title: Cell differentiation induces TIF1beta association with centromeric heterochromatin via an HP1 interaction.
abstract: The transcriptional intermediary factor 1 (TIF1) family protein TIF1beta is a corepressor for Krüppel-associated box (KRAB)-domain-containing zinc finger proteins and plays a critical role in early embryogenesis. Here, we examined TIF1beta distribution in the nucleus of mouse embryonic carcinoma F9 cells during retinoic-acid-induced primitive endodermal differentiation. Using confocal immunofluorescence microscopy, we show that, although TIF1beta is diffusely distributed throughout the nucleoplasm of undifferentiated cells, it relocates and concentrates into distinct foci of centromeric heterochromatin in differentiated cells characterized by a low proliferation rate and a well developed cytokeratin network. This relocation was not observed in isoleucine-deprived cells, which are growth arrested, or in compound RXR alpha(-/-)/RAR gamma(-/-) null mutant cells, which are resistant to RA-induced differentiation. Amino-acid substitutions in the PxVxL motif of TIF1beta, which abolish interaction with members of the heterochromatin protein 1 (HP1) family, prevent its centromeric localization in differentiated cells. Collectively, these data provide compelling evidence for a dynamic nuclear compartmentalization of TIF1beta that is regulated during cell differentiation through a mechanism that requires HP1 interaction.
authors.affiliation: Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP/Collège de France, BP163, 67404 Illkirch-Cedex, France.
authors.forename: Florence
authors.initials: F
authors.lastname: Cammas
authors.forename: Mustapha
authors.initials: M
authors.lastname: Oulad-Abdelghani
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Vonesch
authors.forename: Yolande
authors.initials: Y
authors.lastname: Huss-Garcia
authors.forename: Pierre
authors.initials: P
authors.lastname: Chambon
authors.forename: Régine
authors.initials: R
authors.lastname: Losson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002453:Cell Cycle / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology*; D002467:Cell Nucleus / Q000378:metabolism; D002503:Centromere / Q000378:metabolism*; D000090266:Chromobox Protein Homolog 5; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D006570:Heterochromatin / Q000378:metabolism*; D007532:Isoleucine / Q000378:metabolism; D051379:Mice; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors; D014212:Tretinoin / Q000378:metabolism; D000076183:Tripartite Motif-Containing Protein 28; D014407:Tumor Cells, Cultured
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D006570:Heterochromatin; D009687:Nuclear Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D007532:Isoleucine; D000090266:Chromobox Protein Homolog 5; D014212:Tretinoin; C103190:Trim28 protein, mouse; D000076183:Tripartite Motif-Containing Protein 28