Mechanism Underlying the Transduction of Epimutations from the Soma to the Male Germline

项目摘要 大多数关于表观遗传的研究都集中在鉴定携带精子的因素上。 表观遗传记忆以及它们如何作用于胚胎的表观基因组/基因组， 表观遗传记忆可以被回忆起来，并在后代中表现为特定的表型。不过有一 一个根本的问题仍然没有答案：鉴于暴露的影响，无论是环境还是 饮食，可能最初表现为直接暴露的体细胞中的表观遗传变化（例如， 胰岛细胞、脂肪细胞、肝细胞等），表型特异性表型突变是如何 体细胞转化为精子使用高度可重复的小鼠模型， 高脂饮食（HFD）引起的代谢紊乱的代际表观遗传，我们在这里 提出了一系列实验来解决这个关键问题。我们的中心假设是HFD- 体细胞中诱导的表突变可导致产生特异性sncRNA， 包封在细胞外囊泡（EV）中，或作为移动的RNA存在，其充当细胞外囊泡（EV）的载体。 表观遗传记忆一旦被精子内化，通过1）睾丸内机制 (i.e.,支持细胞HDF特异性表观遗传信息传递到所有发育中的雄性生殖细胞， 在睾丸中精子发生期间直接作用于精子），或2）睾丸后途径（即， HFD特异性表观遗传信息从男性生殖道上皮细胞传递到 精子），或3）两者的组合。为了验证我们的假设，我们建议确定何时和 当雄性生殖细胞获得传递HDF诱导的代谢紊乱表型（Aim 1）的能力时， 研究睾丸内途径如何促进HFD特异性精子表观基因组（Aim 2）， 研究睾丸后途径如何影响HFD特异性精子表观基因组（Aim 3）。数据 这将有助于填补我们对潜在分子机制的理解的知识空白。 一般来说，父系获得的特征的代际表观遗传。

Project Summary Most of the studies on epigenetic inheritance focus on the identification of sperm-borne factors that carry the epigenetic memory and how they act on the epigenome/genome of the embryos so that the specific epigenetic memory can be recalled and manifested as a specific phenotype in offspring. However, one fundamental question remains unanswered: given that the effects of exposures, either environmental or dietary, are presumably initially manifested as epigenetic changes in directly exposed somatic cells (e.g. pancreatic islet cells, adipocytes, hepatocytes, etc.), how do the phenotype-specific epimutations in somatic cells get transduced into spermatozoa? Using a highly reproducible mouse model for intergenerational epigenetic inheritance of a high fat diet (HFD)-induced metabolic disorders, we here propose a series of experiments to tackle this critical question. Our central hypothesis is that HFD- induced epimutations in somatic cells can lead to production of specific sncRNAs that are either encapsulated in extracellular vesicles (EVs), or present as mobile RNAs, which act as the carrier of epigenetic memory once internalized by spermatozoa through either 1) the intra-testicular mechanism (i.e., Sertoli cell HDF-specific epigenetic information transmitted to all developing male germ cells or directly to spermatozoa during spermatogenesis in the testis), or 2) the post-testicular pathway (i.e., HFD-specific epigenetic information transmitted from male reproductive tract epithelial cells to spermatozoa), or 3) a combination of both. To test our hypothesis, we propose to identify when and where male germ cells gain the ability to transmit the HDF-induced metabolic disorder phenotype (Aim1), to study how the intra-testicular pathway contributes to the HFD-specific sperm epigenome (Aim2), to study how the post-testicular pathway influences HFD-specific sperm epigenome (Aim3). Data to be obtained will help fill the knowledge gap in our understanding of the molecular mechanisms underlying the intergenerational epigenetic inheritance of paternally acquired traits in general.