title: Mechanistic Insight into NMDA Receptor Dysregulation by Rare Variants in the GluN2A and GluN2B Agonist Binding Domains.
abstract: Epilepsy and intellectual disability are associated with rare variants in the GluN2A and GluN2B (encoded by GRIN2A and GRIN2B) subunits of the N-methyl-D-aspartate receptor (NMDAR), a ligand-gated ion channel with essential roles in brain development and function. By assessing genetic variation across GluN2 domains, we determined that the agonist binding domain, transmembrane domain, and the linker regions between these domains were particularly intolerant to functional variation. Notably, the agonist binding domain of GluN2B exhibited significantly more variation intolerance than that of GluN2A. To understand the ramifications of missense variation in the agonist binding domain, we investigated the mechanisms by which 25 rare variants in the GluN2A and GluN2B agonist binding domains dysregulated NMDAR activity. When introduced into recombinant human NMDARs, these rare variants identified in individuals with neurologic disease had complex, and sometimes opposing, consequences on agonist binding, channel gating, receptor biogenesis, and forward trafficking. Our approach combined quantitative assessments of these effects to estimate the overall impact on synaptic and non-synaptic NMDAR function. Interestingly, similar neurologic diseases were associated with both gain- and loss-of-function variants in the same gene. Most rare variants in GluN2A were associated with epilepsy, whereas GluN2B variants were associated with intellectual disability with or without seizures. Finally, discerning the mechanisms underlying NMDAR dysregulation by these rare variants allowed investigations of pharmacologic strategies to correct NMDAR function.
authors.affiliation: Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA.
authors.forename: Sharon A
authors.initials: SA
authors.lastname: Swanger
authors.affiliation: Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA.
authors.forename: Wenjuan
authors.initials: W
authors.lastname: Chen
authors.affiliation: Department of Chemistry, Emory University, Atlanta, GA 30322, USA.
authors.forename: Gordon
authors.initials: G
authors.lastname: Wells
authors.affiliation: Department of Chemistry, Emory University, Atlanta, GA 30322, USA.
authors.forename: Pieter B
authors.initials: PB
authors.lastname: Burger
authors.affiliation: Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA.
authors.forename: Anel
authors.initials: A
authors.lastname: Tankovic
authors.affiliation: Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA.
authors.forename: Subhrajit
authors.initials: S
authors.lastname: Bhattacharya
authors.affiliation: Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA; Department of Chemistry, Emory University, Atlanta, GA 30322, USA.
authors.forename: Katie L
authors.initials: KL
authors.lastname: Strong
authors.affiliation: Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA.
authors.forename: Chun
authors.initials: C
authors.lastname: Hu
authors.affiliation: Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Kusumoto
authors.affiliation: Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Undiagnosed Diseases Network, National Human Genome Research Institute, NIH, Bethesda, MD 20892, USA.
authors.forename: David R
authors.initials: DR
authors.lastname: Adams
authors.affiliation: Departments of Pediatrics and Neurology, Northwestern University Feinberg School of Medicine and Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL 60611, USA.
authors.forename: John J
authors.initials: JJ
authors.lastname: Millichap
authors.affiliation: Department of Medicine, The University of Melbourne, Austin Health and Royal Melbourne Hospital, Melbourne, VIC 3050, Australia.
authors.forename: Slavé
authors.initials: S
authors.lastname: Petrovski
authors.affiliation: Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA; Center for Functional Evaluation of Rare Variants (CFERV), Emory University School of Medicine, Atlanta, GA 30322, USA. Electronic address: strayne@emory.edu.
authors.forename: Stephen F
authors.initials: SF
authors.lastname: Traynelis
authors.affiliation: Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA; Center for Functional Evaluation of Rare Variants (CFERV), Emory University School of Medicine, Atlanta, GA 30322, USA. Electronic address: hyuan@emory.edu.
authors.forename: Hongjie
authors.initials: H
authors.lastname: Yuan
mesh_terms: D004827:Epilepsy / Q000235:genetics; D059472:Exome / Q000235:genetics; D018698:Glutamic Acid / Q000378:metabolism; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics; D008958:Models, Molecular; D020125:Mutation, Missense; D009474:Neurons / Q000378:metabolism; D011485:Protein Binding / Q000235:genetics; D000072417:Protein Domains / Q000235:genetics; D021381:Protein Transport; D016194:Receptors, N-Methyl-D-Aspartate / Q000819:agonists* / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D012640:Seizures / Q000235:genetics
chemical_list: D018698:Glutamic Acid; D016194:Receptors, N-Methyl-D-Aspartate; C121001:NR2B NMDA receptor