Towards the development of a novel treatment for epilepsy

描述(申请人提供)：电压门控钠通道SCN1A、SCN2A、SCN3A和SCN8A是中枢神经系统(CNS)神经元兴奋性的关键调节因子。SCN1A、SCN2A和SCN3A基因突变与几种癫痫亚型有关，包括全身性癫痫伴热性惊厥(GEFS+)和婴儿期严重肌阵挛癫痫(SMEI)，这是一种以难治性癫痫、智力低下和共济失调为特征的衰弱儿童疾病。与之形成鲜明对比的是，我们在携带Scn8a基因突变的小鼠中观察到癫痫阈值升高。此外，我们能够通过基因改变Scn8a的活性来恢复建立GEFS+和SMEI模型的Scn1a突变体的正常癫痫阈值和寿命。基于这些观察，我们假设神经元的兴奋性可以通过选择性地降低Scn8a的表达水平来调节，从而为癫痫的治疗提供了一种潜在的新途径。由于目前的抗癫痫药物不能选择性地靶向SCN8A，我们将评估通过体内shRNA干扰策略选择性降低Scn8a表达水平来改变神经元兴奋性的可能性。这将通过两个具体目标来实现。第一个目的是构建针对Scn8a的腺相关病毒(AAV)短发夹状RNA(ShRNA)表达载体(AAV-sh8a)。将该试剂输送到小鼠海马区将得到优化，以实现最大限度地下调Scn8a的表达。在第二个目的中，我们将评估AAV-sh8a改善SMEI小鼠模型癫痫表型的能力。如果成功，这项R21原则证明提案将为难治性癫痫亚型的治疗开辟一个重要的新方向。公共卫生相关性：尽管在抗癫痫药物开发方面取得了进展，但仍有20%-40%的癫痫患者无法实现充分的癫痫发作控制或对治疗完全没有反应。在这项原则验证研究中，我们将开发和测试一种潜在的治疗严重癫痫的新策略。如果成功，这项研究可能会为治疗对当前药物无效的癫痫亚型提供新的希望。

DESCRIPTION (provided by applicant): The voltage-gated sodium channels SCN1A, SCN2A, SCN3A, and SCN8A are key regulators of neuronal excitability in the central nervous system (CNS). Mutations in SCN1A, SCN2A, and SCN3A are associated with several epilepsy subtypes, including generalized epilepsy with febrile seizures plus (GEFS+) and severe myoclonic epilepsy of infancy (SMEI), a debilitating childhood disorder characterized by refractory seizures, mental retardation, and ataxia. In striking contrast, we have observed elevated seizure thresholds in mice with mutations in Scn8a. Furthermore, we were able to restore normal seizure thresholds and lifespans in Scn1a mutants that model GEFS+ and SMEI by genetically altering the activity of Scn8a. Based on these observations, we hypothesize that neuronal excitability can be modulated by selectively reducing the expression level of Scn8a, thereby providing a potentially new approach to the treatment of epilepsy. Since current anti- epilepsy drugs (AEDs) cannot selectively target SCN8A, we will evaluate the possibility of altering neuronal excitability by selectively reducing the expression level of Scn8a using an in vivo shRNA interference strategy. This will be accomplished in two specific aims. In the first aim we will generate an adeno-associated virus (AAV) short-hairpin RNA (shRNA) expression vector against Scn8a (AAV- sh8a). The delivery of this reagent into the mouse hippocampus will be optimized to achieve maximum knockdown of Scn8a expression. In the second aim we will evaluate the ability of AAV-sh8a to ameliorate the seizure phenotype in a mouse model of SMEI. If successful, this proof-of-principle R21 proposal would open up an important new direction for the treatment of refractory epilepsy subtypes. PUBLIC HEALTH RELEVANCE: Despite advances in anti-epilepsy drug development, 20-40% of epilepsy patients still do not achieve adequate seizure control or do not respond to treatment at all. In this proof-of-principle study, we will develop and test a potential new strategy for the treatment of severe epilepsy. If successful, this study may offer new hope for the treatment of epilepsy subtypes that do not respond to current medications.