Padovan-Merhar Olivia, Nair Gautham P, Biaesch Andrew G, Mayer Andreas, Scarfone Steven, Foley Shawn W, Wu Angela R, Churchman L Stirling, Singh Abhyudai, Raj Arjun
Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA.
Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA.
Mol Cell. 2015 Apr 16;58(2):339-52. doi: 10.1016/j.molcel.2015.03.005. Epub 2015 Apr 9.
Individual mammalian cells exhibit large variability in cellular volume, even with the same absolute DNA content, and so must compensate for differences in DNA concentration in order to maintain constant concentration of gene expression products. Using single-molecule counting and computational image analysis, we show that transcript abundance correlates with cellular volume at the single-cell level due to increased global transcription in larger cells. Cell fusion experiments establish that increased cellular content itself can directly increase transcription. Quantitative analysis shows that this mechanism measures the ratio of cellular volume to DNA content, most likely through sequestration of a transcriptional factor to DNA. Analysis of transcriptional bursts reveals a separate mechanism for gene dosage compensation after DNA replication that enables proper transcriptional output during early and late S phase. Our results provide a framework for quantitatively understanding the relationships among DNA content, cell size, and gene expression variability in single cells.
即使具有相同的绝对DNA含量，单个哺乳动物细胞的细胞体积仍表现出很大的变异性，因此必须补偿DNA浓度的差异，以维持基因表达产物浓度的恒定。通过单分子计数和计算图像分析，我们发现，由于较大细胞中的全局转录增加，转录本丰度在单细胞水平上与细胞体积相关。细胞融合实验表明，细胞内容物的增加本身可以直接增加转录。定量分析表明，这种机制测量的是细胞体积与DNA含量的比率，很可能是通过将一种转录因子隔离到DNA上实现的。对转录爆发的分析揭示了DNA复制后基因剂量补偿的另一种机制，该机制能够在S期早期和晚期实现适当的转录输出。我们的研究结果为定量理解单细胞中DNA含量、细胞大小和基因表达变异性之间的关系提供了一个框架。
