Perxiredoxin4, a protein which shows protective effect on ovarian function

Abstract

Peroxiredoxin4 (Prdx4) is a member of Prdx family. As revealed by our previous research work, the expression of Prdx4 was in close contact with ovary-aging. Furthermore, we also discovered that it was located in endoplasmic resticulum (ER) of granular cell and involved in regulating the endoplasmic reticulum stress (ER stress) in granulosa cell. This research work aimed at exploring the protective effect and the molecular mechanism of Prdx4 on ovarian function. Mice were divided into two groups: Prdx4-KO and wild type group. The indicators of ovarian function, oxidative stress and ER stress pathways-associated markers were compared between the two groups. We established mice model with gene prdx4 knock out by the CRISPR/Cas9 technology. All mice aged 8 months were sacrificed and then blood was collected by removing eyeball. The left ovary was immediately excised and stored at -80°C for biochemical analysis and the right ovary was fixed in 4% paraformaldehyde for histological studies. For the purpose of evaluating the protective effect of Prdx4 on ovarian function, we calculated ovary-to-body weight ratio. Secondly, we detected the level of AMH and expression of senescence-associated protein P16 with the help of real-time PCR and immunohistochemistry correspondingly. Thirdly, the number of different types of follicles were counted by hematoxylin and eosin (H&E) staining for the assessment of ovarian reserve. Eventually, the levels of 4-HNE, 8-OHdG, NTY, and three ER stress pathways related markers were examined by immunohistochemistry and real-time PCR. All the statistical analyses were performed using SPSS v.16. software. All the statistical comparisons between the two groups were analysed by t test. In comparison with the control group, the prdx4-KO group presented significantly smaller ovary weight/body weight ratio (p<0.05), lower level of AMH, higher expression of senescence-associated protein P16, and lower proportion of primordial follicles (p<0.05). In addition, the prdx4-KO group expressed higher 8-OHdG, 4-HNE, NTY. By screening three pathways of ER stress, we found that ATF4 changed obviously. The level of ATF4 and CHOP were up-regulated in ER. Prdx4 may contribute to the ovarian function protection. As for the molecular mechanism of Prdx4 on ovarian function, we hypothesized that Prdx4 may inhibit ER stress through PERK-eIF2α-ATF4-GADDl53/CHOP pathway in granulosa cells.