Analysis of the Protective Mechanism of PGC-1α/NRF1/2/TFAM Pathway in Cortical Neuron Injury Induced by Oxidative Stress.

To develop the theoretical basis for neuronal antioxidant therapy, the study employed in vitro model of oxidative stress of cortical neurons in order to examine the repair mechanisms triggered in the damaged neurons by PGC-1α/NRF1/NRF2/TFAM signal pathway. The functions of proteins in this signal pathway were examined using online STRING software, which analyzed the network of protein-protein interactions (PPI). The hub genes in PGC-1α/NRF1/NRF2/TFAM signal pathway were analyzed with Cytoscape software. In vitro, the cortical neurons were treated with 25, 50, 75, or 100 μM H2O2. The inhibition rate of neurons with various concentrations of H2O2 was assessed by CCK8, thereupon the neuronal cells were exposed to H2O2 in optimal concentration of 75 μM for 24, 48, or 72 h. The time-dependent changes in the expression of PGC-1α, NRF1, NRF2, ATP-5α, and TFAM in neurons damaged by H2O2-induced oxidative stress were analyzed by Western blotting. The ROS level in damaged neurons, the value of mitochondrial membrane potential (MMP), permeability of mitochondrial permeability transition pores (MPTP), and apoptosis of neurons were analyzed by flow cytometry. Analysis of PPI network showed that transcriptional coactivator PGC-1α is the key regulator of energy metabolism in the cortical neurons, while NRF1 and NRF2 play important roles in mitochondrial biogenesis and in the response to oxidative stress. TFAM is required for basal transcription of mitochondrial DNA, and it is a hub gene in PGC-1α/NRF1/NRF2 pathway. Western blotting and flow cytometry showed that during the development of oxidative stress, PGC-1α activated the expression of NRF1, NRF2, and TFAM and simultaneously prevents MPP loss and MPTP opening. At this, NRF1/NRF2 diminished ROS level and reduced apoptosis, while TFAM enhanced expression of ATP-5α. Therefore, PGC-1α exerts the antioxidant and antiapoptotic effects in cortical neurons exposed to oxidative stress via activation of NRF1/NRF2/TFAM signal pathway.