Protective effect of Homer 1a against hydrogen peroxide-induced oxidative stress in PC12 cells.

Oxidative stress-induced cell damage is involved in many neurological diseases. Homer protein, as an important scaffold protein at postsynaptic density, regulates synaptic structure and function. Here, we reported that hydrogen peroxide (H2O2) induced the expression of Homer 1a. Down-regulation of Homer 1a with a specific small interfering RNA (siRNA) exacerbated H2O2-induced cell injury. Up-regulation of Homer 1a by lentivirus transfection did not affect the anti-oxidant activity, but significantly reduced the reactive oxygen species (ROS) production and lipid peroxidation after H2O2-induced oxidative stress. Overexpression of Homer 1a attenuated the loss of mitochondrial membrane potential (MMP) and ATP production induced by H2O2, and subsequently inhibited mitochondrial dysfunction-induced cytochrome c release, increase of Bax/Bcl-2 ratio and caspase-9/caspase-3 activity. Furthermore, in the presence of BAPTA-AM, an intracellular free-calcium (Ca2+) chelator, overexpression of Homer 1a had no significant effects on H2O2-induced oxidative stress. These results suggest that Homer 1a has protective effects against H2O2-induced oxidative stress by reducing ROS accumulation and activation of mitochondrial apoptotic pathway, and these protective effects are dependent on the regulation of intracellular Ca2+ homeostasis.