Laboratory of Bioscience & Biotechnology for Cell Function Control, Faculty of Life and Environmental Sciences, Prefectural University of Hiroshima, 5562 Nanatsuka, Shobara, Hiroshima, 727-0023, Japan.
Mol Cell Biochem. 2018 Sep;446(1-2):209-219. doi: 10.1007/s11010-018-3287-y. Epub 2018 Jan 22.
In humans, vitamin C (VC) accumulates at higher concentrations in cells than in plasma, and this intracellular accumulation appears critical to several important physiological functions. However, although VC accumulation decreases in the elderly, the influence of cellular senescence on the transport, accumulation, and function of VC is poorly understood. In this study, we investigated the effects of supplementation with both ascorbic acid (AsA) and dehydroascorbic acid (DehAsA) on the uptake and accumulation of VC, AsA, and DehAsA into cells and the effect of AsA on the levels of intracellular reactive oxygen species (ROS) in human fibroblast TIG-1 cells. We also assessed how that supplementation affected senescence-associated changes in intracellular VC transport and accumulation. AsA supplementation significantly increased intracellular levels of AsA, DehAsA, and total VC (i.e., reduced AsA plus oxidized DehAsA) in senescent cells compared with young cells. DehAsA supplementation also significantly increased intracellular AsA and total VC levels in senescent cells, but not DehAsA, and the increases were less than after adding AsA. Among the molecules related to VC accumulation, the mRNA and protein expressions of sodium-dependent VC transporter 2 (SLC23A2) were increased in senescent cells. Furthermore, intracellular peroxide and superoxide anion levels were higher in senescent cells, with AsA supplementation markedly attenuating spontaneous intracellular peroxide accumulation. Overall, our results therefore suggest that VC transport and accumulation improved in senescent human fibroblast TIG-1 cells due to the adaptive upregulation of sodium-dependent VC transporter 2 in response to increased ROS levels. We conclude that adequate supplementation with AsA can effectively mitigate senescence-associated intracellular ROS.
在人类中，维生素 C（VC）在细胞中的浓度比在血浆中高，这种细胞内积累对几种重要的生理功能至关重要。然而，尽管老年人的 VC 积累减少，但细胞衰老对 VC 的转运、积累和功能的影响知之甚少。在这项研究中，我们研究了补充抗坏血酸（AsA）和脱氢抗坏血酸（DehAsA）对 VC、AsA 和 DehAsA进入细胞的摄取和积累的影响，以及 AsA 对人成纤维细胞 TIG-1 细胞内活性氧（ROS）水平的影响。我们还评估了补充剂如何影响细胞内 VC 转运和积累的衰老相关变化。与年轻细胞相比，AsA 补充剂显著增加了衰老细胞内的 AsA、DehAsA 和总 VC（即减少的 AsA 加上氧化的 DehAsA）水平。DehAsA 补充剂也显著增加了衰老细胞内的 AsA 和总 VC 水平，但不能增加 DehAsA，并且增加幅度小于添加 AsA 后。在与 VC 积累相关的分子中，钠离子依赖的 VC 转运体 2（SLC23A2）的 mRNA 和蛋白表达在衰老细胞中增加。此外，衰老细胞内的过氧化物和超氧阴离子水平较高，AsA 补充剂显著减弱了自发的细胞内过氧化物积累。总的来说，我们的结果表明，由于 ROS 水平升高导致钠离子依赖的 VC 转运体 2 的适应性上调，衰老的人成纤维细胞 TIG-1 细胞中的 VC 转运和积累得到改善。我们得出结论，适当补充 AsA 可以有效减轻与衰老相关的细胞内 ROS。
