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Duran AG, Schwestka M, Nazari-Shafti TZ, Neuber S, Stamm C, Gossen M. Limiting Transactivator Amounts Contribute to Transgene Mosaicism in Tet-On All-in-One Systems. ACS Synth Biol 2022; 11:2623-2635. [PMID: 35815862 DOI: 10.1021/acssynbio.2c00036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
MicroRNAs play an essential role in cell homeostasis and have been proposed as therapeutic agents. One strategy to deliver microRNAs is to genetically engineer target cells to express microRNAs of interest. However, to control dosage and timing, as well as to limit potential side-effects, microRNAs' expression should ideally be under exogenous, inducible control. Conditional expression of miRNA-based short hairpin RNAs (shRNAmirs) via gene regulatory circuits such as the Tet-system is therefore a promising strategy to control shRNAmirs' expression in research and therapy. Single vector approaches like Tet-On all-in-one designs are more compatible with potential clinical applications by providing the Tet-On system components in a single round of genetic engineering. However, all-in-one systems often come at the expense of heterogeneous and unstable expression. In this study, we aimed to understand the causes that lead to such erratic transgene expression. By using a reporter cell, we found that the degree of heterogeneity mostly correlated with reverse tetracycline transactivator (rtTA) expression levels. Moreover, the targeted integration of a potent rtTA expression cassette into a genomic safe harbor locus functionally rescued previously silenced rtTA-responsive transcription units. Overall, our results suggest that ensuring homogenous and stable rtTA expression is essential for the robust and reliable performance of future Tet-On all-in-one designs.
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Affiliation(s)
- Ana G Duran
- Institute of Active Polymers, Helmholtz-Zentrum Hereon, 14513 Teltow, Germany.,Berlin-Brandenburg School for Regenerative Therapies (BSRT), 13353 Berlin, Germany.,Berlin-Brandenburg Center for Regenerative Therapies (BCRT), 13353 Berlin, Germany.,Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin-Brandenburg Center for Regenerative Therapies, Berlin 13353, Germany
| | - Marko Schwestka
- Institute of Active Polymers, Helmholtz-Zentrum Hereon, 14513 Teltow, Germany.,Berlin-Brandenburg Center for Regenerative Therapies (BCRT), 13353 Berlin, Germany
| | - Timo Z Nazari-Shafti
- Department of Cardiothoracic and Vascular Surgery, German Heart Center Berlin, 13353 Berlin, Germany.,Berlin Institute of Health at Charité - Universitätsmedizin Berlin, BIH Center for Regenerative Therapies, 13353 Berlin, Germany.,German Centre for Cardiovascular Research, Partner Site Berlin, 13353 Berlin, Germany
| | - Sebastian Neuber
- Department of Cardiothoracic and Vascular Surgery, German Heart Center Berlin, 13353 Berlin, Germany.,Berlin Institute of Health at Charité - Universitätsmedizin Berlin, BIH Center for Regenerative Therapies, 13353 Berlin, Germany.,German Centre for Cardiovascular Research, Partner Site Berlin, 13353 Berlin, Germany
| | - Christof Stamm
- Institute of Active Polymers, Helmholtz-Zentrum Hereon, 14513 Teltow, Germany.,Department of Cardiothoracic and Vascular Surgery, German Heart Center Berlin, 13353 Berlin, Germany.,German Centre for Cardiovascular Research, Partner Site Berlin, 13353 Berlin, Germany
| | - Manfred Gossen
- Institute of Active Polymers, Helmholtz-Zentrum Hereon, 14513 Teltow, Germany.,Berlin-Brandenburg Center for Regenerative Therapies (BCRT), 13353 Berlin, Germany
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