Project description:Protein composition of human ovarian follicular fluid (FF) constitutes the microenvironment for oocyte development. Several proteomics studies of FF from pre-ovulatory follicles have revealed insights on oocyte maturation, however, there is a lack of knowledge on changes produced at protein levels in the FF of human small antral follicles (hSAF) related to the upcoming oocyte maturation. Using mass spectrometry-based proteomics, we evaluated the protein composition of FF that surrounds oocytes capable to reach metaphase II (MII) after IVM with the protein profile of FF that surrounds immature oocytes. The samples were collected from small antral follicles (size 6.0 ± 1.5 mm) extracted from six women, from which two or three samples were extracted. The comparison was based on both, a multivariate (sPLS-DA) and univariate analyses (t-test).
Project description:The antral follicle stage plays a crucial role in mammalian oocyte maturation, signifying the final stages of oocyte development and ovulation. This complex process relies on synchronized interactions between oocyte maturation and the proliferation of neighboring granulosa cells. Previous studies have identified two subtypes of granulosa cells in antral follicles: cumulus granulosa cells, located in the inner region, which surround and support the oocyte, and mural granulosa cells, present in the outer layers, which provide mechanical support to the follicular wall and possess steroidogenic functions. Despite the wealth of molecular data generated by these studies, many fundamental questions regarding key developmental events, granulosa cell heterogeneity, functional annotation, and the intricate relationship between somatic cells and oocytes still lack detailed, single-cell resolution-level investigations. In this study, we isolated follicular cells from porcine antral follicles and conducted scRNA-seq to analyze the single-cell transcriptomes of these cells. By identifying and sub-clustering ovarian cells, such as mural granulosa cells and cumulus granulosa cells, we elucidated the heterogeneity of granulosa cells in pigs.
Project description:The molecular mechanisms controlling the transition from meiotic arrest (germinal vesicle stage) to meiotic resumption (germinal vesicle breakdown stage) in mammalian oocytes have not been fully elucidated. Single-cell omics technology provides a new opportunity to decipher the early molecular events of oocyte maturation in mammals. Here we focused on analyzing oocytes that are collected from antral follicles of porcine puberty ovary. We used single-cell M&T-seq technology to analyze the nuclear DNA methylome and cytoplasmic transcriptome in parallel for 62 oocytes. We developed a package of pipelines for single-cell methylomics analysis, namely methyConcerto, to specifically and comprehensively characterize the methylation state and allele-specific methylation events for a single cell. We also performed 10X Genomics single-cell transcriptomic analyses to explore the bi-directional cell-cell communications within antral follicles. We characterized the gene expression and DNA methylation programs of individual oocytes in porcine antral follicle, thereby enabled defining two distinct types of oocytes, one of which is significantly more poised for maturation. Significantly differentially expressed or allele-specifically methylated genes were enriched in “RNA metabolism”, “oocyte meiosis” important signaling pathways, e.g., HIF-1/Ras/mTOR/Phospholipase D/ErbB signaling pathways etc. These results are in concert with the cellular communication results. We further confirmed Insulin Receptor Substrate-1 (IRS-1) in insulin signaling pathway is a key regulator of germinal vesicle stage oocyte maturation by in vitro maturation experiments. Our study provides new insights into the regulatory mechanisms between meiotic arrest and meiotic resumption in mammalian oocytes. We also provide a new analytical package for future single-cell methylomics study.
Project description:The molecular mechanisms controlling the transition from meiotic arrest (germinal vesicle stage) to meiotic resumption (germinal vesicle breakdown stage) in mammalian oocytes have not been fully elucidated. Single-cell omics technology provides a new opportunity to decipher the early molecular events of oocyte maturation in mammals. Here we focused on analyzing oocytes that are collected from antral follicles of porcine puberty ovary. We used single-cell M&T-seq technology to analyze the nuclear DNA methylome and cytoplasmic transcriptome in parallel for 62 oocytes. We developed a package of pipelines for single-cell methylomics analysis, namely methyConcerto, to specifically and comprehensively characterize the methylation state and allele-specific methylation events for a single cell. We also performed 10X Genomics single-cell transcriptomic analyses to explore the bi-directional cell-cell communications within antral follicles. We characterized the gene expression and DNA methylation programs of individual oocytes in porcine antral follicle, thereby enabled defining two distinct types of oocytes, one of which is significantly more poised for maturation. Significantly differentially expressed or allele-specifically methylated genes were enriched in “RNA metabolism”, “oocyte meiosis” important signaling pathways, e.g., HIF-1/Ras/mTOR/Phospholipase D/ErbB signaling pathways etc. These results are in concert with the cellular communication results. We further confirmed Insulin Receptor Substrate-1 (IRS-1) in insulin signaling pathway is a key regulator of germinal vesicle stage oocyte maturation by in vitro maturation experiments. Our study provides new insights into the regulatory mechanisms between meiotic arrest and meiotic resumption in mammalian oocytes. We also provide a new analytical package for future single-cell methylomics study.
Project description:Follicles of polycystic ovaries (PCO) often become arrested in early antral stages at around 3 to 11 mm in diameter. The condition disturbs dominant follicle selection and may result in altered ovulation and anovulation. During the growth and development of human follicles, the follicular fluid (FF) constitutes the avascular microenvironment in which the oocyte develops and acts as a vehicle for hormone signaling between cues from circulation and follicular cells. Previous proteomics studies performed on FF from women with polycystic ovarian syndrome (PCOS) have revealed information on the protein changes associated with the pathophysiology of this disorder. However, these studies have been conducted on FF samples obtained in connection with oocyte pick-up during ovarian stimulation right at the time of ovulation and are limited to follicular conditions during the follicular phase of the menstrual cycle. This study aimed to detect proteomic alterations in FF from human small antral follicles (hSAF) obtained from women with PCO as compared to normal women.
Project description:Human ovarian folliculogenesis is an highly regulated and complex process. Characterization of follicular cell signatures during this dynamic process is important to understand follicle fate (to grow, become dominant or undergo atresia). The transcriptional signature of human oocytes and granulosa cells (GC) in early-growing and ovulatory follicles have been previously described, however that of oocytes with surrounding GCs in small antral follicles have not been studied yet. Here, we have generated a unique dataset of single-cell transcriptomics (SmartSeq2) consisting of the oocyte with surrounding GCs from several individual (non-dominant) small antral follicles isolated from adult human ovaries. We have identified two main types of (healthy) follicles, with a distinct oocyte and GC signature. Using the CellphoneDB algorithm, we then investigated the bi-directional ligand-receptor interactions regarding the TGFβ/BMP, WNT, NOTCH, and receptor tyrosine kinases (RTK) signaling pathways between oocyte and GCs within each antral follicle type. Our work not only revealed the diversity of small antral follicles but also contributes to fill the gap in mapping the molecular landscape of human folliculogenesis and oogenesis.
Project description:Dibutyl phthalate (DBP), di-2-ethylhexyl phthalate (DEHP), and benzyl butyl phthalate (BBP) are three phthalates commonly found in consumer products, including the plastic coating of pharmaceuticals and personal care products. Folliculogenesis, a tightly regulated process occurring in the ovary, is the maturation of an immature primordial follicle to a mature antral follicle. Follicles house the oocyte and antral follicles specifically play a crucial role in ovarian steroidogenesis and ovulation. DBP, BBP, and DEHP have been associated with inhibited antral follicle growth in vitro, decreased ovulation rates in vitro, and decreased antral follicle counts in women. However, little is known about the effects of a three-phthalate mixture on antral follicles in vivo. The objective of this study was to evaluate the effects of a human relevant mixture of DBP, BBP, and DEHP on ovarian follicles through proteome profiling analysis. CD-1 female mice (60 days old) were pipet fed tocopherol stripped corn oil (vehicle control) only or a phthalate mixture (52% DBP, 36% DEHP, and 12% BBP dissolved in vehicle) which modeled human follicular fluid concentrations. The mice were treated with 32µg/kg/day (PHT Mix 32; cumulative estimate in general population) and 500µg/kg/day (PHT Mix 500; cumulative estimate in occupationally exposed individuals) for 10 consecutive days. Proteome profiling of antral follicles (>250µm) was performed via label-free tandem mass spectrometry. A total of 5,417 antral follicle proteins were identified in the three groups, of which 194 were differentially abundant between the vehicle and PHT Mix 32 group, and 136 between the vehicle and PHT Mix 500 group. Gene ontology analysis revealed that the two treatments of the phthalate mixture upregulate and downregulate distinctive processes, supporting non-monotonic effects of phthalates on the antral follicle proteome. Taken together, these results reveal that a human relevant mixture of DBP, BBP, and DEHP alters the antral follicle proteome and merits further evaluation to elucidate the molecular mechanisms by which phthalates cause negative reproductive outcomes.
Project description:Cumulus cells (CCs) and mural granulosa cells (MGCs) have different phenotypes and different roles in the follicle. However, our previous reports have suggested that CCs and MGCs from bovine early antral follicles become MGC-like cells and CC-like cells, respectively. In this study, we examined whether granulosa cells (GCs) from secondary follicles and MGCs from late antral follicles were able to reconstruct complexes with transzonal projection (TZP)-free denuded oocytes (DOs) and regenerate TZPs similar to MGCs from early antral follicles. Furthermore, to confirm that the regenerated TZPs were functional, the development of reconstructed complexes and oocyte growth in the complexes were determined. After coculture, GCs were able to reconstruct complexes with DOs and regenerate TZPs similar to MGCs from early antral follicles. In addition, the oocytes in integrally reconstructed complexes grew fully and acquired meiotic competence, suggesting that the regenerated TZPs are functional. In contrast, MGCs from late antral follicles had lost the ability to elongate TZPs. Since the ability to regenerate TZPs differed among the cells, the transcriptome was analyzed among GCs, CCs, and MGCs collected from follicles of different sizes. The characteristic of TZP generation coincided with transcriptome changes in two directions from GCs to CCs and MGCs. In conclusion, until the early antral follicle stage, bovine GCs, CCs, and MGCs have common characteristics to elongate TZPs and form antrum-like structures to support oocyte growth in vitro. Furthermore, as the follicle develops, MGCs lose the ability to elongate TZPs.