- Grolla, Ambra A;
- Miggiano, Riccardo;
- Di Marino, Daniele;
- Bianchi, Michele;
- Gori, Alessandro;
- Orsomando, Giuseppe;
- Gaudino, Federica;
- Galli, Ubaldina;
- Del Grosso, Erika;
- Mazzola, Francesca;
- Angeletti, Carlo;
- Guarneri, Martina;
- Torretta, Simone;
- Calabrò, Marta;
- Boumya, Sara;
- Fan, Xiaorui;
- Colombo, Giorgia;
- Travelli, Cristina;
- Rocchio, Francesca;
- Aronica, Eleonora;
- Wohlschlegel, James A;
- Deaglio, Silvia;
- Rizzi, Menico;
- Genazzani, Armando A;
- Garavaglia, Silvia
All cells require sustained intracellular energy flux, which is driven by redox chemistry at the subcellular level. NAD+, its phosphorylated variant NAD(P)+, and its reduced forms NAD(P)/NAD(P)H are all redox cofactors with key roles in energy metabolism and are substrates for several NAD-consuming enzymes (e.g. poly(ADP-ribose) polymerases, sirtuins, and others). The nicotinamide salvage pathway, constituted by nicotinamide mononucleotide adenylyltransferase (NMNAT) and nicotinamide phosphoribosyltransferase (NAMPT), mainly replenishes NAD+ in eukaryotes. However, unlike NMNAT1, NAMPT is not known to be a nuclear protein, prompting the question of how the nuclear NAD+ pool is maintained and how it is replenished upon NAD+ consumption. In the present work, using human and murine cells; immunoprecipitation, pulldown, and surface plasmon resonance assays; and immunofluorescence, small-angle X-ray scattering, and MS-based analyses, we report that GAPDH and NAMPT form a stable complex that is essential for nuclear translocation of NAMPT. This translocation furnishes NMN to replenish NAD+ to compensate for the activation of NAD-consuming enzymes by stressful stimuli induced by exposure to H2O2 or S-nitrosoglutathione and DNA damage inducers. These results indicate that by forming a complex with GAPDH, NAMPT can translocate to the nucleus and thereby sustain the stress-induced NMN/NAD+ salvage pathway.