美国加州大学旧金山分校Alexander Marson研究组取得一项新突破。他们发现动态基因回路调节T细胞静息和激活状态的转换。该项研究成果发表在2024年12月11日出版的《自然》上。

研究人员表示，细胞要保持独特的特性并对瞬时环境信号做出反应，需要对基因网络进行严密的调控。在人原代细胞中，这些对细胞外刺激做出反应的动态调控回路仍未得到很好的阐述。在T细胞中，不同的亚型必须对不同的信号做出反应，才能做出有效的免疫反应并维持体内平衡。

IL-2Rα是T细胞活化的典型标志物，其在促炎的效应T细胞中瞬时表达，而在抗炎的调节型T细胞中则组成性表达，因为T细胞活化需要IL-2Rα。已确定约90%的IL-2Rα调控因子在不同细胞类型和/或刺激状态下具有不同的作用，其中一部分甚至在不同条件下具有相反的作用。

研究人员利用单细胞转录组学对特定情境筛选结果进行集合扰动，将特定因子表征为整体静息或激活的调控因子，并构建了特定状态的调控网络。MED12是Mediator复合体的一个成分，它是关键调控因子的动态协调者，调节不同T细胞环境中不同调控因子组的表达。免疫沉淀-质谱分析发现，MED12与组蛋白甲基化COMPASS复合物有相互作用。

组蛋白甲基化和编码关键特异性调控因子（包括静息维持因子KLF2和多功能调控因子MYC）的基因的表达，都需要MED12。利用CRISPR敲除MED12减弱了细胞在静息和激活之间的状态转换，并防止激活诱导的细胞死亡。

总之，该研究利用在不同条件下进行的CRISP筛选，确定了调控T细胞静息和激活所需的动态基因回路。

附：英文原文

Title: Central control of dynamic gene circuits governs T cell rest and activation

Author: Arce, Maya M., Umhoefer, Jennifer M., Arang, Nadia, Kasinathan, Sivakanthan, Freimer, Jacob W., Steinhart, Zachary, Shen, Haolin, Pham, Minh T. N., Ota, Mineto, Wadhera, Anika, Dajani, Rama, Dorovskyi, Dmytro, Chen, Yan Yi, Liu, Qi, Zhou, Yuan, Swaney, Danielle L., Obernier, Kirsten, Shy, Brian R., Carnevale, Julia, Satpathy, Ansuman T., Krogan, Nevan J., Pritchard, Jonathan K., Marson, Alexander

Issue&Volume: 2024-12-11

Abstract: The ability of cells to maintain distinct identities and respond to transient environmental signals requires tightly controlled regulation of gene networks1,2,3. These dynamic regulatory circuits that respond to extracellular cues in primary human cells remain poorly defined. The need for context-dependent regulation is prominent in T cells, where distinct lineages must respond to diverse signals to mount effective immune responses and maintain homeostasis4,5,6,7,8. Here we performed CRISPR screens in multiple primary human CD4+ T cell contexts to identify regulators that control expression of IL-2Rα, a canonical marker of T cell activation transiently expressed by pro-inflammatory effector T cells and constitutively expressed by anti-inflammatory regulatory T cells where it is required for fitness9,10,11. Approximately 90% of identified regulators of IL-2Rα had effects that varied across cell types and/or stimulation states, including a subset that even had opposite effects across conditions. Using single-cell transcriptomics after pooled perturbation of context-specific screen hits, we characterized specific factors as regulators of overall rest or activation and constructed state-specific regulatory networks. MED12 — a component of the Mediator complex — serves as a dynamic orchestrator of key regulators, controlling expression of distinct sets of regulators in different T cell contexts. Immunoprecipitation–mass spectrometry revealed that MED12 interacts with the histone methylating COMPASS complex. MED12 was required for histone methylation and expression of genes encoding key context-specific regulators, including the rest maintenance factor KLF2 and the versatile regulator MYC. CRISPR ablation of MED12 blunted the cell-state transitions between rest and activation and protected from activation-induced cell death. Overall, this work leverages CRISPR screens performed across conditions to define dynamic gene circuits required to establish resting and activated T cell states.

DOI: 10.1038/s41586-024-08314-y

Source: https://www.nature.com/articles/s41586-024-08314-y