转化生长因子-β1影响瘢痕疙瘩成纤维细胞Smad3和Smad7 mRNA表达的调控机制

目的研究转化生长因子-β1(TGF-β 1)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 Smad3,7 mRNA表达水平.结果经 CHX预处理后,KFB的 Smad3 mRNA表达轻度上调,并完全抑制了 TGF-β 1对 KFB Smad3 mRNA的下调作用,而CHX预处理对 KFB的 Smad7 mRNA表达及 TGF-β 1上调 Smad7 mRNA的作用并无明显影响.经放线菌素D预处理后,随 TGF-β 1作用时间延长, KFB的 Smad3 mRNA表达水平无明显下降.结论TGF-β 1对 KFB Smad3 mRNA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Smad7 mRNA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.

Modulation mechanism of effects of transforming growth factor-β 1 on Smad3 mRNA and Smad7 mRNA expression of keloid fibroblasts

Aim To study the modulation mechanism of Smad3 mRNA and Smad7 mRNA expression in keloid fibroblasts(KFB) by transforming growth factor-β 1(TGF-β 1).Methods The de novo protein synthesis 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-β 1 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-β 1- treated KFB.Conclusion The modulation of Smad3 mRNA expression by TGF-β 1 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.