title: Mutation in S6 domain of HCN4 channel in patient with suspected Brugada syndrome modifies channel function.
abstract: Diseases such as the sick sinus and the Brugada syndrome are cardiac abnormalities, which can be caused by a number of genetic aberrances. Among them are mutations in HCN4, a gene, which encodes the hyperpolarization-activated, cyclic nucleotide-gated ion channel 4; this pacemaker channel is responsible for the spontaneous activity of the sinoatrial node. The present genetic screening of patients with suspected or diagnosed Brugada or sick sinus syndrome identified in 1 out of 62 samples the novel mutation V492F. It is located in a highly conserved site of hyperpolarization-activated cyclic nucleotide-gated (HCN)4 channel downstream of the filter at the start of the last transmembrane domain S6. Functional expression of mutant channels in HEK293 cells uncovered a profoundly reduced channel function but no appreciable impact on channel synthesis and trafficking compared to the wild type. The inward rectifying HCN4 current could be partially rescued by an expression of heteromeric channels comprising wt and mutant monomers. These heteromeric channels were responsive to cAMP but they required a more negative voltage for activation and they exhibited a lower current density than the wt channel. This suggests a dominant negative effect of the mutation in patients, which carry this heterozygous mutation. Such a modulation of HCN4 activity could be the cause of the diagnosed cardiac abnormality.
authors.affiliation: Institute of Legal Medicine, University of Frankfurt, Kennedyallee 104, 60596, Frankfurt am Main, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Biel
authors.affiliation: Department of Biosciences and CNR IBF-Mi, University of Milano, Via Celoria 26, 20133, Milan, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Aquila
authors.affiliation: Department of Biology, Plant Membrane Biophysics, Technische Universität Darmstadt, Schnittspahnstrasse 3, 64287, Darmstadt, Germany.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Hertel
authors.affiliation: Department of Biology, Plant Membrane Biophysics, Technische Universität Darmstadt, Schnittspahnstrasse 3, 64287, Darmstadt, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Berthold
authors.affiliation: Kerckhoff Heart and Thorax Center, University of Giessen, Benekestraße 2, 61231, Bad Nauheim, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Neumann
authors.affiliation: The PaceLab, Department of Biosciences, University of Milano, via Celoria 26, 20133, Milan, Italy.
authors.forename: Dario
authors.initials: D
authors.lastname: DiFrancesco
authors.affiliation: Department of Biosciences and CNR IBF-Mi, University of Milano, Via Celoria 26, 20133, Milan, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Moroni
authors.affiliation: Department of Biology, Plant Membrane Biophysics, Technische Universität Darmstadt, Schnittspahnstrasse 3, 64287, Darmstadt, Germany. thiel@bio.tu-darmstadt.de.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Thiel
authors.affiliation: Institute of Legal Medicine, University of Frankfurt, Kennedyallee 104, 60596, Frankfurt am Main, Germany.
authors.forename: Silke
authors.initials: S
authors.lastname: Kauferstein
mesh_terms: D000200:Action Potentials; D053840:Brugada Syndrome / Q000175:diagnosis / Q000235:genetics*; D057809:HEK293 Cells; D006579:Heterozygote; D006801:Humans; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels / Q000235:genetics* / Q000378:metabolism; D009124:Muscle Proteins / Q000235:genetics* / Q000378:metabolism; D020125:Mutation, Missense; D015221:Potassium Channels / Q000235:genetics* / Q000378:metabolism; D000072417:Protein Domains; D055503:Protein Multimerization; D021381:Protein Transport
chemical_list: C119587:HCN4 protein, human; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels; D009124:Muscle Proteins; D015221:Potassium Channels
keywords: Channelopathy; HCN pace making; Sick sinus/Brugada syndrome