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.

Reciprocal Changes of H3K27Ac and H3K27me3 at the Promoter Regions of the Critical Genes for Endometrial Decidualization

“…Genomic DNA and total RNA were isolated from cells using AllPrep DNA/RNA Kit (Qiagen, Tokyo, Japan). Quantitative RT-PCR was performed as described previously [22] using the following PCR primers: 5 -AAGCTGTAGAGATTGAGGAGCAAAC-3 and 5 -AAGCTGTAGAGATTGAGGAGCAAAC-3 for PRL, 5 -CGAAGGCTCTCCATGTCACCA-3 and 5 -TGTCTCCTGTGCCTTGGCTAAAC-3 for IGFBP1, and 5 -GCGGAAGGGTACAGCCAAT-3 and 5 -GCAGCCGGCGCAAA -3 for L19.…”

Identification of G-quadruplex structures that possess transcriptional regulating functions in the Dele and Cdc6 CpG islands

“…Our results indicate that the Dele CGI contains a promoter for 1700086O06Rik , an insulator, and a promoter for Dele (that also possesses enhancer activity). The insulator sequence may have a blocking activity that prevents promoter-enhancer interaction [ 37 ]; therefore, the enhancer activity of the Dele G4 for 1700086O06Rik promoter has not been detected.…”

High expression of NFX1‐123 in HPV positive head and neck squamous cell carcinomas

“…17,21 Although its protein expression only moderately increased in HPV+ HNSCC cell lines (Figure 4(D)), and mRNA expression was not determined, its role in cells is important. CCNB1IP1 is an E3 ubiquitin ligase that functions in cell cycle progression 43,44 ; the maintenance of cell cycle progression during HPV cancer oncogenesis is fundamental, and it is known that this is co-opted by HR HPV oncogenes E6 and E7.…”