X-chromosome Inactivation Catalyzed by Genes That Escape X-inactivation

由逃避 X 失活的基因催化的 X 染色体失活

• 批准号: 9753029
• 负责人: SUNDEEP KALANTRY
• 金额: $ 41.18万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-08 至 2021-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9753029
• 关键词: 3-Dimensional; Address; Alleles; Biochemical; Cell Cycle; Cell division; Cell physiology; Cells; ChIP-seq; Chromatin; Chromosomes, Human, 6-12 and X; Consensus; Custom; DNA Binding; Data; Development; Developmental Process; Dimensions; Disease; Disease Progression; Dissection; Dose; Embryo; Embryonic Development; Epiblast; Epigenetic Process; Event; Female; Future; Gene Dosage; Gene Expression Profile; Gene Silencing; Genes; Genetic Transcription; Goals; Heritability; Histones; Hybrids; Immunoprecipitation; Length; Link; Mammals; Mitotic; Modeling; Molecular Conformation; Mus; Mutant Strains Mice; Nucleoplasm; Pattern; Publishing; RNA; Role; Series; Stem cells; System; Techniques; Testing; Therapeutic; Transcriptional Regulation; Untranslated RNA; Work; X Chromosome; X Inactivation; base; chromosome conformation capture; embryonic stem cell; epigenetic regulation; epigenome; experimental study; human disease; improved; insight; male; novel; overexpression; placental mammal; transcriptome sequencing

Abstract Epigenetic transcriptional regulation is required for a myriad of developmental processes as well as being a significant contributor to human diseases. X-chromosome inactivation provides an experimentally tractable system for the dissection of epigenetic inheritance. X-inactivation results in the mitotically-heritable transcriptional inactivation of one X-chromosome in female mammals, thereby equalizing X-linked gene dosage between males and females. X-inactivation requires the Xist long non-coding RNA that is expressed only from the inactive X-chromosome. Current models posit that Xist RNA induction and coating of the X- chromosome in cis triggers a series of epigenetic events that culminates in X-inactivation. Notably, how Xist is selectively induced in females and not at all in males and how it triggers silencing are still unresolved questions. The objective of this proposal is to address how Xist expression and X-linked gene silencing are triggered during X-inactivation. Our central hypothesis, based on our published work and preliminary data, is that genes that escape X-inactivation function as dose-sensitive factors that induce Xist and, separately, potentiate X-linked gene silencing selectively in females. X-inactivation escapees are expressed from both X- chromosomes in XX females, including from the otherwise inactivated X-chromosome; hence, their expression is higher in females compared to XY males. We developed and employed a custom allele-specific RNA- sequencing pipeline to compile a list of the escape genes in mouse epiblast stem cells, which harbor an inactive-X. We then prioritized validated escapees that are predicted to be evolutionarily conserved and which function as transcriptional/chromatin regulators for a role in inducing X-inactivation. In this proposal, we systematically test the dose-dependent and biochemical activities of two of these escape genes in triggering Xist expression and X-linked gene silencing using unbiased and integrated high-throughput approaches. The results are expected to inform how genes along the length of the X-chromosome are silenced and why females undergo X-inactivation and males do not. The epigenetic factors and mechanisms that execute X-inactivation are known to overlap with those that regulate embryonic development and disease progression. Thus, understanding the cascade of epigenetic events that characterizes X-inactivation offers a window into identifying the common factors and mechanisms that establish epigenetic expression patterns broadly.

抽象的 众多的发育过程需要表观遗传转录调节，并且是 人类疾病的重要贡献者。 X染色体灭活提供了实验性的障碍 解剖表观遗传遗传的系统。 X灭活导致有丝分裂的可容纳 雌性哺乳动物中一个X染色体的转录失活，从而使X连锁基因均衡 男性和女性之间的剂量。 X灭活需要表达的Xist长的非编码RNA 仅来自非活性X染色体。当前模型认为x-的Xist RNA诱导和涂层 顺式中的染色体会触发一系列最终在X灭活中的表观遗传事件。值得注意的是，XIST如何 在女性中有选择地诱导的，而在男性中根本没有诱导，它如何触发沉默仍未解决 问题。该提议的目的是解决XIST表达和X连锁基因沉默如何 在X灭活过程中触发。根据我们已发表的工作和初步数据，我们的中心假设是 逃避X灭活的基因作为剂量敏感因素，诱导Xist，并分别诱导XIST 在女性中有选择地增强X连锁基因沉默。 X灭活逃脱均来自两个X- XX女性中的染色体，包括来自其他灭活的X染色体；因此，他们的表情 与XY男性相比，女性的女性更高。我们开发并采用了定制等位基因特异性的RNA- 测序管道以编译小鼠epepiblast干细胞中的逃生基因列表，该细胞带有 无效-x。然后，我们优先考虑经过验证的逃生者，预计将在进化上保守，哪些 作为转录/染色质调节剂的功能，在诱导X灭活中发挥作用。在这个建议中，我们 系统地测试其中两个逃生基因的剂量依赖性和生化活性 XIST表达和X连锁基因沉默，采用无偏和集成的高通量方法。这 结果有望告知沿X染色体长度的基因如何沉默以及女性为什么 进行X灭活，而男性则不会。执行X灭活的表观遗传因素和机制 已知会与调节胚胎发育和疾病进展的人重叠。因此， 了解特征X灭活的表观遗传事件的级联为进入 确定广泛建立表观遗传表达模式的常见因素和机制。