Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA.
Department of Ophthalmology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA.
Oxid Med Cell Longev. 2020 May 9;2020:2692794. doi: 10.1155/2020/2692794. eCollection 2020.
Nicotinamide adenine dinucleotide (NAD) plays an important role in various key biological processes including energy metabolism, DNA repair, and gene expression. Accumulating clinical and experimental evidence highlights an age-dependent decline in NAD levels and its association with the development and progression of several age-related diseases. This supports the establishment of NAD as a critical regulator of aging and longevity and, relatedly, a promising therapeutic target to counter adverse events associated with the normal process of aging and/or the development and progression of age-related disease. Relative to the above, the metabolism of NAD has been the subject of numerous investigations in various cells, tissues, and organ systems; however, interestingly, studies of NAD metabolism in the retina and its relevance to the regulation of visual health and function are comparatively few. This is surprising given the critical causative impact of mitochondrial oxidative damage and bioenergetic crises on the development and progression of degenerative disease of the retina. Hence, the role of NAD in this tissue, normally and aging and/or disease, should not be ignored. Herein, we discuss important findings in the field of NAD metabolism, with particular emphasis on the importance of the NAD biosynthesizing enzyme NAMPT, the related metabolism of NAD in the retina, and the consequences of NAMPT and NAD deficiency or depletion in this tissue in aging and disease. We discuss also the implications of potential therapeutic strategies that augment NAD levels on the preservation of retinal health and function in the above conditions. The overarching goal of this review is to emphasize the importance of NAD metabolism in normal, aging, and/or diseased retina and, by so doing, highlight the necessity of additional clinical studies dedicated to evaluating the therapeutic utility of strategies that enhance NAD levels in improving vision.
烟酰胺腺嘌呤二核苷酸(NAD)在各种关键的生物过程中发挥着重要作用,包括能量代谢、DNA 修复和基因表达。越来越多的临床和实验证据强调 NAD 水平随年龄的下降及其与多种与年龄相关疾病的发生和发展的相关性。这支持了 NAD 作为衰老和长寿的关键调节剂的建立,以及相关的作为一种有前途的治疗靶点,以对抗与衰老的正常过程和/或与年龄相关疾病的发生和发展相关的不利事件。相对于上述内容,NAD 的代谢已成为各种细胞、组织和器官系统中许多研究的主题;然而,有趣的是,关于 NAD 代谢在视网膜中的研究及其与视觉健康和功能调节的相关性相对较少。鉴于线粒体氧化损伤和生物能危机对视网膜退行性疾病的发展和进展具有关键的致病影响,这令人惊讶。因此,NAD 在该组织中的作用,无论是在正常、衰老和/或疾病情况下,都不应被忽视。本文中,我们讨论了 NAD 代谢领域的重要发现,特别强调了 NAD 生物合成酶 NAMPT 的重要性、视网膜中 NAD 的相关代谢以及 NAMPT 和 NAD 在衰老和疾病中的缺乏或耗竭对该组织的影响。我们还讨论了增强 NAD 水平的潜在治疗策略对上述情况下保留视网膜健康和功能的意义。这篇综述的总体目标是强调 NAD 代谢在正常、衰老和/或患病视网膜中的重要性,并强调需要进行更多的临床研究,以评估增强 NAD 水平的策略在改善视力方面的治疗效用。