Studies of Aminoacyl-tRNA Synthetase Mutations Causing Progressive Microcephaly

项目摘要 小头畸形是指一种神经发育状况，头部尺寸小于预期， 在美国，每1,000个新生儿中就有一个。严重的进行性小头畸形也是 伴有神经变性和癫痫发作。最近的研究表明， 氨酰-tRNA合成酶是蛋白质合成所必需的一组酶， 小头畸形这些突变如何导致细胞毒性和中枢神经系统紊乱仍然是 待定义。我们以前的工作已经确定了致病突变的β-氨基-（QARS）和丙氨酰- （阿尔斯）tRNA合成酶在小头畸形患者，并表明这种突变导致这两个减少 氨酰化效率和蛋白质错误折叠。我们还发现了一个新的候选基因， 进行性小头畸形，其为乙酰化-（WARS）tRNA合成酶。在拟议的工作中，我们将 产生患者来源的淋巴母细胞和诱导多能干细胞系，以及酵母和神经元干细胞系， 携带致病突变的细胞系。由此产生的细胞将用于确定：（1）QARS的影响 突变对蛋白质合成和细胞毒性的影响;（2）氨酰化和编辑缺陷对蛋白质合成和细胞毒性的影响。 阿尔斯;和（3）与小头畸形相关的WARS和丝氨酰-tRNA合成酶突变对 氨酰化和蛋白质错误折叠。这项工作将揭示缺陷蛋白质合成的细胞毒性 并为小头畸形的遗传原因提供了新的见解。本研究中开发的各种细胞系将 对今后蛋白质合成缺陷和蛋白质合成质量机理的研究也有一定的参考价值 控制

PROJECT SUMMARY Microcephaly refers to a neurodevelopmental condition with smaller than expected head size and affects approximately 1 in 1,000 new born babies in the United States. Severe progressive microcephaly is also accompanied with neurodegeneration and seizures. Recent studies reveal that recessive mutations in aminoacyl-tRNA synthetases, a group of essential enzymes required for protein synthesis, cause progressive microcephaly. How such mutations lead to cellular toxicity and disorder of the central nervous system remains to be defined. Our previous work has identified disease-causing mutations in glutaminyl- (QARS) and alanyl- (AARS) tRNA synthetases in microcephaly patients, and suggests that such mutations lead to both decreased aminoacylation efficiency and protein misfolding. We have also identified a novel candidate gene causing progressive microcephaly, which tryptophanyl- (WARS) tRNA synthetases. In the proposed work, we will generate patient-derived lymphoblastoid and induced pluripotent stem cell lines, as well as yeast and neuronal cell lines carrying pathogenic mutations. The resulting cells will be used to determine: (1) the impact of QARS mutations on protein synthesis and cellular toxicity; (2) the impact of aminoacylation and editing defects in AARS; and (3) the effects of mutations in WARS and seryl-tRNA synthetase associated with microcephaly on aminoacylation and protein misfolding. This work will reveal the cellular toxicity of defective protein synthesis and provide insights into the genetic causes of microcephaly. The various cell lines developed in this study will also be valuable for future studies of protein synthesis defects and the mechanism of protein synthesis quality control.