Department of Immunology, Duke University Medical Center, Durham, NC.
Department of Immunology, Duke University Medical Center, Durham, NC
J Exp Med. 2019 Jan 7;216(1):231-243. doi: 10.1084/jem.20181402. Epub 2018 Dec 13.
Expression of and is tightly regulated in developing T cells to mediate TCR gene assembly. Here we have investigated the molecular mechanisms governing the assembly and disassembly of a transcriptionally active RAG locus chromatin hub in CD4CD8 thymocytes. and gene expression in CD4CD8 thymocytes depends on and promoter activation by a distant antisilencer element (ASE). We identify GATA3 and E2A as critical regulators of the ASE, and Runx1 and E2A as critical regulators of the promoter. We reveal hierarchical assembly of a transcriptionally active chromatin hub containing the ASE and RAG promoters, with recruitment and expression dependent on assembly of a functional ASE- framework. Finally, we show that signal-dependent down-regulation of RAG gene expression in CD4CD8 thymocytes depends on Ikaros and occurs with disassembly of the RAG locus chromatin hub. Our results provide important new insights into the molecular mechanisms that orchestrate RAG gene expression in developing T cells.
在 T 细胞发育过程中， 和 的表达受到严格调控，以介导 TCR 基因的组装。在这里，我们研究了调控 CD4+CD8+胸腺细胞中转录活性 RAG 基因座染色质中心组装和拆卸的分子机制。CD4+CD8+胸腺细胞中的 和 基因表达依赖于远距离反沉默元件 (ASE) 激活 和 启动子。我们确定 GATA3 和 E2A 是 ASE 的关键调节因子，而 Runx1 和 E2A 是 启动子的关键调节因子。我们揭示了包含 ASE 和 RAG 启动子的转录活性染色质中心的层次组装，其中 募集和表达依赖于功能 ASE-骨架的组装。最后，我们表明，CD4+CD8+胸腺细胞中信号依赖性下调 RAG 基因表达依赖于 Ikaros，并伴随着 RAG 基因座染色质中心的拆卸。我们的研究结果为调控 T 细胞发育过程中 RAG 基因表达的分子机制提供了重要的新见解。
