title: MeCP2 binds to nucleosome free (linker DNA) regions and to H3K9/H3K27 methylated nucleosomes in the brain.
abstract: Methyl-CpG-binding protein 2 (MeCP2) is a chromatin-binding protein that mediates transcriptional regulation, and is highly abundant in brain. The nature of its binding to reconstituted templates has been well characterized in vitro. However, its interactions with native chromatin are less understood. Here we show that MeCP2 displays a distinct distribution within fractionated chromatin from various tissues and cell types. Artificially induced global changes in DNA methylation by 3-aminobenzamide or 5-aza-2'-deoxycytidine, do not significantly affect the distribution or amount of MeCP2 in HeLa S3 or 3T3 cells. Most MeCP2 in brain is chromatin-bound and localized within highly nuclease-accessible regions. We also show that, while in most tissues and cell lines, MeCP2 forms stable complexes with nucleosome, in brain, a fraction of it is loosely bound to chromatin, likely to nucleosome-depleted regions. Finally, we provide evidence for novel associations of MeCP2 with mononucleosomes containing histone H2A.X, H3K9me(2) and H3K27me(3) in different chromatin fractions from brain cortex and in vitro. We postulate that the functional compartmentalization and tissue-specific distribution of MeCP2 within different chromatin types may be directed by its association with nucleosomes containing specific histone variants, and post-translational modifications.
authors.affiliation: Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 3P6.
authors.forename: Anita A
authors.initials: AA
authors.lastname: Thambirajah
authors.forename: Marlee K
authors.initials: MK
authors.lastname: Ng
authors.forename: Lindsay J
authors.initials: LJ
authors.lastname: Frehlick
authors.forename: Andra
authors.initials: A
authors.lastname: Li
authors.forename: Jason J
authors.initials: JJ
authors.lastname: Serpa
authors.forename: Evgeniy V
authors.initials: EV
authors.lastname: Petrotchenko
authors.forename: Begonia
authors.initials: B
authors.lastname: Silva-Moreno
authors.forename: Kristal K
authors.initials: KK
authors.lastname: Missiaen
authors.forename: Christoph H
authors.initials: CH
authors.lastname: Borchers
authors.forename: J
authors.initials: J
authors.lastname: Adam Hall
authors.forename: Ryan
authors.initials: R
authors.lastname: Mackie
authors.forename: Frank
authors.initials: F
authors.lastname: Lutz
authors.forename: Brent E
authors.initials: BE
authors.lastname: Gowen
authors.forename: Michael
authors.initials: M
authors.lastname: Hendzel
authors.forename: Philippe T
authors.initials: PT
authors.lastname: Georgel
authors.forename: Juan
authors.initials: J
authors.lastname: Ausió
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism* / Q000648:ultrastructure; D004247:DNA / Q000378:metabolism; D019175:DNA Methylation; D003851:Deoxyribonucleases; D006367:HeLa Cells; D006657:Histones / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D051783:Methyl-CpG-Binding Protein 2 / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure; D009707:Nucleosomes / Q000378:metabolism*; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D051381:Rats
chemical_list: D002843:Chromatin; D006657:Histones; D051783:Methyl-CpG-Binding Protein 2; D009707:Nucleosomes; D004247:DNA; D003851:Deoxyribonucleases