| 摘要: |
| 目的：通过测定人肝癌SMMC-7721细胞酪氨酸转氨酶（TAT）cDNA序列，并观察其糖皮质激素受体（GR）通路是否存在异常，以探讨地塞米松（Dex）丧失诱导SMMC-7721细胞TAT活性的机制。方法：RT-PCR扩增SMMC-7721细胞全长TAT cDNA并进行测序；采用实时定量PCR观察Dex 对SMMC-7721细胞TAT mRNA表达的影响，并与HepG2细胞作对照；采用电穿孔法将GR特异性报告基因GRE-tk-LUC及GRE-MMTV-CAT分别瞬时转入SMMC-7721细胞中，观察Dex对荧光素酶(LUC)和氯酶素乙酰转移酶（CAT）表达的影响，并与HepG2细胞作对照。结果：SMMC-7721细胞TAT cDNA中第576位碱基存在同义突变；Dex能够诱导SMMC-7721细胞中TAT mRNA的表达，最大诱导倍数为2.22，明显低于HepG2细胞（15.1倍，P＜0.01）；Dex诱导了SMMC-7721细胞LUC及CAT的表达，与HepG2细胞无显著差异。结论：Dex对SMMC-7721细胞TAT mRNA诱导水平降低，可能是TAT活性不增高的主要原因。 |
| 关键词: 糖皮质激素 受体 酪氨酸转氨酶 转录激活 |
| DOI：10.3724/SP.J.1008.2008.00630 |
| 投稿时间：2008-01-29修订日期：2008-03-03 |
| 基金项目:国家自然科学基金重点项目（39730210）. |
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| Lost sensibility of tyrosine aminotransferase to dexamethasone in human hepatoma cell line SMMC-7721 |
| LI Yi-dong,LIU Yu-jian,LU Jian* |
| (Department of Pathophysiology,College of Basic Medical Sciences,Second Military Medical University,Shanghai 200433,China) |
| Abstract: |
| Objective:To investigate the mechanism responsible for lost sensibility of tyrosine aminotransferase (TAT) to dexamethasone(Dex) in human hepatoma cell line SMMC-7721 through examining the cDNA sequence of TAT and the status of glucocorticoid receptor (GR) pathway. Methods: The TAT cDNA fragment containing the full length of coding sequence was amplified by reverse transcription-polymerase chain reaction (RT-PCR) and was sequenced.The expression of TAT mRNA was determined by real-time quantitative PCR to observe the influence of Dex on expression of TAT mRNA in SMMC-7721 cells.The experiement with HepG2 cells was performed as the control.Reporter genes (GRE-tk-LUC and GRE-MMTV-CAT) were transiently transfected into SMMC-7721 cells by electroporation.The induction efficiencies of LUC and CAT genes expression by Dex were examined and compared between SMMC-7721 cells and HepG2 cells.Results: The results showed that there was a same-sense mutation (Gln576Gln) in TAT cDNA sequence.TAT mRNA could be induced by Dex,with the maximal induction level being 2.22-folds in SMMC-7721 cells,which was significantly lower than that in HepG2 cells (15.1-fold increase,P＜0.01).Dex induced the expression of LUC and CAT genes in SMMC-7721 cells as well as the HepG2 cells.Conclusion: The induction efficiency of Dex for expression of TAT mRNA is decreased in SMMC-7721 cells,which might be due to the unchanged activity of TAT. |
| Key words: glucocorticoids receptor tyrosine aminotransferase transcriptional activation |
