Calcium channel and glutamate receptor signaling at synapses

突触处的钙通道和谷氨酸受体信号传导

• 批准号: 9000185
• 负责人: J. Julius Zhu
• 金额: $ 34.29万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-02-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9000185
• 关键词: Absence Epilepsy; Affect; Behavioral; Calcium; Calcium Channel; Cells; Chemosensitization; Coupled; Data; Drug usage; Electrons; Electrophysiology (science); Epilepsy; Ethosuximide; Excitatory Amino Acid Antagonists; Exhibits; Functional disorder; Genetic study; Glutamate Receptor; Glutamates; Human; Image; In Vitro; Intervention; Investigation; Lead; Light; Link; Mediating; Membrane; Membrane Potentials; Microscopic; Monitor; Mutation; N-Methylaspartate; Neurons; Neuropathy; Pathogenesis; Patients; Physiological; Physiology; Predisposition; Probability; Rattus; Receptor Signaling; Rest; Role; Secondary to; Seizures; Sleep; Synapses; Synaptic Transmission; Testing; gain of function; gain of function mutation; in vivo; mutant; public health relevance; research study; response; transmission process; two-photon; voltage

 DESCRIPTION (provided by applicant): T-type CaV3.2 calcium channels are widely expressed in various types of neurons and dysfunction of CaV3.2 channels has been strongly implicated in human childhood absence epilepsy (CAE). However, the role of these calcium channels in neurons remains unknown. More surprisingly, ~50% CAE patients did not respond to ethosuximide, a T-type Ca2+ channel antagonist and first-line drug used to treat CAE, and most of the nonresponsive patients carry gain-of-function Cav3.2 mutations. In this project, we plan to investigate the functional role of CaV3.2 channels in neuronal cells and the pathogenesis of ~20 CAE-linked human CaV3.2 channel mutations. In the preliminary investigation, we manipulated the activity of CaV3.2 channels genetically and pharmacologically, and monitored the effects with electrophysiological, two-photon imaging, electron microscopic and behavioral analyses. Our preliminary results consistently show that unlike other calcium channels, CaV3.2 channels function primarily to regulate NMDA-R-mediated transmission at synapses. Therefore, we hypothesize that CaV3.2 channels regulate synaptic NMDA transmission and that CAE- linked CaV3.2 channel mutations enhance susceptibility to absence seizures by potentiating glutamatergic transmission. Specifically, we will examine whether the activity of CaV3.2 channels enhances NMDA and AMPA responses in multiple different types of rat neurons in vitro and in vivo (Aim 1a). Moreover, we plan to study whether CaV3.2 channel activity-coupled synaptic calcium influx enhances NMDA responses that lead to the secondary potentiation of AMPA responses (Aim 1b). These results will define that the primary physiological function of neuronal CaV3.2 channels is to regulate glutamatergic synaptic transmission. In addition, we will examine how each of ~20 CAE- linked human CaV3.2 mutations may affect synaptic glutamatergic transmission (Aim 2a). Finally, we plan to investigate whether each of ~20 CAE-linked human CaV3.2 mutations may enhance the susceptibility to 2-4 Hz spike-and-wave discharges and absence-like seizures and if the seizures can be suppressed by glutamate receptor antagonists (Aim 2b). These results will shed new light on the mechanism and suggest new intervention for human CaV3.2 mutation-associated CAE.

 描述（由申请人提供）：T型CaV 3.2钙通道在各种类型的神经元中广泛表达，CaV 3.2通道的功能障碍与人类儿童失神癫痫（CAE）密切相关。然而，这些钙通道在神经元中的作用仍然未知。更令人惊讶的是，约50%的CAE患者对乙琥胺（一种T型Ca 2+通道拮抗剂和用于治疗CAE的一线药物）没有反应，并且大多数无反应的患者携带功能获得性Cav3.2突变。 在这个项目中，我们计划研究CaV3.2通道在神经元细胞中的功能作用以及约20种与CAE相关的人类CaV3.2通道突变的发病机制。在初步研究中，我们对CaV3.2通道的活性进行了基因调控，并通过电生理、双光子成像、电子显微镜和行为学分析等手段进行了监测。我们的初步结果一致表明，与其他钙通道，CaV3.2通道的功能主要是调节NMDA-R介导的突触传递。因此，我们假设CaV3.2通道调节突触NMDA传递，并且CAE连锁的CaV3.2通道突变通过增强突触能传递而增强对失神发作的易感性。具体而言，我们将研究CaV3.2通道的活性是否在体外和体内增强多种不同类型的大鼠神经元中的NMDA和AMPA反应（目的1a）。此外，我们计划研究CaV3.2通道活性偶联的突触钙内流是否增强NMDA反应，导致AMPA反应的次级增强（目的1b）。这些结果将确定神经元CaV3.2通道的主要生理功能是调节突触能传递。此外，我们将研究约20个CAE连锁的人CaV3.2突变中的每一个如何影响突触突触能传递（Aim 2a）。最后，我们计划研究约20种与CAE相关的人CaV3.2突变中的每一种是否可以增强对2-4 Hz棘波放电和失神样癫痫发作的易感性，以及癫痫发作是否可以被谷氨酸受体拮抗剂抑制（Aim 2b）。这些结果将揭示新的机制，并提出新的干预人类CaV3.2突变相关的CAE。