Inheritance of histone post-translational modifications

组蛋白翻译后修饰的遗传

• 批准号: RGPIN-2018-04907
• 负责人: Howe, LeAnn
• 金额: $ 7.29万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=744259
• 关键词: Inheritance; histone; post; translational; modifications

Multicellular organisms are comprised of different cell types that share the same genome. Cell identity is therefore dictated by the subset of genes that are transcribed in each cell type. Factors that regulate gene expression can be divided into two classes: those that maintain genes in an “ON” state and those that maintain genes in an “OFF” state. The major question in the field of gene regulation is how these proteins maintain transcription patterns in replicating cells, when genome duplication requires unwinding of DNA strands and disruption of associated proteins.Eukaryotic DNA is packaged with a conserved class of proteins, known as histones. Histones are post-translationally modified by enzymes known as "writers", and different post-translational modifications (PTMs) are associated with gene activation and repression. Histone PTMs hold much promise as heritable markers of gene expression states. Histones displaced during DNA replication are deposited close to their original location on nascent DNA. Genetic studies in yeasts and Drosophila have identified numerous writer enzymes that play roles in inheritance of gene expression states. Despite this evidence however, we have failed to determine whether survival of histone PTMs following genome duplication is a general phenomenon. Instead, many studies have shown that histone PTMs are lost during DNA replication due to the presence of “eraser” enzymes, which remove histone PTMs. Interestingly, eraser enzymes may not be ubiquitously present and data exist demonstrating that the activity of erasers is regulated by the environment. The broad goal of our proposed research is to determine whether histone PTMs are heritable and under what conditions. To achieve our goal we will: 1) confirm that active histone PTMs are heritable genome-wide, 2) determine whether alteration of eraser activity by the environment affects inheritance of histone PTMs and 3) test whether histone PTMs regulate re-establishment of transcription patterns following DNA replication. We will use S. cerevisiae as a model organism because histones, writers, and erasers are conserved from yeasts to humans and because the experiments we propose would be extremely difficult and expensive to conduct in mammalian cells. Significance: Epigenetics refers to the inheritance of gene expression states without alteration of underlying DNA sequence. The epigenetic regulation of DNA-dependent processes has been intensely studied over the last two decades. However, despite the great interest in epigenetic inheritance, the underlying mechanisms involved remain largely unknown. The research described in this proposal will determine whether histone PTMs can and do mediate epigenetic inheritance and will help prepare seven higher-education students for successful careers in research.

多细胞生物体由共享相同基因组的不同细胞类型组成。因此，细胞特性是由在每种细胞类型中转录的基因子集决定的。调节基因表达的因子可以分为两类：一类是维持基因处于“开启”状态的因子，另一类是维持基因处于“关闭”状态的因子。基因调控领域的主要问题是，当基因组复制需要解开DNA链和破坏相关蛋白质时，这些蛋白质如何在复制细胞中维持转录模式。真核DNA包装着一类保守的蛋白质，称为组蛋白。组蛋白被称为编写者的酶进行翻译后修饰，不同的翻译后修饰(PTM)与基因激活和抑制有关。组蛋白PTM作为基因表达状态的可遗传标记很有希望。在DNA复制过程中被替换的组蛋白被放置在靠近它们在新生DNA上的原始位置。对酵母菌和果蝇的遗传学研究发现，许多编写酶在基因表达状态的遗传中发挥作用。然而，尽管有这些证据，我们仍未能确定组蛋白PTM在基因组复制后存活是否是一种普遍现象。相反，许多研究表明，由于“橡皮擦”酶的存在，组蛋白PTM在DNA复制过程中会丢失，这种酶可以去除组蛋白PTM。有趣的是，橡皮擦酶可能并不是无处不在的，而且有数据表明，橡皮擦的活动受到环境的调节。我们提出的研究的主要目标是确定组蛋白PTM是否可遗传以及在什么条件下可遗传。为了实现我们的目标，我们将：1)证实活性的组蛋白PTM在全基因组范围内是可遗传的，2)确定环境中橡皮擦活性的改变是否影响组蛋白PTM的遗传，以及3)测试组蛋白PTM是否调控DNA复制后转录模式的重建。我们将使用酿酒酵母作为模式生物，因为从酵母菌到人类，组蛋白、编写器和橡皮擦都是保守的，而且我们提出的在哺乳动物细胞中进行的实验将极其困难和昂贵。意义：表观遗传学是指在不改变潜在DNA序列的情况下遗传基因表达状态。在过去的二十年里，DNA依赖过程的表观遗传调控已经得到了广泛的研究。然而，尽管表观遗传引起了人们的极大兴趣，但所涉及的潜在机制在很大程度上仍不清楚。这项提案中描述的研究将确定组蛋白PTMS是否能够并确实介导表观遗传，并将帮助七名受过高等教育的学生为在研究领域取得成功做好准备。