Targeted knockout of GABA-A receptor gamma 2 subunit provokes transient light-induced reflex seizures in zebrafish larvae
Targeted knockout of GABA-A receptor gamma 2 subunit provokes transient light-induced reflex seizures in zebrafish larvae
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DOI：
10.1242/dmm.040782
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发表时间：
2019-11-01
影响因子：
4.3
通讯作者：
Samarut, Eric
中科院分区：
文献类型：
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作者：
Liao, Meijiang;Kundap, Uday;Samarut, Eric
癫痫是一种常见的原发性神经系统疾病，其特征在于患者经历癫痫发作的慢性倾向，癫痫发作是由过度的超同步大脑活动引起的异常身体运动或认知状态。癫痫已被发现有许多病因，虽然约三分之二的癫痫被经典地认为是特发性的，但现在大多数被认为是遗传起源。参与γ-氨基丁酸（GABA）介导的抑制性神经传递的基因突变与广泛的癫痫综合征有关。例如，GABA-A受体γ 2亚基基因（GABRG 2）的突变与人类失神癫痫和热性惊厥有关。GABRG 2功能丧失的几种啮齿动物模型描述了该疾病的临床特征;然而，仍然需要更适合于发病研究和高通量筛选目的的替代遗传模型。在这种情况下，我们产生了gabrg 2敲除（KO）斑马鱼模型（我们称之为R23 X），显示光/暗诱导的反射性癫痫发作。通过高分辨率的体内脑钙成像，我们发现这种表型与神经元活动的广泛增加有关，抗癫痫药物丙戊酸可以有效缓解这种增加。此外，这些癫痫发作只发生在幼虫阶段，但在1周龄后消失。有趣的是，我们的全转录组分析表明，gabrg 2 KO不会改变幼虫大脑中基因的表达。因此，gabrg 2（-/-）斑马鱼是一种新的早期癫痫的体内遗传模型，为研究癫痫发作和进一步的药物筛选试验打开了新的大门。
Epilepsy is a common primary neurological disorder characterized by the chronic tendency of a patient to experience epileptic seizures, which are abnormal body movements or cognitive states that result from excessive, hypersynchronous brain activity. Epilepsy has been found to have numerous etiologies and, although about two-thirds of epilepsies were classically considered idiopathic, the majority of those are now believed to be of genetic origin. Mutations in genes involved in gamma-aminobutyric acid (GABA)-mediated inhibitory neurotransmission have been associated with a broad range of epilepsy syndromes. Mutations in the GABA-A receptor gamma 2 subunit gene (GABRG2), for example, have been associated with absence epilepsy and febrile seizures in humans. Several rodent models of GABRG2 loss of function depict clinical features of the disease; however, alternative genetic models more amenable for the study of ictogenesis and for high-throughput screening purposes are still needed. In this context, we generated a gabrg2 knockout (KO) zebrafish model (which we called R23X) that displayed light/dark-induced reflex seizures. Through high-resolution in vivo calcium imaging of the brain, we showed that this phenotype is associated with widespread increases in neuronal activity that can be effectively alleviated by the anti-epileptic drug valproic acid. Moreover, these seizures only occur at the larval stages but disappear after 1 week of age. Interestingly, our whole-transcriptome analysis showed that gabrg2 KO does not alter the expression of genes in the larval brain. As a result, the gabrg2(-/-) zebrafish is a novel in vivo genetic model of early epilepsies that opens new doors to investigate ictogenesis and for further drug-screening assays.