Alternative splicing of the androgen receptor in polycystic ovary syndrome

Abstract

Polycystic ovary syndrome (PCOS) is one of the most common female endocrine disorders and a leading cause of female subfertility. The mechanism underlying the pathophysiology of PCOS remains to be illustrated. Here, we identify two alternative splice variants (ASVs) of the androgen receptor (AR), insertion and deletion isoforms, in granulosa cells (GCs) in ∼62% of patients with PCOS. AR ASVs are strongly associated with remarkable hyperandrogenism and abnormalities in folliculogenesis, and are absent from all control subjects without PCOS. Alternative splicing dramatically alters genome-wide AR recruitment and androgeninduced expression of genes related to androgen metabolism and folliculogenesis in human GCs. These findings establish alternative splicing of AR in GCs as the major pathogenic mechanism for hyperandrogenism and abnormal folliculogenesis in PCOS.n ovarian follicles, oocytes are surrounded by granulosa cells (GCs), which have crucial endocrine functions. Polycystic ovary syndrome (PCOS) is a heterogeneous hormonal disorder affecting one in 15 women, and is one of the most common causes of female infertility (1). Hyperandrogenism and abnormal follicle development, associated with excessively small follicles and ovulatory dysfunction largely due to GCs dysfunction, characterize the pathogenesis of PCOS. Although the underlying etiology remains unclear, androgens and the androgen receptor (AR) are considered important on account of their critical roles in the prevalence of hyperandrogenism and ovarian folliculogenesis in this disorder (1-3).Androgens elicit their effects upon binding to AR, and AR functions primarily via genomic activities as a nuclear receptor. In the ovary, AR is predominantly expressed by GCs throughout most stages of follicular development. Nearly all reproductive phenotypes observed in global AR knockout mice have been attributed to a lack of AR expression in GCs (3). Haploinsufficiency for exon 3-deleted mutant AR is associated with a premature reduction in female fecundity (4), verifying the crucial role of classical genomic AR activity in normal ovarian function. Clinical studies have suggested that PCOS might be associated with AR (CAG)n repeats (5) and rs6152A (6) gene polymorphisms. These studies promoted interest in investigating the effects of AR in GC dysfunction in PCOS women. We therefore hypothesized that abnormally expressed and/or dysfunctional AR plays an important role in the pathogenesis of PCOS. ResultsAlternative Splice Variants of AR in GCs of PCOS Women. Nested RT-PCR (Fig. S1A) was used to amplify AR cDNAs from GCs of Southeastern Han Chinese women undergoing in vitro fertilization and embryo transfer. We identified two alternative splice variants (ASVs) expressed exclusively in PCOS women. One ASV inserted 69 bp into intron 2 (ivs2) between exons 2 and 3 (insertion isoform, ins) whereas the other skipped exon 3 (deletion isoform, del), as demonstrated by agarose gel electrophoresis (Fig. 1A) and PCR product sequencing (Fig. 1B). AR ASVs were not detected in ...

Western-style diet, with and without chronic androgen treatment, alters the number, structure, and function of small antral follicles in ovaries of young adult monkeys

“…More recently, genomic information was reported from women with PCOS by GWAS studies (48, 49). While we did observe changes in AR expression, which displays altered expression in a cohort of women with PCOS (50), there were no changes in mRNA levels of the recently identified PCOS-associated mRNA DENND1A (48). The function of DENND1A is in membrane associated endocytosis and receptor trafficking; there is some evidence that expression of a DENND1A variant increases androgen production in a human theca cell model (51).…”

Endocrine disrupting effects of tebuconazole on different life stages of zebrafish (Danio rerio)

“…Multiple regulatory elements have been observed in Cyp19a promoter in zebrafish (Zhao et al, 2017). Wang et al (2015c) demonstrated that diminished binding of the androgen-androgen receptor complex to the androgen responsive element in Cyp19a1 promoter resulted in suppression of aromatase expression. Similarly, down-regulated estrogen would be expected to decrease the binding to the estrogen responsive elements in Cyp19a promoter.…”

Effects of androgen on immunohistochemical localization of androgen receptor and Connexin 43 in mouse ovary

“…Notably, AR had been suggested to regulate signaling pathways occurring in granulosa cells, and granulosa cells-specific AR appeared to promote preantral follicle growth and prevent follicular atresia, it was essential for normal follicular development and fertility (Sen and Hammes, 2010;Duggavathi and Murphy, 2009). Recent reports have documented that AR was widely believed to be an important regulator of granulosa cells biology, high expression of AR in granulosa cells was primarily considered to associate with PCOS (Yang et al, 2014;Wang et al, 2015). While androgen excess enhanced follicular development and dysfunction formation of antral follicles leading to PCOS, low androgen levels may be associated with abnormalities of follicular growth (Prizant et al, 2014).…”