Dissociation of mammalian Polycomb-group proteins, Ring1B and Rae28/Ph1, from the chromatin correlates with configuration changes of the chromatin in mitotic and meiotic prophase.
The Polycomb group (PcG) gene products form complexes that regulate chromatin configuration to mediate cellular memory to postmitotic somatic cells and postmeiotic oocytes in Drosophila melanogaster. Structural and functional similarities of PcG proteins between invertebrates and vertebrates suggest mammalian PcG proteins may be involved to imprint transcriptional status at various loci into postmitotic and postmeiotic daughter cells. To address molecular mechanisms underlying PcG-mediated cellular memory, it might be a prerequisite to understand subcellular localization of PcG proteins during mitosis and meiosis. In this study, we analyzed subcellular localization of Rae28/Ph1 and Ring1B by using newly generated monoclonal antibodies in mitotic somatic cells and meiotic mouse oocytes. Results suggest that Rae28/Ph1 and Ring1B dissociate from the chromatin upon its condensation in mitotic prophase in the U2-OS human osteosarcoma cell line. During maturation of oocytes, significant alterations of Rae28/Ph1 and Ring1B localization are concordant with configuration changes of the chromatin at the germinal vesicle stage of meiotic prophase. Importantly, dissociation of Rae28/Ph1 and Ring1B from the chromatin temporally correlates with transcriptional arrest both in mitosis and meiosis. Present and previous observations suggest molecular mechanisms required for mitotic regulation of RNA polymerase II could be involved in dissociation of PcG proteins.
Miyagishima
Hiro
H
Department of Molecular Embryology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuoku, 260-8670 Chiba, Japan.
Isono
Kyoichi
K
Fujimura
Yuichi
Y
Iyo
Masaomi
M
Takihara
Yoshihiro
Y
Masumoto
Hiroshi
H
Vidal
Miguel
M
Koseki
Haruhiko
H
D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D015153:Blotting, Western; D002352:Carrier Proteins; D018797:Cell Cycle Proteins / Q000032:analysis / Q000378:metabolism; D045744:Cell Line, Tumor; D002843:Chromatin / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D029721:Drosophila Proteins / Q000032:analysis / Q000378:metabolism; D018398:Homeodomain Proteins / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008540:Meiosis; D051379:Mice; D008938:Mitosis; D009865:Oocytes / Q000737:chemistry; D063150:Polycomb Repressive Complex 1; D063146:Polycomb-Group Proteins; D011418:Prophase; D011485:Protein Binding; D012097:Repressor Proteins / Q000032:analysis* / Q000145:classification / Q000378:metabolism
D000911:Antibodies, Monoclonal; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D002843:Chromatin; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; C491239:PHC1 protein, human; C066770:Pc protein, Drosophila; C103827:Phc1 protein, mouse; D063146:Polycomb-Group Proteins; D012097:Repressor Proteins; D063150:Polycomb Repressive Complex 1