Project description:Fully grown oocytes remain transcriptionally quiescent, yet many maternal mRNAs are synthesized and retained in growing oocytes. We now know that maternal mRNAs are stored in a structure called the mitochondria associated ribonucleoprotein domain (MARDO). But the components and functions of MARDO remain elusive. Here, we found that LSM14B knockout prevents the proper storage and timely clearance of mRNAs (including Cyclin B1, Btg4, and other mRNAs that are translationally activated during meiotic maturation), specifically by disrupting MARDO assembly during oocyte growth and meiotic maturation. With decreased levels of storage and clearance, the LSM14B knockout oocytes failed to enter meiosis II, ultimately resulting in female infertility. Our results demonstrate the function of LSM14B in MARDO assembly, couple the MARDO with mRNA clearance and oocyte meiotic maturation
Project description:Oocyte maturation refers to oocytes at the germinal vesicle stage progressing into metaphase II (MII) stage of development. Even though numerous studies have shown key genes and potential important signalling cascades, which drive the GV to MII transition, a system-wide analysis of underlying differences at gene level and especially at transcript level between the two developmental stages of the oocyte is still lacking. For this, we profiled and analysed RNA from pig oocytes across meiotic maturation (GV, MII and damaged, n=15). We detected 22,516 genes for each sample across meiotic maturation. Principal Component analysis of the data clustered the samples in three stages of development (GV, MII and damaged). Differential expression of genes between the three stages will then be used to delineate the pathways which are up-/down-regulated during these developmental stages. Besides, differential transcript usage will be used to identify the difference of oocytes at distinct developmental stages at isoform level, which might be ignored by traditional differential gene expression analysis.
Project description:Fully grown oocytes remain transcriptionally quiescent, yet many maternal mRNAs are synthesized and retained in growing oocytes. We now know that maternal mRNAs are stored in a structure called the mitochondria associated ribonucleoprotein domain (MARDO). But the components and functions of MARDO remain elusive. Here, we found that LSM14B knockout prevents the proper storage and timely clearance of mRNAs (including Cyclin B1, Btg4, and other mRNAs that are translationally activated during meiotic maturation), specifically by disrupting MARDO assembly during oocyte growth and meiotic maturation. With decreased levels of storage and clearance, the LSM14B knockout oocytes failed to enter meiosis II, ultimately resulting in female infertility. Our results demonstrate the function of LSM14B in MARDO assembly, couple the MARDO with mRNA clearance and oocyte meiotic maturation.
Project description:Mammalian oocyte maturation is driven by strictly translational regulation of maternal mRNAs stored in the cytoplasm. However, the function and mechanism of post-transcriptional chemical modifications especially the newly identified N4-acetylcytidine (ac4C) catalyzed by N-acetyltransferase 10 (NAT10) in this process are previously unknown. In this study, we developed a low-input ac4C sequencing technology - ac4C LACE-seq and mapped 8241 ac4C peaks at the whole transcriptome level using 50 mouse oocytes at the germinal vesicle (GV) stage. We profiled the mRNA landscapes of NAT10-interactions and ac4C modifications. The NAT10-interacted and ac4C modified transcripts displayed association with high translation efficiency in oocytes. Oocyte-specific Nat10 knockout wiped out ac4C signals in oocytes and caused severe defects in meiotic maturation and female infertility. ac4C LACE-seq results indicated that Nat10 deletion led to a failure of ac4C deposition on mRNAs encoding key maternal factors such as MAY2, ZAR1, BTG4 and cyclin B1 that regulate transcriptome stability and maternal-to-zygotic transition. Nat10-deleted oocytes had decreased mRNA translation efficiencies during meiotic maturation, partially due to the direct inhibition ac4C sites on specific transcripts. In sum, we developed low-input, high-sensitivity mRNA ac4C profiling approach and highlighted the important physiological function of ac4C in precise regulation of the oocyte meiotic maturation by enhancing translation efficiency.
Project description:Mammalian oocyte maturation is driven by strictly translational regulation of maternal mRNAs stored in the cytoplasm. However, the function and mechanism of post-transcriptional chemical modifications especially the newly identified N4-acetylcytidine (ac4C) catalyzed by N-acetyltransferase 10 (NAT10) in this process are previously unknown. In this study, we developed a low-input ac4C sequencing technology—ac4C LACE-seq and mapped 8241 ac4C peaks at the whole transcriptome level using 50 mouse oocytes at the germinal vesicle (GV) stage. We profiled the mRNA landscapes of NAT10-interactions and ac4C modifications. The NAT10-interacted and ac4C modified transcripts displayed association with high translation efficiency in oocytes. Oocyte-specific Nat10 knockout wiped out ac4C signals in oocytes and caused severe defects in meiotic maturation and female infertility. ac4C LACE-seq results indicated that Nat10 deletion led to a failure of ac4C deposition on mRNAs encoding key maternal factors such as MAY2, ZAR1, BTG4 and cyclin B1 that regulate transcriptome stability and maternal-to-zygotic transition. Nat10-deleted oocytes had decreased mRNA translation efficiencies during meiotic maturation, partially due to the direct inhibition ac4C sites on specific transcripts. In sum, we developed low-input, high-sensitivity mRNA ac4C profiling approach and highlighted the important physiological function of ac4C in precise regulation of the oocyte meiotic maturation by enhancing translation efficiency.
Project description:Purpose: The goals of this study are to study the function of Cnot6l during oocyte maturation and the differences between loss of Cnot6l and Btg4 during oocyte maturation. Methods:Comparing the degration of transcripts at different stage in WT, Btg4-/- and Cnot6l-/- oocytes by RNA sequencing. Results: Using an optimized data analysis workflow, we mapped about 15 million sequence reads per sample to the mouse genome (build mm9) and identified 23236 transcripts with TopHat workflow. Conclusions: CNOT6L stimulated degradation of maternal transcriptsto oocyte meiotic maturation.
Project description:N4-acetylcytidine (ac4C), a newly identified epigenetic modification within mRNAs, has been characterized as a crucial regulator of mRNA stability and translation efficiency. And NAT10 is the only known RNA acetyltransferase. In our study, we documented the down-regulated expression of both ac4C and NAT10 during meiotic maturation of mouse oocytes. NAT10 knockdown resulted in ac4C reduction and impaired mouse oocyte maturation in vitro. These results indicated that NAT10-mediated ac4C modification plays a critical regulatory role in oocyte meiotic maturation. We further performed high-throughput sequencing with NAT10-overexpressed HEK293T cells and NAT10-binding transcripts to investigate the genes modulated by NAT10-mediated ac4C modification.
Project description:Well balanced and timed energy metabolism is essential for making a high quality egg. However, the metabolic framework that supports oocyte development remains poorly understood. Here we obtained the temporal metabolome profiles of mouse oocytes during in vivo maturation by isolating large number of cells at key stages. In parallel, quantitative proteomic analyses were conducted to bolster the metabolomic data, synergistically depicting the global metabolic patterns in oocytes. In particular, we discovered novel metabolic features during oocyte maturation, such as the fall in polyunsaturated fatty acids (PUFAs) level and the active serine-glycine-one-carbon (SGOC) pathway. Using functional approaches, we further identified two key targets (NKAP and BTG4) through which arachidonic acid (ARA) inhibits meiotic maturation, and demonstrated the control of epigenetic marks in maturing oocytes by SGOC network. Our data serves as a broad resource on the dynamics occurring in metabolome and proteome during oocyte maturation, and provides opportunities for predicting and improving oocyte quality.