Extra-translational roles of aminoacyl tRNA synthetases in connection to disease

描述（由申请人提供）：翻译外作用的氨酰-tRNA合成酶在连接到疾病摘要：我的目标是了解扩展功能的甘氨酰-tRNA合成酶（GlyRS），以及它们如何与腓骨肌萎缩症（CMT）疾病。GlyRS是氨酰-tRNA合成酶（阿尔斯）家族的20个成员之一，其在蛋白质合成的第一步中催化转移tRNA的氨酰化。已在人群中鉴定出加尔斯（GlyRS基因）和YARS（酪氨酰-tRNA合成酶基因）的显性突变导致腓骨肌萎缩症（CMT）。CMT疾病也称为遗传性运动和感觉神经病，是最常见的遗传性周围神经病，发生频率约为1/2500。CMT表型不是由必需的氨酰化功能降低引起的。这一观察结果导致我们假设这两种tRNA合成酶具有扩展的功能（超越氨酰化），这对于理解它们与CMT的联系至关重要。该提案的重点是GlyRS。寻找GlyRS的相互作用伙伴确定了Daxx，一种与Fas胞质结构域相互作用的蛋白质。Fas是肿瘤坏死因子受体超家族成员之一，Fas与Daxx相互作用增强Fas介导的细胞凋亡。值得注意的是，Fas-Daxx通路与CMT以及包括肌萎缩性侧索硬化症和帕金森病在内的许多其他神经系统疾病有关。这些考虑提出了GlyRS和Daxx之间的相互作用与CMT致病机制相关的可能性。令人惊讶的是，我们发现GlyRS的修饰形式与Daxx特异性相互作用。我们已经确定GlyRS的修饰物是一种叫做NEDD 8的泛素样蛋白。已知NEDD化调节其底物的功能。有趣的是，NEDD 8上用于与底物缀合的残基是C-末端甘氨酸，其在泛素和几乎所有泛素样蛋白中是保守的。NEDD化的第一个反应是C-末端甘氨酸与ATP缩合的腺苷酸化.它在化学上与氨基酰化中GlyRS催化的第一步反应相同。这种考虑使我们提出GlyRS参与Daxx的NEDD化，这反过来又调节Daxx介导的细胞凋亡。事实上，我们发现GlyRS相关的Daxx是NEDDylated的。因此，这里提出的工作将促进理解的翻译外作用的阿尔斯和他们可能的连接到人类疾病。

DESCRIPTION (provided by applicant): Extra-translational role of aminoacyl-tRNA synthetases in connection to disease Abstract: My goal is to understand the expanded functions of glycyl-tRNA synthetase (GlyRS) and how they connect with Charcot-Marie-Tooth (CMT) diseases. GlyRS is one of 20 members of the aminoacyl-tRNA synthetase (AARS) family that catalyzes aminoacylation of transfer tRNAin the first step of protein synthesis. Dominant mutations of GARS (gene for GlyRS) and YARS (gene for tyrosyl-tRNA synthetase) have been identified in the human population to cause Charcot-Marie-Tooth (CMT) diseases. Also known as hereditary motor and sensory neuropathies, CMT diseases are the most common heritable peripheral neuropathy, occurring with a frequency of approximately 1 in 2500 individuals. The CMT phenotype does not arise from a reduction in the essential aminoacylation function. This observation led to our hypothesis that these two tRNA synthetases have expanded functions (beyond aminoacylation) that are critical to understanding their connection to CMT. The focus of the proposal is on GlyRS. A search for interaction partners of GlyRS identified Daxx, a protein that interacts with the cytoplasmic domain of Fas. Fas is a member of the tumor necrosis factor receptor superfamily, and the Fas-Daxx interaction enhances Fas-mediated apoptosis. Significantly, The Fas-Daxx pathway is implicated in CMT, as well as in many other neurological disorders including Amyotrophic Lateral Sclerosis and Parkinson's disease. These considerations raised the possibility that the interaction between GlyRS and Daxx is relevant to the CMT disease-causing mechanism. Surprisingly, we found that a modified form of GlyRS specifically interacts with Daxx. We have identified the modifier of GlyRS to be a ubiquitin-like protein called NEDD8. NEDDylation is known to regulate the function of its substrates. Interestingly, the residue on NEDD8 for conjugation to substrate is the C-terminal glycine, which is conserved in ubiquitin and in almost all ubiquitin-like proteins. The first reaction in NEDDylation is the adenylation of the C- terminal glycine by condensation with ATP. It is chemically the same reaction as the first step of catalysis by GlyRS in aminoacylation. This consideration led us to propose that GlyRS is involved in the NEDDylation of Daxx which, in turn, regulates Daxx-mediated apoptosis. Indeed, we found that GlyRS-associated Daxx is NEDDylated. Thus, the work proposed here will advance understanding of the extra-translational roles of AARS and their possible connection to human disease.