Tetracycline-Responsive Aptazymes Enable Tunable Expression of Self-Amplifying RNA

In self-amplifying RNA, tetracycline-responsive aptazymes inserted in specific regions tune eGFP output, lowering expression up to 2.1-fold at physiologically relevant tetracycline doses.

• Why it matters: Uncontrolled saRNA replication poses safety risks, and simply overexpressing the gene of interest can exhaust cellular resources and increase immunogenic double-stranded RNA.
• What they did: The team tested Tet-On and Tet-Off tetracycline-responsive aptazymes placed in the 3' UTR versus the subgenomic promoter region, and evaluated effects of 33% N1-methyl-pseudouridine substitution.
• The result: Aptazymes in the 3' UTR reduced eGFP, while promoter-region insertion maintained expression; at relevant tetracycline doses, Tet-On and Tet-Off lowered eGFP 1.5-fold and 2.1-fold, respectively, enabling tunable saRNA expression in vitro.

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