Methionine sulfoxide reductases (Msrs) in lens cells are important for the maintenance of lens cell viability and resistance to oxidative stress damage.
Peroxynitrite (ONOO(-)), as a strong oxidizing and nitrating agent, occurred in
diabetic retinopathy patients and diabetic model animal. In an attempt to shed light on the roles of MsrB1, known as
selenoprotein R, in protecting human lens epithelial (HLE) cells against
peroxynitrite damage, and contribution of loss of its normal activity to
cataract, the influences of MsrB1 gene silencing on
peroxynitrite-induced apoptosis in HLE cells were studied. The results showed that both exogenous
peroxynitrite and MsrB1 gene silencing by
short interfering RNA (
siRNA) independently resulted in oxidative stress, endoplasmic reticulum (ER) stress, activation of
caspase-3 as well as an increase of apoptosis in HLE cells; moreover, when MsrB1-gene-silenced cells were exposed to 300 μM
peroxynitrite, these indexes were further aggravated at the same conditions and
DNA strand breaks occurred. The results demonstrate that in HLE cells MsrB1 may play important roles in regulating redox balance and mitigating ER stress as induced by oxidative stress under physiological conditions; MsrB1 may also protect HLE cells against
peroxynitrite-induced apoptosis by inhibiting the activation of
caspase-3 and oxidative damage of
DNA under pathological conditions. Our results imply that loss of its normal activity is likely to contribute to
cataract.