伴随机体损伤的积累，生物体发生代偿性的代谢重编程和细胞衰老，这是器官衰老的决定性环节。NAD+作为胞内一个核心代谢物，它的水平常常随着器官衰老而显著降低。NAD+的减少加速了器官衰老，而补充NAD+则可延缓衰老的进程。因此，探索NAD+水平作为预测器官衰老的指标以及搜寻上调NAD+水平的先导化合物是本领域的热点问题。然而，利用酶学、色谱和质谱等传统生化分析方法测定NAD+存在严重的技术缺陷，更难以用于高通量筛选。本项目将开发高时空分辨检测NAD+代谢的遗传编码荧光探针，并在单细胞、亚细胞和活体水平建立衰老过程研究的前沿NAD+成像技术，评价NAD+水平作为器官衰老预测指标的潜力，进而将NAD+探针应用于抗衰老化合物的筛选。本项目不仅为生命医学基础研究提供创新性的工具，也为器官衰老的评价以及相关药物的开发提供新的技术支撑和研究手段，因此本研究具有重要的科学意义及社会经济意义。

With the increasing accumulation of damages, living organisms elicit the compensatory responses by metabolic reprogramming together with cellular senescence, which is the critical step toward organismal aging. NAD+ is one of the most important metabolites, whose level decreases with aging. The diminishing NAD+ accelerates the aging process of organs which is significantly delayed by repletion of NAD+. Hence it is of great interest to examine the potential of cellular NAD+ levels as a predictor of aging process as well as seek the compounds raising the NAD+ level. However, traditional methods including enzymatic assays, chromatography and mass spectrometry suffer from some defects in NAD+ assay, and are not suitable for high-throughput screen. The current project aims to develop a novel genetically encoded fluorescent sensor for NAD+ with high spatio-temporal resolution, establishing the state-of-art imaging tool for NAD+ in living organism, single-cell as well as sub-cellular settings. The sensor is also used to evaluate the ability of cellular NAD+ level as an aging indicator and screen the anti-aging candidate compounds. This study will provide a novel tool for basic biomedical research, as well as new insights into the index and drugs for organismal aging, thus it possesses both important scientific significance and economic significance.