BK Channel B4 Subunit in the Dentate Gyrus and Seizures

齿状回中的 BK 通道 B4 亚基和癫痫发作

• 批准号: 7577457
• 负责人: ROBERT BRENNER
• 金额: $ 25.55万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-04-01 至 2012-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7577457
• 关键词: Action Potentials; Affect; Agonist; Animal Model; Antibodies; Apamin; Calcium; Cells; Cyclic AMP; Data; Defect; Disease; Down-Regulation; Drug Design; Electroencephalography; Epilepsy; Exhibits; Feeds; Focal Seizure; Frequencies; Genes; Genetic; Genetic Models; Hippocampus (Brain); Human; Immunohistochemistry; Investigation; Ion Channel; Kinetics; Knock-out; Knockout Mice; Measurement; Mediating; Membrane; Metabotropic Glutamate Receptors; Mus; Mutation; Nature; Nerve; Neurons; Output; Pharmaceutical Preparations; Phosphorylation; Potassium; Potassium Channel; Probability; Property; Proteins; Receptor Signaling; Recruitment Activity; Regulation; Research Personnel; Resistance; Role; Seizures; Signal Transduction; Slice; Synaptic Transmission; Techniques; Temporal Lobe; Temporal Lobe Epilepsy; Testing; Work; base; dentate gyrus; design; gain of function; hypertension control; iberiotoxin; interest; large-conductance calcium-activated potassium channels; metabotropic glutamate receptor 3; mossy fiber; neuronal cell body; neurotransmission; novel; patch clamp; paxilline; programs; protein kinase A kinase; research study; voltage

DESCRIPTION (provided by applicant): Potassium channels have the role of reducing excitability and are pivotal in controlling seizures. The large conductance calcium-activated potassium channels (BK-type channels) have the specialized role of regulating membrane excitability that is coincident with calcium influx. Previously, heterologous co- expression of the pore-forming a subunit with the novel ¿4 accessory subunit was found to produce BK currents with properties of so called neuronal "type II BK channels". The ¿4 subunit confers resistance to iberiotoxin block, slow gating kinetics, and a reduced open probability. In addition, the ¿4 subunit may confer sensitivity to pKA dependent phosphorylation in neurons. We have generated ¿4 gene knockout mice. Our preliminary data provides direct evidence that BK channel assembly with the ¿4 subunit underlies type II BK channels. In the dentate gyrus (DG), knockout cells are more excitable and support high frequency firing. Finally, EEG recording demonstrate that the ¿4 knockout mice exhibit non-convulsive partial seizures. The ¿4 knockout mice may be the first genetic model for non-convulsive temporal lobe epilepsy. Investigation of these mice will allow us the unique opportunity to have a biophysical understanding of the changes in ion channel properties that may underlie this class of epilepsy. Our interest is to understand how a/¿4 subunit BK channels regulate the input/output properties of DG cells, and thereby contribute to resistance of synchronized epileptiform activity that is a property of the DG. Our working hypothesis is that beta4 subunits down-regulates BK channels, resulting in increased calcium influx and reduced excitability by recruitment of SK channels. We have 3 aims. 1) Utilizing patch clamp/slice recordings from DG cells, understand the change in membrane properties that result in increased AP firing in the knockout mice. 2) Determine how the (¿4 subunit modulates sensitivity of BK channels to pKA dependent phosphorylation in the DG, and thereby regulates excitability by metabotropic glutamate receptors 3) Utilize immunohistochemistry and electrophysiological recording techniques to determine the subcellular localization of the ¿4 subunit in nerve terminals and its' contribution to neurotransmission in the mossy fiber terminals. These studies will provide the first understanding of a relatively uncharacterized BK channel subtype and further our understanding of this channels' function in the context of a novel genetic model for epilepsy.

描述（申请人提供）：钾通道具有降低兴奋性的作用，对于控制癫痫发作至关重要。大电导钙激活钾通道（BK 型通道）具有调节膜兴奋性的特殊作用，这与钙内流一致。此前，孔形成亚基与新颖的异源共表达 ¿发现 4 辅助亚基可产生具有所谓神经“II 型 BK 通道”特性的 BK 电流。 4 亚基赋予对伊比利亚毒素阻断的抗性、缓慢的门控动力学以及降低的开放概率。 4 亚基可能赋予神经元对 pKA 依赖性磷酸化的敏感性。 我们已经生成了4 基因敲除小鼠的初步数据提供了 BK 通道组装与 ¿ 4 亚基是 II 型 BK 通道的基础。在齿状回 (DG) 中，敲除细胞更容易兴奋并支持高频放电。最后，脑电图记录表明 ¿ 4只基因敲除小鼠表现出非惊厥性部分性癫痫发作。 4 基因敲除小鼠可能是第一个非惊厥性颞叶癫痫的遗传模型，对这些小鼠的研究将使我们有独特的机会了解可能构成此类癫痫的离子通道特性的变化。 我们的兴趣是了解如何4 亚基 BK 通道调节 DG 细胞的输入/输出特性，从而有助于抵抗同步癫痫样活动，这是 DG 的一个特性。我们的工作假设是 β4 亚基下调 BK 通道，导致钙流入增加和通过招募 SK 通道来降低兴奋性，我们有 3 个目标 1) 利用 DG 细胞的膜片钳/切片记录，了解导致 AP 放电增加的膜特性变化。 2) 确定 (¿4 亚基如何调节 DG 中 BK 通道对 pKA 依赖性磷酸化的敏感性，从而调节代谢型谷氨酸受体的兴奋性 3) 利用免疫组织化学和电生理记录技术来确定 (¿4 亚基) 的亚细胞定位。 ¿神经末梢中的 4 亚基及其对苔藓纤维末梢神经传递的贡献这些研究将首次了解相对未表征的 BK 通道亚型，并进一步了解该通道在癫痫遗传新模型中的功能。 。