Understanding the Mechanism and Preventing the Unique Neuropathology of Arginase Deficiency

了解精氨酸酶缺乏的机制并预防独特的神经病理学

• 批准号: 10540721
• 负责人: Gerald S Lipshutz
• 金额: $ 34.13万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-04-15 至 2024-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10540721
• 关键词: Acids; Acute; Address; Adoption; Anatomy; Animals; Arginine; Birth; Brain; Bystander Effect; Cells; Central Nervous System; Cerebral cortex; Cessation of life; Chronic; Classification; Clinical; Clinical Trials; Congenital neurologic anomalies; Creatine; Data; Disease; Electrophysiology (science); Enzymes; Etiology; Exposure to; Failure to Thrive; Functional disorder; Gene Expression; Goals; Growth; Health; Hepatic; Hyperammonemia; Hyperargininemia; Impairment; Inborn Errors of Metabolism; Inequality; Interneurons; Intervention; Knock-out; Knockout Mice; Laboratories; Life; Liver; Measurable; Measures; Mediating; Metabolism; Microcephaly; Motor Cortex; Mus; Myelin; Neonatal; Nervous System Trauma; Neurologic; Neuronal Dysfunction; Neuronal Injury; Neurons; Oligodendroglia; Pathogenesis; Patients; Periodicals; Peripheral; Plasma; Play; Psyche structure; Recombinant adeno-associated virus (rAAV); Research; Resolution; Role; Seizures; Slice; Synapses; Synaptic Transmission; Taurine; Testing; Toxin; Urea cycle disorders; arginase; central nervous system injury; density; dysmyelination; excitatory neuron; experimental study; gene therapy; improved; infancy; knockout animal; leukodystrophy; mouse model; myelination; nervous system disorder; neuropathology; novel therapeutics; patch clamp; pharmacologic; postnatal; prevent; response; restoration; spasticity; transmission process; urea cycle

Project Summary/Abstract The overall goals of this project are to 1) investigate the etiology of the unique neuropathology associated with arginase 1 (A1) deficiency, a disorder of the urea cycle, and 2) to extensively demonstrate that AAV-based hepatic gene therapy is effective in preventing the features of this disorder as a prelude to a clinical trial. A1 deficiency results in chronic hyperargininemia characterized by progressive mental impairment, spasticity, and growth retardation, with only periodic episodes of hyperammonemia. Recent and preliminary findings from our laboratory with the A1-deficient mouse have demonstrated substantial anatomical, ultrastructural and electro- physiological differences between knockouts and wild types. A1 deficiency led to decreased intrinsic excita- bility, altered functional synaptic transmission, decreased dendritic arborization, dysmyelination and decreased synaptic density. The most likely mechanism causing these neuronal abnormalities is hyperarginine- or guani- dino compound-mediated dysfunction of neurons and oligodendrocytes. Controlling plasma arginine and guani- dino compounds following administration of liver-specific AAV-based gene therapy resulted in much of these measures being substantially improved. The finding abnormalities at the neuron, synapse, myelin, and circuit level have begun to elucidate the functional deficits in A1 deficiency. The identification of the proximate toxin and mechanism of neurodysfunction will open doors to potential pharmacological interventions for A1 deficiency in addition to gene therapy, and may open avenues to new therapies for other disorders where dysmyelination is a feature. Preliminary data: Our research group has (amongst other findings): 1) constructed and characterized the A1-deficient mouse; 2) demonstrated long-term survival with liver-specific recombinant AAV; 3) demonstrated that only low-level ureagenesis is necessary for survival; 4) shown that gene therapy- treated A1 knockout mice lack gross nervous system abnormalities; 5) shown that peripheral metabolism results in control of circulating plasma arginine; and 6) shown that loss of A1 gene expression results in abnormalities of intrinsic excitability, synapse type and number, myelination and the dendritic arbor of neurons. In Aim 1, the hypothesis that oligodendrocyte dysfunction and death result in dysmyelination and is in part the cause of neuronal dysfunction in A1 deficiency will be tested. In Aim 2, the hypothesis that elevated guanidino compounds can induce alterations in intrinsic excitability and synaptic transmission that are similar to those seen in A1 deficient animals will be tested. In Aim 3, it will be determined if A1 deficiency causes an imbalance in excitation and inhibition, and if this inequality is mainly through effects on perisomatic inhibition. Completion of these studies will provide a greater understanding of and the mechanism(s) behind the alterations in the brain, neurons, and synapses in A1 deficiency and hyperargininemia while demonstrating the efficacy of hepatic A1 gene therapy in preventing these abnormalities, providing strong evidence for this therapy as a prelude to its clinical adoption in patients with this progressive neurological disorder.

项目摘要/摘要 该项目的总体目标是1）研究与 精氨酸酶1（A1）缺陷，尿素周期的疾病，2）广泛证明基于AAV的 肝基因疗法可有效防止这种疾病的特征作为临床试验的前奏。 A1 缺乏会导致慢性高氨基血症，其特征是进行性心理障碍，痉挛和 生长迟钝，仅周期性发作高症。我们的最新和初步发现 具有A1缺陷小鼠的实验室表现出大量的解剖学，超微结构和电型 淘汰赛和野生类型之间的生理差异。 A1缺乏导致固有的兴奋性降低 能力，功能性突触传播改变，树突状木器化降低，炎症和降低 突触密度。引起这些神经元异常的最可能机制是超甲胺或鸟嘌呤 恐龙化合物介导的神经元和少突胶质细胞功能障碍。控制血浆精氨酸和鸟嘌呤 施用肝特异性AAV基因疗法后的恐龙化合物导致了许多 措施大大改善。神经元，突触，髓磷脂和电路的发现异常 水平已经开始阐明A1缺陷中的功能缺陷。接近毒素的鉴定 神经发育功能的机制将为A1的潜在药理干预打开大门 除基因疗法外，不足，并且可能为其他疾病的新疗法开放 功能障碍是一个功能。初步数据：我们的研究小组（除其他发现）：1）构建 并表征了A1缺陷鼠标； 2）证明了具有肝特异性重组的长期生存 aav; 3）证明只有低水平的尿素发生才能生存； 4）表明基因治疗 - 治疗的A1敲除小鼠缺乏神经系统的严重异常。 5）表明外周代谢 导致控制循环血浆精氨酸； 6）表明A1基因表达的丧失导致 内在兴奋性，突触类型和数量，髓鞘形成和神经元的树突状乔木的异常。 在AIM 1中，少突胶质细胞功能障碍和死亡的假说导致障碍性，部分是 将测试A1缺乏症中神经元功能障碍的原因。在AIM 2中，提升圭尼迪诺的假设 化合物可以诱导内在兴奋性和突触传播的改变，这与那些相似 将测试在A1缺乏的动物中。在AIM 3中，将确定A1缺陷是否导致失衡 在激发和抑制作用中，如果这种不平等主要是通过对围par抑制的影响。完成 这些研究将提供对改变的改变背后的更多理解和机制 大脑，神经元和突触在A1缺乏症和高氨基血症中血症，同时证明了 肝A1基因疗法在预防这些异常方面，为这种疗法提供了有力的证据 在这种进行性神经系统疾病的患者中采用临床采用的前奏。