Perturbation of NAD(P)H metabolism with the <i>Lb</i> NOX 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 <i>Drosophila</i> expressing the genetically encoded xenotopic enzyme <i>Lb</i>NOX, which converts NADH to NAD⁺. <i>Lb</i>NOX 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 <i>Lb</i>NOX expression confers stronger protection against paraquat-induced oxidative stress than whole-body expression, emphasizing tissue-dependent redox sensitivity. Notably, <i>Lb</i>NOX expression in nonneuronal tissues restored youthful sleep patterns in aged flies. Together, these findings establish <i>Lb</i>NOX 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.