Production and evaluation CMT2 mouse models of ATP1A1 loss-of-function-mutation using Cre-LoxP technology

家长补助金1-R03 NS116433-01

SUMMARY of parent grant 1-R03 NS116433-01 Charcot-Marie-Tooth disease (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. Mutation in the different NKA isozymes induces several neurological diseases. 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 the roles of NKA 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 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 CreERT2 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 mouse models of NKA-linked pathophysiology 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 nervous system. These mouse models will be made available to the scientific community through standard multi-institutional MTAs.