Project description:Total fertilization failure (TFF) is an important cause of infertility; however, the genetic basis of TFF caused by male factors remain to be clarified. In this study, whole-exome sequencing was firstly used to screen for genetic causes of TFF after intracytoplasmic sperm injection (ICSI), and homozygous variants in the novel gene IQ motif containing N (IQCN) were identified in two affected individuals with abnormal acrosome structure. Then, Iqcn knockout mice were generated by CRISPR-Cas9 technology and showed that the knockout male mice resembled TFF phenotype with oocyte activation failure. Additionally, we found that IQCN regulates the microtubule nucleation during manchette assembly via calmodulin and related calmodulin-binding proteins, which resulted in head deformity with aberrant oocyte activation factor PLCζ. Fortunately, ICSI with assisted oocyte activation can overcome IQCN-associate male infertility. Thus, our study firstly identifies the function of IQCN, highlights the relationship between the manchette assembly and fertilization, and provides a genetic marker and a therapeutic option for male-source TFF.
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:The oocyte epigenome plays critical roles in mammalian gametogenesis and embryogenesis. Yet, how it is established remains elusive. Here, we report that histone-lysine N-methyltransferase SETD2, an H3K36me3 methyltransferase, is a crucial regulator of the mouse oocyte epigenome. Deficiency in Setd2 leads to extensive alterations of the oocyte epigenome, including the loss of H3K36me3, failure in establishing the correct DNA methylome, invasion of H3K4me3 and H3K27me3 into former H3K36me3 territories and aberrant acquisition of H3K4me3 at imprinting control regions instead of DNA methylation. Importantly, maternal depletion of SETD2 results in oocyte maturation defects and subsequent one-cell arrest after fertilization. The preimplantation arrest is mainly due to a maternal cytosolic defect, since it can be largely rescued by normal oocyte cytosol. However, chromatin defects, including aberrant imprinting, persist in these embryos, leading to embryonic lethality after implantation. Thus, these data identify SETD2 as a crucial player in establishing the maternal epigenome that in turn controls embryonic development.
Project description:The oocyte epigenome plays critical roles in mammalian gametogenesis and embryogenesis. Yet, how it is established remains elusive. Here, we report that histone-lysine N-methyltransferase SETD2, an H3K36me3 methyltransferase, is a crucial regulator of the mouse oocyte epigenome. Deficiency in Setd2 leads to extensive alterations of the oocyte epigenome, including the loss of H3K36me3, failure in establishing the correct DNA methylome, invasion of H3K4me3 and H3K27me3 into former H3K36me3 territories and aberrant acquisition of H3K4me3 at imprinting control regions instead of DNA methylation. Importantly, maternal depletion of SETD2 results in oocyte maturation defects and subsequent one-cell arrest after fertilization. The preimplantation arrest is mainly due to a maternal cytosolic defect, since it can be largely rescued by normal oocyte cytosol. However, chromatin defects, including aberrant imprinting, persist in these embryos, leading to embryonic lethality after implantation. Thus, these data identify SETD2 as a crucial player in establishing the maternal epigenome that in turn controls embryonic development.
Project description:The oocyte epigenome plays critical roles in mammalian gametogenesis and embryogenesis. Yet, how it is established remains elusive. Here, we report that histone-lysine N-methyltransferase SETD2, an H3K36me3 methyltransferase, is a crucial regulator of the mouse oocyte epigenome. Deficiency in Setd2 leads to extensive alterations of the oocyte epigenome, including the loss of H3K36me3, failure in establishing the correct DNA methylome, invasion of H3K4me3 and H3K27me3 into former H3K36me3 territories and aberrant acquisition of H3K4me3 at imprinting control regions instead of DNA methylation. Importantly, maternal depletion of SETD2 results in oocyte maturation defects and subsequent one-cell arrest after fertilization. The preimplantation arrest is mainly due to a maternal cytosolic defect, since it can be largely rescued by normal oocyte cytosol. However, chromatin defects, including aberrant imprinting, persist in these embryos, leading to embryonic lethality after implantation. Thus, these data identify SETD2 as a crucial player in establishing the maternal epigenome that in turn controls embryonic development.
Project description:Splat-like 4 (Sall4) plays important roles in maintaining pluripotency of embryonic stem cells and in various developmental processes. Here, we find that the SALL4 null oocytes fail to undergo maturation to form fully-grown oocytes (FGOs) and subsequent meiosis resumption. We further discover that the loss of maternal SALL4 causes failure in establishment of DNA methylation. Moreover, we demonstrate that SALL4 modulates H3K4me3 and H3K27me3 modifications by regulating the expression of Kdm5b, Kdm6a and Kdm6b. Taken together, SALL4 plays pivotal roles in oocyte epigenetic maturation.
Project description:Splat-like 4 (Sall4) plays important roles in maintaining pluripotency of embryonic stem cells and in various developmental processes. Here, we find that the SALL4 null oocytes fail to undergo maturation to form fully-grown oocytes (FGOs) and subsequent meiosis resumption. We further discover that the loss of maternal SALL4 causes failure in establishment of DNA methylation. Moreover, we demonstrate that SALL4 modulates H3K4me3 and H3K27me3 modifications by regulating the expression of Kdm5b, Kdm6a and Kdm6b. Taken together, SALL4 plays pivotal roles in oocyte epigenetic maturation.
Project description:Oocyte maturation is accompanied by a transition from mRNA stability to instability. We investigated the role of DCP1A and DCP2, proteins responsible for mRNA decapping, in mRNA destabilization during mouse oocyte maturation. siRNA-mediated knockdown of both Dcp1a and Dcp2 transcripts prior to initiation of maturation inhibited the maturation-associated increase of DCP1A and DCP2, stabilized a set of maternal mRNAs that are normally degraded during maturation, and inhibited development beyond the 2-cell stage, likely a consequence of failure to activate fully the zygotic genome. Total RNA from 30 MII eggs was used in each sample. Three independent biological replicates were analyzed for each condition.
Project description:In vitro maturation (IVM) of the oocytes is a routine method in bovine embryo production. The competence of bovine oocytes to develop into embryo after IVM and in vitro fertilization (IVF) is lower as compared to in vivo preovulatory oocytes. Cumulus cells (CC) that enclose an oocyte are involved in the acquisition of oocyte quality during maturation. Using transcriptomic approach we compared cumulus cells gene expression during IVM with that in vivo preovulatory period.
Project description:Oocyte maturation defects are one contributing factor in unexplained female infertility. Failure of some oocytes to undergo germinal vesicle breakdown or progress to second meiotic metaphase in response to an ovulatory stimulus can limit the number of high quality oocytes available for assisted reproduction. Understanding the molecular mechanisms that underlie oocyte maturation failure may lead to novel methods for increasing the number of high quality oocytes available for assisted reproduction, as well as providing new insight into the basic biology of oocyte maturation. Using RNA sequencing, we compared the transcriptome of rhesus monkey oocytes that failed to mature (FTM) in response to an ovulatory stimulus in vivo to normal germinal vesicle and metaphase II stage oocytes.