TNF-α induces MUC1 gene transcription in lung epithelial cells:: its signaling pathway and biological implication
TNF-α induces MUC1 gene transcription in lung epithelial cells:: its signaling pathway and biological implication
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DOI：
10.1152/ajplung.00491.2006
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发表时间：
2007-09-01
影响因子：
4.9
通讯作者：
Kim, K. Chul
中科院分区：
文献类型：
--
作者：
Koga, Takeshi;Kuwahara, Ippei;Kim, K. Chul
本研究旨在阐明TNF-α刺激MUC 1（一种膜系粘蛋白）表达的机制。用TNF-α处理的A549人肺泡细胞与单独用载体处理的细胞相比，在去污剂裂解物中表现出显著更高的MUC 1蛋白水平。与对照组相比，TNF-α处理的细胞中MUC 1蛋白水平的增加与MUC 1 mRNA水平的显著升高相关。然而，TNF-α并没有改变MUC 1转录的稳定性，这意味着增加从头转录诱导的细胞因子。在用启动子-荧光素酶报告质粒转染的A549细胞中，TNF-α增加MUC 1基因启动子活性。MEK 1/2抑制剂U 0126和显性负性ERK 1均阻止TNF-α诱导的MUC 1启动子激活，抗TNFR 1抗体阻断TNF-α刺激的ERK 1/2激活。TNF-α对MUC 1启动子的激活作用也被一种Sp1抑制剂光辉霉素A阻断，同时MUC 1启动子中位于核苷酸-99和-90之间的一个推定的Sp1结合位点的缺失或突变也被阻断。通过染色质免疫沉淀试验证明了在完整细胞中TNF-α刺激的Sp1与MUC 1启动子的结合。我们的结论是TNF-α通过TNFR 1-> MEK 1/2 -> ERK 1-> Sp1途径诱导MUC 1基因转录。
The current study was conducted to elucidate the mechanism through which TNF-alpha stimulates expression of MUC1, a membrane-tethered mucin. A549 human lung alveolar cells treated with TNF-alpha exhibited significantly higher MUC1 protein levels in detergent lysates compared with cells treated with vehicle alone. Increased MUC1 protein levels were correlated with significantly higher levels of MUC1 mRNA in TNF-alpha- treated cells compared with controls. However, TNF-alpha did not alter MUC1 transcript stability, implying increased de novo transcription induced by the cytokine. TNF-alpha increased MUC1 gene promoter activity in A549 cells transfected with a promoter-luciferase reporter plasmid. Both U0126, an inhibitor of MEK1/2, and dominant negative ERK1 prevented TNF-alpha- induced MUC1 promoter activation, and anti-TNFR1 antibody blocked TNF-alpha- stimulated ERK1/2 activation. MUC1 promoter activation by TNF-alpha also was blocked by mithramycin A, an inhibitor of Sp1, as well as either deletion or mutation of a putative Sp1 binding site in the MUC1 promoter located between nucleotides -99 and -90. TNF-alpha- stimulated binding of Sp1 to the MUC1 promoter in intact cells was demonstrated by chromatin immunoprecipitation assay. We conclude that TNF-alpha induces MUC1 gene transcription through a TNFR1 -> MEK1/2 -> ERK1 -> Sp1 pathway.