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Project description:BackgroundThe sperm DNA methylation landscape is unique and critical for offspring health. If gamete-derived DNA methylation escapes reprograming in early embryos, epigenetic defects in sperm may be transmitted to the next generation. Current techniques to assess sperm DNA methylation show bias toward CpG-dense regions and do not target areas of dynamic methylation, those predicted to be environmentally sensitive and tunable regulatory elements.ObjectivesOur goal was to assess variation in human sperm DNA methylation and design a targeted capture panel to interrogate the human sperm methylome.MethodsTo characterize variation in sperm DNA methylation, we performed whole genome bisulfite sequencing (WGBS) on an equimolar pool of sperm DNA from a wide cross section of 30 men varying in age, fertility status, methylenetetrahydrofolate reductase (MTHFR) genotype, and exposures. With our targeted capture panel, in individual samples, we examined the effect of MTHFR genotype ([Formula: see text] 677CC, [Formula: see text] 677TT), as well as high-dose folic acid supplementation ([Formula: see text], per genotype, before and after supplementation).ResultsThrough WGBS we discovered nearly 1 million CpGs possessing intermediate methylation levels (20-80%), termed dynamic sperm CpGs. These dynamic CpGs, along with 2 million commonly assessed CpGs, were used to customize a capture panel for targeted interrogation of the human sperm methylome and test its ability to detect effects of altered folate metabolism. As compared with MTHFR 677CC men, those with the 677TT genotype (50% decreased MTHFR activity) had both hyper- and hypomethylation in their sperm. High-dose folic acid supplement treatment exacerbated hypomethylation in MTHFR 677TT men compared with 677CC. In both cases, [Formula: see text] of altered methylation was found in dynamic sperm CpGs, uniquely measured by our assay.DiscussionOur sperm panel allowed the discovery of differential methylation following conditions affecting folate metabolism in novel dynamic sperm CpGs. Improved ability to examine variation in sperm DNA methylation can facilitate comprehensive studies of environment-epigenome interactions. https://doi.org/10.1289/EHP4812.
| S-EPMC6792365 | biostudies-literature
Project description:5,10-Methylenetetrahydrofolate reductase (MTHFR) is an enzyme that plays a key role in providing methyl groups for DNA methylation, including during spermatogenesis. A common genetic variant in humans (MTHFR 677C>T), results in reduced enzyme activity and has been linked to various disorders, including male infertility. A new animal model has been created by reproducing the human equivalent of the polymorphism in mice using CRISPR/Cas9. Biochemical parameters in the Mthfr 677TT mice recapitulate alterations found in MTHFR 677TT men. Our aims were to: 1) characterize the sperm DNA methylome of the Mthfr 677CC and TT mice on a control diet (2mg folic acid/kg diet) and 2) assess the effects of folic acid deficiency (0.3mg/kg diet) and supplementation (10 mg/kg diet) on the sperm DNA methylome. Body and reproductive organ weights, testicular sperm counts, and histology were examined. DNA methylation in sperm was assessed using bisulfite pyrosequencing, Illumina Mouse Methylation Array and whole genome bisulfite sequencing. Reproductive parameters and imprinted gene methylation were unaffected by genotype or diets. The largest effect was due to genotype, with sperm from 677TT mice showing more hypo- than hypermethylation. Folate-deficient diets resulted in sperm hyper- and hypomethylation in CC and TT mice. Folic acid supplementation caused mostly hypermethylation in sperm of males of both genotypes and was found to partially correct the DNA methylation alterations in sperm associated with the TT genotype. The new mouse model will be useful in understanding the role of MTHFR deficiency in male fertility and in designing folate supplementation regimens for the clinic.
2024-04-17 | GSE240712 | GEO
Project description:Genomic imprinting describes the expression of a subset of mammalian genes from one parental chromosome. The parent-of-origin specific expression of imprinted genes relies on DNA methylation of CpG-dinucleotides at differentially methylated regions (DMRs) during gametogenesis. We identified the paternally methylated DMR at human chromosome 2 near the imprinted ZDBF2 gene using a methylated-DNA immunoprecipitation-on-chip (meDIP-on-chip) method applied to DNA from sperm.
2010-05-05 | GSE18178 | GEO
Project description:Using whole-genome bisulfite sequencing (WGBS), we profiled the DNA methylome of cattle sperms through comparison with three bovine somatic tissues (mammary grand, brain and blood). Large differences between cattle sperms and somatic tissues were observed in the methylation patterns.
2018-03-08 | GSE106538 | GEO
Project description:5-methylcytosine is a major epigenetic modification sometimes called "the fifth nucleotide". However, our knowledge of how offspring inherit the DNA methylome from parents is limited. We generated nine single-base resolution DNA methylomes including zebrafish gametes and early embryos. The oocyte methylome is significantly hypo-methylated compared to sperm. Strikingly, the paternal DNA methylation pattern is maintained throughout early embryogenesis. The maternal DNA methylation pattern is maintained until the 16-cell stage. Then, the oocyte methylome is gradually discarded through cell division, and progressively reprogrammed to a pattern similar to that of the sperm methylome. The passive demethylation rate and the de novo methylation rate are similar in the maternal DNA. By the midblastula stage, the embryo?s methylome is virtually identical to the sperm methylome. Moreover, inheritance of the sperm methylome facilitates the epigenetic regulation of embryogenesis. Therefore, besides DNA sequences, sperm DNA methylome is also inherited in zebrafish early embryos.
2013-05-20 | GSE44075 | GEO
Project description:5-methylcytosine is a major epigenetic modification that is sometimes called "the fifth nucleotide." However, our knowledge of how offspring inherit the DNA methylome from parents is limited. We generated nine single-base resolution DNA methylomes, including zebrafish gametes and early embryos. The oocyte methylome is significantly hypomethylated compared to sperm. Strikingly, the paternal DNA methylation pattern is maintained throughout early embryogenesis. The maternal DNA methylation pattern is maintained until the 16-cell stage. Then, the oocyte methylome is gradually discarded through cell division and is progressively reprogrammed to a pattern similar to that of the sperm methylome. The passive demethylation rate and the de novo methylation rate are similar in the maternal DNA. By the midblastula stage, the embryo's methylome is virtually identical to the sperm methylome. Moreover, inheritance of the sperm methylome facilitates the epigenetic regulation of embryogenesis. Therefore, besides DNA sequences, sperm DNA methylome is also inherited in zebrafish early embryos.
| S-EPMC4081501 | biostudies-literature
Project description:It is now well understood that epigenetic alterations occur frequently in sporadic breast carcinogenesis, but little is known about the epigenetic alterations associated with familial breast tumors. We performed genome-wide DNA methylation profiling on familial breast cancers (n=33) to identify patterns of methylation specific to the different mutation groups (BRCA1, BRCA2 and BRCAx) or intrinsic subtypes of breast cancer (basal, luminal A, luminal B, HER2 and normal-like). We used methylated DNA immunoprecipitation (meDIP) on Affymetrix human promoter chips to interrogate methylation profiles across 25,500 distinct transcripts.
2010-03-12 | GSE17125 | GEO
Project description:Aim: To characterize the sperm methylome in semen samples from 19 donors with proven fertility. Material and Methods: Bisulfite-converted sperm DNA was hybridized on the HumanMethylation450 Infinium BeadChip platform. CpG fluorescence-intensities were extracted and converted to β-values. Results: The sperm methylome is highly homogeneous and hypomethylated. Genes with hypomethylated promoters are ontologically associated to biological functions related to spermatogenesis and embryogenesis. Sex-chromosomes are the most hypomethylated chromosomes, supporting data that indicated their essential role in spermatogenesis. Ninety-four genes are resistant to demethylation, being strong candidates for transgenerational inheritance. Conclusion: Spermatozoa carry a homogeneous methylation profile that is a footprint of past events (spermatogenesis), is designed to facilitate future events (embryogenesis), and has a possible influence in the adult life (transgenerational effects).
2018-05-01 | GSE99184 | GEO
Project description:Although autism spectrum disorder (ASD) is among the most heritable of neurodevelopmental disorders, the rapidly rising prevalence of ASD suggests that environmental factors may interact with genetic risk for ASD. Environmental factors may impact both gene expression and phenotypes in ASD through epigenetic modifications that, in turn, could lead to intergenerational effects influencing risk for ASDs. Endocrine disrupting compounds (EDCs), such as the long-lived organochlorines, are of particular interest with respect to risk for autism because of their ability to interfere with sex hormones that have been implicated in the regulation of RORA, a dysregulated gene in ASD that is a master regulator of many other ASD risk genes. The specific aims of this study are to: 1) investigate whether high versus low exposures to the persistent organochlorine 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) are associated with differentially methylated regions (DMRs) in sperm from a Faroese cohort whose natural diet of pilot whale meat and blubber exposes them to higher than average levels of organic pollutants; 2) determine if genes associated with DDE DMRs are enriched for ASD risk genes; 3) identify pathways and functions over-represented among genes associated with DMRs. Whole genome bisulfite sequencing (WGBS) was used to identify genome-wide DMRs in sperm from individuals divided by high and low exposure levels. Gene ontology and pathway analyses were used to determine enrichment in functional relationships to ASD. Genes in DMRs not only could discriminate between high and low exposures to DDE, but also were enriched in autism risk genes. Gene ontology and pathway analyses of these genes show significant enrichment for neurodevelopmental processes frequently impacted by ASD. Results of this study show that elevated exposure to certain organochlorines is associated with genome-wide DNA methylation patterns in sperm affecting genes involved in neurological functions and developmental disorders, including ASD.
2022-08-31 | GSE165915 | GEO
Project description:Study question: Do short-term and long-term exposures to low dose folic acid supplementation alter DNA methylation in sperm? Summary answer: No alterations in sperm DNA methylation patterns were found following the administration of low dose folic acid supplements of 400 μg/day for 90 days (short-term exposure) or when pre-fortification of food with folic acid and post-fortification sperm samples (long-term exposure) were compared. What is known already: Excess dietary folate may be detrimental to health and DNA methylation profiles due to folate’s role in one carbon metabolism and the formation of S-adenosyl methionine, the universal methyl donor. DNA methylation patterns are established in developing male germ cells and have been suggested to be affected by high dose (5 mg/day) folic acid supplementation. Participants/materials, setting, methods: Blood and seminal plasma folate levels were measured in participants before and following the 90-day treatment with placebo or supplement. Sperm DNA methylation was assessed using the whole genome and genome-wide techniques, MassArray epityper, restriction landmark genomic scanning, methyl-CpG immunoprecipitation and Illumina HumanMethylation450 Bead Array. Main results and the role of chance: Following treatment, supplemented individuals had significantly higher levels of blood and seminal plasma folates compared to placebo. Initial first generation genome-wide analyses of sperm DNA methylation showed little evidence of changes when comparing pre- and post-treatment samples. With Illumina HumanMethylation450 BeadChip arrays, no significant changes were observed in individual probes following low-level supplementation; when compared with those of the post-fortification cohort, there were also few differences in methylation despite exposure to years of fortified foods. Limitations, reasons for caution: This study was limited to the number of participants available in each cohort, in particular those who were not exposed to early (pre-1998) fortification of food with folic acid. While genome-wide DNA methylation was assessed with several techniques that targeted genic and CpG rich regions, intergenic regions were less well interrogated. Wider implications of the findings: Overall, our findings provide evidence that short term exposure to low dose folic acid supplements of 400 μg/day, over a period of 3 months, a duration of time that might occur during infertility treatments, has no major impact on the sperm DNA methylome.
2016-11-12 | GSE89781 | GEO