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Synthetic biology in mammalian cells: next generation research tools and therapeutics

Key Points

  • Synthetic biology aims to make the engineering of complex biological functions more efficient, reliable and predictable.

  • Recent developments in engineering mammalian cells, on the basis of novel tools such as programmable transcription factors, RNA-based control devices, optogenetic methods and engineered proteins, enable rerouting signalling pathways.

  • High-throughput analysis of synthetic DNA elements and site-directed targeting of chromatin modifiers have revealed insights into gene regulation by sequence- and chromatin-based mechanisms.

  • Analysis of synthetic circuits offers a novel approach to study natural gene networks and protein signalling pathways such as the T cell receptor signalling pathway and kinase cascades.

  • Synthetic biology approaches are helping to improve the specificity of the delivery and activity of therapeutic agents for gene and protein therapies.

  • Enhanced efficiency and safety of engineered systems are leading to exciting therapeutic approaches such as chimeric antigen receptors, microencapsulation of cell-based metabolic control devices and RNA-based vaccines.


Recent progress in DNA manipulation and gene circuit engineering has greatly improved our ability to programme and probe mammalian cell behaviour. These advances have led to a new generation of synthetic biology research tools and potential therapeutic applications. Programmable DNA-binding domains and RNA regulators are leading to unprecedented control of gene expression and elucidation of gene function. Rebuilding complex biological circuits such as T cell receptor signalling in isolation from their natural context has deepened our understanding of network motifs and signalling pathways. Synthetic biology is also leading to innovative therapeutic interventions based on cell-based therapies, protein drugs, vaccines and gene therapies.

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Figure 1: Tools used in mammalian synthetic biology.
Figure 2: Studying chromatin and gene regulation.
Figure 3: Studying gene and signalling networks.
Figure 4: Chimeric antigen receptor therapy.
Figure 5: Prosthetic networks and protein-based therapies.


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The authors apologize to their colleagues whose work could not be cited owing to space limitations. They thank M. Inniss, J. Torella, T. Ford and J. Chen for helpful comments on the manuscript. The work in the author's laboratory was supported by: a European Molecular Biology Organization Fellowship and a Human Frontier Science Program Fellowship to F.L.; a Swiss National Science Foundation Fellowship to A.G.; and funds from NIH and the Defense Advanced Research Projects Agency to P.A.S.

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Correspondence to Pamela A. Silver.

Supplementary information

Supplementary information S1 (table)

Comparison of programmable transcription factors (PDF 591 kb)

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Digital logic gates

Idealized or physical devices that implement Boolean logic (such as AND, OR or NOT) on one or more inputs to produce a single output.


The combination of genetics and optics to control light-sensitive proteins within specific cells.

Directed molecular evolution

A method that mimics the process of natural selection to evolve proteins or nucleic acids towards a user defined goal.


A system is orthogonal when changes to one component do not influence the other components.


Genetic engineering that is based on homologous recombination systems.

Gene dosage compensation

Mechanisms that dampen fluctuations in gene expression levels in response to changes in gene copy numbers.

Xenogeneic cells

Cells that belong to individuals of different species.


The immunologic reactions that occur when T cells are transplanted between two individuals of the same species.

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Lienert, F., Lohmueller, J., Garg, A. et al. Synthetic biology in mammalian cells: next generation research tools and therapeutics. Nat Rev Mol Cell Biol 15, 95–107 (2014).

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