Department of Neurosurgical Engineering and Translational Neuroscience, Tohoku University Graduate School of Medicine, Sendai, Japan; Department of Neurosurgical Engineering and Translational Neuroscience, Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan; Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Japan.
Department of Biological Engineering and Center for Environmental Health Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA.
Neuroscience. 2022 Oct 1;501:103-130. doi: 10.1016/j.neuroscience.2022.08.009. Epub 2022 Aug 17.
Ferroptosis is a non-apoptotic cell death mechanism characterized by the generation of lipid peroxides. While many effectors in the ferroptosis pathway have been mapped, its epitranscriptional regulation is not yet fully understood. Ferroptosis can be induced via system xCT inhibition (Class I) or GPX4 inhibition (Class II). Previous works have revealed important differences in cellular response to different ferroptosis inducers. Importantly, blocking mRNA transcription or translation appears to protect cells against Class I ferroptosis inducing agents but not Class II. In this work, we examined the impact of blocking transcription (via Actinomycin D) or translation (via Cycloheximide) on Erastin (Class I) or RSL3 (Class II) induced ferroptosis. Blocking transcription or translation protected cells against Erastin but was detrimental against RSL3. Cycloheximide led to increased levels of GSH alone or when co-treated with Erastin via the activation of the reverse transsulfuration pathway. RNA sequencing analysis revealed early activation of a strong alternative splice program before observed changes in transcription. mRNA stability analysis revealed divergent mRNA stability changes in cellular response to Erastin or RSL3. Importantly, codon optimality biases were drastically different in either condition. Our data also implicated translation repression and rate as an important determinant of the cellular response to ferroptosis inducers. Given that mRNA stability and codon usage can be influenced via the tRNA epitranscriptome, we evaluated the role of a tRNA modifying enzyme in ferroptosis stress response. Alkbh1, a tRNA demethylase, led to translation repression and increased the resistance to Erastin but made cells more sensitive to RSL3.
铁死亡是一种非凋亡性的细胞死亡机制，其特征是脂质过氧化物的产生。虽然铁死亡途径中的许多效应物已经被定位，但它的转录后调控还不完全清楚。铁死亡可以通过系统 xCT 抑制（I 类）或 GPX4 抑制（II 类）来诱导。以前的工作揭示了细胞对不同铁死亡诱导剂的反应存在重要差异。重要的是，阻断 mRNA 转录或翻译似乎可以保护细胞免受 I 类铁死亡诱导剂的影响，但不能保护细胞免受 II 类铁死亡诱导剂的影响。在这项工作中，我们研究了阻断转录（通过放线菌素 D）或翻译（通过环己酰亚胺）对 Erastin（I 类）或 RSL3（II 类）诱导的铁死亡的影响。阻断转录或翻译可以保护细胞免受 Erastin 的影响，但对 RSL3 则有害。环己酰亚胺单独或与 Erastin 联合使用时，通过激活反硫化途径，导致 GSH 水平升高。RNA 测序分析显示，在观察到转录变化之前，早期就激活了一个强烈的替代剪接程序。mRNA 稳定性分析显示，细胞对 Erastin 或 RSL3 的反应存在不同的 mRNA 稳定性变化。重要的是，在这两种情况下，密码子优化偏差有很大的不同。我们的数据还表明，翻译抑制和速率是细胞对铁死亡诱导剂反应的一个重要决定因素。鉴于 mRNA 稳定性和密码子使用可以通过 tRNA 转录后修饰组来影响，我们评估了 tRNA 修饰酶在铁死亡应激反应中的作用。Alkbh1 是一种 tRNA 脱甲基酶，它导致翻译抑制，增加了对 Erastin 的抗性，但使细胞对 RSL3 更敏感。
