甲状腺激素T_3影响K562细胞转铁蛋白受体和铁蛋白表达的分子机制研究

Effect of T_3 on the expression of transferrin receptor and ferritin in K562 cells and its possible mechanism

目的 探讨甲状腺激素T3 对白血病细胞K5 6 2转铁蛋白受体 (TfR)和铁蛋白 (Fn)表达的调控作用及其可能的机制。方法 采用流式细胞术和放射免疫法分别检测TfR和Fn的表达水平 ,用RNA 蛋白带移动分析法测定铁调节蛋白 (IRP)与铁反应元件 (IRE)的结合活性。应用RT PCR方法半定量分析TfR和Fn的mRNA水平。结果 T3 对K5 6 2细胞TfR的表达无明显作用 ,而以不同浓度的T3处理细胞后使Fn的表达增加 ,其中当T3 为 10 0nmol L和 2 0 0nmol L时 ,与空白对照组相比 ,差异有显著性 (P <0 .0 5 )。T3 能减少IRP IRE的结合活性 ,且以T3 为 5 0nmol L时减少最为明显。不同浓度的T3 在不同的作用时间内均能提高H FnmRNA水平 ,而对TfRmRNA水平无显著影响。结论 T3 可增加细胞Fn的表达 ,而对TfR的表达无明显调控作用 ,其机制除包含转录后的调节外 ,可能还具有转录水平的调控作用。

Objective To explore the effect of T 3 on the expression of transferrin receptor(TfR) and ferritin(Fn) in K562 cells and its possible mechanism. Methods Flow cytometry was used for the detection of TfR expression, radioimmunoassay for Fn expression, RNA/protein band shift assay for the binding activity of iron regula-tory protein(IRP) and iron responsive elements(IRE), and RT-PCR for TfR and Fn mRNA levels. Results Different concentration of T 3 significantly increased Fn expression of K562 cells, especially at 100 nmol/L and 200 nmol/L (P<0.05). However, T 3 had no effect on TfR expression. T 3 decreased the binding activity between IRP and IRE, particularly at concentration of 50 nmol/L. Different concentration of T 3 increased Fn-H mRNA level at different time point while it had no effect on TfR mRNA level. Conclusion T 3 increased Fn expression of K562 cells through the possible mechanisms of either the post-transcriptional regulation or transcriptional modulation.