroblasts. This prevention occurs even if the cells are well engaged in the apoptosis, which strongly suggest that mitochondria are implicated in anastasis.