The cellular basis of Episodic Ataxia/Myokemia type1

阵发性共济失调/肌瘤 1 型的细胞基础

• 批准号: 7616371
• 负责人: Forrest Davis
• 金额: $ 2.99万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-12-01 至 2009-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7616371
• 关键词: Acetazolamide; Action Potentials; Adrenergic Agents; Adrenergic Receptor; Affect; Animal Model; Ataxia; Carbonic Anhydrase Inhibitors; Cells; Cerebellar Ataxia; Cerebellar Nuclei; Cerebellar cortex structure; Cerebellum; Characteristics; Chromosome Pairing; Code; Depth; Disease; Disease model; Electrophysiology (science); Event; Exhibits; Failure; Fire - disasters; Frequencies; Functional disorder; Genes; Genotype; Goals; Grant; Human; Image; Individual; Inherited; Interneurons; Laboratories; Localized; Measures; Missense Mutation; Motor; Movement; Mus; Mutant Strains Mice; Mutation; Myoepithelial cell; Myokymia; Output; Patients; Pattern; Performance; Pharmaceutical Preparations; Phenotype; Photons; Physiological; Picrotoxin; Play; Point Mutation; Potassium Channel; Presynaptic Terminals; Probability; Process; Purkinje Cells; Role; Source; Stress; Synapses; Syndrome; Variant; Voltage-Gated Potassium Channel; Work; adrenergic; base; delayed rectifier potassium channel; gamma-Aminobutyric Acid; homologous recombination; human disease; in vivo; insight; motor control; motor deficit; mouse model; mutant; neurotransmitter release; novel; presynaptic; synaptic inhibition; transmission process; voltage

DESCRIPTION (provided by applicant): The overall goal of this proposal is to determine how a missense mutation in the voltage-gated potassium channel subunit, Kv1.1 alters cerebellar out-put and results in Episodic Ataxia type 1 (EA1). V408A is one of the human EA1 mutations, and results in Kv1.1 channels with an unstable open state. We have generated a V408A mouse model of EA1, and find that it recapitulates the key aspects of the disease. Cerebellar Purkinje Cells (PCs) exhibit an intrinsically generated, tonic firing pattern that is modified by their inhibitory and excitatory inputs. Cerebellar Basket Cells (BCs) express Kv1.1 in their presynaptic terminals, and are the main source of inhibition to PCs. PCs in EA1 mice receive increased GABAergic transmission from BCs. I have found that this increase in GABAergic tone reduces the precision of the interspike interval of PC firing, which is critical for motor control. This PC firing precision deficit is a characteristic of other cerebellar ataxias. This difference is equalized by the GABAAR antagonist picrotoxin (PTX), indicating the importance of increased GABAergic tone in the disease model. For this reason, I propose to investigate the cellular mechanism by which V408A increases GABAergic transmission from BCs to PCs. I will use a combination of 2-photon Ca2+ imaging and electrophysiology to determine whether V408A increases action potential invasion throughout the large presynaptic terminals of BCs. I will assess the possibility that reduced Kv1.1 function increases probability of release for action potential-evoked events. I will additionally use paired-recordings of BC action potentials and PC IPSCs to determine percent failure of AP-induced GABA release. Accomplishing this aim will contribute to our understanding of the physiological role of K+ channels in the presynaptic control of neurotransmitter release, as well as its involvement in the pathophysiology of EA1. The proposed studies will engender novel insights into the cellular mechanisms responsible for a cerebellar ataxia, and may be applicable to additional ataxias.

描述（由申请人提供）：该提案的总体目标是确定电压门控钾通道亚基 Kv1.1 中的错义突变如何改变小脑输出并导致 1 型发作性共济失调 (EA1)。 V408A 是人类 EA1 突变之一，导致 Kv1.1 通道处于不稳定的开放状态。我们建立了 EA1 的 V408A 小鼠模型，并发现它概括了该疾病的关键方面。小脑浦肯野细胞 (PC) 表现出一种内在产生的强直放电模式，该模式通过其抑制性和兴奋性输入进行修改。小脑篮细胞 (BC) 在其突触前末梢表达 Kv1.1，是 PC 抑制的主要来源。 EA1 小鼠的 PC 接收来自 BC 的 GABA 能传输增加。 我发现 GABAergic 音调的增加降低了 PC 发射的峰间间隔的精度，这对于运动控制至关重要。这种 PC 发射精度缺陷是其他小脑共济失调的一个特征。这种差异被 GABAAR 拮抗剂印防己毒素 (PTX) 所平衡，表明增加 GABA 能张力在疾病模型中的重要性。 因此，我建议研究 V408A 增加从 BC 到 PC 的 GABA 能传输的细胞机制。我将结合使用 2 光子 Ca2+ 成像和电生理学来确定 V408A 是否会增加整个 BC 的大突触前末梢的动作电位侵袭。我将评估 Kv1.1 功能降低增加动作电位诱发事件释放概率的可能性。我还将使用 BC 动作电位和 PC IPSC 的配对记录来确定 AP 诱导的 GABA 释放的失败百分比。 实现这一目标将有助于我们了解 K+ 通道在突触前控制神经递质释放中的生理作用，以及它与 EA1 病理生理学的关系。 拟议的研究将对小脑共济失调的细胞机制产生新的见解，并且可能适用于其他共济失调。