Epigenetic Mechanisms of X-chromosome Inactivation

X染色体失活的表观遗传机制

• 批准号: 7924264
• 负责人: SUNDEEP KALANTRY
• 金额: $ 24.9万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2012-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7924264
• 关键词: Address; Antibodies; Biochemical; Biological Assay; Biological Models; Bypass; Cell Line; Cell division; Cells; Chromosomes; Complex; DNA; DNA Sequence; Developmental Process; Disease; Disease Progression; Dosage Compensation (Genetics); Embryo; Embryonic Development; Endoderm; Epigenetic Process; Female; Figs - dietary; Functional RNA; Gene Expression; Gene Expression Regulation; Gene Silencing; Genes; Genetic Transcription; Histones; Human; Individual; Inherited; Malignant Neoplasms; Mammals; Mediating; Memory; Methylation; Methyltransferase; Molecular Profiling; Mus; Pattern; Polycomb; Process; Proteins; RNA; Research; Reverse Transcriptase Polymerase Chain Reaction; Small Interfering RNA; Staging; Stem cells; X Chromosome; X Inactivation; blastocyst; histone modification; human disease; imprint; insight; instrument; knock-down; novel; null mutation; stem cell biology; trophoblast

Cells retain tlieir identity in part by inheriting gene expression profiles of their predecessors. Patterns of transcription that survive cell division are thought to be established and maintained partly through covalent modifications of histones and DNA, and do not involve changes in the DNA sequence itself. Emerging evidence increasingly implicates this epigenetic mode of inheritance in a myriad of developmental processes as well as a cause of or a significant contributor to human disease. My research strives to further our understanding of epigenetic mechanisms through the study of X-chromosome Inactivation (XCI). XCI is an instrument of dosage compensation in mammals that results in the transraiptlonal silencing of genes on one of the two X-chromosomes in eariy female embryos. Once enacted in individual cells, XCI is stably transmitted such that all descendant ceils maintain silencing of that X-chromosome. Since an entire chromosome is inactivated and tfierefore easily detected, XCI is a model system to investigate transcriptional memory mechanisms. Importantly, the memory mechanisms that operate during XCI also apply broadly to gene regulation and are being found to be important in cell fate decisions during embryogenesis and in stem cell biology as well as during disease progression. We have recently identified a novel protein enriched on the inactive X-chromosome (Xi), This protein is predicted to be a novel putative methyltransferase. The Xi is a target of two known MTases (Ezh2 and Pr- Set7), which operate on the Xi to propagate transcriptional memory by catalyzing the methylation of histones either on their own or In a complex with other proteins. We will therefore deteimine if the novel protein mediates cellular memory through histone methylation, using established biochemical assays to detect histone methylation on core histones as well as on nudeosome substrates. We also aim to Identify proteins that with which It interacts. We will also generate mice bearing a conditional-null mutation in the gene to analyze its requirement in XCI.

细胞通过继承其前辈的基因表达谱来部分地保持其身份。在细胞分裂中存活的转录模式被认为部分通过组蛋白和DNA的共价修饰来建立和维持，并且不涉及DNA序列本身的变化。越来越多的证据表明，这种表观遗传模式在无数的发展过程中，以及人类疾病的原因或重大贡献。我的研究致力于通过X染色体失活（XCI）的研究进一步了解表观遗传机制。XCI是哺乳动物中的剂量补偿工具，其导致早期雌性胚胎中两条X染色体之一上的基因的跨克隆沉默。一旦在个体细胞中发生，XCI就被稳定地传递，使得所有后代细胞维持该X染色体的沉默。由于整个染色体是失活的，因此很容易检测到，XCI是研究转录记忆机制的模型系统。重要的是，在XCI期间运作的记忆机制也广泛应用于基因调控，并且被发现在XCI期间的细胞命运决定中很重要。 胚胎发生和干细胞生物学以及疾病进展期间。 我们最近在失活X染色体上发现了一种新的蛋白质，该蛋白质被预测为一种新的甲基转移酶。X1是两种已知MTase（Ezh 2和Pr-Set 7）的靶标，其对X1起作用以通过催化组蛋白自身或与其他蛋白质复合的甲基化来传播转录记忆。因此，我们将使用已建立的生物化学测定来检测核心组蛋白以及核小体底物上的组蛋白甲基化，以确定新蛋白是否通过组蛋白甲基化介导细胞记忆。我们的目标是确定与它相互作用的蛋白质。我们还将产生基因中携带条件无效突变的小鼠，以分析其在XCI中的需求。