Curcumin protects retinal neuronal cells against oxidative stress-induced damage by regulating mitochondrial dynamics.

Oxidative stress plays a crucial role in the damage of retinal neuronal cells. Curcumin, the phytocompound, has anti-inflammatory and antioxidative properties. It was shown that curcumin exerted a beneficial effect on retinal neuronal cell survival. However, the role of mitochondrial dynamics in curcumin-mediated protective effect on retinal neuronal cells remains to be elucidated. Here, H ₂ O ₂ was used to mimic the oxidative stress in retinal neuronal R28 cells. Drp1 and Mfn2 are key regulators of mitochondrial fission and fusion. 100 μM of H ₂ O ₂ significantly increased the cleavage of caspase-3 and Drp1 expression, but downregulated the expression of Mfn2. Pretreatment with 5 μM curcumin effectively alleviated H ₂ O ₂ -induced alterations in the expression of Drp1 and Mfn2 and mitochondrial fission in R28 cells. In addition, curcumin and Drp1 knockdown prevented H ₂ O ₂ -induced intracellular ROS increment and mitochondrial membrane potential disruption. On the contrary, knockdown of Mfn2 diminished curcumin-mediated protection against ROS increment and mitochondrial membrane potential disruption after H ₂ O ₂ . Moreover, curcumin protected R28 cells against H ₂ O ₂ -induced PINK1 expression, mitophagy, caspase-3 cleavage and apoptosis. Knockdown of Mfn2 significantly alleviated the protective effect of curcumin on R28 cells after H ₂ O ₂ . Taken together, our data indicate that curcumin protects against oxidative stress-induced injury in retinal neuronal cells by promoting mitochondrial fusion.
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