Functional correlation of ATP1A2 mutations with phenotypic spectrum: from pure hemiplegic migraine to its variant forms.

Mutations in ATP1A2, the gene encoding the α2 subunit of Na+/K+-ATPase, are the main cause of familial hemiplegic migraine type 2 (FHM2). The clinical presentation of FHM2 with mutations in the same gene varies from pure FHM to severe forms with epilepsy and intellectual disability, but the correlation of these symptoms with different ATP1A2 mutations is still unclear. Ten ATP1A2 missense mutations were selected according to different phenotypes of FHM patients. They caused pure FHM (FHM: R65W, R202Q, R593W, G762S), FHM with epilepsy (FHME: R548C, E825K, R938P), or FHM with epilepsy and intellectual disability (FHMEI: T378N, G615R, D718N). After ouabain resistance and fluorescence modification, plasmids carrying those mutations were transiently transfected into HEK293T and HeLa cells. The biochemical functions were studied including cell survival assays, membrane protein extraction, western blotting, and Na+/K+-ATPase activity tests. The electrophysiological functions of G762S, R938P, and G615R mutations were investigated in HEK293T cells using whole-cell patch-clamp. Homology modeling was performed to determine the locational distribution of ATP1A2 mutations. Compared with wild-type pumps, all mutations showed a similar level of protein expression and decreased cell viability in the presence of 1 µM ouabain, and there was no significant difference among the mutant groups. The changes in Na+/K+-ATPase activity were correlated with the severity of FHM phenotypes. In the presence of 100 µM ouabain, the Na+/K+-ATPase activity was FHM > FHME > FHMEI. The ouabain-sensitive Na+/K+-ATPase activity of each mutant was significantly lower than that of the wild-type protein, and there was no significant difference among all mutant groups. Whole-cell voltage-clamp recordings in HEK293T cells showed that the ouabain-sensitive pump currents of G615R were significantly reduced, while those of G762S and R938P were comparable to those of the wild-type strain. ATP1A2 mutations cause phenotypes ranging from pure FHM to FHM with epilepsy and intellectual disability due to varying degrees of deficits in biochemical and electrophysiological properties of Na+/K+-ATPase. Mutations associated with intellectual disability presented with severe impairment of Na+/K+-ATPase. Whether epilepsy is accompanied, or the type of epilepsy did not seem to affect the degree of impairment of pump function.

Li Y ，Tang W ，Kang L ，Kong S ，Dong Z ，Zhao D ，Liu R ，Yu S ... -  《-》

Familial hemiplegic migraine mutations affect Na,K-ATPase domain interactions.

Familial hemiplegic migraine (FHM) is a monogenic variant of migraine with aura. One of the three known causative genes, ATP1A2, which encodes the α2 isoform of Na,K-ATPase, causes FHM type 2 (FHM2). Over 50 FHM2 mutations have been reported, but most have not been characterized functionally. Here we study the molecular mechanism of Na,K-ATPase α2 missense mutations. Mutants E700K and P786L inactivate or strongly reduce enzyme activity. Glutamic acid 700 is located in the phosphorylation (P) domain and the mutation most likely disrupts the salt bridge with Lysine 35, thereby destabilizing the interaction with the actuator (A) domain. Mutants G900R and E902K are present in the extracellular loop at the interface of the α and β subunit. Both mutants likely hamper the interaction between these subunits and thereby decrease enzyme activity. Mutants E174K, R548C and R548H reduce the Na(+) and increase the K(+) affinity. Glutamic acid 174 is present in the A domain and might form a salt bridge with Lysine 432 in the nucleotide binding (N) domain, whereas Arginine 548, which is located in the N domain, forms a salt bridge with Glutamine 219 in the A domain. In the catalytic cycle, the interactions of the A and N domains affect the K(+) and Na(+) affinities, as observed with these mutants. Functional consequences were not observed for ATP1A2 mutations found in two sporadic hemiplegic migraine cases (Y9N and R879Q) and in migraine without aura (R51H and C702Y).

Swarts HG ，Weigand KM ，Venselaar H ，van den Maagdenberg AM ，Russel FG ，Koenderink JB ... -  《-》

Two de novo mutations in the Na,K-ATPase gene ATP1A2 associated with pure familial hemiplegic migraine.

Vanmolkot KR ，Kors EE ，Turk U ，Turkdogan D ，Keyser A ，Broos LA ，Kia SK ，van den Heuvel JJ ，Black DF ，Haan J ，Frants RR ，Barone V ，Ferrari MD ，Casari G ，Koenderink JB ，van den Maagdenberg AM ... -  《EUROPEAN JOURNAL OF HUMAN GENETICS》

Novel mutations in the Na+, K+-ATPase pump gene ATP1A2 associated with familial hemiplegic migraine and benign familial infantile convulsions.

Vanmolkot KR ，Kors EE ，Hottenga JJ ，Terwindt GM ，Haan J ，Hoefnagels WA ，Black DF ，Sandkuijl LA ，Frants RR ，Ferrari MD ，van den Maagdenberg AM ... -  《ANNALS OF NEUROLOGY》

A Chinese family with familial hemiplegic migraine type 2 due to a novel missense mutation in ATP1A2.

Tang W ，Zhang M ，Qiu E ，Kong S ，Li Y ，Liu H ，Dong Z ，Yu S ... -  《-》