Purpose: RPH3A encodes a protein involved in the stabilization of GluN2A subunit of N- methyl-D-aspartate (NMDA)-type glutamate receptors at the cell surface, forming a complex essential for synaptic plasticity and cognition. We investigated the effect of variants in RPH3A in patients with neurodevelopmental disorders. Methods: By using trio-based exome sequencing, GeneMatcher, and screening of 100,000 Genomes Project data, we identified 6 heterozygous variants in RPH3A. In silico and in vitro models, including rat hippocampal neuronal cultures, have been used to characterize the effect of the variants. Results: Four cases had a neurodevelopmental disorder with untreatable epileptic seizures [p.(Gln73His)dn; p.(Arg209Lys); p.(Thr450Ser)dn; p.(Gln508His)], and 2 cases [p.(Arg235Ser); p.(Asn618Ser)dn] showed high-functioning autism spectrum disorder. Using neuronal cultures, we demonstrated that p.(Thr450Ser) and p.(Asn618Ser) reduce the synaptic localization of GluN2A; p.(Thr450Ser) also increased the surface levels of GluN2A. Electrophysiological recordings showed increased GluN2A-dependent NMDA ionotropic glutamate receptor currents for both variants and alteration of postsynaptic calcium levels. Finally, expression of the Rph3AThr450Ser variant in neurons affected dendritic spine morphology. Conclusion: Overall, we provide evidence that missense gain-of-function variants in RPH3A increase GluN2A-containing NMDA ionotropic glutamate receptors at extrasynaptic sites, altering synaptic function and leading to a clinically variable neurodevelopmental presentation ranging from untreatable epilepsy to autism spectrum disorder.

Missense variants in RPH3A cause defects in excitatory synaptic function and are associated with a clinically variable neurodevelopmental disorder / L. Pavinato, J. Stanic, M. Barzasi, A. Gurgone, G. Chiantia, V. Cipriani, I. Eberini, L. Palazzolo, M. Diluca, A. Costa, A. Marcantoni, E. Biamino, M. Spada, S.M. Hiatt, W.V. Kelley, L. Vestito, S.M. Sisodiya, G. England Research Consortium, S. Efthymiou, P. Chand, R. Kaiyrzhanov, A. Bruselles, S. Cardaropoli, M. Tartaglia, S. De Rubeis, J.D. Buxbaum, D. Smedley, G.B. Ferrero, M. Giustetto, F. Gardoni, A. Brusco. - In: GENETICS IN MEDICINE. - ISSN 1530-0366. - 25:11(2023 Nov), pp. 100922.1-100922.14. [10.1016/j.gim.2023.100922]

Missense variants in RPH3A cause defects in excitatory synaptic function and are associated with a clinically variable neurodevelopmental disorder

J. Stanic
Secondo
;
M. Barzasi;I. Eberini;L. Palazzolo;M. Diluca;A. Costa;M. Tartaglia;F. Gardoni;
2023

Abstract

Purpose: RPH3A encodes a protein involved in the stabilization of GluN2A subunit of N- methyl-D-aspartate (NMDA)-type glutamate receptors at the cell surface, forming a complex essential for synaptic plasticity and cognition. We investigated the effect of variants in RPH3A in patients with neurodevelopmental disorders. Methods: By using trio-based exome sequencing, GeneMatcher, and screening of 100,000 Genomes Project data, we identified 6 heterozygous variants in RPH3A. In silico and in vitro models, including rat hippocampal neuronal cultures, have been used to characterize the effect of the variants. Results: Four cases had a neurodevelopmental disorder with untreatable epileptic seizures [p.(Gln73His)dn; p.(Arg209Lys); p.(Thr450Ser)dn; p.(Gln508His)], and 2 cases [p.(Arg235Ser); p.(Asn618Ser)dn] showed high-functioning autism spectrum disorder. Using neuronal cultures, we demonstrated that p.(Thr450Ser) and p.(Asn618Ser) reduce the synaptic localization of GluN2A; p.(Thr450Ser) also increased the surface levels of GluN2A. Electrophysiological recordings showed increased GluN2A-dependent NMDA ionotropic glutamate receptor currents for both variants and alteration of postsynaptic calcium levels. Finally, expression of the Rph3AThr450Ser variant in neurons affected dendritic spine morphology. Conclusion: Overall, we provide evidence that missense gain-of-function variants in RPH3A increase GluN2A-containing NMDA ionotropic glutamate receptors at extrasynaptic sites, altering synaptic function and leading to a clinically variable neurodevelopmental presentation ranging from untreatable epilepsy to autism spectrum disorder.
Epilepsy; Excitatory synapse; Neurodevelopmental disorder; Rabphilin; RPH3A;
Settore BIO/14 - Farmacologia
Settore BIO/10 - Biochimica
nov-2023
ago-2023
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/1026641
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