DNA-RNA-protein gang together in silence.

Two recent reports demonstrate interdependence between DNA and histone methylation in Arabidopsis. ddm1 (decrease in DNA methylation 1) mutants switch histone methylation from a form associated with inactive chromatin to a form connected to actively transcribed genomic regions. The loss of DNA methylation and shift in histone methylation cause transcriptional derepression of heterochromatic regions. In a related report, small RNAs in Schizosaccharomyces pombe mark histone methylation to form heterochromatin, suggesting that methylation systems work alongside RNA metabolism.