TY - JOUR
T1 - Overexpressing wild-type γ2 subunits rescued the seizure phenotype in Gabrg2+/Q390X Dravet syndrome mice
AU - Huang, Xuan
AU - Zhou, Chengwen
AU - Tian, Mengnan
AU - Kang, Jing Qiong
AU - Shen, Wangzhen
AU - Verdier, Kelienne
AU - Pimenta, Aurea
AU - MacDonald, Robert L.
N1 - Funding Information:
This work was supported by the National Institutes of Health (NIH) R01 National Institute of Neurological Disorders and Stroke (NINDS) NS051590 to RLM; R01 NINDS NS082635 to JQK; American Epilepsy Society (AES) Predoctoral fellowship to XH; and R21NS096483 to CZ, MJG, and RLM. Thanks to Huancheng Dong for his excellent assistance on brain slice preparations.
Publisher Copyright:
Wiley Periodicals, Inc. © 2017 International League Against Epilepsy
PY - 2017/8
Y1 - 2017/8
N2 - Objective: The mutant γ-aminobutyric acid type A (GABAA) receptor γ2(Q390X) subunit (Q351X in the mature peptide) has been associated with the epileptic encephalopathy, Dravet syndrome, and the epilepsy syndrome genetic epilepsy with febrile seizures plus (GEFS+). The mutation generates a premature stop codon that results in translation of a stable truncated and misfolded γ2 subunit that accumulates in neurons, forms intracellular aggregates, disrupts incorporation of γ2 subunits into GABAA receptors, and affects trafficking of partnering α and β subunits. Heterozygous Gabrg2+/Q390X knock-in (KI) mice had reduced cortical inhibition, spike wave discharges on electroencephalography (EEG), a lower seizure threshold to the convulsant drug pentylenetetrazol (PTZ), and spontaneous generalized tonic–clonic seizures. In this proof-of-principal study, we attempted to rescue these deficits in KI mice using a γ2 subunit gene (GABRG2) replacement therapy. Methods: We introduced the GABRG2 allele by crossing Gabrg2+/Q390X KI mice with bacterial artificial chromosome (BAC) transgenic mice overexpressing HA (hemagglutinin)–tagged human γ2HA subunits, and compared GABAA receptor subunit expression by Western blot and immunohistochemical staining, seizure threshold by monitoring mouse behavior after PTZ-injection, and thalamocortical inhibition and network oscillation by slice recording. Results: Compared to KI mice, adult mice carrying both mutant allele and transgene had increased wild-type γ2 and partnering α1 and β2/3 subunits, increased miniature inhibitory postsynaptic current (mIPSC) amplitudes recorded from layer VI cortical neurons, reduced thalamocortical network oscillations, and higher PTZ seizure threshold. Significance: Based on these results we suggest that seizures in a genetic epilepsy syndrome caused by epilepsy mutant γ2(Q390X) subunits with dominant negative effects could be rescued potentially by overexpression of wild-type γ2 subunits.
AB - Objective: The mutant γ-aminobutyric acid type A (GABAA) receptor γ2(Q390X) subunit (Q351X in the mature peptide) has been associated with the epileptic encephalopathy, Dravet syndrome, and the epilepsy syndrome genetic epilepsy with febrile seizures plus (GEFS+). The mutation generates a premature stop codon that results in translation of a stable truncated and misfolded γ2 subunit that accumulates in neurons, forms intracellular aggregates, disrupts incorporation of γ2 subunits into GABAA receptors, and affects trafficking of partnering α and β subunits. Heterozygous Gabrg2+/Q390X knock-in (KI) mice had reduced cortical inhibition, spike wave discharges on electroencephalography (EEG), a lower seizure threshold to the convulsant drug pentylenetetrazol (PTZ), and spontaneous generalized tonic–clonic seizures. In this proof-of-principal study, we attempted to rescue these deficits in KI mice using a γ2 subunit gene (GABRG2) replacement therapy. Methods: We introduced the GABRG2 allele by crossing Gabrg2+/Q390X KI mice with bacterial artificial chromosome (BAC) transgenic mice overexpressing HA (hemagglutinin)–tagged human γ2HA subunits, and compared GABAA receptor subunit expression by Western blot and immunohistochemical staining, seizure threshold by monitoring mouse behavior after PTZ-injection, and thalamocortical inhibition and network oscillation by slice recording. Results: Compared to KI mice, adult mice carrying both mutant allele and transgene had increased wild-type γ2 and partnering α1 and β2/3 subunits, increased miniature inhibitory postsynaptic current (mIPSC) amplitudes recorded from layer VI cortical neurons, reduced thalamocortical network oscillations, and higher PTZ seizure threshold. Significance: Based on these results we suggest that seizures in a genetic epilepsy syndrome caused by epilepsy mutant γ2(Q390X) subunits with dominant negative effects could be rescued potentially by overexpression of wild-type γ2 subunits.
KW - Dravet syndrome
KW - Epileptic encephalopathy
KW - GABA receptors
KW - GABRG2(Q390X) mutation
KW - Gene-replacement therapy
KW - Genetic epilepsies
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U2 - 10.1111/epi.13810
DO - 10.1111/epi.13810
M3 - Article
C2 - 28586508
AN - SCOPUS:85020191583
SN - 0013-9580
VL - 58
SP - 1451
EP - 1461
JO - Epilepsia
JF - Epilepsia
IS - 8
ER -