Hypomethylation of paternal DNA in the late mouse zygote is not essential for development

Polanski, Zbigniew; Motosugi, Nami; Tsurumi, Chizuko; Hiiragi, Takashi; Hoffmann, Steffen

doi:10.1387/ijdb.072347zp

Cited by 37 publications

(27 citation statements)

References 17 publications

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“…In this regard it has been shown that when round spermatids are injected into the mouse oocytes, the level of demethylation was lower in male chromatin of round spermatid when compared with normal sperm. Consistent with the above the DNA methylation level was higher in round spermatid than the normal sperm [Polanski et al 2007]. After fertilization, as the replacement of the protamines occurs with histones, bare DNA is probably exposed to demethylation elements.…”

Section: Discussionsupporting

confidence: 64%

Pronuclear epigenetic modification of protamine deficient human sperm following injection into mouse oocytes

Rajabi

Mohseni-Kouchesfehani

Mohammadi‐Sangcheshmeh

et al. 2016

Systems Biology in Reproductive Medicine

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Epigenetic abnormalities and abnormal chromatin structure in sperm may lead to male infertility. Protamine deficiency is among the disorders of chromatin structure in sperm. The study of epigenetic changes in male pronuclei is necessary since abnormal sperm is sometimes used to create embryos using assisted reproductive techniques. The present study was carried out to compare epigenetic global marks in male pronuclei derived from normal and protamine deficient sperm cells. To do so, interspecies fertilization was used to obtain the male pronucleus. Normal and protamine deficient sperm cells, which were identified by chromomycin A3 staining, were injected into mouse oocytes. Oocytes were cultured until pronuclear formation and were then labeled with different antibodies (anti 5-methylcytosine, anti 5-hydroxymethylcytosine, and anti acetyl H4K12). Based on the fluorescence intensity, the level of each of these epigenetic factors was determined and they revealed a significant relationship between the level of sperm protamine deficiency and sperm epigenetic factors. Protamine deficiency was found to be associated with an increased methylation (p=0) and decreased hydroxymethylation rate (p=0.015) of the male pronucleus chromatin. However, no association was found between protamine deficiency and the level of H4K12 acetylation (p=0.548). Also, the efficiency of fertilization in protamine deficient sperm cells was less than normal. These results suggest that protamine deficient sperm cells lead to the formation of epigenetically altered pronuclei.

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Section: Discussionsupporting

confidence: 64%

Pronuclear epigenetic modification of protamine deficient human sperm following injection into mouse oocytes

Rajabi

Mohseni-Kouchesfehani

Mohammadi‐Sangcheshmeh

et al. 2016

Systems Biology in Reproductive Medicine

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“…Otherwise, the presence of some zygotes showing RM<0.4 indicates that the bovine paternal genome can undergo severe genome-wide demethylation under certain circumstances. On the other hand, this is the first study to report pronuclear-stage zygotes showing RM≥1.0; such RM values have been reported in mouse zygotes produced by ICSI and round spermatid injection [48]. The appearance of such zygotes may be due to failure of the oocytes to actively demethylate the paternal genome, as paternal genome has been referred to be relatively hypermethylated than maternal genome in the mouse [49,50].…”

Section: Discussionmentioning

confidence: 71%

Demethylation Dynamics of the Paternal Genome in Pronuclear-Stage Bovine Zygotes Produced by In Vitro Fertilization and Ooplasmic Injection of Freeze-Thawed or Freeze-Dried Spermatozoa

Abdalla

Hirabayashi

Hochi

2009

Journal of Reproduction and Development

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Abstract. This study was designed to investigate the dynamics of the paternal genome demethylation in pronuclearstage bovine zygotes produced either by in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) using freeze-thawed (FT) as well as freeze-dried (FD) bull sperm stored at +4 or -196 C for one year. Zygotes were fixed and immunostained using anti-5-methyl-cytosin at 8, 10, 14 and 18 h post IVF (hpi) and at 6 and 12 h post ICSI (hpic). In conventional IVF-derived zygotes, the overall average of the relative methylation (RM; male/female) decreased from 0.92 at 8 hpi to 0.69 at 10 hpi (P<0.05) without any additional decrease at 14 and 18 hpi (0.67 and 0.64, respectively; P>0.05). This was accompanied by higher proportions of zygotes showing RM<0.6 (45.5, 37.5 and 38.2% at 10, 14 and 18 hpi, respectively; P<0.05) compared with 3.7% at 8 hpi. The overall averages of the RM in the FT-ICSI derived zygotes (0.79 and 0.66 at 6 and 12 hpic, respectively) were similar to those in the corresponding IVF-derived zygotes (8 and 14 hpi), but a higher proportion of the 6 hpic zygotes (37.8%; P<0.05) showed an RM<0.6 compared with the 8 hpi zygotes (3.7%). The proportions of FD-ICSI derived zygotes at 12 hpic showing an RM<0.6 (60.6 and 62.4% for +4 and -196 C storage, respectively) were higher than that of the FT-ICSI derived zygotes (39.4%; P<0.05). Thus, the bovine paternal genome rapidly demethylated within 10 h after IVF and 6 h after ICSI, and the freeze-drying and/or the storage process had no adverse effect on demethylation of the paternal genome. The extent of demethylation in the pronuclear-stage bovine zygotes was moderate, with 0.4≤RM<0.6. Key words: Bovine zygotes, Demethylation, Freeze-drying, Intracytoplasmic sperm injection (ICSI), In vitro fertilization (IVF) (J. Reprod. Dev. 55: [433][434][435][436][437][438][439] 2009) pigenetic modification of DNA itself (methylation of cytosine in the dinucleotide CpG) and/or associated proteins (phosphorylation, acetylation and methylation of histone) are responsible for regulation of gene expression without changing the DNA consequences [1]. Methylation of the DNA is one of the best-studied epigenetic mechanisms, and it is recognized as a principle contributor to the stability of gene expression state [2]. The genomic methylation pattern is generally stable and heritable in differentiated somatic cells; however, genome-wide reprogramming has been reported to occur in germ cells and preimplantation embryos [3]. The reprogramming process includes erasing the existing epigenetic marks and re-establishing new cell-specific marks to generate cells with nuclear totipotency and broad developmental potential [3,4]. The biological importance of DNA methylation is still unclear [5], but aberrant epigenetic reprogramming, which has been reported in cattle and buffalo zygotes reconstructed with somatic cells [6][7][8], has been considered as a possible cause for higher incidence of gestational and neonatal fetal anomalies or deaths of such zygotes. Moreover,...

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“…These hypotheses may be supported by some findings as demethylation of multiple male pronuclei occurred in polyspermic fertilized mouse and human zygotes, while maternal genome in parthenogenetic, gynogenetic or triploid digynic zygotes did not demethylate [15,35]. In addition, bovine oocytes fail to actively demethylate the somatic cell nucleus [14] and abnormal pattern of paternal genome active demethylation was observed after ROSI in mouse [36][37][38]. However, active demethylation was noticed in bovine somatic cell nuclear-transferred zygotes [17].…”

Section: How the Maternal Genome Escape The Active Demethylation Procmentioning

confidence: 90%

“…Neither IVF nor ICSI protocol affected the dynamics of the active demethylation in the mouse [60], but ROSI protocol induced some abnormal dynamics such as insufficient demethylation level and occurrence of re-methylation [36][37][38]. So, it was supposed that the properties of paternal gamete may affect the efficiency of the active demethylation process [57].…”

Section: Effect Of In Vitro Embryo Production On Active Demethylationmentioning

confidence: 99%

Active Demethylation of Paternal Genome in Mammalian Zygotes

Abdalla

Yoshizawa

Hochi

2009

Journal of Reproduction and Development

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Abstract. Epigenetic reprogramming in early preimplantation embryos, that refers to erasing and remodeling epigenetic marks such as DNA methylation, is essential for differentiation and development. In many species, paternal genome is subjected to genome-wide active demethylation before the DNA replication commences, while maternal genome maintains its methylation status until being demethylated passively during the subsequent cleavage divisions. The purpose of this manuscript was to review the available knowledge about the paternal genome active demethylation process concerning the possible mechanisms, species variation and the factors affecting the active demethylation dynamics such as in vitro protocols for production of pronuclear-stage zygotes. Better understanding the mechanisms by which the epigenetic reprogramming is occurred may contribute to clarify the biological significance of this process. Key words: Active demethylation, Epigenetics, Paternal genome, Pronuclear zygotes (J. Reprod. Dev. 55: [356][357][358][359][360] 2009) ene expression is regulated by both genetic and epigenetic mechanisms. Epigenetics includes modifications of DNA itself (methylation of cytosine in the CpG dinucleotide) and/or the associated protein (phosphorylation, acetylation and methylation of histone) [1]. These modifications can regulate the gene expression without changing the DNA consequences [2]. Each cell type in our body has its own epigenetic signature which reflects different gene expression, and subsequently results in different structure and function among genetically homogenous cells. DNA methylation is one of the most-studied epigenetic mechanisms, and it is recognized as a chief contributor to the stability of gene expression state [3]. DNA Methylation: Nature, Function and ReprogrammingDNA methylation is a process that includes transferring a methyl group from S-adenosylmethionine to C5 positions of the cytosine residues in the CpG dinucleotides by different categories of methyltransferase enzymes (Dnmt1, Dnmt1o, Dnmt2, Dnmt3a, Dnmt3b and Dnmt3L) [4,5]. The CpG dinucleotides are mainly present in a cluster called CpG islands, which are associated with genes, and mostly located in promoters and first exons [6]. These islands are defined as the initiation sites for both transcription and DNA replication, and may represent genomic footprints for replication initiation [7]. Methylation of the CpG dinucleotides in the gene promoter may repress gene expression by interfering with the access of the DNA binding proteins and subsequently blocking the transcription or by binding to the transcriptional repressor MeCP2 [4,8,9]. In spite of great correlation between gene methylation status and gene expression, it is not yet clear whether DNA methylation is the cause of or a subsequence to the transcriptional repression [10]. In an another view for the correlation between gene methylation status and its expression, methylation can increase or decrease the level of gene transcription depending on whether the methylation in...

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Hypomethylation of paternal DNA in the late mouse zygote is not essential for development

Cited by 37 publications

References 17 publications

Pronuclear epigenetic modification of protamine deficient human sperm following injection into mouse oocytes

Pronuclear epigenetic modification of protamine deficient human sperm following injection into mouse oocytes

Demethylation Dynamics of the Paternal Genome in Pronuclear-Stage Bovine Zygotes Produced by In Vitro Fertilization and Ooplasmic Injection of Freeze-Thawed or Freeze-Dried Spermatozoa

Active Demethylation of Paternal Genome in Mammalian Zygotes

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