Fig. 2.

Levels of mitochondrial COX1 and VDAC, and DNA (mtDNA) are significantly reduced in the cerebral cortex of Sirt3^−/− mice but not WT mice during aging. A, C Immunoblots of COX1 and VDAC proteins in cortical tissue of WT (A) and Sirt3^−/− (C) mice at different ages (8, 12, 16 and 20 months). Actin was used as a loading control. B, D COX1 and VDAC levels (densitometric analysis) were normalized to actin protein levels and expressed as a percentage of the value for 8-month-old WT mice (B) or Sirt3^−/− mice (D). Values are mean ± SEM (n = 6 mice). **p < 0.01 (One-way ANOVA with Tukey post hoc test). E, F A representative gel showing mtDNA (left) and results of measurement of the amount of mtDNA normalized to total protein concentration in cortical tissue from 20-month-old WT and Sirt3^−/− mice. Values are mean ± SEM (n = 3–5 mice). *p < 0.05 (Student’s t test)