Chromatin architectural protein CTCF and regulation of skin development and tumorigenesis

项目总结 这个项目的长期目标是了解皮肤上皮干细胞是如何建立独特的 分化为特化细胞系过程中的基因激活和沉默模式，以及这些模式是如何 在皮肤再生和肿瘤形成过程中，遗传程序会被重新组织。 现在人们普遍认为，除了信号/转录因子介导的机制外，世系- 特定的基因表达程序也受表观遗传调控，即通过共价DNA/组蛋白 基因修饰，以及通过基因及其增强子元件在细胞核内的空间排列。 增强子-启动子相互作用是提供功能和结构框架的关键决定因素 用于由谱系特异性转录因子控制的细胞特异性转录。然而，增强子-启动子 在细胞向恶性转化的过程中，调控网络实质上是重新组织的，其中包括 基因启动子异常暴露于不适当的调控元件，导致激活前... 癌基因，以及肿瘤抑制基因的沉默。 CCCTC结合因子(CTCF)是一种核心结构蛋白，在细胞周期中起着关键作用。 控制增强子/启动子相互作用的建立和维持。CTCF基因频繁突变 在癌症中，它的肿瘤抑制活性的取消有助于癌症的发展和进展。 我们的初步数据表明，CTCF在小鼠和人的表皮中都有表达，而 Krt14驱动的CTCF遗传消融导致皮肤发育、表皮屏障 维持，和肿瘤的发生。在这个多PI提案中，我们将测试一个假设，即CTCF作为关键 控制增强子-启动子调控网络的建立和维持的决定因素 皮肤上皮干细胞及其后代在发育和出生后动态平衡过程中的变化 这样的网络会导致皮肤肿瘤的发生。我们将通过两个具体目标来解决这一假设： 1.确定CTCF在建立和维持特定血统的更高等级中的作用 染色质结构、增强子-启动子调控网络与基因表达 发育过程中皮肤上皮细胞的数量以及与毛发周期相关的皮肤再生。 2.阐明CTCF在基因表达调控、3D染色质组织和细胞周期调控中的作用 肿瘤发生过程中皮肤上皮细胞中增强子-启动子的相互作用。 这个项目将对我们目前关于表观遗传机制的知识产生根本性的影响 调节干细胞分化和肿瘤形成过程中的基因组重组，并将促进 作为治疗皮肤病的新范例的新型表观遗传药物的开发进展。

PROJECT SUMMARY The long-term goal of this project is to understand how epithelial stem cells in the skin establish distinct patterns of gene activation and silencing during their differentiation into specialized cell lineages and how these genetic programs are re-organized during skin regeneration and tumorigenesis. It is now widely accepted that in addition to signaling/transcription factor-mediated mechanisms, lineage- specific gene expression programs are also regulated epigenetically, i.e., via covalent DNA/histone modifications, as well as via spatial arrangements of the genes and their enhancer elements in the nucleus. Enhancer-promoter interactions serve as key determinants providing functional and structural frameworks for cell-specific transcription controlled by lineage-specific transcription factors. However, enhancer-promoter regulatory networks are substantially re-organized during cell transition towards malignancy, which include an aberrant exposure of gene promoters to inappropriate regulatory elements resulting in activation of pro- oncogenes, as well as in silencing of the tumor suppressor genes. CCCTC-binding factor (CTCF) serves as one of the core architectural proteins that plays a key role in the control the establishment and maintenance of enhancer/promoter interactions. CTCF gene is frequently mutated in cancers, and abrogation of its tumor-suppressor activity contributes to cancer development and progression. Our preliminary data demonstrate that CTCF is expressed in both mouse and human epidermis, while Krt14-driven Ctcf genetic ablation results in severe alterations in skin development, epidermal barrier maintenance, and tumorigenesis. In this multi-PI proposal, we will test a hypothesis that CTCF serves as critical determinant that control the establishment and maintenance of the enhancer-promoter regulatory networks in skin epithelial stem cells and their progenies during development and postnatal homeostasis, while alterations in such networks result in skin tumorigenesis. We will address this hypothesis via two Specific Aims: 1. Define the roles of CTCF in the establishment and maintenance of lineage-specific higher-order chromatin structure, enhancer-promoter regulatory networks and gene expression in distinct populations of skin epithelial cells during development and hair cycle-associated skin regeneration. 2. Delineate the roles for Ctcf in regulation of gene expression, 3D chromatin organization and enhancer-promoter interactions in the skin epithelial cells during tumorigenesis. This project will have a fundamental impact on our current knowledge of epigenetic mechanisms that regulate genome reorganization in stem cells during their differentiation and tumorigenesis and will promote the progress towards the development of novel epigenetic drugs as a new paradigm for treatment of skin disorders.