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J. Virol., 01 1998, 180-190, Vol 72, No. 1
P Loser, GS Jennings, M Strauss and V Sandig
The cytomegalovirus (CMV) major immediate-early promoter/enhancer is active
in many cell culture systems and is considered to be one of the strongest
promoters in vitro. However, when this promoter was used in in vivo
approaches to gene therapy, it was silenced within a few weeks in several
organs including the liver. In this study, we demonstrated transcriptional
inactivation of the CMV promoter in mouse liver. In contrast to the CMV
promoter, a hybrid promoter consisting of a minimal CMV promoter and the
enhancer II of hepatitis B virus was active for at least 11 weeks in mouse
liver. While investigating the reason for the shutdown of the CMV promoter,
we did not find evidence for methylation of adenovirus DNA in the region of
transgene insertion, but we could show that the silenced CMV promoter was
reactivated after lipopolysaccharide treatment of mice or partial
hepatectomy. Both stimuli are known to activate the transcription factor
NFkappaB, which binds to four sites in the CMV promoter/enhancer. We show
that expression from the CMV promoter in hepatocyte-derived cell lines in
vitro depends on NFkappaB. In vivo experiments demonstrate that NFkappaB,
which is not present in mouse hepatocytes in vivo, is activated after
infection with recombinant adenoviruses and that the time course of
NFkappaB activation parallels that of CMV promoter- dependent expression.
Moreover, adenovirus infection of transgenic mice carrying a CMV
promoter-driven lacZ gene leads to strong activation of the expression of
this gene in the liver. Thus, NFkappaB is involved in the activation of the
CMV promoter in the liver.
Copyright © 1998, American Society for Microbiology
Reactivation of the previously silenced cytomegalovirus major immediate- early promoter in the mouse liver: involvement of NFkappaB
Department of Molecular Cell Biology, Humboldt-Universitat, Berlin, Germany.
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