Frequency of retroelements in methylation-prone and methylation-resistant genes identified in mouse cancer models and old mice. (A) Depletion of SINE and LTR but not LINE repeats near TSS marks methylated promoter CpG islands in a mouse model of myelodysplastic syndrome (MDS). Bone marrow samples of three NUP98-HOXD13 transgene animals that developed MDS (Lin et al. 2005) were studied by MCAM. Bone marrow samples from nontransgene animal of the same mouse strain was used as control, and the methylation status of approximately 6000 CpG island promoter genes was determined in the MCAM experiments. (B,C) The same pattern of retroelements depletion is observed in hypermethylated genes in CLL (Chen et al. 2009) and intestinal cancer mouse models (Hahn et al. 2008). (D) Depletion of SINE, LINE, and LTR repeats near TSS also marks age-related methylation promoter CpG islands. Small intestine tissue harvested from young (3-mo-old) and old (35-mo-old) C57BL/6J mice were used in MCAM experiments to identify age-related methylation.
