A Platform for Synthetic, Orthogonal, Intercellular Communication via Synthetikines

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Rachel Dudek, Nichole M. Daringer (Northwestern University Department of Chemical and Biological Engineering) , Joshua N. Leonard ( Northwestern University Department of Chemical and Biological Engineering; Chemistry of Life Processes Institute; Member, Robert H. Lurie Comprehensive Cancer Center)

Northwestern University Department of Chemical and Biological Engineering, United States

A technology enabling the transmission of independent, synthetic, high information content signals between cells in a multicellular network remains a grand challenge in mammalian synthetic biology. This capability could enable the construction of networks involving division of labor, spatial organization, and coordinated functions eventually leading to applications including regenerative medicine and tissue engineering, as well as new tools for fundamental research. Protein-based signaling mediators are well-suited to this role, and molecules such as cytokines and chemokines serve exactly this function in natural regulation of multicellular organisms. However, to date we lack synthetic biology ligand-receptor platforms suitable to sending and receiving protein-based signals. To meet this need, we have developed a novel orthogonal signaling platform of modular synthetic cytokines (which we have termed, “synthetikines”) and corresponding modular synthetic receptors that can detect and discriminate between these signaling molecules. We show how modular receptor design enables both the use of orthogonal signal transduction mechanisms and optimization of desirable receptor performance characteristics. Our synthetikine networks recapitulate both paracrine signaling (i.e., via secretion of soluble ligands) and juxtacrine signaling (i.e., by cell surface-bound ligands), each of which play key roles in processes such as homeostasis and development. Here, we characterize a foundational platform based on mammalian cells, although the core technology could also be adapted to enable interkingdom signaling (e.g., for interrogating or manipulating interactions between host and bacteria in the gut). This novel capability in the mammalian synthetic biology toolkit should prove useful for both investigating and implementing design principles for engineering synthetic multicellular networks.