Orphan Nuclear Receptor NR4A1 Is a Negative Regulator of DHT-Induced Rat Preantral Follicular Growth

Author:

Xue Kai12,Liu Jia-yin1,Murphy Bruce D.3,Tsang Benjamin K.2

Affiliation:

1. State Key Laboratory in Reproductive Medicine (K.X., J.-Y.L.), Centre for Clinical Reproductive Medicine, Nanjing Medical University, Nanjing 210029, China

2. Departments of Cellular and Molecular Medicine and Obstetrics and Gynecology (K.X., B.K.T.), University of Ottawa, Ottawa, Ontario, Canada K1H 8L6; Chronic Disease Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada K1Y 4E9

3. Centre for Animal Reproduction Research (B.D.M.), University of Montréal, Montréal, Québec, Canada H3T 1C5

Abstract

Abstract Nuclear receptor subfamily 4 group A member1 (NR4A1), an orphan nuclear receptor, is involved in the transcriptional regulation of thecal cell androgen biosynthesis and paracrine factor insulin-like 3 (INSL3) expression. Androgens are known to play an important regulatory role in ovarian follicle growth. Using a chronically androgenized rat model, a preantral follicle culture model and virus-mediated gene delivery, we examined the role and regulation of NR4A1 in the androgenic control of preantral follicular growth. In the present study, Ki67 staining was increased in preantral follicles on ovarian sections from 5α-dihydrotestosterone (DHT)-treated rats. Preantral follicles from DHT-treated rats cultured for 4 d exhibited increased growth and up-regulation of mRNA abundance of G1/S-specific cyclin-D2 (Ccnd2) and FSH receptor (Fshr). Similarly, DHT (1 μm) increased preantral follicular growth and Ccnd2 and Fshr mRNA abundance in vitro. The NR4A1 expression was high in theca cells and was down-regulated by DHT in vivo and in vitro. Forced expression of NR4A1 augmented preantral follicular growth, androstenedione production, and Insl3 expression in vitro. Inhibiting the action of androgen (with androgen receptor antagonist flutamide) or INSL3 (with INSL3 receptor antagonist INSL3 B-chain) reduced NR4A1-induced preantral follicular growth. Furthermore, NR4A1 overexpression enhanced DHT-induced preantral follicular growth, a response attenuated by inhibiting INSL3. In conclusion, DHT promotes preantral follicular growth and attenuates thecal NR4A1 expression in vivo and in vitro. Our findings are consistent with the notion that NR4A1 serves as an important point of negative feedback to minimize the excessive preantral follicle growth in hyperandrogenism.

Publisher

The Endocrine Society

Subject

Endocrinology,Molecular Biology,General Medicine

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