Mechanisms of Chromatin Transcriptional Regulation

描述（由申请人提供）：基因表达的改变导致许多癌症，包括卵巢癌、膀胱癌、乳腺癌和结肠直肠癌，以及神经退行性疾病，如阿尔茨海默病。人类基因组形成染色质的动态组织调节转录起始和延伸，而染色质修饰、组装、拆卸和重塑的缺陷导致许多癌基因的错误调控。这使得染色质修饰复合物成为主要的化疗药物靶点之一。许多研究已经确定并关联了参与染色质转录调控（CTR）的成分，包括组蛋白变异、组蛋白翻译后修饰（PTMs）、组蛋白伴侣组装因子和染色质重塑因子。值得注意的是，基因、生化、结构和深度测序研究尚未完全揭示CTR的机制。我们假设核小体解包裹、组蛋白ptm、组蛋白变异体、组蛋白伴侣和染色质重塑子共同作用，显著影响TF占用和H2A-H2B异源二聚体交换，从而调节转录。我们已经开发了精确的化学工具和单分子测量能够确定CTR的机制和功能。使用这些方法，我们将确定组蛋白变体、ptm、伴侣和染色质重塑复合物共同作用的机制，以合作（加性和倍增性）、反合作和冗余性调节转录。我们在更新申请中提出以下具体目标：(1)确定核小体影响转录因子动力学的机制；(2)确定H2A的转录调控机制。Z, H3.3和核小体进出PTMs。(3)确定H2A-H2B异源二聚体交换和去除背后的转录调控机制。这些研究将为理解染色质转录调控和许多癌基因的错误调控背后的机制和功能相互作用提供基础。

DESCRIPTION (provided by applicant): Alterations in gene expression cause numerous cancers including ovarian, bladder, breast and colorectal tumors, as well as neurodegenerative conditions, such as Alzheimer's disease. The dynamic organization of the human genome into chromatin regulates transcription initiation and elongation, while defects in chromatin modifications, assembly, disassembly and remodeling results in the misregulation of many oncogenes. This has led to chromatin modifying complexes becoming one of the main chemotherapeutic drug targets. Numerous studies have identified and correlated the components involved in chromatin transcriptional regulation (CTR), which include histone variants, histone post-translational modifications (PTMs), histone chaperone assembly factors and chromatin remodeling factors. Remarkably, genetic, biochemical, structural and deep sequencing studies have not fully revealed the mechanisms of CTR. We hypothesize that nucleosome unwrapping, histone PTMs, histone variants, histone chaperones and chromatin remodelers function together to significantly influence TF occupancy and H2A-H2B heterodimer exchange to regulate transcription. We have developed precise chemical tools and single molecule measures capable of determining the mechanisms and functions of CTR. Using these methodologies, we will determine the mechanisms by which histone variants, PTMs, chaperones and chromatin remodeling complexes function together to cooperatively (additively and multiplicatively), anti-cooperatively and redundantly regulate transcription. We propose in the renewal application the following Specific Aims: (1) Determine the mechanisms by which nucleosomes influence transcription factor dynamics; (2) Determine the transcriptional regulatory mechanisms of H2A.Z, H3.3 and nucleosome entry-exit PTMs. (3) Determine the transcriptional regulator mechanisms behind H2A-H2B heterodimer exchange and removal. These studies will provide a foundation for understanding the mechanisms and functional interactions behind chromatin transcriptional regulation and the misregulation of numerous oncogenes.