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.

项目概要 长非编码 RNA 和表观遗传复合物之间的相互作用现在越来越被认为是 一个典型的例子是 X 染色体失活 (XCI)，它是发育决定的重要调节因子。 XCI 可以通过表观遗传过程使一条 X 染色体在早期胚胎中失活。 放置或以印记方式随机地在父系 X 上。在小鼠中，在父系 X 中观察到随机 XCI 胚胎本身（体体）和胎盘中的印记 XCI 都需要“X 失活中心”（Xic）。 X连锁区域包含几个必需的非编码基因，其中一个关键基因是Xist，它产生一个 我们的工作表明，“绘制”X 染色体并招募顺式沉默因子的非编码 RNA。 在随机 XCI 期间，Xist 受到 Xic 因素的正向和负向调节，其中 Jpx 在 正途径和负途径中的 Tsix/Xite 我们还证明了同源的 X-。 染色体配对协调哪条 X 染色体将被失活 在这个资助周期中，我们有。 进一步加深了对 Xic 在 X 染色体计数、等位基因选择和印记中作用的理解。 对于计数机制，Jpx RNA（一种 Xist 激活剂）通过滴定充当 X 连锁“分子” 常染色体“分母”CTCF 该滴定考虑了 X 与常染色体 (X:A) 的比率并创建了一个 我们还了解到 X-X 配对需要新的长非编码 RNA。 由 X 连锁伪常染色体区域 (PAR) 产生的称为“PAR-TERRA”的基因表明，所有配对 相互作用发生在两个 Xic 和两个 PAR 的“四分体”内，然后由 mRNA 解析。 对于印迹 XCI，我们生成了一个离体细胞模型来研究 XP。 我们已经证明 200-kb Xic 区域足以指导 Xist 印记，并且 Xist 印记需要雄性种系中的未配对状态，类似于减数分裂性染色体 我们的研究产生了新的机会和许多额外的机制。 在下一个资助周期中，我们的目标是 (i) 研究 X-X 配对和潜在的机制。 X 染色体对称性的破坏，(ii) 确定 Jpx-CTCF 滴定如何调节 XCI 的启动， (iii) 阐明印记 XCI 的机制 建议的工作需要五年时间才能完成。 预计将培养三名表观遗传学和RNA领域学术职业博士后 生物学。