Study summary · research use only
NAD(+) metabolism governs the proinflammatory senescence-associated secretome
Plain-language summary
Paraphrased from the published abstract below — not a verdict on whether anything works.
In this cell-based study (species not specified), the authors examined how NAD+ metabolism regulates the proinflammatory senescence-associated secretory phenotype (SASP) in senescent cells. Nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme of the NAD+ salvage pathway, was reported to govern the proinflammatory SASP independently of senescence-associated growth arrest, with NAMPT expression regulated by high mobility group A (HMGA) proteins during senescence. The HMGA-NAMPT-NAD+ axis was associated with promotion of the proinflammatory SASP by enhancing glycolysis and mitochondrial respiration, acting through NAD+-mediated suppression of AMPK, which suppressed p53-mediated inhibition of p38 MAPK to enhance NF-kB activity. The authors suggest that, given the tumor-promoting effects associated with the proinflammatory SASP, anti-aging dietary NAD+ augmentation should be considered with caution.
Abstract
Cellular senescence is a stable growth arrest that is implicated in tissue ageing and cancer. Senescent cells are characterized by an upregulation of proinflammatory cytokines, which is termed the senescence-associated secretory phenotype (SASP). NAD+ metabolism influences both tissue ageing and cancer. However, the role of NAD+ metabolism in regulating the SASP is poorly understood. Here, we show that nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme of the NAD+ salvage pathway, governs the proinflammatory SASP independent of senescence-associated growth arrest. NAMPT expression is regulated by high mobility group A (HMGA) proteins during senescence. The HMGA-NAMPT-NAD+ signalling axis promotes the proinflammatory SASP by enhancing glycolysis and mitochondrial respiration. HMGA proteins and NAMPT promote the proinflammatory SASP through NAD+-mediated suppression of AMPK kinase, which suppresses the p53-mediated inhibition of p38 MAPK to enhance NF-κB activity. We conclude that NAD+ metabolism governs the proinflammatory SASP. Given the tumour-promoting effects of the proinflammatory SASP, our results suggest that anti-ageing dietary NAD+ augmentation should be administered with precision.
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