Structure-Function Analysis of the GlyR α2 Subunit Autism Mutation p.R323L Reveals a Gain-of-Function
Glycine receptors (GlyRs) containing the α2 subunit regulate cortical interneuron migration. Disruption of the GlyR α2 subunit gene (Glra2) in mice leads to disrupted dorsal cortical progenitor homeostasis, leading to a depletion of projection neurons and moderate microcephaly in newborn mice. In hu...
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Frontiers Media S.A.
2017-05-01
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| Series: | Frontiers in Molecular Neuroscience |
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| Online Access: | http://journal.frontiersin.org/article/10.3389/fnmol.2017.00158/full |
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| author | Yan Zhang Thi Nhu Thao Ho Robert J. Harvey Joseph W. Lynch Joseph W. Lynch Angelo Keramidas |
| author_facet | Yan Zhang Thi Nhu Thao Ho Robert J. Harvey Joseph W. Lynch Joseph W. Lynch Angelo Keramidas |
| author_sort | Yan Zhang |
| collection | DOAJ |
| description | Glycine receptors (GlyRs) containing the α2 subunit regulate cortical interneuron migration. Disruption of the GlyR α2 subunit gene (Glra2) in mice leads to disrupted dorsal cortical progenitor homeostasis, leading to a depletion of projection neurons and moderate microcephaly in newborn mice. In humans, rare variants in GLRA2, which is located on the X chromosome, are associated with autism spectrum disorder (ASD) in the hemizygous state in males. These include a microdeletion (GLRA2∆ex8-9) and missense mutations in GLRA2 (p.N109S and p.R126Q) that impair cell-surface expression of GlyR α2, and either abolish or markedly reduce sensitivity to glycine. We report the functional characterization of a third missense variant in GLRA2 (p.R323L), associated with autism, macrocephaly, epilepsy and hypothyroidism in a female proband. Using heterosynapse and macroscopic current recording techniques, we reveal that GlyR α2R323L exhibits reduced glycine sensitivity, but significantly increased inhibitory postsynaptic current (IPSC) rise and decay times. Site-directed mutagenesis revealed that the nature of the amino acid switch at position 323 is critical for impairment of GlyR function. Single-channel recordings revealed that the conductance of α2R323Lβ channels was higher than α2β channels. Longer mean opening durations induced by p.R323L may be due to a change in the gating pathway that enhances the stability of the GlyR open state. The slower synaptic decay times, longer duration active periods and increase in conductance demonstrates that the GlyR α2 p.R323L mutation results in an overall gain of function, and that GlyR α2 mutations can be pathogenic in the heterozygous state in females. |
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| language | English |
| last_indexed | 2024-12-22T17:23:25Z |
| publishDate | 2017-05-01 |
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| spelling | doaj.art-b473e5444d374c85a7f345220674dd912022-12-21T18:18:47ZengFrontiers Media S.A.Frontiers in Molecular Neuroscience1662-50992017-05-011010.3389/fnmol.2017.00158263432Structure-Function Analysis of the GlyR α2 Subunit Autism Mutation p.R323L Reveals a Gain-of-FunctionYan Zhang0Thi Nhu Thao Ho1Robert J. Harvey2Joseph W. Lynch3Joseph W. Lynch4Angelo Keramidas5Queensland Brain Institute, The University of QueenslandBrisbane, QLD, AustraliaQueensland Brain Institute, The University of QueenslandBrisbane, QLD, AustraliaDepartment of Pharmacology, UCL School of PharmacyLondon, United KingdomQueensland Brain Institute, The University of QueenslandBrisbane, QLD, AustraliaSchool of Biomedical Sciences, The University of QueenslandBrisbane, QLD, AustraliaQueensland Brain Institute, The University of QueenslandBrisbane, QLD, AustraliaGlycine receptors (GlyRs) containing the α2 subunit regulate cortical interneuron migration. Disruption of the GlyR α2 subunit gene (Glra2) in mice leads to disrupted dorsal cortical progenitor homeostasis, leading to a depletion of projection neurons and moderate microcephaly in newborn mice. In humans, rare variants in GLRA2, which is located on the X chromosome, are associated with autism spectrum disorder (ASD) in the hemizygous state in males. These include a microdeletion (GLRA2∆ex8-9) and missense mutations in GLRA2 (p.N109S and p.R126Q) that impair cell-surface expression of GlyR α2, and either abolish or markedly reduce sensitivity to glycine. We report the functional characterization of a third missense variant in GLRA2 (p.R323L), associated with autism, macrocephaly, epilepsy and hypothyroidism in a female proband. Using heterosynapse and macroscopic current recording techniques, we reveal that GlyR α2R323L exhibits reduced glycine sensitivity, but significantly increased inhibitory postsynaptic current (IPSC) rise and decay times. Site-directed mutagenesis revealed that the nature of the amino acid switch at position 323 is critical for impairment of GlyR function. Single-channel recordings revealed that the conductance of α2R323Lβ channels was higher than α2β channels. Longer mean opening durations induced by p.R323L may be due to a change in the gating pathway that enhances the stability of the GlyR open state. The slower synaptic decay times, longer duration active periods and increase in conductance demonstrates that the GlyR α2 p.R323L mutation results in an overall gain of function, and that GlyR α2 mutations can be pathogenic in the heterozygous state in females.http://journal.frontiersin.org/article/10.3389/fnmol.2017.00158/fullautism spectrum disorderepilepsyglycine receptorGLRA2GlyR α2 subunit |
| spellingShingle | Yan Zhang Thi Nhu Thao Ho Robert J. Harvey Joseph W. Lynch Joseph W. Lynch Angelo Keramidas Structure-Function Analysis of the GlyR α2 Subunit Autism Mutation p.R323L Reveals a Gain-of-Function Frontiers in Molecular Neuroscience autism spectrum disorder epilepsy glycine receptor GLRA2 GlyR α2 subunit |
| title | Structure-Function Analysis of the GlyR α2 Subunit Autism Mutation p.R323L Reveals a Gain-of-Function |
| title_full | Structure-Function Analysis of the GlyR α2 Subunit Autism Mutation p.R323L Reveals a Gain-of-Function |
| title_fullStr | Structure-Function Analysis of the GlyR α2 Subunit Autism Mutation p.R323L Reveals a Gain-of-Function |
| title_full_unstemmed | Structure-Function Analysis of the GlyR α2 Subunit Autism Mutation p.R323L Reveals a Gain-of-Function |
| title_short | Structure-Function Analysis of the GlyR α2 Subunit Autism Mutation p.R323L Reveals a Gain-of-Function |
| title_sort | structure function analysis of the glyr α2 subunit autism mutation p r323l reveals a gain of function |
| topic | autism spectrum disorder epilepsy glycine receptor GLRA2 GlyR α2 subunit |
| url | http://journal.frontiersin.org/article/10.3389/fnmol.2017.00158/full |
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