Epitranscriptomic control of ROS

谷胱甘肽氧化还原循环的维持依赖于含硒半胱氨酸的谷胱甘肽的活性 在化学预防中起基础作用的代谢酶。硒半胱氨酸是第21位 氨基酸，不含专用密码子。硒半胱氨酸在翻译过程中的掺入 需要UGA-停止密码子重新编码，它使用专门修改的tRNA进行准确解码。 TRNA修饰的动态变化是一种表位转录信号，因为它们调节基因 转录后表达。我们已经证明，应激诱导的许多翻译 含硒半胱氨酸的ROS解毒酶依赖于Alkbh8 tRNA 甲基转移酶。Alkbh8酶法甲基化tRNAs半胱氨酸的尿苷摆动碱基以 推广UGA--停止密码子解码。我们已经开发了一种Alkbh8缺陷小鼠，并使用了 证明Alkbh8Def小鼠胚胎的分子、生化和基因组方法 成纤维细胞(MEF)和一些器官显示衰老的标志和衰老的基因特征。 使用人类细胞和我们新的Alkbh8Def/p16-3MR小鼠，我们建议检验这一假设 衰老发生在体外和体内，因为有缺陷的表位转录信号 控制硒半胱氨酸的利用。为了实现这一目标，将有两个目标：1.确定Alkbh8和其他 限制硒半胱氨酸利用的表位转录作家限制衰老计划和2. 确定体内Alkbh8缺乏是否导致衰老，以及衰老消融是否加速 或缓和伴随硒蛋白丢失而来的病理。我们的提案正在提交中 重要的初步数据支持Alkbh8和表位转录信号是 通过限制衰老活动来进行化学预防。

Maintenance of the GSH redox cycle is reliant on the activities of selenocysteine-containing GSH metabolizing enzymes which play fundamental roles in chemoprevention. Selenocysteine is the 21st amino acid and does not contain a dedicated codon. Selenocysteine incorporation during translation requires UGA-stop-codon recoding, which uses specifically modified tRNA for accurate decoding. Dynamic changes in tRNA modification are an epitranscriptomic signal because they regulate gene expression post-transcriptionally. We have shown that the stress-induced translation of many selenocysteine containing ROS detoxifying enzymes is dependent on the Alkbh8 tRNA methyltransferase. Alkbh8 enzymatically methylates the uridine wobble base on tRNASelenocysteine to promote UGA-stop codon decoding. We have developed an Alkbh8 deficient mouse and have used molecular, biochemical, and genomic approaches to demonstrate that Alkbh8Def mouse embryonic fibroblasts (MEFs) and some organs display markers of senescence and a senescence gene signature. Using human cells and our new Alkbh8Def/p16-3MR mice we propose to test the hypothesis that senescence occurs in vitro and in vivo because of defective epitranscriptomic signals that controls selenocysteine utilization. To achieve this, two aims will: 1. determine if Alkbh8 and other epitranscriptomic writers that limit selenocysteine utilization restrict the senescence program and 2. determine if Alkbh8-deficiency drives senescence in vivo and whether senescence ablation accelerates or tempers pathologies that accompany selenoprotein loss. Our proposal is being submitted with significant preliminary data supporting the idea that Alkbh8 and epitranscriptomic signals are key to chemoprevention by limiting senescent activity.