Nucleic Acids Research Advance Access published online on April 25, 2008
Nucleic Acids Research, doi:10.1093/nar/gkn208
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Molecular Biology |
Direct inhibition of the DNA-binding activity of POU transcription factors Pit-1 and Brn-3 by selective binding of a phenyl-furan-benzimidazole dication
1INSERM U-837, Team 4-‘Molecular and cellular targeting for cancer treatment’, Jean-Pierre Aubert Research Center, Institut de Recherches sur le Cancer de Lille, Place de Verdun, F-59045 Lille, 2IMPRT-IFR114, Lille, France, 3Department of Chemistry, Georgia State University, Atlanta, GA, USA and 4Institut de Recherches sur le Cancer de Lille - IRCL, Lille, France
*To whom correspondence should be addressed. Tel: + 33 320 16 92 23; Fax: +33 320 16 92 29; Email: marie-helene.david{at}inserm.fr
Received February 5, 2008. Revised April 8, 2008. Accepted April 8, 2008.
The development of small molecules to control gene expression could be the spearhead of future-targeted therapeutic approaches in multiple pathologies. Among heterocyclic dications developed with this aim, a phenyl-furan-benzimidazole dication DB293 binds AT-rich sites as a monomer and 5'-ATGA sequence as a stacked dimer, both in the minor groove. Here, we used a protein/DNA array approach to evaluate the ability of DB293 to specifically inhibit transcription factors DNA-binding in a single-step, competitive mode. DB293 inhibits two POU-domain transcription factors Pit-1 and Brn-3 but not IRF-1, despite the presence of an ATGA and AT-rich sites within all three consensus sequences. EMSA, DNase I footprinting and surface-plasmon-resonance experiments determined the precise binding site, affinity and stoichiometry of DB293 interaction to the consensus targets. Binding of DB293 occurred as a cooperative dimer on the ATGA part of Brn-3 site but as two monomers on AT-rich sites of IRF-1 sequence. For Pit-1 site, ATGA or AT-rich mutated sequences identified the contribution of both sites for DB293 recognition. In conclusion, DB293 is a strong inhibitor of two POU-domain transcription factors through a cooperative binding to ATGA. These findings are the first to show that heterocyclic dications can inhibit major groove transcription factors and they open the door to the control of transcription factors activity by those compounds.