title: pc1 and psc1, zebrafish homologs of Drosophila Polycomb and Posterior sex combs, encode nuclear proteins capable of complex interactions.
abstract: Drosophila Polycomb group proteins are thought to form multimeric nuclear complexes that are responsible for stable transmission of repressed states of gene expression during the proliferation of differentiating embryos. In this study, we cloned, sequenced, and characterized two Polycomb group homologs, designated pc1 and psc1, in zebrafish. Amino acid sequence analyses determined that pc1 is a structural homolog of Drosophila Polycomb and that psc1 is a homolog of Drosophila Posterior sex combs. Northern blots and whole-mount in situ hybridization revealed that pc1 and psc1 had overlapping expression patterns at successive stages of embryogenesis. Immunocytochemistry localized both Pc1 and Psc1 protein in blastomere nuclei. Pull-down assays and two-hybrid system deletion analyses showed that these proteins were capable of homotypic and heterotypic interactions and identified the regions required for these interactions. The evidence supports the idea that zebrafish Polycomb group proteins, like those of other species, form nuclear complexes with compositions that may vary in a spatio-temporal manner during development.
authors.affiliation: Department of Biology, School of Education, Waseda University, 1-6-1 Nishi-Waseda, Shinjuku, Tokyo 169-8050, Japan.
authors.forename: Akinori
authors.initials: A
authors.lastname: Kawamura
authors.forename: Shin'ichiro
authors.initials: S
authors.lastname: Yokota
authors.forename: Kouji
authors.initials: K
authors.lastname: Yamada
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Inoue
authors.forename: Keiji
authors.initials: K
authors.lastname: Inohaya
authors.forename: Ken
authors.initials: K
authors.lastname: Yamazaki
authors.forename: Ikuo
authors.initials: I
authors.lastname: Yasumasu
authors.forename: Toru
authors.initials: T
authors.lastname: Higashinakagawa
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000502:physiology; D001757:Blastomeres / Q000166:cytology / Q000378:metabolism; D015152:Blotting, Northern; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins; D004330:Drosophila; D029721:Drosophila Proteins; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism; D017403:In Situ Hybridization; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism*; D063150:Polycomb Repressive Complex 1; D011485:Protein Binding / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis; D020798:Two-Hybrid System Techniques; D015027:Zebrafish / Q000196:embryology; D029961:Zebrafish Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D019476:Insect Proteins; D009687:Nuclear Proteins; C066770:Pc protein, Drosophila; D012333:RNA, Messenger; D029961:Zebrafish Proteins; C459595:bmi1a protein, zebrafish; C459594:cbx2 protein, zebrafish; C071050:Psc protein, Drosophila; D063150:Polycomb Repressive Complex 1