Direct homo- and hetero-interactions of MeCP2 and MBD2

PLoS One. 2013;8(1):e53730. doi: 10.1371/journal.pone.0053730. Epub 2013 Jan 15.

Abstract

Epigenetic marks like methylation of cytosines at CpG dinucleotides are essential for mammalian development and play a major role in the regulation of gene expression and chromatin architecture. The methyl-cytosine binding domain (MBD) protein family recognizes and translates this methylation mark. We have recently shown that the level of MeCP2 and MBD2, two members of the MBD family, increased during differentiation and their ectopic expression induced heterochromatin clustering in vivo. As oligomerization of these MBD proteins could constitute a factor contributing to the chromatin clustering effect, we addressed potential associations among the MBD family performing a series of different interaction assays in vitro as well as in vivo. Using recombinant purified MBDs we found that MeCP2 and MBD2 showed the stronger self and cross association as compared to the other family members. Besides demonstrating that these homo- and hetero-interactions occur in the absence of DNA, we could confirm them in mammalian cells using co-immunoprecipitation analysis. Employing a modified form of the fluorescent two-hybrid protein-protein interaction assay, we could clearly visualize these associations in single cells in vivo. Deletion analysis indicated that the region of MeCP2 comprising amino acids 163-309 as well the first 152 amino acids of MBD2 are the domains responsible for MeCP2 and MBD2 associations. Our results strengthen the possibility that MeCP2 and MBD2 direct interactions could crosslink chromatin fibers and therefore give novel insight into the molecular mechanism of MBD mediated global heterochromatin architecture.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Chromatin / metabolism
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Gene Expression
  • Humans
  • Methyl-CpG-Binding Protein 2 / chemistry
  • Methyl-CpG-Binding Protein 2 / genetics
  • Methyl-CpG-Binding Protein 2 / metabolism*
  • Mice
  • Protein Binding
  • Protein Interaction Domains and Motifs
  • Protein Interaction Mapping

Substances

  • Chromatin
  • DNA-Binding Proteins
  • MBD2 protein
  • Methyl-CpG-Binding Protein 2

Grant support

This work was funded by grants of the Deutsche Forschungsgemeinschaft [DFG SPP 1356 and 1129] (URL: www.dfg.de) and the Bundesministerium für Forschung und Technik BMBF [02S8355] (URL: www.bmbf.de). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.