Mitochondrial DNA as a biosensor of UV exposure in human skin.

Mitochondrial DNA (mtDNA) has been demonstrated to be a reliable biomarker of UV-induced genetic damage in both animal and human skin. Properties of the mitochondrial genome which allow for its use as a biomarker of damage include its presence in multiple copies within a cell, its limited repair mechanisms, and its lack of protective histones. To measure UV-induced mtDNA damage (particularly in the form of strand breaks), real-time quantitative PCR (qPCR) is used, based on the observation that PCR amplification efficiency is decreased in the presence of high levels of damage. Here, we describe the measurement of UV-induced mtDNA damage, including the extraction of cellular DNA, qPCR to determine the relative amount of mtDNA, qPCR to determine UV-induced damage within a long strand of mtDNA, and the verification of the amplification process using gel electrophoresis.