Polystyrene Nanoparticles Induce Transcriptional Repression in TM4 Sertoli Cells

Polystyrene nanoparticles (PS-NPs) are prevalent environmental contaminants that can accumulate in biological tissues. This study investigates the effects of PS-NPs on TM4 cells, a Sertoli cell line crucial for maintaining the male spermatogenesis microenvironment.TM4 cells were exposed to PS-NPs (0-100 μg/mL) duration of 24 to 72 h. The cytotoxic effects of PS-NPs were assessed by measuring cell viability and membrane integrity. PS-NPs internalization and aggregation were visualized using transmission electron microscopy (TEM). Additionally, transcriptomic sequencing was conducted to identify differentially expressed genes (DEGs) after 48 h of exposure to 100 μg/mL PS-NPs, followed by a qRT-PCR assay to confirm the levels of DEGs. The results showed that PS-NPs were internalized and aggregated within the cytoplasm of TM4 cells. Exposure to PS-NPs did not significantly affect cell viability but compromised membrane integrity and significantly increased the ROS levels. Transcriptomic analysis identified a total of 382 DEGs, with 320 being downregulated and 62 upregulated. GO analysis revealed enrichment in transcriptional regulation processes, while GSEA indicated aberrant DNA methylation patterns. The expression level of the DNA demethylating regulator Tet3 was significantly reduced at both the mRNA and protein levels after exposure to PS-NPs. The levels of four genes (LOX, Zmynd12, Zfp354b, and Ccrl2) were confirmed by qRT-PCR, and their expression levels were consistent with the results after Tet3 knockdown. These findings suggest that PS-NPs induce transcriptional repression in TM4 cells, likely through the downregulation of Tet3, thereby disrupting the balance between DNA methylation and demethylation. This study provides insights into the epigenetic effects of PS-NPs on the male reproductive microenvironment and highlights potential implications for spermatogenesis.