Epigenetic regulation of X chromosomes during female mouse embryogenesis

雌性小鼠胚胎发生过程中 X 染色体的表观遗传调控

• 批准号: 9791350
• 负责人: INGOLF M BACH
• 金额: $ 37.69万
• 依托单位: UNIV OF MASSACHUSETTS MED SCH WORCESTER
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-24 至 2022-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9791350
• 关键词: Adult; Affect; Applications Grants; Cell Maintenance; Cell Nucleus; Cells; Confusion; Data; Defect; Development; Dosage Compensation (Genetics); Down-Regulation; Embryo; Embryonic Development; Epiblast; Epigenetic Process; Exclusion; Failure; Female; Gene Silencing; Genes; Genetic; Genetic Transcription; Grant; Implant; In Vitro; Investigation; Knock-in Mouse; Lead; Link; Maintenance; Mammals; Mediator of activation protein; Modeling; Molecular; Mus; Nuclear; Paint; Pathway interactions; Pattern; Probability; Process; Publishing; RNA; RNA Binding; RNA Splicing; Regulation; Regulatory Pathway; Reproduction; Research; Role; Sex Chromosomes; Signal Pathway; Stem cells; System; Testing; Tissues; Untranslated RNA; Work; X Chromosome; X Inactivation; base; chromatin modification; design; embryo tissue; epigenetic regulation; failure Implantation; implantation; imprint; in vivo; mouse development; mutant; natural Blastocyst Implantation; novel; nucleocytoplasmic transport; preimplantation; self-renewal; sex; stem cell biology; stem cell fate; stem cell niche; trophoblast; ubiquitin ligase; ubiquitin-protein ligase

Abstract The development and reproduction of female mammals is dependent on dosage compensation from sex chromosomes. Indeed, female mammals silence one of their two X chromosomes (X) in a process called X inactivation (XCI), a paradigm for epigenetic gene silencing. In mice, XCI occurs early during female embryogenesis in two waves. In embryos at the 2-4 cell stage, an early imprinted form of XCI (iXCI) silences exclusively the paternal X (Xp). Around implantation, however, female epiblast cells that give rise to somatic embryonic tissues undergo a major epigenetic switch: These cells reactivate the silenced Xp (XCR) and undergo another, random form of XCI (rXCI), silencing the paternal or maternal X with equal probability. Thus, tissues in the adult female mouse generally display a random XCI pattern. Xist RNA is crucial for X- silencing both during iXCI and rXCI and paints the inactive X from which it is expressed as a cloud, triggering downstream repressive chromatin modifications and X-silencing. We discovered that in mice the X-linked ubiquitin ligase RLIM is crucial for Xist functioning and maintenance of Xist clouds during iXCI and that lack of Rlim disrupts embryo implantation due to trophoblast failure. However, Rlim is dispensable for rXCI in epiblast cells of peri- and post- implantation embryos. Thus, the reasons of how X dosage compensation defects inhibit trophoblast functions as well as the pathways that regulate Xist during rXCI are unknown, and regulatory pathways triggering the developmental switch from iXCI to rXCI in epiblasts remain enigmatic. The research proposed in this grant is based on our published and preliminary work and will use mouse genetics combined with a newly generated female ESC model that permits investigations of XCI in the absence of Rlim. In particular, we will explore the effects of iXCI failure on trophoblast stem cell fates (Aim 1), examine novel mechanisms of rXCI regulation in female ESCs (Aim 2) and unravel in vivo mechanisms of XCR in female peri-implantation embryos (Aim 3). The proposed research will identify novel mechanisms of trophoblast stem cell maintenance, underlying regulation of Xist both during rXCI and iXCI and illuminate mechanisms underlying XCR. The combined results will allow designing the first comprehensive model of a iXCI/XCR/rXCI epigenetic switch that occurs in epiblast cells of developing female mice. Expected results will have transformative impact in the fields of early mouse development, stem cell biology, female reproduction and sex-specific epigenetic regulation.

抽象的 女性哺乳动物的发展和繁殖取决于剂量补偿 来自性别染色体。实际上，女性哺乳动物沉默的两个X染色体之一（x） 在称为X灭活（XCI）的过程中，是表观遗传基因沉默的范式。在小鼠中，XCI 发生在两波中的女性胚胎发生期间。在2-4个细胞阶段的胚胎中 XCI（IXCI）沉默的早期印迹形式仅是父亲X（XP）。在植入周围， 但是，产生体细胞胚胎组织的雌性纤维细胞会经历主要 表观遗传开关：这些细胞重新激活沉默的XP（XCR）并进行另一个随机的 XCI（RXCI）的形式，以相等的概率使父亲或母亲X沉默。因此，组织 成年雌鼠通常显示随机的XCI模式。 Xist RNA对于X-至关重要 在IXCI和RXCI期间沉默，并绘制其表达为无效的X 云，触发下游抑制性染色质修饰和X分解。我们 发现在小鼠中，X连锁的泛素连接酶rlim对于XIST功能和 维持IXCI期间的Xist云，缺乏RLIM破坏胚胎植入 滋养细胞失败。但是，RLIM在周围和后的e-和 植入胚胎。因此，X剂量补偿缺陷的原因抑制 滋养细胞的功能以及调节RXCI期间XIST的途径尚不清楚，并且 触发从IXCI到RXCI的发育切换的监管途径仍然存在 神秘。 该赠款中提出的研究是基于我们发表的初步工作， 将使用鼠标遗传学与新生成的女性ESC模型相结合，该模型允许 在没有RLIM的情况下对XCI进行调查。特别是，我们将探索IXCI的影响 滋养细胞干细胞命运的失败（AIM 1），检查RXCI调节的新机制 雌性ESC（AIM 2）和XCR雌性植入术的体内机制 胚胎（目标3）。 拟议的研究将确定滋养细胞干细胞的新机制 维护，在RXCI和IXCI期间对XIST的基础调节并照明 XCR的基础机制。结合结果将允许设计第一个综合 IXCI/XCR/RXCI表观遗传开关的模型，该开关发生在发育中的雌性的epiblast细胞中 老鼠。预期结果将对早期小鼠发育领域产生变革性影响， 干细胞生物学，女性繁殖和性别特异性表观遗传调节。