GENETICS OF DNA METHYLATION PATTERNING IN ARABIDOPSIS

拟南芥 DNA 甲基化模式的遗传学

• 批准号: 6490194
• 负责人: STEVEN E JACOBSEN
• 金额: $ 21.41万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 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/6490194
• 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

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起着关键作用。这在几种表观遗传基因调节系统中很重要，包括亲本基因组印记，X染色体灭活以及转座子的沉默和其他多个副本DNA。甲基化也在肿瘤细胞生物学中起作用，因为肿瘤通常表现出特定基因的基因组广泛的脱甲基化和高甲基化。 尽管重要性很重要，但对如何建立和维护适当的甲基化模式知之甚少。拟议的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适当基因组甲基化模式的基因。 鉴于鉴于国际拟南芥基因组测序工作，拟南芥是进行大规模诱变实验的能力，并鉴于甲基化突变体和克隆的DNA甲基转移酶基因的收集，拟南芥是对这种类型研究的最佳生物之一。 我们发现了一个可操纵的表观遗传系统，其中两个关键的花卉调节基因的甲基化状态可以通过几种影响总体基因组甲基化的突变来改变。 令人惊讶的是，我们发现降低总体基因组甲基化的突变会导致超人和agamous的密集高甲基化。 此外，我们发现了一类新的突变，这些突变也会引起超人基因座的密集过度甲基化，但不会影响整体基因组甲基化水平。 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.鉴于植物和哺乳动物之间的基因组甲基化机制是在植物和哺乳动物之间保守的，因此对植物基因高甲基化的研究可能会很好地阐明动物中发生的相似过程，尤其是癌细胞中基因高甲基化的表面相似现象。