A new mouse line with reduced GluA2 Q/R site RNA editing exhibits loss of dendritic spines, hippocampal CA1-neuron loss, learning and memory impairments and NMDA receptor-independent seizure vulnerability.

Publication date: Feb 27, 2020

Calcium (Ca)-permeable AMPA receptors may, in certain circumstances, contribute to normal synaptic plasticity or to neurodegeneration. AMPA receptors are Ca-permeable if they lack the GluA2 subunit or if GluA2 is unedited at a single nucleic acid, known as the Q/R site. In this study, we examined mice engineered with a point mutation in the intronic editing complementary sequence (ECS) of the GluA2 gene, Gria2. Mice heterozygous for the ECS mutation (named GluA2) had a ~?20% reduction in GluA2 RNA editing at the Q/R site. We conducted an initial phenotypic analysis of these mice, finding altered current-voltage relations (confirming expression of Ca-permeable AMPA receptors at the synapse). Anatomically, we observed a loss of hippocampal CA1 neurons, altered dendritic morphology and reductions in CA1 pyramidal cell spine density. Behaviourally, GluA2 mice exhibited reduced motor coordination, and learning and memory impairments. Notably, the mice also exhibited both NMDA receptor-independent long-term potentiation (LTP) and vulnerability to NMDA receptor-independent seizures. These NMDA receptor-independent seizures were rescued by the Ca-permeable AMPA receptor antagonist IEM-1460. In summary, unedited GluA2(Q) may have the potential to drive NMDA receptor-independent processes in brain function and disease. Our study provides an initial characterisation of a new mouse model for studying the role of unedited GluA2(Q) in synaptic and dendritic spine plasticity in disorders where unedited GluA2(Q), synapse loss, neurodegeneration, behavioural impairments and/or seizures are observed, such as ischemia, seizures and epilepsy, Huntington’s disease, amyotrophic lateral sclerosis, astrocytoma, cocaine seeking behaviour and Alzheimer’s disease.

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Konen, L.M., Wright, A.L., Royle, G.A., Morris, G.P., Lau, B.K., Seow, P.W., Zinn, R., Milham, L.T., Vaughan, C.W., and Vissel, B. A new mouse line with reduced GluA2 Q/R site RNA editing exhibits loss of dendritic spines, hippocampal CA1-neuron loss, learning and memory impairments and NMDA receptor-independent seizure vulnerability. 06953. 2020 Mol Brain (13):1.

Concepts Keywords
Alzheimer Synaptic plasticity
AMPA Long-term potentiation
AMPA Receptor NMDA receptor
Amyotrophic Lateral Sclerosis Cell signaling
Antagonist AMPA receptor
Astrocytoma Neurophysiology
Brain Neuroplasticity
CA1 Ionotropic glutamate receptors
Cocaine Neuroscience
Dendritic Spine Branches of biology
Dendritic Spines Seizures
Epilepsy Spine plasticity disorders
Gene
GluA2
Gria2
Heterozygous
Hippocampal
Huntington
IEM
Ischemia
Long Term Potentiation
LTP
Memory
Mice
Morphology
Motor Coordination
Mutation
Neurodegeneration
Neuron
Neurons
NMDA Receptor
Nucleic Acid
Phenotypic
Plasticity
Point Mutation
Receptors
Seizure
Seizures
Synapse
Synaptic
Synaptic Plasticity
Voltage

Semantics

Type Source Name
drug DRUGBANK Calcium
disease MESH point mutation
pathway KEGG Long-term potentiation
disease MESH seizures
disease MESH ischemia
disease MESH epilepsy
disease MESH amyotrophic lateral sclerosis
disease MESH astrocytoma
drug DRUGBANK Cocaine

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