Project description:PRDM proteins are metazoan specific transcriptional regulators that play diverse roles in mammalian development and disease. Several members such as PRDM1, PRDM14 and PRDM9, have been implicated in germ cell formation and homeostasis and are essential to fertility-related processes. Others, such as PRDM14, PRDM15 and PRDM10 play a role in early embryogenesis and embryonic stem cell maintenance. Here, we reveal an additional maternal requirement for PRDM10 . Absence of maternal Prdm10 results in catastrophic failure of oocyte-to-embryo transition and complete arrest at the 2-cell stage. We describe multiple defects in oocytes, zygotes and 2-cell stage embryos relating to the failure to accumulate PRDM10 target gene transcripts in the egg. Transcriptomic analysis and integration of genome-wide chromatin-binding data reveals novel, essential PRDM10 targets, including the cytoskeletal protein SEPTIN11. We demonstrate that the failure to express maternal Septin11, in the absence of maternal PRDM10, disrupts Septin-complex assembly at the polar body extrusion site in MII oocytes. Our study sheds light into the essentiality of maternal PRDM10, the requirement of the maternal Septin-complex and the likely evolutionary conservation of this regulatory axis in human female germ cells.
Project description:Sirtuin-1 (Sirt1), a NAD+-dependent histone deacetylase, exhibits several properties of a versatile driver of maternal-zygotic transition, due to its epigenetic and non-epigenetic substrates. The study was aimed at the dynamics of Sirt1 in early embryos and the contribution to maternal-zygotic transition. A conditional Sirt1-deficient knock-out mouse model was used. Females were hormonally stimulated and used as oocyte donors. oocytes were parthenogenetically activated and Sirt1-/- two-cell embryos were used for transcriptomic analysis.
Project description:We analyzed the functions of ERK in maternal mRNA degradation in mouse oocytes. By comparing the degradation of transcripts in WT oocytes and KO oocytes, we are able to know the defects in maternal mRNA clearance in ERK-deleted oocytes, and identified the ERK target genes in oocyte maturation.
Project description:The oocytes of many species, both invertebrate and vertebrate, contain a large collection of localized determinants in the form of proteins and translationally inactive maternal mRNAs. However, it is unknown whether mouse oocytes contain localized MmRNA determinants and what mechanisms might be responsible for their control. We collected intact MII oocytes, enucleated MII oocyte cytoplasts (with the spindle removed), and spindle-chromosome complexes which had been microsurgically removed. RNA was extracted, amplified, labeled, and applied to microarrays to determine if any MmRNA determinants were localized to the SCC. We used microarrays to determine whether maternal mRNAs in mouse oocytes are enriched in the meiotic spindle
Project description:The long-standing view of 'immortal germ line versus mortal soma' poses a fundamental question in biology concerning how oocytes age in molecular terms. A mainstream hypothesis is that maternal aging of oocytes has its roots in gene transcription. Investigating the proteins resulting from mRNA translation would reveal how far the levels of functionally available proteins correlate with mRNAs, and would offer novel insight into the changes oocytes undergo during maternal aging. Gene ontology semantic analysis reveals the high similarity of the detected proteome (2,324 proteins) to the transcriptome (22,334 mRNAs), though not all proteins have a cognate mRNA. Concerning their dynamics, 4-fold changes of abundance are more frequent in the proteome (3%) than the transcriptome (0.05%), with correlation. Whereas proteins associated with the nucleus (e.g. structural maintenance of chromosomes, spindle-assembly checkpoints) are largely represented among those that change in oocytes during maternal aging; proteins associated with oxidative stress/damage (e.g. superoxide dismutase) are infrequent. These quantitative alterations are either impoverishing or enriching. Using gene ontology analysis, these alterations do not relate in any simple way to the classic signature of aging known from somatic tissues. We conclude that proteome analysis of mouse oocytes may not be surrogated with transcriptome analysis, given the lack of correlation. Furthermore, we conclude that the classic features of aging may not be transposed from somatic tissues to oocytes in a one-to-one fashion. Overall, there is more to the maternal aging of oocytes than mere cellular deterioration exemplified by the notorious increase of meiotic aneuploidy. Three pools of 20 zona-enclosed B6C3F1 oocytes from each age group were subjected for experiment.
Project description:STUDY QUESTION: Does maternal age affect the maturated oocyte quality and the fol-lowing development after fertilization in human? SUMMARY ANSWER: Maternal age affects the quality of maturated oocytes by altering the stored mRNA levels in human, such as TOP2B. WHAT IS KNOWN ALREADY: Intracellular mRNAs in maturated oocytes are tran-scripted from the maternal genome during oogenesis and important for the zygotic genome activation (ZGA) after fertilization. Microarray data showed that maternal age affected polyadenylated transcript abundance in human oocytes. These genes are involved in in signaling pathway related to cell cycle regulation, chromosome alignment. However, which genes are the key genes affected by maternal age and important for the development after fertilization had not been reported. Therefore, single-cell RNA sequencing (scRNA-Seq) technology is employed in this study to screen the key genes affected by maternal age in human maturated oocytes. STUDY DESIGN, SIZE, DURATION: We isolated mRNA from maturated (MII) oo-cytes donated by IVF or ICSI patients (three oocytes from young (≤ 30 years) and three oocytes from advanced maternal age (≥ 40 years) patients) undergoing controlled ovarian stimulation. Thus, a total of six maturated oocytes were individually processed for scRNA-seq analysis. The key genes screened from scRNA-seq analysis are confirmed using mouse model. PARTICIPANTS/MATERIALS, SETTING, METHODS: Patients undergoing infertility treatment at the Yuhuangding Hospital of Yantai underwent ovarian stimulation with FSH and received hCG for final follicular maturation prior to ul-trasound guided oocyte retrieval. We isolated RNA, generated single cell RNA-seq librar-ies (Smart-Seq2) and sequenced by Illumina Hiseq X-ten platform with 150 bp paired-end. Bioinformatics analysis of the sequencing data was done to find the biological processes and key genes that led to the decline in the quality of oocytes with advanced maternal age. To validate the findings, we used mouse model and validated candidate genes by RT-PCR and knockdown experiments. MAIN RESULTS AND THE ROLE OF CHANCE: We identified 1439 genes differentially expressed between older and younger women's maturated oocytes (|foldchange|>2, P < 0.05). These genes are significantly enriched with annotations related to transporter activity, cytoskeleton, oxidative stress, catalytic activity, immune function, cellular senescence and biosynthesis. The key candidate gene TOP2B was found by protein interaction network analysis, and knockdown verification on young mouse maturated oocytes showed that TOP2B was a key gene affecting the oocyte quality and disturbing early embryo development. LARGE SCALE DATA Raw data from this study can be accessed through GSE. LIMITATIONS, REASONS FOR CAUTION: The human maturated oocytes used in this study were from patients with different causes of infertility and may affect oocyte gene expression. In addition, the study was based on a lim-ited number of patients, and there are possible natural biological variance existed in human samples. WIDER IMPLICATIONS OF THE FINDINGS: For the first time, we used scRNA-seq to detect global gene transcriptome of maturated oocytes in young and older women. These results are useful to indicate the molecular mechanisms of female ovary aging and establishing a criterion to evaluate the quality of oocytes in women with advanced maternal age. STUDY FUNDING/COMPETING INTERESTS: This research was supported by the National Key Research and Development Program of China (2018YFC1004304, 2016YFA0100203), Medical and Health Science Technology Development Plan Project of Shandong Province (Grant#. 2017WS566). There are no competing interests.