Oxidant stress suppresses CFTR expression
Oxidant stress suppresses CFTR expression
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DOI：
10.1152/ajpcell.00070.2005
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发表时间：
2006-01-01
影响因子：
5.5
通讯作者：
Hanrahan, JW
中科院分区：
文献类型：
--
作者：
Cantin, AM;Bilodeau, G;Hanrahan, JW
上皮粘膜反复暴露在氧化剂和外源物质中。Cftr在谷胱甘肽跨上皮通量和确定保护性粘液的水合和粘弹性方面发挥作用。因此，我们推测cftr的表达和功能可能受到氧化应激的调节。亚致死性氧化应激(叔丁基对苯二酚，BHQ)在表达CFTR的上皮细胞(T84)中诱导细胞内谷胱甘肽显著增加，这与编码谷胱甘肽合成限速酶-γ-谷氨酰半胱氨酸合成酶(γ-GCShs)重亚单位的基因表达增加有关。根据反映伽玛-GCShs变化的时间进程，CFTR基因的表达显著降低。Western印迹分析证实，CFTR基因表达的降低与CFTR蛋白的表达降低有关。氧化应激也使cAMP依赖的碘外流减少。核连续实验表明，氧化应激对CFTR基因转录没有影响，但氧化应激细胞的mRNA稳定性明显降低。此外，补肾清能增加CALU-3细胞中的γ-GCshs基因的表达，降低CFTRmRNA的表达，牛磺酸氯胺在T84细胞中也有类似的作用。我们得出结论，抑制CFTR的表达可能代表了粘膜上皮对外源性氧化应激的适应性反应。
Epithelial mucous membranes are repeatedly exposed to oxidants and xenobiotics. CFTR plays a role in glutathione transepithelial flux and in defining the hydration and viscoelasticity of protective mucus. We therefore hypothesized that CFTR expression and function may be modulated by oxidant stress. A sublethal oxidant stress (tert-butylhydroquinone, BHQ) in CFTR-expressing epithelial cells (T84) induced a significant increase in cellular glutathione that was associated with an increase in expression of the gene encoding the heavy subunit of the rate-limiting enzyme for glutathione synthesis, gamma-glutamylcysteine synthetase (gamma-GCShs). CFTR gene expression was markedly decreased according to a time course that mirrored the changes in gamma-GCShs. Western blot analysis confirmed that the decrease in CFTR gene expression was associated with a decrease in CFTR protein. cAMP-dependent iodide efflux was also decreased by the oxidant stress. Nuclear run-on assays indicated that the oxidant stress had no effect on CFTR gene transcription, but the mRNA stability in the oxidant-stressed cells was markedly reduced. Furthermore, BHQ increased gamma-GCShs mRNA while decreasing CFTR mRNA in Calu-3 cells, and taurine chloramine induced similar effects in T84 cells. We conclude that suppression of CFTR expression may represent an adaptive response of mucosal epithelium to an exogenous oxidant stress.