Mitochondrial oxidative damage and mtDNA deletions in cardiac aging. (A). Mitochondrial protein carbonyl (nmol/mg) significantly increased in old wild-type (OWT, >24 months) and even more in middle-aged Polg (13.5 months) mouse hearts when compared with young WT mouse hearts. mCAT significantly reduced the age-dependent mitochondrial protein carbonylation. (B) Mitochondrial DNA deletion frequency significantly increased in OWT (>24 months) and young Polg (4 months) when compared with young WT, and this is dramatically increased in middle-aged Polg (13.5 months). mCAT overexpression significantly reduced the deletion frequency for both. *P <0.05 compared with YWT. Modified from Dai et al. [25, 43].