"Hit-and-Run" transcription: de novo transcription initiated by a transient bZIP1 "hit" persists after the "run".
"Hit-and-Run" transcription: de novo transcription initiated by a transient bZIP1 "hit" persists after the "run".
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DOI：
10.1186/s12864-016-2410-2
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发表时间：
2016-02-03
期刊：
影响因子：
4.4
通讯作者：
Coruzzi GM
中科院分区：
文献类型：
--
作者：
Doidy J;Li Y;Neymotin B;Edwards MB;Varala K;Gresham D;Coruzzi GM
动态转录调控对于生物体对环境信号的反应至关重要，但仍然难以捕获。这种转录调控是由控制大型基因调控网络的主转录因子（TF）介导的。最近，我们描述了一种名为“肇事逃逸”的动态 TF 监管模式。该模型提出主 TF 可以与一组靶标瞬时相互作用，但这些瞬时靶标的转录在 TF 从靶标启动子解离后继续进行。然而，仍然缺乏验证瞬时 TF 靶标活性转录的实验证据。在这里，我们通过跟踪响应 TF 核导入而产生的 RNA 从头合成，表明在短暂的 TF 与靶标相互作用后，主动转录仍在继续。为此，我们引入了亲和标记的 4-硫尿嘧啶 (4tU) 核碱基，以在条件 TF 核导入后特异性分离新合成的转录本。因此，我们扩展了 TARGET 系统（转录因子的全基因组效应瞬时检测报告）以包含 4tU 标记，并将这项新技术命名为 TARGET-tU。我们的原理验证示例是主要的 TF 基本亮氨酸拉链 1 (bZIP1)，它是植物代谢信号的中央整合器。使用 TARGET-tU，当 bZIP1 不再可检测到与其靶标结合时，我们捕获了响应 bZIP1 核导入而产生的新合成的 mRNA。因此，从头转录组学的分析表明，bZIP1 可能充当催化剂 TF 来启动转录复合物（“命中”），之后 RNA 聚合酶的活性转录继续进行，而 TF 不会与基因启动子结合（“运行”）。我们的研究结果为瞬时 TF 靶标的主动转录支持“打了就跑”的行动模式提供了实验证据。这种动态调节模型允许主转录因子催化传播对环境变化的快速而广泛的转录反应。因此，通过瞬时 TF-靶标相互作用产生的从头转录本的功能读出使我们能够捕获全基因组转录控制的新模型。本文的在线版本 (doi:10.1186/s12864-016-2410-2) 包含补充材料，可供授权用户使用。
Dynamic transcriptional regulation is critical for an organism’s response to environmental signals and yet remains elusive to capture. Such transcriptional regulation is mediated by master transcription factors (TF) that control large gene regulatory networks. Recently, we described a dynamic mode of TF regulation named “hit-and-run”. This model proposes that master TF can interact transiently with a set of targets, but the transcription of these transient targets continues after the TF dissociation from the target promoter. However, experimental evidence validating active transcription of the transient TF-targets is still lacking. Here, we show that active transcription continues after transient TF-target interactions by tracking de novo synthesis of RNAs made in response to TF nuclear import. To do this, we introduced an affinity-labeled 4-thiouracil (4tU) nucleobase to specifically isolate newly synthesized transcripts following conditional TF nuclear import. Thus, we extended the TARGET system (Transient Assay Reporting Genome-wide Effects of Transcription factors) to include 4tU-labeling and named this new technology TARGET-tU. Our proof-of-principle example is the master TF Basic Leucine Zipper 1 (bZIP1), a central integrator of metabolic signaling in plants. Using TARGET-tU, we captured newly synthesized mRNAs made in response to bZIP1 nuclear import at a time when bZIP1 is no longer detectably bound to its target. Thus, the analysis of de novo transcripomics demonstrates that bZIP1 may act as a catalyst TF to initiate a transcriptional complex (“hit”), after which active transcription by RNA polymerase continues without the TF being bound to the gene promoter (“run”). Our findings provide experimental proof for active transcription of transient TF-targets supporting a “hit-and-run” mode of action. This dynamic regulatory model allows a master TF to catalytically propagate rapid and broad transcriptional responses to changes in environment. Thus, the functional read-out of de novo transcripts produced by transient TF-target interactions allowed us to capture new models for genome-wide transcriptional control. The online version of this article (doi:10.1186/s12864-016-2410-2) contains supplementary material, which is available to authorized users.