Histone mRNA Regulation in Development

摘要 在细胞周期中，适当的调节组蛋白的生物合成是协调的关键 染色质组装和DNA复制。组蛋白生产过剩或生产不足 蛋白质导致复制压力和基因组不稳定，这是导致 癌症的发展。在这份提案中，我们对 复制依赖(RD)组蛋白mRNA的生物合成及其过程 在动物发育的背景下，在细胞周期中受到调节。RD-组蛋白mRNAs 是动物细胞中唯一没有Polya尾巴的真核mRNAs，而是以 保守的杆环结构。相比之下，组蛋白变体的mRNAs，如H3.3 和H2A.Z是由不受细胞周期调控的多腺苷化mRNAs编码的。 独特的RD-组蛋白mRNA3‘端的产生是由于An的活性 进化保守的一组前RNA加工因子。编码这五种基因的 RD-组蛋白聚集在后生动物基因组中，转录和前... 组蛋白信使核糖核酸生物合成所需的信使核糖核酸加工因子 聚集在这些基因簇上的核体(组蛋白基因体或HLb)。我们 将决定配位合成RD-组蛋白mRNAs的要求 在果蝇中使用生化和遗传方法，特别关注 HLB在组蛋白转录和前信使核糖核酸加工中的作用。组蛋白 基因簇提供了一个系统，在这个系统中，人们可以很容易地研究一个紧密的 在所有水平的mRNA生物合成中受调控的一组基因，来自组织 细胞核内的基因通过激活转录、前mRNA处理和 转录终止。我们的果蝇实验范式允许在体内 对基因表达中的这些基本过程的询问 在其他实验系统中不可用。

ABSTRACT Proper regulation of histone biosynthesis during the cell cycle is critical for coordinating chromatin assembly and DNA replication. Overproduction or underproduction of histone protein results in replication stress and genome instability that contributes to the development of cancer. In this proposal, we undertake a comprehensive analysis of replication-dependent (RD) histone mRNA biosynthesis and how this process is regulated during the cell cycle in the context of animal development. RD-histone mRNAs are the only eukaryotic mRNAs in animal cells that lack a polyA tail, ending instead in a conserved stem loop structure. In contrast, mRNAs for histone variants such as H3.3 and H2A.Z are encoded by polyadenylated mRNAs that are not cell cycle regulated. Generation of the unique RD-histone mRNA 3’ end results from the activity of an evolutionary conserved set of pre-RNA processing factors. The genes encoding all five RD-histone proteins are clustered in metazoan genomes, and transcription and pre- mRNA processing factors required for histone mRNA biosynthesis are organized into a nuclear body (the histone locus body or HLB) that assembles at these gene clusters. We will determine the requirements for the coordinate synthesis of the RD-histone mRNAs using both biochemical and genetic approaches in Drosophila, with a particular focus on the role that the HLB plays in histone transcription and pre-mRNA processing. Histone gene clusters provide a system in which one can readily study the expression of a tightly regulated set of genes at all levels of mRNA biosynthesis, from the organization of genes within the nucleus through activation of transcription, pre-mRNA processing and transcription termination. Our Drosophila experimental paradigm permits the in vivo interrogation of these fundamental processes in gene expression in ways that are unavailable in other experimental systems.