A METHYLATION IMPRINT MARK IN THE MOUSE IMPRINTED GENE GRF1 CDC25MM LOCUS SHARES A COMMON FEATURE WITH THE U2AFBP-RS GENE - AN ASSOCIATION WITH A SHORT TANDEM REPEAT AND A HYPERMETHYLATED REGION/

We identified a sperm-specific methylation imprint mark (Site II) asso ciated with a short, tandem repeat sequence and a site/region methylat ed in both gamates (Site I) in the Grf1 locus on mouse chromosome 9, w hich shared a common feature with the U2afbp-rs gene. Sites or regions of gamete-specific methylation in imprinted genes are strong candidat es for carrying information regarding the parental origin of alleles. The gamete-specific methylation pattern of Sites I and II was conserve d after fertilization, but attained the somatic cell pattern by the bl astocyst stage. In primordial germ cells, Site I was methylated, but S ite II was unmethylated in both male and female embryos, suggesting th at the sperm-specific methylation imprint mark in Site II was establis hed during spermatogenesis. These common features in methylation impri nt regions may be a clue to identifying regions carrying primary infor mation for the imprinting regulation. (C) 1998 Academic Press.