Phosphorylation of EIF2S1 (eukaryotic translation initiation factor 2 subunit alpha) is indispensable for nuclear translocation of TFEB and TFE3 during ER stress
Phosphorylation of EIF2S1 (eukaryotic translation initiation factor 2 subunit alpha) is indispensable for nuclear translocation of TFEB and TFE3 during ER stress
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DOI：
10.1080/15548627.2023.2173900
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发表时间：
2023-02-09
期刊：
影响因子：
13.3
通讯作者：
Back, Sung Hoon
中科院分区：
文献类型：
--
作者：
Dang, Thao Thi;Kim, Mi-Jeong;Back, Sung Hoon
在内质网应激条件下，巨噬/自噬途径与未折叠蛋白反应（UPR）途径之间存在多种联系，以恢复内质网稳态。EIF2S1/eIF2 α的磷酸化是一个重要的机制，它可以通过转录和翻译重编程来调节所有三种UPR途径，以维持细胞稳态和克服细胞应激。在这项研究中，为了研究EIF2S1磷酸化在内质网应激下调节自噬中的作用，我们使用了残基51从丝氨酸突变为丙氨酸的EIF2S1磷酸化缺陷（A/A）细胞。在内质网应激条件下，受自噬主转录因子TFEB和TFE3转录活性调控的A/A细胞在自噬过程的几个步骤（如自噬体和自噬体的形成）中表现出缺陷。在内质网胁迫下，TFEB和TFE3的核易位需要EIF2S1磷酸化。此外，EIF2AK3/PERK、PPP3/钙调磷酸酶介导的TFEB和TFE3的去磷酸化以及YWHA/14-3-3解离是其核易位所必需的，但不足以诱导内质网应激时的核保留。过表达活化的ATF6/ATF6 α形式、XBP1s和ATF4不同程度地挽救了内质网应激下A/A细胞中TFEB和TFE3核易位缺陷。因此，虽然XBP1s和ATF4在内质网应激下也显示出恢复A/A细胞自噬的能力，但活化的ATF6或TFEB的过表达更有效地形成了挽救的自噬缺陷。我们的研究结果表明，EIF2S1磷酸化在自噬和UPR通路中发挥重要作用，恢复内质网稳态，并揭示了EIF2S1磷酸化如何将UPR通路与自噬联系起来。
There are diverse links between macroautophagy/autophagy pathways and unfolded protein response (UPR) pathways under endoplasmic reticulum (ER) stress conditions to restore ER homeostasis. Phosphorylation of EIF2S1/eIF2 alpha is an important mechanism that can regulate all three UPR pathways through transcriptional and translational reprogramming to maintain cellular homeostasis and overcome cellular stresses. In this study, to investigate the roles of EIF2S1 phosphorylation in regulation of autophagy during ER stress, we used EIF2S1 phosphorylation-deficient (A/A) cells in which residue 51 was mutated from serine to alanine. A/A cells exhibited defects in several steps of autophagic processes (such as autophagosome and autolysosome formation) that are regulated by the transcriptional activities of the autophagy master transcription factors TFEB and TFE3 under ER stress conditions. EIF2S1 phosphorylation was required for nuclear translocation of TFEB and TFE3 during ER stress. In addition, EIF2AK3/PERK, PPP3/calcineurin-mediated dephosphorylation of TFEB and TFE3, and YWHA/14-3-3 dissociation were required for their nuclear translocation, but were insufficient to induce their nuclear retention during ER stress. Overexpression of the activated ATF6/ATF6 alpha form, XBP1s, and ATF4 differentially rescued defects of TFEB and TFE3 nuclear translocation in A/A cells during ER stress. Consequently, overexpression of the activated ATF6 or TFEB form more efficiently rescued autophagic defects, although XBP1s and ATF4 also displayed an ability to restore autophagy in A/A cells during ER stress. Our results suggest that EIF2S1 phosphorylation is important for autophagy and UPR pathways, to restore ER homeostasis and reveal how EIF2S1 phosphorylation connects UPR pathways to autophagy.