title: Alternating Hemiplegia of Childhood mutations have a differential effect on Na(+),K(+)-ATPase activity and ouabain binding.
abstract: De novo mutations in ATP1A3, the gene encoding the α3-subunit of Na(+),K(+)-ATPase, are associated with the neurodevelopmental disorder Alternating Hemiplegia of Childhood (AHC). The aim of this study was to determine the functional consequences of six ATP1A3 mutations (S137Y, D220N, I274N, D801N, E815K, and G947R) associated with AHC. Wild type and mutant Na(+),K(+)-ATPases were expressed in Sf9 insect cells using the baculovirus expression system. Ouabain binding, ATPase activity, and phosphorylation were absent in mutants I274N, E815K and G947R. Mutants S137Y and D801N were able to bind ouabain, although these mutants lacked ATPase activity, phosphorylation, and the K(+)/ouabain antagonism indicative of modifications in the cation binding site. Mutant D220N showed similar ouabain binding, ATPase activity, and phosphorylation to wild type Na(+),K(+)-ATPase. Functional impairment of Na(+),K(+)-ATPase in mutants S137Y, I274N, D801N, E815K, and G947R might explain why patients having these mutations suffer from AHC. Moreover, mutant D801N is able to bind ouabain, whereas mutant E815K shows a complete loss of function, possibly explaining the different phenotypes for these mutations.
authors.affiliation: Department of Pharmacology and Toxicology 149, Radboud University Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands. Electronic address: Karl.Weigand@radboudumc.nl.
authors.forename: Karl M
authors.initials: KM
authors.lastname: Weigand
authors.affiliation: Department of Pharmacology and Toxicology 149, Radboud University Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands. Electronic address: Muriel.Messchaert@radboudumc.nl.
authors.forename: Muriël
authors.initials: M
authors.lastname: Messchaert
authors.affiliation: Department of Biochemistry 286, Radboud University Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands. Electronic address: H.Swarts@ncmls.ru.nl.
authors.forename: Herman G P
authors.initials: HG
authors.lastname: Swarts
authors.affiliation: Department of Pharmacology and Toxicology 149, Radboud University Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands. Electronic address: Frans.Russel@radboudumc.nl.
authors.forename: Frans G M
authors.initials: FG
authors.lastname: Russel
authors.affiliation: Department of Pharmacology and Toxicology 149, Radboud University Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands. Electronic address: Jan.Koenderink@radboudumc.nl.
authors.forename: Jan B
authors.initials: JB
authors.lastname: Koenderink
mesh_terms: D000818:Animals; D002460:Cell Line; D020022:Genetic Predisposition to Disease; D006429:Hemiplegia / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D009154:Mutation; D010042:Ouabain / Q000378:metabolism*; D010641:Phenotype; D010766:Phosphorylation; D011188:Potassium / Q000378:metabolism; D011485:Protein Binding; D017433:Protein Structure, Secondary; D061987:Sf9 Cells; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018411:Spodoptera
chemical_list: C488756:ATP1A3 protein, human; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium
keywords: AHC; ATP1A3; Alpha 3; Alternating Hemiplegia of Childhood; Na(+),K(+)-ATPase