Kynurenine 3-monooxygenase limits de novo NAD⁺ synthesis through dietary tryptophan in renal proximal tubule epithelial cell models

Nicotinamide adenine dinucleotide (NAD + ) is essential in regulating mitochondrial function. Reduced NAD + synthesis through the de novo pathway is associated with acute kidney injury (AKI). Our study reveals a disruption in de novo NAD + synthesis in proximal tubular models, but not in vivo, attributed to downregulation of enzyme kynurenine 3-monooxygenase (KMO). These findings highlight a crucial role of KMO in governing de novo NAD + biosynthesis within the kidney, shedding light on potential AKI interventions.