Silica nanoparticles inducing the apoptosis of spermatocyte cell through microRNA-450b-3p targeting MTCH2-mediating mitochondrial signaling pathway

Background: Silica nanoparticles (SiNPs) are found in environmental particulate matter and are proven to have adverse effects on fertility. The relationship and underlying mechanisms between miRNAs and apoptosis induced by SiNPs during spermatogenesis is currently ambiguous. Experimental design: The present study was designed to investigate the role of miRNA-450b-3p in the reproductive toxicity caused by SiNPs. In vivo, 40 male mice were randomly divided into control and SiNPs groups, 20 per group. The mice in the SiNPs group were administrated 20 mg/kg SiNPs by tracheal perfusion once every 5 days, for 35 days, and the control group were given the equivalent of a normal luminal saline. In vitro, spermatocyte cells were divided into 0 and 5 μg/mL SiNPs groups, after passaged for 30 generations, the GC-2spd cells in 5 μg/mL SiNPs groups were transfected with miRNA-450b-3p and its mimic and inhibitor. Results: In vivo, the results showed that SiNPs damaged tissue structures of testis, decreased the quantity and quality of the sperm, reduced the expression of miR-450b-3p, and increased the protein expressions of the MTCH2, BID, BAX, Cytochrome C, Caspase-9, and Caspase-3 in the testis. In vitro, SiNPs obviously repressed the viability and increased the LDH level and apoptosis rate, decreased the levels of the miR-450b-3p, significantly enhanced the protein expressions of the MTCH2, BID, BAX, Cytochrome C, Caspase-9, Caspase-3; while the mimic of miR-450b-3p reversed the changes induced by SiNPs, but inhibitor further promoted the effects induced by SiNPs.Conclusion: The result suggested that SiNPs could induce the spermatocyte apoptosis by inhibiting the miR-450b-3p expression to target promoting the MTCH2 resulting in activating mitochondrial apoptotic signaling pathways in the spermatocyte cells.