Original Research Article Archives - Episona
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Obesity and Bariatric Surgery Drive Epigenetic Variation of Spermatozoa in Humans
Feb 2016 | Cell Metabolism
Ida Donkin, Soetkin Versteyhe, Lars R. Ingerslev, Kui Qian, Mie Mechta, Loa Nordkap, Brynjulf Mortensen, Emil Vincent R. Appel, Niels Jørgensen, Viggo B. Kristiansen, Torben Hansen, Christopher T. Workman, Juleen R. Zierath, Romain Barrès
Obesity is a heritable disorder, with children of obese fathers at higher risk of developing obesity. Environmental factors epigenetically influence somatic tissues, but the contribution of these factors to the establishment of epigenetic patterns in human gametes is unknown. Here, we hypothesized that weight loss remodels the epigenetic signature of spermatozoa in human obesity. <!--more-->Comprehensive profiling of the epigenome of sperm from lean and obese men showed similar histone positioning, but small non-coding RNA expression and DNA methylation patterns were markedly different. In a separate cohort of morbidly obese men, surgery-induced weight loss was associated with a dramatic remodeling of sperm DNA methylation, notably at genetic locations implicated in the central control of appetite. Our data provide evidence that the epigenome of human spermatozoa dynamically changes under environmental pressure and offers insight into how obesity may propagate metabolic dysfunction to the next generation.
Paternal Psychological Stress Reprograms Hepatic Gluconeogenesis in Offspring
Feb 2016 | Cell Metabolism
Ling Wu, Yan Lu, Yang Jiao, Bin Liu, Shangang Li, Yao Li, Fengying Xing, Dongbao Chen, Xing Liu, Jiejie Zhao, Xuelian Xiong, Yanyun Gu, Jieli Lu, Xuejin Chen, and Xiaoying Li
Both epidemiologic and experimental animal studies demonstrate that chronic psychological stress exerts adverse effects on the initiation and/or progression of many diseases. However, intergenerational effects of this environmental information remains poorly understood. Here, using a C57BL/6 mouse model of restraint stress, we show that offspring of stressed fathers exhibit hyperglycemia due to enhanced hepatic gluconeogenesis and elevated expression of PEPCK. <!--more-->Mechanistically, we identify an epigenetic alteration at the promoter region of the Sfmbt2 gene, a maternally imprinted polycomb gene, leading to a downregulation of intronic microRNA-466b-3p, which post-transcriptionally inhibits PEPCK expression. Importantly, hyperglycemia in F1 mice is reversed by RU486 treatment in fathers, and dexamethasone administration in F0 mice phenocopies the roles of restraint stress. Thus, we provide evidence showing the effects of paternal psychological stress on the regulation of glucose metabolism in offspring, which may have profound implications for our understanding of health and disease risk inherited from fathers.
Aberrant sperm DNA methylation predicts male fertility status and embryo quality
Dec 2015 | Fertility Sterility
Kenneth I. Aston, Philip J. Uren, Timothy G. Jenkins, Alan Horsager, Bradley R. Cairns, Andrew D. Smith, Douglas T. Carrell
To evaluate whether male fertility status and/or embryo quality during in vitro fertilization (IVF) therapy can be predicted based on genomewide sperm deoxyribonucleic acid (DNA) methylation patterns. Participants were 127 men undergoing IVF treatment (where any major female factor cause of infertility had been ruled out), and 54 normozoospermic, fertile men. The IVF patients were stratified into 2 groups: patients who had generally good embryogenesis and a positive pregnancy (n = 55), and patients with generally poor embryogenesis (n = 72; 42 positive and 30 negative pregnancies) after IVF. <!--more-->Genomewide sperm DNA methylation analysis was performed to measure methylation at >485,000 sites across the genome. A comparison was made of DNA methylation patterns of IVF patients vs. normozoospermic, fertile men. Predictive models proved to be highly accurate in classifying male fertility status (fertile or infertile), with 82% sensitivity, and 99% positive predictive value. Hierarchic clustering identified clusters enriched for IVF patient samples and for poor-quality-embryo samples. Models built to identify samples within these groups, from neat samples, achieved positive predictive value ≥94% while identifying >one fifth of all IVF patient and poor-quality-embryo samples in each case. Using density gradient prepared samples, the same approach recovered 46% of poor-quality-embryo samples with no false positives. Sperm DNA methylation patterns differ significantly and consistently for infertile vs. fertile, normozoospermic men. In addition, DNA methylation patterns may be predictive of embryo quality during IVF.
Methylation analysis of histone H4K12ac-associated promoters in sperm of healthy donors and subfertile patients
Mar 2015 -|Clinical Epigenetics
Markus Vieweg, Katerina Dvorakova-Hortova, Barbora Dudkova, Przemyslaw Waliszewski, Marie Otte, Berthold Oels, Amir Hajimohammad, Heiko Turley, Martin Schorsch, Hans-Christian Schuppe, Wolfgang Weidner, Klaus Steger, Agnieszka Paradowska-Dogan
Histone to protamine exchange and the hyperacetylation of the remaining histones are hallmarks of spermiogenesis. Acetylation of histone H4 at lysine 12 (H4K12ac) was observed prior to full decondensation of sperm chromatin after fertilization suggesting an important role for the regulation of gene expression in early embryogenesis. Similarly, DNA methylation may contribute to gene silencing of several developmentally important genes. <!--more-->Following the identification of H4K12ac-binding promoters in sperm of fertile and subfertile patients, we aimed to investigate whether the depletion of histone-binding is associated with aberrant DNA methylation in sperm of subfertile men. Furthermore, we monitored the transmission of H4K12ac, 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) from the paternal chromatin to the embryo applying mouse in vitro fertilization and immunofluorescence. Chromatin immunoprecipitation (ChIP) with anti-H4K12ac antibody was performed with chromatin isolated from spermatozoa of subfertile patients with impaired sperm chromatin condensation assessed by aniline blue staining. Fertile donors were used as control. DNA methylation analysis of selected H4K12ac-interacting promoters in spermatozoa was performed by pyrosequencing. Depletion of binding sites for H4K12ac was observed within the following developmentally important promoters: AFF4, EP300, LRP5, RUVBL1, USP9X, NCOA6, NSD1, and POU2F1. We found 5% to 10% hypomethylation within CpG islands of selected promoters in the sperm of fertile donors, and it was not significantly altered in the subfertile group. Our results demonstrate that the H4K12ac depletion in selected developmentally important promoters of subfertile patients was not accompanied by a change of DNA methylation. Using a murine model, immunofluorescence revealed that H4K12ac co-localize with 5mC in the sperm nucleus. During fertilization, when the pronuclei are formed, the paternal pronucleus exhibits a strong acetylation signal on H4K12, while in the maternal pronucleus, there is a permanent increase of H4K12ac until pronuclei fusion. Simultaneously, there is an increase of the 5hmC signal and a decrease of the 5mC signal. We suggest that aberrant histone acetylation within developmentally important gene promoters in subfertile men, but not DNA methylation, may reflect insufficient sperm chromatin compaction affecting the transfer of epigenetic marks to the oocyte.
Decreased fecundity and sperm DNA methylation patterns
Oct 2015 | Fertility Sterility
Timothy G. Jenkins, Kenneth I. Aston, Tyson D. Meyer, James M. Hotaling, Monis B. Shamsi, Erica B. Johnstone, Kyley J. Cox, Joseph B. Stanford, Christina A. Porucznik, Douglas T. Carrell
To evaluate the relationship between epigenetic patterns in sperm and fecundity. Twenty-seven semen samples from couples who conceived within 2 months of attempting a pregnancy and 29 semen samples from couples unable to achieve a pregnancy within 12 months. Genomewide assessment of differential sperm DNA methylation and standard semen analysis. <!--more-->We analyzed DNA methylation alterations associated with fecundity in 124 semen samples, and identified regions of interest in 27 semen samples from couples who conceived within 2 months of attempting a pregnancy and a total of 29 semen samples from couples who were unable to achieve a pregnancy within 12 months. No differences in sperm count, sperm morphology, or semen volume were observed between the patients achieving a pregnancy within 2 months of study time and those not obtaining a pregnancy within 12 months. However, using data from the human methylation 450k array analysis we did identify two genomic regions with statistically significantly decreased (false discovery rate <0.01) methylation and three genomic regions with statistically significantly increased methylation in the failure-to-conceive group. The only two sites where decreased methylation was associated with reduced fecundity are at closely related genes known to be expressed in sperm, HSPA1L and HSPA1B. Our data suggest that there are genomic loci where DNA methylation alterations are associated with decreased fecundity. We have thus identified candidate loci for future study to verify these results and investigate the causative or contributory relationship between altered sperm methylation and decreased fecundity.
X chromosome-linked CNVs in male infertility: discovery of overall duplication load and recurrent, patient-specific gains with potential clinical relevance
Jun 2014 | PLoS One
Chiara Chianese, Adam C. Gunning, Claudia Giachini, Fabrice Daguin, Giancarlo Balercia, Elisabet Ars, Deborah Lo Giacco, Eduard Ruiz-Castañé, Gianni Forti, Csilla Krausz
Spermatogenesis is a highly complex process involving several thousand genes, only a minority of which have been studied in infertile men. In a previous study, we identified a number of Copy Number Variants (CNVs) by high-resolution array-Comparative Genomic Hybridization (a-CGH) analysis of the X chromosome, including 16 patient-specific X chromosome-linked gains. Of these, five gains (DUP1A, DUP5, DUP20, DUP26 and DUP40) were selected for further analysis to evaluate their clinical significance. <!--more-->The copy number state of the five selected loci was analyzed by quantitative-PCR on a total of 276 idiopathic infertile patients and 327 controls in a conventional case-control setting (199 subjects belonged to the previous a-CGH study). For one interesting locus (intersecting DUP1A) additional 338 subjects were analyzed. All gains were confirmed as patient-specific and the difference in duplication load between patients and controls is significant (p = 1.65×10−4). Two of the CNVs are private variants, whereas 3 are found recurrently in patients and none of the controls. These CNVs include, or are in close proximity to, genes with testis-specific expression. DUP1A, mapping to the PAR1, is found at the highest frequency (1.4%) that was significantly different from controls (0%) (p = 0.047 after Bonferroni correction). Two mechanisms are proposed by which DUP1A may cause spermatogenic failure: i) by affecting the correct regulation of a gene with potential role in spermatogenesis; ii) by disturbing recombination between PAR1 regions during meiosis. This study allowed the identification of novel spermatogenesis candidate genes linked to the 5 CNVs and the discovery of the first recurrent, X-linked gain with potential clinical relevance.