Department of Physiology, Bosch Institute, University of Sydney, Sydney, New South Wales, Australia.
Department of Biochemistry, University of California, Riverside, Riverside, California, USA.
J Invest Dermatol. 2013 Mar;133(3):776-782. doi: 10.1038/jid.2012.343. Epub 2012 Sep 27.
UVR produces vitamin D in skin, which is hydroxylated locally to 1α,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)). 1,25(OH)(2)D(3) protects skin cells against UVR-induced DNA damage, including thymine dimers, but the mechanism is unknown. As DNA repair is inhibited by nitric oxide (NO) products but facilitated by p53, we examined whether 1,25(OH)(2)D(3) altered the expression of nitrotyrosine, a product of NO, or p53 after UVR in human keratinocytes. 1,25(OH)(2)D(3) and the nongenomic agonist 1α,25-dihydroxylumisterol(3) reduced nitrotyrosine 16 hours after UVR, detected by a sensitive whole-cell ELISA. p53 was enhanced after UVR, and this was further augmented in the presence of 1,25(OH)(2)D(3). DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid), a chloride channel blocker previously shown to prevent 1,25(OH)(2)D(3)-induced chloride currents in osteoblasts, had no effect on thymine dimers on its own but prevented the 1,25(OH)(2)D(3)-induced protection against thymine dimers. Independent treatment with DIDS, at concentrations that had no effect on thymine dimers, blocked UVR-induced upregulation of p53. In contrast, reduction of nitrotyrosine remained in keratinocytes treated with 1,25(OH)(2)D(3) and DIDS at concentrations shown to block decreases in post-UVR thymine dimers. These results suggest that 1,25(OH)(2)D(3)-induced chloride currents help protect from UVR-induced thymine dimers, but further increases in p53 or reductions of nitrotyrosine by 1,25(OH)(2)D(3) are unlikely to contribute substantially to this protection.
紫外线辐射在皮肤中产生维生素 D，维生素 D 局部被羟化为 1α,25-二羟维生素 D(3)(1,25(OH)(2)D(3))。1,25(OH)(2)D(3) 可保护皮肤细胞免受紫外线辐射引起的 DNA 损伤，包括胸腺嘧啶二聚体，但具体机制尚不清楚。由于一氧化氮（NO）产物会抑制 DNA 修复，但 p53 会促进其修复，因此我们检测了 1,25(OH)(2)D(3) 在紫外线辐射后是否会改变人角质形成细胞中 NO 产物硝基酪氨酸或 p53 的表达。1,25(OH)(2)D(3) 和非基因组激动剂 1α,25-二羟乳甾醇(3)可降低紫外线辐射后 16 小时角质形成细胞中的硝基酪氨酸，通过灵敏的全细胞 ELISA 检测到。紫外线辐射后 p53 增强，在 1,25(OH)(2)D(3)存在下进一步增强。先前的研究表明，氯通道阻滞剂 4,4'-二异硫氰酸基二苯乙烯-2,2'-二磺酸(DIDS)可阻止成骨细胞中 1,25(OH)(2)D(3)诱导的氯离子电流，DIDS 本身对胸腺嘧啶二聚体没有影响，但可防止 1,25(OH)(2)D(3)诱导的对胸腺嘧啶二聚体的保护作用。以不会影响胸腺嘧啶二聚体的浓度单独用 DIDS 处理，可阻断紫外线辐射诱导的 p53 上调。相反，在用 1,25(OH)(2)D(3)和 DIDS 处理的角质形成细胞中，即使在浓度下可阻止紫外线辐射后胸腺嘧啶二聚体减少，硝基酪氨酸的减少仍保持不变。这些结果表明，1,25(OH)(2)D(3)诱导的氯离子电流有助于防止紫外线辐射引起的胸腺嘧啶二聚体形成，但 1,25(OH)(2)D(3)进一步增加 p53 或减少硝基酪氨酸不太可能对这种保护作用有很大贡献。
