CpG island chromatin is shaped by recruitment of ZF-CxxC proteins

Most mammalian gene promoters are embedded within genomic regions called CpG islands, characterized by elevated levels of nonmethylated CpG dinucleotides. Here, we describe recent work demonstrating that CpG islands act as specific nucleation sites for the zinc finger CxxC domain-containing proteins CFP1 and KDM2A. Importantly, both CFP1 and KDM2A are associated with enzymatic activities that modulate specific histone lysine methylation marks. The action of these zinc finger CxxC domain proteins therefore imposes a defined chromatin architecture on CpG islands that distinguishes these important regulatory elements from the surrounding genome. The functional consequence of this CpG island-directed chromatin environment is discussed.