Project description:In fully grown oocytes, the genome is considered to be globally transcriptionally silenced. However, this conclusion is primarily derived from the results obtained through immunofluorescence staining or inferred from the highly condensed state of chromosomes, lacking more direct evidence. Here, by using a kethoxal-assisted single-stranded DNA sequencing (KAS-seq) approach, we investigated the landscape of single-strand DNA (ssDNA) throughout the genome and provided a readout of the activity and dynamics of transcription during oocyte meiotic maturation. In non-surrounded nucleolus (NSN) oocytes, we observed a robust KAS-seq signal, indicating the high transcriptional activity. In surrounded nucleolus (SN) oocytes, the presence of ssDNA still persists although the KAS-seq signal was relatively weak, suggesting the presence of transcription. Accompanying with the meiotic resumption, the transcriptional activity gradually decreased, and global repression was detected in matured oocytes. Moreover, we preformed the integrative genomics analysis to dissect the transcriptional dynamics during mouse oocyte maturation. In sum, the present study delineates the detailed transcriptional activity during mammalian oocyte maturation.
Project description:Kethoxal-assisted ssDNA sequencing (KAS-seq) is gaining popularity as a robust and effective approach to study the dynamics of transcriptionally engaged RNA polymerases through profiling of genome-wide single-stranded DNA (ssDNA). Its latest variant, spKAS-seq, a strand-specific version of KAS-seq, has been developed to map genome-wide R-loop structures by detecting imbalances of ssDNA on two strands. However, user-friendly, open-source, and specific bioinformatic analyzer for KAS-seq data are still lacking. Here we present KAS-Analyzer as a flexible and integrated toolkit to facilitate the analysis and interpretation of KAS-seq data. KAS-Analyzer can perform standard analyses such as quality control, read alignment, and differential RNA polymerase activity analysis. In addition, KAS-Analyzer introduces many novel features, including, but not limited to: calculation of transcriptional indexes, identification of single-stranded transcribing enhancers, and high-resolution mapping of R-loops. We use benchmark datasets to demonstrate that KAS-Analyzer provides a powerful framework to study transient transcriptional regulatory programs. KAS-Analyzer is available at https://github.com/Ruitulyu/KAS-Analyzer.
Project description:The sequences deposited within this study are for the analysis of the changing transcriptome during zebrafish oocyte maturation. This dataset will be used to study the differential expression of mRNAs during oocyte maturation and also mechanisms of RNA stability and degradation, transcription and polyadenylation. Sequences will be generated using polyA selection and then, after reverse transcription, generated into illumina libraries. This data is part of a pre-publication release. For information on the proper use of pre-publication data shared by the Wellcome Trust Sanger Institute (including details of any publication moratoria), please see http://www.sanger.ac.uk/datasharing/
Project description:SIRT6, the sixth member of sirtuin family proteins, has been identified as a crucial regulator in multiple molecular pathways related to aging, including genome stability, DNA damage repair, telomere maintenance and inflammation. However, the exact roles of SIRT6 during mammalian oocyte meiosis have not yet fully clarified. Here, we investigated the critical events during porcine oocyte meiotic maturation with the treatment of SIRT6 specific inhibitor SIRT6-IN-1. We found that SIRT6 inhibition resulted in oocyte meiotic failure by displaying the poor expansion of cumulus cells and reduced rate of polar body extrusion. Meanwhile, the compromised spindle assembly, chromosome alignment and actin dynamics were also observed in SIRT6-inhibited oocytes. Moreover, inhibition of SIRT6 led to the defective cytoplasmic maturation by showing the abnormal distribution of cortical granules and their component ovastacin. Notably, we identified that expression of genes related to oocyte meiosis, oxidative phosphorylation and cellular senescence was remarkably altered in SIRT6-inhibited oocytes by transcriptome analysis, and validated that the meiotic defects caused by SIRT6 inhibition resulted from the excessive ROS-induced early apoptosis in oocytes. Taken together, our findings demonstrate that SIRT6 promotes the porcine oocyte meiotic maturation via maintaining the organelle dynamics.
Project description:The genetic causes of oocyte meiotic deficiency (OMD), a form of primary infertility characterised by the production of immature oocytes, remain largely unexplored. Using whole exome sequencing, we found that 26% of a cohort of 23 subjects with OMD harboured the same homozygous nonsense pathogenic mutation in PATL2, a gene encoding a putative RNA-binding protein. Using Patl2 knockout mice, we confirmed that PATL2 deficiency disturbs oocyte maturation, since oocytes and zygotes exhibit morphological and developmental defects respectively. PATL2's amphibian orthologue is involved in the regulation of oocyte mRNA as a partner of CPEB. However, Patl2's expression profile throughout oocyte development in mice, alongside colocalisation experiments with Cpeb1, Msy2 and Ddx6 (three oocyte RNA-regulators) suggest an original role for Patl2 in Mammals. Accordingly, transcriptomic analysis of oocytes from WT and Patl2-/- animals demonstrated that in the absence of Patl2, expression levels of a select number of highly relevant genes involved in oocyte maturation and early embryonic development are deregulated. In conclusion, PATL2 is a novel actor of mammalian oocyte maturation whose invalidation causes OMD in humans.
Project description:Cis-regulatory elements (CREs) are pivotal in orchestrating gene expression throughout diverse biological systems. Accurate identification and in-depth characterization of functional CREs are crucial for decoding gene regulation network and dynamics during cellular processes. In this study, we developed a new KAS-seq (Opti-KAS-seq) procedure, with enhanced efficiency of capturing single-stranded DNA (ssDNA), broader genomic coverage, and adaptability to various sample types. By integrating the highly sensitive Opti-KAS-seq with ATAC-seq, we further introduce KAS-ATAC-seq, a new method that provides quantitative insights into transcriptional activity of CREs. A main advantage of KAS-ATAC-seq lies in its precise measurement of ssDNA levels within both proximal and distal ATAC-seq peaks. This feature is particularly adept at identifying ssDNA promoter and Single-Stranded Transcribing Enhancers (SSTEs). SSTEs are highly enriched with nascent RNA transcripts and specific transcription factors (TFs) binding sites that determine cellular identity. Moreover, KAS-ATAC-seq provides a detailed characterization and functional implications of various SSTE subtypes; KAS-ATAC-seq signals exhibit more robust correlation with enhancer activities when compared with ATAC-seq data and active histone mark profiles. Our analysis of promoters and SSTEs during mouse neural differentiation demonstrates that KAS-ATAC-seq can effectively identify immediate-early activated CREs in response to RA treatment. We further discovered that ETS TFs and YY1 are critical in initiating early neural differentiation from mESCs to NPCs. Our findings indicate that KAS-ATAC-seq provides more precise annotation of functional CREs in transcription. Future applications of KAS-ATAC-seq would help elucidate the intricate dynamics of gene regulation in diverse biological processes and biomedical applications.
Project description:Cis-regulatory elements (CREs) are pivotal in orchestrating gene expression throughout diverse biological systems. Accurate identification and in-depth characterization of functional CREs are crucial for decoding gene regulation network and dynamics during cellular processes. In this study, we developed a new KAS-seq (Opti-KAS-seq) procedure, with enhanced efficiency of capturing single-stranded DNA (ssDNA), broader genomic coverage, and adaptability to various sample types. By integrating the highly sensitive Opti-KAS-seq with ATAC-seq, we further introduce KAS-ATAC-seq, a new method that provides quantitative insights into transcriptional activity of CREs. A main advantage of KAS-ATAC-seq lies in its precise measurement of ssDNA levels within both proximal and distal ATAC-seq peaks. This feature is particularly adept at identifying ssDNA promoter and Single-Stranded Transcribing Enhancers (SSTEs). SSTEs are highly enriched with nascent RNA transcripts and specific transcription factors (TFs) binding sites that determine cellular identity. Moreover, KAS-ATAC-seq provides a detailed characterization and functional implications of various SSTE subtypes; KAS-ATAC-seq signals exhibit more robust correlation with enhancer activities when compared with ATAC-seq data and active histone mark profiles. Our analysis of promoters and SSTEs during mouse neural differentiation demonstrates that KAS-ATAC-seq can effectively identify immediate-early activated CREs in response to RA treatment. We further discovered that ETS TFs and YY1 are critical in initiating early neural differentiation from mESCs to NPCs. Our findings indicate that KAS-ATAC-seq provides more precise annotation of functional CREs in transcription. Future applications of KAS-ATAC-seq would help elucidate the intricate dynamics of gene regulation in diverse biological processes and biomedical applications.