Transcriptional activation by tetracyclines in mammalian cells
Key findings
Introduced the reverse tetracycline transactivator (rtTA), enabling the Tet-On system. A mutant Tet repressor was fused to VP16 such that the resulting rtTA only binds tetO sequences in the presence of doxycycline—the opposite logic of the original tTA (Tet-Off). Addition of doxycycline to HeLa cells constitutively expressing rtTA induced a stably integrated reporter more than 1,000-fold. This inverted pharmacology (drug-on = gene-on) is operationally preferred for in vivo applications where baseline silencing is required without drug administration. The rtTA/TRE pair is the dominant inducible regulatory design used in AAV vectors requiring conditional or titratable transgene expression.