TUBA1A mutations identified in lissencephaly patients dominantly disrupt neuronal migration and impair dynein activity
TUBA1A mutations identified in lissencephaly patients dominantly disrupt neuronal migration and impair dynein activity
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DOI：
10.1093/hmg/ddy416
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发表时间：
2019-04-15
影响因子：
3.5
通讯作者：
Bates, Emily A.
中科院分区：
文献类型：
--
作者：
Aiken, Jayne;Moore, Jeffrey K.;Bates, Emily A.
微管细胞骨架在脑发育过程中支持不同的细胞形态发生和迁移过程。微管蛋白基因的突变与严重的人类大脑畸形（称为“微管蛋白病”）有关;然而，微管亚基的分子水平变化如何导致大脑畸形尚不清楚。在这项研究中，我们证明错义突变影响精氨酸在位置402（R402）TUBA 1A α-微管蛋白选择性损害动力蛋白运动活性，严重和占主导地位的破坏皮质神经元迁移。TUBA 1A是微管蛋白病患者中最常见的微管蛋白基因，改变R402的突变占所有报告的TUBA 1A突变的30%。我们首次表明TUBA 1A-R402 C和TUBA 1A-R402 H患者等位基因的异位表达足以显性破坏发育中小鼠大脑中的皮质神经元迁移，强烈支持脑畸形病理学中的因果作用。为了分离R402突变的精确分子影响，我们在芽殖酵母α-微管蛋白中产生了类似的R402 C和R402 H突变，其表现出简化的微管细胞骨架。我们发现，R402突变微管组装成微管，支持正常的驱动蛋白电机活动，但不能支持动力蛋白电机的活动。重要的是，动力蛋白损伤的水平与细胞中突变体的表达水平成比例，这表明了一种“中毒”机制，其中R402突变体α-微管蛋白主要通过使微管与动力蛋白的缺陷结合位点共存而起作用。基于我们的研究结果，我们提出了一种新的微管蛋白病的分子病理学模型，也可能扩展到其他微管蛋白相关的神经病变。
The microtubule cytoskeleton supports diverse cellular morphogenesis and migration processes during brain development. Mutations in tubulin genes are associated with severe human brain malformations known as 'tubulinopathies'; however, it is not understood how molecular-level changes in microtubule subunits lead to brain malformations. In this study, we demonstrate that missense mutations affecting arginine at position 402 (R402) of TUBA1A alpha-tubulin selectively impair dynein motor activity and severely and dominantly disrupt cortical neuronal migration. TUBA1A is the most commonly affected tubulin gene in tubulinopathy patients, and mutations altering R402 account for 30% of all reported TUBA1A mutations. We show for the first time that ectopic expression of TUBA1A-R402C and TUBA1A-R402H patient alleles is sufficient to dominantly disrupt cortical neuronal migration in the developing mouse brain, strongly supporting a causal role in the pathology of brain malformation. To isolate the precise molecular impact of R402 mutations, we generated analogous R402C and R402H mutations in budding yeast alpha-tubulin, which exhibit a simplified microtubule cytoskeleton. We find that R402 mutant tubulins assemble into microtubules that support normal kinesin motor activity but fail to support the activity of dynein motors. Importantly, the level of dynein impairment scales with the expression level of the mutant in the cell, suggesting a 'poisoning' mechanism in which R402 mutant alpha-tubulin acts dominantly by populating microtubules with defective binding sites for dynein. Based on our results, we propose a new model for the molecular pathology of tubulinopathies that may also extend to other tubulin-related neuropathies.