Functional analyses of glycyl-tRNA synthetase mutations suggest a key role for tRNA-charging enzymes in peripheral axons
Functional analyses of glycyl-tRNA synthetase mutations suggest a key role for tRNA-charging enzymes in peripheral axons
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DOI：
10.1523/jneurosci.1671-06.2006
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发表时间：
2006-10-11
影响因子：
5.3
通讯作者：
Green, Eric D.
中科院分区：
文献类型：
--
作者：
Antonellis, Anthony;Lee-Lin, Shih-Queen;Green, Eric D.
腓骨肌萎缩症2D型（CMT 2D）和远端脊髓性肌萎缩症V型（dSMA-V）是轴突神经病，其特征是上肢的表型更严重。我们先前认为编码甘氨酰-tRNA合成酶（加尔斯）的基因突变是导致CMT 2D和dSMA-V的原因。加尔斯是氨酰-tRNA合成酶家族的成员，负责用同源氨基酸装载tRNA;加尔斯将甘氨酸连接到tRNAGly。在这里，我们提出了与疾病相关的加尔斯突变的功能分析，并表明，有没有任何显着的突变相关的变化，加尔斯表达水平，大多数已确定的加尔斯突变酵母建模严重损害生存能力，并在大多数情况下，突变的加尔斯蛋白在神经元细胞中的错误定位。事实上，研究的五种突变中有四种在至少一种测定中显示出功能丧失的特征，表明tRNA充电缺陷在疾病发病机制中起作用。最后，我们在培养神经元的神经突投射和正常人体组织的周围神经轴突中检测到了内源性GARS相关颗粒。鉴于最近在另一种tRNA合成酶基因[YARS（酪氨酰-tRNA合成酶基因）]中鉴定出CMT相关突变，这些数据尤其重要。总之，这些发现表明，tRNA充电酶在维持外周轴突中起着关键作用。
Charcot-Marie-Tooth disease type 2D (CMT2D) and distal spinal muscular atrophy type V (dSMA-V) are axonal neuropathies characterized by a phenotype that is more severe in the upper extremities. We previously implicated mutations in the gene encoding glycyl-tRNA synthetase (GARS) as the cause of CMT2D and dSMA-V. GARS is a member of the family of aminoacyl-tRNA synthetases responsible for charging tRNA with cognate amino acids; GARS ligates glycine to tRNAGly. Here, we present functional analyses of disease-associated GARS mutations and show that there are not any significant mutation-associated changes in GARS expression levels; that the majority of identified GARS mutations modeled in yeast severely impair viability; and that, in most cases, mutant GARS protein mislocalizes in neuronal cells. Indeed, four of the five mutations studied show loss-of-function features in at least one assay, suggesting that tRNA-charging deficits play a role in disease pathogenesis. Finally, we detected endogenous GARS-associated granules in the neurite projections of cultured neurons and in the peripheral nerve axons of normal human tissue. These data are particularly important in light of the recent identification of CMT-associated mutations in another tRNA synthetase gene [YARS(tyrosyl-tRNA synthetase gene)]. Together, these findings suggest that tRNA-charging enzymes play a key role in maintaining peripheral axons.