Cellular physiology of epilepsy-associated KCNQ2 channels

描述（由申请人提供）：KCNQ通道家族包括五个基因，称为Kcnq 1 -5。大多数家庭成员都需要神经或心血管系统的正常功能，因为Kcnq基因的功能缺失突变导致LQTS综合征（Kcnq 1），进行性听力损失（Kcnq 4）和良性家族性新生儿惊厥（BFNC），儿科癫痫（Kcnq 2，Kcnq 3）。KCNQ 2/3异聚体通道被认为介导M电流，一种控制CNS神经元兴奋性的亚阈值激活钾电导。然而，与KCNQ 3通道不同的是，超过90%的与BFNC相关的突变被定位到Kcnq 2基因位点，Kcnq 2基因敲除小鼠在出生后24小时内死亡。因此，Kcnq 2可能是大脑中主要的KCNQ亚基，也可能在其他生理过程中发挥独特的作用。我们的长期目标是了解KCNQ通道的体内功能以及这些通道的突变如何导致癫痫发生。该项目的总体目标是确定KCNQ 2通道在控制内在神经元兴奋性中的作用。为了实现我们的目标，我们将结合联合收割机药理学，蛋白质工程，遗传学和电生理学。使用这些方法，我们将首先使用最近确定的KCNQ 2特异性抑制剂建立KCNQ 2通道对整个发育过程中M电流的功能贡献。随后，我们将使用功能获得突变和新药理学来测试KCNQ 2通道是否是大脑中多种电导的基础。最后，我们将使用KCNQ 2条件性敲除小鼠测试KCNQ 2通道在调节静息和活性膜特性中的作用。这些研究将使用电流钳和电压钳记录在小鼠脑切片中进行。我们将使用海马体作为模型脑区，因为它与癫痫、学习和记忆有关。这些研究的结果将提供对一个重要的钾通道的深入了解，该通道在限制大脑中未经检查的神经元活动和癫痫发作中起着重要作用。

DESCRIPTION (provided by applicant): The KCNQ channel family includes five genes, known as Kcnq1-5. Most family members are required for proper function of either the nervous or cardiovascular system as loss of function mutations in Kcnq genes lead to LQTS syndrome (Kcnq1), progressive hearing loss (Kcnq4) and benign familial neonatal convulsions (BFNC), a pediatric epilepsy (Kcnq2, Kcnq3). KCNQ2/3 heteromeric channels are thought to mediate the M-current, a sub-threshold activating potassium conductance that controls the excitability of CNS neurons. However, unlike KCNQ3 channels, more than 90% of mutations related to the BFNC are mapped to the Kcnq2 gene locus and Kcnq2 knockout mice die within 24 hours after birth. Thus, Kcnq2 may either be the primary KCNQ subunit in the brain or it may play a unique role in additional physiological processes. Our long-term goal is to understand the in vivo functions of KCNQ channels and how mutations in these channels lead to epileptogenesis. The overall goal of this project is to determine the role of KCNQ2 channels in controlling intrinsic neuronal excitability. To achieve our objective we will combine pharmacology, protein engineering, genetics, and electrophysiology. Using these approaches we will first establish the functional contribution of KCNQ2 channels to the M-current across development using a recently identified KCNQ2-specific inhibitor. We will subsequently test whether KCNQ2 channels underlie multiple conductances in the brain using gain-of-function mutations and novel pharmacology. Lastly, we will test the role of KCNQ2 channels in regulating resting and active membrane properties using Kcnq2 conditional knockout mice. These studies will be conducted in mouse brain slices using current- and voltage-clamp recordings. We will use hippocampus as a model brain area because it is implicated in epilepsy and learning and memory. The results from these studies will provide insight into an important potassium channel that plays a fundamental role in limiting unchecked neuronal activity and seizures in the brain.