1. Genetics and Genomics
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An internal promoter underlies the difference in disease severity between N- and C-terminal truncation mutations of Titin

  1. Jun Zou
  2. Diana Tran
  3. Mai Baalbaki
  4. Ling Fung Tang
  5. Annie Poon
  6. Angelo Pelonero
  7. Erron W Titus
  8. Christiana Yuan
  9. Chenxu Shi
  10. Shruthi Patchava
  11. Elizabeth Halper
  12. Jasmine Garg
  13. Irina Movsesyan
  14. Chaoying Yin
  15. Roland Wu
  16. Lisa D Wilsbacher
  17. Jiandong Liu
  18. Ronald L Hager
  19. Shaun Coughlin
  20. Martin Jinek
  21. Clive R Pullinger
  22. John P Kane
  23. Daniel O Hart
  24. Pui-Yan Kwok
  25. Rahul C Deo  Is a corresponding author
  1. University of California, San Francisco, United States
  2. University of North Carolina at Chapel Hill, United States
  3. Brigham Young University, United States
  4. University of Zurich, United States
Research Article
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Cite this article as: eLife 2015;4:e09406 doi: 10.7554/eLife.09406

Abstract

Truncating mutations in the giant sarcomeric protein Titin result in dilated cardiomyopathy (DCM) and skeletal myopathy. The most severely affected DCM patients harbor Titin truncations in the C-terminal two-thirds of the protein, suggesting that mutation position might influence disease mechanism. Using CRISPR/Cas9 technology, we generated six zebrafish lines with Titin truncations in the N-terminal (Z-disk and I-band) and C-terminal (A-band) regions. Although all exons were constitutive, C-terminal mutations caused severe myopathy whereas N-terminal mutations demonstrated mild phenotypes. Surprisingly, neither mutation type acted as a dominant negative. Instead, we found a conserved internal promoter at the precise position where divergence in disease severity occurs, with the resulting protein product partially rescuing N-terminal truncations. In addition to its clinical implications, our work may shed light on a long-standing mystery regarding the architecture of the sarcomere.

Article and author information

Author details

  1. Jun Zou

    Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Diana Tran

    Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Mai Baalbaki

    Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Ling Fung Tang

    Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  5. Annie Poon

    Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  6. Angelo Pelonero

    Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  7. Erron W Titus

    Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  8. Christiana Yuan

    Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  9. Chenxu Shi

    Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  10. Shruthi Patchava

    Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  11. Elizabeth Halper

    Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  12. Jasmine Garg

    Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  13. Irina Movsesyan

    Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  14. Chaoying Yin

    Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  15. Roland Wu

    Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  16. Lisa D Wilsbacher

    Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  17. Jiandong Liu

    Department of Pathology and Laboratory Medicine, McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, United States
    Competing interests
    The authors declare that no competing interests exist.
  18. Ronald L Hager

    Department of Exercise Sciences, Brigham Young University, Provo, United States
    Competing interests
    The authors declare that no competing interests exist.
  19. Shaun Coughlin

    Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  20. Martin Jinek

    Department of Biochemistry, University of Zurich, Zurich, United States
    Competing interests
    The authors declare that no competing interests exist.
  21. Clive R Pullinger

    Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  22. John P Kane

    Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  23. Daniel O Hart

    Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  24. Pui-Yan Kwok

    Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  25. Rahul C Deo

    Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
    For correspondence
    rahul.deo@ucsf.edu
    Competing interests
    The authors declare that no competing interests exist.

Ethics

Animal experimentation: All zebrafish and mouse experimental work conformed to the 'Guide for the Care and Use of Laboratory Animals' published by the US National Institutes of Health (NIH Publication No. 85-23, revised 1996). Animal work was performed according to institutional guidelines with the full approval of the University of California Institutional Animal Care and Use Committee (protocols AN090013-03 and AN107039-01)

Human subjects: Human genetic studies were performed according to institutional guidelines and with the full approval of the University of California San Francisco Committee on Human Research (CHR#10-00207) and all studies performed were in keeping with the original informed consent forms. Informed consent and consent to publish was obtained from all participants.

Reviewing Editor

  1. Harry C Dietz, Howard Hughes Medical Institute and Institute of Genetic Medicine, Johns Hopkins University School of Medicine, United States

Publication history

  1. Received: June 13, 2015
  2. Accepted: October 15, 2015
  3. Accepted Manuscript published: October 16, 2015 (version 1)
  4. Version of Record published: December 1, 2015 (version 2)

Copyright

© 2015, Zou et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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