Cation leak through the ATP1A3 pump causes spasticity and intellectual disability

Daniel G. Calame, Cristina Moreno Vadillo, Seth Berger, Timothy Lotze, Marwan Shinawi, Javaher Poupak, Corina Heller, Julie Cohen, Richard Person, Aida Telegrafi, Chalongchai Phitsanuwong, Kaylene Fiala, Isabelle Thiffault, Florencia Del Viso, Dihong Zhou, Emily A. Fleming, Tomi Pastinen, Ali Fatemi, Sruthi Thomas, Samuel I. PascualRosa J. Torres, Carmen Prior, Clara Gómez-González, Saskia Biskup, James R. Lupski, Dragan Maric, Miguel Holmgren, Debra Regier, Sho T. Yano

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

ATP1A3 encodes the α3 subunit of the sodium-potassium ATPase, one of two isoforms responsible for powering electrochemical gradients in neurons. Heterozygous pathogenic ATP1A3 variants produce several distinct neurological syndromes, yet the molecular basis for phenotypic variability is unclear. We report a novel recurrent variant, ATP1A3(NM_152296.5):c.2324C>T; p.(Pro775Leu), in nine individuals associated with the primary clinical features of progressive or non-progressive spasticity and developmental delay/intellectual disability. No patients fulfil diagnostic criteria for ATP1A3-associated syndromes, including alternating hemiplegia of childhood, rapid-onset dystonia-parkinsonism or cerebellar ataxia-areflexia-pes cavus-optic atrophy-sensorineural hearing loss (CAPOS), and none were suspected of having an ATP1A3-related disorder. Uniquely among known ATP1A3 variants, P775L causes leakage of sodium ions and protons into the cell, associated with impaired sodium binding/occlusion kinetics favouring states with fewer bound ions. These phenotypic and electrophysiologic studies demonstrate that ATP1A3:c.2324C>T; p.(Pro775Leu) results in mild ATP1A3-related phenotypes resembling complex hereditary spastic paraplegia or idiopathic spastic cerebral palsy. Cation leak provides a molecular explanation for this genotype-phenotype correlation, adding another mechanism to further explain phenotypic variability and highlighting the importance of biophysical properties beyond ion transport rate in ion transport diseases.

Original languageEnglish
Pages (from-to)3162-3171
Number of pages10
JournalBrain
Volume146
Issue number8
DOIs
StatePublished - Aug 1 2023

Keywords

  • ATP1A3
  • neurodevelopmental disorders
  • sodium-potassium ATPase
  • spastic paraparesis
  • spasticity

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