Two de novo GluN2B mutations affect multiple NMDAR-functions and instigate severe pediatric encephalopathy

  1. Shai Kellner
  2. Abeer Abbasi
  3. Ido Carmi
  4. Ronit Heinrich
  5. Tali Garin-Shkolnik
  6. Tova Hershkovitz
  7. Moshe Giladi
  8. Yoni Haitin
  9. Katrine M Johannesen
  10. Rikke Steensbjerre Møller
  11. Shai Berlin  Is a corresponding author
  1. Technion- Israel Institute of Technology, Israel
  2. Clalit health services, Israel
  3. Rambam medical center, Israel
  4. Tel Aviv University, Israel
  5. University of Southern Denmark, Denmark

Abstract

The N-methyl-D-aspartate receptors (NMDARs; GluNRS) are glutamate receptors, commonly located at excitatory synapses. Mutations affecting receptor function often lead to devastating neurodevelopmental disorders. We have identified two toddlers with different heterozygous missense mutations of the same, and highly conserved, glycine residue located in the ligand-binding-domain of GRIN2B: G689C and G689S. Structure simulations suggest severely impaired glutamate binding which we confirm by functional analysis. Both variants show three-orders of magnitude reductions in glutamate EC50, with G689S exhibiting the largest reductions observed in GRIN2B (~2000-fold). Moreover, variants multimerize with, and upregulate, GluN2Bwt-subunits, thus engendering a strong dominant-negative effect on mixed channels. In neurons, overexpression of the variants instigates suppression of synaptic GluNRs. Lastly, while exploring spermine potentiation as a potential treatment, we discovered that the variants fail to respond due to G689's novel role in proton-sensing. Together, we describe two unique variants with extreme effects on channel function. We employ protein-stability measures to explain why current (and future) LBD mutations in GluN2B primarily instigate Loss-of-Function.

Data availability

All data generated or analysed during this study are included in the manuscript and supporting files. Raw data is deposited at Dryad (doi:10.5061/dryad.1jwstqjv3)

The following data sets were generated

Article and author information

Author details

  1. Shai Kellner

    Neuroscience, Technion- Israel Institute of Technology, Haifa, Israel
    Competing interests
    The authors declare that no competing interests exist.
  2. Abeer Abbasi

    Neuroscience, Technion- Israel Institute of Technology, Haifa, Israel
    Competing interests
    The authors declare that no competing interests exist.
  3. Ido Carmi

    Neuroscience, Technion- Israel Institute of Technology, Haifa, Israel
    Competing interests
    The authors declare that no competing interests exist.
  4. Ronit Heinrich

    Neuroscience, Technion- Israel Institute of Technology, Haifa, Israel
    Competing interests
    The authors declare that no competing interests exist.
  5. Tali Garin-Shkolnik

    Dermatology, Clalit health services, Yoqneam, Israel
    Competing interests
    The authors declare that no competing interests exist.
  6. Tova Hershkovitz

    Genetics Institute, Rambam medical center, Haifa, Israel
    Competing interests
    The authors declare that no competing interests exist.
  7. Moshe Giladi

    Tel Aviv University, Tel Aviv, Israel
    Competing interests
    The authors declare that no competing interests exist.
  8. Yoni Haitin

    Tel Aviv University, Tel Aviv, Israel
    Competing interests
    The authors declare that no competing interests exist.
  9. Katrine M Johannesen

    Department of Epilepsy Genetics and Personalized Medicine Danish Epilepsy Centre, University of Southern Denmark, Dianalund, Denmark
    Competing interests
    The authors declare that no competing interests exist.
  10. Rikke Steensbjerre Møller

    Department of Epilepsy Genetics and Personalized Medicine Danish Epilepsy Centre, University of Southern Denmark, Dianalund, Denmark
    Competing interests
    The authors declare that no competing interests exist.
  11. Shai Berlin

    Neuroscience, Technion- Israel Institute of Technology, Haifa, Israel
    For correspondence
    shai.berlin@technion.ac.il
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-5153-4876

Funding

Israel Science Foundation (1096/17)

  • Shai Berlin

Teva Pharmaceutical Industries (PR783187)

  • Shai Kellner

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

Ethics

Animal experimentation: All Experiments were approved by the Technion Institutional Animal Care and Use Committee (permit SB, no. IL-129-09-17).

Reviewing Editor

  1. Moses V Chao, New York University Langone Medical Center, United States

Version history

  1. Received: February 15, 2021
  2. Accepted: June 27, 2021
  3. Accepted Manuscript published: July 2, 2021 (version 1)
  4. Version of Record published: July 6, 2021 (version 2)

Copyright

© 2021, Kellner 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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  1. Shai Kellner
  2. Abeer Abbasi
  3. Ido Carmi
  4. Ronit Heinrich
  5. Tali Garin-Shkolnik
  6. Tova Hershkovitz
  7. Moshe Giladi
  8. Yoni Haitin
  9. Katrine M Johannesen
  10. Rikke Steensbjerre Møller
  11. Shai Berlin
(2021)
Two de novo GluN2B mutations affect multiple NMDAR-functions and instigate severe pediatric encephalopathy
eLife 10:e67555.
https://doi.org/10.7554/eLife.67555

Share this article

https://doi.org/10.7554/eLife.67555

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