Tris(1,3-dichloro-2-propyl) phosphate induces endoplasmic reticulum stress and mitochondrial-dependent apoptosis in mouse spermatocyte GC-2 cells

Tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) is a frequently detected organophosphorus flame retardants (OPFRs) in various environmental media, and has been evidenced as reproductive toxicity. However, its adverse effects on spermatogenic cells are unknown. In this study, mouse spermatocyte GC-2spd (GC-2) cells were selected as an in vitro model, and the impact of mitochondrial structure and function, endoplasmic reticulum (ER) stress, cell apoptosis and the related molecular mechanisms were investigated. Our study indicated that cell viability was decreased significantly in a dose-dependent manner after TDCIPP treatment with the half lethal concentration (LC50) at 82.8 μM, 50.0 μM and 39.6 μM for 24 h, 48 h and 72 h, respectively. An apoptosis was observed by Annexin V-FITC/PI stain. In addition, fragmentation of mitochondrial structure, an increase of mitochondrial membrane potential (MMP), reduction of cellular adenosine triphosphate (ATP) content, release of cytochrome c and activation of Caspase-3 and Caspase-9 activity implicated that Caspase-3 dependent mitochondrial pathway might play a key role in the process of GC-2 cell apoptosis. Furthermore, ER stress induction was convinced by altered morphology of ER and up-regulation of ER targeting genes, including (Bip, eIF2α, ATF4, XBP1, CHOP, ATF6 and Caspase-12). Taken together, these results demonstrate that both mitochondrial apoptotic pathways and ER stress apoptotic pathways might play important roles in the process of apoptosis in GC-2 cells induced by TDCIPP treatment. Therefore, the potential reproductive toxicity of TDCIPP should not be ignored.