title: Bmi1 cooperates with Dnmt1-associated protein 1 in gene silencing.
abstract: Polycomb group (PcG) proteins are involved in gene silencing through chromatin modifications. Among polycomb repressive complexes (PRCs), PRC1 exhibits H2A-K119 ubiquitin E3 ligase activity. However, the molecular mechanisms underlying PRC1-mediated gene silencing remain largely obscure. In this study, we found that Bmi1 directly interacts with Dnmt-associated protein 1 (Dmap1), which has been characterized to associate with the maintenance DNA methyltransferase, Dnmt1. Bmi1 was demonstrated to form a ternary complex with Dmap1 and Dnmt1 with Dmap1 in the central position. Chromatin immunoprecipitations confirmed the ternary complex formation within the context of the PRC1 at the Bmi1 target loci. Loss of Dmap1 binding to the Bmi1 target loci was tightly associated with derepressed gene expression in Bmi1-/- cells. Dmap1 knockdown exhibited the same impact as Bmi1 knockout did on the expression of Bmi1 targets, including Hox genes. Collectively, our findings suggest that Bmi1 incorporates Dmap1 in polycomb gene silencing.
authors.affiliation: Department of Cellular and Molecular Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Negishi
authors.forename: Atsunori
authors.initials: A
authors.lastname: Saraya
authors.forename: Satoru
authors.initials: S
authors.lastname: Miyagi
authors.forename: Kenji
authors.initials: K
authors.lastname: Nagao
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Inagaki
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Nishikawa
authors.forename: Shoji
authors.initials: S
authors.lastname: Tajima
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Koseki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tsuda
authors.forename: Yoshinari
authors.initials: Y
authors.lastname: Takasaki
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Nakauchi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Iwama
mesh_terms: D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D002522:Chlorocebus aethiops; D047369:Chromatin Immunoprecipitation; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation; D015870:Gene Expression; D020868:Gene Silencing; D006412:Hematopoietic Stem Cells / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics; D051379:Mice; D018345:Mice, Knockout; D041681:NIH 3T3 Cells; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D063150:Polycomb Repressive Complex 1; D063146:Polycomb-Group Proteins; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020798:Two-Hybrid System Techniques
chemical_list: C489421:Bmi1 protein, mouse; C485852:Dmap1 protein, mouse; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; D063146:Polycomb-Group Proteins; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; D063150:Polycomb Repressive Complex 1