瘢痕疙瘩成纤维细胞Smad3、7mRNA表达的调控机制

The modulation of Smad3 mRNA and Smad7 mRNA expression in keloid fibroblasts

目的研究转化生长因子-β1影响瘢痕疙瘩成纤维细胞(KFB)Smad3、7mRNA表达的调控机制。方法用放线菌酮(CHX)和放线菌素D预处理KFB,以分别阻断KFB内源性蛋白质的合成及mRNA合成。采用逆转录PCR法检测瘢痕疙瘩成纤维细胞Smad3、7mRNA表达水平。结果经CHX预处理后,KFB的Smad3mRNA表达轻度上调,并完全抑制了TGF-β1对KFBSmad3mRNA的下调作用(P<0.01);而CHX预处理对KFB的Smad7mRNA表达及TGF-β1上调Smad7mRNA的作用并无明显影响。经放线菌素D预处理后,随TGF-β1作用时间延长,KFB的Smad3mRNA表达水平无明显下降。结论TGF-β1对KFBSmad3mRNA表达的调控过程可能还需要细胞合成其他蛋白的参与;但对Smad7mRNA表达的调控则不需要细胞合成其他蛋白参与,KFB细胞中的Smad7可能也是活化的SMADs的直接靶基因。

Objective To study the modulation of Smad3 mRNA and Smad7 mRNA expression in keloid fibroblasts(KFB) by transforming growth factor-β1(TGF-β1). Methods The de novo protein sythesis and mRNA in KFB were inhibited by pretreatments with cycloheximide(CHX) and actinomycin D.The levels of Smad3 mRNA and Smad7 mRNA expression in KFB were detected by using method of RT-PCR. Results Inhibition of de novo protein synthesis in KFB caused a modest increase in Smad3 mRNA levels;however,delayed down-regulation by TGF-β1 was completely prevented(P<0.01).In contrast,induction of Smad7 mRNA in these cells was unaffected by pretreatment with CHX.The levels of Smad3 mRNA with less differences in untreated and TGF-β1-treated KFB. Conclusion The modulation of Smad3 mRNA expression by TGF-β1 was required de novo protein synthesis,while rapid and transient stimulation of Smad7 mRNA did not require it,suggesting that the Smad7 gene is a direct target of receptor-activated SMAD signals in KFB.