Defining the Role of Cysteinyl-tRNA Synthetase Variants in Neurological Disease

摘要 作为一名医生兼科学家，我的长期目标是研究神经遗传性疾病的分子机制， 最终目的是开发治疗方法。氨酰-tRNA合成酶（ARS）是必需的酶， 用同源氨基酸装载tRNA。到目前为止，37个编码ARS的基因座中有33个基因的突变已经被发现。 与显性周围神经病变或隐性多系统疾病有关;然而， ARS相关表型的基因座异质性是不完全的， ARS突变的后果知之甚少。半胱氨酰-tRNA合成酶（汽车）编码 在细胞质中用半胱氨酸装载tRNACYS的酶。到目前为止，汽车变体还没有被 与任何人类疾病表型有关。我们与NIH未诊断疾病项目合作， 从三个家庭中确定了四名患有复杂综合征的患者，包括小头畸形，发育障碍， 延迟和轴突周围神经病变;每个患者携带双等位基因汽车变体。临床和遗传 证据支持汽车突变致病性，蛋白表达研究和酵母 互补测定表明，每种汽车变体引起功能丧失效应。虽然损失- 功能分子病理学对于隐性疾病相关的ARS变体是共同的，下游的 对细胞、组织和生物体功能的影响尚不明确。此外，汽车变体在 尚未探索显性疾病。研究汽车变异体在隐性和显性遗传中的作用， 神经系统疾病，我们将：（1）研究与隐性疾病有关的患者突变对 在大脑中的蛋白质翻译;和（2）在汽车中产生功能丧失突变，并研究 潜在显性神经毒性。本研究为深入了解汽车的致病机制提供了理论依据 变异，揭示了潜在的治疗靶点，并扩大了ARS的临床和基因座异质性。 相关疾病。重要的是，这个项目将使我发展必要的研究生涯的技能 专注于了解人类遗传性疾病的机制。

ABSTRACT My long-term goal as a physician-scientist is to study the molecular mechanisms of neurogenetic disorders, with the ultimate aim of developing therapies. Aminoacyl-tRNA synthetases (ARSs) are essential enzymes that charge tRNA with cognate amino acids. To date, mutations in 33 of the 37 ARS-encoding loci have been implicated in dominant peripheral neuropathies or recessive multi-system disorders; however, the allelic and locus heterogeneity of ARS-related phenotypes is incomplete, and the molecular, cellular, and organismal consequences of ARS mutations are poorly understood. Cysteinyl-tRNA synthetase (CARS) encodes the enzyme that charges tRNACYS with cysteine in the cytoplasm. To date, CARS variants have not been implicated in any human disease phenotype. In collaboration with the NIH Undiagnosed Diseases Program, we identified four patients from three families with a complex syndrome that includes microcephaly, developmental delay, and axonal peripheral neuropathy; each patient carries bi-allelic CARS variants. Clinical and genetic evidence are supportive of CARS mutation pathogenicity, and protein expression studies and yeast complementation assays indicate that each CARS variant causes a loss-of-function effect. While a loss-of- function molecular pathology is common to recessive disease-associated ARS variants, the downstream effects on cellular, tissue, and organism function are poorly defined. Additionally, the role of CARS variants in dominant disease has not been explored. To investigate the role of CARS variants in recessive and dominant neurological disease, we will: (1) study the effect of patient mutations implicated in recessive disease on protein translation in the brain; and (2) generate loss-of-function mutations in CARS and investigate the potential for dominant neurotoxicity. This work will provide insight into the pathogenic mechanism of CARS variants, reveal potential therapeutic targets, and expand the clinical and locus heterogeneity of ARS- associated disease. Importantly, this project will allow me to develop the skills necessary for a research career focused on understanding the mechanisms of human inherited disease.