The Mute button: Turning down the volume of histone expression

项目总结 在DNA复制过程中，细胞不仅必须复制其DNA，还必须复制 打包它的基因组。为了满足这种对快速组蛋白生物合成的极高需求， 所有真核细胞都协调复制依赖(RD)组蛋白基因簇的高表达 在S-细胞分裂周期的阶段。调控RD-组蛋白基因的表达水平 在S期对于保持基因组的完整性和正常的细胞周期进程是重要的， 因为组蛋白过多或过少都会导致毒性作用，如增强DNA损伤敏感性 或者细胞周期停滞。而RD-组蛋白基因的转录激活已经被 其特征是，对细胞退出S时的负调控知之甚少 发生在S时期的转录调控。我的初步研究表明 果蝇蛋白MUT(人类Yarp/Gon4L的同源物)是一种 组蛋白基因的负转录调控因子。我发现失去沉默的夫妻 S期RD-组蛋白基因在果蝇胚胎中的表达我假设哑巴既是 将RD-组蛋白表达限制在S期，并调节S的表达水平 相位。这项提议试图揭示哑巴通过什么机制压制RD- 组蛋白基因，以及这种抑制如何与细胞周期联系在一起。使用跨学科的 方法，哑巴在细胞和分子水平上的抑制机制将是 利用基因组、荧光成像、遗传和蛋白质组学技术的组合进行探索 在果蝇模型系统中。这个项目将加深我们对组蛋白作用的理解。 后生动物中的基因调控，并提供对调控机制的洞察 这一高度保守的细胞过程。

PROJECT SUMMARY During DNA replication, a cell must replicate not only its DNA, but also the nucleosomes that package its genome. To meet this extremely high demand for rapid histone protein biosynthesis, all eukaryotes coordinate high expression of replication-dependent (RD) histone gene clusters during S-phase of the cell division cycle. Regulating the level of expression of RD-histone genes during S-phase is important for maintaining genomic integrity and normal cell cycle progression, as too many or too few histones lead to toxic effects such as enhanced DNA damage sensitivity or cell cycle arrest. While the transcriptional activation of RD-histone genes has been characterized, little is known about the negative regulation that occurs as cells exit S-phase or the modulation of transcription that occurs during S-phase. My preliminary research has shown the Drosophila protein Mute (a homologue of human Yarp/Gon4L) is a prime candidate for a negative transcriptional regulator of RD-histone genes. I have found that loss of Mute uncouples expression of RD-histone genes from S-phase in Drosophila embryos. I hypothesize Mute is both restricting RD-histone expression to S-phase as well as regulating levels of expression during S- phase. This proposal seeks to uncover the mechanisms through which Mute represses RD- histone genes and how this repression is connected to the cell cycle. Using an interdisciplinary approach, the mechanisms of Mute’s repression at both the cellular and molecular levels will be explored using a combination of genomic, fluorescent imaging, genetic, and proteomic techniques in the Drosophila model system. This project will enhance our understanding of the role of histone gene regulation in metazoans and provide insight into the mechanisms that govern the regulation of this highly conserved cellular process.