title: Functional domain analysis of human HP1 isoforms in Drosophila.
abstract: Three subtypes of HP1, a conserved non-histone chromosomal protein enriched in heterochromatin, have been identified in humans, HP1alpha, beta and gamma. In the present study, we utilized a Drosophila system to characterize human HP1 functions. Over-expression of HP1beta in eye imaginal discs caused abnormally patterned eyes, with reduced numbers of ommatidia, and over-expression of HP1gamma in wing imaginal discs caused abnormal wings, in which L4 veins were gapped. These phenotypes were specific to the HP1 subtypes and appear to reflect suppressed gene expression. To determine the molecular domains of HP1 required for each specific phenotype, we constructed a series of chimeric molecules with HP1beta and HP1gamma. Our data show that the C-terminal chromo shadow domain (CSD) of HP1gamma is necessary for HP1gamma-type phenotype, whereas for the HP1beta-type phenotype both the chromo domain and the CSD are required. These results suggest human HP1 subtypes use different domains to suppress gene expression in Drosophila cells.
authors.affiliation: Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Kato
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Kato
authors.forename: Miki
authors.initials: M
authors.lastname: Nishida
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Hayakawa
authors.forename: Tokuko
authors.initials: T
authors.lastname: Haraguchi
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Hiraoka
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: H Inoue
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Yamaguchi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D000090266:Chromobox Protein Homolog 5; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002875:Chromosomes / Q000378:metabolism; D004330:Drosophila / Q000235:genetics*; D006570:Heterochromatin / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
chemical_list: C000715593:CBX1 protein, human; C000715594:CBX5 protein, human; D002868:Chromosomal Proteins, Non-Histone; D006570:Heterochromatin; D020033:Protein Isoforms; D000090266:Chromobox Protein Homolog 5