Systems-wide analysis of histone lysine 2-hydroxyisobutyrylation pathway

 描述(申请人提供)：组蛋白翻译后修饰(PTM，或组蛋白标记)对染色质结构和功能的动态调节至关重要。组蛋白修饰过程的失调会导致许多疾病的发生，如癌症、心血管疾病和神经系统疾病。我们最近报道了一种新的进化保守的组蛋白标记，赖氨酸2-羟基异丁酰化(KHIB)。我们发现Khib在人类和小鼠的63个组蛋白赖氨酸残基中都存在，比被广泛研究的组蛋白乙酰化(KAc)和甲基化(KME)位点的已知数量更多。我们还获得了多条证据，表明组蛋白Khib具有重要而独特的生物学功能：在雄性生殖细胞分化过程中，这类组蛋白修饰显示出与广泛研究的组蛋白Kac不同的基因组分布；它与活性基因有关。 H4K8hib与其对应的H4K8ac相比，是一个更好的基因高表达指标；组蛋白Khib可以依赖于2-羟基异丁酰辅酶A的方式指导体外转录，这表明组蛋白Khib影响染色质结构和转录活性；组蛋白Khib在嗜热四膜虫的转录活跃和转录沉默染色质中，在不同的细胞周期阶段和小鼠精子发生期间有不同的谱。这些结果表明，组蛋白Khib在结构和力学上与组蛋白Kac不同。调控组蛋白Khib途径的主要成员将在表观遗传学研究中开辟新的天地，并提高我们对细胞生理学和人类疾病的理解。在拟议的研究中，我们将使用综合方法研究组蛋白Khib途径。我们将鉴定组蛋白Khib调节酶和组蛋白Khib标记的直接结合蛋白。我们还将调查关键的组蛋白Khib标记在小鼠基因组中的基因组分布，并将这些数据与研究得很好的组蛋白乙酰化和甲基化标记进行比较。由于我们在表观基因组学、生物化学、蛋白质组学、干细胞生物学等领域的广泛专业知识，以及我们产生的巨大初步成果，我们的团队能够很好地开展这一项目。这项研究将通过揭示关键的调控元件来克服组蛋白Khib途径生物学研究的主要障碍，并可能描述新的表观遗传机制，可能类似于组蛋白Kac和Kme途径的特征。

 DESCRIPTION (provided by applicant): Histone post-translational modification (PTM, or histone mark) is critical to dynamic modulation of chromatin structure and function. Dysregulation of histone modification processes contributes to the development of many diseases, such as cancer, cardiovascular and neurological diseases. We recently reported a new, evolutionarily-conserved histone mark, lysine 2-hydroxyisobutyrylation (Khib). We showed that Khib is present among 63 histone lysine residues in both human and mouse, more than the known numbers of the widely studied histone acetylation (Kac) and methylation (Kme) sites. We also obtained multiple lines of evidence that suggest important and unique biological functions of histone Khib: this class of histone modification shows distinct genomic distributions from the widely studied histone Kac during male germ cell differentiation; it is associated with active gene transcription and H4K8hib is a better indicator for high gene expression than its corresponding H4K8ac; histone Khib can direct in vitro transcription in a manner dependent on 2-hydroxyisobutyryl CoA, suggesting that histone Khib impacts chromatin structure and transcriptional activity; histone Khib has different profiles between transcriptionally active and transcriptionally silent chromatin in Tetrahymena thermophile, in different cell cycle stages, and during mouse spermotogenesis. These results suggest that histone Khib is structurally and mechanistically different from histone Kac. The major players regulating histone Khib pathway would break new ground in epigenetic research and improve our understanding of cellular physiology and human disease. In the proposed research, we will study histone Khib pathway using an integrated approach. We will identify histone Khib-regulatory enzymes and direct binding proteins of histone Khib marks. We will also investigate genomic distributions of key histone Khib marks in mouse genome, and compare these data with those of the well-studied histone acetylation and methylation marks. Our team is well positioned to carry out this project, because of our extensive expertise in the areas of epigenomics, biochemistry, proteomics, stem cell biology, and the tremendous preliminary results we generated. This study will overcome a major hurdle to study biology of histone Khib pathway by revealing key regulatory elements and likely characterize novel epigenetic mechanisms, perhaps analogous to the characterization of histone Kac and Kme pathways.