Characterization of gene expression and methylation patterns of the bovine IGF2 gene in gametes and preimplantation embryos of different origins

DNA methylation at cytosine molecules is one of the best known epigenetic mechanisms to date and involved in genomic imprinting. Imprinting is characterized by mono-allelic gene expression and plays a crucial role during early mammalian development. While insight into the epigenetic phenomenon of imprinting is mainly derived from mice and humans, information is scarce in cattle. This study reports the methylation status of the bovine Insulin-like growth factor2 gene (IGF2) in gametes and preimplantation embryos of different origins including cloned bovine embryos. Additionally, expression patterns of the bovine IGF2, Insulinlike growth factor2 receptor (IGF2R) and Mammalian achaete-scute homologue2 (Mash2) genes were characterized in bovine blastocysts. This is the first study of DNA methylation within the bovine IGF2 gene in preimplantation embryos and the first report about the identification of an intragenic Differentially Methylated Region (DMR) within a bovine imprinted gene.