Matrix-attachment regions in the mouse chromosome 7F imprinted domain.

We have mapped the matrix-attachment regions (MARs) in 200 kilobases of the mouse Chromosome (Chr) 7F imprinted domain. MARs are genetic elements known to have effects in cis on methylation at nonimprinted loci. The imprinting of the Igf2 and Ins2 genes is dependent on the transcription of the downstream H19 gene. The transcription of H19 is dependent in turn on its methylation status. The cis-acting regulators of methylation at this site are not known. As MARs are potential regulators not only of methylation but also other elements of genomic imprinting, we mapped the MARs within the 200 kilobases around H19. This report describes the mapping of four MARs from this region.