1. Cell Biology
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Site-specific phosphorylation and caspase cleavage of GFAP are new markers of Alexander Disease severity

  1. Rachel A Battaglia
  2. Adriana S Beltran
  3. Samed Delic
  4. Raluca Dumitru
  5. Jasmine A Robinson
  6. Parijat Kabiraj
  7. Laura E Herring
  8. Victoria J Madden
  9. Namritha Ravinder
  10. Erik Willems
  11. Rhonda A Newman
  12. Roy Andrew Quinlan
  13. James E Goldman
  14. Ming-Der Perng
  15. Masaki Inagaki
  16. Natasha T Snider  Is a corresponding author
  1. University of North Carolina at Chapel Hill, United States
  2. Thermo Fisher Scientific, United States
  3. Durham University, United Kingdom
  4. Columbia University, United States
  5. National Tsing Hua University, Taiwan, Republic of China
  6. Mie University Graduate School of Medicine, Japan
Research Article
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Cite this article as: eLife 2019;8:e47789 doi: 10.7554/eLife.47789

Abstract

Alexander Disease (AxD) is a fatal neurodegenerative disorder caused by mutations in glial fibrillary acidic protein (GFAP), which supports the structural integrity of astrocytes. Over 70 GFAP missense mutations cause AxD, but the mechanism linking different mutations to disease-relevant phenotypes remains unknown. We used AxD patient brain tissue and induced pluripotent stem cell (iPSC)-derived astrocytes to investigate the hypothesis that AxD-causing mutations perturb key post-translational modifications (PTMs) on GFAP. Our findings reveal selective phosphorylation of GFAP-Ser13 in patients who died young, independently of the mutation they carried. AxD iPSC-astrocytes accumulated pSer13-GFAP in cytoplasmic aggregates within deep nuclear invaginations, resembling the hallmark Rosenthal fibers observed in vivo. Ser13 phosphorylation facilitated GFAP aggregation and was associated with increased GFAP proteolysis by caspase-6. Furthermore, caspase-6 was selectively expressed in young AxD patients, and correlated with the presence of cleaved GFAP. We reveal a novel PTM signature linking different GFAP mutations in infantile AxD.

Data availability

All data generated or analyzed during this study are included in the manuscript and supporting files. Source data files have been provided for mass spec results in Figure 1 and Supplemental Figure 6.

Article and author information

Author details

  1. Rachel A Battaglia

    Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, United States
    Competing interests
    No competing interests declared.
  2. Adriana S Beltran

    Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, United States
    Competing interests
    No competing interests declared.
  3. Samed Delic

    Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, United States
    Competing interests
    No competing interests declared.
  4. Raluca Dumitru

    Human Pluripotent Stem Cell Core Facility, University of North Carolina at Chapel Hill, Chapel Hill, United States
    Competing interests
    No competing interests declared.
  5. Jasmine A Robinson

    Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, United States
    Competing interests
    No competing interests declared.
  6. Parijat Kabiraj

    Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, United States
    Competing interests
    No competing interests declared.
  7. Laura E Herring

    Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, United States
    Competing interests
    No competing interests declared.
  8. Victoria J Madden

    Department of Pathology, University of North Carolina at Chapel Hill, Chapel Hill, United States
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-7909-7743
  9. Namritha Ravinder

    Thermo Fisher Scientific, Carlsbad, United States
    Competing interests
    Namritha Ravinder, is a paid employee of ThermoFisher Scientific, whose products were used to complete parts of the study.
  10. Erik Willems

    Thermo Fisher Scientific, Carlsbad, United States
    Competing interests
    Erik Willems, is a paid employee of ThermoFisher Scientific, whose products were used to complete parts of the study.
  11. Rhonda A Newman

    Thermo Fisher Scientific, Carlsbad, United States
    Competing interests
    Rhonda A Newman, is a paid employee of ThermoFisher Scientific, whose products were used to complete parts of the study. ThermoFisher Scientific had no role in the study design, data analysis, decision to publish, or preparation of the manuscript.
  12. Roy Andrew Quinlan

    Department of Biosciences, Durham University, Durham, United Kingdom
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-0644-4123
  13. James E Goldman

    Department of Pathology, Columbia University, New York, United States
    Competing interests
    No competing interests declared.
  14. Ming-Der Perng

    Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, Taiwan, Republic of China
    Competing interests
    No competing interests declared.
  15. Masaki Inagaki

    Department of Physiology, Mie University Graduate School of Medicine, Mie, Japan
    Competing interests
    No competing interests declared.
  16. Natasha T Snider

    Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, United States
    For correspondence
    ntsnider@med.unc.edu
    Competing interests
    Natasha T Snider, is a member of the Scientific Advisory Board for Elise's Corner Fund, which supported part of this work.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-7663-4585

Funding

Elise's Corner Fund (Research Grant)

  • Natasha T Snider

United Leukodystrophy Foundation (Research Grant)

  • Natasha T Snider

National Science Foundation (Graduate Research Fellowship)

  • Rachel A Battaglia

University of North Carolina at Chapel Hill (Department of Cell Biology and Physiology)

  • Natasha T Snider

National Institutes of Health (P30 CA016086)

  • Victoria J Madden

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Kang Shen, Howard Hughes Medical Institute, Stanford University, United States

Publication history

  1. Received: April 18, 2019
  2. Accepted: November 4, 2019
  3. Accepted Manuscript published: November 4, 2019 (version 1)
  4. Version of Record published: December 23, 2019 (version 2)

Copyright

© 2019, Battaglia 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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