title: The Influence of Polyploidy and Genome Composition on Genomic Imprinting in Mice.
abstract: Genomic imprinting is an epigenetic mechanism that switches the expression of imprinted genes involved in normal embryonic growth and development in a parent-of-origin-specific manner. Changes in DNA methylation statuses from polyploidization are a well characterized epigenetic modification in plants. However, how changes in ploidy affect both imprinted gene expression and methylation status in mammals remains unclear. To address this, we used quantitative real time PCR to analyze expression levels of imprinted genes in mouse tetraploid fetuses. We used bisulfite sequencing to assess the methylation statuses of differentially methylated regions (DMRs) that regulate imprinted gene expression in triploid and tetraploid fetuses. The nine imprinted genes H19, Gtl2, Dlk1, Igf2r, Grb10, Zim1, Peg3, Ndn, and Ipw were all unregulated; in particular, the expression of Zim1 was more than 10-fold higher, and the expression of Ipw was repressed in tetraploid fetuses. The methylation statuses of four DMRs H19, intergenic (IG), Igf2r, and Snrpn in tetraploid and triploid fetuses were similar to those in diploid fetuses. We also performed allele-specific RT-PCR sequencing to determine the alleles expressing the three imprinted genes Igf2, Gtl2, and Dlk1 in tetraploid fetuses. These three imprinted genes showed monoallelic expression in a parent-of-origin-specific manner. Expression of non-imprinted genes regulating neural cell development significantly decreased in tetraploid fetuses, which might have been associated with unregulated imprinted gene expression. This study provides the first detailed analysis of genomic imprinting in tetraploid fetuses, suggesting that imprinted gene expression is disrupted, but DNA methylation statuses of DMRs are stable following changes in ploidy in mammals.
authors.affiliation: From the Laboratory of Animal Genetics and Reproduction, Research Faculty of Agriculture, Hokkaido University, Kita-9, Nishi-9, Kita-ku, Sapporo 060-8589 and.
authors.forename: Wataru
authors.initials: W
authors.lastname: Yamazaki
authors.affiliation: the Laboratory of Animal Genetics, Department of Sustainable Agriculture, College of Agriculture, Food and Environmental Science, Rakuno Gakuen University, Bunkyodai-Midorimachi, Ebetsu, Hokkaido 069-8501, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Amano
authors.affiliation: From the Laboratory of Animal Genetics and Reproduction, Research Faculty of Agriculture, Hokkaido University, Kita-9, Nishi-9, Kita-ku, Sapporo 060-8589 and.
authors.forename: Hanako
authors.initials: H
authors.lastname: Bai
authors.affiliation: From the Laboratory of Animal Genetics and Reproduction, Research Faculty of Agriculture, Hokkaido University, Kita-9, Nishi-9, Kita-ku, Sapporo 060-8589 and.
authors.forename: Masashi
authors.initials: M
authors.lastname: Takahashi
authors.affiliation: From the Laboratory of Animal Genetics and Reproduction, Research Faculty of Agriculture, Hokkaido University, Kita-9, Nishi-9, Kita-ku, Sapporo 060-8589 and k-hara@anim.agr.hokudai.ac.jp.
authors.forename: Manabu
authors.initials: M
authors.lastname: Kawahara
mesh_terms: D000818:Animals; D019175:DNA Methylation; D005260:Female; D005333:Fetus / Q000196:embryology*; D018507:Gene Expression Regulation, Developmental; D016678:Genome; D018392:Genomic Imprinting; D008297:Male; D051379:Mice; D011123:Polyploidy
keywords: DNA methylation; epigenetics; gene expression; mammal; mouse