Mutation I810N in the α3 isoform of Na+,K +-ATPase causes impairments in the sodium pump and hyperexcitability in the CNS
In a mouse mutagenesis screen,weisolated a mutant, Myshkin (Myk), with autosomal dominant complex partial and secondarily generalized seizures, a greatly reduced threshold for hippocampal seizures in vitro, posttetanic hyperexcitability of the CA3-CA1 hippocampal pathway, and neuronal degeneration in the hippocampus. Positional cloning and functional analysis revealed that Myk/+ mice carry a mutation (I810N) which renders the normally expressed Na +,K+-. ATPase α3 isoform inactive. Total Na +,K+-ATPase activity was reduced by 42% in Myk/+ brain. The epilepsy in Myk/+ mice and in vitro hyperexcitability could be prevented by delivery of additional copies of wild-type Na+,K+-ATPase α3 by transgenesis, which also rescued Na+,K+-ATPase activity. Our findings reveal the functional significance of the Na +,K+-ATPase α3 isoform in the control of epileptiform activity and seizure behavior.
Clapcote S.J., Duffy S., Xie G., Kirshenbaum G., Bechard A.R., Schack V.R., Petersen J., Sinai L., Saab B.J., Lerch J.P., Minassian B.A., Ackerley C.A., Sled J.G., Cortez M.A., Henderson J.T., Vilsen B., Roder J.C. (2009). Proceedings of the National Academy of Sciences of the United States of America, 106, 14085-14090 doi: 10.1073/pnas.0904817106