Does poly(ADP-ribosyl)ation regulate the DNA methylation pattern?

The correlations between poly(ADP-ribosyl)ated isoform of histone and the DNA methylation were investigated in vivo and in vitro through fluorescence-activated cell sorter analysis using L929 mouse fibroblasts. Results have shown that poly(ADP-ribosyl)ated H1 histone interacted with DNA during replication, inhibiting the de novo enzymic DNA methylation. The long and branched polymers as well as the poly(ADP-ribosyl)ated histones render protection to the CpG-rich DNA from being catalyzed by methyltransferases.