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反复用于控制各种各样的分化过程。根据细胞环境，任何给定的信号转导途径仅作用于其潜在靶点的子集。这种选择性是如何实现的？我们正在使用Wnt/β-catenin信号及其核效应子- β-catenin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-catenin调节基因的应答和非应答状态与TCF的DNA甲基化、组蛋白修饰和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。拟议项目的目标是检验这一假设，并测试表观遗传特征对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，我们将建立细胞分化模型中伴随Wnt/β-连环蛋白靶点功能转变的染色质修饰、TCF占用和Wnt诱导的变化的时间曲线。将在Wnt/β-连环蛋白靶基因上以基因座特异性和全域方式进行细胞类型特异性表观遗传景观的扩展表征，并将通过分析响应于表观遗传修饰剂或TCF耗尽的结构和功能特性的改变，进一步检查不同染色质结构状态的产生与TCF的启动子占用之间的相互依赖性，以及当TCF与稳定转染的报告基因的启动子区的结合被结合位点突变阻止时。