Role of Nuclear NAD in Retinal Homeostasis.

The retina is one of the most metabolically active tissues and maintenance of metabolic homeostasis is critical for retinal function. Nicotinamide adenine dinucleotide (NAD) is a cofactor that is required for key processes, including the electron transport chain, glycolysis, fatty acid oxidation, and redox reactions. NAD also acts as a co-substrate for enzymes involved in maintaining genomic DNA integrity and cellular homeostasis, including poly-ADP ribose polymerases (PARPs) and Sirtuins. This review highlights the importance of NAD in the retina, including the role of enzymes involved in NAD production in the retina and how NAD-consuming enzymes may play a role in disease pathology. We also suggest a cell death pathway that may be common in multiple models of photoreceptor degeneration and highlight the role that NAD likely plays in this process. Finally, we explore future experimental approaches to enhance our understanding of the role of NAD in the retina.