title: An insulator element located at the cyclin B1 interacting protein 1 gene locus is highly conserved among mammalian species.
abstract: Insulators are cis-elements that control the direction of enhancer and silencer activities (enhancer-blocking) and protect genes from silencing by heterochromatinization (barrier activity). Understanding insulators is critical to elucidate gene regulatory mechanisms at chromosomal domain levels. Here, we focused on a genomic region upstream of the mouse Ccnb1ip1 (cyclin B1 interacting protein 1) gene that was methylated in E9.5 embryos of the C57BL/6 strain, but unmethylated in those of the 129X1/SvJ and JF1/Ms strains. We hypothesized the existence of an insulator-type element that prevents the spread of DNA methylation within the 1.8 kbp segment, and actually identified a 242-bp and a 185-bp fragments that were located adjacent to each other and showed insulator and enhancer activities, respectively, in reporter assays. We designated these genomic regions as the Ccnb1ip1 insulator and the Ccnb1ip1 enhancer. The Ccnb1ip1 insulator showed enhancer-blocking activity in the luciferase assays and barrier activity in the colony formation assays. Further examination of the Ccnb1ip1 locus in other mammalian species revealed that the insulator and enhancer are highly conserved among a wide variety of species, and are located immediately upstream of the transcriptional start site of Ccnb1ip1. These newly identified cis-elements may be involved in transcriptional regulation of Ccnb1ip1, which is important in meiotic crossing-over and G2/M transition of the mitotic cell cycle.
authors.affiliation: Department of Maternal-Fetal Biology, National Research Institute for Child Health and Development, Setagaya, Tokyo, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Yoshida
authors.affiliation: Department of Maternal-Fetal Biology, National Research Institute for Child Health and Development, Setagaya, Tokyo, Japan.
authors.forename: Junko
authors.initials: J
authors.lastname: Tomikawa
authors.affiliation: Department of Human Genetics, National Research Institute for Child Health and Development, Setagaya, Tokyo, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Inaki
authors.affiliation: Department of Biological Sciences, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kimura
authors.affiliation: Department of Human Genetics, National Research Institute for Child Health and Development, Setagaya, Tokyo, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Onodera
authors.affiliation: Department of Maternal-Fetal Biology, National Research Institute for Child Health and Development, Setagaya, Tokyo, Japan.
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Hata
authors.affiliation: Department of Maternal-Fetal Biology, National Research Institute for Child Health and Development, Setagaya, Tokyo, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Nakabayashi
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D002478:Cells, Cultured; D019175:DNA Methylation; D005786:Gene Expression Regulation; D056426:Genetic Loci; D038101:Insulator Elements; D051379:Mice; D008810:Mice, Inbred C57BL; D044767:Ubiquitin-Protein Ligases
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; C473026:CCNB1IP1 protein, human; D044767:Ubiquitin-Protein Ligases