Boyer T G, Maquat L E
Department of Human Genetics, Roswell Park Cancer Institute, Buffalo, New York 14263.
J Biol Chem. 1991 Jul 15;266(20):13350-4.
We have monitored the level of mRNA encoding the glycolytic and gluconeogenic enzyme trisephosphate isomerase (TPI) during the growth arrest of cells by serum deprivation and the subsequent growth activation of cells by serum addition. This analysis has demonstrated that the steady state level of TPI mRNA changes 5-20-fold, depending upon the cell type, during the transversal of cells from a proliferative to a nonproliferative state and vice versa. These changes are largely attributable to changes in the rate of TPI gene transcription rather than to alterations in post-transcriptional processes as determined by nuclear run-on measurements. Following serum stimulation, the increase in TPI gene expression is maximal at or around the onset of DNA synthesis. We have also quantitated TPI mRNA throughout the cell cycle following cell synchronization with aphidicolin. Our results indicate that the steady state level of TPI mRNA is relatively constant throughout the division cycle of proliferating cells. Thus, while TPI gene expression is modulated during the traversal of cells to and from a nonproliferative state, it is not significantly modulated during the cycle of events that is characteristic of continuously proliferating cells.
我们监测了编码糖酵解和糖异生酶磷酸丙糖异构酶（TPI）的mRNA水平，监测过程包括通过血清剥夺使细胞生长停滞，以及随后通过添加血清使细胞生长激活。该分析表明，在细胞从增殖状态转变为非增殖状态以及反之亦然的过程中，TPI mRNA的稳态水平会变化5至20倍，具体取决于细胞类型。这些变化很大程度上归因于TPI基因转录速率的变化，而非如通过细胞核连续转录测量所确定的转录后过程的改变。血清刺激后，TPI基因表达的增加在DNA合成开始时或前后达到最大值。我们还在使用阿非迪霉素使细胞同步化后，对整个细胞周期中的TPI mRNA进行了定量。我们的结果表明，在增殖细胞的分裂周期中，TPI mRNA的稳态水平相对恒定。因此，虽然TPI基因表达在细胞往返非增殖状态的过程中受到调节，但在连续增殖细胞特有的事件周期中，它并未受到显著调节。
