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Silencing of transposons in mammalian germ cells

哺乳动物生殖细胞中转座子的沉默

基本信息

批准号：
7409171
负责人：
TIMOTHY H BESTOR
金额：
$ 23.67万
依托单位：
COLUMBIA UNIVERSITY HEALTH SCIENCES
依托单位国家：
美国
项目类别：
财政年份：
2007
资助国家：
美国
起止时间：
2007-05-01 至 2009-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7409171
关键词：
Affinity Alleles Angelman Syndrome Arts Award Binding Biological Code Common Neoplasm Complex Cues DNA Methyltransferase DNA Modification Methylases DNA Sequence Defect Development Disease Embryo Ensure Epigenetic Process Event Excision Exons Failure Future Gametogenesis Gene Silencing Gene Targeting Genes Genetic Genetic Transcription Genome Genomic Imprinting Genomics Genotype Germ Cells Germ Lines H19 gene Homologous Gene Human Hydatidiform Mole Hypermethylation Knockout Mice Knowledge L1 Elements Lead Maintenance Malignant Neoplasms Mass Spectrum Analysis Measures Meiosis Messenger RNA Methods Methylation Monozygotic Twinning Monozygotic twins Mus Mutate Mutation Nature Pattern Physiological Prader-Willi Syndrome Procedures Proteins RNA RNA Recognition Motif Rate Recurrence Regulation Reporting Research Retroposon Role Site Staging Structure Syndrome Testing Time Transcript Tumor Suppressor Genes Variant base blastocyst cancer cell cancer genome demethylation embryonic stem cell homologous recombination human disease imprint interest male mammalian genome mutant promoter repository research study tumor

项目摘要

DESCRIPTION (provided by applicant): Ectopic gene silencing can contribute to disease. Human cancer cells frequently contain genomes that have undergone a net loss of m5C and there are many reports of tumor suppressor genes that are normal in sequence but not expressed; such genes have methylated promoters. Many associations between abnormalities of genomic methylation patterns and cancer have been reported The nature of the alterations that lead to global demethylation with focal hypermethylation in many common tumors is completely unknown, but must involve the gain or loss of regulatory factors; none of the DNA methyltransferases has been shown to be mutated or silenced in cancer. Methylation and ectopic gene silencing have also been attributed a role in genotype- independent phenotypic diversity, as in discordance in monozygotic twins. This suggests errors in targeting of gene silencing during gametogenesis or early in development, again by unknown regulatory factors. The identification of Dnmt3L as an essential factor in the establishment of genomic methylation patterns in germ cells provides the first opportunity to isolate factors that regulate de novo methylation and to define the cues that direct methylation to specific sequences. We will use a new and minimally perturbed interaction screen and state-of-the-art protein identification by mass spectrometry to identify factors that complex with Dnmt3L, and we will apply new genetic methods in the functional analysis of Ecat11, an especially interesting factor found to interact with Dnmt3L in preliminary studies. Ectopic silencing or activation in tumors of factors that control de novo methylation is a likely cause of the disrupted methylation patterns often seen in cancer genomes. The identification of factors that regulate de novo methylation is an issue of immediate importance in the field of mammalian (and human) epigenetics. The function of the mammalian genome depends on the accurate establishment and maintenance of genomic methylation patterns during gametogenesis and early development. Abnormal methylation patterns are common in many malignant tumors; it is possible that re-expression of germ-cell or embryonic methylation regulators is responsible for tumor-specific methylation abnormalities. Errors in the establishment of methylation imprints in germ cells can cause Angelman syndrome, Prader-Willi syndrome, or Beckwith-Wiedeman syndrome, and mutations in genes for imprinting factors cause recurrent familial biparental hydatidiform moles, in which paternal genomic imprints are imposed on the maternal genome (Judson et al., 2002; Bestor and Bourc'his, 2006). Errors in the establishment or maintenance of genomic methylation patterns are currently believed to contribute to genotype-independent phenotypic variation, especially in psychiatric illness where rates of discordance in monozygotic twins often exceeds 40% (Meissner, 1965). The biological importance of genomic methylation patterns has only recently become clear, but at this time almost nothing is known of the mechanisms by which they are established. The studies described here are almost certain to identify factors that regulate de novo methylation in the male germ line.

描述（由申请人提供）：异位基因沉默可能导致疾病。人类癌细胞经常包含已经经历了m5 C的净损失的基因组，并且有许多关于序列正常但不表达的肿瘤抑制基因的报道;这些基因具有甲基化的启动子。基因组甲基化模式异常与癌症之间的许多关联已被报道。在许多常见肿瘤中导致全局去甲基化与局灶性超甲基化的改变的性质是完全未知的，但必须涉及调节因子的获得或丧失;没有DNA甲基转移酶被证明在癌症中突变或沉默。甲基化和异位基因沉默也被认为在基因型无关的表型多样性中起作用，如在单卵双胞胎中的不一致性。这表明在配子发生或发育早期，基因沉默的靶向错误，同样是由未知的调控因素。Dnmt 3L作为在生殖细胞中建立基因组甲基化模式的重要因子的鉴定提供了第一次机会来分离调节从头甲基化的因子并定义将甲基化引导至特定序列的线索。我们将使用一种新的和最小干扰的相互作用筛选和最先进的蛋白质鉴定质谱法来鉴定与Dnmt 3L复合的因子，我们将在Ecat 11的功能分析中应用新的遗传方法，Ecat 11是一种在初步研究中发现与Dnmt 3L相互作用的特别有趣的因子。肿瘤中控制从头甲基化的因子的异位沉默或激活可能是癌症基因组中常见的甲基化模式被破坏的原因。鉴定调控从头甲基化的因子是哺乳动物（和人类）表观遗传学领域中的一个直接重要的问题。哺乳动物基因组的功能依赖于配子发生和早期发育过程中基因组甲基化模式的准确建立和维持。异常甲基化模式在许多恶性肿瘤中很常见;生殖细胞或胚胎甲基化调节因子的重新表达可能是肿瘤特异性甲基化异常的原因。在生殖细胞中建立甲基化印记的错误可引起Angelman综合征、Prader-Willi综合征或Beckwith-Wiedeman综合征，并且印记因子的基因突变引起复发性家族性双亲葡萄胎，其中父亲基因组印记强加于母亲基因组（Judson et al. 2002年; Becomes和Bourc'his，2006年）。目前认为基因组甲基化模式的建立或维持中的错误有助于基因型非依赖性表型变异，特别是在精神疾病中，其中单卵双胞胎的不一致率通常超过40%（Meissner，1965）。基因组甲基化模式的生物学重要性直到最近才变得清楚，但目前对它们建立的机制几乎一无所知。这里描述的研究几乎可以肯定地确定调节男性生殖系中从头甲基化的因素。