Mouse models of ATP1A1 mutation -linked neuropathies

腓骨肌萎缩症（CMT）包括一组异质性周围神经病变， 超过90个基因的突变编码Na+，K+-ATP酶（NKA）α1亚基的ATP 1A 1突变， 最近与CMT 2相关，CMT 2是一种以轴突变性为特征的CMT形式。NKA是一种异源二聚体（αβ）蛋白，可水解ATP以构建和维持所有人类细胞质膜上的Na+和K+梯度。不同组织呈现不同的NKA同工酶。ATP 1A 1广泛表达，与CMT 2相关的突变导致NKA功能丧失。在与其他疾病相关的ATP 1A 1突变体中也观察到NKA功能丧失，包括原发性醛固酮增多症和伴有癫痫发作和认知延迟的低镁血症。然而，缺乏适当的模型系统，阻止了详细了解这些ATP 1A 1突变相关疾病的病理生理学。我们实验室的长期目标是了解NKA功能的机制及其在生理和疾病状态中的作用。该提案的目的是开发和评估动物模型，以研究ATP 1A 1相关疾病，重点是CMT 2。目标1.对杂合型ATP 1A 1敲除小鼠进行综合神经病理学评价，以检验我们的中心假设，即在CMT 2患者中观察到的功能丧失突变的严重影响，包括高度可变的症状强度和发病年龄，应在ATP 1A 1 +/-小鼠中重现。目标二。使用CRE-LoxP技术开发和评估新型ATP 1A 1功能缺失突变模型，以检验以下假设：成年期一个ATP 1A 1等位基因缺失会加速CMT 2症状的发作，神经元单倍不足足以诱导CMT 2。通过使用他莫昔芬诱导的CreER系产生组织和时间依赖性条件性敲除小鼠，我们将能够确定年龄依赖性代偿机制，以及CMT 2诱导的局部或全身单倍不足的必要性。这些研究的成功完成将导致可行的NKA相关的病理生理模型，以深入了解CMT 2机制。该项目的结果将为未来测试NKA相关CMT 2的特定治疗提供工具。此外，这里概述的实验可能为其他ATP 1A 1突变相关疾病提供模型。从科学的角度，我们的研究结果将揭示NKA α1在神经元生理学中的功能作用，阐明其在外周和中枢神经系统中的重要性。这些小鼠模型将通过标准的多机构MTA提供给科学界。

Charcot-Marie-Tooth (CMT) comprises a heterogeneous group of peripheral neuropathies caused by mutations in over 90 genes. Mutation of ATP1A1, which encodes for the Na+,K+-ATPase (NKA) α1 subunit, has been recently associated with CMT2, a CMT form characterized by axonal degeneration. NKA is a heterodimeric (αβ) protein that hydrolyzes ATP to build and maintain the Na+ and K+ gradients across the plasma membrane of all human cells. Different tissues present distinct NKA isozymes. ATP1A1 is ubiquitously expressed and the mutations linked to CMT2 cause NKA loss of function. Loss of NKA function is also observed in ATP1A1 mutants associated with other diseases, including primary hyperaldosteronism and a form of hypomagnesemia accompanied by seizures and cognitive delay. However, the lack of appropriate model systems has prevented a detailed understanding of the pathophysiology of these ATP1A1 mutation linked disorders. The long-term goal of our laboratory is to understand the mechanisms of NKA function and their roles in physiological and disease states. The objective of this proposal is to develop and evaluate animal models to study ATP1A1-linked disease, with an emphasis on CMT2. Aim 1. Comprehensive neuropathic evaluation of heterozygous ATP1A1 knockout mice to test our central hypothesis, that the severe effect of loss-of-function mutations seen in CMT2 patients, including the highly variables symptom intensity and age of onset, should be recapitulated in ATP1A1+/- mice. Aim 2. Develop and evaluate novel ATP1A1 loss-of-function-mutation models using CRE-LoxP technology to test the hypotheses that deletion of one ATP1A1 allele in adulthood accelerates the onset of CMT2 symptoms and that neuronal haploinsufficiency is sufficient to induce CMT2. Through the generation of tissue- and time-dependent conditional knockout mice using tamoxifen inducible CreER lines, we will be able to determine age-dependent compensatory mechanisms, and necessity of local or systemic haploinsufficiency for CMT2 induction. Successful completion of these studies will lead to viable NKA-linked pathophysiological model to gain insight into CMT2 mechanisms. The results from this project will provide a tool for future testing of specific treatments for NKA-linked CMT2. Additionally, the experiments outlined here are likely to provide models for the other ATP1A1 mutation-linked diseases. Scientifically, our results will uncover the functional roles of NKA α1 in neuron physiology elucidating its importance in both the peripheral and central nervous systems. These mouse models will be made available to the scientific community through standard multi-institutional MTAs.