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)
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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.
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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
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Background:
Chemotherapy-induced peripheral neuropathy (CIPN) is a serious therapy-limiting side effect of commonly used anticancer drugs. Previous studies suggest that lipids may play a role in CIPN. Therefore, the present study aimed to identify the particular types of lipids that are regulated as a consequence of paclitaxel administration and may be associated with the occurrence of post-therapeutic neuropathy.
Methods:
High-resolution mass spectrometry lipidomics was applied to quantify d=255 different lipid mediators in the blood of n=31 patients drawn before and after paclitaxel therapy for breast cancer treatment. A variety of supervised statistical and machine-learning methods was applied to identify lipids that were regulated during paclitaxel therapy or differed among patients with and without post-therapeutic neuropathy.
Results:
Twenty-seven lipids were identified that carried relevant information to train machine learning algorithms to identify, in new cases, whether a blood sample was drawn before or after paclitaxel therapy with a median balanced accuracy of up to 90%. One of the top hits, sphinganine-1-phosphate (SA1P), was found to induce calcium transients in sensory neurons via the transient receptor potential vanilloid 1 (TRPV1) channel and sphingosine-1-phosphate receptors.SA1P also showed different blood concentrations between patients with and without neuropathy.
Conclusions:
Present findings suggest a role for sphinganine-1-phosphate in paclitaxel-induced biological changes associated with neuropathic side effects. The identified SA1P, through its receptors, may provide a potential drug target for co-therapy with paclitaxel to reduce one of its major and therapy-limiting side effects.
Funding:
This work was supported by the Deutsche Forschungsgemeinschaft (German Research Foundation, DFG, Grants SFB1039 A09 and Z01) and by the Fraunhofer Foundation Project: Neuropathic Pain as well as the Fraunhofer Cluster of Excellence for Immune-Mediated Diseases (CIMD). This work was also supported by the Leistungszentrum Innovative Therapeutics (TheraNova) funded by the Fraunhofer Society and the Hessian Ministry of Science and Arts. Jörn Lötsch was supported by the Deutsche Forschungsgemeinschaft (DFG LO 612/16-1).
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