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The zinc oxide nanoparticles (ZnO NPs) is one of the most extensively utilized metal oxide nanoparticles in biomedicine, human food, cosmetics and livestock farming. However, growing evidence suggests that there is a potential risk for humans and animals because of the accumulation of ZnO NPs in cells, which leads to cell death through several different pathways. Nevertheless, the effects of ZnO NPs on porcine granulosa cells (PGCs) and how ZnO NPs regulate the follicular cells are unknown. In this study, we aimed to elucidate the role of ZnO NPs in the porcine ovary by using PGCs. Firstly, we identified the characterization of ZnO NPs used in this study and the results showed that the size of ZnO NPs was 29.0 nm. The results also demonstrated that ZnO NPs impaired cell viability and decreased steroid hormone secretion in PGCs. In addition, ZnO NPs induced reactive oxygen species (ROS) production, leading to oxidative stress of PGCs. Meanwhile, ZnO NPs also triggered autophagy in PGCs by increasing the ratio of LC3-II/LC3-I, along with the expression of SQSTM1 and ATG7. Finally, the results from N-acetylcysteine (NAC) addition suggested that ZnO NPs promoted autophagy through the enhancement of ROS production. In summary, this study demonstrates that ZnO NPs impair the viability and function of PGCs through autophagy, which is regulated by ROS production.

DNA damage and base excision repair (BER) are actively involved in the modulation of DNA methylation and demethylation. However, the underlying molecular mechanisms remain unclear. In this study, we seek to understand the mechanisms by exploring the effects of oxidative DNA damage on the DNA methylation pattern of the tumor suppressor breast cancer 1 (BRCA1) gene in the human embryonic kidney (HEK) HEK293H cells. We found that oxidative DNA damage simultaneously induced DNA demethylation and generation of new methylation sites at the CpGs located at the promoter and transcribed regions of the gene ranging from −189 to +27 in human cells. We demonstrated that DNA damage-induced demethylation was mediated by nucleotide misincorporation by DNA polymerase β (pol β). Surprisingly, we found that the generation of new DNA methylation sites was mediated by coordination between pol β and the de novo DNA methyltransferase, DNA methyltransferase 3b (DNMT3b), through the interaction between the two enzymes in the promoter and encoding regions of the BRCA1 gene. Our study provides the first evidence that oxidative DNA damage can cause dynamic changes in DNA methylation in the BRCA1 gene through the crosstalk between BER and de novo DNA methylation.

Female animals living in the Qinghai-Tibet Plateau have lower ovulation rates because of the hypoxic environment, however, the mechanism of hypoxia on animal follicles is unclear. In this study, the effects of hypoxia on bovine follicles were investigated using an in vitro follicular culture system. The results show that there was a significant decrease in follicular diameter from day 3 to day 6 in both hypoxia and hypoxia with estrogen (E2) and fulvestrant (ICI 182780) (hypoxia + E2 + ICI) groups, when compared with a normoxia group (p < 0.05). We also observed significant downregulation of ERα and FSHR, while upregulation of LHCGR expression in the hypoxia group and hypoxia + E2 + ICI groups compared to the normoxia group (p < 0.05). The expression of IGF1 gene was significantly downregulated in hypoxia + E2 + ICI group when compared to the hypoxia + E2 group (p < 0.05). The expression of HIF1A, ADAMTS1, VEGFA, and EDN2 were upregulated in both hypoxia and hypoxia + E2 + ICI groups in comparison to normoxia group (p < 0.05). Under hypoxic conditions, the addition of E2 resulted in a decrease of HIF1A protein but an increase of ERα protein in cultured bovine follicles (p < 0.05). In summary, hypoxia limits the growth of bovine follicle cultured in vitro through inhibition of ERα.

In the present study, AA was used to challenge bovine ovarian granulosa cells in vitro and the related parameters of cellular and molecular biology were measured. The results indicated that lower doses of AA increased survival of bovine granulosa cells whereas higher doses of AA suppressed survival. While lower doses of AA induced accumulation of lipid droplet in granulosa cells, the higher dose of AA inhibited lipid accumulation, and AA increased abundance of FABP3, CD36 and SLC27A1 mRNA. Higher doses of AA decreased the secretion of E2 and increased the secretion of P4 accompanied by down-regulation of the mRNA abundance of CYP19A1, FSHR, HSD3B1 and STAR in granulosa cells. The signaling pathways employed by AA in the stimulation of genes expression included both ERK1/2 and Akt. Together, AA specifically affects physiological features, gene expression levels and steroid hormone secretion, and thus altering the functionality of granulosa cells of cattle.