Two de novo GluN2B mutations affect multiple NMDAR-functions and instigate severe pediatric encephalopathy
- Technion- Israel Institute of Technology, Israel
- Clalit health services, Israel
- Rambam medical center, Israel
- Tel Aviv University, Israel
- 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)
-
Two de novo GluN2B mutations affect multiple NMDAR-functions and instigate severe pediatric encephalopathyDryad Digital Repository, doi:10.5061/dryad.1jwstqjv3.
Article and author information
Author details
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).
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.
Metrics
-
- 1,960
- views
-
- 222
- downloads
-
- 14
- citations
Views, downloads and citations are aggregated across all versions of this paper published by eLife.
Download links
A two-part list of links to download the article, or parts of the article, in various formats.
Downloads (link to download the article as PDF)
Open citations (links to open the citations from this article in various online reference manager services)
Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)
Two de novo GluN2B mutations affect multiple NMDAR-functions and instigate severe pediatric encephalopathy
eLife 10:e67555.
https://doi.org/10.7554/eLife.67555
Further reading
-
- Medicine
Gremlin-1 has been implicated in liver fibrosis in metabolic dysfunction-associated steatohepatitis (MASH) via inhibition of bone morphogenetic protein (BMP) signalling and has thereby been identified as a potential therapeutic target. Using rat in vivo and human in vitro and ex vivo model systems of MASH fibrosis, we show that neutralisation of Gremlin-1 activity with monoclonal therapeutic antibodies does not reduce liver inflammation or liver fibrosis. Still, Gremlin-1 was upregulated in human and rat MASH fibrosis, but expression was restricted to a small subpopulation of COL3A1/THY1+ myofibroblasts. Lentiviral overexpression of Gremlin-1 in LX-2 cells and primary hepatic stellate cells led to changes in BMP-related gene expression, which did not translate to increased fibrogenesis. Furthermore, we show that Gremlin-1 binds to heparin with high affinity, which prevents Gremlin-1 from entering systemic circulation, prohibiting Gremlin-1-mediated organ crosstalk. Overall, our findings suggest a redundant role for Gremlin-1 in the pathogenesis of liver fibrosis, which is unamenable to therapeutic targeting.
-
- Medicine
- Neuroscience
A complex extracted from the amniotic membrane in humans reduces post-surgical pain in mice by directly inhibiting pain-sensing neurons.
