Project description:Our aim is to characterize the role of the TBP2 protein during the growth of the oocyte. To that aim, we analyzed by RNA-seq the transcriptome of primary oocytes from wild type and Tbp2 null ovaries at the primary (post natal day 7) and secondary follicular stage (post natal day 14).
Project description:Growing mammalian oocytes accumulate substantial amounts of RNA, most of which are degraded during the subsequent maturation stage. The growth-to-maturation transition begins with germinal vesicle breakdown (GVBD, envisioned as nuclear envelope breakdown) and is critical for oocyte quality. However, the concomitant changes in the transcriptome during GVBD as well as the underlying machinery remained unclear. Here, we report that an RNA exosome-associated RNase, EXOSC10, sculpts the transcriptome at multiple level to facilitate the oocyte growth-to-maturation transition. We establish an oocyte-specific knockout of Exosc10 in mice using CRISPR/Cas9 and find female subfertility due to failed GVBD. By performing single oocyte RNA-seq in different ways, we document dysregulated transcriptomes, unsuccessfully processed rRNAs in mutant oocytes, and many up-regulated RNAs that encode proteins important for endomembrane trafficking, meiotic cell cycle and RNA metabolism. EXOSC10-depleted oocytes have impaired endomembrane components including endosome, lysosome, ER and Golgi. In addition, CDK1 fails to be activated possibly due to persistent WEE1 activity, which blocked lamina phosphorylation and disassembly in mutant oocytes. Collectively, we propose that EXOSC10 promotes the growth-to-maturation transition in mouse oocytes by degrading mRNAs that encode growth-phase factors and sculpting the transcriptome to support the maturation phase of oogenesis.
Project description:Mammalian follicle development is characterised by extensive changes in morphology, endocrine responsiveness, and function, providing the optimum environment for oocyte growth, development, and resumption of meiosis. In cattle, the first signs of transcription activation in the oocyte are observed in the secondary follicle, later than during mouse and human oogenesis. While many studies have generated extensive datasets characterising gene expression in bovine oocytes, they are mostly limited to the analysis of fully grown and matured oocytes. The aim of the present study was to apply single-cell RNA sequencing to interrogate the transcriptome of the growing bovine oocyte from the secondary follicle stage through to the mid-antral follicle stage. Single-cell RNA-seq libraries were generated from oocytes of known diameters (<60 to >120 um), and datasets were binned into non-overlapping size groups for downstream analysis. Combining the results of weighted gene co-expression network and Trendy analyses, and differently expressed genes (DEGs) between size groups, we identified a decrease in oxidative phosphorylation and an increase in maternal -genes and transcription regulators across the bovine oocyte growth phase. In addition, around 5,000 genes did not change in expression, revealing a cohort of stable genes. An interesting switch in gene expression profile was noted in oocytes greater than 100 um in diameter, when the expression of genes related to cytoplasmic activities was replaced by genes related to nuclear activities (e.g., chromosome segregation). The highest number of DEGs were detected in the comparison of oocytes 100-109 versus 110-119 um in diameter, revealing a profound change in the molecular profile of oocytes at the end of their growth phase. The current study provides a unique dataset of the key genes and pathways characteristic of each stage of oocyte development, contributing an important resource for a greater understanding of bovine oogenesis.
Project description:To investigate the transcriptomic changes during the development and growth of ovarian granulosa cell tumors derived by oocyte-specific PIK3CA* transgene overexpression
Project description:Oocyte maturation is the foundation for developing healthy individuals of mammals. Upon germinal vesicle breakdown, oocyte meiosis resumes and the synthesis of new transcripts ceases. To quantitatively profile the transcriptomic dynamics after meiotic resumption throughout the oocyte maturation, we generated transcriptome sequencing data with individual mouse oocytes at three main developmental stages: germinal vesicle (GV), metaphase I (MI), and metaphase II (MII). When clustering the sequenced oocytes, results showed that isoform-level expression analysis outperformed gene-level analysis, indicating isoform expression provided extra information that was useful in distinguishing oocyte stages. Comparing transcriptomes of the oocytes at the GV stage and the MII stage, in addition to identification of differentially expressed genes (DEGs), we detected many differentially expressed transcripts (DETs), some of which came from genes that were not identified as DEGs. When breaking down the isoform-level changes into alternative RNA processing events, we found the main source of isoform composition changes was the alternative usage of polyadenylation sites. With detailed analysis focusing on the alternative usage of 3'-UTR isoforms, we identified, out of 3810 tested genes, 512 (13.7%) exhibiting significant switches of 3'-UTR isoforms during the process of moues oocyte maturation. Altogether, our data and analyses suggest the importance of examining isoform abundance changes during oocyte maturation, and further investigation of the pervasive 3'-UTR isoform switches in the transition may deepen our understanding on the molecular mechanisms underlying mammalian early development.