Mitochondrial matrix P53 sensitizes cells to oxidative stress.

A mitochondrial matrix-specific p53 construct (termed p53-290) in HepG2 cells was utilized to determine the impact of p53 in the mitochondrial matrix following oxidative stress. H2O2 exposure reduced cellular proliferation similarly in both p53-290 and vector cells, and p53-290 cells demonstrating decreased cell viability at 1mM H2O2 (~85% viable). Mitochondrial DNA (mtDNA) abundance was decreased in a dose-dependent manner in p53-290 cells while no change was observed in vector cells. Oximetric analysis revealed reduced maximal respiration and reserve capacity in p53-290 cells. Our results demonstrate that mitochondrial matrix p53 sensitizes cells to oxidative stress by reducing mtDNA abundance and mitochondrial function.