Controlled re-activation of epigenetically silenced Tet promoter-driven transgene expression by targeted demethylation. Issue 16 (13th July 2017)

• Record Type: Journal Article
• Authors: Gödecke, Natascha; Zha, Lisha; Spencer, Shawal; Behme, Sara; Riemer, Pamela; Rehli, Michael; Hauser, Hansjörg; Wirth, Dagmar
• Is Part Of: Nucleic acids research. Volume 45:Issue 16(2017)
• Page Start: e147
• Page End: e147
• Publication Date: 2017-07-13
• Subjects: Nucleic acids -- Periodicals; Molecular biology -- Periodicals; 572.805
• DOI: 10.1093/nar/gkx601
• Languages: English
• ISSNs: 0305-1048

Abstract

Abstract: Faithful expression of transgenes in cell cultures and mice is often challenged by locus dependent epigenetic silencing. We investigated silencing of Tet-controlled expression cassettes within the mouse ROSA26 locus. We observed pronounced DNA methylation of the Tet promoter concomitant with loss of expression in mES cells as well as in differentiated cells and transgenic animals. Strikingly, the ROSA26 promoter remains active and methylation free indicating that this silencing mechanism specifically affects the transgene, but does not spread to the host's chromosomal neighborhood. To reactivate Tet cassettes a synthetic fusion protein was constructed and expressed in silenced cells. This protein includes the enzymatic domains of ten eleven translocation methylcytosine dioxygenase 1 (TET-1) as well as the Tet repressor DNA binding domain. Expression of the synthetic fusion protein and Doxycycline treatment allowed targeted demethylation of the Tet promoter in the ROSA26 locus and in another genomic site, rescuing transgene expression in cells and transgenic mice. Thus, inducible, reversible and site-specific epigenetic modulation is a promising strategy for reactivation of silenced transgene expression, independent of the integration site.