CDK7 is a component of the integrated stress response regulating SNAT2 (SLC38A2)/System A adaptation in response to cellular amino acid deprivation.
CDK7 is a component of the integrated stress response regulating SNAT2 (SLC38A2)/System A adaptation in response to cellular amino acid deprivation.
复制标题
CDK7 是调节 SNAT2 (SLC38A2)/系统 A 适应以响应细胞氨基酸剥夺的综合应激反应的一个组成部分。
DOI：
10.1016/j.bbamcr.2019.03.002
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Stretton C
中科院分区：
文献类型：
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作者：
Stretton C
细胞外氨基酸(AA)的退出/限制引起一种整合的应激反应(ISR)，导致蛋白质合成的全球抑制，同时允许一组特定基因的转录和翻译，这些基因的蛋白质产物促进细胞对AA不足的适应。系统A/SNAT2 AA转运体的转录诱导是一种经典的适应反应，关键依赖于一般控制不可降压-2激酶/激活转录因子4(GCN2/ATF4)通路的激活。然而，ISR还可以包括结合或独立于GCN2/ATF4操作以上调SNAT2的附加信令输入。在这里，我们表明，虽然药物抑制MEK-ERK，mTORC1和p38 MAP激酶信号对系统A的上调没有可检测到的影响，但针对GSK3的抑制剂(例如SB415286)导致了对SNAT2适应反应的显著抑制。值得注意的是，在Gsk3α/β稳定沉默的细胞中，SB415286的作用持续存在，这表明了一种脱靶效应。我们发现SB415286也能抑制细胞周期蛋白依赖性激酶(CDK)，而罗索维汀和黄烷醇(两种PAN CDK抑制剂)是SNAT2适应性反应的有效阻滞剂。特别是，我们的工作揭示了CDK7活性在AA剥夺的细胞中以GCN-2依赖的方式上调，并且有效和选择性的CDK7抑制剂THz-1不仅减弱了ATF4表达的增加，而且阻止了系统A的适应。重要的是，在表达多西环素可诱导的耐药形式的CDK7的细胞中，THz-1对系统A适应的抑制效应得到缓解。我们的数据证明CDK7是ISR调节系统A适应AA不足的一个新组件。
Extracellular amino acid (AA) withdrawal/restriction invokes an integrated stress response (ISR) that induces global suppression of protein synthesis whilst allowing transcription and translation of a select group of genes, whose protein products facilitate cellular adaptation to AA insufficiency. Transcriptional induction of the System A/SNAT2 AA transporter represents a classic adaptation response and crucially depends upon activation of the General Control Nonderepressible-2 kinase/Activating transcription factor 4 (GCN2/ATF4) pathway. However, the ISR may also include additional signalling inputs operating in conjunction or independently of GCN2/ATF4 to upregulate SNAT2. Herein, we show that whilst pharmacological inhibition of MEK-ERK, mTORC1 and p38 MAP kinase signalling has no detectable effect on System A upregulation, inhibitors targeting GSK3 (e.g.SB415286) caused significant repression of the SNAT2 adaptation response. Strikingly, the effects of SB415286 persist in cells in which GSK3α/β have been stably silenced indicating an off-target effect. We show that SB415286 can also inhibit cyclin-dependent kinases (CDK) and that roscovitine and flavopiridol (two pan CDK inhibitors) are effective repressors of the SNAT2 adaptive response. In particular, our work reveals that CDK7 activity is upregulated in AA-deprived cells in a GCN-2-dependent manner and that a potent and selective CDK7 inhibitor, THZ-1, not only attenuates the increase in ATF4 expression but blocks System A adaptation. Importantly, the inhibitory effects of THZ-1 on System A adaptation are mitigated in cells expressing a doxycycline-inducible drug-resistant form of CDK7. Our data identify CDK7 as a novel component of the ISR regulating System A adaptation in response to AA insufficiency.