scholarly journals DNA Methylation Dynamics in the Female Germline and Maternal-Effect Mutations That Disrupt Genomic Imprinting

Genes ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1214
Author(s):  
Zahra Anvar ◽  
Imen Chakchouk ◽  
Hannah Demond ◽  
Momal Sharif ◽  
Gavin Kelsey ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Genomic Imprinting ◽  
Protein Complex ◽  
Hydatidiform Mole ◽  
Early Embryo ◽  
Monoallelic Expression ◽  
Pathogenic Variants ◽  
Imprinting Disorder ◽  
Embryonic Arrest ◽  
Female Germline

Genomic imprinting is an epigenetic marking process that results in the monoallelic expression of a subset of genes. Many of these ‘imprinted’ genes in mice and humans are involved in embryonic and extraembryonic growth and development, and some have life-long impacts on metabolism. During mammalian development, the genome undergoes waves of (re)programming of DNA methylation and other epigenetic marks. Disturbances in these events can cause imprinting disorders and compromise development. Multi-locus imprinting disturbance (MLID) is a condition by which imprinting defects touch more than one locus. Although most cases with MLID present with clinical features characteristic of one imprinting disorder. Imprinting defects also occur in ‘molar’ pregnancies-which are characterized by highly compromised embryonic development-and in other forms of reproductive compromise presenting clinically as infertility or early pregnancy loss. Pathogenic variants in some of the genes encoding proteins of the subcortical maternal complex (SCMC), a multi-protein complex in the mammalian oocyte, are responsible for a rare subgroup of moles, biparental complete hydatidiform mole (BiCHM), and other adverse reproductive outcomes which have been associated with altered imprinting status of the oocyte, embryo and/or placenta. The finding that defects in a cytoplasmic protein complex could have severe impacts on genomic methylation at critical times in gamete or early embryo development has wider implications beyond these relatively rare disorders. It signifies a potential for adverse maternal physiology, nutrition, or assisted reproduction to cause epigenetic defects at imprinted or other genes. Here, we review key milestones in DNA methylation patterning in the female germline and the embryo focusing on humans. We provide an overview of recent findings regarding DNA methylation deficits causing BiCHM, MLID, and early embryonic arrest. We also summarize identified SCMC mutations with regard to early embryonic arrest, BiCHM, and MLID.

Erasing genomic imprinting memory in mouse clone embryos produced from day 11.5 primordial germ cells

Development ◽  
2002 ◽  
Vol 129 (8) ◽  
pp. 1807-1817 ◽  
Author(s):  
Jiyoung Lee ◽  
Kimiko Inoue ◽  
Ryuichi Ono ◽  
Narumi Ogonuki ◽  
Takashi Kohda ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Genomic Imprinting ◽  
Nuclear Transfer ◽  
Monoallelic Expression ◽  
Parental Origin ◽  
Imprinted Genes ◽  
Specific Expression ◽  
Male And Female ◽  
Imprinted Gene ◽  
Methylation Patterns

Genomic imprinting is an epigenetic mechanism that causes functional differences between paternal and maternal genomes, and plays an essential role in mammalian development. Stage-specific changes in the DNA methylation patterns of imprinted genes suggest that their imprints are erased some time during the primordial germ cell (PGC) stage, before their gametic patterns are re-established during gametogenesis according to the sex of individuals. To define the exact timing and pattern of the erasure process, we have analyzed parental-origin-specific expression of imprinted genes and DNA methylation patterns of differentially methylated regions (DMRs) in embryos, each derived from a single day 11.5 to day 13.5 PGC by nuclear transfer. Cloned embryos produced from day 12.5 to day 13.5 PGCs showed growth retardation and early embryonic lethality around day 9.5. Imprinted genes lost their parental-origin-specific expression patterns completely and became biallelic or silenced. We confirmed that clones derived from both male and female PGCs gave the same result, demonstrating the existence of a common default state of genomic imprinting to male and female germlines. When we produced clone embryos from day 11.5 PGCs, their development was significantly improved, allowing them to survive until at least the day 11.5 embryonic stage. Interestingly, several intermediate states of genomic imprinting between somatic cell states and the default states were seen in these embryos. Loss of the monoallelic expression of imprinted genes proceeded in a step-wise manner coordinated specifically for each imprinted gene. DNA demethylation of the DMRs of the imprinted genes in exact accordance with the loss of their imprinted monoallelic expression was also observed. Analysis of DNA methylation in day 10.5 to day 12.5 PGCs demonstrated that PGC clones represented the DNA methylation status of donor PGCs well. These findings provide strong evidence that the erasure process of genomic imprinting memory proceeds in the day 10.5 to day 11.5 PGCs, with the timing precisely controlled for each imprinted gene. The nuclear transfer technique enabled us to analyze the imprinting status of each PGC and clearly demonstrated a close relationship between expression and DNA methylation patterns and the ability of imprinted genes to support development.

scholarly journals Genomic imprinting in germ cells: imprints are under control

Reproduction ◽  
2010 ◽  
Vol 140 (3) ◽  
pp. 411-423 ◽  
Author(s):  
Philippe Arnaud
Keyword(s):  
Dna Methylation ◽  
Genomic Imprinting ◽  
Germ Cells ◽  
Imprinted Genes ◽  
Regulatory Sequences ◽  
Sequence Specificity ◽  
Maternal Allele ◽  
Primary Sequence ◽  
Chromatin Configuration

The cis-acting regulatory sequences of imprinted gene loci, called imprinting control regions (ICRs), acquire specific imprint marks in germ cells, including DNA methylation. These epigenetic imprints ensure that imprinted genes are expressed exclusively from either the paternal or the maternal allele in offspring. The last few years have witnessed a rapid increase in studies on how and when ICRs become marked by and subsequently maintain such epigenetic modifications. These novel findings are summarised in this review, which focuses on the germline acquisition of DNA methylation imprints and particularly on the combined role of primary sequence specificity, chromatin configuration, non-histone proteins and transcriptional events.

An N-Ethyl-N-Nitrosourea Mutagenesis Screen for Epigenetic Mutations in the Mouse

Genetics ◽  
2003 ◽  
Vol 164 (4) ◽  
pp. 1481-1494
Author(s):  
Ivona Percec ◽  
Joanne L Thorvaldsen ◽  
Robert M Plenge ◽  
Christopher J Krapp ◽  
Joseph H Nadeau ◽  
...  
Keyword(s):  
Genomic Imprinting ◽  
X Chromosome ◽  
X Inactivation ◽  
Monoallelic Expression ◽  
Chromosome 15 ◽  
Chromosome 5 ◽  
Chromosome 10 ◽  
Mutagenesis Screen ◽  
Distal Chromosome ◽  
Males And Females

Abstract The mammalian epigenetic phenomena of X inactivation and genomic imprinting are incompletely understood. X inactivation equalizes X-linked expression between males and females by silencing genes on one X chromosome during female embryogenesis. Genomic imprinting functionally distinguishes the parental genomes, resulting in parent-specific monoallelic expression of particular genes. N-ethyl-N-nitrosourea (ENU) mutagenesis was used in the mouse to screen for mutations in novel factors involved in X inactivation. Previously, we reported mutant pedigrees identified through this screen that segregate aberrant X-inactivation phenotypes and we mapped the mutation in one pedigree to chromosome 15. We now have mapped two additional mutations to the distal chromosome 5 and the proximal chromosome 10 in a second pedigree and show that each of the mutations is sufficient to induce the mutant phenotype. We further show that the roles of these factors are specific to embryonic X inactivation as neither genomic imprinting of multiple genes nor imprinted X inactivation is perturbed. Finally, we used mice bearing selected X-linked alleles that regulate X chromosome choice to demonstrate that the phenotypes of all three mutations are consistent with models in which the mutations have affected molecules involved specifically in the choice or the initiation of X inactivation.

scholarly journals ZFP57 dictates allelic expression switch of target imprinted genes

2021 ◽  
Vol 118 (5) ◽  
pp. e2005377118
Author(s):  
Weijun Jiang ◽  
Jiajia Shi ◽  
Jingjie Zhao ◽  
Qiu Wang ◽  
Dan Cong ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Notch Signaling ◽  
Notch Pathway ◽  
Notch Signaling Pathway ◽  
Mouse Embryos ◽  
The Other ◽  
Allelic Expression ◽  
Monoallelic Expression ◽  
Imprinted Genes ◽  
Parent Of Origin

ZFP57 is a master regulator of genomic imprinting. It has both maternal and zygotic functions that are partially redundant in maintaining DNA methylation at some imprinting control regions (ICRs). In this study, we found that DNA methylation was lost at most known ICRs in Zfp57 mutant embryos. Furthermore, loss of ZFP57 caused loss of parent-of-origin–dependent monoallelic expression of the target imprinted genes. The allelic expression switch occurred in the ZFP57 target imprinted genes upon loss of differential DNA methylation at the ICRs in Zfp57 mutant embryos. Specifically, upon loss of ZFP57, the alleles of the imprinted genes located on the same chromosome with the originally methylated ICR switched their expression to mimic their counterparts on the other chromosome with unmethylated ICR. Consistent with our previous study, ZFP57 could regulate the NOTCH signaling pathway in mouse embryos by impacting allelic expression of a few regulators in the NOTCH pathway. In addition, the imprinted Dlk1 gene that has been implicated in the NOTCH pathway was significantly down-regulated in Zfp57 mutant embryos. Our allelic expression switch models apply to the examined target imprinted genes controlled by either maternally or paternally methylated ICRs. Our results support the view that ZFP57 controls imprinted expression of its target imprinted genes primarily through maintaining differential DNA methylation at the ICRs.

DNA methylation and genomic imprinting

Cell ◽  
1994 ◽  
Vol 77 (4) ◽  
pp. 473-476 ◽  
Author(s):  
Aharon Razin ◽  
Howard Cedar
Keyword(s):  
Dna Methylation ◽  
Genomic Imprinting

100 ASSESSMENT OF LOCUS-SPECIFIC DNA METHYLATION: OPTIMIZATION FOR BOVINE EMBRYOS

2009 ◽  
Vol 21 (1) ◽  
pp. 150
Author(s):  
E. Wroclawska ◽  
J. O. Brant ◽  
T. P. Yang ◽  
K. Moore
Keyword(s):  
Dna Methylation ◽  
Somatic Cell ◽  
Chromatin Remodeling ◽  
Plasmid Dna ◽  
Dna Amplification ◽  
Early Embryo ◽  
Small Samples ◽  
Small Scale ◽  
Research Education

Assessment of chromatin remodeling in early embryos is a major focus of studies today, and evaluation of DNA methylation at specific loci is one approach to study these epigenetic modifications. Our objective was to optimize the bisulfite sequencing methodology for use with very small cell numbers originating from pre-implantation embryos, making the process more time- and cost-efficient. The optimized steps include bisulfite conversion of small samples, bisulfite primer design, high-throughput plasmid DNA amplification, and preparation for sequencing. Methylation at 2 loci, Satellite I and Oct4, was investigated in bovine in vitro-produced (IVP) embryos collected at the 2-cell, 8-cell, and blastocyst stages. Bovine skin fibroblasts were first used to optimize the particular steps of the process. All reactions were run in duplicate and no-template negative and somatic cell-positive controls were treated alongside samples. Incorporating the use of Methyl Primer Express (Applied Biosystems, Foster City, CA), MacVector (Oxford Molecular Ltd., Campbell, CA), and Mfold software (Mathews DH et al. 1999 J. Mol. Biol. 288, 911–940; Zuker M 2003 Nucleic Acids Res. 31, 3406–3415) improved the specificity of bisulfite primers by exclusion of secondary or tertiary structures. The DNA from bisulfite treatment for 15 to 16 h was of better quality than DNA treated for 18 h. After initial PCR optimization, different cell concentrations were used to establish that detectable PCR products and subsequent methylation data could be obtained from DNA isolated from as few as 8 cells. Treating single blastocysts and pools of ten 8-cell and forty 2-cell embryos was sufficient for the entire scope of the experiment, allowing use of the same samples across all loci. After molecular cloning, plasmid DNA was amplified by 3 different methods and evaluated for efficiency: miniprep, TempliPhi (GE Healthcare, Piscataway, NJ), or 96-well glycerol stocks and automated TempliPhi format. Although TempliPhi alone was better than miniprep for small-scale experiments, it was the 96-well format that saved weeks of time and was most cost-effective. Sequencing was performed on a minimum of 8 clones/sample using ABI Prism sequencers (Applied Biosystems), and results were analyzed using Chromas Pro software (Technelysium Pty. Ltd., Helensvale, Australia). Percentage methylation of bovine IVP 2-cell, 8-cell, and blastocyst stage embryos for Satellite I was 25, 10, and 22%, respectively, and for Oct4 was 88, 88, and 79%, respectively. However, somatic cell methylation was 74% for Satellite I and 88% for Oct4, implying that Satellite I is demethylated during early embryo development, whereas Oct4 remains hypermethylated. In conclusion, these improved methods will benefit further studies of chromatin remodeling in early bovine pre-implantation embryos. This project was supported by National Research Initiative Competitive Grant no. 2006-35203-16620 from the USDA Cooperative State Research, Education, and Extension Service.

124. DNA METHYLATION IN THE 2-CELL MOUSE EMBRYO IS THE RESULT OF DNMT ACTIVITY DURING DEVELOPMENT FROM THE ZYGOTE TO THE 2-CELL STAGE

2009 ◽  
Vol 21 (9) ◽  
pp. 43
Author(s):  
Y. Li ◽  
H. D. Morgan ◽  
L. Ganeshan ◽  
C. O'Neill
Keyword(s):  
Dna Methylation ◽  
Dna Methyltransferase ◽  
Cytosine Methylation ◽  
De Novo ◽  
Culture Conditions ◽  
Early Embryo ◽  
Cleavage Stage ◽  
Cell Stage ◽  
Stage Of Development ◽  
First Time

In an accompanying abstract we show for the first time that global demethylation of both paternally- and maternally-derived genomes occurs prior to syngamy. It is commonly considered that new methylation of the genome does not commence until late in the preimplantation stage. Yet embryos during cleavage stage are known to show DNA methylation. This creates a paradox, if global demethylation occurs by the time of syngamy yet remethylation does not occur until the blastocysts stage, how can cleavage stage embryos possess methylated DNA. We examined this paradox. We examined DNA methylation in 2-cell embryos by confocal microscopy of anti-methylcytosine immunofluorescence and propidium iodide co-staining of whole mounts. We confirmed that DNA in late zygotes was substantially demethylated in both the male and female pronuclei. By the 2-cell stage, embryos collected direct from the oviduct showed high levels of cytosine methylation. We assessed whether this accumulation of cytosine methylation during the early 2-cell stage was a consequence of DNA methyltransferase (DNMT) activity. This was achieved by treating late stage zygotes with the DNMT inhibitor RG108 (5 μM) for the period of development spanning pronuclear stage 5 to early 2-cell stage. The embryos that developed in the presence of the DNA methyltransferase inhibitor showed significantly less methylcytosine staining than the embryos in the untreated culture conditions (P<0.001). Treatment of embryos during this period with RG108 significantly reduced their capacity to develop to normal blastocysts, indicating that this early DNA re-methylation reaction was important for the normal development of the embryo. Our results show for the first time that de novo methylation of the genome occurs as early as the 2-cell stage of development and that this is mediated by a RG108-sensitive DNMT activity. The results substantially change our understanding of epigenetic reprogramming in the early embryo.

scholarly journals DNA modifications in the mammalian brain

2014 ◽  
Vol 369 (1652) ◽  
pp. 20130512 ◽  
Author(s):  
Jaehoon Shin ◽  
Guo-li Ming ◽  
Hongjun Song
Keyword(s):  
Dna Methylation ◽  
Brain Development ◽  
Genomic Imprinting ◽  
Mammalian Brain ◽  
Epigenetic Mark ◽  
Mammalian Development ◽  
Dna Modifications ◽  
Dna Elements ◽  
And Function ◽  
Neuronal Functions

DNA methylation is a crucial epigenetic mark in mammalian development, genomic imprinting, X-inactivation, chromosomal stability and suppressing parasitic DNA elements. DNA methylation in neurons has also been suggested to play important roles for mammalian neuronal functions, and learning and memory. In this review, we first summarize recent discoveries and fundamental principles of DNA modifications in the general epigenetics field. We then describe the profiles of different DNA modifications in the mammalian brain genome. Finally, we discuss roles of DNA modifications in mammalian brain development and function.

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