Figure 4. Focal Heterochromatin on the Silent Igf2r Promoter.
(A) ChIP-Chip profile of active and repressive epigenetic marks on the paternal (Pat) Igf2r imprinted cluster in MEFF cells. Details as in Figure 3. Only peaks reproducible in biological replicas (Figure S6) were considered positive.
(B) Chip-PCR of the Air and Igf2r promoters and the Au76-psg in cells carrying an Air ncRNA truncated from 108 to 3 kb on the paternal allele (Sleutels et al., 2002). This shows a loss of repressive H3K9me3 on Igf2r and Au76-psg when Air is truncated to 3 kb. H4K20me3 was also lost on these two elements (data not shown).