title: Characterization of a novel chromodomain-containing gene from the silkworm, Bombyx mori.
abstract: Heterochromatin protein 1 (HP1) is an evolutionarily conserved protein across different eukaryotic species, and is crucial in the establishment and maintenance of heterochromatin. HP1 proteins have two distinct functional domains, an N-terminal chromodomain (CD) and a C-terminal chromoshadow domain (CSD), which are required for the selective binding of HP1 proteins to modified histones. During our screen for HP1-like proteins in the Bombyx mori genome, we found a novel silkworm gene, Bombyx mori chromodomain protein 1 (BmCdp1), encoding a putative chromobox protein with only two CDs. The BmCdp1 family proteins are closely related to the HP1 proteins, and most of them belong to insect lineages. qRT-PCR analysis indicated that BmCdp1 mRNA was most abundantly expressed in early embryos, and relatively higher expression was observed in larval testes, hemocytes, and pupal ovaries. Western blot and immunostaining experiments showed that BmCdp1 was localized mainly in the nucleus of BmN4 cells. We searched BmCdp1-bound loci in the Bombyx genome by ChIP-seq analysis using Flag-tagged BmCdp1-expressing BmN4 cells. Combined with ChIP-qPCR experiments, we identified two reliable BmCdp1-bound loci in the genome. siRNA-mediated knockdown of BmCdp1 in BmN4 cells and early embryos did not affect the expression of the gene located close to the BmCdp1-bound locus.
authors.affiliation: Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Shoji
authors.forename: Takashi
authors.initials: T
authors.lastname: Kiuchi
authors.forename: Kahori
authors.initials: K
authors.lastname: Hara
authors.forename: Munetaka
authors.initials: M
authors.lastname: Kawamoto
authors.forename: Shinpei
authors.initials: S
authors.lastname: Kawaoka
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Arimura
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Tsutsumi
authors.forename: Sumio
authors.initials: S
authors.lastname: Sugano
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Toru
authors.initials: T
authors.lastname: Shimada
authors.forename: Susumu
authors.initials: S
authors.lastname: Katsuma
mesh_terms: D000818:Animals; D015153:Blotting, Western; D012831:Bombyx / Q000235:genetics*; D002460:Cell Line; D047369:Chromatin Immunoprecipitation; D020869:Gene Expression Profiling; D017344:Genes, Insect; D010802:Phylogeny; D034622:RNA Interference
keywords: Bombyx mori; CD; CSD; ChIP; Chromodomain; Chromoshadow domain; EST; HP1; Heterochromatin; chromatin immunoprecipitation; chromo domain; chromo shadow domain; expressed sequence tag; heterochromatin protein 1