Harned J, Grimes A M, McGahan M C
Department of Molecular Biomedical Sciences, North Carolina State University, Raleigh, NC 27606, USA.
Photochem Photobiol. 2003 Apr;77(4):440-5.
Ferritin is a multimeric protein consisting of heavy and light chains assembled in different tissue-specific ratios, which can protect cells from oxidative stress by storing reactive iron (Fe). Because the lens is constantly exposed to UV irradiation, we studied its effects on ferritin synthesis and Fe metabolism in cultured lens epithelial cells with and without ascorbic acid (Asc). UVB caused a large increase in accumulation of newly synthesized ferritin chains; this increase was additive to that induced by Asc. In contrast to the Asc-induced increase in Fe storage, Fe storage in ferritin was unaltered by UVB. Although UVB increased accumulation of newly synthesized ferritin chains, total ferritin levels were unaltered. In contrast, Asc, which induced a quantitatively similar increase in accumulation of newly synthesized ferritin chains, doubled the total amount of ferritin. Because UVB did not change Fe storage in ferritin or the size of the labile Fe pool, it was hypothesized and then determined that these newly synthesized chains did not assemble into functional holoferritin. Numerous studies detail the effects of various treatments on de novo ferritin synthesis; however, this study provides a cautionary note regarding the conclusions of such studies in the absence of data indicating assembly of functional ferritin molecules.
铁蛋白是一种多聚体蛋白，由重链和轻链以不同的组织特异性比例组装而成，它可以通过储存活性铁（Fe）来保护细胞免受氧化应激。由于晶状体不断受到紫外线照射，我们研究了其对添加和不添加抗坏血酸（Asc）的培养晶状体上皮细胞中铁蛋白合成和铁代谢的影响。紫外线B（UVB）导致新合成的铁蛋白链积累大幅增加；这种增加是Asc诱导增加的叠加效应。与Asc诱导的铁储存增加相反，UVB对铁蛋白中的铁储存没有影响。虽然UVB增加了新合成的铁蛋白链的积累，但铁蛋白的总水平没有改变。相比之下，Asc诱导新合成的铁蛋白链积累增加的量相似，但使铁蛋白的总量增加了一倍。由于UVB没有改变铁蛋白中的铁储存或不稳定铁池的大小，因此推测并确定这些新合成的链没有组装成功能性全铁蛋白。许多研究详细阐述了各种处理对从头合成铁蛋白的影响；然而，本研究对在缺乏表明功能性铁蛋白分子组装的数据的情况下此类研究的结论提出了警示。
