Investigating the functions of histone acetylation in genome organization and leukemogenesis

染色质结构在控制细胞表型中起着中心作用。癌症细胞中表观基因组的改变和染色质调节因子的频繁突变突出了这一点。尽管表观遗传学最近取得了进展，但我们目前对染色质组织如何促进基因表达、基因组稳定性和癌症发生缺乏详细的机制理解，这阻碍了有效治疗的发展。组蛋白的乙酰化被认为可以促进基因组过程如转录、复制和修复的调控因子进入局部DNA。赖氨酸23上组蛋白H3的乙酰化（H3K23ac）在哺乳动物染色质上的高丰度使其在其他乙酰化位点中脱颖而出，这挑战了通常认为的局部DNA可及性作用，相反表明其在更全局的基因组组织过程中起作用。敲除放置H3K23ac、KAT6A和KAT6B的酶具有很强的发育表型。此外，产生含有KAT6A-或kat6b融合蛋白的染色体易位可诱导急性髓系白血病。总之，这些观察结果表明H3K23ac在调节细胞表型中的重要作用尚未被探索。我假设H3K23ac赋予了一种特定的染色质结构，这种结构确保了正确的基因组组织，而这种结构的错误调节诱发了白血病。为了研究这一点，我将开发新的细胞和小鼠模型，并将结合尖端的遗传学，基因组学和细胞生物学方法来研究H3K23ac在正常和白血病细胞中的作用。此外，我将建立几个关键的方法（染色质环境分析和组蛋白基因突变），这将改变哺乳动物组蛋白修饰的研究方式。从长远来看，拟议的工作将为回答染色质结构和功能如何影响细胞表型和诱导疾病的基本问题提供强有力的概念和方法基础。

Chromatin structure plays a central role in controlling cell phenotype. This is highlighted by altered epigenomes and frequent mutations in chromatin regulators in cancer cells. Despite recent advances in epigenetics, we currently lack detailed mechanistic understanding of how chromatin organization contributes to gene expression, genome stability and cancer initiation, which hinders development of efficient therapies. Acetylation of histone proteins is considered to facilitate local DNA access for regulators of genomic processes such as transcription, replication, and repair. Acetylation of histone H3 on lysine 23 (H3K23ac) stands out among other acetylation sites due its high abundance in mammalian chromatin, which challenges the generally assumed local DNA accessibility role and instead suggests a function in more global processes of genome organization. Knockouts of the enzymes placing H3K23ac, KAT6A and KAT6B, have strong developmental phenotypes. Moreover, chromosomal translocations generating KAT6A- or KAT6B-containing fusion proteins induce acute myeloid leukemia. Together, these observations indicate an important yet unexplored role of H3K23ac in regulating cell phenotype. I hypothesize that H3K23ac confers a specific chromatin structure that ensures correct genomic organisation and which misregulation induces leukemia. To investigate this, I will develop novel cell and mouse models and will use a combination of cutting-edge genetic, genomic and cell biology approaches to investigate the role of H3K23ac in normal and leukemic cells. In addition, I will establish several key methodologies (chromatin environment profiling and histone gene mutagenesis) that will transform the way histone modifications are investigated in mammals. In the long-term, the proposed work will serve as a strong conceptual and methodological foundation to answer the fundamental questions of how chromatin structure and function influence cell phenotype and induce disease.