Epitranscriptomic control of ROS

GSH氧化还原循环的维持依赖于含硒半胱氨酸的GSH的活性 代谢酶在化学预防中发挥重要作用。硒代半胱氨酸是第21位 氨基酸并且不包含专用密码子。翻译过程中硒代半胱氨酸的掺入 需要UGA终止密码子重新编码，其使用特定修饰的tRNA进行准确解码。 tRNA修饰的动态变化是一种表观信号，因为它们调节基因的表达， 转录后表达。我们已经证明，许多压力诱导的翻译 含硒半胱氨酸的ROS解毒酶依赖于Alkbh 8 tRNA 甲基转移酶Alkbh 8酶促甲基化tRNA硒代半胱氨酸上的尿苷摆动碱基， 促进UGA终止密码子解码。我们已经开发了一种Alkbh 8缺陷型小鼠，并使用 分子、生物化学和基因组方法来证明Alkbh 8Def小鼠胚胎 成纤维细胞（MEF）和一些器官显示衰老标记和衰老基因标记。 使用人类细胞和我们的新Alkbh 8Def/p16- 3 MR小鼠，我们提出测试假设， 衰老发生在体外和体内，因为有缺陷的表转录组信号， 控制硒代半胱氨酸的利用。为了实现这两个目标，将：1。确定Alkbh 8和其他 限制硒代半胱氨酸利用的epitranscriptomic writers限制衰老程序，和2. 确定Alkbh 8缺陷是否在体内驱动衰老以及衰老消融是否加速 或缓和伴随硒蛋白损失的病理。我们的提案是与 重要的初步数据支持Alkbh 8和表转录组信号是 通过限制衰老活性进行化学预防。

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.