Activation of a Methylated Promoter Mediated by a Sequence-specific DNA-binding Protein, RFX*
- Melissa I. Niesen‡,
- Aaron R. Osborne‡,
- Hua Yang§¶,
- Shipra Rastogi¶∥,
- Srikumar Chellappan¶∥,
- Jin Q. Cheng§¶,
- Jeremy M. Boss** and
- George Blanckद,1
- Departments of ‡Biochemistry and Molecular Biology, §Pathology, and ∥Interdisciplinary Oncology, College of Medicine, and ¶H. Lee Moffitt Cancer Center and Research Institute, University of South Florida, Tampa, Florida 33612 and the **Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322
- 1 To whom correspondence should be addressed. 12901 Bruce B. Downs, MDC 7, Tampa, FL 33612. Tel.: 813-974-9585, E-mail: gblanck{at}hsc.usf.edu.
Abstract
The roles of eukaryotic DNA methylation in the repression of mRNA transcription and in the formation of heterochromatin have been extensively elucidated over the past several years. However, the role of DNA methylation in transcriptional activation remains a mystery. In particular, it is not known whether the transcriptional activation of methylated DNA is promoter-specific, depends directly on sequence-specific DNA-binding proteins, or is facilitated by the methylation. Here we report that the sequence-specific DNA-binding protein, RFX, previously shown to mediate the transition from an inactive to an active chromatin structure, activates a methylated promoter. RFX is capable of mediating enhanceosome formation on a methylated promoter, thereby mediating a transition from a methylation-dependent repression of the promoter to a methylation-dependent activation of the promoter. These results indicate novel roles for DNA methylation and sequence-specific DNA-binding proteins in transcriptional activation.
Footnotes
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↵2 The abbreviations used are: MBD, methyl-DNA binding domain; MHC, major histocompatibility; IFN-γ, interferon γ; Me-pDRA, methylated pDRA; STAT, signal transducers and activators of transcription; IRF, interferon regulatory factor; MS, mass spectrometry.
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↵* This work was supported by National Institutes of Health Grants R01 CA81497 (to G. B.), R01 CA089242 (to J. Q. C.), R01 CA63136 (to S. C.), and R01 AI34000 and R01 GM47310 (to J. M. B.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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- Received April 27, 2005.
- Revision received August 19, 2005.
- The American Society for Biochemistry and Molecular Biology, Inc.
