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  • Nilsson, MichelleLinköpings universitet,Avdelningen för neurobiologi,Medicinska fakulteten,Pantazis (author)

An epilepsy-associated KV1.2 charge-transfer-center mutation impairs KV1.2 and KV1.4 trafficking

  • Article/chapterEnglish2022

Publisher, publication year, extent ...

  • 2022-04-19
  • National Academy of Sciences,2022
  • electronicrdacarrier

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  • LIBRIS-ID:oai:DiVA.org:liu-184818
  • https://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-184818URI
  • https://doi.org/10.1073/pnas.2113675119DOI

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  • Language:English
  • Summary in:English

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  • Subject category:ref swepub-contenttype
  • Subject category:art swepub-publicationtype

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  • Significance: A child with epilepsy has a previously unreported, heterozygous mutation in KCNA2, the gene encoding KV1.2 proteins. Four KV1.2 assemble into a potassium-selective channel, a protein complex at the neuronal cell surface regulating electrical signaling. KV1.2 subunits assemble with other KV1-family members to form heterotetrameric channels, contributing to neuronal potassium-channel diversity. The most striking consequence of this mutation is preventing KV1.2-subunit trafficking, i.e., their ability to reach the cell surface. Moreover, the mutation is dominant negative, as mutant subunits can assemble with wild-type KV1.2 and KV1.4, trapping them into nontrafficking heterotetramers and decreasing their functional expression. Thus, KV1-family genes’ ability to form heterotetrameric channels is a double-edged sword, rendering KV1-family members vulnerable to dominant-negative mutations in a single member gene.Abstract: We report on a heterozygous KCNA2 variant in a child with epilepsy. KCNA2 encodes KV1.2 subunits, which form homotetrameric potassium channels and participate in heterotetrameric channel complexes with other KV1-family subunits, regulating neuronal excitability. The mutation causes substitution F233S at the KV1.2 charge transfer center of the voltage-sensing domain. Immunocytochemical trafficking assays showed that KV1.2(F233S) subunits are trafficking deficient and reduce the surface expression of wild-type KV1.2 and KV1.4: a dominant-negative phenotype extending beyond KCNA2, likely profoundly perturbing electrical signaling. Yet some KV1.2(F233S) trafficking was rescued by wild-type KV1.2 and KV1.4 subunits, likely in permissible heterotetrameric stoichiometries: electrophysiological studies utilizing applied transcriptomics and concatemer constructs support that up to one or two KV1.2(F233S) subunits can participate in trafficking-capable heterotetramers with wild-type KV1.2 or KV1.4, respectively, and that both early and late events along the biosynthesis and secretion pathway impair trafficking. These studies suggested that F233S causes a depolarizing shift of ∼48 mV on KV1.2 voltage dependence. Optical tracking of the KV1.2(F233S) voltage-sensing domain (rescued by wild-type KV1.2 or KV1.4) revealed that it operates with modestly perturbed voltage dependence and retains pore coupling, evidenced by off-charge immobilization. The equivalent mutation in the Shaker K+ channel (F290S) was reported to modestly affect trafficking and strongly affect function: an ∼80-mV depolarizing shift, disrupted voltage sensor activation and pore coupling. Our work exposes the multigenic, molecular etiology of a variant associated with epilepsy and reveals that charge-transfer-center disruption has different effects in KV1.2 and Shaker, the archetypes for potassium channel structure and function.

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  • Lindström, Sarah H,1977-Linköpings universitet,Avdelningen för neurobiologi,Medicinska fakulteten(Swepub:liu)sarli19 (author)
  • Kaneko, MakiCenter for Personalized Medicine, Children's Hospital Los Angeles, Los Angeles, CA 90027;Division of Genomic Medicine, Department of Pathology, Children's Hospital Los Angeles, Los Angeles, CA 90027 (author)
  • Wang, KaiqianLinköpings universitet,Avdelningen för neurobiologi,Medicinska fakulteten(Swepub:liu)kaiwa47 (author)
  • Minguez-Viñas, TeresaLinköpings universitet,Avdelningen för neurobiologi,Medicinska fakulteten(Swepub:liu)termi18 (author)
  • Angelini, MarinaDivision of Molecular Medicine, Department of Anesthesiology & Perioperative Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095 (author)
  • Steccanella, FedericaDivision of Molecular Medicine, Department of Anesthesiology & Perioperative Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095 (author)
  • Holder, DeborahComprehensive Epilepsy Program, Children's Hospital Los Angeles, Los Angeles, CA 90027 (author)
  • Ottolia, MichelaDivision of Molecular Medicine, Department of Anesthesiology & Perioperative Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095;UCLA Cardiovascular Theme, David Geffen School of Medicine, University of California, Los Angeles, CA 90095 (author)
  • Olcese, RiccardoDivision of Molecular Medicine, Department of Anesthesiology & Perioperative Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095;UCLA Cardiovascular Theme, David Geffen School of Medicine, University of California, Los Angeles, CA 90095;Brain Research Institute, David Geffen School of Medicine, University of California, Los Angeles, CA 90095;Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095 (author)
  • Pantazis, Antonios,1982-Linköpings universitet,Avdelningen för neurobiologi,Medicinska fakulteten,Wallenberg Center for Molecular Medicine(Swepub:liu)antpa45 (author)
  • Linköpings universitetAvdelningen för neurobiologi (creator_code:org_t)

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  • In:Proceedings of the National Academy of Sciences of the United States of America: National Academy of Sciences119:170027-84241091-6490

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