Forkhead box L2 (FOXL2) is an indispensable key regulator of female follicular development, and it plays important roles in the morphogenesis, proliferation, and differentiation of follicle granulosa cells, such as establishing normal estradiol signaling and regulating steroid hormone synthesis. Nevertheless, the effects of FOXL2 on granulosa cell morphology and the underlying mechanism remain unknown. Using FOXL2 ChIP-seq analysis, we found that FOXL2 target genes were significantly enriched in the actin cytoskeleton-related pathways. We confirmed that FOXL2 inhibited the expression of RhoA, a key gene for actin cytoskeleton rearrangement, by binding to TCATCCATCTCT in RhoA promoter region. In addition, FOXL2 overexpression in granulosa cells induced the depolymerization of F-actin and disordered the actin filaments, resulting in a slowdown in the expansion of granulosa cells, while FOXL2 silencing inhibited F-actin depolymerization and stabilized the actin filaments, thereby accelerating granulosa cell expansion. RhoA/ROCK pathway inhibitor Y-27632 exhibited similar effects to FOXL2 overexpression, even reversed the actin polymerization in FOXL2 silencing granulosa cells. This study revealed for the first time that FOXL2 regulated granulosa cell actin cytoskeleton by RhoA/ROCK pathway, thus affecting granulosa cell expansion. Our findings provide new insights for constructing the regulatory network of FOXL2 and propose a potential mechanism for facilitating rapid follicle expansion, thereby laying a foundation for further understanding follicular development.

Premature ovarian insufficiency (POI) is a major cause of female infertility due to early loss of ovarian function. POI is a heterogeneous condition, and its molecular etiology is unclear. To identify genetic variants associated with POI, here we performed whole-exome sequencing in a cohort of 1,030 patients with POI. We detected 195 pathogenic/likely pathogenic variants in 59 known POI-causative genes, accounting for 193 (18.7%) cases. Association analyses comparing the POI cohort with a control cohort of 5,000 individuals without POI identified 20 further POI-associated genes with a significantly higher burden of loss-of-function variants. Functional annotations of these novel 20 genes indicated their involvement in ovarian development and function, including gonadogenesis (LGR4 and PRDM1), meiosis (CPEB1, KASH5, MCMDC2, MEIOSIN, NUP43, RFWD3, SHOC1, SLX4 and STRA8) and folliculogenesis and ovulation (ALOX12, BMP6, H1-8, HMMR, HSD17B1, MST1R, PPM1B, ZAR1 and ZP3). Cumulatively, pathogenic and likely pathogenic variants in known POI-causative and novel POI-associated genes contributed to 242 (23.5%) cases. Further genotype-phenotype correlation analyses indicated that genetic contribution was higher in cases with primary amenorrhea compared to that in cases with secondary amenorrhea. This study expands understanding of the genetic landscape underlying POI and presents insights that have the potential to improve the utility of diagnostic genetic screenings.

Background Premature ovarian insufficiency refers to the loss of ovarian function before 40 years of age. The etiology is heterogeneous, and genetic factors account for 20–25% of cases. However, how to transform genetic findings to clinical molecular diagnose remains a challenge. To identify potential causative variations for POI, a next generation sequencing panel with 28 known causative genes of POI was designed, and a large cohort of 500 Chinese Han patients was screened directly. Pathogenic evaluation of the identified variants and the phenotype analysis were performed according to monogenic or oligogenic variants. Results A total of 14.4% (72/500) of the patients carried 61 pathogenic or likely pathogenic variants in 19 of the genes in the panel. Interestingly, 58 variants (95.1%, 58/61) were firstly identified in patients with POI. FOXL2 harbored the highest occurrence frequency (3.2%, 16/500), among whom presented with isolated ovarian insufficiency instead of blepharophimosis-ptosis-epicanthus inversus syndrome. Moreover, luciferase reporter assay confirmed variant p.R349G, which account for 2.6% of POI cases, impaired the transcriptional repressive effect of FOXL2 on CYP17A1 . The novel compound heterozygous variants in NOBOX and MSH4 were confirmed by pedigree haplotype analysis, and digenic heterozygous variants in MSH4 and MSH5 were firstly identified. Furthermore, nine patients (1.8%, 9/500) with digenic or multigenic pathogenic variants presented with delayed menarche, early onset of POI and high prevalence of primary amenorrhea compared with those with monogenic variation(s). Conclusions The genetic architecture of POI has been enriched through the targeted gene panel in a large cohort of patients with POI. Specific variants in pleiotropic genes may result in isolated POI rather than syndromic POI, whereas oligogenic defects might have cumulative deleterious effects on the severity of POI phenotype.

Context Premature ovarian insufficiency (POI) and nonobstructive azoospermia (NOA) are the most severe diseases causing irreversible infertility in females and males, respectively. The contribution of synaptonemal complex (SC) gene variations in the pathogenesis of sporadic patients with POI and NOA has not been systematically illustrated. Objective To investigate the role of SC genes in the pathogenesis of sporadic POI and NOA. Design Genetic and functional study. Setting University-based reproductive medicine center. Patient(s) A total of 1030 patients with sporadic POI and 400 patients with sporadic NOA. Intervention(s) The variations of SC genes were filtered in the in-house database of whole exome sequencing performed in 1030 patients with sporadic POI and 400 patients with sporadic NOA. The pathogenic or likely pathogenic variations following recessive inheritance mode were selected according to American College of Medical Genetics and Genomics (ACMG) guidelines and confirmed by Sanger sequencing. The pathogenic effects of the variations were verified by functional studies. Main Outcome Measure(s) ACMG classification and functional characteristics. Result(s) Two homozygous variations of C14ORF39 and 2 recessive variations of SYCE1 were first identified in sporadic patients with POI and NOA, respectively. Functional studies showed the C14ORF39 variations significantly accelerated the protein degradation and the variations in SYCE1 disrupted its interaction with SYCP1 or C14ORF39, both of which affected SC assembly and meiosis. Conclusion(s) Our study identified novel pathogenic variations of C14ORF39 and SYCE1 in sporadic patients with POI or NOA, highlighting the essential role of SC genes in the maintenance of ovarian and testicular function.

The differences in reproductive processes at the molecular level between viviparous and oviparous animals are evident, and the site in the ovary that synthesizes sex hormones (androgens and oestrogens) and the trends for enriching sex hormones during follicle development in chickens are different from those in mammals, suggesting that the effect of sex hormones on follicle development in chickens is probably different from that in viviparous animals. To explore the specific role of androgen receptors (ARs) on chicken follicular development, we matched the correspondence of follicular development stages among chickens, humans, cows and identified chicken-specific genes related to follicle development (GAL-SPGs) by comparing follicle development-related genes and their biological functions among species (chickens, humans, and cows). A comparison of the core transcription factor regulatory network of granulosa cells (or ovaries) based on super-enhancers among species (chicken, human, and mouse) revealed that AR is a core transcriptional regulator specific to chickens. In vivo experiments showed that inhibition of AR significantly reduced the number of syf (selected stage follicles) in chickens and decreased the expression of GAL-SPGs in F5 follicles, while in vitro experiments showed that inhibition of AR expression in chicken granulosa cells (GCs) significantly down-regulated the expression levels of GAL-SPGs, indicating that AR could regulate follicle selection through chicken-specific genes related to follicle development. A comparison among species (77 vertebrates) of the conserved genomic regions, where chicken super-enhancers are located, revealed that the chicken AR super-enhancer region is conserved in birds, suggesting that the role of AR in follicle selection maybe widespread in birds. In summary, we found that AR can regulate follicle selection through chicken-specific genes related to follicle development, which also emphasizes the important role of AR in follicle selection in chickens and provides a new perspective for understanding the unique process of follicle development in chickens. Our study will contribute to the application of androgens to the control of egg production in chickens and suggests that researchers can delve into the mechanisms of follicle development in birds based on androgen/androgen receptors.

RESEARCH QUESTION:Is thyroid autoimmunity (TAI) associated with the decline of ovarian reserve in euthyroid women? DESIGN:Case-control study. Data from 4302 euthyroid women with normal ovarian reserve (NOR) and low ovarian reserve (LOR), including biochemical premature ovarian insufficiency (POI) and overt POI, were retrospectively analysed. The prevalence and effect of TAI on ovarian reserve was evaluated between women with NOR and LOR. Status of ovarian insufficiency and TSH levels was further stratified for analysis. The correlation between anti-thyroid peroxidase antibody (TPOAb), anti-thyroglobulin antibody (TgAb) titres and ovarian reserve markers was also determined. RESULTS:The prevalence of positive TAI and TgAb was equally distributed between women with NOR and LOR (P = 0.080, P = 0.172); the prevalence of TPOAb positivity was higher in the LOR group (P = 0.005). After stratifying ovarian reserve and TSH, positive TAI, TPOAb and TGAb were significantly associated with overt POI when TSH was >2.5 µIU/ml (all P < 0.001); no association was observed with biochemical POI or overt POI when TSH was ≤2.5 µIU/ml. No correlation was found between TPOAb, TGAb titres and AMH (P = 0.218, P = 0.368, respectively), and bilateral AFC (P = 0.184, P = 0.315, respectively) in patients with LOR; only TPOAb titre was positively correlated with FSH (P = 0.039). CONCLUSIONS:Among the whole population of euthyroid women, TAI was not associated with low ovarian reserve but was significantly associated with overt POI in women with TSH>2.5 µIU/ml. Further basic studies on underlying mechanisms are needed.

PURPOSE:The etiology of premature ovarian insufficiency (POI) is heterogeneous, and genetic factors account for 20-25% of the patients. The primordial follicle pool is determined by the meiosis process, which is initiated by programmed DNA double strand breaks (DSB) and homologous recombination. The objective of the study is to explore the role of DSB formation genes in POI pathogenesis.METHODS:Variants in DSB formation genes were analyzed from a database of exome sequencing in 1,030 patients with POI. The pathogenic effects of the potentially causative variants were verified by further functional studies.RESULTS:Three pathogenic heterozygous variants in PRDM9 and two in ANKRD31 were identified in seven patients. Functional studies showed the variants in PRDM9 impaired its methyltransferase activity, and the ANKRD31 variations disturbed its interaction with another DSB formation factor REC114 by haploinsufficiency effect, indicating the pathogenic effects of the two genes on ovarian function were dosage dependent.CONCLUSION:Our study identified pathogenic variants of PRDM9 and ANKRD31 in POI patients, shedding new light on the contribution of meiotic DSB formation genes in ovarian development, further expanding the genetic architecture of POI.

Objective: To characterize circulating insulin-like factor 3 (INSL3) in different stages of ovarian insufficiency and its role in the evaluation of premature ovarian insufficiency (POI). Design: Retrospective cohort study. Setting: University-based center for reproductive medicine. Patient(s): A total of 145 women, including 48 patients with POI (25 IU/L < follicle-stimulating hormone [FSH] <= 40 IU/L), 49 with biochemical POI (bPOI) (10 IU/L < FSH <= 25 IU/L) and 48 age-matched control women with normal ovarian reserve (FSH <10 IU/L), retrospectively included from the reproductive hospital affiliated with Shandong University between 2017 and 2019. Intervention(s): Levels of INSL3 in the serum and follicular fluid assayed with a commercial radioimmunoassay. Main Outcome Measure(s): Level of INSL3 in serum and follicular fluid among control women and patients with bPOI and POI, its association with different ovarian reserve markers, and its predictive value for bPOI and POI. Result(s): The serum INSL3 level continuously declined with the progress of ovarian insufficiency. It showed strong negative association with FSH (-0.655) and luteinizing hormone (-0.433), but positively correlated with antimullerian hormone (0.617), inhibin B (0.400), antral follicle count (0.630), and testosterone (0.180). Additionally, the circulating INSL3 served as a good predictor for bPOI and POI. No statistically significant difference of INSL3 levels in follicular fluid was observed between bPOI patients and control women. Conclusion(s): For the first time our study has revealed an INSL3 deficiency in women with POI, indicating that circulating INSL3 could serve as a promising theca-cell specific marker for POI. Future research on the role of INSL3 in modulating follicular development, steroidogenesis, and POI pathogenesis is warranted. ((C) 2020 by American Society for Reproductive Medicine.)

Objective To characterize the ovarian reserve indicators for premature ovarian insufficiency (POI) at different disease stages and with various etiologies. Methods According to different FSH levels and menstrual conditions, patients with normal ovarian reserve (NOR with 5 IU/L40 IU/L, n=454) were retrospectively screened and their records were abstracted from Reproductive Hospital Affiliated to Shandong University between 2014 and 2019. Based on the known etiologies, POI patients were subdivided into genetic, iatrogenic, autoimmune and idiopathic subsets according to the known etiologies. The phenotypic features were compared within different subgroups, and the predictive value of ovarian reserve markers was analyzed. Results The ovarian reserve indicators consecutively deteriorated with the progress of ovarian insufficiency, indicated as an increase of FSH and LH but decrease of AMH, inhibin B, AFC, E 2 and T (P<0.01). Most of them changed significantly from NOR to pre-POI while remained relatively stable at a low level or even undetectable at early POI and POF stage. AMH showed the highest predictive value for pre-POI (AUC 0.932, 95% CI 0.918-0.945) and POI (AUC 0.944, 95% CI 0.933-0.954), and the combination of AMH and AFC was highly promising for early prediction. Additionally, significant differences existed in AMH, inhibin B and AFC among women with different etiologies of POI (P<0.05), and the genetic POI presented the worst hormone status. Conclusions Our study indicated a high heterogeneity of POI in both endocrine hormones and etiological phenotypes. The quantitative changes and cutoff values of AMH and AFC could provide new insights in the prediction and early diagnosis of POI.

Forkhead box L2 (FOXL2) is a single-exon gene encoding a forkhead transcription factor, which is mainly expressed in the ovary, eyelids and the pituitary gland. FOXL2 plays an essential role in ovarian development. To reveal the effects of FOXL2 on the biological process and gene expression of ovarian granulosa cells (GCs), we established stable FOXL2-knockdown GCs and then analysed them using transcriptome sequencing. It was observed that knocking down FOXL2 affected the biological processes of cell proliferation, DNA replication, and apoptosis and affected cell cycle progression. FOXL2 knockdown promoted cell proliferation and DNA replication, decreased cell apoptosis, and promoted mitosis. In addition, by comparing the transcriptome after FOXL2 knockdown, we found a series of DEGs (differentially expressed genes) and related pathways. These results indicated that, through mediating these genes and pathways, the FOXL2 might induce the cell proliferation, cycle, and DNA replication, and play a key role during ovarian development and maintenance.

CONTEXT:Premature ovarian insufficiency (POI) is characterized by cessation of menstruation before 40 years of age and elevated serum level of FSH (>25 IU/L). Recent studies have found a few causative genes responsible for POI enriched in meiotic recombination and DNA damage repair pathways.OBJECTIVE:To investigate the role of variations in homologous recombination genes played in POI pathogenesis.METHODS:The whole exome sequencing was performed in 50 POI patients with primary amenorrhea. Functional characterizations of the novel variants were carried out in budding yeast and human cell line.RESULTS:We identified 8 missense variants in 7 homologous recombination genes, including EXO1, RAD51, RMI1, MSH5, MSH2, MSH6, and MLH1. The mutation p.Thr52Ser in EXO1 impaired the meiotic process of budding yeast and p.Glu68Gly in RAD51-altered protein localization in human cells, both of them impaired the efficiency of homologous recombination repair for DNA double-stranded breaks in human cells.CONCLUSIONS:Our study first linked the variants of EXO1 and RAD51 with POI and further highlighted the role of DNA repair genes in ovarian dysgenesis.

The function of oocyte-derived growth differentiation factor 9 (GDF9) in ovarian follicles has thus far been poorly defined in avian species compared with the defined function in mammals. Our aim here is to investigate the effects of GDF9 on steroidogenesis and on chicken ovarian granulosa cell (GC) mitosis. Primary GCs from both prehierarchical (6-8 mm in diameter, phGCs) and preovulatory follicles (F1-F5, poGCs) were cultured in the presence or absence of the GDF9 protein. The progesterone (P4) levels in the culture medium were then measured by radioimmunoassay (RIA), and the expression levels of steroidogenesis genes were detected by quantitative PCR. We found that GDF9 alone showed no significant effect on the P4 levels by regulating the expression of steroidogenesis genes, such as STAR, CYP11A1 and HSD3B. Further experiments indicated that GDF9 promoted follicle-stimulating hormone (FSH)-induced P4 production and STAR expression. GDF9 also rescued the FSH-induced decrease of FSH receptor (FSHR) expression but had no effect on the forskolin-induced P4, STAR and forskolin-inhibited FSHR expression levels, suggesting that GDF9 might achieve its regulatory role of P4 by enhancing FSHR and STAR expression. In addition, GDF9 also promoted GC cell cycle progression, regulated the gene transcription of related genes, potentiated DNA replication and inhibited apoptosis. Interestingly, these effects differed between the phGCs and the poGCs. To our knowledge, this is the first report that illustrates the function of GDF9 on chicken GCs and the effects on ovarian steroidogenesis. Our findings highlight the regulation of central oocytes on the surrounding granulosa cells and emphasize the interaction between paracrine signals and endocrine hormones on ovarian progesterone production; these findings contribute to the understanding of the development of avian ovarian follicles.

Blepharophimosis–ptosis–epicanthus inversus syndrome (BPES) is a rare, autosomal dominant disease. There are two clinical types of BPES: type I patients have eyelid abnormalities accompanied by infertility in affected females, while type II patients only display eyelid malformations. Previous studies have reported that the forkhead box L2 (FOXL2) gene mutations cause BPES. To identify plausible FOXL2 mutation in a Chinese family with BPES and infertility Mutational screening of FOXL2 was performed in the affected members and 223 controls. Functional characterization of the novel mutation identified was carried out in vitro by luciferase reporter assay and subcellular localization experiment. A novel heterozygous mutation c.188 T > A (p.I63N) in FOXL2 was identified in two BPES patients in this family. The mutation abolished the transcriptional repression of FOXL2 on the promoters of CYP19A1 and CCND2 genes, as shown by luciferase reporter assays. However, no dominant-negative effect was observed for the mutation, and it did not impact FOXL2 protein nuclear localization and distribution. The mutation c.188 T > A (p.I63N) in FOXL2 might be causative for BPES and infertility in this family and further amplified the spectrum of FOXL2 mutations.

Accumulating evidence has indicated that the genes involved in meiosis are highly correlated with ovarian function. Pumilio 1 (PUM1) is a RNA-binding protein which is involved in the meiotic process. It has been reported that the Pum1 knockout female mice displayed subfertility due to the decrease in primordial follicle pool. The aim of our study is to investigate whether variants of the PUM1 gene are responsible for primary ovarian insufficiency (POI) in Chinese women. We analyzed coding sequence and untranslated regions of the PUM1 gene in 196 Han Chinese women with non-syndromic POI and 192 controls. Seven novel variants were identified, but one of them was synonymous and six were intronic. Besides, seven known single-nucleotide polymorphisms (SNPs) were found, and there were no significant differences in genotype and allele frequencies of the SNPs between patients and controls. The results suggest that the variants in PUM1 may not contribute to POI in Han Chinese women.