We tested the hypothesis that 1,25-dihydroxyvitamin D₃ [1α,25(OH)₂ D₃ ] has antiaging effects via upregulating nuclear factor (erythroid-derived 2)-like 2 (Nrf2), reducing reactive oxygen species (ROS), decreasing DNA damage, reducing p16/Rb and p53/p21 signaling, increasing cell proliferation, and reducing cellular senescence and the senescence-associated secretory phenotype (SASP). We demonstrated that 1,25(OH)₂ D₃ -deficient [1α(OH)ase^-/- ] mice survived on average for only 3 months. Increased tissue oxidative stress and DNA damage, downregulated Bmi1 and upregulated p16, p53 and p21 expression levels, reduced cell proliferation, and induced cell senescence and the senescence-associated secretory phenotype (SASP) were observed. Supplementation of 1α(OH)ase^-/- mice with dietary calcium and phosphate, which normalized serum calcium and phosphorus, prolonged their average lifespan to more than 8 months with reduced oxidative stress and cellular senescence and SASP. However, supplementation with exogenous 1,25(OH)₂ D₃ or with combined calcium/phosphate and the antioxidant N-acetyl-l-cysteine prolonged their average lifespan to more than 16 months and nearly 14 months, respectively, largely rescuing the aging phenotypes. We demonstrated that 1,25(OH)₂ D₃ exerted an antioxidant role by transcriptional regulation of Nrf2 via the vitamin D receptor (VDR). Homozygous ablation of p16 or heterozygous ablation of p53 prolonged the average lifespan of 1α(OH)ase^-/- mice on the normal diet from 3 to 6 months by enhancing cell proliferative ability and reducing cell senescence or apoptosis. This study suggests that 1,25(OH)₂ D₃ plays a role in delaying aging by upregulating Nrf2, inhibiting oxidative stress and DNA damage，inactivating p53-p21 and p16-Rb signaling pathways, and inhibiting cell senescence and SASP.

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