Fig. 1

Model and predictions. a Sketch of the minimal model of miRNA–target interactions. One miRNA s and two targets r ₁ and r ₂ are independently transcribed with rates k _s , \(k_{r_{1}}\), and \(k_{r_{2}}\), respectively. Each transcript can then degrade with rate g _s , \(g_{r_{1}}\), or \(g_{r_{2}}\), respectively. Each miRNA s can interact with targets r ₁ or r ₂ with effective binding rates g ₁ or g ₂. α measures the probability of miRNA recycling. If not bound to a miRNA, targets r ₁ and r ₂ can be translated into proteins p ₁ and p ₂, respectively, which could then degrade with rates \(g_{p_{1}}\) and \(g_{p_{2}}\). b–d Predictions from the stochastic model of interactions sketched in (a) as a function of p ₀ (which is the constitutive value of p ₁ when g ₁ tends to 0) in terms of b the mean amount of p ₁ free molecules, c the p ₁ coefficient of variation \({CV}_{p_{1}}\), and d the Pearson correlation coefficient between p ₁ and p ₂. In (b–d), the red curve is the reference curve for a given set of parameters while the red line identifies the threshold. Blue and green curves show how the red curve would move when increasing the interaction strength with the second target g ₂ or the pool of miRNA via the miRNA transcription rate k _s , respectively. e Schematic representation of the two bidirectional plasmids coding for the four fluorophores. miRNA microRNA, UTR untranslated region