Epigenetic signatures in the ageing male germ cell.

衰老男性生殖细胞的表观遗传特征。

• 批准号: 288470100
• 负责人: Professor Dr. Jörg Gromoll
• 金额: --
• 依托单位: Abteilung für Klinische und Operative Andrologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/288470100?language=en
• 关键词: Epigenetic; signatures; ageing; male; germ

In western countries there is a strong trend for delaying parenthood. While the consequences of postponed maternity, such as an increased risk for chromosomal anomalies, are well known, our knowledge on male reproductive ageing (i.e. ageing affecting the male germ cells) is scant. There is strong evidence for a significant effect of paternal age on male germ cell function e.g. increase in the prevalence of certain genetic disorders in the offspring. However, we do not know to which extent ageing affects epigenetic signatures, especially DNA methylation, and whether infertile men are at an additive risk for these epimutations. We hypothesize that reproductive ageing affects the epigenetic signatures of male germ cells: spermatogonial stem cells (SSCs) age differently when compared to somatic cells and spermatozoa, deriving from these SSCs, reflect this different ageing process.We will address whether noticeable epigenetic, genetic and cellular changes occur in the germ line of healthy men during ageing and if these dynamics are altered in infertile men. A fully-characterized collection of blood and semen samples from a healthy study men cohort (18-75 years) will constitute a vital tool for studying the effects of ageing. Telomere length (TL) will be measured in blood and sperm DNA of age-matched healthy and infertile men to determine if sperm TL changes with age and to which extent infertility affects ageing. Biological/epigenetic age can be determined by measuring the DNA methylation of distinct CpG sites in the genome. Therefore blood, sperm and spermatogonial DNA from our healthy age groups will be investigated to determine whether the germ line ages in a similar or distinct way from somatic cells. By studying the sperm epigenetic heterogeneity we could deduce an age-dependent change in the clonal origin of sperm and in the cellular SSC composition.At the functional level we will evaluate whether the SSC population itself changes with age. A histomorphometric analysis on fixed testicular tissues delineates the extent to which their stem cell features are affected by age. The clonal expansion of SSC will be studied by immunohistochemistry with stem cell specific and DNA methylation markers. Native SSCs will be isolated from testicular biopsies and characterized by RNA profiling and immunostaining .Using the enriched SSCs we head to whether age-dependent epigenetic changes are restricted to only a few genes or affect multiple regions in the genome. For this we will perform a whole-methylome sequencing in spermatogonial DNA, which will allow us to identify putative candidate loci for age-related methylation changes in the male germ line. This project will greatly increase our knowledge of reproductive ageing in men, and help to identify the risks associated with delayed paternity.

在西方国家有一种推迟生育的强烈趋势。 虽然推迟生育的后果，如染色体异常风险增加，是众所周知的，但我们对男性生殖老化（即影响男性生殖细胞的老化）的了解却很少。 有强有力的证据表明，父亲的年龄对男性生殖细胞功能有显著影响，例如，后代中某些遗传疾病的患病率增加。然而，我们不知道衰老在多大程度上影响表观遗传特征，特别是DNA甲基化，以及不育男性是否存在这些表观突变的附加风险。我们假设生殖衰老影响男性生殖细胞的表观遗传特征：精原干细胞（SSCs）的年龄与体细胞和精子相比不同，来自这些SSCs的精子反映了这种不同的衰老过程，我们将讨论健康男性生殖系在衰老过程中是否发生明显的表观遗传，遗传和细胞变化，以及这些动态在不育男性中是否发生改变。来自健康研究男性队列（18-75岁）的血液和精液样本的完全特征化收集将构成研究衰老影响的重要工具。将测量年龄匹配的健康和不育男性的血液和精子DNA中的端粒长度（TL），以确定精子TL是否随年龄变化以及不育对衰老的影响程度。生物学/表观遗传年龄可以通过测量基因组中不同CpG位点的DNA甲基化来确定。因此，将对我们健康年龄组的血液、精子和精原DNA进行研究，以确定种系衰老是否与体细胞相似或不同。通过研究精子表观遗传异质性，我们可以推断出精子克隆起源和细胞SSC组成的年龄依赖性变化。在功能水平上，我们将评估SSC群体本身是否随年龄变化。固定睾丸组织的组织形态计量学分析描绘了其干细胞特征受年龄影响的程度。SSC的克隆扩增将通过具有干细胞特异性和DNA甲基化标志物的免疫组织化学来研究。天然的精原干细胞将从睾丸活检中分离出来，并通过RNA分析和免疫染色进行表征。使用富集的精原干细胞，我们将研究年龄依赖性表观遗传变化是否仅限于少数基因或影响基因组中的多个区域。为此，我们将在精原细胞DNA中进行全甲基化组测序，这将使我们能够确定男性生殖系中与年龄相关的甲基化变化的假定候选位点。该项目将大大增加我们对男性生殖年龄的认识，并有助于确定与推迟生育有关的风险。