The histone methylation link

In fact, the cross-talk between histone methylation and DNA methylation has been experimentally demonstrated for the first time in Neurospora [145] (see commentary by Bird [146]) and proved the second scenario. Using the power of Neurospora genetics, Tamaru and Selker [145] have identified a gene which, when mutated, abolishes methylation of all tested DNA sequences. This gene, dim-5, is different from dim-2, the previously identified gene that encodes the only DNA methyltransferase in Neurospora responsible for all known cytosine methylation in this fungus. The dim-5 gene encodes a histone H3 methyltransferase the deduced polypeptide sequence contains a SET domain with sequence similarity to some known histone methyltransferases moreover, the recombinant DIM-5 protein exhibits histone methyltransferase activity in vitro. Additional in vivo experiments 

Santoro and Grummt, using as experimental model the nucleolar remodeling complex NoRC and rDNA transcription in mammalian cells, have shown that 

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