Purpose: Peroxiredoxin III (PRDX3) is a mitochondrial peroxidase that defends cells against oxidative damage and therefore could play a role in cataract formation. To establish a possible role for PRDX3 in lens function, PRDX3 was localized to specific human lens sub-regions and the levels of PRDX3 in human lens cells and rat lenses exposed to exogenously-added oxidative stress determined.
Methods: PRDX3 levels were monitored by RT-PCR, western analysis, and immunofluorescence. PRDX3 levels in human lens epithelial cells and whole rat lenses exposed to H2O2, TBHP, and heat-treatment were also examined relative to untreated controls by RT-PCR and western analysis.
Results: Significant levels of PRDX3 mRNA and protein were detected in human lens epithelia and fiber cells. PRDX3 was localized to the mitochondria in human lens epithelial cells. PRDX3 was highly induced in human lens epithelial cells by as little as 2 microM H2O2 and by 50 microM H2O2 in cultured rat lenses. Induction of PRDX3 was specific for H2O2 in cultured lens cells since sub-lethal levels of TBHP or heat-shock did not result in detectable increases in the level of PRDX3.
Conclusions: These data demonstrate that PRDX3 is present throughout the lens and localized to the mitochondria in lens epithelial cells. PRDX3 was specifically induced by low levels of H2O2 in human lens epithelial cells and rat lenses suggesting that induction of PRDX3 is an acute response of the lens to increased H2O2 levels. These data provide evidence for an important role for PRDX3 in lens H2O2-detoxification, mitochondrial maintenance, and possibly cataract formation.