Project description:Although it is well established that the ovarian reserve diminishes with increasing age, and that a woman’s age is correlated to lower oocyte quality, the interplay of a diminished reserve and age on oocyte developmental competence is not clear. After maturation, oocytes are mostly transcriptionally quiescent, and developmental competence prior to embryonic genome activation (EGA) relies on maternal RNA and proteins. Age and ovarian reserve both affects oocyte developmental competence, however, their relative importance in this process are difficult to tease out, as ageing is accompanied by a decrease in ovarian reserve. Oocytes store large quantities of RNA, including several noncoding transcripts (ncRNAs) involved in early development transcription and translation modulation. Despite the central role of ncRNAs in maternal to zygote transition, no characterization of the ncRNA transcriptome in human oocytes has been reported. This study aims at identifying how the human oocyte transcriptome changes across reproductive ages and ovarian reserve levels, with the goal of identifying candidate markers of developmental competence, and to assess the independent relevance of age and ovarian reserve in the changes of the transcriptome
Project description:This group consist of human embryologists from the reproductive medical center for of the 1st affiliated hospital of Anhui Medical University. Our research is specifically focused on women ovarian reserve and the relevant female infertility. By deep sequencing, the current experiment determined the small non-coding RNA profile of cumulus cells from patients with or without diminished ovarian reserve undergoing controlled ovarian stimulation and in vitro fertilization treatment. Ovarian follicles, which are a densely-packed shell of granulosa cells that contains an immature or mature oocyte, are above all responsible for the development, maturation, and release of mature egg for fertilization. They are also responsible for synthesizing and secreting hormones that are essential for follicular development, menstrual and estrous cycle, maintenance of the reproductive tracts and their functions, development of female secondary sex characteristics, and metabolism. During folliculogenesis, ovarian granulosa cells surrounding the oocyte differentiate into mural granulosa cells, involved in gonadal steroidogenesis, and into cumulus cells, which are ovulated with the oocyte at ovulation. In the present study, we described the small non-coding RNA expression profile to characterize the ensemble of both known and novel ncRNAs expressed in cumulus cells from patients with or without Diminished ovarian reserve, by using high-throughput Solexa technology.
Project description:To evaluate the mechanisms by which excessive FSH doses during ovarian stimulation are detrimental to ovarian follicle function and assisted reproduction outcomes, small ovarian reserve (SOR) heifers were subjected to ovarian stimulation with either a standard, 70 IU, or excessive, 210 IU, dose of commercial porcine FSH (cpFSH) preparation, per injection. The ovaries were recovered at the end of the ovarian stimulation protocol, consisting of eight cpFSH injections at 12 h intervals. In excessive dose treated heifers, heterogeneity was observed with regards to follicle phenotype including cumulus cell-oocyte complex (COC) morphology and intrafollicular steroid hormone milieu. In contrast, standard-dose treated heifers exhibited one predominant follicle phenotype which was selected as the control follicle type for all comparisons herein. RNA-seq analyses of granulosa, cumulus cells and the oocyte from individual follicles of these defined phenotypes was used to identify changes in the transcriptomes of these cell types in excessive dose treated individuals.
Project description:The ovarian reserve defines the female reproductive lifespan, which in humans spans decades due to robust maintenance of meiotic arrest in oocytes residing in primordial follicles. Epigenetic reprogramming, including DNA demethylation, accompanies meiotic entry, but the chromatin changes that underpin the generation and preservation of ovarian reserves are poorly defined. We report that the Polycomb Repressive Complex 1 (PRC1) establishes repressive chromatin states in perinatal mouse oocytes that directly suppress the gene expression program of meiotic prophase-I and thereby enable the transition to dictyate arrest. PRC1 dysfuction causes depletion of the ovarian reserve and leads to premature ovarian failure. Our study demonstrates a fundamental role for PRC1-mediated gene silencing in female reproductive lifespan, and reveals a critical window of epigenetic programming required to establish ovarian reserve.
Project description:Primary ovarian insufficiency (POI) is a clinical syndrome of ovarian dysfunction characterized by premature exhaustion of primordial follicles. POI causes infertility, serious daily life disturbances and long-term health risks. However, the underlying mechanism remains largely unknown. We have previously identified Basonuclin1 (BNC1) mutation from a large Chinese POI pedigree and find the targeted Bnc1 mutation mouse exhibites POI. In this study, we find that BNC1 plays a key role in the dynamic balance of ovarian reserve, and maintaining lipid metabolism and redox homeostasis in oocytes during follicular development. Deficiency of BNC1 results in premature follicular activation and accelerated follicular atresia, but doesn’t affect the ovarian primordial follicle reserve. Mechanistically, BNC1 targets the NF2-YAP pathway to trigger oocyte ferroptosis. Inhibition of ferroptosis significantly rescues POI. These findings uncover a novel pathologic mechanism of POI based on BNC1 deficiency and is the first report showing ferroptosis involved in oocyte death.
Project description:The mechanisms of oocyte meiotic defects and low competence during ovarian aging remains elusive for decades. Using Hi-C (genome-wide chromatin conformation capture) and Smart RNA-seq of oocytes from 6- weeks or 10- months aged ovaries, the abnormal loose chromatin structures and disturbing expression of meiosis associated genes at metaphase I phase were disclosed. Furthermore, the transcriptomic landscape of granulosa cells (GCs) surrounding oocytes from young and aged ovaries reveled that oocyte meiotic maturation was accompanied with a robust increased expression of genes involved with the mevalonate (MVA) pathway in GCs from young ovaries but these genes expression was not upregulated to counterpart level in GCs from aged ovaries.The inhibitor of MVA pathway of GCs, Statins significantly decreased polar body extrusion rate and increased the rate of irregularly assembled spindles and misaligned chromosomes remarkably in oocytes of culumus-oocyte complex (COCs) from young ovaries . Correspondingly, the activitor of MVA pathway of GCs, Geranylgeraniol ameliorated ovarian reserve and reduced meiotic defects in oocytes of COCs from aged ovaries. Mechanistically, MVA pathway activation in GCs culminated oocyte meiotic maturation by upregulating EGF signaling via LH receptor on GCs surrounding oocytes. Together, MVA pathway is a promising therapeutic target for prompting quality of oocytes from aged ovaries.
Project description:The reproductive lifespan in mammals is largely determined by the abundance and quality of oocytes residing within the primoridial ovarian follicular pool. Critical oocyte-expressed genes driving ovarian function have been identified, buta role for post-translational modifications, such as SUMOylation of these key factors is not well understood. Oocyte-specific genetic ablation of the sole E2 SUMOylation enzyme, UBC9, cause female sterility. Preantral and antral stage ovarian follicles are depleted by sexual maturity, and loss of the ovarian reserve in early adulthood causes premature ovarian failure, a condition associated with infertility in women. Gene expression changes indicate atered function of multiple POI candidate genes, including the transcription factors, NOBOX and SOHLH1. Together, these studies show that SUMOylation is required in the mammalian oocyte for regulating key genetic determinants of oocyte growth and differentiation.
Project description:Advanced age is a primary risk factor for female infertility due to reduced ovarian reserve and declining oocyte quality. However, as an important contributing factor, the role of metabolic regulation during reproductive aging is poorly understood. Here, we applied untargeted metabolomics to identify spermidine as a critical metabolite in ovaries to protect oocytes against aging. In particular, we found that spermidine level was reduced in aged ovaries and supplementation of spermidine promoted follicle development, oocyte maturation, early embryonic development and female fertility of aged mice. By micro-transcriptomic analysis, we further discovered that recovery of oocyte quality by spermidine was mediated by enhancement of mitophagy activity and mitochondrial function in aged mice, and this action mechanism was conserved in porcine oocytes under oxidative stress. Altogether, our findings demonstrate that spermidine supplementation is a potentially effective strategy to ameliorate oocyte quality and reproductive outcome of women at an advanced age.
Project description:During female reproductive life, the reserve of ovarian follicles is reduced by maturation and atresia until menopause ensues. Foxo3 is required to maintain the ovarian reserve in mice. We asked if overexpression of a constitutively active FOXO3 protein can increase long-lasting ovarian reproductive capacity in mice. Trangenic vs non-transgenic mice onto Foxo3+/- vs Foxo3-/- genotype
Project description:EXOSC10 is a catalytic subunit of the nuclear RNA exosome with an exoribonuclease activity. The enzyme processes and degrades different classes of RNAs. To delineate the role of EXOSC10 during oocyte growth, specific Exosc10 inactivation was performed in the oocytes from the primordial follicle stage onward using the Gdf9-iCre; Exosc10f/- mouse model (Exosc10cKO(Gdf9)). Exosc10cKO(Gdf9) female mice are infertile. The onset of puberty and the estrus cycle in mutants are initially normal and ovaries contain all follicle classes. By the age of eight weeks, vaginal smears reveal irregular estrus cycles and mutant ovaries display a complete depletion of follicles. Mutant oocytes retrieved from the oviduct are degenerated, sometimes showing an enlarged polar body which may reflect a defective first meiotic division. Under fertilization conditions, the mutant oocytes do not enter into an embryonic development process. Furthermore, we conducted a comparative proteome analysis of wild type and Exosc10 knockout mouse ovaries and identified EXOSC10-dependent proteins involved in many biological processes, such as meiotic cell cycle progression and oocyte maturation. Our results unambiguously demonstrate an essential role for EXOSC10 in oogenesis and may serve as a model for primary ovarian insufficiency in humans.