DNA Replication and Genome-Wide Demethylation in Erythropoiesis

红细胞生成过程中的 DNA 复制和全基因组去甲基化

基本信息

批准号：
8563099
负责人：
Merav Socolovsky
金额：
$ 36.2万
依托单位：
UNIV OF MASSACHUSETTS MED SCH WORCESTER
依托单位国家：
美国
项目类别：
财政年份：
2013
资助国家：
美国
起止时间：
2013-06-07 至 2017-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8563099
关键词：
Aberrant DNA Methylation Acceleration Accounting Anemia Behavior Cell Cycle Cell Differentiation process Cells Characteristics Comb animal structure Cyclin-Dependent Kinase Inhibitor Cytosine DNA DNA Methylation DNA Methyltransferase DNA Modification Methylases DNA biosynthesis Daughter Development Dinucleoside Phosphates Down-Regulation Dysmyelopoietic Syndromes Elements Embryonic Development Enzymes Epigenetic Process Erythroblasts Erythrocytes Erythroid Erythropoiesis Erythropoietin Fetal Liver Funding Gene Expression Generations Genes Genetic Transcription Genome Genomics Goals Hematopoietic Hematopoietic stem cells Knockout Mice Maintenance Mediating Methylation Modeling Modification Pattern Process Proteins Refractory anemias Regulation Replication Origin Research Resistance Role S Phase Science Somatic Cell Syndrome Testing Tetanus Helper Peptide Time Tissues Wild Type Mouse Work base demethylation erythroid differentiation gene induction genome-wide knock-down mammalian genome methyl group neuronal cell body novel overexpression oxidation prevent progenitor programs public health relevance self-renewal

项目摘要

DESCRIPTION (provided by applicant): In the mammalian genome, ~70% of cytosines within 5'-CpG-3' dinucleotides are methylated, an epigenetic modification correlating with transcriptional silencing. Twice in pluripotent early development, DNA methylation is globally erased. It is then re-established and maintained throughout somatic cell differentiation. Until recently, no global methylation changes were thought to occur in normal somatic cells. This long-held dogma was overturned by our discovery that erythroid differentiation is associated with DNA demethylation at nearly all genomic elements. Global demethylation is required for rapid erythroid gene induction. It represents a novel genome-wide epigenetic transformation essential for erythroid maturation, whose mechanism is as yet unknown. We hypothesize that disruption of global erythroid demethylation may underlie syndromes of erythropoietin-resistant anemias. Indeed, genome-wide aberrant DNA methylation was recently found in the refractory anemias classified as myelodysplastic syndromes (MDS), where demethylation therapy is successful. Our long-term goal is to elucidate the mechanism and function of global DNA demethylation in erythropoiesis and the consequences of its dysregulation. During replication, DNA methyltransferase 1 (Dnmt1) methylates nascent DNA, thereby maintaining DNA methylation across cell generations. Erythroid global demethylation is dependent on DNA replication, suggesting impaired Dnmt1 function. Demethylation further requires an accelerated intra-S phase DNA synthesis, a recently-discovered cell cycle behavior at the onset of erythroid differentiation whose mechanism is unknown. Demethylation in erythroblasts is not, however, associated with Dnmt1 loss, and cannot be prevented by Dnmt1 overexpression. Together, these observations suggest the hypothesis that erythroblasts contain mechanisms limiting the methylation capacity of Dnmt1. We propose to test this hypothesis with the following three aims: Aim 1: Determine whether 5mC in erythroid genomic DNA is subject to oxidation by the enzyme Tet2, resulting in replication-dependent, Dnmt1-resistant global demethylation Aim 2: Determine the role of the Cyclin-dependent kinase inhibitor p57KIP2 in S phase acceleration and in erythroid global DNA demethylation. Aim 3: Determine the underlying mechanism of the accelerated intra-S phase DNA synthesis at the onset of erythroid differentiation: is it caused by an increased number of firing replication origins, or by increased rate of replication fork progression. Ask whether this process is regulated by the cyclin-dependent kinase inhibitor p57KIP2. Funding of this work will elucidate how global methylation patterns are regulated, and may provide conceptually new avenues for therapy of erythropoietin-resistant anemias.

描述（由申请人提供）：在哺乳动物的基因组中，在5'-CPG-3'二核苷酸内约有70％的胞嘧啶是甲基化的，一种与转录沉默相关的表观遗传修饰。在多能早期发育中，DNA甲基化两次。然后将其重新建立并保持整个体细胞分化。直到最近，在正常的体细胞中还没有发现全球甲基化变化。我们的发现，这种长期以来的教条被推翻了，几乎所有基因组元素在几乎所有基因组元素上都与DNA脱甲基化有关。快速红系基因诱导需要全球脱甲基化。它代表了整个基因组的新型表观遗传转化对于红斑成熟所必需的，其机制尚不清楚。我们假设全球红细胞脱甲基化的破坏可能是促红细胞生成素贫血的综合症的基础。实际上，最近在被分类为骨髓增生综合征（MDS）的难治性贫血中发现了全基因组异常的DNA甲基化，其中脱甲基疗法成功。我们的长期目标是阐明促红细胞生成中全球DNA脱甲基化的机制和功能及其失调的后果。在复制过程中，DNA甲基转移酶1（DNMT1）甲基化的新生DNA，从而在细胞世代保持DNA甲基化。红细胞全局脱甲基化取决于DNA复制，这表明DNMT1功能受损。脱甲基化进一步需要加速的S期DNA合成，这是一种未知机制的红细胞分化开始时近期发现的细胞周期行为。但是，红细胞中的脱甲基化与DNMT1损失无关，也不能通过DNMT1过表达来预防。总之，这些观察结果表明了以下假设：成红细胞包含限制DNMT1甲基化能力的机制。我们建议通过以下三个目的检验这一假设：目标1：确定在红细胞基因组中5MC是否会通过酶TET2进行氧化，从而导致复制依赖性DNMT1抗性全球脱甲基化目标2：确定环蛋白依赖性Kinase Kinase diby phiprient in rybip2 in ry dip57kip2 equeLiDNNA的作用。脱甲基化。 AIM 3：确定在红细胞分化开始时加速的S期DNA合成的基本机制：是由发射复制起源数量增加而引起的，还是由复制叉进展的提高引起的。询问该过程是否受细胞周期蛋白依赖性激酶抑制剂p57KIP2调节。这项工作的资金将阐明如何调节全球甲基化模式，并可能在概念上为耐红细胞生成蛋白的贫血治疗提供新的途径。