Changes in RNA in relation to growth of the fibroblast. IV. Alterations in theproduction and processing of mRNA and rRNA in resting and growing cells.
Changes in RNA in relation to growth of the fibroblast. IV. Alterations in theproduction and processing of mRNA and rRNA in resting and growing cells.
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DOI：
10.1083/jcb.71.3.933
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发表时间：
1976-12
期刊：
影响因子：
--
通讯作者：
Penman S
中科院分区：
文献类型：
--
作者：
Johnson LF;Levis R;Abelson HT;Green H;Penman S
以往的报道表明，生长中的3T6成纤维细胞中rRNA和mRNA的浓度和产生速率都高于静息状态的3T6成纤维细胞。对分离的核的研究表明，核糖体RNA的产生显然在转录水平上受到控制。相比之下，被认为是信使核糖核酸前体的hnRNA在静止和生长细胞中的合成速度似乎是相同的。这一发现是出乎意料的，并已通过几种方式进行了测试。在这份报告中，我们通过一种独立的方法表明，生长细胞中mRNA的相对产量比hnRNA的相对产量高出数倍。然而，mRNA的加工动力学似乎没有变化。这一结果表明，mRNA要么来自hnRNA的一小部分，要么是hnRNA前体的加工效率是决定mRNA生产、生长和休息状态的重要控制机制。比较hnRNA和细胞质信息的初始标记率，得出了核质RNA产生细胞质mRNA的效率。非常低的效率(生长细胞中3-4%，静息细胞中1-2%)表明，并不是每个hnRNA分子都能产生细胞质信息。与静息和生长状态下相似的mRNA产生动力学相反，核糖体RNA在静息状态下的加工速度要慢得多，28S RNA从核仁中出现的时间也大大延长。
In previous reports, it was shown that both the concentration and rate of production of rRNA and mRNA were greater in growing than in resting 3T6 fibroblasts. Studies on isolated nuclei indicated that ribosomal RNA production is apparently controlled at the level of transcription. In contrast, hnRNA, the putative precursor of mRNA, appeared to be synthesized at the same rate in resting and growing cells. This finding was unexpected and has been tested in several ways. In this report, we show by an independent method that the relative rate of production of mRNA compared to hnRNA is several-fold higher in growing than in resting cells. However, the kinetics of processing of mRNA appear unchanged. This result suggests either that mRNA arises from a small subfraction of hnRNA or that the efficiency of processing of the hnRNA precursor is an important control mechanism which determines mRNA production ingrowing and resting states. Comparison of the initial rates of labeling of hnRNA and cytoplasmic message gives the efficiency with which the cytoplasmic mRNA is produced from nucleoplasmic RNA.The very low efficiency (3-4% in growing and 1-2% in resting cells) suggests that not every hnRNA molecule gives rise to a cytoplasmic message. In contrast to the similar kinetics of mRNA production in resting and growing states, processing of ribosomal RNA is much slower in the resting state and the emergence time for 28S RNA from nucleolus is greatly lengthened.