PerspectiveGene Expression

MicroRNAs silence the noisy genome

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Science  03 Apr 2015:
Vol. 348, Issue 6230, pp. 41-42
DOI: 10.1126/science.aaa9841

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All molecular machines have imperfections, and the biological ones are no exception. One type of flaw is a quantitative one: Although all the cells within an organ are genetically identical, the concentrations of many of their proteins can be “noisy”—that is, vary and fluctuate between all the cells. Biologists decompose such noise into two sources: an intrinsic one, which results from the stochastic nature of the biochemistry operating within cells, and an extrinsic one that manifests global differences between cells, such as the number of protein production facilities (e.g., ribosomes) (1). A major question is whether organisms have evolved means to control noise, especially when imprecisions are detrimental. On page 128 in this issue, Schmiedel et al. (2) report combining mathematical modeling and a synthetic gene approach to establish a complex role for microRNAs (miRNAs) in controlling cellular protein content.