101
|
Rajender S, Avery K, Agarwal A. Epigenetics, spermatogenesis and male infertility. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2011; 727:62-71. [DOI: 10.1016/j.mrrev.2011.04.002] [Citation(s) in RCA: 206] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 04/07/2011] [Accepted: 04/08/2011] [Indexed: 12/31/2022]
|
102
|
Milroy C, Liu L, Hammoud S, Hammoud A, Peterson CM, Carrell DT. Differential methylation of pluripotency gene promoters in in vitro matured and vitrified, in vivo-matured mouse oocytes. Fertil Steril 2011; 95:2094-9. [PMID: 21457962 DOI: 10.1016/j.fertnstert.2011.02.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Revised: 02/02/2011] [Accepted: 02/03/2011] [Indexed: 12/12/2022]
Abstract
OBJECTIVE To assess the methylation patterns of four pluripotency gene promoters in mouse oocytes after in vivo maturation, in vitro maturation (IVM), and vitrification followed by IVM. DESIGN Experimental study. SETTING Research laboratory. ANIMAL(S) Three populations of metaphase II mouse oocytes were analyzed after in vivo maturation, IVM, and vitrification followed by IVM (V-IVM). Cumulus cells and blastocyst embryos were controls. INTERVENTION(S) The CpG methylation patterns (overall and CpG specific) in the promoters of four pluripotency genes (Oct4, Nanog, Foxd3, and Sox2) were analyzed for each cell type by traditional DNA bisulfite sequencing. MAIN OUTCOME MEASURE(S) Differences for overall methylation were evaluated using the Student's t-test and for individual CpG sites by χ2 analysis. RESULT(S) Significantly lower levels of overall methylation in promoters of Oct4 (25%) and Sox2 (4.5%) were noted in V-IVM oocytes compared with in vivo-matured oocytes (62.5% and 8.5%, respectively). Cumulus cell promoters were generally hypomethylated at Nanog, Foxd3. and Sox2, but hypermethylated at Oct4. CONCLUSION(S) The methylation status of Oct4 and Sox2 promoters of V-IVM mouse oocytes are altered when compared with in vivo-matured oocytes. The biological risk and significance of these changes are unknown and this study indicates caution and that further analyses are warranted.
Collapse
Affiliation(s)
- Colleen Milroy
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, School of Medicine, University of Utah, Salt Lake City, Utah 84108, USA
| | | | | | | | | | | |
Collapse
|
103
|
Liang XW, Ge ZJ, Wei L, Guo L, Han ZM, Schatten H, Sun QY. The effects of postovulatory aging of mouse oocytes on methylation and expression of imprinted genes at mid-term gestation. Mol Hum Reprod 2011; 17:562-7. [DOI: 10.1093/molehr/gar018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
|
104
|
Senner CE. The role of DNA methylation in mammalian development. Reprod Biomed Online 2011; 22:529-35. [PMID: 21498123 DOI: 10.1016/j.rbmo.2011.02.016] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 02/25/2011] [Accepted: 02/28/2011] [Indexed: 01/12/2023]
Abstract
DNA methylation is involved in a number of important processes such as maintaining genome stability, silencing of retrotransposons, co-ordinating mono-alleleic expression of parentally imprinted genes and ensuring transcriptional repression of genes on the inactive X chromosome. Further, correct DNA methylation patterns are necessary for normal development and lineage commitment. DNA methylation provides a stable and heritable epigenetic mark. However, it can be removed, either actively or passively, during periods of reprogramming in primordial germ cells and preimplantation embryos. By combining immunofluorescence data with recent insights from genome-wide studies utilizing techniques such as Bisulphite-seq and MeDIP-ChIP, a clearer picture of the dynamic patterns of DNA methylation throughout gametogenesis, preimplantation development and early lineage commitment is beginning to emerge. The continuing use of these next-generation technologies to elucidate genome-wide methylation patterns in a variety of cellular contexts will further understanding of how this epigenetic mark contributes to lineage commitment, differentiation and pluripotency and, ultimately, to human health and disease.
Collapse
Affiliation(s)
- Claire E Senner
- Laboratory of Epigenetics, The Babraham Institute, Babraham Research Campus, Cambridge, UK.
| |
Collapse
|
105
|
Stouder C, Somm E, Paoloni-Giacobino A. Prenatal exposure to ethanol: a specific effect on the H19 gene in sperm. Reprod Toxicol 2011; 31:507-12. [PMID: 21382472 DOI: 10.1016/j.reprotox.2011.02.009] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Revised: 01/17/2011] [Accepted: 02/28/2011] [Indexed: 02/01/2023]
Abstract
Alcohol exposure during pregnancy induces a range of disorders in the offspring. Methylation changes in imprinted genes may play a role in the teratogenic effects of alcohol. We evaluated the possible effects of alcohol administration in pregnant mice on the methylation pattern of 5 imprinted genes (H19, Gtl2, Peg1, Snrpn and Peg3) in somatic and sperm cell DNAs of the male offspring. The effects observed were a 3% (p < 0.005) decrease in the number of methylated CpGs of H19 in the F1 offspring sperm, a 4% (p < 0.005) decrease in the number of methylated CpGs of H19 in the F2 offspring brain and a 26% (p < 0.05) decrease in the mean sperm concentration. CpGs 1 and 2 of the H19 CTCF-binding site 2 exhibited significant methylation percentage losses. H19 CTCF-binding sites are important for the regulation of Igf2 gene expression. The hypomethylation of H19 may contribute to the decreased spermatogenesis in the offspring.
Collapse
Affiliation(s)
- Christelle Stouder
- Department of Genetic and Laboratory Medicine, Geneva University Hospital, 1211 Geneva 14, Switzerland
| | | | | |
Collapse
|
106
|
Hyldig SMW, Croxall N, Contreras DA, Thomsen PD, Alberio R. Epigenetic reprogramming in the porcine germ line. BMC DEVELOPMENTAL BIOLOGY 2011; 11:11. [PMID: 21352525 PMCID: PMC3051914 DOI: 10.1186/1471-213x-11-11] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Accepted: 02/25/2011] [Indexed: 11/16/2022]
Abstract
Background Epigenetic reprogramming is critical for genome regulation during germ line development. Genome-wide demethylation in mouse primordial germ cells (PGC) is a unique reprogramming event essential for erasing epigenetic memory and preventing the transmission of epimutations to the next generation. In addition to DNA demethylation, PGC are subject to a major reprogramming of histone marks, and many of these changes are concurrent with a cell cycle arrest in the G2 phase. There is limited information on how well conserved these events are in mammals. Here we report on the dynamic reprogramming of DNA methylation at CpGs of imprinted loci and DNA repeats, and the global changes in H3K27me3 and H3K9me2 in the developing germ line of the domestic pig. Results Our results show loss of DNA methylation in PGC colonizing the genital ridges. Analysis of IGF2-H19 regulatory region showed a gradual demethylation between E22-E42. In contrast, DMR2 of IGF2R was already demethylated in male PGC by E22. In females, IGF2R demethylation was delayed until E29-31, and was de novo methylated by E42. DNA repeats were gradually demethylated from E25 to E29-31, and became de novo methylated by E42. Analysis of histone marks showed strong H3K27me3 staining in migratory PGC between E15 and E21. In contrast, H3K9me2 signal was low in PGC by E15 and completely erased by E21. Cell cycle analysis of gonadal PGC (E22-31) showed a typical pattern of cycling cells, however, migrating PGC (E17) showed an increased proportion of cells in G2. Conclusions Our study demonstrates that epigenetic reprogramming occurs in pig migratory and gonadal PGC, and establishes the window of time for the occurrence of these events. Reprogramming of histone H3K9me2 and H3K27me3 detected between E15-E21 precedes the dynamic DNA demethylation at imprinted loci and DNA repeats between E22-E42. Our findings demonstrate that major epigenetic reprogramming in the pig germ line follows the overall dynamics shown in mice, suggesting that epigenetic reprogramming of germ cells is conserved in mammals. A better understanding of the sequential reprogramming of PGC in the pig will facilitate the derivation of embryonic germ cells in this species.
Collapse
Affiliation(s)
- Sara M W Hyldig
- Division of Animal Sciences, School of Biosciences, University of Nottingham, Loughborough, LE12 5RD, UK.
| | | | | | | | | |
Collapse
|
107
|
Li Y, Sasaki H. Genomic imprinting in mammals: its life cycle, molecular mechanisms and reprogramming. Cell Res 2011; 21:466-73. [PMID: 21283132 DOI: 10.1038/cr.2011.15] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Genomic imprinting, an epigenetic gene-marking phenomenon that occurs in the germline, leads to parental-origin-specific expression of a small subset of genes in mammals. Imprinting has a great impact on normal mammalian development, fetal growth, metabolism and adult behavior. The epigenetic imprints regarding the parental origin are established during male and female gametogenesis, passed to the zygote through fertilization, maintained throughout development and adult life, and erased in primordial germ cells before the new imprints are set. In this review, we focus on the recent discoveries on the mechanisms involved in the reprogramming and maintenance of the imprints. We also discuss the epigenetic changes that occur at imprinted loci in induced pluripotent stem cells.
Collapse
Affiliation(s)
- Yufeng Li
- Division of Epigenomics, Department of Molecular Genetics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | | |
Collapse
|
108
|
Rivera RM. Epigenetic aspects of fertilization and preimplantation development in mammals: lessons from the mouse. Syst Biol Reprod Med 2011; 56:388-404. [PMID: 20849224 DOI: 10.3109/19396368.2010.482726] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
During gametogenesis, the parental genomes are separated and are epigenetically marked by modifications that will direct the expression profile of genes necessary for meiosis as well as for the formation of the oocyte and sperm cell. Immediately after sperm-egg fusion, the parental haploid genomes show great epigenetic asymmetry with differences in the levels of DNA methylation and histone tail modifications. The epigenetic program acquired during oogenesis and spermatogenesis must be reset for the zygote to successfully proceed through preimplantation development and this occurs as the two genomes approach each other in preparation for karyogamy. During preimplantation development, the embryo is vested with the responsibility of maintaining the primary imprints. In addition, female embryos must silence one of the X-chromosomes in order to transcribe equal levels of X-linked genes as their male counterparts. This review is intended as a survey of the epigenetic modifications and mechanisms present in zygotes and preimplantation mouse embryos, namely DNA methylation, histone modifications, dosage compensation, genomic imprinting, and regulation by non-coding RNAs.
Collapse
|
109
|
Germ Cell Cancer, Testicular Dysgenesis Syndrome and Epigenetics. EPIGENETICS AND HUMAN REPRODUCTION 2011. [DOI: 10.1007/978-3-642-14773-9_2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
|
110
|
Fernández-Medarde A, Santos E. The RasGrf family of mammalian guanine nucleotide exchange factors. Biochim Biophys Acta Rev Cancer 2010; 1815:170-88. [PMID: 21111786 DOI: 10.1016/j.bbcan.2010.11.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Accepted: 11/14/2010] [Indexed: 12/31/2022]
Abstract
RasGrf1 and RasGrf2 are highly homologous mammalian guanine nucleotide exchange factors which are able to activate specific Ras or Rho GTPases. The RasGrf genes are preferentially expressed in the central nervous system, although specific expression of either locus may also occur elsewhere. RasGrf1 is a paternally-expressed, imprinted gene that is expressed only after birth. In contrast, RasGrf2 is not imprinted and shows a wider expression pattern. A variety of isoforms for both genes are also detectable in different cellular contexts. The RasGrf proteins exhibit modular structures composed by multiple domains including CDC25H and DHPH motifs responsible for promoting GDP/GTP exchange, respectively, on Ras or Rho GTPase targets. The various domains are essential to define their intrinsic exchanger activity and to modulate the specificity of their functional activity so as to connect different upstream signals to various downstream targets and cellular responses. Despite their homology, RasGrf1 and RasGrf2 display differing target specificities and non overlapping functional roles in a variety of signaling contexts related to cell growth and differentiation as well as neuronal excitability and response or synaptic plasticity. Whereas both RasGrfs are activatable by glutamate receptors, G-protein-coupled receptors or changes in intracellular calcium concentration, only RasGrf1 is reported to be activated by LPA, cAMP, or agonist-activated Trk and cannabinoid receptors. Analysis of various knockout mice strains has uncovered a specific functional contribution of RasGrf1 in processes of memory and learning, photoreception, control of post-natal growth and body size and pancreatic β-cell function and glucose homeostasis. For RasGrf2, specific roles in lymphocyte proliferation, T-cell signaling responses and lymphomagenesis have been described.
Collapse
|
111
|
CTCF-dependent chromatin bias constitutes transient epigenetic memory of the mother at the H19-Igf2 imprinting control region in prospermatogonia. PLoS Genet 2010; 6:e1001224. [PMID: 21124827 PMCID: PMC2991272 DOI: 10.1371/journal.pgen.1001224] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Accepted: 10/27/2010] [Indexed: 12/23/2022] Open
Abstract
Genomic imprints—parental allele-specific DNA methylation marks at the differentially methylated regions (DMRs) of imprinted genes—are erased and reestablished in germ cells according to the individual's sex. Imprint establishment at paternally methylated germ line DMRs occurs in fetal male germ cells. In prospermatogonia, the two unmethylated alleles exhibit different rates of de novo methylation at the H19/Igf2 imprinting control region (ICR) depending on parental origin. We investigated the nature of this epigenetic memory using bisulfite sequencing and allele-specific ChIP–SNuPE assays. We found that the chromatin composition in fetal germ cells was biased at the ICR between the two alleles with the maternally inherited allele exhibiting more H3K4me3 and less H3K9me3 than the paternally inherited allele. We determined genetically that the chromatin bias, and also the delayed methylation establishment in the maternal allele, depended on functional CTCF insulator binding sites in the ICR. Our data suggest that, in primordial germ cells, maternally inherited allele-specific CTCF binding sets up allele-specific chromatin differences at the ICR. The erasure of these allele-specific chromatin marks is not complete before the process of de novo methylation imprint establishment begins. CTCF–dependent allele-specific chromatin composition imposes a maternal allele-specific delay on de novo methylation imprint establishment at the H19/Igf2 ICR in prospermatogonia. Allele-specific DNA methylation is considered the primary mark that distinguishes the parental alleles of imprinted genes. Whereas allele-specific chromatin also exists at imprinted genes in the soma, this has not been assessed in the germ line. It will be important to understand what extent the chromatin composition provides clues in the germ line to the erasure and establishment of methylation imprints. Our novel methods provide the sensitivity required to answer these questions. Our results argue that the erasure of the DNA methylation imprint is complete before, and therefore does not depend on, the erasure of allele-specific chromatin marks at the H19/Igf2 imprint control region. Additionally, we show that incomplete erasure of the allele-specific chromatin is responsible for the delayed DNA methylation imprint establishment of the maternal ICR allele in prospermatogonia. The chromatin bias—the transient epigenetic memory of the mother—in fetal germ cells depends on functional CTCF insulator binding sites in this imprint control region.
Collapse
|
112
|
Stouder C, Paoloni-Giacobino A. Specific transgenerational imprinting effects of the endocrine disruptor methoxychlor on male gametes. Reproduction 2010; 141:207-16. [PMID: 21062904 DOI: 10.1530/rep-10-0400] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Endocrine-disrupting chemicals (EDCs), among which methoxychlor (MXC), have been reported to affect the male reproductive system. This study evaluates the possible deleterious effects of MXC on imprinted genes. After administration of the chemical in adult male mice or in pregnant mice we analyzed by pyrosequencing possible methylation defects in two paternally imprinted (H19 and Meg3 (Gtl2)) and three maternally imprinted (Mest (Peg1), Snrpn, and Peg3) genes in the sperm and in the tail, liver, and skeletal muscle DNAs of the adult male mice and of the male offspring. MXC treatment of adult mice decreased the percentages of methylated CpGs of Meg3 and increased those of Mest, Snrpn, and Peg3 in the sperm DNA. MXC treatment of pregnant mice decreased the mean sperm concentrations by 30% and altered the methylation pattern of all the imprinted genes tested in the F1 offspring. In the latter case, MXC effects were transgenerational but disappeared gradually from F1 to F3. MXC did not affect imprinting in the somatic cells, suggesting that it exerts its damaging effects via the process of reprogramming that is unique to gamete development. A systematic analysis at the CpG level showed a heterogeneity in the CpG sensitivity to MXC. This observation suggests that not only DNA methylation but also other epigenetic modifications can explain the transgenerational effects of MXC. The reported effects of EDCs on human male spermatogenesis might be mediated by complex imprinting alterations analogous to those described in this study.
Collapse
Affiliation(s)
- Christelle Stouder
- Department of Genetic and Laboratory Medicine, Geneva University Hospital, 1211 Geneva 14, Switzerland
| | | |
Collapse
|
113
|
Shoemaker R, Wang W, Zhang K. Mediators and dynamics of DNA methylation. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2010; 3:281-98. [PMID: 20878927 DOI: 10.1002/wsbm.124] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
As an inherited epigenetic marker occurring mainly on cytosines at CpG dinucleotides, DNA methylation occurs across many higher eukaryotic organisms. Looking at methylation patterns genome-wide classifies cell types uniquely and in several cases discriminates between healthy and cancerous cell types. DNA methylation can occur allele-specifically, which allows the cellular regulatory machinery to recognize each allele separately. Although only a small number of allele specifically methylated (ASM) regions are known, genome-wide experiments show that ASM is prevalent throughout the human genome. These DNA methylation patterns can be modified via DNA demethylation, which is important for induced pluripotent stem reprogramming and primordial germ cells. Recent evidence shows that the protein activation-induced cytidine deaminase plays a critical role in these demethylation events. Many transcription factors mediate DNA methylation patterns. Some transcription factors bind specifically to methylated or unmethylated sequences and other transcription factors protect genomic regions (e.g., promoter regions) from nearby DNA methylation encroachment. Possibly acting as another epigenetic regulatory layer, methylated cytosines are also converted to 5-hydroxyethylcyotines, which is a new modification type whose biological significance has yet been defined.
Collapse
Affiliation(s)
- Robert Shoemaker
- Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, CA, USA
| | | | | |
Collapse
|
114
|
Ollikainen M, Smith KR, Joo EJH, Ng HK, Andronikos R, Novakovic B, Abdul Aziz NK, Carlin JB, Morley R, Saffery R, Craig JM. DNA methylation analysis of multiple tissues from newborn twins reveals both genetic and intrauterine components to variation in the human neonatal epigenome. Hum Mol Genet 2010; 19:4176-88. [PMID: 20699328 DOI: 10.1093/hmg/ddq336] [Citation(s) in RCA: 267] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mounting evidence from both animal and human studies suggests that the epigenome is in constant drift over the life course in response to stochastic and environmental factors. In humans, this has been highlighted by a small number of studies that have demonstrated discordant DNA methylation patterns in adolescent or adult monozygotic (MZ) twin pairs. However, to date, it remains unclear when such differences emerge, and how prevalent they are across different tissues. To address this, we examined the methylation of four differentially methylated regions associated with the IGF2/H19 locus in multiple birth tissues derived from 91 twin pairs: 56 MZ and 35 dizygotic (DZ). Tissues included cord blood-derived mononuclear cells and granulocytes, human umbilical vein endothelial cells, buccal epithelial cells and placental tissue. Considerable variation in DNA methylation was observed between tissues and between unrelated individuals. Most interestingly, methylation discordance was also present within twin pairs, with DZ pairs showing greater discordance than MZ pairs. These data highlight the variable contribution of both intrauterine environmental exposures and underlying genetic factors to the establishment of the neonatal epigenome of different tissues and confirm the intrauterine period as a sensitive time for the establishment of epigenetic variability in humans. This has implications for the effects of maternal environment on the development of the newborn epigenome and supports an epigenetic mechanism for the previously described phenomenon of 'fetal programming' of disease risk.
Collapse
Affiliation(s)
- Miina Ollikainen
- Developmental Epigenetics, Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Victoria 3052, Australia
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
115
|
Santos F, Hyslop L, Stojkovic P, Leary C, Murdoch A, Reik W, Stojkovic M, Herbert M, Dean W. Evaluation of epigenetic marks in human embryos derived from IVF and ICSI. Hum Reprod 2010; 25:2387-95. [PMID: 20634187 DOI: 10.1093/humrep/deq151] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND It has long been appreciated that environmental cues may trigger adaptive responses. Many of these responses are a result of changes in the epigenetic landscape influencing transcriptional states and consequently altering phenotypes. In the context of human reproductive health, the procedures necessary for assisted reproduction may result in altered phenotypes by primarily influencing DNA methylation. Among the well-documented effects of assisted reproduction technologies (ART), imprinted genes appear to be frequently altered, likely owing to their reliance on DNA methylation to impose parent-specific monoallelic expression. However, the generality of the potential deregulation of DNA methylation in ART-derived human embryos has not been evaluated. METHODS In this study, we evaluate the genome-wide DNA methylation together with chromatin organisation in human embryos derived by either IVF (n = 89) or ICSI (n = 76). DNA methylation was assessed using an antibody against 5-methyl-cytidine, and chromatin organisation by DNA staining. RESULTS Irrespective of the ART procedure, similar errors were observed in both groups and abnormal chromatin was positively correlated (P < 0.001) with inappropriate DNA methylation. Development up to the blastocyst stage was consistent with normal DNA methylation and chromatin organisation, reinforcing the importance of epigenetic regulation to form the early lineages of the blastocyst. Most importantly, we found no evidence that ICSI blastocysts were more severely affected than those derived by IVF. CONCLUSIONS We conclude that ICSI does not lead to an increased incidence of epigenetic errors (DNA methylation and chromatin) compared with IVF.
Collapse
Affiliation(s)
- Fátima Santos
- The Laboratory of Developmental Genetics and Imprinting, Babraham Research Campus, Cambridge CB22 3AT, UK
| | | | | | | | | | | | | | | | | |
Collapse
|
116
|
Abstract
Primordial germ cells (PGCs) are embryonic progenitors for the gametes. In the gastrulating mouse embryo, a small group of cells begin expressing a unique set of genes and so commit to the germline. Over the next 3-5 days, these PGCs migrate anteriorly and increase rapidly in number via mitotic division before colonizing the newly formed gonads. PGCs then express a different set of unique genes, their inherited epigenetic imprint is erased and an individual methylation imprint is established, and for female PGCs, the silent X chromosome is reactivated. At this point, germ cells (GCs) commit to either a female or male sexual lineage, denoted by meiosis entry and mitotic arrest, respectively. This developmental program is determined by cues emanating from the somatic environment.
Collapse
Affiliation(s)
- Katherine A Ewen
- Division of Molecular Genetics and Development, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | | |
Collapse
|
117
|
Chan D, Cushnie DW, Neaga OR, Lawrance AK, Rozen R, Trasler JM. Strain-specific defects in testicular development and sperm epigenetic patterns in 5,10-methylenetetrahydrofolate reductase-deficient mice. Endocrinology 2010; 151:3363-73. [PMID: 20444942 DOI: 10.1210/en.2009-1340] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Methylenetetrahydrofolate reductase (MTHFR) is a crucial folate pathway enzyme that contributes to the maintenance of cellular pools of S-adenosylmethionine, the universal methyl donor for several reactions including DNA methylation. Whereas Mthfr(-/-) BALB/c mice show growth retardation, developmental delay, and spermatogenic defects and infertility, C57BL/6 mice appear to have a less severe phenotype. In the present study, we investigated the effects of MTHFR deficiency on early germ cell development in both strains and assessed whether MTHFR deficiency results in DNA methylation abnormalities in sperm. The reproductive phenotype associated with MTHFR deficiency differed strikingly between the two strains, with BALB/c mice showing an early postnatal loss of germ cell number and proliferation that was not evident in the C57BL/6 mice. As a result, the BALB/c MTHFR-deficient mice were infertile, whereas the C57BL/6 mice had decreased sperm numbers and altered testicular histology but showed normal fertility. Imprinted genes and sequences that normally become methylated during spermatogenesis were unaffected by MTHFR deficiency in C57BL/6 mice. In contrast, a genome-wide restriction landmark genomic scanning approach revealed a number of sites of hypo- and hypermethylation in the sperm of this mouse strain. These results showing strain-specific defects in MTHFR-deficient mice may help to explain population differences in infertility among men with common MTHFR polymorphisms.
Collapse
Affiliation(s)
- Donovan Chan
- Montréal Children's Hospital Research Institute, 2300 Tupper Street, Montréal, Québec, Canada H3H 1P3
| | | | | | | | | | | |
Collapse
|
118
|
Lee SH, Appleby V, Jeyapalan JN, Palmer RD, Nicholson JC, Sottile V, Gao E, Coleman N, Scotting PJ. Variable methylation of the imprinted gene, SNRPN, supports a relationship between intracranial germ cell tumours and neural stem cells. J Neurooncol 2010; 101:419-28. [DOI: 10.1007/s11060-010-0275-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Accepted: 06/16/2010] [Indexed: 12/14/2022]
|
119
|
Alterations in the developing testis transcriptome following embryonic vinclozolin exposure. Reprod Toxicol 2010; 30:353-64. [PMID: 20566332 DOI: 10.1016/j.reprotox.2010.05.086] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Revised: 04/17/2010] [Accepted: 05/28/2010] [Indexed: 12/31/2022]
Abstract
The current study investigates the direct effects of in utero vinclozolin exposure on the developing F1 generation rat testis transcriptome. Previous studies have demonstrated that exposure to vinclozolin during embryonic gonadal sex determination induces epigenetic modifications of the germ line and transgenerational adult onset disease states. Microarray analyses were performed to compare control and vinclozolin treated testis transcriptomes at embryonic days 13, 14 and 16. A total of 576 differentially expressed genes were identified and the major cellular functions and pathways associated with these altered transcripts were examined. The sets of regulated genes at the different development periods were found to be transiently altered and distinct. Categorization by major known functions of altered genes was performed. Specific cellular process and pathway analyses suggest the involvement of Wnt and calcium signaling, vascular development and epigenetic mechanisms as potential mediators of the direct F1 generation actions of vinclozolin.
Collapse
|
120
|
Hiura H, Sugawara A, Ogawa H, John RM, Miyauchi N, Miyanari Y, Horiike T, Li Y, Yaegashi N, Sasaki H, Kono T, Arima T. A tripartite paternally methylated region within the Gpr1-Zdbf2 imprinted domain on mouse chromosome 1 identified by meDIP-on-chip. Nucleic Acids Res 2010; 38:4929-45. [PMID: 20385583 PMCID: PMC2926594 DOI: 10.1093/nar/gkq200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The parent-of-origin specific expression of imprinted genes relies on DNA methylation of CpG-dinucleotides at differentially methylated regions (DMRs) during gametogenesis. To date, four paternally methylated DMRs have been identified in screens based on conventional approaches. These DMRs are linked to the imprinted genes H19, Gtl2 (IG-DMR), Rasgrf1 and, most recently, Zdbf2 which encodes zinc finger, DBF-type containing 2. In this study, we applied a novel methylated-DNA immunoprecipitation-on-chip (meDIP-on-chip) method to genomic DNA from mouse parthenogenetic- and androgenetic-derived stem cells and sperm and identified 458 putative DMRs. This included the majority of known DMRs. We further characterized the paternally methylated Zdbf2/ZDBF2 DMR. In mice, this extensive germ line DMR spanned 16 kb and possessed an unusual tripartite structure. Methylation was dependent on DNA methyltransferase 3a (Dnmt3a), similar to H19 DMR and IG-DMR. In both humans and mice, the adjacent gene, Gpr1/GPR1, which encodes a G-protein-coupled receptor 1 protein with transmembrane domain, was also imprinted and paternally expressed. The Gpr1-Zdbf2 domain was most similar to the Rasgrf1 domain as both DNA methylation and the actively expressed allele were in cis on the paternal chromosome. This work demonstrates the effectiveness of meDIP-on-chip as a technique for identifying DMRs.
Collapse
Affiliation(s)
- Hitoshi Hiura
- Innovation of New Biomedical Engineering Center, University of Tohoku, Aoba-ku, Sendai, Japan
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
121
|
Kim JM, Ogura A. Changes in allele-specific association of histone modifications at the imprinting control regions during mouse preimplantation development. Genesis 2010; 47:611-6. [PMID: 19530139 DOI: 10.1002/dvg.20541] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Allele-specific association of histone modification is observed at the regulatory region of imprinted genes and has been suggested to work as an epigenetic marker for monoallelic gene expression, along with the allelic CpG methylation of DNA. Although the parent-origin-specific epigenetic status in imprinted genes is thought to be established during preimplantation development, little is known about the allelic specificity of histone modifications during this period because of the limited volume of material available for analysis. In this study, we first revealed the allelic enrichment of histone modifications and variant histones at the imprinting control regions (ICRs) of four-cell to blastocyst stage preimplantation embryos by using carrier chromatin immunoprecipitation and sequence polymorphism analysis of immunoprecipitated DNA. We found relative enrichment of histone H3 lysine 9 dimethylation at the imprinted alleles of ICRs and obtained the results suggesting that histone modifications at ICRs are established during a late preimplantation stage.
Collapse
Affiliation(s)
- Jin-Moon Kim
- RIKEN Bioresource Center, Tsukuba, Ibaraki, Japan
| | | |
Collapse
|
122
|
H19 imprinting control region methylation requires an imprinted environment only in the male germ line. Mol Cell Biol 2009; 30:1108-15. [PMID: 20038532 DOI: 10.1128/mcb.00575-09] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The 2.4-kb H19 imprinting control region (H19ICR) is required to establish parent-of-origin-specific epigenetic marks and expression patterns at the Igf2/H19 locus. H19ICR activity is regulated by DNA methylation. The ICR is methylated in sperm but not in oocytes, and this paternal chromosome-specific methylation is maintained throughout development. We recently showed that the H19ICR can work as an ICR even when inserted into the normally nonimprinted alpha fetoprotein locus. Paternal but not maternal copies of the ICR become methylated in somatic tissue. However, the ectopic ICR remains unmethylated in sperm. To extend these findings and investigate the mechanisms that lead to methylation of the H19ICR in the male germ line, we characterized novel mouse knock-in lines. Our data confirm that the 2.4-kb element is an autonomously acting ICR whose function is not dependent on germ line methylation. Ectopic ICRs become methylated in the male germ line, but the timing of methylation is influenced by the insertion site and by additional genetic information. Our results support the idea that DNA methylation is not the primary genomic imprint and that the H19ICR insertion is sufficient to transmit parent-of-origin-dependent DNA methylation patterns independent of its methylation status in sperm.
Collapse
|
123
|
Identification of a region of the DNMT1 methyltransferase that regulates the maintenance of genomic imprints. Proc Natl Acad Sci U S A 2009; 106:20806-11. [PMID: 19923434 DOI: 10.1073/pnas.0905668106] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Reprogramming of DNA methylation patterns during mammalian preimplantation development involves the concurrent maintenance of methylation on differentially methylated domains (DMDs) of imprinted genes and a marked reduction of global (non-DMD) genomic methylation. In the developing mammalian embryo, one allele of a DMD is unmethylated, and the opposite parental allele is methylated, having inherited this methylation from the parental gamete. The maintenance of DMDs is important for monoallelic imprinted gene expression and normal development of the embryo. Because the DNMT1 cytosine methyltransferase governs maintenance methylation in mammals, rearrangements of non-DMD, but not DMD methylation in preimplantation embryos suggest that the preimplantation DNMT1-dependent maintenance mechanism specifically targets DMD sequences. We explored this possibility using an engineered mouse ES cell line to screen for mutant DNMT1 proteins that protect against the loss of DMD and/or global (non-DMD) methylation in the absence of the wild-type endogenous DNMT1 methyltransferase. We identified DNMT1 mutants that were defective in maintenance of either DMD and/or non-DMD methylation. Among these, one mutant maintained non-DMD methylation but not imprinted DMD methylation and another mutant maintained just DMD methylation. The mutated amino acids of these mutants reside in a mammal-specific, disordered region near the amino terminus of DNMT1. These findings suggest that DNMT1 participates in epigenetic reprogramming through its ability to distinguish different categories of methylated sequences.
Collapse
|
124
|
Abstract
The profound architectural changes that transform spermatids into spermatozoa result in a high degree of DNA packaging within the sperm head. However, the mature sperm chromatin that harbors imprinted genes exhibits a dual nucleoprotamine/nucleohistone structure with DNase-sensitive regions, which could be implicated in the establishment of efficient epigenetic information in the developing embryo. Despite its apparent transcriptionally inert state, the sperm nucleus contains diverse RNA populations, mRNAs, antisense and miRNAs, that have been transcribed throughout spermatogenesis. There is also an endogenous reverse transcriptase that may be activated under certain circumstances. It is now commonly accepted that sperm can deliver some RNAs to the ovocyte at fertilization. This review presents potential links between male-specific genomic imprinting, chromatin organization, and the presence of diverse RNA populations within the sperm nucleus and discusses the functional significance of these RNAs in the spermatozoon itself and in the early embryo following fertilization. Some recent data are provided, supporting the view that analyzing the profile of spermatozoal RNAs could be useful for assessment of male fertility.
Collapse
|
125
|
Stouder C, Paoloni-Giacobino A. Transgenerational effects of the endocrine disruptor vinclozolin on the methylation pattern of imprinted genes in the mouse sperm. Reproduction 2009; 139:373-9. [PMID: 19887539 DOI: 10.1530/rep-09-0340] [Citation(s) in RCA: 215] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Endocrine-disrupting chemicals (EDCs), among which is the antiandrogen vinclozolin (VCZ), have been reported to affect the male reproductive system. In this study, VCZ was administered to pregnant mice at the time of embryo sex determination, and its possible effects on the differentially methylated domains (DMDs) of two paternally (H19 and Gtl2) and three maternally (Peg1, Snrpn, and Peg3) imprinted genes were tested in the male offspring. The CpGs methylation status within the five gene DMDs was analyzed in the sperm, tail, liver, and skeletal muscle DNAs by pyrosequencing. In the sperm of controls, the percentages of methylated CpGs were close to the theoretical values of 100 and 0% in paternally or maternally imprinted genes respectively. VCZ decreased the percentages of methylated CpGs of H19 and Gtl2 (respective values 83.1 and 91.5%) and increased those of Peg1, Snrpn, and Peg3 (respective values 11.3, 18.3, and 11.2%). The effects of VCZ were transgenerational, but they disappeared gradually from F1 to F3. The mean sperm concentration of the VCZ-administered female offspring was only 56% of that of the controls in the F1 offspring, and it was back to normal values in the F2 and F3 offspring. In the somatic cells of controls, the percentages of methylated CpGs were close to the theoretical value of 50% and, surprisingly, VCZ altered the methylation of Peg3. We propose that the deleterious effects of VCZ on the male reproductive system are mediated by imprinting defects in the sperm. The reported effects of EDCs on human male spermatogenesis might be mediated by analogous imprinting alterations.
Collapse
Affiliation(s)
- Christelle Stouder
- Department of Genetic Medicine and Development Swiss Center for Applied Human Toxicology, University of Geneva Medical School, CMU, 1 Michel-Servet, 1211 Geneva 4, Switzerland
| | | |
Collapse
|
126
|
Guibert S, Forné T, Weber M. Dynamic regulation of DNA methylation during mammalian development. Epigenomics 2009; 1:81-98. [DOI: 10.2217/epi.09.5] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
DNA methylation occurs on cytosines, is catalyzed by DNA methyltransferases (DNMTs), and is present at high levels in all vertebrates. DNA methylation plays essential roles in maintaining genome integrity, but its implication in orchestrating gene-expression patterns remained a matter of debate for a long time. Recent efforts to map DNA methylation at the genome level helped to get a better picture of the distribution of this mark and revealed that DNA methylation is more dynamic between cell types than previously anticipated. In particular, these datasets showed that DNA methylation is targeted to important developmental genes and might act as a barrier to prevent accidental cellular reprogramming. In this review, we will discuss the distribution and function of DNA methylation in mammalian genomes, with particular emphasis on the waves of global DNA methylation reprogramming occurring in early embryos and primordial germ cells.
Collapse
Affiliation(s)
- Sylvain Guibert
- Institute of Molecular Genetics, CNRS UMR 5535, 1919 Route de Mende, 34293 Montpellier Cedex 5, France
| | - Thierry Forné
- Institute of Molecular Genetics, CNRS UMR 5535, 1919 Route de Mende, 34293 Montpellier Cedex 5, France
| | - Michael Weber
- Institute of Molecular Genetics, CNRS UMR 5535, 1919 Route de Mende, 34293 Montpellier Cedex 5, France
| |
Collapse
|
127
|
Abstract
Genomic imprinting refers to an epigenetic mark that distinguishes parental alleles and results in a monoallelic, parental-specific expression pattern in mammals. Few phenomena in nature depend more on epigenetic mechanisms while at the same time evading them. The alleles of imprinted genes are marked epigenetically at discrete elements termed imprinting control regions (ICRs) with their parental origin in gametes through the use of DNA methylation, at the very least. Imprinted gene expression is subsequently maintained using noncoding RNAs, histone modifications, insulators, and higher-order chromatin structure. Avoidance is manifest when imprinted genes evade the genome-wide reprogramming that occurs after fertilization and remain marked with their parental origin. This review summarizes what is known about the establishment and maintenance of imprinting marks and discusses the mechanisms of imprinting in clusters. Additionally, the evolution of imprinted gene clusters is described. While considerable information regarding epigenetic control of imprinting has been obtained recently, much remains to be learned.
Collapse
Affiliation(s)
- Marisa S Bartolomei
- Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
| |
Collapse
|
128
|
Dupont C, Armant DR, Brenner CA. Epigenetics: definition, mechanisms and clinical perspective. Semin Reprod Med 2009; 27:351-7. [PMID: 19711245 DOI: 10.1055/s-0029-1237423] [Citation(s) in RCA: 387] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
A vast array of successive epigenetic modifications ensures the creation of a healthy individual. Crucial epigenetic reprogramming events occur during germ cell development and early embryogenesis in mammals. As highlighted by the large offspring syndrome with in vitro conceived ovine and bovine animals, any disturbance during germ cell development or early embryogenesis has the potential to alter epigenetic reprogramming. Therefore the complete array of human assisted reproductive technology (ART), starting from ovarian hormonal stimulation to embryo uterine transfer, could have a profound impact on the epigenetic state of human in vitro produced individuals. Although some investigators have suggested an increased incidence of epigenetic abnormalities in in vitro conceived children, other researchers have refuted these allegations. To date, multiple reasons can be hypothesized why irrefutable epigenetic alterations as a result of ART have not been demonstrated yet.
Collapse
Affiliation(s)
- Cathérine Dupont
- Departments of Obstetrics & Gynecology, Wayne State University, Detroit, Michigan 48201, USA
| | | | | |
Collapse
|
129
|
Stouder C, Deutsch S, Paoloni-Giacobino A. Superovulation in mice alters the methylation pattern of imprinted genes in the sperm of the offspring. Reprod Toxicol 2009; 28:536-41. [PMID: 19549566 DOI: 10.1016/j.reprotox.2009.06.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Revised: 06/09/2009] [Accepted: 06/12/2009] [Indexed: 10/20/2022]
Abstract
Some steps of the assisted reproduction techniques, such as superovulation, may interfere with imprinting reprogramming. In the present study, superovulation was induced in the mouse and its possible effects on the differentially methylated domains of 2 paternally (H19 and Gtl2) and 3 maternally (Peg1, Snrpn and Peg3) imprinted genes were tested in the male offspring over 2 generations. The CpGs methylation status was analyzed by pyro- and bisulfite sequencing. In liver, skeletal muscle and tail, no effect of superovulation could be observed. In the sperm, however, a significant 6% decrease in the number of methylated CpGs of H19 and significant 2.8- and 7.0-fold increases in those of Peg1 and Snrpn, respectively were observed following superovulation. The changes were still present in the H19 and Snrpn genes of the second generation offspring. This suggests that superovulation in the mother transgenerationally affects the offspring sperm methylation pattern.
Collapse
Affiliation(s)
- Christelle Stouder
- Department of Genetic Medicine and Development, Geneva University Medical School, Geneva, Switzerland
| | | | | |
Collapse
|
130
|
Haston KM, Tung JY, Reijo Pera RA. Dazl functions in maintenance of pluripotency and genetic and epigenetic programs of differentiation in mouse primordial germ cells in vivo and in vitro. PLoS One 2009; 4:e5654. [PMID: 19468308 PMCID: PMC2681483 DOI: 10.1371/journal.pone.0005654] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Accepted: 04/27/2009] [Indexed: 11/19/2022] Open
Abstract
Background Mammalian germ cells progress through a unique developmental program that encompasses proliferation and migration of the nascent primordial germ cell (PGC) population, reprogramming of nuclear DNA to reset imprinted gene expression, and differentiation of mature gametes. Little is known of the genes that regulate quantitative and qualitative aspects of early mammalian germ cell development both in vivo, and during differentiation of germ cells from mouse embryonic stem cells (mESCs) in vitro. Methodology and Principal Findings We used a transgenic mouse system that enabled isolation of small numbers of Oct4ΔPE:GFP-positive germ cells in vivo, and following differentiation from mESCs in vitro, to uncover quantitate and qualitative phenotypes associated with the disruption of a single translational regulator, Dazl. We demonstrate that disruption of Dazl results in a post-migratory, pre-meiotic reduction in PGC number accompanied by aberrant expression of pluripotency genes and failure to erase and re-establish genomic imprints in isolated male and female PGCs, as well as subsequent defect in progression through meiosis. Moreover, the phenotypes observed in vivo were mirrored by those in vitro, with inability of isolated mutant PGCs to establish pluripotent EG (embryonic germ) cell lines and few residual Oct-4-expressing cells remaining after somatic differentiation of mESCs carrying a Dazl null mutation. Finally, we observed that even within undifferentiated mESCs, a nascent germ cell subpopulation exists that was effectively eliminated with ablation of Dazl. Conclusions and Significance This report establishes the translational regulator Dazl as a component of pluripotency, genetic, and epigenetic programs at multiple time points of germ cell development in vivo and in vitro, and validates use of the ESC system to model and explore germ cell biology.
Collapse
Affiliation(s)
- Kelly M. Haston
- Institute for Stem Cell Biology & Regenerative Medicine, Department of Obstetrics and Gynecology, Stanford University School of Medicine, Palo Alto, California, United States of America
| | - Joyce Y. Tung
- Institute for Stem Cell Biology & Regenerative Medicine, Department of Obstetrics and Gynecology, Stanford University School of Medicine, Palo Alto, California, United States of America
| | - Renee A. Reijo Pera
- Institute for Stem Cell Biology & Regenerative Medicine, Department of Obstetrics and Gynecology, Stanford University School of Medicine, Palo Alto, California, United States of America
- * E-mail:
| |
Collapse
|
131
|
Kobayashi H, Yamada K, Morita S, Hiura H, Fukuda A, Kagami M, Ogata T, Hata K, Sotomaru Y, Kono T. Identification of the mouse paternally expressed imprinted gene Zdbf2 on chromosome 1 and its imprinted human homolog ZDBF2 on chromosome 2. Genomics 2009; 93:461-72. [DOI: 10.1016/j.ygeno.2008.12.012] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Revised: 12/30/2008] [Accepted: 12/30/2008] [Indexed: 12/20/2022]
|
132
|
Abstract
Full mammalian development typically requires genomes from both the oocyte and spermatozoon. Biparental reproduction is necessary because of parent-specific epigenetic modification of the genome during gametogenesis; that is, a maternal methylation imprint imposed during the oocyte growth period and a paternal methylation imprint imposed in pregonadal gonocytes. This leads to unequivalent expression of imprinted genes from the maternal and paternal alleles in embryos and individuals. It is possible to hypothesise that the maternal methylation imprint is necessary to prevent parthenogenesis, which extinguishes the opportunity for having descendents, whereas the paternal methylation imprint prevents parthenogenesis, ensuring that a paternal contribution is obligatory for any descendants. To date, there are several lines of direct evidence that the epigenetic modifications that occur during oocyte growth have a decisive effect on mammalian development. Using bimaternal embryos with two sets of maternal genomes, the present paper illustrates how parental methylation imprints are an obstacle to the progression of parthenogenesis.
Collapse
Affiliation(s)
- Tomohiro Kono
- Department of BioScience, Tokyo University of Agriculture, Setagaya-ku, Tokyo 156-8502, Japan.
| |
Collapse
|
133
|
Zechner U, Nolte J, Wolf M, Shirneshan K, Hajj NE, Weise D, Kaltwasser B, Zovoilis A, Haaf T, Engel W. Comparative methylation profiles and telomerase biology of mouse multipotent adult germline stem cells and embryonic stem cells. ACTA ACUST UNITED AC 2009; 15:345-53. [DOI: 10.1093/molehr/gap023] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
|
134
|
Petkov SG, Reh WA, Anderson GB. Methylation changes in porcine primordial germ cells. Mol Reprod Dev 2009; 76:22-30. [PMID: 18425774 DOI: 10.1002/mrd.20926] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Epigenetic re-programming is an important event in the development of primordial germ cells (PGC) into functional gametes, characterized by genome-wide erasure of DNA methylation and re-establishment of epigenetic marks, a process essential for restoration of the potential for totipotency. In this study changes in the methylation status of centromeric repeats and two IGF2-H19 differentially methylated domain (DMD) sequences were examined in porcine PGC between Days 24 and 31 of pregnancy. The methylation levels of centromeric repeats and IGF2-H19 DMD sequences decreased rapidly from Days 24 to 28 in both male and female PGC. At Days 30 and 31 of pregnancy centromeric repeats and IGF2-H19 DMD sequences acquired new methylation in male PGC, while in female PGC these sequences were completely demethylated by Day 30 and remained hypomethylated at Day 31. To characterize methylation changes that PGC undergo in culture, the methylation status of embryonic germ cells (EGCs) derived from PGC at Day 26 of pregnancy was examined. Centromeric repeats and IGF2-H19 DMD sequences were similarly methylated in both male and female EGC and hypermethylated in female EGC compared with female PGC at the same embryonic age. Our results show that, similar to murine PGC, porcine PGC undergo genome-wide DNA demethylation shortly after arrival in the genital ridges. When placed in culture porcine PGC terminate their demethylation program and may acquire new DNA methylation marks. To our knowledge, this is the first report regarding epigenetic re-programming of genital ridge PGC in the pig.
Collapse
Affiliation(s)
- Stoyan G Petkov
- Department of Animal Science, University of California, Davis, California 95616, USA.
| | | | | |
Collapse
|
135
|
Cheng Y, Wang K, Kellam LD, Lee YS, Liang CG, Han Z, Mtango NR, Latham KE. Effects of ooplasm manipulation on DNA methylation and growth of progeny in mice. Biol Reprod 2008; 80:464-72. [PMID: 19073997 DOI: 10.1095/biolreprod.108.073593] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
New techniques to boost male and female fertility are being pioneered at a rapid pace in fertility clinics to increase the efficiency of assisted reproduction methods in couples in which natural conception has not been achieved. This study investigates the possible epigenetic effects of ooplasm manipulation methods on postnatal growth and development using a mouse genetic model, with particular emphasis on the possible effects of intergenotype manipulations. We performed interstrain and control intrastrain maternal pronuclear transfers, metaphase-II spindle transfers, and ooplasm transfer between C57BL/6 and DBA/2 mice, and found no major, long-term growth defects or epigenetic abnormalities, in either males or females, associated with intergenotype transfers. Ooplasm transfer itself was associated with reduced viability, and additional subtle effects of ooplasm strain of origin were observed. Both inter- and intrastrain ooplasm transfer were associated with subtle, transient effects on growth early in life. We also performed inter- and intrastrain germinal vesicle transfers (GVTs). Interstrain GVT females, but not males, had significantly lower body weights at birth and thereafter compared with the intrastrain GVT and non-GVT controls. No GVT-associated changes were observed in DNA methylation of the Mup1, Rasgrf1, H19, Snrpn, or Peg3 genes, nor any difference in expression of the imprinted Rasgrf1, Igf2r, or Mest genes. These results indicate that some ooplasm manipulation procedures may exert subtle effects on growth early in life, while intergenotype GVT can result in significant growth deficiencies after birth.
Collapse
Affiliation(s)
- Yong Cheng
- The Fels Institute for Cancer Research and Molecular Biology, Temple University Medical School, Philadelphia, Pennsylvania, USA
| | | | | | | | | | | | | | | |
Collapse
|
136
|
Park CH, Kim HS, Lee SG, Lee CK. Methylation status of differentially methylated regions at Igf2/H19 locus in porcine gametes and preimplantation embryos. Genomics 2008; 93:179-86. [PMID: 18983907 DOI: 10.1016/j.ygeno.2008.10.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2008] [Revised: 10/01/2008] [Accepted: 10/03/2008] [Indexed: 01/09/2023]
Abstract
The aim of this study was to demonstrate how differential methylation imprints are established during porcine preimplantation embryo development. For the methylation analysis, the primers for the three Igf2/H19 DMRs were designed and based upon previously published sequences. The methylation marks of Igf2/H19 DMRs were analysed in sperm and MII oocytes with our results showing that these regions are fully methylated in sperm but remain unmethylated in MII oocytes. In order to identify the methylation pattern at the pronuclear stage, we indirectly compared the methylation profile of Igf2/H19 DMR3 in each zygote derived by in vitro fertilization, parthenogenesis, and androgenesis. Interestingly, this region was found to be differently methylated according to parental origins; DMR3 was hemimethylated in in vitro fertilized zygotes, fully methylated in parthenogenetic zygotes, and demethylated in androgenetic zygotes. These results indicate that the methylation mark of the paternal allele is erased by active demethylation, and that of the maternal one is de novo methylated. We further examined the methylation imprints of Igf2/H19 DMR3 during early embryonic development. The hemimethylated pattern as seen in zygotes fertilized in vitro was observed up to the 4-cell embryo stage. However, this mark was exclusively demethylated at the 8-cell stage and then restored at the morula stage. These results suggest that methylation imprints are established via dynamic changes during early embryonic development in porcine embryos.
Collapse
Affiliation(s)
- Chi-Hun Park
- Department of Agricultural Biotechnology, Seoul National University San 56-1 Shillim-dong Gwanak-gu, Seoul 151-921, Korea
| | | | | | | |
Collapse
|
137
|
In situ detection of methylated DNA by histo endonuclease-linked detection of methylated DNA sites: a new principle of analysis of DNA methylation. Histochem Cell Biol 2008; 130:917-25. [DOI: 10.1007/s00418-008-0487-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/31/2008] [Indexed: 11/25/2022]
|
138
|
Lees-Murdock DJ, Lau HT, Castrillon DH, De Felici M, Walsh CP. DNA methyltransferase loading, but not de novo methylation, is an oocyte-autonomous process stimulated by SCF signalling. Dev Biol 2008; 321:238-50. [DOI: 10.1016/j.ydbio.2008.06.024] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2007] [Revised: 05/02/2008] [Accepted: 06/14/2008] [Indexed: 11/28/2022]
|
139
|
Anway MD, Rekow SS, Skinner MK. Comparative anti-androgenic actions of vinclozolin and flutamide on transgenerational adult onset disease and spermatogenesis. Reprod Toxicol 2008; 26:100-6. [PMID: 18762243 DOI: 10.1016/j.reprotox.2008.07.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Revised: 07/01/2008] [Accepted: 07/09/2008] [Indexed: 10/21/2022]
Abstract
Exposure of gestating female rats to the anti-androgenic endocrine disruptor vinclozolin has been shown to induce transgenerational adult onset disease phenotypes. The current study, was designed to compare the actions of vinclozolin to the known anti-androgenic compound flutamide. The gestating female rats were exposed to intraperitoneal injections during embryonic day 8-14 (E8-E14) to 100mg/kg/day vinclozolin or flutamide at either 5mg or 20mg/kg/day. As previously observed, vinclozolin induced a transgenerational testis phenotype of increased spermatogenic cell apoptosis and decreased epididymal sperm number. In contrast, the flutamide exposures resulted in a testis phenotype of increased spermatogenic cell apoptosis and decreased epididymal sperm numbers in the F1 generation only, and not the F2 and F3 generation adult males. Interestingly, some of the low dose (5mg/kg) flutamide F2 generation offspring developed spinal agenesis and supernummery development (polymelia) of limbs. Although the actions of vinclozolin and flutamide appear similar in the F1 generation males, the transgenerational effects of vinclozolin do not appear to be acting through the same anti-androgenic mechanism as flutamide.
Collapse
Affiliation(s)
- Matthew D Anway
- Center for Reproductive Biology, School of Molecular Biosciences, Washington State University, Pullman, WA 99164-4234, USA.
| | | | | |
Collapse
|
140
|
Abstract
In recent years, it has become increasingly clear that epigenetic regulation of gene expression is critical during spermatogenesis. In this review, the epigenetic regulation and the consequences of its aberrant regulation during mitosis, meiosis and spermiogenesis are described. The current knowledge on epigenetic modifications that occur during male meiosis is discussed, with special attention on events that define meiotic sex chromosome inactivation. Finally, the recent studies focused on transgenerational and paternal effects in mice and humans are discussed. In many cases, these epigenetic effects resulted in impaired fertility and potentially long-ranging affects underlining the importance of research in this area.
Collapse
|
141
|
Genomic imprinting: a balance between antagonistic roles of parental chromosomes. Semin Cell Dev Biol 2008; 19:574-9. [PMID: 18718545 DOI: 10.1016/j.semcdb.2008.07.018] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Revised: 07/21/2008] [Accepted: 07/24/2008] [Indexed: 11/21/2022]
Abstract
Maternally and paternally derived chromosomes might be expected to contribute equally to the various cellular and developmental processes in placental mammals and flowering plants. However, this is not true even in the case of the self-pollinated plant, Arabidopsis, which has identical DNA sequences in both parental genomes. The reason for this is that some genes, called "imprinted genes", are expressed exclusively from paternally or maternally inherited chromosomes. As a result, parental chromosomes express a distinct set of genes and play different roles in biological processes. Here, we review and compare roles of genomic imprinting in flowering plants and placental mammals.
Collapse
|
142
|
Farthing CR, Ficz G, Ng RK, Chan CF, Andrews S, Dean W, Hemberger M, Reik W. Global mapping of DNA methylation in mouse promoters reveals epigenetic reprogramming of pluripotency genes. PLoS Genet 2008; 4:e1000116. [PMID: 18584034 PMCID: PMC2432031 DOI: 10.1371/journal.pgen.1000116] [Citation(s) in RCA: 260] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Accepted: 06/04/2008] [Indexed: 12/11/2022] Open
Abstract
DNA methylation patterns are reprogrammed in primordial germ cells and in preimplantation embryos by demethylation and subsequent de novo methylation. It has been suggested that epigenetic reprogramming may be necessary for the embryonic genome to return to a pluripotent state. We have carried out a genome-wide promoter analysis of DNA methylation in mouse embryonic stem (ES) cells, embryonic germ (EG) cells, sperm, trophoblast stem (TS) cells, and primary embryonic fibroblasts (pMEFs). Global clustering analysis shows that methylation patterns of ES cells, EG cells, and sperm are surprisingly similar, suggesting that while the sperm is a highly specialized cell type, its promoter epigenome is already largely reprogrammed and resembles a pluripotent state. Comparisons between pluripotent tissues and pMEFs reveal that a number of pluripotency related genes, including Nanog, Lefty1 and Tdgf1, as well as the nucleosome remodeller Smarcd1, are hypomethylated in stem cells and hypermethylated in differentiated cells. Differences in promoter methylation are associated with significant differences in transcription levels in more than 60% of genes analysed. Our comparative approach to promoter methylation thus identifies gene candidates for the regulation of pluripotency and epigenetic reprogramming. While the sperm genome is, overall, similarly methylated to that of ES and EG cells, there are some key exceptions, including Nanog and Lefty1, that are highly methylated in sperm. Nanog promoter methylation is erased by active and passive demethylation after fertilisation before expression commences in the morula. In ES cells the normally active Nanog promoter is silenced when targeted by de novo methylation. Our study suggests that reprogramming of promoter methylation is one of the key determinants of the epigenetic regulation of pluripotency genes. Epigenetic reprogramming in the germline prior to fertilisation and the reprogramming of key pluripotency genes in the early embryo is thus crucial for transmission of pluripotency.
Collapse
Affiliation(s)
- Cassandra R. Farthing
- Laboratory of Developmental Genetics and Imprinting, The Babraham Institute, Cambridge, United Kingdom
| | - Gabriella Ficz
- Laboratory of Developmental Genetics and Imprinting, The Babraham Institute, Cambridge, United Kingdom
| | - Ray Kit Ng
- Laboratory of Developmental Genetics and Imprinting, The Babraham Institute, Cambridge, United Kingdom
| | - Chun-Fung Chan
- Laboratory of Developmental Genetics and Imprinting, The Babraham Institute, Cambridge, United Kingdom
| | - Simon Andrews
- Bioinformatics Group, The Babraham Institute, Cambridge, United Kingdom
| | - Wendy Dean
- Laboratory of Developmental Genetics and Imprinting, The Babraham Institute, Cambridge, United Kingdom
| | - Myriam Hemberger
- Laboratory of Developmental Genetics and Imprinting, The Babraham Institute, Cambridge, United Kingdom
- Centre for Trophoblast Research, University of Cambridge, Cambridge, United Kingdom
| | - Wolf Reik
- Laboratory of Developmental Genetics and Imprinting, The Babraham Institute, Cambridge, United Kingdom
- Centre for Trophoblast Research, University of Cambridge, Cambridge, United Kingdom
- * E-mail:
| |
Collapse
|
143
|
Jiang H, Sun B, Wang W, Zhang Z, Gao F, Shi G, Cui B, Kong X, He Z, Ding X, Kuang Y, Fei J, Sun YJ, Feng Y, Jin Y. Activation of paternally expressed imprinted genes in newly derived germline-competent mouse parthenogenetic embryonic stem cell lines. Cell Res 2008; 17:792-803. [PMID: 17768400 DOI: 10.1038/cr.2007.70] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Parthenogenetic embryonic stem (pES) cells provide a valuable in vitro model system for studying the molecular mechanisms that underlie genomic imprinting. However, the pluripotency of pES cells and the expression profiles of paternally expressed imprinted genes have not been fully explored. In this study, three mouse pES cell lines were established and the differentiation potential of these cells in extended culture was evaluated. The undifferentiated cells had a normal karyotype and homozygous genome, and expressed ES-cell-specific molecular markers. The cells remained undifferentiated after more than 50 passages and exhibited pluripotent differentiation capacity. All three lines of the established ES cells produced teratomas; two lines of ES cells produced chimeras and germline transmission. Furthermore, activation of the paternally expressed imprinted genes Snrpn, U2af1-rs1, Peg3, Impact, Zfp127, Dlk1 and Mest in these cells was detected. Some paternally expressed imprinted genes were found to be expressed in the blastocyst stage of parthenogenetically activated embryos in vitro and their expression level increased with extended pES cell culture. Furthermore, our data show that the activation of these paternally expressed imprinted genes in pES cells was associated with a change in the methylation of the related differentially methylated regions. These findings provide direct evidence for the pluripotency of pES cells and demonstrate the association between the DNA methylation pattern and the activation of paternally expressed imprinted genes in pES cells. Thus, the established ES cell lines provide a valuable model for studying epigenetic regulation in mammalian development.
Collapse
Affiliation(s)
- Hua Jiang
- The Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences/Shanghai JiaoTong University School of Medicine, Shanghai, China
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
144
|
Baumann C, Schmidtmann A, Muegge K, De La Fuente R. Association of ATRX with pericentric heterochromatin and the Y chromosome of neonatal mouse spermatogonia. BMC Mol Biol 2008; 9:29. [PMID: 18366812 PMCID: PMC2275742 DOI: 10.1186/1471-2199-9-29] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2007] [Accepted: 03/13/2008] [Indexed: 11/10/2022] Open
Abstract
Background Establishment of chromosomal cytosine methylation and histone methylation patterns are critical epigenetic modifications required for heterochromatin formation in the mammalian genome. However, the nature of the primary signal(s) targeting DNA methylation at specific genomic regions is not clear. Notably, whether histone methylation and/or chromatin remodeling proteins play a role in the establishment of DNA methylation during gametogenesis is not known. The chromosomes of mouse neonatal spermatogonia display a unique pattern of 5-methyl cytosine staining whereby centromeric heterochromatin is hypo-methylated whereas chromatids are strongly methylated. Thus, in order to gain some insight into the relationship between global DNA and histone methylation in the germ line we have used neonatal spermatogonia as a model to determine whether these unique chromosomal DNA methylation patterns are also reflected by concomitant changes in histone methylation. Results Our results demonstrate that histone H3 tri-methylated at lysine 9 (H3K9me3), a hallmark of constitutive heterochromatin, as well as the chromatin remodeling protein ATRX remained associated with pericentric heterochromatin regions in spite of their extensive hypo-methylation. This suggests that in neonatal spermatogonia, chromosomal 5-methyl cytosine patterns are regulated independently of changes in histone methylation, potentially reflecting a crucial mechanism to maintain pericentric heterochromatin silencing. Furthermore, chromatin immunoprecipitation and fluorescence in situ hybridization, revealed that ATRX as well as H3K9me3 associate with Y chromosome-specific DNA sequences and decorate both arms of the Y chromosome, suggesting a possible role in heterochromatinization and the predominant transcriptional quiescence of this chromosome during spermatogenesis. Conclusion These results are consistent with a role for histone modifications and chromatin remodeling proteins such as ATRX in maintaining transcriptional repression at constitutive heterochromatin domains in the absence of 5-methyl cytosine and provide evidence suggesting that the establishment and/or maintenance of repressive histone and chromatin modifications at pericentric heterochromatin following genome-wide epigenetic reprogramming in the germ line may precede the establishment of chromosomal 5-methyl cytosine patterns as a genomic silencing strategy in neonatal spermatogonia.
Collapse
Affiliation(s)
- Claudia Baumann
- Female Germ Cell Biology Group, Department of Clinical Studies, Center for Animal Transgenesis and Germ Cell Research, School of Veterinary Medicine, University of Pennsylvania, New Bolton Center, Kennett Square, PA 19348, USA.
| | | | | | | |
Collapse
|
145
|
Anway MD, Skinner MK. Epigenetic programming of the germ line: effects of endocrine disruptors on the development of transgenerational disease. Reprod Biomed Online 2008; 16:23-5. [PMID: 18252044 DOI: 10.1016/s1472-6483(10)60553-6] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Epigenetic programming of the germ line occurs during embryonic development in a sex-specific manner. The male germ line becomes imprinted following sex determination. Environmental influences can alter this epigenetic programming and affect not only the developing offspring, but also potentially subsequent generations. Exposure to an endocrine disruptor (i.e. vinclozolin) during embryonic gonadal sex determination can alter the male germ-line epigenetics (e.g. DNA methylation). The epigenetic mechanism involves the alteration of DNA methylation in the germ line that appears to transmit transgenerational adult onset disease, including spermatogenic defects, prostate disease, kidney disease and cancer.
Collapse
Affiliation(s)
- Matthew D Anway
- Centre for Reproductive Biology, School of Molecular Biosciences, Washington State University, Pullman, WA 99164-4231, USA
| | | |
Collapse
|
146
|
Epigenetic events in mammalian germ-cell development: reprogramming and beyond. Nat Rev Genet 2008; 9:129-40. [PMID: 18197165 DOI: 10.1038/nrg2295] [Citation(s) in RCA: 600] [Impact Index Per Article: 37.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The epigenetic profile of germ cells, which is defined by modifications of DNA and chromatin, changes dynamically during their development. Many of the changes are associated with the acquisition of the capacity to support post-fertilization development. Our knowledge of this aspect has greatly increased- for example, insights into how the re-establishment of parental imprints is regulated. In addition, an emerging theme from recent studies is that epigenetic modifiers have key roles in germ-cell development itself--for example, epigenetics contributes to the gene-expression programme that is required for germ-cell development, regulation of meiosis and genomic integrity. Understanding epigenetic regulation in germ cells has implications for reproductive engineering technologies and human health.
Collapse
|
147
|
Bourc'his D, Proudhon C. Sexual dimorphism in parental imprint ontogeny and contribution to embryonic development. Mol Cell Endocrinol 2008; 282:87-94. [PMID: 18178305 DOI: 10.1016/j.mce.2007.11.025] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Genomic imprinting refers to the functional non-equivalence of parental genomes in mammals that results from the parent-of-origin allelic expression of a subset of genes. Parent-specific expression is dependent on the germ line acquisition of DNA methylation marks at imprinting control regions (ICRs), coordinated by the DNA-methyltransferase homolog DNMT3L. We discuss here how the gender-specific stages of DNMT3L expression may have influenced the various sexually dimorphic aspects of genomic imprinting: (1) the differential developmental timing of methylation establishment at paternally and maternally imprinted genes in each parental germ line, (2) the differential dependence on DNMT3L of parental methylation imprint establishment, (3) the unequal duration of paternal versus maternal methylation imprints during germ cell development, (4) the biased distribution of methylation-dependent ICRs towards the maternal genome, (5) the different genomic organization of paternal versus maternal ICRs, and finally (6) the overwhelming contribution of maternal germ line imprints to development compared to their paternal counterparts.
Collapse
Affiliation(s)
- Déborah Bourc'his
- INSERM U741, Paris 7 University, 2 Place Jussieu, 75251 Paris Cedex 05, France.
| | | |
Collapse
|
148
|
Marques CJ, Costa P, Vaz B, Carvalho F, Fernandes S, Barros A, Sousa M. Abnormal methylation of imprinted genes in human sperm is associated with oligozoospermia. Mol Hum Reprod 2008; 14:67-74. [PMID: 18178607 DOI: 10.1093/molehr/gam093] [Citation(s) in RCA: 279] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Genomic imprinting marks in the male germ line are already established in the adult germinal stem cell population. We studied the methylation patterns of H19 and MEST imprinted genes in sperm of control and oligozoospermic patients, by bisulphite genomic sequencing. We here report that 7 out of 15 (46.7%) patients with a sperm count below 10 x 10(6)/ml display defective methylation of H19 and/or MEST imprinted genes. In these cases, hypomethylation was observed in 5.54% (1.2-8.3%) and complete unmethylation in 2.95% (0-5.9%) of H19 clones. Similarly, for the CTCF-binding site 6, hypomethylation occurred in 4.8% (1.2-8.9%) and complete unmethylation in 3.7% (0-6.9%) of the clones. Conversely, hypermethylation occurred in 8.3% (3.8-12.2%) and complete methylation in 6.1% (3.8-7.6%) of MEST clones. Of the seven patients presenting imprinting errors, two had both H19 hypomethylation and MEST hypermethylation, whereas five displayed only one imprinted gene affected. The frequency of patients with MEST hypermethylation was highest in the severe oligozoospermia group (2/5 patients), whereas H19 hypomethylation was more frequent in the moderate oligozoospermia (2/5 patients). In all cases, global sperm genome methylation analysis (LINE1 transposon) suggested that defects were specific for imprinted genes. These findings could contribute to an explanation of the cause of Silver-Russell syndrome in children born with H19 hypomethylation after assisted reproductive technologies (ART). Additionally, unmethylation of the CTCF-binding site could lead to inactivation of the paternal IGF2 gene, and be linked to decreased embryo quality and birth weight, often associated with ART.
Collapse
Affiliation(s)
- C J Marques
- Department of Genetics, Faculty of Medicine, Porto 4200-319, Portugal
| | | | | | | | | | | | | |
Collapse
|
149
|
DNA methylation reprogramming in the germ line. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 626:1-15. [PMID: 18372787 DOI: 10.1007/978-0-387-77576-0_1] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
In mammals, methylation occurs almost exclusively on the CpG dinucleotide in DNA and shows no preference for sequence context surrounding this target. CpGs are found on many different sequence classes and methylation of this dinucleotide is associated with repression of transcription. Reprogramming methylation in the primordial germ cells establishes monoallelic expression of imprinted genes which exhibit monoallelic expression throughout the lifetime of an organism, maintains retrotransposons in an inactive state and inactivates one of the two X chromosomes. In addition to direct transcriptional silencing, DNA methylation is important for suppression of recombination, and resetting this information is therefore necessary for maintenance of genomic stability. In this chapter, we will review the recent progress in our understanding of the time course and extent of DNA methylation reprogramming of many different sequence classes. We focus on the mouse germline, since this has been the model system from which we have gained the most knowledge of the process. In addition we will examine some of the evidence suggesting a link between repeat methylation and methylation of epigenetically controlled single-copy genes. To do this, we will look at the temporal sequence of methylation events from the time the germ cells become recognizable as a discrete population until the mature male and female gametes fuse and form the early embryo.
Collapse
|
150
|
Houshdaran S, Cortessis VK, Siegmund K, Yang A, Laird PW, Sokol RZ. Widespread epigenetic abnormalities suggest a broad DNA methylation erasure defect in abnormal human sperm. PLoS One 2007; 2:e1289. [PMID: 18074014 PMCID: PMC2100168 DOI: 10.1371/journal.pone.0001289] [Citation(s) in RCA: 224] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Accepted: 10/28/2007] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Male-factor infertility is a common condition, and etiology is unknown for a high proportion of cases. Abnormal epigenetic programming of the germline is proposed as a possible mechanism compromising spermatogenesis of some men currently diagnosed with idiopathic infertility. During germ cell maturation and gametogenesis, cells of the germ line undergo extensive epigenetic reprogramming. This process involves widespread erasure of somatic-like patterns of DNA methylation followed by establishment of sex-specific patterns by de novo DNA methylation. Incomplete reprogramming of the male germ line could, in theory, result in both altered sperm DNA methylation and compromised spermatogenesis. METHODOLOGY/PRINCIPAL FINDING We determined concentration, motility and morphology of sperm in semen samples collected by male members of couples attending an infertility clinic. Using MethyLight and Illumina assays we measured methylation of DNA isolated from purified sperm from the same samples. Methylation at numerous sequences was elevated in DNA from poor quality sperm. CONCLUSIONS This is the first report of a broad epigenetic defect associated with abnormal semen parameters. Our results suggest that the underlying mechanism for these epigenetic changes may be improper erasure of DNA methylation during epigenetic reprogramming of the male germ line.
Collapse
Affiliation(s)
- Sahar Houshdaran
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Victoria K. Cortessis
- Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Kimberly Siegmund
- Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Allen Yang
- Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Peter W. Laird
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
- Department of Surgery, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Rebecca Z. Sokol
- Department of Obstetrics and Gynecology, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
- Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| |
Collapse
|