title: Missense mutations in plakophilin-2 cause sodium current deficit and associate with a Brugada syndrome phenotype.
abstract: BACKGROUND
  Brugada syndrome (BrS) primarily associates with the loss of sodium channel function. Previous studies showed features consistent with sodium current (INa) deficit in patients carrying desmosomal mutations, diagnosed with arrhythmogenic cardiomyopathy (or arrhythmogenic right ventricular cardiomyopathy). Experimental models showed correlation between the loss of expression of desmosomal protein plakophilin-2 (PKP2) and reduced INa. We hypothesized that PKP2 variants that reduce INa could yield a BrS phenotype, even without overt structural features characteristic of arrhythmogenic right ventricular cardiomyopathy.
  
  
  RESULTS
  We searched for PKP2 variants in the genomic DNA of 200 patients with a BrS diagnosis, no signs of arrhythmogenic cardiomyopathy, and no mutations in BrS-related genes SCN5A, CACNa1c, GPD1L, and MOG1. We identified 5 cases of single amino acid substitutions. Mutations were tested in HL-1-derived cells endogenously expressing NaV1.5 but made deficient in PKP2 (PKP2-KD). Loss of PKP2 caused decreased INa and NaV1.5 at the site of cell contact. These deficits were restored by the transfection of wild-type PKP2, but not of BrS-related PKP2 mutants. Human induced pluripotent stem cell cardiomyocytes from a patient with a PKP2 deficit showed drastically reduced INa. The deficit was restored by transfection of wild type, but not BrS-related PKP2. Super-resolution microscopy in murine PKP2-deficient cardiomyocytes related INa deficiency to the reduced number of channels at the intercalated disc and increased separation of microtubules from the cell end.
  
  
  CONCLUSIONS
  This is the first systematic retrospective analysis of a patient group to define the coexistence of sodium channelopathy and genetic PKP2 variations. PKP2 mutations may be a molecular substrate leading to the diagnosis of BrS.
authors.affiliation: Leon H. Charney Division of Cardiology (M.C., X.L., M.Z., E.A.-P., A.P., H.C.G., S.P., M.D.), and Cardiovascular Genetics Program (M.C., S.P.), NYU School of Medicine, New York, NY; Molecular Cardiology, Maugeri Foundation, Pavia, Italy (V.N., C.N., S.P.); Del E. Webb Center for Neuroscience, Aging & Stem Cell Research, Sanford-Burnham Medical Research Institute, La Jolla, CA (C.K., T.T., H.-S.V.C.); Department of Bioscience and Biotechnology, Sejong University, Seoul, Korea (C.K.); Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, MD (D.P.J.); and Department of Pharmacology, NYU School of Medicine, New York, NY (E.R.).
authors.forename: Marina
authors.initials: M
authors.lastname: Cerrone
authors.forename: Xianming
authors.initials: X
authors.lastname: Lin
authors.forename: Mingliang
authors.initials: M
authors.lastname: Zhang
authors.forename: Esperanza
authors.initials: E
authors.lastname: Agullo-Pascual
authors.forename: Anna
authors.initials: A
authors.lastname: Pfenniger
authors.forename: Halina
authors.initials: H
authors.lastname: Chkourko Gusky
authors.forename: Valeria
authors.initials: V
authors.lastname: Novelli
authors.forename: Changsung
authors.initials: C
authors.lastname: Kim
authors.forename: Tiara
authors.initials: T
authors.lastname: Tirasawadichai
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Judge
authors.forename: Eli
authors.initials: E
authors.lastname: Rothenberg
authors.forename: Huei-Sheng Vincent
authors.initials: HS
authors.lastname: Chen
authors.forename: Carlo
authors.initials: C
authors.lastname: Napolitano
authors.forename: Silvia G
authors.initials: SG
authors.lastname: Priori
authors.forename: Mario
authors.initials: M
authors.lastname: Delmar
mesh_terms: D000328:Adult; D000818:Animals; D053840:Brugada Syndrome / Q000235:genetics* / Q000378:metabolism* / Q000503:physiopathology; D002460:Cell Line; D004195:Disease Models, Animal; D005260:Female; D005838:Genotype; D006329:Heart Conduction System / Q000503:physiopathology; D006801:Humans; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains; D008875:Middle Aged; D020125:Mutation, Missense; D032383:Myocytes, Cardiac / Q000378:metabolism / Q000473:pathology; D062554:NAV1.5 Voltage-Gated Sodium Channel / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010375:Pedigree; D010641:Phenotype; D051191:Plakophilins / Q000235:genetics*; D012189:Retrospective Studies; D015222:Sodium Channels / Q000172:deficiency* / Q000378:metabolism
chemical_list: D062554:NAV1.5 Voltage-Gated Sodium Channel; C495337:PKP2 protein, human; C495338:Pkp2 protein, mouse; D051191:Plakophilins; C568321:Scn5a protein, mouse; D015222:Sodium Channels
keywords: Brugada syndrome; arrhythmogenic right ventricular dysplasia-cardiomyopathy; desmosomes; plakophilin 2; sodium channels