title: Involvement of SUMO modification in MBD1- and MCAF1-mediated heterochromatin formation.
abstract: Small ubiquitin-related modifiers, SUMO-2/3 and SUMO-1, are involved in gene regulation and nuclear structures. However, little is known about the roles of SUMO, in heterochromatin formation of mammalian cells. Here we demonstrate that SUMOs directly interact with human MCAF1, which forms complexes with either the methyl-CpG-binding protein MBD1 or SETDB1, which trimethylates histone H3 at lysine 9 (H3-K9) in the presence of MCAF1. Modification of MBD1 with either SUMO-2/3 or SUMO-1 facilitated the interaction between MBD1 and MCAF1, suggesting that SUMOylation links the methylation of DNA and histones. In a cultured human cell line, SUMOs were localized in MBD1- and MCAF1-containing heterochromatin regions that were enriched in trimethyl-H3-K9 and the heterochromatin proteins HP1beta and HP1gamma. Specific knockdown of either SUMO-2/3 or SUMO-1 induced dissociation of MCAF1, trimethyl-H3-K9, and the HP1 proteins from the MBD1-containing heterochromatin foci, suggesting a requirement for SUMOs for heterochromatin assembly. These findings provide insights into the roles of SUMOylation in the regulation of heterochromatin formation and gene silencing.
authors.affiliation: Department of Regeneration Medicine, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto 860-0811, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Uchimura
authors.forename: Takaya
authors.initials: T
authors.lastname: Ichimura
authors.forename: Junsuke
authors.initials: J
authors.lastname: Uwada
authors.forename: Taro
authors.initials: T
authors.lastname: Tachibana
authors.forename: Satoko
authors.initials: S
authors.lastname: Sugahara
authors.forename: Mitsuyoshi
authors.initials: M
authors.lastname: Nakao
authors.forename: Hisato
authors.initials: H
authors.lastname: Saitoh
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D000090266:Chromobox Protein Homolog 5; D018899:CpG Islands; D004268:DNA-Binding Proteins / Q000378:metabolism*; D044127:Epigenesis, Genetic; D006367:HeLa Cells; D006570:Heterochromatin / Q000737:chemistry*; D006801:Humans; D009154:Mutation; D011485:Protein Binding; D051381:Rats; D012097:Repressor Proteins; D025842:SUMO-1 Protein / Q000737:chemistry / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: C501309:ATF7IP protein, human; C000715593:CBX1 protein, human; D004268:DNA-Binding Proteins; D006570:Heterochromatin; C066141:MBD1 protein, human; D012097:Repressor Proteins; D025842:SUMO-1 Protein; D014157:Transcription Factors; D000090266:Chromobox Protein Homolog 5