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. 2013 Dec 23;8(12):e83372. doi: 10.1371/journal.pone.0083372

Figure 3. miRNA as a robust buffer for the synthesis of protein.

Figure 3

Stochastic distribution of the maximum number of messenger RNA and protein molecules in the presence of low (TF = 0.01 in A and B), intermediate (TF = 0.1 in C and D), and large levels of TF (TF = 1 in E and F). For each case, the distribution is calculated with 1000 stochastic cells (see stochastic model for protein expression in Table 3) in the absence of miRNA (V SMIRNA = 0) as well as in the presence of low and high levels of miRNA (V SMIRNA = 0.01 and 0.1). Increasing the level of miRNA reduces the overall level of messenger RNA and protein. Vertical red lines in panels B, D and F indicate the arbitrary threshold of protein (100 protein molecules) needed to promote a cellular response. Regardless of the level of TF, a high level of miRNA, V SMIRNA = 0.1, ensures a robust repression of protein synthesis, which impedes the occurrence of a cellular response; while with low levels of TF, a small level of miRNA, V SMIRNA = 0.01, is already sufficient to prevent stochastic occurrence of protein expression (see panel B). Parameter values are as in Table 2.