The Unmethylated State of CpG Islands in Mouse Fibroblasts Depends on the Poly(ADP-ribosyl)ation Process

摘要: Abstract In vivo and in vitroexperiments carried out on L929 mouse fibroblasts suggested that the poly(ADP-ribosyl) ation process acts somehow as a protecting agent against full methylation of CpG dinucleotides genomic DNA. Since islands, which are found almost exclusively at 5′-end housekeeping genes, rich dinucleotides, target mammalian DNA methyltransferase, we examined possibility poly(ADP-ribosyl)ation reaction is involved maintaining unmethylated state these sequences. Experiments were conducted by two different strategies, using either methylation-dependent restriction enzymes purified or sequence-dependent enzyme an aliquot same DNA, previously modified bisulfite reaction. With enzymes, it was observed “HpaII tiny fragments” greatly decreased when cells preincubated with 3-aminobenzamide, well known inhibitor poly(ADP-ribose) polymerase. The other experimental approach allowed us to prove that, consequence inhibition process, anomalous pattern could be evidenced island promoter fragment Htf9 gene, amplified from obtained 3-aminobenzamide. These data confirm hypothesis least for region, active protects island.