Rafferty T S, McKenzie R C, Hunter J A, Howie A F, Arthur J R, Nicol F, Beckett G J
Department of Dermatology, University of Edinburgh, Lauriston Place, Edinburgh EH3 9YW, Scotland, UK.
Biochem J. 1998 May 15;332 ( Pt 1)(Pt 1):231-6. doi: 10.1042/bj3320231.
The generation of reactive oxygen species has been implicated as part of the mechanism responsible for UVB-radiation-induced skin damage. In mice, evidence suggests that increased dietary selenium intake may protect skin from many of the harmful effects of UVB radiation. We sought to determine the selenoprotein profile of cultured human skin cells and whether selenium supplementation could protect keratinocytes and melanocytes from the lethal effects of UVB radiation. Labelling experiments using [75Se]selenite showed qualitative and quantitative differences in selenoprotein expression by human fibroblasts, keratinocytes and melanocytes. This was most noticeable for thioredoxin reductase (60 kDa) and phospholipid glutathione peroxidase (21 kDa); these proteins were identified by Western blotting. Despite these differences, we found that a 24 h preincubation with sodium selenite or selenomethionine protected both cultured human keratinocytes and melanocytes from UVB-induced cell death. With primary keratinocytes, the greatest reduction in cell death was found with 10 nM sodium selenite (79% cell death reduced to 21.7%; P<0.01) and with 50 nM selenomethionine (79% cell death reduced to 13.2%; P<0.01). Protection could be obtained with concentrations as low as 1 nM with sodium selenite and 10 nM with selenomethionine. When selenium was added after UVB radiation, little protection could be achieved, with cell death only being reduced from 88.5% to about 50% with both compounds. In all of the experiments sodium selenite was more potent than selenomethionine at providing protection from UVB radiation.
活性氧的产生被认为是紫外线辐射引起皮肤损伤机制的一部分。在小鼠中，有证据表明增加饮食中硒的摄入量可能保护皮肤免受紫外线辐射的许多有害影响。我们试图确定培养的人皮肤细胞中的硒蛋白谱，以及补充硒是否可以保护角质形成细胞和黑素细胞免受紫外线辐射的致死作用。使用[75Se]亚硒酸盐的标记实验显示，人成纤维细胞、角质形成细胞和黑素细胞在硒蛋白表达上存在定性和定量差异。这在硫氧还蛋白还原酶（60 kDa）和磷脂谷胱甘肽过氧化物酶（21 kDa）中最为明显；这些蛋白质通过蛋白质印迹法鉴定。尽管存在这些差异，但我们发现用亚硒酸钠或硒代蛋氨酸预孵育24小时可保护培养的人角质形成细胞和黑素细胞免受紫外线诱导的细胞死亡。对于原代角质形成细胞，用10 nM亚硒酸钠时细胞死亡减少最多（从79%降至21.7%；P<0.01），用50 nM硒代蛋氨酸时（从79%降至13.2%；P<0.01）。亚硒酸钠低至1 nM、硒代蛋氨酸低至10 nM的浓度即可获得保护作用。当在紫外线辐射后添加硒时，几乎无法实现保护，两种化合物处理后细胞死亡仅从88.5%降至约50%。在所有实验中，亚硒酸钠在提供紫外线辐射防护方面比硒代蛋氨酸更有效。
