Pathophysiology of and therapeutic options for a GABRA1 variant linked to epileptic encephalopathy
Abstract We report the identification of a de novo GABRA1 (R214C) variant in a child with epileptic encephalopathy (EE), describe its functional characterization and pathophysiology, and evaluate its potential therapeutic options. The GABRA1 (R214C) variant was identified using whole exome sequencin...
| Main Authors: | , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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BMC
2019-11-01
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| Series: | Molecular Brain |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1186/s13041-019-0513-9 |
| _version_ | 1818694739994607616 |
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| author | Yun-Fei Bai Michelle Chiu Elizabeth S. Chan Peter Axerio-Cilies Jie Lu Linda Huh Mary B. Connolly Ilaria Guella Matthew J. Farrer Zhi-Qing David Xu Lidong Liu Michelle Demos Yu Tian Wang |
| author_facet | Yun-Fei Bai Michelle Chiu Elizabeth S. Chan Peter Axerio-Cilies Jie Lu Linda Huh Mary B. Connolly Ilaria Guella Matthew J. Farrer Zhi-Qing David Xu Lidong Liu Michelle Demos Yu Tian Wang |
| author_sort | Yun-Fei Bai |
| collection | DOAJ |
| description | Abstract We report the identification of a de novo GABRA1 (R214C) variant in a child with epileptic encephalopathy (EE), describe its functional characterization and pathophysiology, and evaluate its potential therapeutic options. The GABRA1 (R214C) variant was identified using whole exome sequencing, and the pathogenic effect of this mutation was investigated by comparing wild-type (WT) α1 and R214C α1 GABAA receptor-expressing HEK cells. GABA-evoked currents in these cells were recorded using whole-cell, outside-out macro-patch and cell-attached single-channel patch-clamp recordings. Changes to surface and total protein expression levels of WT α1 and R214C α1 were quantified using surface biotinylation assay and western blotting, respectively. Finally, potential therapeutic options were explored by determining the effects of modulators, including diazepam, insulin, and verapamil, on channel gating and receptor trafficking of WT and R214C GABAA receptors. We found that the GABRA1 (R214C) variant decreased whole-cell GABA-evoked currents by reducing single channel open time and both surface and total GABAA receptor expression levels. The GABA-evoked currents in R214C GABAA receptors could only be partially restored with benzodiazepine (diazepam) and insulin. However, verapamil treatment for 24 h fully restored the function of R214C mutant receptors, primarily by increasing channel open time. We conclude that the GABRA1 (R214C) variant reduces channel activity and surface expression of mutant receptors, thereby contributing to the pathogenesis of genetic EE. The functional restoration by verapamil suggests that it is a potentially new therapeutic option for patients with the R214C variant and highlights the value of precision medicine in the treatment of genetic EEs. |
| first_indexed | 2024-12-17T13:34:22Z |
| format | Article |
| id | doaj.art-05079710b492409489c8147725986750 |
| institution | Directory Open Access Journal |
| issn | 1756-6606 |
| language | English |
| last_indexed | 2024-12-17T13:34:22Z |
| publishDate | 2019-11-01 |
| publisher | BMC |
| record_format | Article |
| series | Molecular Brain |
| spelling | doaj.art-05079710b492409489c81477259867502022-12-21T21:46:28ZengBMCMolecular Brain1756-66062019-11-0112111710.1186/s13041-019-0513-9Pathophysiology of and therapeutic options for a GABRA1 variant linked to epileptic encephalopathyYun-Fei Bai0Michelle Chiu1Elizabeth S. Chan2Peter Axerio-Cilies3Jie Lu4Linda Huh5Mary B. Connolly6Ilaria Guella7Matthew J. Farrer8Zhi-Qing David Xu9Lidong Liu10Michelle Demos11Yu Tian Wang12Djavad Mowafaghian Centre for Brain Health and Department of Medicine, University of British ColumbiaDivision of Neurology, Department of Paediatrics, BC Children’s Hospital, University of British ColumbiaDjavad Mowafaghian Centre for Brain Health and Department of Medicine, University of British ColumbiaDjavad Mowafaghian Centre for Brain Health and Department of Medicine, University of British ColumbiaDjavad Mowafaghian Centre for Brain Health and Department of Medicine, University of British ColumbiaDivision of Neurology, Department of Paediatrics, BC Children’s Hospital, University of British ColumbiaDivision of Neurology, Department of Paediatrics, BC Children’s Hospital, University of British ColumbiaCentre for Applied Neurogenetics, University of British ColumbiaCentre for Applied Neurogenetics, University of British ColumbiaDepartment of Neurobiology, Beijing Key Laboratory of Neural Regeneration and Repair, Beijing Laboratory of Brain Disorders (Ministry of Science and Technology), Beijing Institute for Brain Disorders, Capital Medical UniversityDjavad Mowafaghian Centre for Brain Health and Department of Medicine, University of British ColumbiaDivision of Neurology, Department of Paediatrics, BC Children’s Hospital, University of British ColumbiaDjavad Mowafaghian Centre for Brain Health and Department of Medicine, University of British ColumbiaAbstract We report the identification of a de novo GABRA1 (R214C) variant in a child with epileptic encephalopathy (EE), describe its functional characterization and pathophysiology, and evaluate its potential therapeutic options. The GABRA1 (R214C) variant was identified using whole exome sequencing, and the pathogenic effect of this mutation was investigated by comparing wild-type (WT) α1 and R214C α1 GABAA receptor-expressing HEK cells. GABA-evoked currents in these cells were recorded using whole-cell, outside-out macro-patch and cell-attached single-channel patch-clamp recordings. Changes to surface and total protein expression levels of WT α1 and R214C α1 were quantified using surface biotinylation assay and western blotting, respectively. Finally, potential therapeutic options were explored by determining the effects of modulators, including diazepam, insulin, and verapamil, on channel gating and receptor trafficking of WT and R214C GABAA receptors. We found that the GABRA1 (R214C) variant decreased whole-cell GABA-evoked currents by reducing single channel open time and both surface and total GABAA receptor expression levels. The GABA-evoked currents in R214C GABAA receptors could only be partially restored with benzodiazepine (diazepam) and insulin. However, verapamil treatment for 24 h fully restored the function of R214C mutant receptors, primarily by increasing channel open time. We conclude that the GABRA1 (R214C) variant reduces channel activity and surface expression of mutant receptors, thereby contributing to the pathogenesis of genetic EE. The functional restoration by verapamil suggests that it is a potentially new therapeutic option for patients with the R214C variant and highlights the value of precision medicine in the treatment of genetic EEs.http://link.springer.com/article/10.1186/s13041-019-0513-9GABA a receptorEpileptic encephalopathyMutationTherapeutic options |
| spellingShingle | Yun-Fei Bai Michelle Chiu Elizabeth S. Chan Peter Axerio-Cilies Jie Lu Linda Huh Mary B. Connolly Ilaria Guella Matthew J. Farrer Zhi-Qing David Xu Lidong Liu Michelle Demos Yu Tian Wang Pathophysiology of and therapeutic options for a GABRA1 variant linked to epileptic encephalopathy Molecular Brain GABA a receptor Epileptic encephalopathy Mutation Therapeutic options |
| title | Pathophysiology of and therapeutic options for a GABRA1 variant linked to epileptic encephalopathy |
| title_full | Pathophysiology of and therapeutic options for a GABRA1 variant linked to epileptic encephalopathy |
| title_fullStr | Pathophysiology of and therapeutic options for a GABRA1 variant linked to epileptic encephalopathy |
| title_full_unstemmed | Pathophysiology of and therapeutic options for a GABRA1 variant linked to epileptic encephalopathy |
| title_short | Pathophysiology of and therapeutic options for a GABRA1 variant linked to epileptic encephalopathy |
| title_sort | pathophysiology of and therapeutic options for a gabra1 variant linked to epileptic encephalopathy |
| topic | GABA a receptor Epileptic encephalopathy Mutation Therapeutic options |
| url | http://link.springer.com/article/10.1186/s13041-019-0513-9 |
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