Krupsky M, Fine A, Berk J L, Goldstein R H
Pulmonary Center, Boston University School of Medicine, MA.
Biochim Biophys Acta. 1994 Oct 18;1219(2):335-41. doi: 10.1016/0167-4781(94)90057-4.
We examined alpha 1(I) collagen gene expression in all-trans retinoic acid (RA)-treated human lung fibroblast cultures. RA (10(-5)M) decreased steady-state levels for alpha 1(I) collagen mRNA by at least 75% after 24 h. The inhibition was evident within 8 h after addition of RA, was dose dependent and reversible. Treatment with 9-cis-retinoic acid did not affect alpha 1(I) collagen mRNA levels. RA also inhibited the increases in alpha 1(I) mRNA stimulated by transforming growth factor-beta (TGF-beta). The RA-mediated decrease in alpha 1(I) collagen mRNA was blocked by cycloheximide treatment, suggesting that synthesis of a protein intermediate is required for the inhibition. The RA-induced decrease in alpha 1(I) collagen mRNA levels was not mediated by increases in prostaglandin E2 production. RA decreased alpha 1(I) gene transcription as determined by nuclear run-off assays but did not significantly alter the rate of degradation of the alpha 1(I) transcript as determined by actinomycin D treatment. Studies employing cells stably transfected with constructs containing portions of the alpha 1(I) collagen promoter indicate that the DNA sequences which mediate the inhibitory effect are located within 900 bases from the transcription start site.
我们检测了全反式维甲酸（RA）处理的人肺成纤维细胞培养物中α1（I）型胶原蛋白基因的表达。RA（10^-5M）在24小时后使α1（I）型胶原蛋白mRNA的稳态水平降低了至少75%。在添加RA后的8小时内抑制作用就很明显，呈剂量依赖性且可逆。用9-顺式维甲酸处理不影响α1（I）型胶原蛋白mRNA水平。RA还抑制了转化生长因子-β（TGF-β）刺激引起的α1（I）型mRNA增加。RA介导的α1（I）型胶原蛋白mRNA减少被放线菌酮处理所阻断，这表明抑制作用需要一种蛋白质中间体的合成。RA诱导的α1（I）型胶原蛋白mRNA水平降低不是由前列腺素E2产生增加介导的。通过核转录分析确定RA降低了α1（I）基因转录，但通过放线菌素D处理确定RA并未显著改变α1（I）转录本的降解速率。使用稳定转染了含有α1（I）型胶原蛋白启动子部分构建体的细胞进行的研究表明，介导抑制作用的DNA序列位于转录起始位点900个碱基范围内。
