Impact of microRNAs on Cellular Burden

Mammalian synthetic biology has enabled the development of alternative ways to better study biological functions and to design new therapeutics. However, delivery of genetic payloads in mammalian cells can impose a burden on cellular resources, affecting normal cellular physiology and hampering the full exploitation of synthetic devices. Genetic burden has been extensively studied in bacteria where it was demonstrated that a genetic circuit output not always correlates with the amount of input provided due to a limited amount of intracellular resources available for gene expression¹. In this study, we focused on microRNAs (miRNAs) impact on translational burden in mammalian cells. As post-transcriptional regulators, miRNAs shape gene expression addressing target mRNAs and have a role in buffering fluctuations in protein expression². By running quantitative analyses of both target mRNAs and proteins, we determined the presence of translational burden upon expression of genetic payloads and characterized the mechanisms by which non-regulatory interactions shape gene expression in our system. Furthermore, we developed a mathematical model that it is able to recapitulate our experimental findings, providing insights into the key players of cellular burden. Our study pioneers the characterization of cellular burden in mammalian cells and paves the way to more complex circuits design, that could exploit endogenous miRNA levels to modulate gene expression and potentially reverse physiological conditions.

1. Qian, Y. et al. Resource Competition Shapes the Response of Genetic Circuits. ACS Synth. Biol. acssynbio.6b00361 (2017).

1. Siciliano, V. et al. MiRNAs confer phenotypic robustness to gene networks by suppressing biological noise. Nat. Commun. 4, 2364 (2013).