Project description:Vitrification is increasingly used to cryopreserve gametes and embryos in assisted reproductive technology (ART). Our prior research demonstrates that vitrification preserves the viability and functionality of ovarian follicles. However, its impact on follicle-enclosed oocyte remains unknown. The current study investigates whether vitrification, combined with a 3D encapsulated in vitro follicle growth (eIVFG) system, maintains oocyte transcriptome during in vitro follicle development and oocyte maturation. Immature mouse preantral follicles were vitrified and cultured in eIVFG for 8 days to grow to the preovulatory stage, followed with the induction of ovulation and oocyte maturation on day 9, with fresh follicles as the control. Oocytes at germinal vesicle (GV) stage from grown preovulatory follicles on day 8 and oocytes at metaphase II (MII) upon ovulation on day 9 were collected for single-oocyte Smart-Seq2 RNA sequencing analysis. The principal component analysis (PCA) separated GV and MII oocytes into two distinct clusters, but oocytes from fresh and vitrified follicles were largely overlapped. Differential gene expression (DEG) analysis revealed that GV or MII oocytes from fresh and vitrified follicles had comparable expression of maternal effect genes and other genes related to oocyte meiotic and developmental competence. There was a significant transcriptomic change during the GV-to-MII transition. Gene ontology (GO) and KEGG analysis identified DEGs between GV and MII oocytes related to cell cycle, RNA processing, mitochondria, and ribosome. In summary, our study demonstrates that vitrification preserves oocyte transcriptome during in vitro follicle development and oocyte maturation, supporting its potential in fertility preservation. Moreover, our single-oocyte RNA sequencing analysis identifies key DEGs upon GV-to-MII transition, indicating their potential functions in underpinning oocyte meiotic and developmental competence.
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:In vitro maturation (IVM) of oocytes retrieved from ovum pick-up (OPU) or ovarian tissue (OT) is a standard approach for patients with specific conditions where prior hormonal stimulation is contraindicated. However, the developmental competence of oocytes matured in vitro is still inferior to that of oocytes matured in vivo. Capacitation-IVM (CAPA-IVM) includes an extra step of pre-maturation culture (PMC) with c-type natriuretic peptide (CNP) as a meiotic arrestor to better synchronize cytoplasmic and nuclear maturity in oocytes. This study aims to evaluate the effect of CAPA-IVM on equine oocyte quality and developmental competence. Immature cumulus-oocyte complexes (COCs) were retrieved from slaughterhouse ovaries and matured in vitro either in CAPA-IVM (short or long) or standard IVM. Matured oocytes from each group were analyzed for calcium-releasing potential and single-oocyte proteomics, and embryo development was assessed after fertilization with Piezo-drilled intracytoplasmic sperm injection (ICSI). Genetic analysis of developed blastocysts was performed to detect chromosomal aberrations. Our findings demonstrate that CAPA-IVM of equine COCs yields significantly higher maturation rates than controls. Moreover, short CAPA-IVM with six hours pre-maturation culture showed substantially higher embryo development potential than the control group. Genetic analysis revealed a high euploidy rate in equine blastocysts regardless of the maturation conditions. Live calcium imaging of the fertilized oocytes demonstrated the majority of oocytes with non-continuous calcium oscillation patterns, irrespective of maturation conditions. Single oocyte proteomics reveals a comparable proteomic landscape between matured oocytes from short CAPA-IVM and standard IVM. However, a trend of differential expression was observed in specific proteins related to cytoskeleton, cell cycle, and hemostasis in the short CAPA-IVM group. Our findings indicate that CAPA-IVM holds the potential to improve oocyte quality and competence in horses. However, further fine-tuning of culture conditions based on omics analysis would benefit the effective use of these IVM systems. Moreover, given that the mare serves as an excellent model for human reproduction, the molecular trends identified in this study could provide valuable insights for advancing human artificial reproductive technologies.
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:Oocyte vitrification is an important assisted reproductive technology (ART) that preserves the fertility of unmarried patients with malignant tumors before radiotherapy and chemotherapy, cases where no sperm are available on ART oocyte collection day, and the development of the oocyte donation program. In recent years, the effects of ART, including the vitrification of oocytes and embryos on the health of offspring, have attracted much attention; however, it is difficult to conduct long-term follow-up and biochemical evaluation in humans. In this study, we detected the effect of oocyte vitrification on gene expression in the organs of adult mice offspring by RNA-sequencing for the first time. Our results showed that only a small amount of gene expression was affected. Seven genes (Tpm3, Hspe1-rs1, Ntrk2, Cyp4a31, Asic5, Cyp4a14, Retsat) were abnormally expressed in the liver, and ten genes (Lbp, Hspe1-rs1, Prxl2b, Pfn3, Gm9008, Bglap3, Col8a1, Hmgcr, Ero1lb, Ifi44l) were abnormal in the kidney. Several genes were related to metabolism and disease occurrence in the liver or kidney. Besides, we paid special attention to the expression of known imprinted genes and DNA methylation-related genes in adult organs, which are susceptible to oocyte cryopreservation only in the preimplantation stage. As a result, some of these transcripts were detected in the liver and kidney, but they were not affected by oocyte vitrification. In conclusion, we first report that oocyte vitrification did not significantly change the global gene expression in offspring organs, including imprinted genes and DNA methylation-related genes; nonetheless, it can still influence the transcription of a few functional genes. The potential adverse effects caused by oocyte vitrification need attention and further study.
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.