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Comment |
Expression of maternally derived KHDC3, NLRP5, OOEP and TLE6 is associated with oocyte developmental competence in the ovine species. Bebbere D et al. (2015) The sub-cortical maternal complex (SCMC), located in the subcortex of mouse oocytes and preimplantation embryos, is composed of at least four proteins encoded by maternal effect genes: OOEP, NLRP5/MATER, TLE6 and KHDC3/FILIA. The SCMC assembles during oocyte growth and was seen to be essential for murine zygote progression beyond the first embryonic cell divisions; although roles in chromatin reprogramming and embryonic genome activation were hypothesized, the full range of functions of the complex in preimplantation development remains largely unknown. Here we report the expression of the SCMC genes in ovine oocytes and pre-implantation embryos, describing for the first time its expression in a large mammalian species. We report sheep-specific patterns of expression and a relationship with the oocyte developmental potential in terms of delayed degradation of maternal SCMC transcripts in pre-implantation embryos derived from developmentally incompetent oocytes. In addition, by determining OOEP full length cDNA by Rapid Amplification of cDNA Ends (RACE) we identified two different transcript variants (OOEP1 and OOEP2), both expressed in oocytes and early embryos, but with different somatic tissue distributions. In silico translation showed that 140 aminoacid peptide OOEP1 shares an identity with orthologous proteins ranging from 95% with the bovine to 45% with mouse. Conversely, OOEP2 contains a premature termination codon, thus representing an alternative noncoding transcript and supporting the existence of aberrant splicing during ovine oogenesis. These findings confirm the existence of the SCMC in sheep and its key role for the oocyte developmental potential, deepening our understanding on the molecular differences underlying cytoplasmic vs nuclear maturation of the oocytes. Describing differences and overlaps in transcriptome composition between model organisms advance our comprehension of the diversity/uniformity between mammalian species during early embryonic development and provide information on genes that play important regulatory roles in fertility in nonmurine models, including the human.Maternal-effect gene Ces5/Ooep/Moep19/Floped is essential for oocyte cytoplasmic lattice formation and embryonic development at the maternal-zygotic stage transition. Tashiro F et al. (2010) In a search for genes specifically expressed in mouse embryonic stem cells, we identified one we called Ces5. We found that it corresponded to the Ooep gene, which was recently reported to be expressed specifically in oocytes. Mouse Ces5/Ooep, also called Moep19 or Floped, encoded a 164-amino acid protein, which was detected in the cytoplasm of developing and mature oocytes and in embryos throughout the preimplantation period. To examine its function, we carried out targeted disruption of this gene. The Ces5/Ooep-null mice were grossly normal, but the females were infertile. Although the ovaries and ovulation appeared normal, the embryos from Ces5/Ooep-null females mated with wild-type males showed developmental arrest at the two- or four-cell stage. In addition, their first cleavage was considerably delayed and often asymmetrical. Thus, Ces5/Ooep is a maternal-effect gene. By electron microscopy, we found that the eggs from Ces5/Ooep-null females lacked oocyte cytoplasmic lattices (CPLs), which have long been predicted to function as a storage form for components that are maternally contributed to the early embryo. Further analysis showed that CES5/OOEP was directly associated with the CPLs. These results indicate that CES5/OOEP is an essential component of the CPLs and is required for embryonic development at the maternal-zygotic stage transition.Atypical structure and phylogenomic evolution of the new eutherian oocyte- and embryo-expressed KHDC1/DPPA5/ECAT1/OOEP gene family. Pierre A et al. (2007) Several recent studies have shown that genes specifically expressed by the oocyte are subject to rapid evolution, in particular via gene duplication mechanisms. In the present work, we have focused our attention on a family of genes, specific to eutherian mammals, that are located in unstable genomic regions. We have identified two genes specifically expressed in the mouse oocyte: Khdc1a (KH homology domain containing 1a, also named Ndg1 for Nur 77 downstream gene 1, a target gene of the Nur77 orphan receptor), and another gene structurally related to Khdc1a that we have renamed Khdc1b. In this paper, we show that Khdc1a and Khdc1b belong to a family of several members including the so-called developmental pluripotency A5 (Dppa5) genes, the cat/dog oocyte expressed protein (cat OOEP and dog OOEP) genes, and the ES cell-associated transcript 1 (Ecat1) genes. These genes encode structurally related proteins that are characterized by an atypical RNA-binding KH domain and are specifically expressed in oocytes and/or embryonic stem cells. They are absent in fish, bird, and marsupial genomes and thus seem to have first appeared in eutherian mammals, in which they have evolved rapidly. They are located in a single syntenic region in all mammalian genomes studied, except in rodents, in which a synteny rupture due to a paracentric inversion has separated this gene family into two genomic regions and seems to be associated with increased instability in these regions. Overall, we have identified and characterized a novel family of oocyte and/or embryonic stem cell-specific genes encoding proteins that share an atypical KH RNA-binding domain and that have evolved rapidly since their emergence in eutherian mammalian genomes.
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Comment |
Atypical structure and phylogenomic evolution of the new eutherian oocyte- and embryo-expressed KHDC1/DPPA5/ECAT1/OOEP gene family. Pierre A et al. Several recent studies have shown that genes specifically expressed by the oocyte are subject to rapid evolution, in particular via gene duplication mechanisms. In the present work, we have focused our attention on a family of genes, specific to eutherian mammals, that are located in unstable genomic regions. We have identified two genes specifically expressed in the mouse oocyte: Khdc1a (KH homology domain containing 1a, also named Ndg1 for Nur 77 downstream gene 1, a target gene of the Nur77 orphan receptor), and another gene structurally related to Khdc1a that we have renamed Khdc1b. In this paper, we show that Khdc1a and Khdc1b belong to a family of several members including the so-called developmental pluripotency A5 (Dppa5) genes, the cat/dog oocyte expressed protein (cat OOEP and dog OOEP) genes, and the ES cell-associated transcript 1 (Ecat1) genes. These genes encode structurally related proteins that are characterized by an atypical RNA-binding KH domain and are specifically expressed in oocytes and/or embryonic stem cells. They are absent in fish, bird, and marsupial genomes and thus seem to have first appeared in eutherian mammals, in which they have evolved rapidly. They are located in a single syntenic region in all mammalian genomes studied, except in rodents, in which a synteny rupture due to a paracentric inversion has separated this gene family into two genomic regions and seems to be associated with increased instability in these regions. Overall, we have identified and characterized a novel family of oocyte and/or embryonic stem cell-specific genes encoding proteins that share an atypical KH RNA-binding domain and that have evolved rapidly since their emergence in eutherian mammalian genomes.
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Mutations |
1 mutations
Species: mouse
Mutation name: None
type: null mutation
fertility: infertile - ovarian defect
Comment: Maternal-effect gene Ces5/Ooep/Moep19/Floped is essential for oocyte cytoplasmic lattice formation and embryonic development at the maternal-zygotic stage transition. Tashiro F et al. In a search for genes specifically expressed in mouse embryonic stem cells, we identified one we called Ces5. We found that it corresponded to the Ooep gene, which was recently reported to be expressed specifically in oocytes. Mouse Ces5/Ooep, also called Moep19 or Floped, encoded a 164-amino acid protein, which was detected in the cytoplasm of developing and mature oocytes and in embryos throughout the preimplantation period. To examine its function, we carried out targeted disruption of this gene. The Ces5/Ooep-null mice were grossly normal, but the females were infertile. Although the ovaries and ovulation appeared normal, the embryos from Ces5/Ooep-null females mated with wild-type males showed developmental arrest at the two- or four-cell stage. In addition, their first cleavage was considerably delayed and often asymmetrical. Thus, Ces5/Ooep is a maternal effect gene. By electron microscopy, we found that the eggs from Ces5/Ooep-null females lacked oocyte cytoplasmic lattices (CPLs), which have long been predicted to function as a storage form for components that are maternally contributed to the early embryo. Further analysis showed that CES5/OOEP was directly associated with the CPLs. These results indicate that CES5/OOEP is an essential component of the CPLs and is required for embryonic development at the maternal-zygotic stage transition.
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