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Mol. Cell. Biol., Nov 1995, 6246-6255, Vol 15, No. 11
AD Bailey, Z Li, T Pavelitz and AM Weiner
Infection of human cells with oncogenic adenovirus type 12 (Ad12) induces
four specific chromosome fragile sites. Remarkably, three of these sites
appear to colocalize with tandem arrays of genes encoding small, abundant,
ubiquitously expressed structural RNAs--the RNU1 locus encoding U1 small
nuclear RNA (snRNA), the RNU2 locus encoding U2 snRNA, and the RN5S locus
encoding 5S rRNA. Recently, an artificial tandem array of the natural
5.8-kb U2 repeat unit has been shown to generate a new Ad12-inducible
fragile site (Y.-P. Li, R. Tomanin, J. R. Smiley, and S. Bacchetti, Mol.
Cell. Biol. 13:6064-6070, 1993), demonstrating that the U2 repeat unit
alone is sufficient for virally induced fragility. To identify elements
within the U2 repeat unit that are required for virally induced fragility,
we generated cell lines containing artificial tandem arrays of the entire
5.8-kb repeat unit, an 834-bp fragment spanning the U2 gene alone, or the
same 834-bp fragment from which key U2 transcriptional regulatory elements
had been deleted. The U2 snRNA coding regions within each artificial array
were marked by an innocuous single base change (U to C at position 87) so
that the relative expression of supernumerary and endogenous U2 genes could
be monitored by a primer extension assay. We find that artificial arrays of
both the 5.8- and the 0.8-kb U2 repeat units are fragile but that arrays
lacking either the distal sequence element or both the distal and the
proximal sequence elements of the promoter are not. Surprisingly,
variations in repeat copy number and/or transcriptional activity of the
artificial arrays do not appear to correlate with the degree of
Ad12-inducible fragility. We conclude that U2 transcriptional regulatory
elements are required for virally induced fragility but not necessarily U2
snRNA transcription per se.
Copyright © 1995, American Society for Microbiology
Adenovirus type 12-induced fragility of the human RNU2 locus requires U2 small nuclear RNA transcriptional regulatory elements
Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520-8024, USA.
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