H19-icr - H19/Igf2 imprinting control region

This region represents a methylation-sensitive enhancer-blocking element that controls imprinted expression of the non-coding H19 gene and the gene encoding insulin-like growth factor 2 (Igf2). These neighboring genes exist in a head-to-tail arrangement in opposite orientations and share an enhancer region, but the H19 gene is only expressed from the maternal allele, while the Igf2 gene is only expressed from the paternal allele. This element, which is a differentially methylated region (DMR), is located just upstream of the H19 gene. It is unmethylated on the maternal allele, which permits binding of the CTCF protein, and it can thus function as an enhancer-blocking element to prevent activation of Igf2 by the enhancer, thereby allowing H19 activation. However, it is methylated on the paternal allele and CTCF cannot bind, thus allowing the enhancer to activate the IGF2 gene, and the H19 gene is silenced. This DMR includes two DNase I hypersensitive sites and four CTCF-binding sites. Oct4/Sox2-binding sites are involved in the maintenance of a hypomethylated state of this imprinting control region on the maternal allele. [provided by RefSeq, Aug 2015]

NCBI Orthologs

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