Arginase and Regulation of Nitric Oxide Synthase in ALS

ALS 中精氨酸酶和一氧化氮合酶的调节

基本信息

批准号：
6661173
负责人：
RAJIV R RATAN
金额：
$ 33.22万
依托单位：
BETH ISRAEL DEACONESS MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2001
资助国家：
美国
起止时间：
2001-08-15 至 2005-07-31
项目状态：
已结题

项目摘要

DESCRIPTION (Adapted from applicant's abstract): Amyotrophic lateral sclerosis is a prevalent neurological disorder characterized by inexorable muscle weakness leading to death. The principal pathological finding in amyotrophic lateral sclerosis is loss of nerve cells in the anterior horns of the spinal cord, the motor nuclei of the brainstem, and the upper motor neurons of the cerebral cortex. Investigations aimed at preventing or limiting progression of amyotrophic lateral sclerosis have thus focused on the mechanisms by which neurons degenerate. A transgenic mouse model has been developed that possesses many of the pathological and clinical features of human familial and sporadic amyotrophic lateral sclerosis. As nitric oxide (NO) has been shown to mediate neuronal loss in other neurodegenerative conditions, several groups have investigated the role that NO may play in disease progression | in the transgenic model. The results have been conflicting likely because currently available inhibitors of nitric oxide synthase do not permit optimal control of NO generation within particular cell types and subcellular compartments. A novel potential strategy for regulating nitric oxide synthesis involves the enzyme arginase that can | regulate availability of arginine in the cytoplasm or mitochondria. In preliminary studies, we have shown that: 1) extracellular arginase blocks neuronal apoptosis and 2) arginase immunoreactivity is, upregulated in the spinal cord of ALS transgenic mice as well as humans with the sporadic and familial forms of amyotrophic lateral sclerosis. These preliminary results lead to the overall hypothesis to be tested in this proposal: about Interventions aimed at promoting arginase activities in microglia, astrocytes and/or motor neurons will limit availability of cell arginine for toxic NO generation and thereby diminish cell death and disease progression in amyotrophic lateral sclerosis but permit NO to, mediate its survival promoting effects in each of these cell types. We propose to test this hypothesis by: 1) determining the cell types and subcellular compartments where arginase is expressed in the normal central nervous system of humans and mice, and how the localization and levels of these isoforms change in amyotrophic lateral sclerosis as well as in a transgenic mouse! Model of amyotrophic lateral sclerosis and how this compares to the localization of NOS (all forms) in these tissues; and 2) determining whether increased arginase activity in microglia, astrocytes or neurons from control mice or mice over expressing SOD1 mutant (G93A) will abrogate NO mediated toxicity of motor neurons induced by growth factor deprivation, excitotoxins or LPS/IFN-gamma treatment. These studies promise to enhance our understanding of how arginine about metabolism, including the synthesis of NO, is regulated in the normal and abnormal nervous system.

描述（改编自申请人的摘要）：肌萎缩侧索硬化症是一种普遍的神经系统疾病，其特征是肌肉不可抗拒虚弱导致死亡。肌萎缩侧索硬化症的主要病理学发现侧索硬化症是脊柱前角神经细胞的损失脊髓、脑干运动核和上运动神经元大脑皮层。旨在预防或限制病情进展的研究因此，肌萎缩侧索硬化症的发病机制已成为人们关注的焦点。神经元退化。已经开发出一种转基因小鼠模型，该模型具有人类家族性和散发性的许多病理和临床特征肌萎缩侧索硬化症。由于一氧化氮 (NO) 已被证明可以介导其他神经退行性疾病中的神经元损失，一些研究小组发现研究了一氧化氮在疾病进展中可能发挥的作用在转基因模型。结果可能是相互矛盾的，因为目前现有的一氧化氮合酶抑制剂不允许最佳控制特定细胞类型和亚细胞区室中产生 NO。一个调节一氧化氮合成的新的潜在策略涉及精氨酸酶可以|调节细胞质中精氨酸的可用性或线粒体。在初步研究中，我们已经表明：1）细胞外精氨酸酶阻断神经元凋亡，2) 精氨酸酶免疫反应性是， ALS 转基因小鼠以及患有 ALS 的人类的脊髓中表达上调散发性和家族性形式的肌萎缩侧索硬化症。这些初步结果导致了本次测试的总体假设提案：关于旨在促进精氨酸酶活动的干预措施小胶质细胞、星形胶质细胞和/或运动神经元将限制细胞的可用性精氨酸产生有毒的一氧化氮，从而减少细胞死亡和疾病肌萎缩侧索硬化症的进展，但允许 NO 介导其对这些细胞类型中的每一种都有促进生存的作用。我们建议对此进行测试假设通过：1）确定细胞类型和亚细胞区室，其中精氨酸酶在人类和小鼠的正常中枢神经系统中表达，以及这些亚型的定位和水平在肌萎缩侧索硬化症中如何变化侧索硬化症以及转基因小鼠！肌萎缩模型侧索硬化症及其与 NOS 定位（所有形式）的比较在这些组织中； 2) 确定精氨酸酶活性是否增加来自对照小鼠或过度表达 SOD1 的小鼠的小胶质细胞、星形胶质细胞或神经元突变体（G93A）将消除 NO 介导的运动神经元毒性生长因子剥夺、兴奋毒素或 LPS/IFN-γ 治疗。这些研究有望增强我们对精氨酸如何影响新陈代谢的理解，包括 NO 的合成，在正常和异常神经中受到调节系统。