Roles of chromatin regulators in governing histone acylation and mouse development

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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.**