Mechanism and functions of DALRD3-dependent tRNA modification

项目摘要 tRNA修饰酶中的许多遗传变异与 毁灭性的神经发育和神经系统疾病。然而，分子 支持这些病理的机制是未知的。为什么扰动 许多不同的tRNA修饰酶，从而改变了各种化学物质， 它们催化的改变，似乎比其他器官更能影响大脑？到 为了解决这个问题，我们的实验室试图阐明tRNA的分子和细胞作用 修饰酶在人类健康和疾病中的作用。我们最近发现了一本小说 tRNA合成酶样模拟物，DALRD3，其是特定化学修饰所需的 在人类tRNA的一个子集中。我们的初步结果表明，DALRD3依赖性 修饰影响tRNA构象稳定性和功能。值得注意的是，我们还 在DALRD3基因中发现了一种常染色体隐性变异， 功能和神经系统疾病癫痫性脑病。基于这些 研究结果，我们认为DALRD3介导的修饰在正确的细胞内起着关键作用。 在神经发育过程中对蛋白质合成重要的特定tRNA的功能。在 我们的第一个目标是定义tRNA识别和修饰的要求 依赖于DALRD3及其同源tRNA底物。我们的第二个目标是， 测量DALRD3依赖性修饰对tRNA结构和功能的影响。 在我们的最终目标中，我们将确定DALRD3依赖性tRNA修饰在细胞凋亡中的作用。 通过核糖体分析来研究大脑中的整体蛋白质翻译。总的来说， 这项研究将对理解tRNA修饰如何 影响正常的神经发育尽管DALRD3在tRNA中是一个意想不到的角色， 修改，我们现在有一个新的目标，探索潜在的治疗方法，为个人 患有与tRNA生物学有关的癫痫性脑病

PROJECT SUMMARY Numerous genetic variants in tRNA modification enzymes have been linked to devastating neurodevelopmental and neurological disorders. However, the molecular mechanisms underpinning these pathologies are unknown. Why is it that perturbations to many different tRNA modification enzymes and thus, changes to the various chemical modifications they catalyze, seem to affect the brain more so than other organs? To resolve this question, our lab seeks to elucidate the molecular and cellular roles of tRNA modification enzymes in human health and disease. We have recently uncovered a novel tRNA synthetase-like mimic, DALRD3, that is required for a specific chemical modification in a subset of human tRNAs. Our preliminary results suggest that the DALRD3-dependent modification impacts tRNA conformational stability and function. Notably, we have also identified an autosomal-recessive variant in the DALRD3 gene that causes loss of function and the neurological disorder epileptic encephalopathy. Based upon these findings, we propose that DALRD3-mediated modification plays a critical role in the proper function of specific tRNAs important for protein synthesis during neurodevelopment. In our first Aim, we will define the requirements for tRNA recognition and modification dependent in DALRD3 and its cognate tRNA substrates. For our second Aim, we will measure the impact of DALRD3-dependent modification on tRNA structure and function. In our final Aim, we will determine the role of DALRD3-dependent tRNA modification on global protein translation in the brain through ribosome profiling. In total, the proposed research will have broad implications in understanding how tRNA modifications can impact proper neurodevelopment. Although DALRD3 was an unexpected player in tRNA modification, we now have a new target to explore potential therapeutics for individuals suffering from epileptic encephalopathies linked to tRNA biology.