Project description:The success of human reproduction relies on high quality oocytes. Oocyte quality is manifested by the competence to complete meiosis, to be fertilized, and to support embryonic development. This meiotic and developmental competence is gradually established during the course of oocyte and follicle development, and is determined in large part by the autonomous gene expression program intrinsic to the oocyte. In order to explore the regulatory role of LSM14B in oocyte, we analyzed the effect of Lsm14b KO on gene expression in GV-stage fully-grown oocytes (FGOs) in mice by comparing the corresponding transcriptomes via RNA-Seq Analysis.
Project description:Vitrification cryopreservation of oocytes is an enabling technology for assisted reproductive technology. However, many factors in the vitrification process, such as the toxicity of cryoprotectant, osmotic stress, ice crystal formation during rewarming, will cause fatal damage to oocytes, thus affecting the embryo developmental potential and subsequent clinical outcomes. Therefore, oocyte vitrification still faces significant challenges. Recent studies have shown that LEA protein has the potential to improve oocyte cryopreservation, while the molecular mechanism by which it exerts protective effects is still unclear. Therefore, we have systematically investigated the effects of LEA proteins on the vitrification cryopreservation and their molecular mechanisms. Results revealed that the proteins improved the developmental potential of human oocytes following cryopreservation, mostly by downregulating FOS genes and reducing oxidative stress. Moreover, the synergistic cryoprotection of LEA proteins by inhibiting the formation of ice crystals was given full play. This study provides a new strategy for high-quality cryopreservation of human oocytes.
Project description:The present study was undertaken to discover molecular markers in bovine cumulus cells predictive of oocyte competence and elucidate their functional significance. Differences in RNA transcript abundance in cumulus cells harvested from oocytes of adult versus prepubertal animals (model of poor oocyte quality) were identified by microarray analysis. Four genes of interest encoding for the lysosomal cysteine proteinases cathepsin B, S, K and Z and displaying greater transcript abundance in cumulus cells surrounding oocytes harvested from prepubertal animals were chosen for further investigation. Greater mRNA abundance for such genes in cumulus cells of prepubertal oocytes was confirmed by real time RT-PCR. Elevated transcript abundance for cathepsins B, S and Z was also observed in cumulus cells surrounding adult metaphase II oocytes that developed to the blastocyst stage at a low percentage following parthenogenetic activation, versus those that developed at a high percentage. Functional significance of cumulus cell cathepsin expression to oocyte competence was confirmed by treatment of cumulus oocyte complexes during in vitro oocyte maturation with a cell permeable cysteine proteinase (cathepsin) inhibitor. Inhibitor treatment decreased apoptotic nuclei in the cumulus layer and enhanced development of parthenogenetically activated and in vitro fertilized adult oocytes to the blastocyst stage. Stimulatory effects of inhibitor treatment during meiotic maturation on subsequent embryonic development were not observed when oocytes were matured in the absence of cumulus cells. Results support a functional role for cumulus cell cathepsins in compromised oocyte competence and suggest that cumulus cell cathepsin mRNA abundance may be predictive of oocyte quality. Keywords: Bovine, microarray, cDNA, cumulus cells
Project description:EHMT1 (also known as GLP) is a multifunctional protein, best known for its role as an H3K9me1 and H3K9me2 methyltransferase through its reportedly obligatory dimerization with EHMT2 (also known as G9A). Here, we investigated the role of EHMT1 in the oocyte in comparison to EHMT2 using oocyte-specific conditional knockout mouse models (Ehmt2 cKO, Ehmt1cKO, Ehmt1/2 cDKO), with ablation from the early phase of oocyte growth. Loss of EHMT1 in Ehmt1 cKO and Ehmt1/2 cDKO oocytes recapitulated meiotic defects observed in the Ehmt2 cKO; however, there was a significant impairment in oocyte maturation and developmental competence in Ehmt1 cKO and Ehmt1/2 cDKO oocytes beyond that observed in the Ehmt2cKO. Consequently, loss of EHMT1 in oogenesis results, upon fertilization, in mid-gestation embryonic lethality. To identify H3K9 methylation and other meaningful biological changes in each mutant to explore the molecular functions of EHMT1 and EHMT2, we performed immunofluorescence imaging, multi-omics sequencing, and mass spectrometry (MS)–based proteome analyses in cKO oocytes. Although H3K9me1 was depleted only upon loss of EHMT1, H3K9me2 was decreased, and H3K9me2-enriched domains were eliminated equally upon loss of EHMT1 or EHMT2. Furthermore, there were more significant changes in the transcriptome, DNA methylome, and proteome in Ehmt1/2 cDKO than Ehmt2 cKO oocytes, withtranscriptional derepression leading to increased protein abundance and local changes in genic DNA methylation in Ehmt1/2 cDKO oocytes. Together, our findings suggest that EHMT1 contributes to local transcriptional repression in the oocyte, partially independent of EHMT2, and is critical for oogenesis and oocyte developmental competence
Project description:The present study was undertaken to discover molecular markers in bovine cumulus cells predictive of oocyte competence and elucidate their functional significance. Differences in RNA transcript abundance in cumulus cells harvested from oocytes of adult versus prepubertal animals (model of poor oocyte quality) were identified by microarray analysis. Four genes of interest encoding for the lysosomal cysteine proteinases cathepsin B, S, K and Z and displaying greater transcript abundance in cumulus cells surrounding oocytes harvested from prepubertal animals were chosen for further investigation. Greater mRNA abundance for such genes in cumulus cells of prepubertal oocytes was confirmed by real time RT-PCR. Elevated transcript abundance for cathepsins B, S and Z was also observed in cumulus cells surrounding adult metaphase II oocytes that developed to the blastocyst stage at a low percentage following parthenogenetic activation, versus those that developed at a high percentage. Functional significance of cumulus cell cathepsin expression to oocyte competence was confirmed by treatment of cumulus oocyte complexes during in vitro oocyte maturation with a cell permeable cysteine proteinase (cathepsin) inhibitor. Inhibitor treatment decreased apoptotic nuclei in the cumulus layer and enhanced development of parthenogenetically activated and in vitro fertilized adult oocytes to the blastocyst stage. Stimulatory effects of inhibitor treatment during meiotic maturation on subsequent embryonic development were not observed when oocytes were matured in the absence of cumulus cells. Results support a functional role for cumulus cell cathepsins in compromised oocyte competence and suggest that cumulus cell cathepsin mRNA abundance may be predictive of oocyte quality. Keywords: Bovine, microarray, cDNA, cumulus cells Differences in RNA transcript abundance in cumulus cells harvested from oocytes of adult versus prepubertal animals (model of poor oocyte quality) were identified by microarray analysis. Total RNA from pools of cumulus cells (n = 4) collected from adult and prepubertal animals for microarray experiments was amplified. Two color microarray experiments were conducted using a bovine cDNA array containing expressed sequence tags (ESTs) representing approximately 15200 unique genes. Hybridizations were performed on duplicate slides (prepubertal versus adult) and incorporated a dye swap. The total number of slides used is eight.
Project description:The cumulus cells (CCs) that envelope antral and ovulated oocytes have been regarded as putative source of non-invasive markers of the oocyte developmental competence and a number of studies have observed a correlation between CCs gene expression, embryo quality and final pregnancy outcome. With the aim of identifying marker transcripts, we isolated CCs from antral mouse oocytes of known developmental incompetence (NSN-CCs) or competence (SN-CCs) and compared their transcriptomes.
Project description:Oocyte maturation is vital to attain full competence required fertilization and embryogenesis. As a maternal effect factor, NLRP14 is preferentially expressed in mammalian oocytes and early embryos. Yet the role and molecular mechanism of NLRP14 in oocyte maturation and early embryogenesis is largely unknown. Whether NLRP14 deficiency accounts for human infertility with oocyte and embryo defects remains to be elucidated. Here, NLRP14 is identified essential for establishment of competent oocytes that can sustain early embryo development. Maternal deficiency of Nlrp14 results in sterility characterized by oocyte maturation defects and early embryo arrest. Nlrp14 ablation leads to compromised oocyte quality and developmental competence due to impaired oocyte cytoplasmic and nuclear maturation. Mechanistically, NLRP14 interacts with UHRF1 in oocyte cytoplasm to protect it from proteasome-dependent degradation, and perturbs maternal mRNA zygotic-decay and zygotic genome activation during maternal-zygotic transition. Furthermore, compound heterozygous pathogenic variants in NLRP14 gene are identified in infertile women with early embryonic arrest, which interrupt the NLRP14-UHRF1 interaction or UHRF1 protein expression. Our data uncover a vital role of NLRP14 as a new cytoplasmic-specific modulator of UHRF1 in oocyte meiotic maturation and early embryogenesis, which should provide new insights into risk prediction and genetic diagnosis for female infertility.
Project description:Reproductive aging is a major cause of fertility decline, attributed to decreased oocyte quantity and competence. Follicular somatic cells play crucial roles in the growth and development of the oocyte by providing nutrients and regulatory factors. Here we investigated how oocyte quality is affected by its somatic cell environment by creating chimeric follicles, whereby an oocyte from one follicle was transplanted into and cultured within another follicle whose native oocyte was removed. Somatic cells within the chimeric follicle re-establish connections with the oocyte and support oocyte growth and maturation in a three-dimensional (3D) culture system. We show that young oocytes transplanted into aged follicles exhibited reduced meiotic maturation and developmental potential, whereas the young follicular environment significantly improved the rates of maturation, blastocyst formation and live birth of aged oocytes. Aged oocytes cultured within young follicles exhibited enhanced interaction with somatic cells, more youth-like transcriptome, remodelled metabolome, improved mitochondrial function, and enhanced fidelity of meiotic chromosome segregation. These findings provide the basis for a future follicular somatic cell-based therapy to treat age-associated female infertility.
Project description:Somatic cells surrounding the oocyte were sampled at the following stages: developmentally incompetent or poorly competent prophase I oocytes (NC1 oocytes), developmentally competent prophase I oocytes (C1 oocytes), and developmentally competent metaphase II oocytes (C2 oocytes). NC1 samples were collected from late vitellogenic females (LV), C1 samples from post-vitellogenic females (PV), and C2 samples from females undergoing meiotic maturation (Germinal Vesicle Breakdown) Global transcriptional profiling was performed using somatic cells collected from rainbow trout ovarian follicles during in vivo oocyte developmental competence acquisition. Somatic cells were collected at 3 stages of oogenesis: NC1 stage follicles (LV, late vitellogenic, prophase I arrested oocytes, meiotically incompetent and developmentally incompetent, n=6), C1 stage follicles (PV, post-vitellogenic, prophase I arrested oocytes, meiotically competent and developmentally competent, n=16). Ovulatory follicles were also collected during oocyte maturation after in vivo induction (metaphase II arrested oocytes, developmentally fully competent, n=6).