de Vos S, Brach M, Budnik A, Grewe M, Herrmann F, Krutmann J
Department of Dermatology, Klinikum der Universität Freiburg, Germany.
J Invest Dermatol. 1994 Jul;103(1):92-6. doi: 10.1111/1523-1747.ep12391818.
Exposure to increasing doses (290-315 nm) of ultraviolet (UV) B radiation is thought to profoundly affect human health. Studies on the biologic and molecular effects of UVB radiation on human skin are therefore of particular interest. There is experimental and clinical evidence to assume that UVB radiation-induced local and systemic inflammatory reactions might be mediated at least in part by UVB-induced keratinocyte-derived interleukin (IL)-6. Previously, a UVB-induced increase of steady-state levels of IL-6 mRNA was found to be a prerequisite for keratinocyte IL-6 production after UVB irradiation. The present study was aimed at addressing the question of whether in vitro UVB irradiation would increase IL-6 mRNA expression in long-term cultured, normal human keratinocytes via transcriptional or post-transcriptional mechanisms. UVB exposure (0-100 J/m2) of keratinocytes increased low baseline expression levels of IL-6 mRNA in a time- and dose-dependent manner. Using nuclear run-on assays, transcription rates of the IL-6 gene in nuclei isolated from UVB-irradiated cells were found to be essentially identical to those seen in unirradiated cells, indicating that UVB light did not lead to increased transcription of the IL-6 gene. To determine a possible post-transcriptional mechanism in UVB-induced IL-6 mRNA expression, the effects of UVB irradiation on IL-6 mRNA stability were examined. To this end irradiated and unirradiated keratinocytes were treated with actinomycin D and subjected to Northern blot analysis to calculate IL-6 mRNA half-life. As compared with unirradiated cells, IL-6 mRNA stability was increased significantly (three- to four-fold) in UVB-irradiated cells, suggesting that UVB radiation upregulates IL-6 mRNA levels in human keratinocytes by increasing the stability of IL-6 transcripts. This is the first report indicating that UVB radiation at a physiologically relevant dose may affect gene expression in human cells at a post-transcriptional level.
暴露于剂量不断增加（290 - 315纳米）的紫外线（UV）B辐射被认为会对人类健康产生深远影响。因此，关于UVB辐射对人体皮肤的生物学和分子效应的研究格外引人关注。有实验和临床证据表明，UVB辐射诱导的局部和全身炎症反应可能至少部分是由UVB诱导的角质形成细胞衍生的白细胞介素（IL）-6介导的。此前，发现UVB照射后角质形成细胞IL-6产生的一个先决条件是UVB诱导的IL-6 mRNA稳态水平增加。本研究旨在探讨体外UVB照射是否会通过转录或转录后机制增加长期培养的正常人角质形成细胞中IL-6 mRNA的表达。角质形成细胞暴露于UVB（0 - 100 J/m²）后，IL-6 mRNA的低基线表达水平呈时间和剂量依赖性增加。使用核转录分析，发现从UVB照射细胞中分离的细胞核中IL-6基因的转录率与未照射细胞中的基本相同，这表明UVB光不会导致IL-6基因转录增加。为了确定UVB诱导IL-6 mRNA表达中可能的转录后机制，研究了UVB照射对IL-6 mRNA稳定性的影响。为此，用放线菌素D处理照射和未照射的角质形成细胞，并进行Northern印迹分析以计算IL-6 mRNA半衰期。与未照射细胞相比，UVB照射细胞中IL-6 mRNA稳定性显著增加（三到四倍），这表明UVB辐射通过增加IL-6转录本的稳定性上调人角质形成细胞中IL-6 mRNA水平。这是第一份表明生理相关剂量的UVB辐射可能在转录后水平影响人类细胞基因表达的报告。
