Cell Cycle Regulation of Histone Gene Expression

描述（由申请人提供）：进入S期是调控哺乳动物细胞增殖的关键事件。G1/S期组蛋白基因表达的控制激活对于新生DNA的染色质包装至关重要。我们的项目已经确定hif -p是组蛋白基因的主要转录调节因子，组蛋白是周期蛋白E/ CDK2/ p220NPAT通路的终点分子，hif -p缺乏会损害细胞周期在S期的进展。hif - p的发现和表征是我们项目最重要的成就之一，提出的研究将建立在这一重大结果的基础上，为细胞周期控制开辟一个新的维度。我们的中心假设是周期蛋白E/ CDK2/ p220NPAT/ HiNF-P基因调控级联是细胞周期的主要途径，其功能是实现组蛋白H4的生物合成能力，以支持DNA作为染色质的包装。为了解决这一假设，我们将结合生化、分子、细胞和体内遗传策略来确定hif - p /p220NPAT途径如何支持S期激活和进展。首先，我们将描述控制hif -p /p220NPAT复合物活性的蛋白-蛋白相互作用结构域和翻译后修饰，以及介导组蛋白基因转录和mRNA加工的亚核位点（“组蛋白位点体”）调控信号的原位整合（Specific Aim 1）。然后，我们将研究hif - p缺乏如何影响正常细胞和肿瘤细胞的细胞周期进程，并解决hif - p参与调节细胞增殖的相关机制（Specific Aim 2）。为了确定hif - p通路的体内相关性，我们将研究hif - p在胚胎发生和出生后生长期间是否对体内正常发育很重要（Specific Aim 3）。这三个提出的目标旨在提供对细胞周期蛋白E/CDK2/p220NPAT/HiNF-P通路在正常和肿瘤细胞中细胞增殖的分子、细胞和生物学贡献的综合理解。公共卫生相关性：细胞增殖受一系列复杂和相互依赖的生化事件调控，这些生化事件涉及细胞周期阶段基因表达的特异性修饰。组蛋白基因的s期特异性表达在时间和功能上都与DNA复制耦合。通过hif - p和p220NPAT对组蛋白基因转录的细胞周期依赖性调节为G1/S期组蛋白合成的诱导提供了初始限速步骤。我们正在研究的hif - p依赖机制从根本上代表了参与细胞周期控制的新途径。我们的研究将深入了解控制S期进展能力的机制，并可能为选择性治疗疾病（特别是生长控制受损的癌症）提供新的靶点。

DESCRIPTION (provided by applicant): Entry into S phase is a key event for regulation of mammalian cell proliferation. The controlled activation of histone gene expression at the G1/S phase transition is essential for chromatin packaging of nascent DNA. Our program has identified HiNF-P as the principal transcriptional regulator of histone genes, the end-point molecule for the cyclin E/ CDK2/ p220NPAT pathway, and HiNF-P deficiency impairs cell cycle progression through S phase. The discovery and characterization of HiNF-P represents one of the most important accomplishments of our program and the proposed studies will build on this major result to open a new dimension to cell cycle control. Our central hypothesis is that the cyclin E/ CDK2/ p220NPAT/ HiNF-P gene regulatory cascade is a principal cell cycle pathway that functions to achieve competency for histone H4 biosynthesis to support packaging of DNA as chromatin. To address this hypothesis, we will combine biochemical, molecular, cellular and in vivo genetic strategies to define how the HiNF-P/p220NPAT pathway supports S phase activation and progression. First, we will characterize protein-protein interaction domains and post-translational modifications that control the activity of the HiNF-P/p220NPAT complex, as well as the in situ integration of regulatory signals at subnuclear sites ('Histone Locus Bodies') that mediate histone gene transcription and mRNA processing (Specific Aim 1). We will then examine how HiNF-P deficiency affects cell cycle progression in normal and tumor cells and address HiNF-P related mechanisms involved in regulating cell proliferation (Specific Aim 2). To establish the in vivo relevance of the HiNF-P pathway, we will investigate whether HiNF-P is important for normal development in vivo during embryogenesis and post-natal growth (Specific Aim 3). The three proposed aims are designed to provide an integrated understanding of the molecular, cellular, and biological contributions of the cyclin E/CDK2/p220NPAT/HiNF-P pathway to cell proliferation in normal and tumor cells. PUBLIC HEALTH RELEVANCE: Cell proliferation is regulated by a complex and interdependent series of biochemical events involving cell cycle-stage specific modifications in gene expression. The S-phase specific expression of histone genes is both temporally and functionally coupled with DNA replication. Cell cycle dependent modulation of histone gene transcription via HiNF-P and p220NPAT provides the initial rate-limiting step in the induction of histone protein synthesis at the G1/S phase transition. The HiNF-P dependent mechanisms we are investigating represent fundamentally novel pathways involved in cell cycle control. Our studies will provide insight into mechanisms that control competency for S phase progression and may yield novel targets for selective treatment of diseases, particularly cancer, in which growth control is compromised.