title: Orphan nuclear receptor Nur77 regulates androgen receptor gene expression in mouse ovary.
abstract: The androgen receptor (AR) is a nuclear receptor that is expressed in growing follicles and involved in folliculogenesis and follicle growth. The orphan nuclear receptor, Nur77, also has an important role in steroid signaling and follicle maturation. We hypothesized that AR levels and androgen signaling through AR are regulated by Nur77 in the ovary. In the ovaries of Nur77 knockout mice (n = 5), real-time PCR results showed that the mRNA levels of AR and an androgen signaling target gene, Kitl, were decreased by 35% and 24%, respectively, relative to wild-type mice (n = 5), which suggested transcriptional regulation of AR by Nur77 in vivo. In cultured mouse granulosa cells and a steroidogenic human ovarian granulosa-like tumor cell line, KGN, mRNA and protein expression levels of AR were increased by overexpressing Nur77 but decreased by knocking down endogenous Nur77. Consistent with increased AR expression, chromatin immunoprecipitation showed that Nur77 bound to the NGFI-B response element (NBRE) in the AR promoter sequence. AR promoter activity was stimulated by Nur77 in HEK293T cells and attenuated in Nur77 knockout mouse granulosa cells (luciferase assay). Overexpression of Nur77 enhanced the androgenic induction of Kitl (200 nM; 48h), while knockout of Nur77 attenuated this induction. These results demonstrate that AR is regulated by Nur77 in the ovaries, and they suggest that the participation of Nur77 in androgen signaling may be essential for normal follicular development.
authors: Reproductive Medicine Center, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, People's Republic of China.
authors: Anyi
authors: A
authors: Dai
authors: Guijun
authors: G
authors: Yan
authors: Qinyuan
authors: Q
authors: He
authors: Yue
authors: Y
authors: Jiang
authors: Qun
authors: Q
authors: Zhang
authors: Ting
authors: T
authors: Fang
authors: Lijun
authors: L
authors: Ding
authors: Jianxin
authors: J
authors: Sun
authors: Haixiang
authors: H
authors: Sun
authors: Yali
authors: Y
authors: Hu
mesh_terms: D000818:Animals; D015153:Blotting, Western; D047369:Chromatin Immunoprecipitation; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology*; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1 / Q000502:physiology*; D010053:Ovary / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D011944:Receptors, Androgen / Q000235:genetics*
chemical_list: D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D012333:RNA, Messenger; D011944:Receptors, Androgen