2. Academic Validation
  3. Functional characterization of the novel DES mutation p.L136P associated with dilated cardiomyopathy reveals a dominant filament assembly defect

Functional characterization of the novel DES mutation p.L136P associated with dilated cardiomyopathy reveals a dominant filament assembly defect

  • J Mol Cell Cardiol. 2016 Feb;91:207-14. doi: 10.1016/j.yjmcc.2015.12.015.
Andreas Brodehl 1,  Mareike Dieding 2,  Niklas Biere 2,  Andreas Unger 3,  Bärbel Klauke 4,  Volker Walhorn 2,  Jan Gummert 4,  Uwe Schulz 4,  Wolfgang A Linke 3,  Brenda Gerull 5,  Matthias Vorgert 6,  Dario Anselmetti 2,  Hendrik Milting 7
Affiliations

Affiliations

  • 1 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.
  • 2 Experimental Biophysics and Applied Nanoscience, Faculty of Physics and Bielefeld Institute for Biophysics and Nanoscience (BINAS), Bielefeld University, D-33615 Bielefeld, Germany.
  • 3 Department of Cardiovascular Physiology, Ruhr University Bochum, D-44780 Bochum, Germany.
  • 4 Erich and Hanna Klessmann Institute for Cardiovascular Research & Development (EHKI), Heart and Diabetes Center NRW, Ruhr University Bochum, D-32545 Bad Oeynhausen, Germany.
  • 5 Libin Cardiovascular Institute of Alberta, Department of Cardiac Sciences, University of Calgary, 3280 Hospital Drive NW, T2N4Z6 Calgary, AB, Canada.
  • 6 Neurologische Klinik und Poliklinik, Universitätsklinikum Bergmannsheil, Buerkle-de-la-Camp-Platz 1, D-44789 Bochum, Germany.
  • 7 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.
PMID: 26724190 DOI: 10.1016/j.yjmcc.2015.12.015
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.

Methods and 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.

Conclusion: 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.

Keywords

Desmin; Desmosomes; Dilated cardiomyopathy; Intermediate filaments; Myofibrillar myopathy.

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