Small Peptides from Periplaneta americana Inhibits Oxidative Stress-Induced KGN Cell Apoptosis by Regulating Mitochondrial Function Through Bcl2L13

This study examined the protective effects of small peptides from Periplaneta americana against H2O2-induced mitochondrial injury in human ovarian granulosa cells. The ATP level and mitochondrial membrane potential as well as the quantity and ultrastructure of mitochondria in cells were detected. Mitochondrial DNA copy number and expression levels of Bcl2L13, LC3B, and p62 were tested. Targeted silencing of Bcl2L13 expression in KGN cells. The expression levels of Bcl2L13 and LC3B as well as interaction were evaluated. The ATP level, mtDNA-CN, and MMP of the H2O2 group were significantly lower than those of the normal control group (P < 0.05), accompanied by a reduction in mitochondrial mass and mitochondrial fluorescence intensity (P < 0.05). However, the ATP level, mtDNA, and MMP in KGN cells were increased after SPPA treatment (P < 0.05). Scanning electron microscopy shows that SPPA ameliorates H2O2-induced structural damage to mitochondria. Moreover, the expression levels of Bcl2L13 and p62 in the H2O2 group were downregulated significantly compared with those of the normal control group (P < 0.05), while LC3B was upregulated (P < 0.05). After SPPA treatment, the expression levels of Bcl2L13 and p62 were upregulated (P < 0.05), while LC3B was downregulated (P < 0.05). The Co-IP results indicated that Bcl2L13 and LC3B interacted, and this interaction was weakened after cell treatment with H2O2, and dissociation between Bcl2L13 and LC3B declined after SPPA treatment. SPPA inhibits KGN cell apoptosis induced by oxidative stress via inhibition of mitochondrial injury Bcl2L13-mediated mitochondrial autophagy might participate in the regulation process.