A C. ELEGANS MODEL FOR NMNAT1-MEDIATED HYPOXIC PROTECTION AND LIFESPAN EXTENSION

描述（由申请人提供）：缺氧细胞损伤和轴突变性是美国发病率和死亡率的两个最具破坏性的原因。尽管长期以来的巨大科学努力，没有一种治疗方法被证明在改善人类缺氧损伤或轴突变性方面有效。NAD生物合成酶烟酰胺单核苷酸腺苷转移酶1 （Nmnat1）已被证明可阻断小鼠轴突变性和缺氧损伤。尽管具有深刻的医学相关表型，但Nmnat1保护其免受缺氧损伤或轴突变性的机制尚不清楚。本申请拟利用秀丽隐杆线虫强大的遗传模式生物，建立一种新的模型来研究Nmnat1的细胞保护机制。我实验室的初步实验表明，在秀丽隐杆线虫中表达小鼠Nmnat1的突变形式可以保护线虫免受缺氧损伤。此外，我们发现Nmnat1在秀丽隐杆线虫中的寿命增加了一倍以上，表明Nmnat1具有很强的抗衰老细胞保护功能。本项目将在秀丽隐杆线虫中开发更多的工具来研究小鼠Nmnat1的功能，并回答有关Nmnat1对缺氧损伤和衰老的保护机制的基本问题。aim 1的完成将确定Nmnat1的表达在哪些细胞类型中提供了对缺氧细胞损伤和机体衰老的保护。此外，我们将确定Nmnat1是否仅保护其表达的细胞（细胞自主活性），或者Nmnat1是否保护其不表达的细胞（细胞非自主功能）。Aim 1还将确定Nmnat1何时起保护缺氧和延长寿命的作用，特别是在缺氧损伤之前或之后以及生命的早期或晚期。Aim 2将使用在Aim中产生的转基因菌株来测试我们初步结果提出的特定Nmnat1机制假设。我们将询问Nmnat1的保护作用是否需要线粒体未折叠蛋白反应，以及Nmnat1是否调节线粒体未折叠蛋白反应的活性。这些目标的完成将开发一个强大的新模型来研究这种重要的酶，并可能确定Nmnat1保护缺氧和延长寿命的机制。

DESCRIPTION (provided by applicant): Hypoxic cellular injury and axonal degeneration are two of the most devastating causes of morbidity and mortality in the US. Despite a tremendous longstanding scientific effort, no treatment has proven to be effective at ameliorating either hypoxic injury or axonal degeneration in humans. The NAD biosynthetic enzyme nicotinamide mononucleotide adenylyl transferase 1 (Nmnat1) has been shown to block both axonal degeneration and hypoxic injury in mouse. Despite the profound medically relevant phenotype, the mechanism whereby Nmnat1 protects from either hypoxic injury or axonal degeneration is obscure. This application proposes to utilize the powerful genetic model organism C. elegans to develop a new model to study the cytoprotective mechanisms of Nmnat1. Preliminary experiments from my lab have shown that expression in C. elegans of a mutant form of mouse Nmnat1 protects the nematode from hypoxic injury. In addition, we have discovered that Nmnat1 more than doubles lifespan in C. elegans, demonstrating a strong cytoprotective function of Nmnat1 against aging. This project will develop additional tools in C. elegans to study the function of mouse Nmnat1 and answer fundamental questions about the protective mechanisms of Nmnat1 against hypoxic injury and aging. Completion of aim 1 will determine in what cell types Nmnat1 expression provides protection from hypoxic cellular injury and organismal aging. Additionally, we will determine whether Nmnat1 acts to protect only the cells in which it is expressed (cell autonomous activity) or whether Nmnat1 acts to protect cells in which it is not expressed (cell non-autonomous function). Aim 1 will also define when Nmnat1 functions to protect from hypoxia and extend lifespan, in particular, before or after the hypoxic insult and early or late in life, respectively. Aim 2 will use transgenic strains generated in aim to test a specific Nmnat1 mechanistic hypothesis suggested by our preliminary results. We will ask if the mitochondrial unfolded protein response is required for the protective action of Nmnat1 and whether Nmnat1 regulates the activity of the mitochondrial unfolded protein response. Completion of these aims will develop a powerful new model to study this important enzyme and may define a mechanism whereby Nmnat1 protects from hypoxia and lengthens lifespan.