Transcriptional gene silencing enables multi-cellular eukaryotes to achieve differential gene expression during differentiation. In plants and mammals, silent chromatin is associated with hypermethylation of DNA at CpG sites and methylation of histone H3 at lysine 9 (H3K9-met). These covalent modifications attract specific chromatin binding factors and ensure faithful inheritance of gene expression patterns during DNA replication and mitosis, referred as epigenetic inheritance. Importantly, chromatin factors which act independent of DNA methylation in maintenance of heritable gene silencing...