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Mechanisms underlying the epileptic phenotype associated with the alpha-1 A322D mutation in the GABA-A receptor Bradley, Clarrisa Ann
Abstract
Epilepsy is a common neurological disorder with a strong hereditary component. A mutation in the α1 subunit (A322D) of the GABA-A receptor is responsible for juvenile myoclonic epilepsy in a large Canadian family. Previous work has identified that this mutation affects the function of GABA-A receptors, expressed in HEK293 cells. Here I have examined the underlying mechanisms of this dysfunction and shown that the mutation reduces the cell surface expression of the GABA-A receptor, promotes association with the endoplasmic reticulum chaperone calnexin, enhances degradation and accelerates the degradation rate of the subunits approximately 2.5 fold. I have also found that the mutation causes the receptor to be degraded by a lysosomal-dependent process. Furthermore, I find that the mutation results in receptors that are inserted into the plasma membrane but are more rapidly endocytosed by a dynamin and caveolin-dependent mechanism. These results suggest that the mutant subunit can form trafficking-competent receptors that have a shorter lifetime on the plasma membrane. Collectively, my results strongly implicate defects in both the biogenesis and trafficking of the GABA-A receptors, as part of the mechanistic basis for the epileptic phenotype observed.
Item Metadata
Title |
Mechanisms underlying the epileptic phenotype associated with the alpha-1 A322D mutation in the GABA-A receptor
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2010
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Description |
Epilepsy is a common neurological disorder with a strong hereditary component. A mutation in the α1 subunit (A322D) of the GABA-A receptor is responsible for juvenile myoclonic epilepsy in a large Canadian family. Previous work has identified that this mutation affects the function of GABA-A receptors, expressed in HEK293 cells. Here I have examined the underlying mechanisms of this dysfunction and shown that the mutation reduces the cell surface expression of the GABA-A receptor, promotes association with the endoplasmic reticulum chaperone calnexin, enhances degradation and accelerates the degradation rate of the subunits approximately 2.5 fold. I have also found that the mutation causes the receptor to be degraded by a lysosomal-dependent process. Furthermore, I find that the mutation results in receptors that are inserted into the plasma membrane but are more rapidly endocytosed by a dynamin and caveolin-dependent mechanism. These results suggest that the mutant subunit can form trafficking-competent receptors that have a shorter lifetime on the plasma membrane. Collectively, my results strongly implicate defects in both the biogenesis and trafficking of the GABA-A receptors, as part of the mechanistic basis for the epileptic phenotype observed.
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Genre | |
Type | |
Language |
eng
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Date Available |
2010-08-16
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Provider |
Vancouver : University of British Columbia Library
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Rights |
Attribution-NonCommercial-NoDerivatives 4.0 International
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DOI |
10.14288/1.0071142
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2010-11
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Campus | |
Scholarly Level |
Graduate
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Rights URI | |
Aggregated Source Repository |
DSpace
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Rights
Attribution-NonCommercial-NoDerivatives 4.0 International