Overcoming the cytoplasmic retention of GDOWN1 modulates global transcription and facilitates stress adaptation.
Overcoming the cytoplasmic retention of GDOWN1 modulates global transcription and facilitates stress adaptation.
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DOI：
10.7554/elife.79116
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发表时间：
2022-12-07
期刊：
影响因子：
7.7
通讯作者：
Cheng B
中科院分区：
文献类型：
--
作者：
Zhu Z;Liu J;Feng H;Zhang Y;Huang R;Pan Q;Nan J;Miao R;Cheng B
转录的动态调节对于细胞对各种环境或发育线索的反应至关重要。Gdown 1是一种广泛表达的RNA聚合酶II（Pol II）相互作用蛋白，对后生动物的胚胎发育至关重要。它在体外与Pol II紧密结合，并竞争性地阻断TFIIF和可能的其他转录调节因子的结合，但其细胞功能和调节回路仍不清楚。在这里，我们表明，人GDOWN1严格定位于各种类型的体细胞的细胞质中，并表现出强有力的抵抗力，其核定位的强加的驱动力。结合遗传学和显微镜的方法，我们发现了两类功能上偶联的、进化上保守的定位调控基序，包括CRM1依赖的核输出信号（内斯）和一种新的胞质转运信号（CAS），它介导CRM1在核孔复合物（NPC）外的滞留。CAS的突变增强了GDOWN1的细胞质滞留，从而解锁了其核质穿梭特性，并且GDOWN1的核输入和积累增加导致Pol II及其相关的全局转录水平急剧降低。重要的是，GDOWN1的核转位发生在对氧化应激的响应中，并且GDOWN1的消融显著削弱了细胞耐受性。总的来说，我们的工作揭示了GDOWN1的亚细胞定位的分子基础和一种新的细胞策略，通过控制GDOWN1的核转位来调节全局转录和应激适应。
Dynamic regulation of transcription is crucial for the cellular responses to various environmental or developmental cues. Gdown1 is a ubiquitously expressed, RNA polymerase II (Pol II) interacting protein, essential for the embryonic development of metazoan. It tightly binds Pol II in vitro and competitively blocks the binding of TFIIF and possibly other transcriptional regulatory factors, yet its cellular functions and regulatory circuits remain unclear. Here, we show that human GDOWN1 strictly localizes in the cytoplasm of various types of somatic cells and exhibits a potent resistance to the imposed driving force for its nuclear localization. Combined with the genetic and microscope-based approaches, two types of the functionally coupled and evolutionally conserved localization regulatory motifs are identified, including the CRM1-dependent nucleus export signal (NES) and a novel Cytoplasmic Anchoring Signal (CAS) that mediates its retention outside of the nuclear pore complexes (NPC). Mutagenesis of CAS alleviates GDOWN1’s cytoplasmic retention, thus unlocks its nucleocytoplasmic shuttling properties, and the increased nuclear import and accumulation of GDOWN1 results in a drastic reduction of both Pol II and its associated global transcription levels. Importantly, the nuclear translocation of GDOWN1 occurs in response to the oxidative stresses, and the ablation of GDOWN1 significantly weakens the cellular tolerance. Collectively, our work uncovers the molecular basis of GDOWN1’s subcellular localization and a novel cellular strategy of modulating global transcription and stress-adaptation via controlling the nuclear translocation of GDOWN1.