Understanding ANK3-associated epileptic encephalopathies

发育性和癫痫性脑病（DEE）是严重的癫痫综合征，表现在婴儿期 或幼儿期，其特征是顽固性癫痫发作，神经和行为缺陷，以及高 癫痫猝死（SUDEP）虽然大多数DEE与基因变异有关， 编码离子通道，特别是电压门控钠（NaV）和钾（KV）通道，DEE-连接 非离子通道基因的变异可能对疾病的病因学提供重要的见解。最近，整个 我们在中国北京大学的同事对DEE患者的外显子组测序发现了不确定的 在ANK 3中的VUS显著性（VUS），表明离子通道定位的缺陷可能有助于疾病 机制等大量的文献表明，由ANK 3基因编码的anklycer-G， 在电压门控离子通道定位于关键神经元质膜中的基本作用 子域，包括轴突起始段（AIS）和Ranvier节点，它们是动作电位的位点 (AP)启动和传播。最近，我们发现了新的功能，为anke-G在 调节抑制性突触和控制神经元兴奋性。然而， ANK 3和癫痫之间的联系尚不完全清楚。我们工作的长期目标是了解 强直-G功能障碍如何导致神经系统疾病（如DEE）的病因。的目的 应用是使用敲除和拯救策略来了解细胞和电生理效应 在北京大学DEE队列中鉴定的变异。我们的中心假设是DEE相关的ANK 3 变异体在控制电压门控和配体门控离子通道的定位和功能中影响anke-G功能 导致锥体细胞功能障碍，导致DEE的病理生理学。我们将测试我们的假设 通过追求两个特定的目的：1）了解人DEE相关ANK 3变体对锚蛋白的影响， G介导的离子通道定位。2)为了确定ANK 3 DEE的电生理后果， 相关变种ANK 3与癫痫之间的联系机制尚不完全 理解，但最近在中国DEE患者队列中发现的VUS表明了一种新的DEE 机制这项工作的结果将对理解锚蛋白- G调节神经元的兴奋性以及抗G蛋白功能丧失如何导致复杂的神经系统疾病 疾病，如DEE。大多数已发表的研究DEE机制的工作都集中在病人身上。 离子通道基因的变异。然而，针对离子通道扰动的治疗策略 功能已被证明对许多DEE无效。我们的方法可能会产生新的目标，这可以作为一个 指导制定创新的治疗策略，以治疗DEE和其他可能的特发性癫痫。 此外，这些研究的结果可能揭示以前未被认识到的功能，AnkG在 神经传递

Developmental and epileptic encephalopathies (DEEs) are severe epilepsy syndromes that manifest in infancy or early childhood and are characterized by intractable seizures, neurological and behavioral deficits, and a high risk of Sudden Unexpected Death in Epilepsy (SUDEP). While most DEEs are linked to variants in genes encoding ion channels, especially that of voltage-gated sodium (NaV) and potassium (KV) channels, DEE-linked variants in non-ion-channel genes may provide important insights into the etiology of disease. Recently, whole exome sequencing of DEE patients by our Peking University colleagues in China identified variants of uncertain significance (VUS) in ANK3, suggesting that deficits in ion channel localization may contribute to disease mechanisms. A large body of literature has shown that ankyrin-G, encoded by the ANK3 gene, plays a fundamental role in the localization of voltage-gated ion channels to critical neuronal plasma membrane subdomains, including the axon initial segment (AIS) and nodes of Ranvier, which are the sites of action potential (AP) initiation and propagation, respectively. Recently, we have discovered novel functions for ankyrin-G in the regulation of inhibitory synapses and control of neuronal excitability. However, the mechanisms underlying the link between ANK3 and epilepsy are incompletely understood. The long-term goal of our work is to understand how ankyrin-G dysfunction contributes to the etiology of neurological disorders, like DEE. The objective of this application is to use a knockout and rescue strategy to understand the cellular and electrophysiological effects of variants identified in the Peking University DEE cohort. Our central hypothesis is that DEE-associated ANK3 variants affect ankyrin-G function in controlling localization and function of voltage- and ligand-gated ion channels resulting in pyramidal cell dysfunction, contributing to the pathophysiology of DEE. We will test our hypothesis by pursuing two Specific Aims: 1) To understand the effects of human DEE-associated ANK3 variants on ankyrin- G-mediated ion channel localization. 2) To determine the electrophysiological consequences of ANK3 DEE- associated variants. The mechanisms underlying the link between ANK3 and epilepsy are incompletely understood, yet the recently discovered VUS from the DEE patient cohort in China suggest a novel DEE mechanism. The results of this work will have an important positive impact on the understanding of how ankyrin- G regulates neuronal excitability and how ankyrin-G loss-of-function contributes to complex neurological disorders, such as DEE. Most of the published work investigating DEE mechanisms has focused on patient variants within ion channel genes. However, treatment strategies targeted against perturbations in ion channel function have proven ineffective for many DEEs. Our approach may yield novel targets, which could serve as a guide to develop innovative therapeutic strategies to treat DEE and possibly other idiopathic forms of epilepsy. In addition, the results of these studies may uncover previously unappreciated functions of AnkG in neurotransmission.