Nucleic Acids Research Advance Access published online on April 16, 2007
Nucleic Acids Research, doi:10.1093/nar/gkm208
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Molecular Biology |
RNA polymerase III transcription is repressed in response to the tumour suppressor ARF
1Institute of Biomedical and Life Sciences, Division of Biochemistry and Molecular Biology, University of Glasgow, Glasgow G12 8QQ and 2Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
*To whom correspondence should be addressed. Tel: +44 141 330 3953; Fax: +44 141 942 6521; Email: r.white{at}beatson.gla.ac.uk
Received February 26, 2007. Revised March 23, 2007. Accepted March 26, 2007.
The tumour suppressor protein ARF provides a defence mechanism against hyperproliferative stresses that can result from the aberrant activation of oncogenes. Accordingly, ARF is silenced or deleted in many human cancers. Activation of ARF can arrest growth and cell cycle progression, or trigger apoptosis. A principle mediator of these effects is p53, which ARF stabilizes by binding and inhibiting MDM2. However, ARF has additional targets and remains able to block growth in the absence of p53, albeit less efficiently. For example, ARF can suppress rRNA production in a p53-independent manner. We have found that the synthesis of tRNA by RNA polymerase III is also inhibited in response to ARF. However, in contrast to its effects on rRNA synthesis, ARF is unable to inhibit tRNA gene transcription when p53 is ablated. These results add to the growing list of cellular changes that can be triggered by ARF induction.