Nucleic Acids Research, Vol 25, Issue 17 3445-3450, Copyright © 1997 by Oxford University Press
R Yamamoto, S Koseki, J Ohkawa, K Murakami, S Nishikawa, K Taira and PK Kumar
Regulation of transcription of human immunodeficiency virus type-1 (HIV- 1)
requires specific interaction of Tat protein with the trans- activation
response region (TAR). Inhibition of replication of HIV-1 has previously
been achieved with a TAR decoy, namely a short RNA oligonucleotide that
corresponded to the sequence of the authentic TAR RNA. Since TAR RNA has
the potential to interact with cellular factors, we examined the effect of
TAR RNA on efficiency of transcription in nuclear of HeLa cell extracts. We
performed an in vitro transcription assay in the presence of authentic TAR
RNA using a template that was driven by the CMV (cytomegalovirus) early
promoter in a HeLa nuclear extract and found, for the first time, that TAR
RNA inhibited transcription by approximately 60-70% independently of the
Tat-TAR interaction. Furthermore, we evaluated inhibition of transcription
by variants of TAR RNA and found that the TAR RNA loop, bases surrounding
the loop, the triple base bulge and the 'lower' stem region of TAR RNA were
responsible for the inhibition of transcription. Taken together, earlier
reports on proteins that bind to TAR RNA and the present results suggest
that integrity of TAR RNA is important for efficient binding to cellular
transcription factors. As judged from the significant inhibition observed
in this study, the TAR decoy might sequester transcription factors and thus
it might potentially be able to inhibit transcription of housekeeping genes
that are unrelated to Tat function.
ARTICLES
Inhibition of transcription by the TAR RNA of HIV-1 in a nuclear extract of HeLa cells
National Institute of Bioscience and Human Technology, AIST, MITI, Tsukuba Science City, Ibaraki 305, Japan.
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