Molecular Mechanisms Employed by TRIM28 to Maintain Epigenetic Information through Different Stages of Embryonic Development

TRIM28 在胚胎发育不同阶段维持表观遗传信息的分子机制

• 批准号: 1456543
• 负责人: MARIA GARCIA-GARCIA
• 金额: $ 83.2万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-01 至 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1456543&HistoricalAwards=false
• 关键词: Molecular; Mechanisms; Employed; TRIM28; Maintain

How information in genomes is decoded during embryogenesis is one of the greatest mysteries of humankind. Central to this problem is an understanding of how gene expression is regulated. Certain genes are controlled by chemical modifications that are introduced before fertilization. These marks to DNA (also called chromatin marks or genomic imprints) in eggs and sperm are transmitted from parents to children and constitute an important mechanism for the control of gene expression across generations. While research in the last 50 years has uncovered the complexity of chromatin marks, information is still lacking about the factors that recognize and interpret these marks to activate or repress the imprinted genes. Preliminary evidence has revealed a novel role for a specific protein as a regulator of imprinted gene expression. By further defining the requirements for involvement of this protein, this research program will expand fundamental knowledge of the processes and factors that mediate control of gene expression across generations. In addition to enhancing understanding of a fundamental problem in embryonic development, this program of study fosters research by students of all levels. Additionally, both the lead researcher and students participate in several outreach activities to disseminate knowledge of developmental biology. Shortly after fertilization, mammalian embryos undergo a genome-wide demethylation event that involves the enzymatic removal of methyl groups from methyl-cytosine DNA residues. The removal of these epigenetic marks allows the reprogramming of the zygotic genome, an essential process for embryogenesis to begin. However, a number of genomic loci, including imprinted genes, need to preserve epigenetic information for the new organism to develop properly. The transcriptional repressor TRIM28 has recently emerged as a key regulator of imprinted gene expression. However, the mechanisms employed by this transcription factor are still unclear. This proposal aims to resolve the requirements of TRIM28 for genomic imprinting at different developmental stages and the molecular mechanisms used by this transcriptional regulator to maintain epigenetic information in developing mouse embryos. Experiments in Specific Aim 1 will analyze the stage-specific requirements of TRIM28 for imprinting control by analyzing the effects of conditional depletion of Trim28 at different times during embryonic development. In Specific Aim 2, the mechanisms by which TRIM28 controls secondary DMR methylation at the Dlk1-Gtl2 locus will be investigated through epistatic analysis. Results from these experiments will provide novel insight not only into the roles of TRIM28, but also into the mechanisms that regulate genomic imprinting.

基因组中的信息在胚胎发生过程中如何解码是人类最大的谜团之一。这个问题的核心是了解基因表达是如何调节的。某些基因由受精前引入的化学修饰控制。这些DNA标记（也称为染色质标记或基因组印记）在卵子和精子中从父母传递给子女，并构成控制基因表达的重要机制。虽然过去50年的研究已经揭示了染色质标记的复杂性，但仍然缺乏有关识别和解释这些标记以激活或抑制印记基因的因素的信息。初步证据显示，一种特定的蛋白质作为印记基因表达的调节剂具有新的作用。通过进一步定义这种蛋白质参与的要求，该研究计划将扩大对跨代介导基因表达控制的过程和因素的基本知识。除了加强对胚胎发育中基本问题的理解外，该研究计划还促进了各级学生的研究。此外，首席研究员和学生都参加了一些推广活动，以传播发育生物学知识。受精后不久，哺乳动物胚胎经历全基因组去甲基化事件，涉及从甲基胞嘧啶DNA残基中酶促去除甲基。这些表观遗传标记的去除允许合子基因组的重编程，这是胚胎发生开始的一个重要过程。然而，一些基因组位点，包括印记基因，需要保留表观遗传信息，以使新生物体正常发育。转录抑制因子TRIM28最近已成为印记基因表达的关键调节因子。然而，这种转录因子的作用机制尚不清楚。该提案旨在解决TRIM28在不同发育阶段对基因组印记的需求以及该转录调节因子用于维持发育中小鼠胚胎的表观遗传信息的分子机制。具体目标1中的实验将通过分析胚胎发育过程中不同时间条件性耗尽Trim28的影响来分析TRIM28对印迹控制的阶段特异性要求。在具体目标2中，将通过上位性分析研究TRIM 28控制Dlk1-Gtl2基因座处的继发DMR甲基化的机制。这些实验的结果不仅将为TRIM28的作用提供新的见解，还将为调节基因组印记的机制提供新的见解。