BCAS2 regulates oocyte meiosis by participating in alternative mRNA splicing
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE228983 | GEO | 2024/01/01
REPOSITORIES: GEO
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Project description:Granulosa cell proliferation and differentiation are essential for follicle development. Breast cancer amplified sequence 2 (BCAS2) is necessary for spermatogenesis, oocyte development, and maintaining the genome integrity of early embryos in mice. However, the function of BCAS2 in granulosa cells is still unknown. We show that conditional disruption of BCAS2 causes follicles development failure; cell proliferation markers PCNA and Ki67 positive cell ratio are unchanged in granulosa cells. However, specific deletion of BCAS2 causes BrdU positive cell ratio to decrease, cell cycle arrest appearance, DNA damage, and cell apoptosis increase in granulosa cells, RPA1 was abnormally stained in granulosa cells. Furthermore, RNA-Seq results reveal that knockout of BCAS2 results in cellular senescence gene unusual expression. BCAS2 participates in the PRP19 complex to mediate alternative splicing (AS) of E2f3 and Flt3l mRNA to inhibit the cell cycle. Knock down of BCAS2 results in a significantly decrease of BrdU positive cell ratio in Human granulosa-like tumor(KGN) cell line. Thus, BCAS2 regulates granulosa cell proliferation, DNA damage repair, and cell apoptosis. BCAS2 is vital for female fertility.
2023-06-01 | GSE218919 | GEO
Project description:BCAS2 regulates oocyte meiosis by participating in alternative mRNA splicing
| PRJNA952271 | ENA
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.
2025-04-02 | GSE292062 | GEO
Project description:Understanding the intricacies of homologous recombination during meiosis is crucial for reproductive biology. However, the role of alternative splicing (AS) in DNA double-strand breaks (DSBs) repair and synapsis remains elusive. In this study, we investigated the impact of conditional knockout (cKO) of the splicing factor gene Bcas2 in mouse germ cells, revealing impaired DSBs repair and synapsis, resulting in non-obstructive azoospermia (NOA). Employing crosslinking immunoprecipitation and sequencing (CLIP-seq), we globally mapped BCAS2 binding sites in the testis, uncovering its predominant association with 5' splice sites (5'SS) of introns and a preference for GA-rich regions. Integrating CLIP-seq with RNA-seq, we identified BCAS2 as a key player in the AS of pre-mRNAs, including Spo11, Six6os1, Sycp1, Msh5, Cdk2, Sun2, Stag3, and Spdya, crucial for DSBs repair and synapsis. Notably, BCAS2 exhibited direct binding and regulatory influence on Trp53bp1 and Six6os1 through AS, unveiling novel insights into DSBs repair and synapsis during meiotic prophase I. Furthermore, the interaction between BCAS2, hnRNPH1, and SRSF3 was discovered to orchestrate Trp53bp1 expression via AS, underscoring its role in meiotic prophase I DSBs repair. In summary, our findings delineate the indispensable role of BCAS2-mediated post-transcriptional regulation in DSBs repair and synapsis during male meiosis. This study provides a comprehensive framework for unraveling the molecular mechanisms governing the post-transcriptional network in male meiosis, contributing to the broader understanding of reproductive biology.
2024-03-25 | GSE254463 | GEO
Project description:Understanding the intricacies of homologous recombination during meiosis is crucial for reproductive biology. However, the role of alternative splicing (AS) in DNA double-strand breaks (DSBs) repair and synapsis remains elusive. In this study, we investigated the impact of conditional knockout (cKO) of the splicing factor gene Bcas2 in mouse germ cells, revealing impaired DSBs repair and synapsis, resulting in non-obstructive azoospermia (NOA). Employing crosslinking immunoprecipitation and sequencing (CLIP-seq), we globally mapped BCAS2 binding sites in the testis, uncovering its predominant association with 5' splice sites (5'SS) of introns and a preference for GA-rich regions. Integrating CLIP-seq with RNA-seq, we identified BCAS2 as a key player in the AS of pre-mRNAs, including Spo11, Six6os1, Sycp1, Msh5, Cdk2, Sun2, Stag3, and Spdya, crucial for DSBs repair and synapsis. Notably, BCAS2 exhibited direct binding and regulatory influence on Trp53bp1 and Six6os1 through AS, unveiling novel insights into DSBs repair and synapsis during meiotic prophase I. Furthermore, the interaction between BCAS2, hnRNPH1, and SRSF3 was discovered to orchestrate Trp53bp1 expression via AS, underscoring its role in meiotic prophase I DSBs repair. In summary, our findings delineate the indispensable role of BCAS2-mediated post-transcriptional regulation in DSBs repair and synapsis during male meiosis. This study provides a comprehensive framework for unraveling the molecular mechanisms governing the post-transcriptional network in male meiosis, contributing to the broader understanding of reproductive biology.
2024-03-25 | GSE254462 | GEO
Project description:BCAS2 (Breast cancer amplified sequence 2) is involved in multiple biological processes, including pre-mRNA splicing. However, the physiological roles of BCAS2 are still largely unclear. Here we report that BCAS2 is specifically enriched in spermatogonia of mouse testes. Conditional disruption of Bcas2 in male germ cells impairs spermatogenesis and leads to male mouse infertility. Although the spermatogonia appear grossly normal, spermatocytes in meiosis prophase I and meiosis events (recombination and synapsis) are rarely observed in the BCAS2-depleted testis. In BCAS2 null testis, 245 genes are altered in alternative splicing forms; at least three spermatogenesis-related genes (Dazl, Ehmt2 and Hmga1) can be verified. In addition, disruption of Bcas2 results in a significant decrease of the full-length form and an increase of the short form (lacking exon 8) of DAZL protein. Altogether, our results suggest that BCAS2 regulates alternative splicing in spermatogonia and the transition to meiosis initiation, and male fertility.
2016-11-15 | GSE89801 | GEO
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.
2024-07-22 | GSE270016 | GEO
Project description:Primordial follicles are the first class of follicles formed in the mammalian ovary and are comprised of an oocyte surrounded by a layer of squamous pre-granulosa cells. This developmental class remains in a non-growing state until individual follicles activate to initiate folliculogenesis. What regulates the timing of follicle activation and the upstream signals that govern these processes are major unanswered questions in ovarian biology. This is partly due to the paucity of data on staged follicle cells since isolating and manipulating individual oocytes and somatic cells from early follicle stages are challenging. To date, most studies on isolated primordial follicles have been conducted on cells collected from animal-age- or oocyte size-specific samples, which encompass multiple follicular stages. Here, we report a method for collecting primordial follicles and their associated oocytes and somatic cells from neonatal murine ovaries using liberase, DNase I, and Accutase. This methodology allows for the identification and collection of follicles immediately post-activation enabling unprecedented interrogation of the primordial-to-primary follicle transition. Molecular profiling by single-cell RNA sequencing (scRNA-seq) revealed that processes including organelle disassembly and cadherin binding were enriched in oocytes and somatic cells as they transitioned from primordial to the primary follicle stage. Furthermore, targets including WNT4, TGFβ, FOXO3, and a network of transcription factors were identified in the transitioning oocytes and somatic cells as potential upstream regulators that collectively may drive follicle activation. Taken together, we have developed a more precise characterization and selection method for studying staged-follicle cells, revealing several novel regulators of early folliculogenesis.
2022-06-29 | GSE206681 | GEO
Project description:Oocyte competence for early embryo development relies on intercellular communication between the maturing oocyte and preovulatory follicle. Preovulatory follicle maturity, as indicated by serum estradiol concentration or follicle diameter, has previously been linked to pregnancy, follicular fluid metabolites, cumulus-oocyte metabolism, and oocyte competency for embryo development. Such relationships indicate metabolic and developmental programming of the oocyte based on the preovulatory follicle’s physiological status, but downstream impacts on the molecular signature of blastocysts have not been examined. We hypothesized that supplementing maturing oocytes with follicular fluid originating from preovulatory follicles of greater or lesser maturity would impact the transcriptome of resulting blastocysts and indicate metabolic programming of the embryo that originated from the oocyte’s maturation environment. The objective was to investigate the effect of follicle maturity on metabolic preparation of the oocyte by examining the functional genome of blastocysts originating from oocytes matured in the presence of follicular fluid from preovulatory follicles of greater or lesser maturity. In vitro maturing oocytes were supplemented with follicular fluid collected from preovulatory follicles of greater or lesser maturity. Following identical embryo culture procedures, RNA-sequencing was performed on pools of 2 blastocysts (Greater, n = 12; Lesser, n = 15; all with stage code = 7 and quality code = 1). A total of 12,310 gene transcripts were identified in blastocysts after filtering to remove lowly abundant transcripts. There were 113 transcripts that differed in abundance between blastocysts originating from oocytes matured in greater versus lesser maturity follicular fluid (eFDR < 0.01). Although no pathways were significantly enriched with differentially abundant transcripts, transcriptome profiles suggested improved Wnt/β-catenin signaling, metabolism, and protection from oxidative stress in blastocysts derived from oocytes matured in greater maturity follicular fluid, while unregulated cell growth presented in blastocysts resulting from the lesser follicle maturity treatment.
2024-10-22 | GSE279311 | GEO
Project description:Purpose: Preovualtory follicle diameter influences embryo quality in beef cattle that rely on a gonadotropin releasing hormone (GnRH) injection to induce the preovualtory gonadotropin surge and subsequent ovualtion. The goals of this study are to compare transcriptome profiles of pools of four oocytes or associated cumulus cells collected from small (≤11.7mm) and large follicles (≥12.7 mm) exposed to a GnRH-induced gonadotropin surge and follicles (11.7-14.0 mm) exposed to an endogenous gonadotropin surge (spontaneous follicles). Methods: Oocyte and cumulus cell mRNA profiles of pools of four oocytes or associated cumulus cells collected from small (≤11.7mm) and large follicles (≥12.7 mm) exposed to a GnRH-induced gonadotropin surge or spontaneous follicles (11.7-14.0 mm) which were exposed to an endogenous gonadotropin surge were generated by deep sequencing (n=6 small follicle oocyte, 6 small follicle cumulus, 6 large follicle oocyte, 6 large follicle cumulus, 4 spontaneous follcile oocyte, and 5 spontaneous follicle cumulus pools), using Illumina HiSeq 2000 . The sequence reads that passed quality filters were aligned to the Bos taurus reference genome UMD3.1 using Hisat2mapper. FeatureCounts was used to quantify transcript abundance in each library using Bos taurus gene annotation from Ensembl. Differences in gene transcript expression were then analyzed amoung oocyte or cumulus cell follcile classifications using the packages edgeR and DESeq2 in R software. Results: We mapped an average of 30 million sequence reads per sample to the Bos taurus reference genome UMD3.1 and identified 69, 94, and 83 differentially expressed gene transcripts (DEG) among oocyte libraries from small versus large, small versus spontaneous, and large versus spontaneous follicle classifications, respectively. We also identified 128, 98, and 80 DEG among cumulus cell libraries from small versus large, small versus spontaneous, and large versus spontaneous follicles, respectively. Conclusions: Our study represents detailed analysis of RNA-sequencing data generated from in vivo produced cumulus and oocyte samples collected from preovualtory follicles of varied physiological status after exposure to an endogenous or exogenously stimulated gonadotropin surge. The results of our study highlight key differences in the transcriptome of samples from small, large, or spontaneous follicles and provide insight into the reduced embryo quality observed when small follicles undergo a GnRH induced gonadotropin surge.
2021-06-08 | GSE176344 | GEO