Kempe Hermannus, Schwabe Anne, Crémazy Frédéric, Verschure Pernette J, Bruggeman Frank J
Synthetic Systems Biology and Nuclear Organization Group, Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 XH Amsterdam, The Netherlands.
Systems Bioinformatics, Amsterdam Institute for Molecules, Medicines and Systems, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands.
Mol Biol Cell. 2015 Feb 15;26(4):797-804. doi: 10.1091/mbc.E14-08-1296. Epub 2014 Dec 17.
Transcriptional stochasticity can be measured by counting the number of mRNA molecules per cell. Cell-to-cell variability is best captured in terms of concentration rather than molecule counts, because reaction rates depend on concentrations. We combined single-molecule mRNA counting with single-cell volume measurements to quantify the statistics of both transcript numbers and concentrations in human cells. We compared three cell clones that differ only in the genomic integration site of an identical constitutively expressed reporter gene. The transcript number per cell varied proportionally with cell volume in all three clones, indicating concentration homeostasis. We found that the cell-to-cell variability in the mRNA concentration is almost exclusively due to cell-to-cell variation in gene expression activity, whereas the cell-to-cell variation in mRNA number is larger, due to a significant contribution of cell volume variability. We concluded that the precise relationship between transcript number and cell volume sets the biological stochasticity of living cells. This study highlights the importance of the quantitative measurement of transcript concentrations in studies of cell-to-cell variability in biology.
转录随机性可通过计算每个细胞中mRNA分子的数量来衡量。细胞间的变异性最好用浓度而非分子数来描述，因为反应速率取决于浓度。我们将单分子mRNA计数与单细胞体积测量相结合，以量化人类细胞中转录本数量和浓度的统计数据。我们比较了三个仅在相同组成型表达报告基因的基因组整合位点上存在差异的细胞克隆。在所有三个克隆中，每个细胞的转录本数量与细胞体积成比例变化，表明存在浓度稳态。我们发现，mRNA浓度在细胞间的变异性几乎完全归因于基因表达活性在细胞间的差异，而mRNA数量在细胞间的变异性更大，这是由于细胞体积变异性的显著贡献。我们得出结论，转录本数量与细胞体积之间的精确关系决定了活细胞的生物随机性。这项研究强调了在生物学中细胞间变异性研究中转录本浓度定量测量的重要性。
