Clayton D F, Weiss M, Darnell J E
Mol Cell Biol. 1985 Oct;5(10):2633-41. doi: 10.1128/mcb.5.10.2633-2641.1985.
The transcription rate and abundance of several liver-specific mRNAs as well as mRNAs common to many cell types were compared in a series of rodent hepatoma cell lines, normal liver cells, and primary hepatocyte cultures. The rat hepatoma cell line, Fao, which displays a liver-specific phenotype, contained eight of eight liver-specific mRNAs examined. However, the transcription rates of most liver-specific mRNAs were found to be low (1 to 30%) compared with normal liver in this and other differentiated cell lines. This low rate is similar to the transcription rates of liver-specific mRNA sequences measured in primary cultures of hepatocytes. Several variant cell lines that had lost differentiated traits contained few or none of the liver-specific mRNAs; clonal descendents which had regained differentiated function regained the tissue-specific mRNAs as a group, but at various concentrations. Because all of the changes observed in mRNA levels were not accompanied by parallel changes in transcription of the same sequences, differential posttranscriptional stabilization of the liver-specific mRNAs must also occur in the different cell lines. These results qualify the utility of cultured cell lines in the study of tissue-specific transcriptional control, but raise the possibility that posttranscriptional mechanisms act in cooperation with transcriptional controls to bring the level of tissue-specific mRNAs closer to those found in liver cells.
在一系列啮齿动物肝癌细胞系、正常肝细胞和原代肝细胞培养物中，比较了几种肝脏特异性mRNA以及许多细胞类型共有的mRNA的转录率和丰度。表现出肝脏特异性表型的大鼠肝癌细胞系Fao，在所检测的8种肝脏特异性mRNA中含有8种。然而，在该细胞系和其他分化细胞系中，与正常肝脏相比，大多数肝脏特异性mRNA的转录率较低（1%至30%）。这个低转录率与在肝细胞原代培养物中测得的肝脏特异性mRNA序列的转录率相似。几个已丧失分化特征的变异细胞系含有很少或几乎没有肝脏特异性mRNA；重新获得分化功能的克隆后代作为一个群体重新获得了组织特异性mRNA，但浓度各不相同。由于观察到的mRNA水平的所有变化并未伴随着相同序列转录的平行变化，因此在不同细胞系中也必定发生了肝脏特异性mRNA的差异转录后稳定化。这些结果限制了培养细胞系在组织特异性转录控制研究中的实用性，但也提出了转录后机制与转录控制协同作用以使组织特异性mRNA水平更接近肝细胞中水平的可能性。
