The Mechanism of Melatonin and Its Receptor MT2 Involved in the Development of Bovine Granulosa Cells

Shujuan Wang,Wenju Liu,Guodong Liu,Xunsheng Pang,Sifa Dai

doi:10.3390/ijms19072028

Abstract

Ovarian granulosa cells (GCs) are a critical approach to investigate the mechanism of gene regulation during folliculogenesis. The objective of this study was to investigate the role of MT2 in bovine GCs, and assess whether MT2 silencing affected GCs response to melatonin. We found that MT2 silencing significantly decreased the secretion of progesterone and estradiol, and increased the concentration of inhibin B and activin B. To further reveal the regulatory mechanism of MT2 silencing on steroids synthesis, it was found that the expression of CYP19A1 and CYP11A1 enzymes (steroid hormone synthesis) were down-regulated, while genes related to hormonal synthesis (StAR, RUNX2, INHA and INHBB) were up-regulated without affecting the expression of INHBA, suggesting that MT2 silencing may regulate hormone abundance. Furthermore, MT2 silencing significantly increased the expression of TGFBR3 and BMP6, and decreased the expression of LHR and DNMT1A without significant difference in the expression of FSHR and EGFR. In addition, MT2 silencing didn’t affect the effect of melatonin on increasing the expression of DNMT1A, EGFR, INHBA and LHR, and progesterone level, or decreasing INHA, TGFBR3 and StAR expression, and production of inhibin B. Moreover, MT2 silencing could disrupt the role of melatonin in decreasing the FSHR, INHBB and BMP6 expression, and activin B secretion. In conclusion, these results reveal that melatonin and MT2 are essential regulator of bovine GCs function by modulating reproduction-related genes expression, hormones secretion and other regulators of folliculogenesis.

Highlights

Ovarian folliculogenesis is a complicated process and it occurs from the primordial follicles before or immediately after birth [1]
The results showed that MT2 silencing significantly downregulated the expression of CYP19A1, which encodes the rate limiting step for oestradiol synthesis, while it significantly upregulated RUNX2 expression, and there were no significant difference in the expression of CYP19A1 and RUNX2 after melatonin treatment compared to the pshRNA-scramble group (Figure 3C,E)
Based on our present data, we demonstrated the biological actions of melatonin and MT2 in modulating reproduction related genes expression, hormone secretion and other regulators of folliculogenesis

Summary

Introduction

Ovarian folliculogenesis is a complicated process and it occurs from the primordial follicles before or immediately after birth [1]. The folliculogenesis mainly include the following process: primordial follicles are activated to grow into primary follicles and subsequently into secondary follicles; antral follicles are formed, and further developed antral follicles are ovulated [2]. GCs are useful models for investigating the molecular mechanisms of gene regulation during folliculogenesis [9].

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