Fig. 3

Lack of cytosine methylation at full-length L1 insertions in cultured cancer cells. Top: Schematic of a full-length de novo human L1.3 insertion (in chr. 14 in derivative cell clone 7H2 after transfection of the HCT116 parental cell line, as previously mapped [13]). Black bars: PCR amplicons analyzed by bisulfite sequencing. Minimal de novo cytosine methylation was observed at the newly retrotransposed (1) 5' transduced sequence from the distal CMV promoter and proximal L1 5' UTR; and (2) in the spliced Neo reporter gene. PCR amplicons were generated using primers DES512 x DES530 (1); and DES515 x DES524 (2), respectively. Similar results were obtained at a second independent full-length L1 integrant on chromosome 3 in the 2A2 subclone of transfected HCT116 cells [13]