GENETICS OF DNA METHYLATION PATTERNING IN ARABIDOPSIS

拟南芥 DNA 甲基化模式的遗传学

基本信息

批准号：
6343088
负责人：
STEVEN E JACOBSEN
金额：
$ 20.83万
依托单位：
UNIVERSITY OF CALIFORNIA LOS ANGELES
依托单位国家：
美国
项目类别：
财政年份：
2000
资助国家：
美国
起止时间：
2000-01-01 至 2004-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/6343088
关键词：
Arabidopsis DNA methylation alleles developmental genetics eukaryote gene complementation gene expression gene mutation genetic mapping genetic markers genetic regulatory element genetically modified plants genomic imprinting molecular cloning plant genetics polymerase chain reaction restriction fragment length polymorphism yeast two hybrid system

项目摘要

Cytosine methylation is an epigenetic modification of DNA that plays a key role in cellular memory throughout the eukaryotes. It is important in several epigenetic gene regulatory systems including parental genomic imprinting, X-chromosome inactivation, and the silencing of transposons and other multiple copy DNAs. Methylation also plays a role in tumor cell biology, as tumors often show both genome wide demethylation and hypermethylation of specific genes. Despite its importance, little is known about how proper methylation patterns are established and maintained. The long-term goal of the proposed research is to use Arabidopsis thaliana as a model genetic system to identify and study genes involved in proper genomic methylation patterning. Arabidopsis is one of the best organisms for studies of this type, given the ability to do large-scale mutagenesis experiments, given the international Arabidopsis genome sequencing efforts, and given the collection of methylation mutants and cloned DNA methyltransferase genes which are already available. We have discovered a manipulable epigenetic system in which the methylation state of two key floral regulatory genes, SUPERMAN and AGAMOUS, can be altered by several mutations that affect overall genomic methylation. Surprisingly, we find that mutations that reduce overall genomic methylation, cause dense hypermethylation of SUPERMAN and AGAMOUS. Furthermore, we have discovered a new class of mutations that also cause dense overmethylation of the SUPERMAN locus, but that do not affect overall genomic methylation levels. The specific objectives of this proposal are 1) to map and study mutations which cause hypermethylation of SUPERMAN, with the goal of cloning the corresponding genes, 2) to use large scale mutagenesis to identify genes that are important in maintaining the dense patterns of methylation at SUPERMAN, 3) to study the role of SUPERMAN methylation during normal development, and 4) to determine cis acting sequences which cause targeting of SUPERMAN for methylation. Given the likelihood that genomic methylation mechanisms are conserved between plants and mammals, studies of plant gene hypermethylation may well shed light on similar processes occurring in animals, especially the superficially similar phenomenon of hypermethylation of genes in cancerous cells.

胞嘧啶甲基化是 DNA 的表观遗传修饰，在整个真核生物的细胞记忆中发挥着关键作用。它在多种表观遗传基因调控系统中非常重要，包括亲本基因组印记、X 染色体失活以及转座子和其他多拷贝 DNA 的沉默。甲基化在肿瘤细胞生物学中也发挥着重要作用，因为肿瘤通常表现出全基因组去甲基化和特定基因的高甲基化。尽管它很重要，但人们对如何建立和维持正确的甲基化模式知之甚少。拟议研究的长期目标是使用拟南芥作为模型遗传系统来识别和研究参与正确基因组甲基化模式的基因。拟南芥是进行此类研究的最佳生物体之一，因为它具有进行大规模诱变实验的能力，考虑到国际拟南芥基因组测序的努力，以及考虑到已经可用的甲基化突变体和克隆的DNA甲基转移酶基因的收集。我们发现了一个可操纵的表观遗传系统，其中两个关键的花调控基因 SUPERMAN 和 AGAMOUS 的甲基化状态可以通过影响整体基因组甲基化的几个突变来改变。令人惊讶的是，我们发现降低整体基因组甲基化的突变会导致 SUPERMAN 和 AGAMOUS 的密集高甲基化。此外，我们还发现了一类新的突变，它们也会导致 SUPERMAN 基因座密集的过度甲基化，但不会影响整体基因组甲基化水平。该提案的具体目标是 1) 绘制和研究导致 SUPERMAN 超甲基化的突变，目的是克隆相应的基因，2) 使用大规模诱变来识别对维持甲基化密集模式非常重要的基因。 SUPERMAN，3) 研究 SUPERMAN 甲基化在正常发育过程中的作用，4) 确定导致 SUPERMAN 甲基化靶向的顺式作用序列。鉴于基因组甲基化机制在植物和哺乳动物之间可能是保守的，对植物基因高甲基化的研究很可能揭示动物中发生的类似过程，特别是癌细胞中表面上相似的基因高甲基化现象。