Williams J G, Tsang A S, Mahbubani H
Proc Natl Acad Sci U S A. 1980 Dec;77(12):7171-5. doi: 10.1073/pnas.77.12.7171.
The plasmid pDd812 contains the DNA copy of an mRNA sequence from Dictyostelium discoideum that undergoes first an increase and then a decrease in concentration during the first few hours of differentiation. We have recently shown that the mRNA sequence complementary to pDd812 encodes discoidin I, a developmentally regulated lectin that may play a role in cellular cohesion. By using pDd812 as a hybridization probe, we found that addition of cyclic AMP during the first few hours of development inhibited the accumulation of discoidin I mRNA. By measuring the rate of transcription in isolated nuclei, we showed that, at least in part, this inhibition results from a rapid and specific reduction in the rate of transcription of the discoidin I gene. Addition of cyclic AMP during the first few hours of development inhibited the accumulation of discoidin I mRNA. By measuring the rate of transcription in isolated nuclei, we showed that, at least in part, this inhibition results from a rapid and specific reduction in the rate of transcription of the discoidin I gene. Addition of cyclic AMP during the first few hours of development inhibited the accumulation of discoidin I mRNA. By measuring the rate of transcription in isolated nuclei, we showed that, at least in part, this inhibition results from a rapid and specific reduction in the rate of transcription of the discoidin I gene. Addition of high external concentrations of cAMP is known to increase the intracellular concentration to a level normally found later in development. This natural increase in cAMP concentration occurs at the time during development when transcription of the discoidin I gene ceases. We suggest, therefore, that changes in the intracellular concentration of cAMP act at the level of transcription to control gene expression during development. This hypothesis is supported by our observation that several poly(A)+RNA sequences that normally accumulate after transcription of the discoidin I gene has ceased are synthesized prematurely in cells exposed to exogenous cAMP.
质粒pDd812包含盘基网柄菌mRNA序列的DNA拷贝，该序列在分化的最初几个小时内浓度先升高后降低。我们最近表明，与pDd812互补的mRNA序列编码盘基网柄菌素I，一种受发育调控的凝集素，可能在细胞黏附中起作用。通过使用pDd812作为杂交探针，我们发现发育最初几个小时内添加环磷酸腺苷（cAMP）会抑制盘基网柄菌素I mRNA的积累。通过测量分离细胞核中的转录速率，我们表明，至少部分这种抑制是由于盘基网柄菌素I基因转录速率的快速和特异性降低所致。发育最初几个小时内添加环磷酸腺苷（cAMP）会抑制盘基网柄菌素I mRNA的积累。通过测量分离细胞核中的转录速率，我们表明，至少部分这种抑制是由于盘基网柄菌素I基因转录速率的快速和特异性降低所致。发育最初几个小时内添加环磷酸腺苷（cAMP）会抑制盘基网柄菌素I mRNA的积累。通过测量分离细胞核中的转录速率，我们表明，至少部分这种抑制是由于盘基网柄菌素I基因转录速率的快速和特异性降低所致。已知添加高浓度的细胞外cAMP会使细胞内浓度增加到发育后期通常出现的水平。cAMP浓度的这种自然增加发生在盘基网柄菌素I基因转录停止的发育阶段。因此，我们认为细胞内cAMP浓度的变化在转录水平起作用，以控制发育过程中的基因表达。我们的观察结果支持了这一假设，即在盘基网柄菌素I基因转录停止后通常积累的几个多聚腺苷酸（poly(A)+）RNA序列在暴露于外源性cAMP的细胞中过早合成。
