p53-Dependent pathway and the opening of mPTP mediate the apoptosis of co-cultured Sertoli-germ cells induced by microcystin-LR.

Microcystin-LR (MC-LR), a potent endotoxin, can induce reproductive toxicity. In order to investigate the role and mechanisms of apoptosis (p53-dependent and mitochondrial pathways) of germ cells induced by MC-LR, the co-cultured primary Sertoli-germ cells from Sprague-Dawley rats were used for the experiments. Expression levels of proteins, genes, and mitochondrial membrane potential (MMP) were obtained after exposing co-cultured Sertoli-germ cells to MC-LR with or without the addition of the p53 inhibitor, pifithrin-α (PFT-α), and MMP inhibitor, cyclosporin A (CsA). Results indicated that MC-LR could activate p53-dependent pathway-associated proteins in Sertoli-germ cells, leading to a decrease in MMP (indicating the opening of mitochondrial permeability transition pore [mPTP] and the release of Cytochrome-c [Cyt-c]) from the mitochondria into the cytoplasm and eventually the induction of apoptosis. PFT-α inhibited the expression ofp53, ameliorated the MMP of the co-cultured Sertoli-germ cells, and prevented the release of Cyt-c from the mitochondria into the cytoplasm, which reduces the occurrence of apoptosis. Similarly, the decreased release of Cyt-c from the mitochondria into the cytoplasm and the declined level of apoptosis in Sertoli-germ cells induced by MC-LR were observed after the addition of CsA. These results indicated that the apoptosis of the co-cultured Sertoli-germ cells induced by MC-LR was mediated by the p53-dependent pathway, with the involvement of the opening of mPTP.