RNA-based communication in heterogeneous populations of cell mimics

Abstract RNA regulators offer a promising path for building complex, orthogonal circuits due to their low resource demands and design flexibility. In this study we explore their potential as signaling molecules in communication between synthetic cells. Specifically, we engineer populations of heterogenetic porous polymer cell mimics to produce, emit and receive two types of small synthetic RNA regulators. These RNAs are required to activate reporter expression at both the levels of transcription and translation. We distribute this AND gate circuit in receiver and two types of sender cell mimics to compare the distributed logic computation to the behavior of the circuit in well-mixed, bulk cell-free expression reactions. Analyzing different densities and spatial arrangements of senders and receivers, we reveal spatiotemporal gradients in RNA signals and identify configurations that increase specific activation. With small regulatory RNAs, the engineering toolbox for communication between synthetic cells expands to include a programmable class of signaling molecules. The rapid turnover of RNA suggests applications in establishing dynamic signaling gradients in communities of synthetic cells. Competing Interest Statement The authors have declared no competing interest. Footnotes 1. Clarifications about leaky expression observed for high trigger cell mimic numbers and an extended range for experiments with high trigger cell mimic numbers in Fig. 3 and Fig. S3. 2. Correction of a bug swapping the columns for the STAR and Trigger correlations with respect to radius in Fig. 3C. 3. Expanded explanations and discussion. 4. Predictions of structures and diffusion coefficients for RNA signals. 5. New experimental data on spatially arranged senders.