Role of DNA methylation in imprint maintenance in differentiated human cells

DNA甲基化在分化的人类细胞印记维持中的作用

• 批准号: MR/J007773/1
• 负责人: Colum Walsh
• 金额: $ 48.25万
• 依托单位: University of Ulster
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2012
• 资助国家: 英国
• 起止时间: 2012 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FJ007773%2F1
• 关键词: Role; DNA; methylation; imprint; maintenance

SummaryThe phenomenon of genomic imprinting lies at the heart of a significant number of childhood disease syndromes, including disorders such as Beckwith-Weidemann Syndrome (BWS), Prader-Willi Syndrome (PWS) and Transient neonatal diabetes mellitus (TNDM) type I. Each of these syndromes involves a gene which is imprinted, that is to say is normally only active from one of the two chromosomes in the cell, either the one inherited from the father via the sperm, or the one inherited from the mother via the egg, the genes thus being "imprinted" with a memory of which parent they came from. Patients with imprinted disease syndromes have increased risks for further problems such as diabetes (TNDM) or Wilms' tumour (BWS) in later life as well. The mechanism by which one copy of a gene becomes inactivated, while its identical partner in the same cell nucleus remains active, is still under active research. We know that chemical tags added to the DNA, called DNA methylation, are involved in marking the inactive copy of the imprinted gene, but it is not known whether this is sufficient in all cases to turn off the gene, or whether the proteins associated with the DNA, called histones, are more important. While such mechanistic questions can be addressed in experimental animals such as mice, human studies have either used cells from patients, where it is not possible to tell if the changes seen in the DNA methylation or the histones are causative, or have manipulated DNA methylation levels using drugs in cancer cell lines, which are not genetically stable and thus a poor model. We have developed human cell lines which are non-cancerous and genetically stable, with normal imprinting, and then selectively reduced the levels of DNA methylation only. These cells appear to show loss of imprinting of the genes which cause BWS and PWS and most likely all other imprinted regions, but are unaffected at non-imprinted regions. They have altered growth characteristics and appearance, in line with theories that imprinted genes have important roles in regulating growth and nutrition. They thus represent a unique resource for exploring the importance of DNA methylation versus histone status in regulating imprinted genes and by cross-comparing to cells from BWS patients and others, it should be possible to establish which is more likely to be causative. The cells are a potentially valuable tool for determining the side-effects of pharmacological inhibitors of DNA methylation currently being used in the clinic. We can also use the cells to look for previously unrecognised imprinted genes, which may be linked to additional disorders. Additionally we can use the cells to carry out further mechanistic work, including attempting to identify the factors involved in establishing imprints, which would in turn be candidates for causative agents in these diseases.

基因组印记现象是大量儿童疾病综合征的核心，包括诸如Beckwith-Weidemann综合征（BWS）、Prader-Willi综合征（PWS）和暂时性新生儿糖尿病（TNDM）I型等疾病。这些综合征中的每一个都涉及一个基因，该基因是印记的，也就是说，通常只在细胞中的两条染色体中的一条上活跃，要么是通过精子从父亲继承的染色体，要么是通过卵子从母亲继承的染色体，因此，基因被“印记”了它们来自哪个父母的记忆。患有印记疾病综合征的患者在以后的生活中也会增加进一步问题的风险，如糖尿病（TNDM）或肾母细胞瘤（BWS）。一个基因的一个拷贝变得失活，而同一细胞核中相同的伙伴仍然活跃，这一机制仍在积极研究中。我们知道添加到DNA上的化学标签，称为DNA甲基化，参与标记印记基因的非活性拷贝，但不知道这是否在所有情况下都足以关闭基因，或者是否与DNA相关的蛋白质，称为组蛋白，更重要。虽然这些机制问题可以在实验动物（如小鼠）中解决，但人类研究要么使用患者的细胞，其中不可能判断DNA甲基化或组蛋白中观察到的变化是否是病因，要么使用药物在癌细胞系中操纵DNA甲基化水平，这是遗传不稳定的，因此是一个很差的模型。我们已经开发出非癌性和遗传稳定的人类细胞系，具有正常的印记，然后选择性地降低DNA甲基化水平。这些细胞似乎显示出导致BWS和PWS的基因印记的丢失，并且很可能是所有其他印记区域，但在非印记区域不受影响。它们改变了生长特征和外观，这与印记基因在调节生长和营养方面发挥重要作用的理论一致。因此，它们代表了一种独特的资源，用于探索DNA甲基化与组蛋白状态在调节印记基因中的重要性，并通过与BWS患者和其他人的细胞进行交叉比较，应该可以确定哪一种更有可能是病因。这些细胞是一种潜在的有价值的工具，用于确定目前临床上使用的DNA甲基化药理学抑制剂的副作用。我们还可以利用这些细胞来寻找以前未被识别的印记基因，这些基因可能与其他疾病有关。此外，我们还可以利用这些细胞进行进一步的机制研究，包括试图确定参与建立印记的因素，这些因素反过来又会成为这些疾病的致病因子。

项目成果

5-Hydroxymethylation marks a class of neuronal gene regulated by intragenic methylcytosine levels

• DOI: 10.1016/j.ygeno.2014.08.013
• 发表时间: 2014-11-01
• 期刊: GENOMICS
• 影响因子: 4.4
• 作者: Irwin, Rachelle E.;Thakur, Avinash;Walsh, Colum P.
• 通讯作者: Walsh, Colum P.

Exposure of bovine oocytes and embryos to elevated non-esterified fatty acid concentrations: integration of epigenetic and transcriptomic signatures in resultant blastocysts.

• DOI: 10.1186/s12864-016-3366-y
• 发表时间: 2016-12-08
• 期刊: BMC genomics
• 影响因子: 4.4
• 作者: Desmet KL;Van Hoeck V;Gagné D;Fournier E;Thakur A;O'Doherty AM;Walsh CP;Sirard MA;Bols PE;Leroy JL
• 通讯作者: Leroy JL