Using NAD+ precursor for treatment of global cerebral ischemia

摘要： 心脏骤停或中风引起的缺血性脑损伤是最复杂的病理生理机制之一。 流程。为了成功地治疗缺血性脑损伤，需要针对几个细胞通路和 大脑中的细胞类型。 NAD是参与多种生物能量反应及其降解的重要辅因子 缺血后导致病理性细胞代谢和能量产生抑制。大多数人 通过挽救途径重新合成细胞NAD，其中烟酰胺单核苷酸(NMN) 被转换为NAD。我们最近的研究表明，NMN的管理戏剧性地 改善短暂性全脑缺血后的缺血性脑损伤。此外，NMN 治疗抑制了缺血后NAD的分解代谢，减少了聚ADP-核糖的生成，并逆转了 线粒体过度碎裂。最后，缺血引起的线粒体改变 在注射NMN的动物中，蛋白质乙酰化受到抑制。这一拟议项目的总体目标是 利用NMN开发最有效的治疗策略，显著减少脑缺血 并对其神经保护机制进行了表征。我们假设NMN 脑缺血后给药具有多靶点效应，可显著抑制神经退行性变 以及改善线粒体功能和细胞生物能量学的能力。 具体目标1集中在NMN诱导的调节蛋白质乙酰化的机制上 线粒体的动力学和功能。Sirt1和SIRT3依赖的脱乙酰基在脑内的作用 线粒体融合和分裂将使用我们的转基因动物模型来确定 同时表达针对EYFP和Sirt1或SIRT3的线粒体。此外，SIRT1和SIRT3 基因敲除动物将被用作抑制脱乙酰酶活性的工具。在具体目标2中，我们将 在小鼠全脑缺血后进行NMN给药的时间依赖性研究。我们 将使用无偏见的体视学量化神经细胞死亡，并将进行多项认知测试 以评估治疗效果。恢复期从7天到6天不等 缺血侮辱后几个月。在具体目标3中，我们将确定NMN的神经保护作用 在雌性和老年动物上使用目标2中确定的最具神经保护作用的方案进行治疗。 这项工作的意义在于，它建议将NMN确定为一种保护性化合物， 将显著影响NAD前体作为急性呼吸窘迫综合征治疗化合物的临床应用 并可能揭示神经保护的新靶点。

Summary: Ischemic brain damage due to cardiac arrest or stroke is one of the most complex pathophysiologic processes. To successfully treat ischemic brain injury, one need to target several cellular pathways and cell-type within the brain. NAD+ is an essential cofactor involved in multiple bioenergetic reactions and its degradation after ischemia leads to pathologic cellular metabolism and inhibition of energy production. The majority of cellular NAD+ is re-synthetized via the salvage pathway, where nicotinamide mononucleotide (NMN) is converted to NAD+. Our recent studies demonstrated that administration of NMN dramatically ameliorates ischemic brain injury following transient global cerebral ischemia. Furthermore, NMN treatment inhibited post-ischemic NAD+ catabolism, reduced poly-ADP-ribose generation, and reversed the excessive mitochondrial fragmentation. Finally, the ischemia-induced changes in mitochondrial protein acetylation were inhibited in NMN injected animals. Overall goal of this proposed project is to develop the most effective treatment strategy utilizing NMN that will dramatically reduce ischemic brain damage and characterize the mechanism of its neuroprotection. We hypothesize that NMN administration after ischemia will significantly inhibit neurodegeneration due to its multi-targeted effect and ability to improve mitochondrial functions and cellular bioenergetics. Specific Aim 1 is focused on the NMN-induced protein acetylation mechanisms that modulate mitochondrial dynamics and function. The role of Sirt1 and Sirt3 dependent deacetylation in mitochondrial fusion and fission will be determined using our transgenic animal models that concomitantly express mitochondria targeted eYFP and Sirt1 or Sirt3. Additionally, SIRT1, and SIRT3 knockout animals will be used as tools for inhibition of deacetylase activity. In specific Aim 2, we will perform time-dependent studies of NMN administration following global cerebral ischemia in mice. We will use unbiased stereological quantification of neuronal cell death, and multiple cognitive tests will be performed to assess the efficacy of treatment. The recovery periods will vary from 7 days up to 6 months after ischemic insult. In specific Aim 3, we will determine the neuroprotective effect of the NMN treatment by using the most neuroprotective protocol determined in Aim 2 on female and aged animals. The significance of this work is that it proposes to identify NMN as a protective compound that will significantly impact the clinical application of NAD+ precursors as therapeutic compounds for acute brain injury and potentially reveal new targets for neuroprotection.