title: KCNC3(R420H), a K(+) channel mutation causative in spinocerebellar ataxia 13 displays aberrant intracellular trafficking.
abstract: Spinocerebellar ataxia 13 (SCA13) is an autosomal dominant disease resulting from mutations in KCNC3 (Kv3.3), a voltage-gated potassium channel. The KCNC3(R420H) mutation was first identified as causative for SCA13 in a four-generation Filipino kindred with over 20 affected individuals. Electrophysiological analyses in oocytes previously showed that this mutation did not lead to a functional channel and displayed a dominant negative phenotype. In an effort to identify the molecular basis of this allelic form of SCA13, we first determined that human KCNC3(WT) and KCNC3(R420H) display disparate post-translational modifications, and the mutant protein has reduced complex glycan adducts. Immunohistochemical analyses demonstrated that KCNC3(R420H) was not properly trafficking to the plasma membrane and surface biotinylation demonstrated that KCNC3(R420H) exhibited only 24% as much surface expression as KCNC3(WT). KCNC3(R420H) trafficked through the ER but was retained in the Golgi. KCNC3(R420H) expression results in altered Golgi and cellular morphology. Electron microscopy of KCNC3(R420H) localization further supports retention in the Golgi. These results are specific to the KCNC3(R420H) allele and provide new insight into the molecular basis of disease manifestation in SCA13.
authors.affiliation: Department of Neurology, University of Florida, Gainesville, FL 32611, USA; McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32611, USA.
authors.forename: Carolina
authors.initials: C
authors.lastname: Gallego-Iradi
authors.affiliation: Department of Neuroscience College of Medicine, University of Florida, Gainesville, FL 32611, USA; McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32611, USA.
authors.forename: Justin S
authors.initials: JS
authors.lastname: Bickford
authors.affiliation: Department of Neurology, University of Florida, Gainesville, FL 32611, USA; McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32611, USA.
authors.forename: Swati
authors.initials: S
authors.lastname: Khare
authors.affiliation: Department of Neurology, University of Florida, Gainesville, FL 32611, USA; McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32611, USA.
authors.forename: Alexis
authors.initials: A
authors.lastname: Hall
authors.affiliation: Department of Neurology, University of Florida, Gainesville, FL 32611, USA; McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32611, USA.
authors.forename: Jerelyn A
authors.initials: JA
authors.lastname: Nick
authors.affiliation: Department of Neurology, University of Florida, Gainesville, FL 32611, USA; McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32611, USA.
authors.forename: Donya
authors.initials: D
authors.lastname: Salmasinia
authors.affiliation: Department of Endocrinology, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA.
authors.forename: Kolja
authors.initials: K
authors.lastname: Wawrowsky
authors.affiliation: Department of Pathology, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA.
authors.forename: Serguei
authors.initials: S
authors.lastname: Bannykh
authors.affiliation: Department of Neurology, University of Utah School of Medicine, Salt Lake City, UT 84123, USA.
authors.forename: Duong P
authors.initials: DP
authors.lastname: Huynh
authors.affiliation: Department of Neurology, University of Florida, Gainesville, FL 32611, USA; McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32611, USA.
authors.forename: Diego E
authors.initials: DE
authors.lastname: Rincon-Limas
authors.affiliation: Department of Neurology, University of Utah School of Medicine, Salt Lake City, UT 84123, USA.
authors.forename: Stefan M
authors.initials: SM
authors.lastname: Pulst
authors.affiliation: Department of Neuroscience College of Medicine, University of Florida, Gainesville, FL 32611, USA; McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32611, USA.
authors.forename: Harry S
authors.initials: HS
authors.lastname: Nick
authors.affiliation: Department of Neurology, University of Florida, Gainesville, FL 32611, USA; Department of Neuroscience College of Medicine, University of Florida, Gainesville, FL 32611, USA; McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32611, USA.
authors.forename: Pedro
authors.initials: P
authors.lastname: Fernandez-Funez
authors.affiliation: Department of Neurology, University of Florida, Gainesville, FL 32611, USA; Department of Neuroscience College of Medicine, University of Florida, Gainesville, FL 32611, USA; McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32611, USA. Electronic address: mwaters@neurology.ufl.edu.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Waters
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001120:Arginine / Q000235:genetics*; D019921:Biotinylation; D019556:COS Cells; D015820:Cadherins / Q000378:metabolism; D002522:Chlorocebus aethiops; D003593:Cytoplasm / Q000235:genetics / Q000378:metabolism; D004330:Drosophila; D029721:Drosophila Proteins / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005260:Female; D006639:Histidine / Q000235:genetics*; D006801:Humans; D007424:Intracellular Fluid / Q000378:metabolism*; D008297:Male; D009154:Mutation / Q000235:genetics*; D009865:Oocytes; D011499:Protein Processing, Post-Translational; D021381:Protein Transport; D051670:Shaw Potassium Channels / Q000235:genetics*; D020754:Spinocerebellar Ataxias / Q000151:congenital; D013132:Spinocerebellar Degenerations / Q000235:genetics* / Q000378:metabolism; D014162:Transfection
chemical_list: D015820:Cadherins; D029721:Drosophila Proteins; C489594:KCNC3 protein, human; D051670:Shaw Potassium Channels; D006639:Histidine; D001120:Arginine
keywords: Dominant inheritance; Golgi; KCNC3; Protein trafficking; SCA13; Spinocerebellar ataxia; Voltage-gated potassium channel