Molecular functions of Tcf-1 in DP thymocytes

DP胸腺细胞中Tcf-1的分子功能

• 批准号: 10507783
• 负责人: Fotini Gounari
• 金额: $ 41.5万
• 依托单位: MAYO CLINIC ARIZONA
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-11-22 至 2024-10-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10507783
• 关键词: 3-Dimensional; Ablation; Binding; Binding Proteins; Binding Sites; CD8B1 gene; Cell Lineage; Cell Proliferation; Cells; Chromatin; Chromatin Structure; Complex; DNA; DNA Binding; DNA Binding Domain; DNA Sequence; DNA-Binding Proteins; Data; Development; Developmental Process; Differentiated Gene; Disease; E-Box Elements; Enhancers; Epigenetic Process; Eukaryota; Event; Family; Gene Activation; Gene Expression; Gene Expression Profile; Genes; Genetic Transcription; Goals; Immune; Immunity; Individual; Internet; Knowledge; Length; Literature; Mediating; Molecular; Molecular Conformation; Mus; Mutate; Nuclear; Outcome; Process; Promoter Regions; Protein Isoforms; Proteins; Regulation; Regulatory Element; Research; Role; Series; Shapes; Site; T cell differentiation; T cell transcription factor 1; T-Cell Development; T-Lymphocyte; Testing; Therapeutic Intervention; Thymocyte Development; Thymus Gland; Tissues; beta catenin; cdc Genes; gene repression; genetic regulatory protein; genome-wide; lymphoid enhancer-binding factor 1; member; molecular modeling; novel; programs; promoter; protein complex; recruit; thymocyte

PROJECT SUMMARY Thymic development is highly responsible for shaping a healthy and balanced T cell immunity. Like other developmental processes it involves coordinated changes in the linear and three-dimensional chromatin organization that allow stage specific transcription events. A central regulator at nearly every stage of T cell differentiation is the DNA binding protein Tcf-1. Studies proposed here will elucidate how Tcf-1 coordinates the action of epigenetic and transcription regulators to instruct the differentiation of CD4+CD8+ DP thymocytes. Tcf- 1 modulates the chromatin landscapes and transcription profiles directly through binding to its conserved DNA sequence, or indirectly in association with other regulatory proteins. DP thymocytes express two forms of Tcf- 1, the full length Tcf-1p45 protein that binds β-catenin, and a short Tcf-1p38 isoform that does not. Lef-1, another member of the Tcf/Lef family of regulators, also expressed in thymocytes has overlapping functions with Tcf-1. In addition Tcf-1 cooperates with the HLH domain DNA binding protein HEB at the DP thymocyte stages through the sharing of ~7000 DNA binding sites genome wide. The presence of both Tcf-1 and HEB at the shared sites is necessary to promote chromatin accessibility and regulate gene transcription. The direct Tcf-1- HEB binding to their conserved motifs in enhancer regions of T cell differentiation genes promotes their expression. By contrast Tcf-1-HEB recruitment to sites lacking conserved motifs, in promoter regions of cell- cycle genes reduces their expression and cell proliferation. Such opposing transcription outcomes likely involve Tcf-1-HEB recruitment to DNA in the context of distinct regulatory complexes. The composition of complexes containing Tcf-1 and HEB, the specific Tcf-1 isoform involved in each complex, and which functions are redundant between Tcf-1 and Lef-1, still remain to be elucidated. The intricate functional co-operation between these factors likely also involves the ability of Tcf-1 and Lef-1 to bend the DNA helix at their binding site which may modulate the 3D chromatin conformation, and define the proximity between co-operating factors and regulatory elements. These findings and the existing literature provide strong premise for the hypothesis that DP thymocyte development is enabled by the cooperation of Tcf-1 isoforms with protein complexes that shape the 3D chromatin structure to differentially regulate gene expression. Two specific aims are proposed. Aim 1 will determine the how Tcf-1p45 and, Tcf-1p33, co-operate with Lef-1 and HEB in the context of distinct regulatory complexes to establish the epigenetic and transcription profile of DP thymocytes and control their developmental progression. Aim 2: will elucidate the roles of Tcf-1p45, Tcf-1p33, Lef-1 with HEB shaping the chromatin conformation, and how this function promotes DP thymocyte development. The proposed studies are expected to highlight a completely new layer in the molecular regulation of DP thymocytes.

项目摘要 胸腺发育高度负责塑造健康且平衡的T细胞免疫。像其他 发育过程涉及线性和三维染色质的协调变化 允许阶段特定转录事件的组织。几乎每个T细胞阶段的中央调节器 分化是DNA结合蛋白TCF-1。这里提出的研究将阐明TCF-1如何坐标 表观遗传和转录调节剂的作用指导CD4+ CD8+ DP胸腺细胞的分化。 tcf- 1通过与其配置的DNA结合直接调节染色质景观和转录曲线 序列，或间接与其他调节蛋白相关。 DP胸腺细胞表达两种形式的TCF- 1，结合β-catenin的全长TCF-1P45蛋白，而没有的短TCF-1P38同工型。 LEF-1，另一个 TCF/LEF调节剂家族的成员也表达在胸腺细胞中，其功能与TCF-1重叠。 另外，TCF-1与HLH结构域DNA结合蛋白HEB在DP胸腺细胞阶段合作 通过共享约7000个DNA结合位点基因组宽。 TCF-1和HEB的存在 共享位点对于促进染色质的可及性和调节基因转录是必要的。直接的TCF-1- HEB与T细胞分化基因增强子区域中其配置的基序结合促进 表达。相比之下，在细胞的启动子区域中，TCF-1-HEB招募缺乏构成基序的地点 循环基因降低其表达和细胞增殖。这种相反的转录结果可能涉及 在不同的调节复合物的背景下，TCF-1-HEB募集到DNA。复合物的组成 包含TCF-1和HEB，每个复合物涉及的特定TCF-1同工型，哪些功能是 TCF-1和LEF-1之间的冗余仍然有待阐明。复杂的功能合作 这些因素可能还涉及TCF-1和LEF-1在其结合位点弯曲DNA螺旋的能力，该位点的能力 可能调节3D染色质构象，并定义合作因素和 监管要素。这些发现和现有文献为以下假设提供了有力的前提。 DP胸腺细胞发育是通过与蛋白质复合物合作的合作 3D染色质结构对不同的调节基因表达。提出了两个具体目标。目标1 将在不同调节的情况下确定如何与LEF-1和HEB合作的TCF-1P45和TCF-1P33 建立DP胸腺细胞的表观遗传和转录谱的复合物并控制其 发展进展。 AIM 2：将阐明TCF-1P45，TCF-1P33，LEF-1的角色，HEB塑造 染色质构象以及该功能如何促进DP胸腺细胞发育。提出的研究 预计将在DP胸腺细胞的分子调节中突出一个全新的层。