GABA activation of the M-current

M 电流的 GABA 激活

• 批准号: 10119723
• 负责人: Geoffrey W Abbott
• 金额: $ 38.15万
• 依托单位: UNIVERSITY OF CALIFORNIA-IRVINE
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-08-01 至 2021-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10119723
• 关键词: 3xTg-AD mouse; Affect; Alzheimer' s Disease; Alzheimer' s disease model; Alzheimer' s disease pathology; Amyloid beta-Protein Precursor; Behavioral; Binding Sites; Brain; Charge; Cognitive deficits; Complex; Data; Defect; Disease Progression; Down-Regulation; Drug Design; Ensure; Event; Family; Goals; Human; Impaired cognition; In Vitro; Influentials; Interneurons; Ion Channel; Ions; Kinetics; Learning; Link; Memory; Memory impairment; Molecular; Movement; Mus; Mutant Strains Mice; Neurons; Neurotransmitters; Parents; Pathogenesis; Pathogenicity; Pathologic; Physiology; Potassium; Potassium Channel; Process; Protein Precursors; Proteins; Proteolysis; Regulation; Resources; Role; Senile Plaques; Signal Transduction; Testing; Ursidae Family; amyloid formation; base; cognitive function; gamma-Aminobutyric Acid; in vivo; mouse model; mutant; neuronal circuitry; novel; novel therapeutics; prevent; receptor; success; voltage

This Alzheimer’s disease (AD) supplement proposal is based on two recent discoveries from the Abbott lab. The first discovery, which forms the basis of the parent R01, is that KCNQ2/3 voltage-gated potassium (Kv) channels are directly activated by γ-aminobutyric acid (GABA), the primary inhibitory neurotransmitter in vertebrate CNS, with a sensitivity comparable to that of the most sensitive canonical GABAA receptors. This newly described form of regulation is potentially highly influential because KCNQ2/3 channels are the primary molecular correlate of neuronal M-current, a powerful inhibitory force in mammalian brain. The second discovery is our more recent finding that the Alzheimer’s precursor protein (APP) cleavage product, C99, both bears similarities to the KCNE family of Kv channel regulatory subunits, and itself regulates multiple Kv channels, including those of the KCNQ family. Specifically, we found that C99 co-localizes with KCNQ2/3 in vivo, forms physical complexes with KCNQ2/3 in vitro, and inhibits KCNQ2/3 function in vitro. We now intend to study the relevance to AD of C99 regulation of KCNQ2/3 channels in vivo, as a logical extension of the parent R01, bringing an AD perspective to it. We propose two Specific Aims directed towards a fuller understanding of the novel potential role in AD pathology of C99, APP and potentially other APP cleavage product inhibition of neuronal KCNQ channels. We plan to utilize the Kcnq3 and Kcnq5 GABA binding-site mutant mouse lines we developed for the parent R01, in conjunction with the well-characterized 3xTg-AD mouse model that mimics many features of human AD. In Aim 1, we will test the hypothesis that neuronal M-current is inhibited in the 3xTg-AD mouse brain. This hypothesis is based on our in vitro data, that suggest increased neuronal concentrations of C99, and potentially other APP cleavage products, will inhibit neuronal M-current and alter its gating kinetics in vivo. We will also determine whether 3xTg-AD mouse brains have altered GABA regulation of M-current, linking this aim tightly with the parent R01 but with an AD focus that was absent from the parent R01. In Aim 2, we will test the hypothesis that disrupted GABA regulation of M-current exacerbates behavioral changes in AD. We will quantify behavioral changes in Kcnq3-W265L and Kcnq5-W270L GABA binding-site mutant mice bred for the parent R01, in both a wild-type and 3xTg-AD background, and compare them to homozygous 3xTg-AD mice, to determine if disruption of GABA modulation of KCNQ channels exacerbates AD pathogenesis. The overall goals of this AD supplement are to (i) determine if C99 accumulation in early AD correlates with downregulation of M-current, as suggested by our in vitro studies and (ii) determine how this affects neuronal firing; (iii) identify whether preventing GABA modulation of KCNQ channels exacerbates neuronal and M-current firing defects, and behavioral abnormalities, in AD. The studies in this supplement have the potential to identify novel therapeutic directions for cognitive dysfunction in AD.

这项阿尔茨海默病 (AD) 补充剂提案基于雅培实验室最近的两项发现。 第一个发现是 KCNQ2/3 电压门控钾 (Kv)，它构成了母体 R01 的基础 通道由γ-氨基丁酸（GABA）直接激活，γ-氨基丁酸是体内主要的抑制性神经递质 脊椎动物中枢神经系统，其敏感性与最敏感的经典 GABAA 受体相当。 新描述的监管形式可能具有很大的影响力，因为 KCNQ2/3 通道是主要的 神经 M 电流的分子相关性，哺乳动物大脑中的强大抑制力。 我们最近的发现是阿尔茨海默病前体蛋白 (APP) 裂解产物 C99 与 Kv 通道调节亚基的 KCNE 家族有相似之处，其本身调节多个 Kv 具体而言，我们发现 C99 与 KCNQ2/3 共定位。 在体内，与 KCNQ2/3 形成物理复合物，并在体外抑制 KCNQ2/3 功能。 研究 C99 体内 KCNQ2/3 通道调节与 AD 的相关性，作为亲本的逻辑延伸 R01，引入 AD 视角，旨在更全面地理解它。 C99、APP 和潜在的其他 APP 裂解产物抑制在 AD 病理学中的新潜在作用 我们计划利用 Kcnq3 和 Kcnq5 GABA 结合位点突变小鼠品系。 为母体 R01 开发，与特征良好的 3xTg-AD 小鼠模型相结合，该模型模仿 在目标 1 中，我们将检验神经 M 电流在 AD 中受到抑制的假设。 3xTg-AD 小鼠大脑这一假设基于我们的体外数据，表明神经元增加。 C99 和潜在的其他 APP 裂解产物的浓度将抑制神经元 M 电流并改变其 我们还将确定 3xTg-AD 小鼠大脑是否改变了 GABA 调节。 M-当前，将这一目标与父代 R01 紧密联系在一起，但父代中没有 AD 焦点 R01。在目标 2 中，我们将检验 M 电流 GABA 调节受到破坏会导致行为恶化的假设。 我们将量化 Kcnq3-W265L 和 Kcnq5-W270L GABA 结合位点的行为变化。 在野生型和 3xTg-AD 背景下为亲本 R01 培育的突变小鼠，并将它们与 纯合 3xTg-AD 小鼠，以确定 KCNQ 通道 GABA 调节的破坏是否会恶化 AD 该 AD 补充剂的总体目标是 (i) 确定 C99 是否在早期 AD 中积累。 正如我们的体外研究所表明的，与 M 电流的下调相关，并且 (ii) 确定这如何 影响神经放电；（iii）确定是否阻止 KCNQ 通道的 GABA 调节恶化 AD 中的神经元和 M 电流放电缺陷以及行为异常。 有潜力确定 AD 认知功能障碍的新治疗方向。