Mechanisms of Seizure Resistance in a Mouse Genetic Model with Altered Metabolism

代谢改变的小鼠遗传模型中的癫痫发作抵抗机制

• 批准号: 10733666
• 负责人: GARY I YELLEN
• 金额: $ 42.38万
• 依托单位: HARVARD MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-03-01 至 2027-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10733666
• 关键词: ATP sensitive potassium channel complex; Acute; Affect; Animals; Anticonvulsants; Antioxidants; Apoptosis Regulation Gene; Apoptotic; Bad protein; Biosensor; Brain; Carbohydrates; Carbon; Caregivers; Cells; Cellular Metabolic Process; Chronic; Convulsants; Data; Diet; Diet therapy; Disease; Effectiveness; Energy Metabolism; Epilepsy; Equilibrium; Event; Exhibits; Gene Mutation; Genes; Genetic; Genetic Models; Glucose; Glycolysis; Goals; Grant; Intervention; Intractable Epilepsy; Ion Channel; Ketone Bodies; Knock-out; Label; Metabolic; Metabolism; Modeling; Molecular; Monitor; Mus; Mutation; NADP; Neurons; Oxidation-Reduction; Oxygen; Pentosephosphate Pathway; Persons; Point Mutation; Potassium Channel; Predisposition; Probability; Production; Resistance; Reverse engineering; Role; Seizures; Signal Transduction; Slice; Source; Status Epilepticus; Testing; Therapeutic; Work; brain cell; brain metabolism; dietary; effective therapy; enzyme activity; experience; in vivo; inhibitor; ketogenic diet; mouse genetics; mouse model; neuronal excitability; novel therapeutic intervention; novel therapeutics; pharmacologic; prevent; public health relevance; response; tool

PROJECT SUMMARY / ABSTRACT Drug-resistant epilepsy is seriously debilitating and very common, affecting about one-third of the 1-2% of people who experience epilepsy during their lifetime. One of the most effective treatments for drug-resistant epilepsy is dietary therapy, in the form of a very-low-carbohydrate, ketogenic diet. Despite its effectiveness, this diet is not very widely used because of the stringency of the diet and the high commitment required of clinicians and other caregivers. It would be very valuable to understand the mechanism by which altered metabolism produces resistance to epileptic seizures, to “reverse-engineer” it, and to discover alternative pharmacologic ways of tapping into this potent and apparently unique anti-seizure mechanism. We have identified a mouse model that recapitulates the seizure resistance seen in ketogenic diet, but that involves a mutation in a single gene, Bad. The seizure resistance in this genetic model is due to alteration in brain cell metabolism, with less glucose utilization and better utilization of alternative fuels such as ketone bodies, similar to the metabolic changes on a ketogenic diet. We have also discovered a downstream mechanism that is altered both by Bad alteration and by ketogenic diet: a metabolically sensitive class of ion channels, the ATP- sensitive potassium channels (KATP channels), become more activated in response to metabolic changes. These channels are critical for seizure resistance of the Bad-altered mice, and we have also found that they are responsible for anti-seizure effects of BAD knockout in a brain slice model of seizure. Recent findings reveal that BAD knockout produces specific changes in core carbon metabolism – specifically in the pentose phosphate pathway (PPP) – and that direct manipulation of the PPP can recapitulate the cellular changes in KATP channel activity that underlie the metabolic seizure resistance in BAD knockout. We propose to test two complementary hypotheses of how altered PPP activity can signal to KATP channels, and distinguishing these hypotheses is important because they make opposite predictions for how antioxidants, alternative neuronal fuels, and oxidative signaling may alter the antiseizure effects both in BAD knockout and in dietary treatment. One hypothesis focuses on the reduced ability in BAD knockout for the neuronal PPP to produce NADPH, which is central to cellular antioxidant function; this could make native reactive oxygen signaling more effective. The second hypothesis is that it is not the reduced ability to produce the NADPH byproduct, but rather the reduced substrate flux through the PPP that alters downstream energy metabolism. We will also expand our in vivo studies, testing the ability of BAD and PPP manipulation to affect seizures in a chronic mouse model of epilepsy, Together these studies will reveal the mechanistic basis of metabolic seizure resistance, and will point toward new therapeutic avenues for drug-resistant epilepsy.

项目概要/摘要 耐药性癫痫会严重使人衰弱，而且很常见，影响 1-2% 人群中的约三分之一 在一生中经历过癫痫的人。耐药性癫痫最有效的治疗方法之一是 饮食疗法，采用极低碳水化合物、生酮饮食的形式。尽管这种饮食方法有效，但它并不 由于饮食的严格性以及临床医生和其他人员的高度承诺要求，因此被广泛使用 照顾者。了解改变新陈代谢产生的机制将非常有价值 对癫痫发作的抵抗力，对其进行“逆向工程”，并发现替代的药理学方法 利用这种有效且明显独特的抗癫痫机制。 我们已经确定了一种小鼠模型，可以概括生酮饮食中观察到的癫痫发作抵抗力，但是 涉及单个基因的突变，Bad。该遗传模型中的癫痫发作抵抗力是由于 脑细胞新陈代谢，减少葡萄糖的利用，更好地利用酮体等替代燃料， 类似于生酮饮食的代谢变化。我们还发现了一个下游机制 因不良改变和生酮饮食而改变：一类代谢敏感的离子通道，ATP- 敏感的钾通道（KATP 通道）因代谢变化而变得更加活跃。这些 这些通道对于 Bad 突变小鼠的癫痫抵抗能力至关重要，我们还发现它们 负责癫痫脑切片模型中 BAD 敲除的抗癫痫作用。 最近的研究结果表明，BAD 敲除会导致核心碳代谢发生特定变化 - 特别是 磷酸戊糖途径 (PPP) – 直接操纵 PPP 可以概括细胞 KATP 通道活性的变化是 BAD 敲除中代谢性癫痫抵抗的基础。我们建议 测试两个互补的假设，即改变的 PPP 活性如何向 KATP 通道发出信号，并区分 这些假设很重要，因为它们对抗氧化剂、替代神经元如何发挥作用做出了相反的预测 燃料和氧化信号可能会改变 BAD 敲除和饮食治疗中的抗癫痫作用。 一种假设集中于 BAD 敲除后神经元 PPP 产生 NADPH 的能力降低，这 是细胞抗氧化功能的核心；这可以使天然活性氧信号传导更加有效。这 第二个假设是，这并不是产生 NADPH 副产物的能力降低，而是产生 NADPH 副产物的能力降低。 通过 PPP 的底物通量改变下游能量代谢。我们还将扩大我们的体内 研究，测试 BAD 和 PPP 操作影响慢性癫痫小鼠模型癫痫发作的能力， 这些研究将共同​​揭示代谢性癫痫抵抗的机制基础，并将指向 耐药性癫痫的新治疗途径。