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

描述(申请人提供)：氨基酰-tRNA合成酶在疾病中的翻译外作用摘要：我的目标是了解甘氨酰-tRNA合成酶(GlyRS)的扩展功能以及它们如何与Charcot-Marie-Tooth(CMT)疾病联系起来。GlyRS是氨基酰-tRNA合成酶(AARS)家族的20个成员之一，在蛋白质合成的第一步催化转移tRNA的氨基酰化。GARS(GlyRS基因)和YARS(酪氨酸氨基-tRNA合成酶基因)的显性突变已在人群中被发现，可导致Charcot-Marie-Tooth(CMT)病。CMT病也称为遗传性运动神经病和感觉神经病，是最常见的遗传性周围神经病，发病率约为1/2500人。CMT表型不是由于必需的氨基酰化功能降低引起的。这一观察结果导致了我们的假设，即这两种tRNA合成酶已经扩展了功能(超越了氨基酰化)，这对于理解它们与CMT的联系至关重要。该提案的重点是GlyRS。对GlyRS相互作用伙伴的搜索发现了Daxx，一种与Fas的细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的一员，Fas-Daxx相互作用促进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，我们发现一种修饰形式的GlyRS与Daxx特异地相互作用。我们已经确定GlyRS的修饰物是一种名为NEDD8的泛素样蛋白。已知NEDD化可以调节其底物的功能。有趣的是，NEDD8上与底物结合的残基是C-末端甘氨酸，它在泛素和几乎所有的泛素样蛋白中都是保守的。NEDD化的第一个反应是C端甘氨酸与三磷酸腺苷缩合的腺基化反应。该反应在化学上与GlyRS催化氨基酰化反应的第一步反应相同。基于这种考虑，我们提出GlyRS参与Daxx的NEDD化，进而调节Daxx介导的细胞凋亡。事实上，我们发现与GlyRS相关的Daxx是NEDDylated的。因此，这里提出的工作将促进对AARS翻译外作用及其与人类疾病可能联系的理解。 公共卫生相关性：叙述该项目将有助于理解tRNA合成酶如何与最常见的遗传性神经病--夏科-玛丽-图斯病相关。我们在这项研究中获得的知识也将有助于了解其他神经系统疾病，如肌萎缩侧索硬化症(Lou Gehrig病)和帕金森病。

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. PUBLIC HEALTH RELEVANCE: Narrative This project will aid in understanding how tRNA synthetases function in connection to Charcot-Marie-Tooth disease, which is the most common hereditary neuropathy. The knowledge we gain in this study will also shed light on other neurological diseases such as Amyotrophic Lateral Sclerosis (Lou Gehrig's disease) and Parkinson's disease.