New Methods and Technologies J Mol Genet Med (November 2006), 2(1), 107-118 doi: jmgm Published online: 17 July 2006 Full Text: (html | pdf ~966kb | refs) Retroviral vectors containing Tet-controlled bidirectional transcription units for simultaneous regulation of two gene activities Rainer Loew †‡*, Elisa Vigna §, Dirk Lindemann ¶, Luigi Naldini ¥ and Herman Bujard † † Center for Molecular Biology (ZMBH), University Heidelberg, Im Neuenheimer Feld 282, D-69120 Heidelberg, German *Correspondence to: Rainer Loew, Email:rainer.loew@fresenius-biotech.com, Tel: +49 67819855 213, Fax: +49 67819855 284 Received: 03 March 2006, Revised: 06 July 2006, Accepted: 10 July 2006 © Copyright The Authors ----------------------------------------------------------------------------------------------------------------- ABSTRACT In this study retroviral self-inactivating (SIN)-vectors were constructed, that allow simultaneous regulation of two genes by integration of bidirectional Tet controlled transcription units. Marker genes (luciferase and eGFP) were expressed under the control of various bidirectional promoters P tetbis, in order to determine (i) the fraction of HtTA-1 cells exhibiting tight doxycycline (Dox) dependent control; (ii) possible effects of the vector backbone on the regulation of gene transcription; (iii) the possibility for crosstalk between different minimal promoters within P tetbi. When HtTA-1 cells, constitutively expressing the Tet-Transactivator (tTA), were transduced by S2f-lMCg retroviral vector, a high percentage (40) of the cell population displayed tight regulation (5000 fold) of P tetbi activity over a wide range of Dox concentrations. As a result of our comparative study on the activity of virus derived minimal promoters (from MMTV, HIV and CMV), a clear hierarchy of activity as well as a different sensitivity to external influences among the various promoters studied was observed. Furthermore, our results strongly support the idea, that viral elements such as part of the MuLV pol/env region significantly affect the regulation capacity of an integrate. Taking into account our observations as outlined above, we succeeded in generating significantly optimized Tet regulated retroviral vectors. The application of such a one-step transfer system for P tet controlled genes would be of particular relevance to applications where cellular systems do not allow prolonged selection procedures as it is the case with primary cells considered for ex vivo gene therapy. KEYWORDS: Tet-System, bidirectional regulation, retroviral vector, cell populations, minimal promoters ----------------------------------------------------------------------------------------------------------------- Privacy | Disclaimer |