Mouse models of ATP1A1 mutation -linked neuropathies

Charcot-Marie-Tooth(CMT)包括由以下原因引起的一组不同的周围神经疾病 90多个基因的突变。编码Na+，K+-ATPaseα1亚单位的ATP1A1突变 最近被认为与CMT2有关，这是一种以轴突变性为特征的CMT形式。NKA是一种异二聚体(αβ)蛋白，它能水解三磷酸腺苷，以建立和维持所有人类细胞质膜上的Na+和K+梯度。不同组织表现出不同的NKA同工酶。ATP1A1广泛表达，与CMT2连锁的突变导致NKA功能丧失。在与其他疾病相关的ATP1A1突变中也观察到NKA功能的丧失，包括原发性醛固酮增多症和一种伴随癫痫发作和认知延迟的低镁血症。然而，缺乏合适的模型系统阻碍了对这些ATP1A1突变相关疾病的病理生理学的详细了解。我们实验室的长期目标是了解NKA的功能机制及其在生理和疾病状态下的作用。这项建议的目的是开发和评估研究ATP1A1相关疾病的动物模型，重点是CMT2。目的1.对ATP1A1基因敲除杂合子小鼠进行全面的神经病理学评估，以验证我们的中心假设，即在CMT2患者中发现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ATP1A1+/-小鼠中概括。目的2.应用Cre-loxP技术建立和评价新的ATP1A1功能缺失突变模型，以验证以下假设：成年后一个ATP1A1等位基因缺失会加速CMT2症状的发生，神经元单倍体功能不全足以引发CMT2。通过使用他莫昔芬可诱导的CRER系建立组织和时间依赖的条件性基因敲除小鼠，我们将能够确定依赖年龄的代偿机制，以及局部或系统单倍性不足对CMT2诱导的必要性。这些研究的成功完成将导致可行的NKA连锁的病理生理学模型，以深入了解CMT2的机制。该项目的结果将为未来测试与NKA相关的CMT2的具体治疗提供一个工具。此外，这里概述的实验可能会为其他ATP1A1突变相关疾病提供模型。从科学上讲，我们的结果将揭示NKAα1在神经生理学中的功能作用，阐明它在外周和中枢神经系统中的重要性。这些老鼠模型将通过标准的多机构多边技术协定提供给科学界。

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.