Senataxin mutations in familial motor neuron disease (ALS4) and Ataxia (AOA2)

描述（由申请人提供）：我们发现Senataxin基因（SETX）突变是家族性肌萎缩侧索硬化症（ALS）幼年发病、常染色体显性（AD）形式的分子基础。这种形式的ALS，称为ALS 4，是一种基本上纯运动系统障碍，其特征在于肢体无力，严重的肌肉萎缩，锥体束征和缓慢的疾病进展。有趣的是，SETX的隐性突变会导致第二种疾病，一种称为共济失调-眼动性失用症2型（AOA 2）的共济失调。在AOA 2中，发病率也很高，在发病后约15-20年（通常在10-22岁之间）发生脱发。这些发现共同证明了SETX突变的基因型-表型相关性，并证实senataxin是一种重要的神经元蛋白。Senataxin是一种由2677个氨基酸组成的大蛋白质，其确切功能在很大程度上是未知的。它含有一个保守的DNA/RNA解旋酶结构域，朝向C-末端，表明在RNA加工中的功能。这种重要的RNA加工功能已被表征为酵母直向同源物Sen 1 p。在酵母中的研究也支持在极端N-末端中也存在潜在的蛋白质-蛋白质相互作用结构域。我们的研究将集中在与ALS 4和AOA 2相关的Senataxin的突变形式上，并解决以下广泛的目标：（1）我们将表征我们为ALS 4产生的鼠基因靶向和转基因（Tg）模型，并测试它们是否发展神经病，从而允许进一步详细研究神经元变性途径;（2）使用基因捕获技术，我们将开发AOA 2的鼠敲除模型;（3）我们假设ALS 4突变体Senataxin（L389 S）可能导致毒性功能获得，例如异常的蛋白质-蛋白质相互作用。为了测试这一点，我们进行了酵母双杂交（Y2 H）筛选野生型和ALS 4突变N-末端senataxin的人脑表达文库。我们确定了ALS 4与驱动蛋白KIF 1B的特异性相互作用，并通过进一步的Y2 H重新测试和哺乳动物2-H测定进行了验证。我们将进一步研究这种相互作用及其在ALS 4中的潜在致病作用。公共卫生相关性：从这项研究中获得的潜在知识是对家族性ALS和共济失调中神经元死亡原因的进一步了解。作为研究的一部分，正在开发的小鼠模型也可能被证明非常有用，最终将与其他感兴趣的研究人员共享。由于目前没有治愈或预防性治疗这些疾病，任何获得的知识都有可能为这些患者提供未来的诊断和治疗干预措施。

DESCRIPTION (provided by applicant): We discovered mutations in the Senataxin gene (SETX) as the molecular basis of a juvenile-onset, autosomal dominant (AD) form of familial amyotrophic lateral sclerosis (ALS). This form of ALS, known as ALS4, is an essentially pure motor systems disorder characterized by limb weakness, severe muscle wasting, pyramidal signs, and slow disease progression. Intriguingly, recessive mutations of SETX cause a second disease, a form of ataxia known as Ataxia-Oculomotor Apraxia type 2 (AOA2). In AOA2, morbidity is also high with loss of ambulation occurring ~15-20 years following onset which normally ranges from 10-22 years of age. Together these findings demonstrate genotype-phenotype correlation for SETX mutations and confirm senataxin as an important neuronal protein. Senataxin is a large protein at 2677 amino acids and its precise function is largely unknown. It contains a conserved DNA/RNA helicase domain towards the C-terminal suggesting a function in RNA processing. Such important RNA processing functions have been characterized for the yeast orthologue, Sen1p. There is also a potential protein-protein interaction domain in the extreme N-terminal which is supported by studies in yeast. Our studies will focus on mutant forms of Senataxin associated with ALS4 and AOA2 and address the following broad aims: (1) We will characterize murine gene targeted and transgenic (Tg) models we have produced for ALS4 and test if they develop neuropathies allowing further detailed study of neuronal degeneration pathways; (2) Using gene trap technology we will develop a murine knock-out model for AOA2; and (3) we have hypothesized that ALS4 mutant Senataxin (L389S) may lead to toxic gain-of-function such as aberrant protein-protein interaction. To test this we undertook yeast two-hybrid (Y2H) screens with wt and ALS4 mutant N-terminal senataxin of a human brain expression library. We identified a ALS4 specific interaction with the kinesin, KIF1B, that was validated with further Y2H re-testing and mammalian 2-H assays. We will further examine this interaction and its potential pathogenic effects in ALS4. PUBLIC HEALTH RELEVANCE: The potential knowledge gained from this research is an improved understanding of the causes of neuronal death in familial forms of ALS and Ataxia. Murine models being developed as part of the study could also prove highly useful and would eventually be shared with other interested investigators. Since there is currently no cure or preventive treatment for these conditions, any knowledge gained has the potential to provide future diagnostic and therapeutic interventions for these patients.