Regulation of X-chromosome inactivation and imprinting by non-coding elements

非编码元件对 X 染色体失活和印记的调节

• 批准号: 10659211
• 负责人: JEANNIE T LEE
• 金额: $ 47.55万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-01-01 至 2026-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10659211
• 关键词: 3-Dimensional; Address; Affect; Alleles; Atherosclerosis; Biological Models; Biology; Cell model; Cells; Chromatin Loop; Chromosome Pairing; Complex; Data; Daughter; Development; Disease; Elements; Embryo; Enhancers; Ensure; Epigenetic Process; Funding; Future; Gene Silencing; Genes; Germ Cells; Germ Lines; Grant; Health; Human Development; Inherited; Knockout Mice; Learning; Link; Malignant Neoplasms; Measures; Meiosis; Modeling; Molecular; Mus; Paint; Pathway interactions; Placenta; Play; Postdoctoral Fellow; Process; Proteins; Pseudoautosomal Region; RNA; RNA Degradation; Regulation; Repression; Research; Role; Series; Sex Chromosomes; Site; Technology; Titrations; Training; Transgenic Organisms; United States National Institutes of Health; Untranslated RNA; Up-Regulation; Visit; Work; X Chromosome; X Inactivation; autosome; career; cohesin; decapping enzyme; epigenetic regulation; epigenomics; gene repression; genome-wide; imprint; in vivo; mRNA decapping; male; neuronal cell body; permissiveness; promoter; recruit; release factor; stem cell model; trophoblast stem cell

PROJECT SUMMARY Interactions between long noncoding RNAs and epigenetic complexes are now increasingly recognized as important regulators of developmental decisions. A classic example is X-chromosome inactivation (XCI), an epigenetic process by which one X-chromosome becomes inactivated in the early embryo. XCI can take place randomly or in an imprinted manner on the paternal X. In the mouse, random XCI is observed in the embryo proper (soma), and imprinted XCI in the placenta. Both require the ‘X-inactivation center’ (Xic), an X-linked region that harbors several essential noncoding genes. A key gene is Xist, which produces a noncoding RNA that ‘paints’ the X-chromosome and recruits silencing factors in cis. Our work has shown that, during random XCI, Xist is regulated both positively and negatively by Xic factors, with Jpx in the positive pathway and Tsix/Xite in the negative pathway. We have also shown that homologous X- chromosome pairing coordinates which X chromosome will be inactivated. In this funding cycle, we have further advanced understanding of the Xic’s role in X-chromosome counting, allelic choice, and imprinting. For the counting mechanism, Jpx RNA — an Xist activator — serves as an X-linked “numerator” by titrating the autosomal “denominator”, CTCF. This titration accounts for the X-to-autosome (X:A) ratio and creates a permissive state for Xist induction. We also learned that X-X pairing requires a new long noncoding RNA called “PAR-TERRA” produced from the X-linked pseudoautosomal region (PAR). Interestingly, all pairing interactions take place within a “tetrad” of two Xic’s and two PAR’s. X-X pairing is then resolved by mRNA decapping enzyme, DCP1A. For imprinted XCI, we have generated an ex vivo cellular model to study XP imprinting. We have demonstrated that a 200-kb Xic region is sufficient to direct Xist imprinting and that Xist imprinting requires an unpaired state in the male germ line that is akin to meiotic sex chromosome inactivation (MSCI). Our research has generated new opportunities and many additional mechanistic questions. In the next funding cycle, we aim to (i) investigate mechanisms underlying X-X pairing and breaking of X-chromosome symmetry, (ii) determine how Jpx-CTCF titration regulates the initiation of XCI, and (iii) elucidate the mechanisms of imprinted XCI. The proposed work will require five years to complete and is expected to train three postdoctoral fellows for academic careers in the fields of epigenetics and RNA biology.

项目摘要 现在，长期非编码RNA和表观遗传复合物之间的相互作用越来越多地被认为是 发展决策的重要监管者。一个经典的例子是X染色体灭活（XCI），一个 一个X染色体在早期胚胎中灭活的表观遗传过程。 XCI可以接受 在父亲X上随机或以印迹的方式放置。在小鼠中，在小鼠中观察到随机XCI 适当的胚胎（soma）和plapeta中的XCI。两者都需要“ X灭活中心”（XIC） X连锁区域，该区域具有几个必需的非编码基因。一个关键基因是Xist，它产生一个 非编码RNA“绘制” X染色体并募集顺式沉默因子的RNA。我们的工作表明 在随机XCI期间，Xist受到XIC因素的正面和负面调节，JPX在 负途径中的正途径和TSIX/XITE。我们还表明，同源x- X染色体的染色体配对坐标将被灭活。在这个资金周期中，我们有 对XIC在X染色体计数，等位基因选择和印迹中的作用的进一步深入了解。 对于计数机制，JPX RNA（XIST激活器）通过滴定用作X连锁的“分子” 常染色体“ Denotor”，CTCF。该滴定解释了X-to-autosome体（x：a）比率，并创建一个 XIST诱导的允许状态。我们还了解到X-X配对需要一个新的长不编码RNA 从X连锁的假阳性区域（PAR）产生的“ Par-terra”。有趣的是，所有配对 互动发生在两个XIC和两个PAR的“四核”中。然后通过mRNA解决X-X配对 decapping酶，dcp1a。对于印迹XCI，我们已经生成了一个离体细胞模型来研究XP 烙印。我们已经证明，200 kb的XIC区域足以指导XIST印迹，并且该XIST 烙印需要在男性细菌系中的未配对状态，类似于减数分裂性染色体 失活（MSCI）。我们的研究产生了新的机会和许多其他机械 问题。在下一个资金周期中，我们的目标是（i）调查X-X配对和 X染色体对称性的破坏（II）确定JPX-CTCF滴定如何调节XCI的主动性， （iii）阐明印迹XCI的机制。拟议的工作将需要五年才能完成 并有望在表观遗传学和RNA领域培训三名博士后研究员 生物学。