Laboratory of Biosystem Dynamics, BioMediTech Institute and Faculty of Biomedical Sciences and Engineering, Tampere University of Technology, 33101, Tampere, Finland.
Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK.
Sci Rep. 2017 Sep 6;7(1):10588. doi: 10.1038/s41598-017-11257-2.
Cell-to-cell variability in cellular components generates cell-to-cell diversity in RNA and protein production dynamics. As these components are inherited, this should also cause lineage-to-lineage variability in these dynamics. We conjectured that these effects on transcription are promoter initiation kinetics dependent. To test this, first we used stochastic models to predict that variability in the numbers of molecules involved in upstream processes, such as the intake of inducers from the environment, acts only as a transient source of variability in RNA production numbers, while variability in the numbers of a molecular species controlling transcription of an active promoter acts as a constant source. Next, from single-cell, single-RNA level time-lapse microscopy of independent lineages of Escherichia coli cells, we demonstrate the existence of lineage-to-lineage variability in gene activation times and mean RNA production rates, and that these variabilities differ between promoters and inducers used. Finally, we provide evidence that this can be explained by differences in the kinetics of the rate-limiting steps in transcription between promoters and induction schemes. We conclude that cell-to-cell and consequent lineage-to-lineage variability in RNA and protein numbers are both promoter sequence-dependent and subject to regulation.
细胞成分的细胞间变异性导致 RNA 和蛋白质产生动力学的细胞间多样性。由于这些成分是遗传的，这也应该导致这些动力学中的谱系间变异性。我们推测这些对转录的影响取决于启动子起始动力学。为了验证这一点，我们首先使用随机模型预测，上游过程（例如从环境中摄取诱导物）中涉及的分子数量的变化仅作为 RNA 产生数量的瞬态变异性的来源，而控制活性启动子转录的分子种类的数量的变化作为一个常数源。接下来，我们通过对大肠杆菌细胞的独立谱系进行单细胞、单 RNA 水平的延时显微镜观察，证明了基因激活时间和平均 RNA 产生率的谱系间变异性的存在，并且这些变异性在启动子和诱导剂之间存在差异。最后，我们提供的证据表明，这可以通过启动子和诱导方案之间转录限速步骤的动力学差异来解释。我们得出的结论是，RNA 和蛋白质数量的细胞间和随后的谱系间变异性既依赖于启动子序列，又受调控。
