Imprinting centers (IC) can be defined as cis-elements that are recognized in the germ line and are epigenetically modified to bring about the full imprinting program in a somatic cell. Two paternally expressed human genes, HYMAI and PLAGL1 (LOT1/ZAC), are located within human chromosome 6q24. Within this region lies a 1-kb CpG island that is differentially methylated in somatic cells, unmethylated in sperm, and methylated in mature oocytes in mice, characteristic features of an IC. Loss of methylation of the homologous region in humans is observed in patients with transient neonatal diabetes mellitus and hypermethylation is associated with a variety of cancers, suggesting that this region regulates the expression of one or more key genes in this region involved in these diseases. We now report that a transgene carrying the human HYMAI/PLAGL1 DMR was methylated in the correct parent-origin-specific manner in mice and this was sufficient to confer imprinted expression from the transgene. Therefore, we propose that this DMR functions as the IC for the HYMAI/PLAGL1 domain.
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