The mitochondrial Ca2+ uniporter in the regulation of neural activity and susceptibility to seizures

项目概要/摘要 癫痫是一种常见的神经系统疾病，影响大约7000万人。对于许多患者来说， 癫痫可以通过药物治疗来控制;然而，大约30%的患者 难治性癫痫，目前的药物干预无法控制。难治性癫痫是 与癫痫猝死（SUDEP）的高风险相关，这是癫痫的主要原因。 在这个病人群体中。此外，不受控制的癫痫和频繁发作与 进行性认知能力下降，以及显著的行为和精神共病。因此， 这对于确定难治性癫痫患者的新的关键治疗靶点至关重要。主要 本研究的目的是确定线粒体Ca 2+单向转运体（MCU）在调节突触的作用， 功能、神经网络活动和癫痫易感性。MCU是线粒体Ca 2+的核心成分 它是钙摄取复合物的一部分，参与钙信号传导、生物能量学和细胞死亡的调节。我们专注于 MCU的灵感来自于我们在试点研究中所做的几项新观察。首先，我们发现MCU 敲除（KO）在体内和体外均产生强的抗惊厥作用。第二，具体删除MCU GABA能神经元足以产生抗惊厥作用，而谷氨酸能神经元则不然。三、MCU 缺失增强GABA能突触传递，但不改变GABA能传递或内源性 神经元兴奋性第四，MCU缺失保护神经元免受谷氨酸诱导的Ca 2+失调， 毒性后者是重要的，因为兴奋性毒性有助于显着的癫痫神经元损伤。 总的来说，这些数据表明，抑制MCU将在癫痫的背景下提供双重益处，首先， 通过增加癫痫发作阈值，第二，通过保护神经元免受与癫痫发作相关的兴奋性毒性。 我们推测，MCU在调节GABA能突触传递和神经元突触传递中起重要作用。 活性，并且MCU缺失通过增强GABA能突触传递产生抗惊厥作用 并防止神经网络过度兴奋。我们还假设MCU删除提供了保护， 与癫痫有关的神经毒性这些中心假设将在3个具体目标中进行检验。要求1 将确定GABA能和谷氨酸能神经元在MCU缺失的抗惊厥作用中的作用。 目的2将确定MCU在抑制性和兴奋性中枢突触中的作用。目标3将决定作用 MCU在癫痫诱导的神经元毒性中的作用。拟议的研究将提供一个机制的见解， 线粒体钙转运在调节突触网络活动中的作用， 对过度兴奋和癫痫发作的敏感性，并可能导致新的策略的发展， 线粒体Ca 2+转运和MCU用于治疗癫痫以及其他神经系统疾病 与异常神经活动有关

Project Summary/Abstract Epilepsy is a common neurological disorder that affects approximately 70 mln people. For many patients, epilepsy can be controlled through pharmaceutical therapies; however, approximately 30% of patients develop refractory epilepsy that cannot be controlled with current pharmaceutical interventions. Refractory epilepsy is associated with a high risk for sudden unexpected death in epilepsy (SUDEP), which is the leading cause of death in this patient population. In addition, uncontrolled epilepsy and frequent seizures are associated with progressive cognitive decline, as well as significant behavioral and psychiatric comorbidities. Thus, it is of paramount importance to identify novel critical therapeutic targets for patients with refractory epilepsy. The main objective of this proposal is to establish the role of the mitochondrial Ca2+ uniporter (MCU) in regulating synaptic function, neural network activity and seizure susceptibility. MCU is the core component of the mitochondrial Ca2+ uptake complex and is involved in the regulation of Ca2+ signaling, bioenergetics and cell death. Our focus on MCU is inspired by several novel observations we made during our pilot studies. First, we found that MCU knockout (KO) produces robust anticonvulsant effects both in vivo and in vitro. Second, deleting MCU specifically in GABAergic, but not in glutamatergic, neurons was sufficient to produce an anticonvulsant effect. Third, MCU deletion enhanced GABAergic synaptic transmission, but did not alter glutamatergic transmission or intrinsic neuronal excitability. Fourth, MCU deletion protected neurons from glutamate-induced Ca2+ deregulation and toxicity. The latter is important because excitotoxicity contributes significantly to neuronal damage in epilepsy. Collectively, these data suggest that inhibiting MCU would provide a dual benefit in the context of epilepsy, first by increasing seizure threshold, and second, by protecting neurons from excitotoxicity associated with seizures. We hypothesize that MCU plays an important role in regulating GABAergic synaptic transmission and neural activity, and that MCU deletion produces anticonvulsant effects by enhancing GABAergic synaptic transmission and preventing neural network hyperexcitability. We also hypothesize that MCU deletion provides protection from neurotoxicity associated with seizures. These central hypotheses will be tested in 3 specific aims. Aim 1 will establish the roles of GABAergic and glutamatergic neurons in the anticonvulsant effect of MCU deletion. Aim 2 will determine the role of MCU at inhibitory and excitatory central synapses. Aim 3 will determine the role of MCU in epilepsy-induced neuronal toxicity. The proposed studies will provide mechanistic insight into a previously unrecognized role of mitochondrial Ca2+ transport in regulating the activities of synaptic networks and susceptibility to hyperexcitability and seizures, and could lead to development of new strategies targeting mitochondrial Ca2+ transport and MCU for the treatment of epilepsy as well as other neurological disorders associated with aberrant neural activity.