5-Aza-2'-deoxycytidine, approved by the FDA for the treatment of myelodysplastic 
syndrome (MDS), is incorporated into the DNA of dividing cells where it 
specifically inhibits DNA methylation by forming covalent complexes with the DNA 
methyltransferases (DNMTs). In an effort to study the correlations between DNA 
methylation, nucleosome remodeling, and gene reactivation, we investigate the 
integrated epigenetic events that worked coordinately to reprogram the 
methylated and closed promoters back to permissive chromatin configurations 
after 5-Aza-2'-deoxycytidine treatment. The ChIP results indicate that H2A.Z is 
deposited at promoter regions by the Snf2-related CBP activator protein (SRCAP) 
complex following DNA demethylation. According to our genome-wide expression and 
DNA methylation profiles, we find that the complete re-activation of silenced 
genes requires the insertion of the histone variant H2A.Z, which facilitates the 
acquisition of regions fully depleted of nucleosome as demonstrated by NOMe-seq 
(Nucleosome Occupancy Methylome-sequencing) assay. In contrast, SRCAP-mediated 
H2A.Z deposition is not required for maintaining the active status of 
constitutively expressed genes. By combining Hpa II digestion with NOMe-seq 
assay, we show that hemimethylated DNA, which is generated following drug 
incorporation, remains occupied by nucleosomes. Our data highlight H2A.Z as a 
novel and essential factor involved in 5-Aza-2'-deoxycytidine-induced gene 
reactivation. Furthermore, we elucidate that chromatin remodeling translates the 
demethylation ability of DNMT inhibitors to their downstream efficacies, 
suggesting future therapeutic implications for chromatin remodelers.