title: Enhanced self-renewal of hematopoietic stem cells mediated by the polycomb gene product Bmi-1.
abstract: The Polycomb group (PcG) gene Bmi-1 has recently been implicated in the maintenance of hematopoietic stem cells (HSC) from loss-of-function analysis. Here, we demonstrate that increased expression of Bmi-1 promotes HSC self-renewal. Forced expression of Bmi-1 enhanced symmetrical cell division of HSCs and mediated a higher probability of inheritance of stemness through cell division. Correspondingly, forced expression of Bmi-1, but not the other PcG genes, led to a striking ex vivo expansion of multipotential progenitors and marked augmentation of HSC repopulating capacity in vivo. Loss-of-function analyses revealed that among PcG genes, absence of Bmi-1 is preferentially linked with a profound defect in HSC self-renewal. Our findings define Bmi-1 as a central player in HSC self-renewal and demonstrate that Bmi-1 is a target for therapeutic manipulation of HSCs.
authors.affiliation: Laboratory of Stem Cell Therapy, Center for Experimental Medicine, The Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan. aiwama@ims.u-tokyo.ac.jp
authors.forename: Atsushi
authors.initials: A
authors.lastname: Iwama
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Oguro
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Negishi
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kato
authors.forename: Youhei
authors.initials: Y
authors.lastname: Morita
authors.forename: Hiroko
authors.initials: H
authors.lastname: Tsukui
authors.forename: Hideo
authors.initials: H
authors.lastname: Ema
authors.forename: Takehiko
authors.initials: T
authors.lastname: Kamijo
authors.forename: Yuko
authors.initials: Y
authors.lastname: Katoh-Fukui
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Koseki
authors.forename: Maarten
authors.initials: M
authors.lastname: van Lohuizen
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Nakauchi
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D017353:Gene Deletion; D005786:Gene Expression Regulation; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009687:Nuclear Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D063150:Polycomb Repressive Complex 1; D063146:Polycomb-Group Proteins; D011518:Proto-Oncogene Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C489421:Bmi1 protein, mouse; D009687:Nuclear Proteins; D063146:Polycomb-Group Proteins; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; D063150:Polycomb Repressive Complex 1