Comparative Genomic Sequencing Identifies Novel Tissue-Specific Enhancers and Sequence Elements for Methylation-Sensitive Factors Implicated in Igf2/H19 Imprinting

AUTOR(ES)

Ishihara, Ko

FONTE

Cold Spring Harbor Laboratory Press

RESUMO

A differentially methylated region (DMR) and endoderm-specific enhancers, located upstream and downstream of the mouse H19 gene, respectively, are known to be essential for the reciprocal imprinting of Igf2 and H19. To explain the same imprinting patterns in non-endodermal tissues, additional enhancers have been hypothesized. We determined and compared the sequences of human and mouse H19 over 40 kb and identified 10 evolutionarily conserved downstream segments, 2 of which were coincident with the known enhancers. Reporter assays in transgenic mice showed that 5 of the other 8 segments functioned as enhancers in specific mesodermal and/or ectodermal tissues. We also identified a conserved 39-bp element that appeared repeatedly within the DMR and formed complexes with specific nuclear factors. Binding of one of the factors was inhibited when the target sequence contained methylated CpGs. These complexes may contribute to the presumed boundary function of the unmethylated DMR, which is proposed to insulate maternal Igf2 from the enhancers. Our results demonstrate that comparative genomic sequencing is highly efficient in identifying regulatory elements.

Documentos Relacionados

• Role of CTCF Binding Sites in the Igf2/H19 Imprinting Control Region†
• Epigenetic changes encompassing the IGF2/H19 locus associated with relaxation of IGF2 imprinting and silencing of H19 in Wilms tumor.
• Novel Imprinted DLK1/GTL2 Domain on Human Chromosome 14 Contains Motifs that Mimic Those Implicated in IGF2/H19 Regulation
• Rapid quantitation of methylation differences at specific sites using methylation-sensitive single nucleotide primer extension (Ms-SNuPE).
• A new imprinted gene cloned by a methylation-sensitive genome scanning method.