Tissue biology studies of histone modification, nascent transcription, and post-transcription regulation

摘要 哺乳动物组织发育和成体再生所必需的基本细胞过程是 通常由mRNA水平的基因表达调控控制。每种的总mRNA水平 基因依赖于两种机制：主动（或“起始”）转录和转录后 RNA稳定性/降解（例如周转率）。新生转录本身受 招募组蛋白修饰酶和打开染色质的多个步骤，RNA聚合酶 II（Pol II）的起始和暂停，以及Pol II的释放进入生产性RNA延伸。多样化 调节总mRNA水平的机制可能在控制不同的生物学过程中是重要的。 过程和病理，但这在体内知之甚少。使用皮肤作为模型系统 我们将绘制RNA Pol II活性和新生转录的谱系特异性基因模式， 在没有细胞分离的情况下，在它们的天然组织环境中的特定细胞类型。此外，委员会认为， 我们将研究沿着成人组织干细胞的这些起始转录模式的变化 激活和分化途径，使用毛囊作为谱系原型。此外，我们的工作 将有助于剖析活性转录与转录后RNA的相对贡献 在体内特定细胞类型中的总mRNA水平的转换/稳定性。此外，我们将 确定一个已知的组蛋白抑制标记（H3 K9 me 3），在哺乳动物中知之甚少， 组织，作用于体内的新生转录和RNA Pol II暂停。我们将首次揭开 3种主要的H3 K9 me 3组蛋白甲基转移酶在皮肤中的生理作用 发育和体内平衡。最后，我们将研究H3 K9 me 3如何作用于新生的 使用我们新开发的小鼠遗传学工具和方法进行体内转录。我们 这项工作将为哺乳动物基因调控提供以前无法获得的机制性见解。 使用皮肤作为模型系统的组织生物学。

Abstract Basic cellular processes essential to mammalian tissue development and adult regeneration, are often controlled by gene expression regulation at the mRNA level. Total mRNA level for each gene depends on two mechanisms: active (or ‘nascent’) transcription and post-transcriptional RNA stability/degradation (e.g. turnover rates). Nascent transcription itself is regulated by multiple steps of recruiting histone-modifying enzymes and opening chromatin, RNA polymerase II (Pol II) initiation and pausing, and the release of Pol II into productive RNA elongation. Diverse mechanisms that regulate total mRNA level may be important in controlling distinct biological processes and pathologies, but this is poorly understood in vivo. Using skin as a model system we will map lineage-specific gene patterns of RNA Pol II activity and nascent transcription in specific cell-types within their natural tissue milieu in the absence of cell isolation. Furthermore, we will investigate changes in these nascent-transcription patterns along an adult tissue stem cell activation and differentiation path, using hair follicle as a lineage prototype. In addition, our work will help dissect relative contributions of active transcription vs post-transcriptional RNA turnover/stability to overall mRNA levels in specific cell types in vivo. Furthermore, we will determine how a known histone repressive mark (H3K9me3), poorly understood in mammalian tissues, acts on nascent transcription and RNA Pol II pausing in vivo. We will uncover for the first time the physiological role of the 3 main H3K9me3 histone methyl transferases in skin development and homeostasis. Finally, we will investigate how H3K9me3 acts on nascent transcription in vivo using our newly developed mouse genetics tools and methodologies. Our work will provide previously unavailable mechanistic insight into gene regulation in mammalian tissue biology using skin as a model system.