Generation dependent reduction of tTA expression in double transgenic NZL-2/tTACMV mice

• Published in: Genesis (New York, N.Y. : 2000) N.Y. : 2000), 2001-10, Vol.31 (2), p.78-84
• Main Authors: Fedorov, Lev M., Tyrsin, Oleg Yu, Sakk, Olena, Ganscher, Alla, Rapp, Ulf R.
• Format: Article
• Language: English
• Subjects: mRNA; tet system; transcription; transgenic mice; tTA; tTA, mRNA
• ISSN: 1526-954X; 1526-968X
• DOI: 10.1002/gene.10007

Despite the overall successful application of the tet‐system to regulate gene expression in vitro and in vivo, nothing is known so far about the long‐term stability of this system in transgenic mice. In this study, mice of generation F2, F3, F4, or F10 of two independent tTACMV transgenic lines were bred with NZL‐2 mice containing a tTA‐responsive bidirectional promoter that allows the simultaneous expression of two reporter genes encoding luciferase and β‐galactosidase. Analysis of the expression of transgenes in double transgenic mice revealed a dramatic reduction of tTA transactivator mRNA over time. As a consequence, the expression of both reporter genes was gradually reduced from generation to generation in tissues of embryonic and adult NZL‐2/tTACMV mice. Luciferase activity in NZL‐2/tTACMV(F10) mice was reduced 8–10‐fold compared to NZL‐2/ tTACMV(F2) mice, and β‐galactosidase expression was no longer detectable. In summary, we describe the long‐term instability of the tet‐system in our NZL‐2/tTACMV double transgenic mice. The molecular basis of this observation and experimental tools to overcome this limitation need to be addressed in future. genesis 31:78–84, 2001. © 2001 Wiley‐Liss, Inc.