NAD metabolism and mitochondrial dysfunction in ALS models

ALS 模型中的 NAD 代谢和线粒体功能障碍

• 批准号: 10084091
• 负责人: Marcelo R Vargas
• 金额: $ 18.92万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-01 至 2020-09-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10084091
• 关键词: NAD; metabolism; mitochondrial; dysfunction; ALS

 DESCRIPTION (provided by applicant): The long-term goal of the proposal is to develop new therapeutic strategies using mechanistic insights drawn from understanding astrocyte-motor neuron interaction in amyotrophic lateral sclerosis (ALS). In particular, the primary objective of this proposal is to establish whether increased nicotinamide adenine dinucleotide (NAD) availability ameliorates motor neuron degeneration in ALS models. ALS or Lou Gehrig's disease accounts for about 1 in 500 to 1 in 1,000 adult deaths in the United States and is caused by the progressive degeneration of motor neurons in the spinal cord, brain stem, and motor cortex. Motor neuron death leads to muscle weakness and paralysis causing death in one to five years from the time of symptoms onset. Most ALS cases are sporadic (SALS) and exposure to yet unidentified environmental toxicants might be responsible for SALS. About 5-10% of the cases are inherited (familial ALS, FALS) but FALS and SALS are phenotypically indistinguishable, and a significant share of our understanding come from the study of rodent models over-expressing ALS-linked mutant human superoxide dismutase 1 (hSOD1). Primary astrocytes isolated from mutant hSOD1 over-expressing mice induce motor neuron death in co-culture, and it has been demonstrated that astrocytes differentiated from spinal cord autopsy-derived neuronal progenitor cells from FALS and SALS patients are also toxic for motor neurons in co-culture. Sirtuins are a family of enzymes capable of catalyzing NAD-dependent deacylation and mono(ADPribosyl)ation reactions. Remarkably, NAD- dependent sirtuin-mediated deacetylation has been shown to modulate all major mitochondrial processes. Since mitochondrial dysfunction has been linked to ALS and the toxicity of ALS-astrocytes, we seek to better define the role of NAD-dependent signaling in motor neuron degeneration and determine if the modulation of NAD levels may be a potential therapeutic strategy for ALS. Our ongoing experiments demonstrate that increasing NAD content in ALS-astrocytes reverts its toxicity towards co-cultured motor neurons, while NAD synthesis and NAD-dependent signaling may be compromised in mutant hSOD1 mice. Thus, the specific aims of the proposal are: Aim 1-To determine the role of NAD content in the toxicity of astrocytes expressing ALS- linked mutant hSOD1s toward co-cultured motor neurons. Aim 2-To evaluate the effect of transgenic models with altered NAD synthesis and degradation on the onset and progression of the disease in ALS mouse models. Aim 3-To evaluate the effect of treatment with a key NAD precursor on the onset and progression of the disease in ALS mouse models. The outcome of the proposal will contribute to the current understanding of NAD metabolism and mitochondrial dysfunction in neurodegeneration. More important, since we have shown that therapeutic targets identified in our astrocyte-motor neuron co-culture system have a beneficial effect when translated into animal models of ALS, the proposal is likely to provide in vivo proof of the value of modulating NAD metabolism as a therapeutic target in ALS.

 描述（由申请人提供）：该提案的长期目标是利用从了解肌萎缩侧索硬化症（ALS）中星形胶质细胞-运动神经元相互作用中得出的机制见解开发新的治疗策略。具体而言，该提议的主要目的是确定增加的烟酰胺腺嘌呤二核苷酸（NAD）可用性是否改善ALS模型中的运动神经元变性。ALS或Lou Gehrig病在美国约占500至1，000成人死亡人数中的1人，并且由脊髓，脑干和运动皮层中的运动神经元的进行性变性引起。运动神经元死亡导致肌肉无力和瘫痪，导致症状发作后1至5年内死亡。大多数ALS病例是散发性的（SALS），暴露于尚未鉴定的环境毒物可能是导致SALS的原因。大约5-10%的病例是遗传性的（家族性ALS，FALS），但FALS和SALS在表型上是无法区分的，我们的理解很大一部分来自对过表达ALS连锁突变体人超氧化物歧化酶1（hSOD 1）的啮齿动物模型的研究。从突变型hSOD 1过表达小鼠中分离的原代星形胶质细胞在共培养中诱导运动神经元死亡，并且已经证明，从来自FALS和SALS患者的脊髓尸检衍生的神经元祖细胞分化的星形胶质细胞在共培养中也对运动神经元有毒。沉默调节蛋白是能够催化NAD依赖性脱酰和单（ADP核糖基）化反应的酶家族。值得注意的是，NAD依赖性沉默调节蛋白介导的脱乙酰化已显示调节所有主要的线粒体过程。由于线粒体功能障碍与ALS和ALS-星形胶质细胞的毒性有关，我们试图更好地定义NAD依赖性信号传导在运动神经元变性中的作用，并确定NAD水平的调节是否可能是ALS的潜在治疗策略。我们正在进行的实验表明，增加NAD含量ALS-星形胶质细胞恢复其对共培养的运动神经元的毒性，而NAD合成和NAD依赖性信号可能会在突变hSOD 1小鼠受损。因此，该提案的具体目的是：目的1-确定NAD含量在表达ALS连锁突变体hSOD 1的星形胶质细胞对共培养的运动神经元的毒性中的作用。目的2-评估具有改变的NAD合成和降解的转基因模型对ALS小鼠模型中疾病的发作和进展的影响。目的3-评估用关键NAD前体治疗对ALS小鼠模型中疾病的发作和进展的影响。该提案的结果将有助于目前对神经变性中NAD代谢和线粒体功能障碍的理解。更重要的是，由于我们已经表明，在我们的星形胶质细胞-运动神经元共培养系统中鉴定的治疗靶点在转化为ALS动物模型时具有有益效果，因此该提议可能提供调节NAD代谢作为ALS治疗靶点的价值的体内证据。