title: Functional characterization of the novel DES mutation p.L136P associated with dilated cardiomyopathy reveals a dominant filament assembly defect.
abstract: BACKGROUND
  Dilated cardiomyopathy (DCM) could be caused by mutations in more than 40 different genes. However, the pathogenic impact of specific mutations is in most cases unknown complicating the genetic counseling of affected families. Therefore, functional studies could contribute to distinguish pathogenic mutations and benign variants. Here, we present a novel heterozygous DES missense variant (c.407C>T; p.L136P) identified by next generation sequencing in a DCM patient. DES encodes the cardiac intermediate filament protein desmin, which has important functions in mechanical stabilization and linkage of the cell structures in cardiomyocytes.
  
  
  RESULTS
  Cell transfection experiments and assembly assays of recombinant desmin in combination with atomic force microscopy were used to investigate the impact of this novel DES variant on filament formation. Desmin-p.L136P forms cytoplasmic aggregates indicating a severe intrinsic filament assembly defect of this mutant. Co-transfection experiments of wild-type and mutant desmin conjugated to different fluorescence proteins revealed a dominant affect of this mutant on filament assembly. These experiments were complemented by apertureless scanning near-field optical microscopy.
  
  
  CONCLUSIONS
  In vitro analysis demonstrated that desmin-p.L136P is unable to form regular filaments and accumulate instead within the cytoplasm. Therefore, we classified DES-p.L136P as a likely pathogenic mutation. In conclusion, the functional characterization of DES-p.L136P might have relevance for the genetic counseling of affected families with similar DES mutations and could contribute to distinguish pathogenic mutations from benign rare variants.
authors.affiliation: Erich and Hanna Klessmann Institute for Cardiovascular Research & Development (EHKI), Heart and Diabetes Center NRW, Ruhr University Bochum, D-32545 Bad Oeynhausen, Germany; Libin Cardiovascular Institute of Alberta, Department of Cardiac Sciences, University of Calgary, 3280 Hospital Drive NW, T2N4Z6 Calgary, AB, Canada. Electronic address: Andreas.Brodehl@web.de.
authors.forename: Andreas
authors.initials: A
authors.lastname: Brodehl
authors.affiliation: Experimental Biophysics and Applied Nanoscience, Faculty of Physics and Bielefeld Institute for Biophysics and Nanoscience (BINAS), Bielefeld University, D-33615 Bielefeld, Germany.
authors.forename: Mareike
authors.initials: M
authors.lastname: Dieding
authors.affiliation: Experimental Biophysics and Applied Nanoscience, Faculty of Physics and Bielefeld Institute for Biophysics and Nanoscience (BINAS), Bielefeld University, D-33615 Bielefeld, Germany.
authors.forename: Niklas
authors.initials: N
authors.lastname: Biere
authors.affiliation: Department of Cardiovascular Physiology, Ruhr University Bochum, D-44780 Bochum, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Unger
authors.affiliation: Erich and Hanna Klessmann Institute for Cardiovascular Research & Development (EHKI), Heart and Diabetes Center NRW, Ruhr University Bochum, D-32545 Bad Oeynhausen, Germany.
authors.forename: Bärbel
authors.initials: B
authors.lastname: Klauke
authors.affiliation: Experimental Biophysics and Applied Nanoscience, Faculty of Physics and Bielefeld Institute for Biophysics and Nanoscience (BINAS), Bielefeld University, D-33615 Bielefeld, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Walhorn
authors.affiliation: Erich and Hanna Klessmann Institute for Cardiovascular Research & Development (EHKI), Heart and Diabetes Center NRW, Ruhr University Bochum, D-32545 Bad Oeynhausen, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Gummert
authors.affiliation: Erich and Hanna Klessmann Institute for Cardiovascular Research & Development (EHKI), Heart and Diabetes Center NRW, Ruhr University Bochum, D-32545 Bad Oeynhausen, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Schulz
authors.affiliation: Department of Cardiovascular Physiology, Ruhr University Bochum, D-44780 Bochum, Germany.
authors.forename: Wolfgang A
authors.initials: WA
authors.lastname: Linke
authors.affiliation: Libin Cardiovascular Institute of Alberta, Department of Cardiac Sciences, University of Calgary, 3280 Hospital Drive NW, T2N4Z6 Calgary, AB, Canada.
authors.forename: Brenda
authors.initials: B
authors.lastname: Gerull
authors.affiliation: Neurologische Klinik und Poliklinik, Universitätsklinikum Bergmannsheil, Buerkle-de-la-Camp-Platz 1, D-44789 Bochum, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Vorgert
authors.affiliation: Experimental Biophysics and Applied Nanoscience, Faculty of Physics and Bielefeld Institute for Biophysics and Nanoscience (BINAS), Bielefeld University, D-33615 Bielefeld, Germany.
authors.forename: Dario
authors.initials: D
authors.lastname: Anselmetti
authors.affiliation: Erich and Hanna Klessmann Institute for Cardiovascular Research & Development (EHKI), Heart and Diabetes Center NRW, Ruhr University Bochum, D-32545 Bad Oeynhausen, Germany. Electronic address: hmilting@hdz-nrw.de.
authors.forename: Hendrik
authors.initials: H
authors.lastname: Milting
mesh_terms: D000595:Amino Acid Sequence; D002311:Cardiomyopathy, Dilated / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D003893:Desmin / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D003896:Desmosomes / Q000378:metabolism / Q000648:ultrastructure; D005260:Female; D015870:Gene Expression; D005799:Genes, Dominant; D005817:Genetic Counseling; D057809:HEK293 Cells; D006579:Heterozygote; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D007382:Intermediate Filaments / Q000378:metabolism* / Q000648:ultrastructure; D008297:Male; D008875:Middle Aged; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D032383:Myocytes, Cardiac / Q000378:metabolism / Q000648:ultrastructure; D010375:Pedigree; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D003893:Desmin; D011993:Recombinant Fusion Proteins
keywords: Desmin; Desmosomes; Dilated cardiomyopathy; Intermediate filaments; Myofibrillar myopathy