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Molecular and Cellular Biology, October 2008, p. 6066-6077, Vol. 28, No. 19
0270-7306/08/$08.00+0 doi:10.1128/MCB.00246-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.
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Department of Oncology,1 London Regional Cancer Program and The Lawson Health Research Institute, Department of Biochemistry,2 Department of Physiology and Pharmacology, The University of Western Ontario, London, Ontario, Canada3
Received 13 February 2008/ Returned for modification 12 March 2008/ Accepted 4 July 2008
The ZNF217 oncoprotein is a constituent of a core transcriptional complex that includes CoREST, histone deacetylase 1/2, lysine demethylase 1, and the C-terminal binding protein 1/2. We have combined genome-wide expression profiling and chromatin immunoprecipitation with directed selection and ligation (ChIP-DSL) to identify a subset of genes directly regulated by ZNF217. Our results establish p15ink4b as a direct target of the ZNF217 complex. Downregulation of ZNF217 in MCF-7 breast cancer cells resulted in a dramatic increase in p15ink4b expression and coincided with increases in dimethylation of H3-K4 and, surprisingly, a decrease in K9/K14-H3 acetylation. Stimulation of HaCaT cells with transforming growth factor β (TGF-β) resulted in a release of ZNF217 and a concomitant binding of SMAD2 to the proximal promoter, which preceded increases in ink4b protein expression. Furthermore, the changes in chromatin marks at the p15ink4b promoter following TGF-β stimulation were similar to those observed following ZNF217 downregulation. Collectively, these results establish the ZNF217 complex as a novel negative regulator of the p15ink4b gene and may constitute an important link between amplification of ZNF217 and the loss of TGF-β responsiveness in breast cancer.
Published ahead of print on 14 July 2008.
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