Epigenetic control mechanisms and cell-type-specific responsiveness of Wnt/ß-catenin target genes

Wnt/γ-catenin 靶基因的表观遗传控制机制和细胞类型特异性反应

• 批准号: 70366687
• 负责人: Professor Dr. Andreas Hecht
• 金额: --
• 依托单位: Institut für Molekulare Medizin und Zellforschung
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2008
• 资助国家: 德国
• 起止时间: 2007-12-31 至 2012-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/70366687?language=en
• 关键词: Epigenetic; control; mechanisms; cell; type

During embryonic development the same signal transduction mechanisms are repeatedly used to control a wide variety of differentiation processes. Depending upon cellular context any given signal transduction pathway acts upon only a subset of its potential targets. How is this selectivity achieved? We are using Wnt/β-catenin signaling and its nuclear effectors - β-catenin and the T-cell factors (TCFs) - as a paradigm to investigate this fundamental problem. Previous studies have shown that responsive and non-responsive states of Wnt/β-catenin-regulated genes coincide with characteristic patterns of DNA methylation, histone modifications, and promoter occupancy by TCFs. Therefore, epigenetic mechanisms may be used to separate functionally distinct groups of genes by regulating promoter accessibility for TCFs. The goal of the proposed project is to examine this hypothesis and to test the importance of epigenetic features for cell-type and stage-specific control of Wnt-regulated genes. To gain insight into causal relationships, we will establish temporal profiles of changes in chromatin modifications, TCF occupancy, and Wnt-inducibility which accompany functional transitions of Wnt/β-catenin targets in a cellular differentiation model. An extended characterization of cell-type-specific epigenetic landscapes will be undertaken in a locus-specific and domain-wide manner at Wnt/β-catenin target genes, and interdependencies between the generation of distinct chromatin structural states and promoter occupancy of TCFs will be further examined by analyzing alterations of structural and functional properties in response to depletion of either epigenetic modifiers or TCFs, and when association of TCFs with the promoter regions of stably transfected reporter genes is prevented by binding site mutation.

在胚胎发育过程中，相同的信号转导机制被重复用于控制多种分化过程，具体取决于细胞环境，任何给定的信号转导途径仅作用于其潜在靶标的子集。我们如何使用Wnt/来实现这种选择性？ β-连环蛋白信号传导及其核效应子 - β-连环蛋白和 T 细胞因子 (TCF) - 作为研究这一基本问题的范例，先前的研究表明 Wnt/β-连环蛋白的响应和非响应状态受到调节。基因与 DNA 甲基化、组蛋白修饰和 TCF 启动子占据的特征模式一致，因此，表观遗传机制可用于通过调节 TCF 的启动子可及性来分离功能不同的基因组。为了测试表观遗传特征对于 Wnt 调节基因的细胞类型和阶段特异性控制的重要性，为了深入了解因果关系，我们将建立染色质修饰、TCF 占用和变化的时间曲线。细胞分化模型中 Wnt 诱导性伴随着 Wnt/β-连环蛋白靶标的功能转变，将以位点特异性和全域方式在 Wnt/β-连环蛋白上进行细胞类型特异性表观遗传景观的扩展表征。目标基因，以及不同染色质结构状态的生成和 TCF 启动子占据之间的相互依赖性将通过分析结构和功能特性的变化来进一步检查，以响应表观遗传修饰剂或TCF，以及通过结合位点突变阻止 TCF 与稳定转染的报告基因启动子区域的关联。