Perturbation of NAD(P)H metabolism with the LbNOX xenotopic tool extends lifespan and mitigates age-related changes

Aging involves widespread metabolic dysregulation, including a decline in total nicotinamide adenine dinucleotide (NAD) levels. While NAD precursor supplementation elevates total NAD levels, it does not reveal tissue-specific effects of an altered NADH [reduced form of NAD⁺ (oxidized NAD)]/NAD⁺ balance. To address this, we generated transgenic Drosophila expressing the genetically encoded xenotopic enzyme LbNOX, which converts NADH to NAD⁺. LbNOX expression modulated both NAD(H) and NADP(H) (reduced form of NAD phosphate) metabolites in a sex-dependent manner and rescued neuronal cell death induced by mutant αB-crystallin-associated reductive stress. We demonstrate that tissue-specific targeting of redox NAD metabolism shows distinct outcomes: Muscle-specific LbNOX expression confers stronger protection against paraquat-induced oxidative stress than whole-body expression, emphasizing tissue-dependent redox sensitivity. Notably, LbNOX expression in nonneuronal tissues restored youthful sleep patterns in aged flies. Together, these findings establish LbNOX as an efficient xenotopic tool for in vivo redox manipulation and reveal tissue- and sex-specific NAD(P)H mechanisms underlying aging, stress resilience, and sleep regulation, providing a framework for NAD-based interventions in aging.