title: TMEM43 mutation p.S358L alters intercalated disc protein expression and reduces conduction velocity in arrhythmogenic right ventricular cardiomyopathy.
abstract: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a myocardial disease characterized by fibro-fatty replacement of myocardium in the right ventricular free wall and frequently results in life-threatening ventricular arrhythmias and sudden cardiac death. A heterozygous missense mutation in the transmembrane protein 43 (TMEM43) gene, p.S358L, has been genetically identified to cause autosomal dominant ARVC type 5 in a founder population from the island of Newfoundland, Canada. Little is known about the function of the TMEM43 protein or how it leads to the pathogenesis of ARVC. We sought to determine the distribution of TMEM43 and the effect of the p.S358L mutation on the expression and distribution of various intercalated (IC) disc proteins as well as functional effects on IC disc gap junction dye transfer and conduction velocity in cell culture. Through Western blot analysis, transmission electron microscopy (TEM), immunofluorescence (IF), and electrophysiological analysis, our results showed that the stable expression of p.S358L mutation in the HL-1 cardiac cell line resulted in decreased Zonula Occludens (ZO-1) expression and the loss of ZO-1 localization to cell-cell junctions. Junctional Plakoglobin (JUP) and α-catenin proteins were redistributed to the cytoplasm with decreased localization to cell-cell junctions. Connexin-43 (Cx43) phosphorylation was altered, and there was reduced gap junction dye transfer and conduction velocity in mutant TMEM43-transfected cells. These observations suggest that expression of the p.S358L mutant of TMEM43 found in ARVC type 5 may affect localization of proteins involved in conduction, alter gap junction function and reduce conduction velocity in cardiac tissue.
authors.affiliation: Physiology and Experimental Medicine, The Hospital for Sick Children and Research Institute, Toronto, Ontario, Canada.
authors.forename: Vinayakumar
authors.initials: V
authors.lastname: Siragam
authors.affiliation: Physiology and Experimental Medicine, The Hospital for Sick Children and Research Institute, Toronto, Ontario, Canada.
authors.forename: Xuezhi
authors.initials: X
authors.lastname: Cui
authors.affiliation: Division of Cardiology, University Health Network, Toronto, Ontario, Canada.
authors.forename: Stephane
authors.initials: S
authors.lastname: Masse
authors.affiliation: Division of Pathology, The Hospital for Sick Children and Research Institute, Toronto, Ontario, Canada.
authors.forename: Cameron
authors.initials: C
authors.lastname: Ackerley
authors.affiliation: Physiology and Experimental Medicine, The Hospital for Sick Children and Research Institute, Toronto, Ontario, Canada.
authors.forename: Shabana
authors.initials: S
authors.lastname: Aafaqi
authors.affiliation: Physiology and Experimental Medicine, The Hospital for Sick Children and Research Institute, Toronto, Ontario, Canada.
authors.forename: Linn
authors.initials: L
authors.lastname: Strandberg
authors.affiliation: Genetics and Genome Biology, The Hospital for Sick Children and Research Institute, Toronto, Ontario, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Tropak
authors.affiliation: Physiology and Experimental Medicine, The Hospital for Sick Children and Research Institute, Toronto, Ontario, Canada.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Fridman
authors.affiliation: Division of Cardiology, University Health Network, Toronto, Ontario, Canada.
authors.forename: Kumaraswamy
authors.initials: K
authors.lastname: Nanthakumar
authors.affiliation: Advanced Micro and Nanosystems Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.affiliation: Advanced Micro and Nanosystems Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Yu
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Physiology and Experimental Medicine, The Hospital for Sick Children and Research Institute, Toronto, Ontario, Canada.
authors.forename: Bin
authors.initials: B
authors.lastname: Su
authors.affiliation: Physiology and Experimental Medicine, The Hospital for Sick Children and Research Institute, Toronto, Ontario, Canada.
authors.forename: Caroline
authors.initials: C
authors.lastname: Wang
authors.affiliation: Physiology and Experimental Medicine, The Hospital for Sick Children and Research Institute, Toronto, Ontario, Canada.
authors.forename: Xiaoru
authors.initials: X
authors.lastname: Liu
authors.affiliation: Physiology and Experimental Medicine, The Hospital for Sick Children and Research Institute, Toronto, Ontario, Canada.
authors.forename: Yuqing
authors.initials: Y
authors.lastname: Yan
authors.affiliation: Physiology and Experimental Medicine, The Hospital for Sick Children and Research Institute, Toronto, Ontario, Canada.
authors.forename: Ariel
authors.initials: A
authors.lastname: Mendlowitz
authors.affiliation: Physiology and Experimental Medicine, The Hospital for Sick Children and Research Institute, Toronto, Ontario, Canada.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Hamilton
mesh_terms: D019571:Arrhythmogenic Right Ventricular Dysplasia / Q000235:genetics* / Q000503:physiopathology; D003593:Cytoplasm; D003896:Desmosomes / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000235:genetics*; D017629:Gap Junctions / Q000235:genetics; D005786:Gene Expression Regulation; D006801:Humans; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics; D020125:Mutation, Missense; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation
chemical_list: D008565:Membrane Proteins; C528696:TMEM43 protein, human