te, and “1446712 is associated with a distinct transcriptional outcome. These diverse methylated residues are bound by multiple “reader”proteins, which in turn interact with transcriptional activators or get Nigericin (sodium salt) repressors. H3K4me2/3, H3K36me1/ 3, H3K79me1/2 and H4K20me1 are associated with transcriptional activation, while H3K9me2/3, H3K27me2/3, H3K79me3 and H4K20me3 are associated with transcriptional repression. With the recent discovery of histone demethylases, modification of histone lysine residues is now viewed as “9353416 a more dynamic process than previously thought. Multiple studies have shown that histonemodifying enzymes target specific genes, some of which participate in specific biological processes and pathways. It is still under debate whether targets of a histone-modifying enzyme achieve regulation as a single module, allowing coordinated change in expression in various biological processes, including diseased conditions, or represent a mix of differentially expressed genes. Histone demethylases are represented by a few flavin-dependent amine oxidases and a-ketoglutarate-Fe-dependent dioxygenases that are included in a large superfamily of the JmjC domain proteins. Histone methylation is also accomplished by multiple enzymes, and in most cases involves a catalytic SET domain related to yeast Set1 and Drosophila Trithorax. The same modification can be executed by several enzymes, which in most cases are members of the same protein family, suggesting their functional specialization through differential expression patterns. Histone demethylases removing the methyl groups from histone H3K4 are 
encoded by two autosomal genes, KDM5A/ JARID1A/RBP2 and KDM5B/JARID1B/PLU1, and two genes located on the sex chromosomes, KDM5C and KDM5D, and increasing evidence supports individual and nonredundant roles within this family. Therefore, it is conceivable that the overall epigenetic landscape is dependent on the spatial and temporal distribution of corresponding HDM and HMT enzymes. KDM5A is directly bound to H3K4me3 in vivo. Despite the repressive demethylase activity associated with KDM5A function in demethylation at histone H3K4, it plays a role in both transcriptional repression and activation. KDM5A contains not only an enzymatic domain but also a highly specific H3K4me3 reader domain, which without doubt could affect other modifications nearby either cooperatively or antagonistically. Consistent with these observations, our ChIP-on-chip analysis showed that KDM5A binding to genomic loci highly correlates with transcriptionally active promoters containing H3K4me3 and other modifications associated with transcriptional activation, such as H3K36me3, H3K79me2 and acetylation at H3K9 and K14, August 2011 | Volume 6 | Issue 8 | e24023 Co-Regulation of Histone-Modifying Enzymes but not H3K27me3. Considering the diverse functions identified for families of enzymes like KDM5, it will be of particular interest to understand their contribution to histone H3K4 methylation in promoter- and cell type-dependent manner. Genomic analyses in Drosophila and mammals showed that Trithorax group genes antagonize regulation by Polycomb group genes to create a repertoire of alternative states of gene expression. Accumulating evidence has shown that recruitment of HMTs or HDMs of opposing activity to the same genomic regions underlies important developmental decisions. In particular, the HMTs MLL1 and EZH2 are components of the Trithorax and Polycomb complexes, respectively, tha