Roles of chromatin regulators in governing histone acylation and mouse development

许多生物如植物和动物的细胞都含有一种叫做核的清晰结构，因此这些生物是真核生物(即含核生物)。在这样的生物体中，遗传物质在细胞核内被组织成一个复杂的结构，称为染色质。对这种结构的调节对生物体的发育和生存至关重要。染色质调节剂的鉴定提高了分析它们在生物体发育和生存中的作用的紧迫性。因此，我们采取了遗传学的方法来了解染色质调节因子组蛋白乙酰转移酶的生物学功能。它们是作为乙酰化催化剂的酶，乙酰化是在称为组蛋白的蛋白质的赖氨酸残基中添加化学基团“乙酰基”的过程。其中一种酶被称为HBO1，它促进组蛋白H3蛋白质第14位的乙酰基与赖氨酸的加成。这种修饰在各种生物中都很重要，例如苍蝇、老鼠和人类。HBO1的活性由一种名为BRPF2的激活剂控制。重要的是，我们发现HBO1也催化类似乙酰化的修饰(如丙酰化)，而BRPF2促进这种新的修饰。*假设*我们假设BRPF2通过刺激HBO1的新修饰来调节大脑发育。有了这个假设，我们将在未来5年内追求以下具体目标，并着眼于了解组蛋白修饰如何有助于动物的发育和生存。*具体目标*1)检验组蛋白H3修饰对全基因组染色质的调控。利用小鼠和人类细胞，我们将进行各种DNA测序实验，以研究新的赖氨酸14上的组蛋白H3修饰如何有助于全基因组染色质调节。2)确定BRPF2和HBO1在小鼠脑发育中的作用。BRPF2和HBO1在大脑中的水平都很高，但目前尚不清楚它们在大脑中可能扮演什么角色。小鼠Brpf2或Hbo1基因的失活会导致突变胚胎的死亡，因此我们将利用一种特殊的技术来产生前脑缺失Brpf2或Hbo1基因的突变小鼠。为此，我们获得了Brpf2基因缺失的相关小鼠。我们将使用一种新的基因编辑技术来产生需要删除Hbo1基因的小鼠。之后，将研究这两个基因在小鼠大脑(特别是大脑部分)中的功能。*研究计划将阐述Hbo1和Brpf2基因如何调节赖氨酸14上新的组蛋白H3修饰和小鼠大脑发育。由此产生的知识将阐明染色质调节如何有助于大脑发育，这是一个对动物和人类都很重要的自然过程。这将为我们在理解动物和人类发育过程中不同组蛋白修饰的相互作用方面追求长期利益奠定坚实的基础。**

Cells in many organisms such as plants and animals contain a clear structure called nucleus, so these organisms are eukaryotic (i.e. nucleus-containing). In such organisms, the genetic material is organized into a complex structure, known as chromatin, in the nucleus. Regulation of this structure is critical for development and survival of the organisms. Identification of chromatin regulators has raised the urgency to analyze their roles in organismal development and survival. We have thus taken genetic approaches to understand biological functions of chromatin regulators called histone acetyltranferases. They are enzymes functioning as catalysts for acetylation, a process to add the chemical group "acetyl" to lysine residues of proteins called histones. One such enzyme is known as HBO1, which promotes addition of an acetyl group to lysine at position 14 of a protein called histone H3. This modification is important in various organisms, such as flies, mice and humans. The activity of HBO1 is controlled by an activator called BRPF2. Importantly, we found that HBO1 also catalyzes acetylation-like modifications (such as propionylation) and that BRPF2 promotes such novel modifications.******Hypothesis***We hypothesize that BRPF2 regulates brain development by stimulating the novel modifications by HBO1. With the hypothesis, we will pursue the following specific objectives in the coming 5 years, with the long-term vision to understand how histone modifications contribute to animal development and survival.******Specific Objectives***1) Examine genome-wide chromatin regulation by histone H3 modifications. Using mouse and human cells, we will carry out various DNA sequencing experiments to investigate how the novel histone H3 modifications at lysine 14 contribute to genome-wide chromatin regulation.******2) Determine roles of BRPF2 and HBO1 in mouse brain development. Both BRPF2 and HBO1 are produced to high levels in the brain, but it remains unclear what roles they may have there. Inactivation of the mouse Brpf2 or Hbo1 gene causes death of mutant embryos, so we will utilize a special technique to generate mutant mice with the Brpf2 or Hbo1 gene deleted in the forebrain. We have obtained related mice to delete at the Brpf2 gene for this purpose. We will use a new gene-editing technique to generate mice required to delete the Hbo1 gene. After that, functions of the two genes in the mouse brain (especially the cerebral part) will be investigated.******Significance***The research program will address how the Hbo1 and Brpf2 genes regulate novel histone H3 modifications at lysine 14 and mouse brain development. The resulting knowledge will shed light on how chromatin regulation contributes to brain development, a natural process important for animals and humans. This will set a solid stage to pursue our long-term interests in understanding the cross-talk of different histone modifications during animal and human development.**