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

项目摘要/摘要 癫痫是一种常见的神经疾病，大约有7000万人受到影响。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%的患者会发展成 难治性癫痫，不能用目前的药物干预措施控制。难治性癫痫是 与癫痫突发意外死亡(SUDEP)的高风险相关，这是导致 在这个病人群体中死亡。此外，失控的癫痫和频繁的癫痫发作与 进行性认知衰退，以及严重的行为和精神共病。因此，它是 为难治性癫痫患者确定新的关键治疗靶点至关重要。主 本研究的目的是确定线粒体钙离子单一转运体(MCU)在调节突触中的作用 功能、神经网络活动和癫痫敏感性。MCU是线粒体钙离子的核心成分 摄取复合体，参与钙信号、生物能量学和细胞死亡的调节。我们的重点是 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 基因敲除(KO)在体内和体外都有很强的抗惊厥作用。第二，具体删除MCU 在GABA能神经元中，而在谷氨酸能神经元中，神经元足以产生抗惊厥作用。第三，MCU 缺失增强了GABA能突触传递，但不改变谷氨酸能传递或固有的 神经元兴奋性。第四，MCU缺失保护神经元免受谷氨酸诱导的钙离子释放和 毒性。后者很重要，因为兴奋性毒性在癫痫中对神经元的损伤起着重要作用。 总而言之，这些数据表明，首先，在癫痫的背景下，抑制MCU将提供双重好处 通过提高癫痫发作阈值，第二，通过保护神经元免受癫痫发作相关的兴奋性毒性。 我们推测MCU在调节GABA能突触传递和神经过程中起重要作用 MCU缺失通过增强GABA能突触传递而产生抗惊厥作用 并防止神经网络过度兴奋。我们还假设MCU删除提供了保护 与癫痫发作相关的神经毒性。这些核心假设将在三个具体目标上得到检验。目标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确定MCU在抑制性和兴奋性中枢性突触中的作用。目标3将决定角色 MCU在癫痫诱导的神经元毒性中的作用。拟议的研究将提供对 线粒体钙转运在调节突触网络活动中的作用 对过度兴奋和癫痫的易感性，并可能导致开发新的靶向策略 线粒体Ca~(2+)转运和MCU治疗癫痫等神经系统疾病 与异常的神经活动有关。

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.