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A SILAC-Based Screen for Methyl-CpG Binding Proteins Identifies RBP-J as a DNA Methylation and Sequence-Specific Binding Protein

BACKGROUND: DNA methylation is an epigenetic modification that plays a crucial role in a variety of biological processes. Methylated DNA is specifically bound by Methyl-CpG Binding Proteins (MBPs). Three different types of MBPs have been identified so far: the Methyl-CpG Binding Domain (MBD) family...

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Detalles Bibliográficos
Autores principales: Bartels, Stefanie J. J., Spruijt, Cornelia G., Brinkman, Arie B., Jansen, Pascal W. T. C., Vermeulen, Michiel, Stunnenberg, Hendrik G.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2011
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3185043/
https://www.ncbi.nlm.nih.gov/pubmed/21991380
http://dx.doi.org/10.1371/journal.pone.0025884
Descripción
Sumario:BACKGROUND: DNA methylation is an epigenetic modification that plays a crucial role in a variety of biological processes. Methylated DNA is specifically bound by Methyl-CpG Binding Proteins (MBPs). Three different types of MBPs have been identified so far: the Methyl-CpG Binding Domain (MBD) family proteins, three BTB/POZ-Zn-finger proteins, and UHRF1. Most of the known MBPs have been identified via homology with the MBD and Zn-finger domains as present in MeCP2 and Kaiso, respectively. It is conceivable that other proteins are capable of recognizing methylated DNA. METHODOLOGY/PRINCIPAL FINDINGS: For the purpose of identifying novel ‘readers’ we set up a methyl-CpG pull-down assay combined with stable-isotope labeling by amino acids in cell culture (SILAC). In a methyl-CpG pull-down with U937 nuclear extracts, we recovered several known MBPs and almost all subunits of the MBD2/NuRD complex as methylation specific binders, providing proof-of-principle. Interestingly, RBP-J, the transcription factor downstream of Notch receptors, also bound the DNA in a methylation dependent manner. Follow-up pull-downs and electrophoretic mobility shift assays (EMSAs) showed that RBP-J binds methylated DNA in the context of a mutated RBP-J consensus motif. CONCLUSIONS/SIGNIFICANCE: The here described SILAC/methyl-CpG pull-down constitutes a new approach to identify potential novel DNAme readers and will advance unraveling of the complete methyl-DNA interactome.