Dystonia 16 (DYT16) mutations in PACT cause dysregulated PKR activation and eIF2α signaling leading to a compromised stress response
Dystonia 16 (DYT16) mutations in PACT cause dysregulated PKR activation and eIF2α signaling leading to a compromised stress response
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DOI：
10.1016/j.nbd.2020.105135
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发表时间：
2020-12-01
影响因子：
6.1
通讯作者：
Patel, Rekha C.
中科院分区：
文献类型：
--
作者：
Burnett, Samuel B.;Vaughn, Lauren S.;Patel, Rekha C.
肌张力障碍16（DYT 16）是由干扰素诱导的双链RNA激活蛋白激酶（PKR）的蛋白激活剂PACT突变引起的。PKR通过翻译起始因子eIF 2 α的磷酸化调节整合应激反应（ISR）。这种翻译后修饰减弱了一般蛋白质合成，同时伴随触发了一些特定转录物的增强翻译，导致恢复和稳态或细胞凋亡，这取决于应激信号的强度和持续时间。PKR在决定细胞对病毒感染、氧化应激、内质网（ER）应激和生长因子剥夺的反应中起调节作用。在没有应激的情况下，PACT和PKR都被其抑制剂反式激活RNA结合蛋白（TRBP）结合，从而保持PKR失活。在细胞应激条件下，这些抑制性相互作用解离，促进PKR活化的关键PACT-PACT相互作用。虽然PACT-TRBP和PKR-TRBP相互作用都是促存活的，但PACT-PACT和PACT-PKR相互作用是促凋亡的。在这项研究中，我们评估了五个DYT 16取代突变是否改变PKR激活和ISR。我们的研究结果表明，突变体DYT 16蛋白表现出更强的PACT-PACT相互作用和增强的PKR激活。在DYT 16患者来源的淋巴母细胞中，增强的PACT-PKR相互作用和升高的PKR活化导致ISR失调和增加的细胞凋亡。更重要的是，这种增强的对ER应激的敏感性可以通过破坏PACT-PKR相互作用的毛地黄黄酮来拯救。我们的研究结果不仅证明了DYT 16突变对ISR和DYT 16病因学调节的影响，而且表明在进一步评估这些策略后，治疗干预是可能的。
Dystonia 16 (DYT16) is caused by mutations in PACT, the protein activator of interferon-induced double stranded RNA-activated protein kinase (PKR). PKR regulates the integrated stress response (ISR) via phosphorylation of the translation initiation factor eIF2 alpha. This post-translational modification attenuates general protein synthesis while concomitantly triggering enhanced translation of a few specific transcripts leading either to recovery and homeostasis or cellular apoptosis depending on the intensity and duration of stress signals. PKR plays a regulatory role in determining the cellular response to viral infections, oxidative stress, endoplasmic reticulum (ER) stress, and growth factor deprivation. In the absence of stress, both PACT and PKR are bound by their inhibitor transactivation RNA-binding protein (TRBP) thereby keeping PKR inactive. Under conditions of cellular stress these inhibitory interactions dissociate facilitating PACT-PACT interactions critical for PKR activation. While both PACT-TRBP and PKR-TRBP interactions are pro-survival, PACT-PACT and PACT-PKR interactions are pro-apoptotic. In this study we evaluate if five DYT16 substitution mutations alter PKR activation and ISR. Our results indicate that the mutant DYT16 proteins show stronger PACT-PACT interactions and enhanced PKR activation. In DYT16 patient derived lymphoblasts the enhanced PACT-PKR interactions and heightened PKR activation leads to a dysregulation of ISR and increased apoptosis. More importantly, this enhanced sensitivity to ER stress can be rescued by luteolin, which disrupts PACT-PKR interactions. Our results not only demonstrate the impact of DYT16 mutations on regulation of ISR and DYT16 etiology but indicate that therapeutic interventions could be possible after a further evaluation of such strategies.