Genetic Aspects of DNA Methylation

超出提供的空间。DNA甲基化是高等真核生物正常发育所必需的。哺乳动物的X-失活和基因组印记需要甲基化，而异常甲基化与癌症有关。在人类中，DNA甲基转移酶(MTase)突变导致ICF综合征，甲基化DNA结合蛋白(MBP)MeCP2突变导致Rett综合征。DNA甲基化在粗糙脉孢菌中是必不可少的，这有助于遗传学研究。DNA甲基化缺陷突变体(DIM)的分离为真核生物甲基化的控制和功能研究提供了新的思路。最近，DIM-5作为组蛋白H3MTase的鉴定表明，组蛋白修饰控制DNA甲基化。这项研究的目的是利用这一杰出的模式系统来阐明真核生物中DNA甲基化的机制。有价值的新资源和工具将促进这项工作，包括：1.几乎完整的脉孢子虫基因组序列，2.识别DNA甲基化缺陷的新的基于平息的系统，3.用于反向遗传学的突变过程，RIP(重复诱导点突变)，4.针对修饰的组蛋白的抗体，以及5.强大的新分析方法(例如，质谱仪和微阵列分析)。该项目的具体目标是：1.鉴定与RIP突变的DNA结合的蛋白质(MRBP-1、MBP-2、MBP-3)；2.鉴定营养细胞中负责所有已检测到的甲基化的DIM-2 DNA MTase，以及有性细胞中RIP所需的潜在DNA MTase RID；3.对组蛋白H4、H3、H_2B和H_2A的N末端进行突变分析，以评估它们在体内DNA甲基化中的作用；4.确定组蛋白甲基化在DNA甲基化中的作用；5.阐明组蛋白乙酰化和磷酸化在DNA甲基化中的作用；6.检测染色质重塑在DNA甲基化中的可能作用；7.鉴定DNA甲基化机制中的其他成分。表演网站========================================Section End===========================================

EXCEED THE SPACE PROVIDED. DNA methylation is required for normal development of higher eukaryotes. Methylation is required for X-inactivation and genomic imprinting in mammals, and abnormal methylation is associated with cancer. In humans, mutation of a DNA methyltransferase (MTase) causes ICF syndrome and mutation of the methyI-DNA binding protein (MBP) MeCP2 causes Rett syndrome. DNA methylation is dispensable in the fungus Neurospora crassa, facilitating genetic studies. Isolation of Neurospora mutants defective in DNA methylation (dim) has led to insights into the control and function of methylation in eukaryotes. Most recently, identification of DIM-5 as a histone H3 MTase demonstrated that histone modifications control DNA methylation. The goal of the proposed research is to elucidate the mechanism of DNA methylation in eukaryotes by taking advantage of this outstanding model system. The work will be facilitated by valuable new resources and tools including: 1. the nearly complete sequence of the Neurospora genome, 2. a novel quelling-based system to recognize DNA methylation defects, 3. a mutagenic process, RIP (repeat-induced point mutation), for reverse-genetics, 4. antibodies specific for modified histones and 5. powerful new analytical methods (e.g., mass spectrometry and microarray analysis). Specific aims of the project are: 1. To identify and genetically characterize proteins that bind methylated and RIP-mutated DNA (MRBP-1, MBP-2, MBP-3); 2. To characterize the DIM-2 DNA MTase, which is responsible for all detected methylation in vegetative cells, and the potential DNA MTase RID, which is required for RIP in sexual cells; 3. To carry out mutational analyses of the N-terminal tails of histones H4, H3, H2B and H2A to assess their role in DNA methylation in vivo; 4. To determine the role of histone methylation in DNA methylation; 5. To elucidate the role of histone acetylation and phosphorylation in DNA methylation; 6. To test the possible role of chromatin remodeling in DNA methylation; 7. To identify additional components of the DNA methvlation machinerv. PERFORMANCE SITE ========================================Section End===========================================