The Laboratory of Physiological Hygiene and Exercise Science, School of Kinesiology, University of Minnesota Twin Cities, Minneapolis, MN 55455, USA.
Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN 55905, USA.
Cells. 2022 Feb 17;11(4):710. doi: 10.3390/cells11040710.
Nicotinamide adenine dinucleotide (NAD) is a versatile chemical compound serving as a coenzyme in metabolic pathways and as a substrate to support the enzymatic functions of sirtuins (SIRTs), poly (ADP-ribose) polymerase-1 (PARP-1), and cyclic ADP ribose hydrolase (CD38). Under normal physiological conditions, NAD+ consumption is matched by its synthesis primarily via the salvage pathway catalyzed by nicotinamide phosphoribosyltransferase (NAMPT). However, aging and muscular contraction enhance NAD+ utilization, whereas NAD+ replenishment is limited by cellular sources of NAD+ precursors and/or enzyme expression. This paper will briefly review NAD+ metabolic functions, its roles in regulating cell signaling, mechanisms of its degradation and biosynthesis, and major challenges to maintaining its cellular level in skeletal muscle. The effects of aging, physical exercise, and dietary supplementation on NAD+ homeostasis will be highlighted based on recent literature.
烟酰胺腺嘌呤二核苷酸（NAD）是一种用途广泛的化学化合物，作为代谢途径中的辅酶，以及支持沉默调节蛋白（SIRTs）、多聚（ADP-核糖）聚合酶-1（PARP-1）和环 ADP 核糖水解酶（CD38）的酶促功能的底物。在正常生理条件下，NAD+的消耗与其合成相匹配，主要通过烟酰胺磷酸核糖转移酶（NAMPT）催化的补救途径进行。然而，衰老和肌肉收缩会增强 NAD+的利用，而 NAD+的补充则受到细胞内 NAD+前体的来源和/或酶表达的限制。本文将简要回顾 NAD+的代谢功能，其在调节细胞信号转导中的作用，其降解和生物合成的机制，以及维持骨骼肌中 NAD+细胞水平的主要挑战。基于最近的文献，将重点介绍衰老、体育锻炼和饮食补充对 NAD+动态平衡的影响。
