维甲酸对肺纤维化大鼠肺成纤维细胞胶原表达的调控机制

The molecular mechanisms of retinoic acid regulating the expression of collagen by lung fibroblasts in vivo

目的 研究维甲酸 (RA)对肺纤维化大鼠肺成纤维细胞胶原表达的影响及机制。方法 正常组、纤维化组和RA治疗组 3组大鼠分别于肺纤维化模型制备后d 2 8处死 ,取肺组织进行肺成纤维细胞的原代培养。用Northernblot方法检测原代培养肺成纤维细胞前胶原α1(Ⅰ )mRNA表达 ,[3 H] 脯氨酸参入法测定胶原蛋白合成 ,凝胶迁移率法检测核因子AP 1活性 ,RT PCR方法测维甲酸受体的mRNA表达。结果 RA可诱导肺成纤维细胞RXRαmRNA的表达 ,使肺纤维化时增高的AP 1活性下调 ,并抑制前胶原α1(Ⅰ )mRNA表达及胶原蛋白合成。结论 肺纤维化时肺成纤维细胞AP 1活性增高可能是导致胶原过度表达的重要机制。RA可能通过诱导肺成纤维细胞RXRα的表达使增高的AP 1活性得以抑制 ,从而下调胶原基因的表达。

AIM To study the molecular mechanisms of retinoic acid (RA) regulating the expression of collagen produced by lung fibroblasts in vivo. METHOD Rats were divided into control, fibrosis and treatment groups and killed at d 28 after bleomycin administration. The lungs were dissected and cultured for lung fibroblasts. The primarily cultured fibroblasts from different groups were used for determination of levels of procollagen α 1(I) mRNA by Northern blot and the content of collagen protein by [ 3H] proline incorporation assay. The nuclear protein of fibroblasts was also extracted and used for measurement of AP 1 activity by Gel mobility shift assay. The mRNA levels of retinoic acid receptors were determined by RT PCR. RESULT RA induced the expression of RXRα mRNA and down regulated the AP 1 activity which was enhanced in the fibroblasts from fibrosis groups. RA also greatly reduced both the levels procollagen α 1(I) mRNA and the content of collagen protein which were obviously increased in the fibroblasts from rats of fibrosis group. CONCLUSION The enhanced AP 1 activity may play an important role in mediating the overexpression of collagen protein by fibroblasts from fibrosis group. RA reduces the level of procollagen α 1(I) mRNA of fibroblasts by inducing the expression of RXRα which is known to be able to antagonize AP 1 activity.