Transgenic Epigenetics: Using Transgenic Organisms to Examine Epigenetic Phenomena

Figure 1

Imprinting at the Igf2 and H19 locus. On the maternally inherited allele, CTCF binds to the unmethylated ICR (red parallelogram) and the downstream enhancers (black circle) drive expression of H19. On the paternally inherited allele, the ICR is methylated (black lollipops), which prevents binding of the insulator protein CTCF, and enables the downstream enhancers to stimulate expression of Igf2. The maternal Igf2 gene exhibits repressive histone marks (black flags), while these marks are found on the paternal ICR and H19 gene.