Towards the development of a novel treatment for epilepsy

描述（由申请人提供）：电压门控钠通道SCN 1A、SCN 2A、SCN 3A和SCN 8A是中枢神经系统（CNS）神经元兴奋性的关键调节因子。SCN 1A、SCN 2A和SCN 3A中的突变与几种癫痫亚型相关，包括全身性癫痫伴热性惊厥+（GEFS+）和婴儿期严重肌阵挛性癫痫（SMEI），这是一种以难治性癫痫发作、精神发育迟滞和共济失调为特征的衰弱性儿童疾病。与此形成鲜明对比的是，我们在Scn 8a突变的小鼠中观察到癫痫发作阈值升高。此外，我们能够通过遗传改变Scn 8a的活性来恢复Scn 1a突变体的正常癫痫发作阈值和寿命，这些突变体模拟GEFS+和SMEI。基于这些观察结果，我们假设神经元兴奋性可以通过选择性地降低Scn 8a的表达水平来调节，从而提供了一种潜在的治疗癫痫的新方法。由于目前的抗癫痫药物（AED）不能选择性靶向SCN 8A，我们将评估通过使用体内shRNA干扰策略选择性降低SCN 8a的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。在第一个目标中，我们将产生针对Scn 8a的腺相关病毒（AAV）短发夹RNA（shRNA）表达载体（AAV-sh 8a）。将该试剂递送到小鼠海马中进行优化以实现Scn 8a表达的最大敲低。在第二个目标中，我们将评估AAV-sh 8a改善SMEI小鼠模型中癫痫发作表型的能力。如果成功的话，R21的原理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：尽管抗癫痫药物开发取得了进展，但仍有20-40%的癫痫患者无法充分控制癫痫发作或对治疗完全没有反应。在这项原理验证研究中，我们将开发和测试一种治疗严重癫痫的潜在新策略。如果成功，这项研究可能为治疗对目前药物无反应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.