Transcriptional Control of the Mouse aA-crystallin locus

摘要 这项研究计划的长期目标是阐明协调的全球机制， 调节眼透镜发育和分化所需基因的表达。以来 透镜是一种简单的组织，仅由两种成熟细胞类型组成，这些机制的阐明 提供了深入了解这些过程所需的分化更复杂的组织， 为开发和设计尖端的生物学新途径奠定了基础。 研究范围从干细胞替代疗法到靶向癌症治疗。中心前提 这一建议的一个重要方面是，透镜细胞的分化依赖于DNA- 将转录因子与FGF和BMP信号转导通路结合， 形成成熟的眼透镜所需的数百个基因的表达。哺乳动物透镜的标志 纤维细胞的分化是a-和B-/g-晶体蛋白的积累，作为关键的透镜结构和保护 蛋白质、细胞伸长以及细胞核和其他细胞器的降解。在区分透镜时， 一组基因在转录上被打开和关闭，而这一过程的中心部分是由 通过染色质DNA的可及性与转录因子和染色质结合， 重塑酶在这些因子中，c-Maf、Pax 6、Prox 1、c-Jun、Etv 5和Smads共同起作用， 系统调节单个晶体蛋白和其他晶体蛋白的空间和时间表达的单位。 眼睛透镜的分化和功能所必需的基因。具体而言，该提案将：1） 阐明染色质在调节透镜分化特异性基因表达中的功能作用 在全基因组水平上，（2）定义DNA结合转录因子的特定作用及其作用 在透镜分化过程中形成“开放”染色质区域，以及（3）鉴定和表征 透镜细胞核中不同拓扑相关结构域（TADs）的作用和功能，包括 转录工厂，核仁和剪接斑点，作为透镜分化的关键组成部分。 拟议的研究得到了强有力的初步数据的支持，表明“开放”的形成。 关键透镜分化基因的启动子和增强子中的染色质区域， 基本转录因子的可及性和功能以及离散TADs的鉴定 包括来自不同染色体的晶状体蛋白基因座，以协调它们在透镜纤维细胞中的表达。 这些结果将首次定义晶状体特异性基因表达所需的顺序事件 通过转录因子和改变的染色质构象之间的相互作用， 深入了解透镜分化所需的透镜纤维细胞核的3D组织，以及 揭示驱动透镜纤维细胞去核的新的调节机制。

ABSTRACT The long-term goal of this research program is to elucidate the global mechanisms that coordinately regulate the expression of genes required for the development and differentiation of the ocular lens. Since the lens is a simple tissue composed of only two mature cell types, elucidation of these mechanisms provides insight into those processes required for the differentiation of far more complex tissues and provides the groundwork for the development and design of cutting-edge new avenues of biological research ranging from stem-cell replacement therapies to targeted cancer treatments. The central premise of this proposal is that differentiation of lens cells is dependent on the coordinated interactions of DNA- binding transcription factors with FGF and BMP signal transduction pathways to orchestrate lens-specific expression of hundreds of genes required to form the mature eye lens. The hallmark of mammalian lens fiber cell differentiation is accumulation of a- and b-/g-crystallins as key lens structural and protective proteins, cellular elongation, and degradation of nuclei and other organelles. In differentiating lens, specific groups of genes are transcriptionally turned on and off, and the central part of this process is controlled through the accessibility of chromatin DNA to associate with transcription factors and chromatin remodeling enzymes. Among these factors, c-Maf, Pax6, Prox1, c-Jun, Etv5, and Smads, act together as a unit to systematically regulate the spatial and temporal expression of individual crystallins and other genes essential for the differentiation and function of the eye lens. Specifically, this proposal will: 1) elucidate the functional role that chromatin plays in regulating lens differentiation-specific gene expression at the genome-wide level, (2) define the specific roles of DNA-binding transcription factors and their roles in formation of “open” chromatin regions during lens differentiation, and (3) identify and characterize the role and function of distinct topologically associating domains (TADs) in lens cell nuclei, including transcriptional factories, nucleoli and splicing speckles, as critical components of the lens differentiation. The proposed studies are supported by strong preliminary data demonstrating the formation of “open” regions of chromatin in the promoters and enhancers of key lens differentiation genes allowing accessibility and function of essential transcription factors and the identification of discrete TADs comprised of crystallin loci from different chromosomes to coordinate their expression in lens fiber cells. The results will define for the first time those sequential events required for lens-specific gene expression through the interplay between transcription factors and altered chromatin conformation, will provide novel insights into the 3D-organization of lens fiber cell nuclei that are required for lens differentiation, and uncover novel regulatory mechanisms that drive lens fiber cell denucleation.