Robustness in miRNA-based circuits
Silvia Grigolon (Laboratoire Jean Perrin, Sorbonne U.)
Phenotypic differentiation often relies on bimodal distributions of gene expression levels, which can normally be achieved by different molecular mechanisms. During the past decades microRNAs, small noncoding RNA molecules, were found to downregulate the expression of preferred mRNA targets by sequestering and successively degrading them, thus influencing the level of gene expression. In this talk, I will show how miRNAs play an important role in filtering noise in gene expression. Starting from purely intrinsic noise, I will talk about how this can be buffered by miRNAs, which yet become apparently inefficient in the presence of sources of extrinsic noise. I will then theoretically address the question on how microRNA-mediated regulation can induce the appearance of bimodal phenotypes. Our findings show that the presence of extrinsic noise favours bimodal distributions. This suggests a simple mechanism for obtaining bimodal populations where the presence of extrinsic noise relaxes the requirements on parameters fine tuning.