A missense mutation converts the Na+,K+-ATPase into an ion channel and causes therapy-resistant epilepsy
The ion pump Na+,K+-ATPase is a critical determinant of neuronal excitability; however, its role in the etiology of diseases of the central nervous system (CNS) is largely unknown. We describe here the molecular phenotype of a Trp931Arg mutation of the Na+,K+-ATPase catalytic α1 subunit in an infant...
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Published in | The Journal of biological chemistry Vol. 297; no. 6; p. 101355 |
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Main Authors | , , , , , , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
Elsevier Inc
01.12.2021
American Society for Biochemistry and Molecular Biology |
Subjects | |
Online Access | Get full text |
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Summary: | The ion pump Na+,K+-ATPase is a critical determinant of neuronal excitability; however, its role in the etiology of diseases of the central nervous system (CNS) is largely unknown. We describe here the molecular phenotype of a Trp931Arg mutation of the Na+,K+-ATPase catalytic α1 subunit in an infant diagnosed with therapy-resistant lethal epilepsy. In addition to the pathological CNS phenotype, we also detected renal wasting of Mg2+. We found that membrane expression of the mutant α1 protein was low, and ion pumping activity was lost. Arginine insertion into membrane proteins can generate water-filled pores in the plasma membrane, and our molecular dynamic (MD) simulations of the principle states of Na+,K+-ATPase transport demonstrated massive water inflow into mutant α1 and destabilization of the ion-binding sites. MD simulations also indicated that a water pathway was created between the mutant arginine residue and the cytoplasm, and analysis of oocytes expressing mutant α1 detected a nonspecific cation current. Finally, neurons expressing mutant α1 were observed to be depolarized compared with neurons expressing wild-type protein, compatible with a lowered threshold for epileptic seizures. The results imply that Na+,K+-ATPase should be considered a neuronal locus minoris resistentia in diseases associated with epilepsy and with loss of plasma membrane integrity. |
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Bibliography: | ObjectType-Case Study-2 SourceType-Scholarly Journals-1 ObjectType-Feature-4 content type line 23 ObjectType-Report-1 ObjectType-Article-3 These authors contributed equally to this work as senior authors. These authors contributed equally to this work. |
ISSN: | 0021-9258 1083-351X 1083-351X |
DOI: | 10.1016/j.jbc.2021.101355 |