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Updated: Jun 25, 2026
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DNA-Tethered RNA Polymerase for Programmable In vitro Transcription and Molecular Computation
Published on: December 29, 2021
Engineering drug-responsive replication machinery for precise control of self-amplifying RNA
Parisa Yousefpour1, Justin R Gregory1, Kristen Si1,2
1Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA.
Nature Biomedical Engineering
|June 23, 2026
Summary
Researchers developed a new self-amplifying RNA (saRNA) system controlled by the drug trimethoprim. This breakthrough allows precise, on-demand gene expression for advanced vaccines and therapies.
Area of Science:
- Molecular Biology
- RNA Therapeutics
- Drug Discovery
Background:
- Self-amplifying RNA (saRNA) offers a potent platform for gene expression but lacks precise, reversible control.
- Existing saRNA systems, including those derived from alphaviruses, have limitations in direct, drug-dependent modulation of their replication machinery.
- Achieving high-fidelity control over saRNA-driven gene expression is crucial for therapeutic applications.
Purpose of the Study:
- To engineer a novel saRNA construct with drug-dependent, reversible control over gene expression.
- To establish a system for precise modulation of saRNA replication using an approved small-molecule drug.
- To evaluate the therapeutic potential of this controllable saRNA platform in preclinical models.
Main Methods:
- Engineered saRNA constructs by fusing drug-responsive degradation domains to non-structural replication proteins.
- Systematically screened different fusion configurations to optimize regulation of self-amplification.
- Utilized trimethoprim as the activating small molecule to control saRNA replication and payload expression.
- Validated the system's performance in vitro and in vivo using a human immunodeficiency virus antigen model in mice.
Main Results:
- Developed saRNA constructs activated by trimethoprim, achieving over 10^4-fold difference between on and off states with minimal background expression.
- Demonstrated tunable, reversible, and temporally programmed gene expression in mice following oral trimethoprim administration.
- Showed that an escalating trimethoprim regimen enhanced germinal center responses when saRNA encoded a human immunodeficiency virus antigen.
Conclusions:
- The engineered drug-regulated saRNA platform provides unprecedented control over gene expression.
- This system offers a clinically compatible strategy for developing advanced vaccines, immunotherapies, and gene therapies.
- The trimethoprim-inducible saRNA technology represents a significant advancement in programmable RNA therapeutics.
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