Effect of modified H2A.Z protein to gene expression in DT40 cells.

H2A.Z-nucleosomes participate in both euchromatin and heterochromatin and it has proven difficult to reveal how the disparate roles and stability features imparted by H2A.Z are connected. Using an in situ assay of nucleosome stability in nuclei of DT40 cells expressing engineered forms of the variant we show that H2A.Z is released from nucleosomes of peripheral heterochromatin at unusually high salt concentrations, compared to cells expressing C-terminally truncated H2A.Z. Binding of the tail-peptide (C9) to reconstituted nucleosomes, DNA and the nuclear lamina were detected. Upon treatment of HeLa nuclei with C9, the H2A.Z-nucleosomes assumed canonical stability, the peripheral heterochromatin became dispersed and overall nuclease sensitivity increased, recapitulating tail-dependent differences in DT40. When introduced into live cells, C9 elicited chromatin reorganization and transcriptional down-regulation of ~600 genes. Thus, large-scale epigenetic modulation can be achieved by targeting or making advantage of molecular interactions involving the C-terminal tail of H2A.Z. Gene expression profile in DT40 cell line was measured in Wild Type, double knock-out (DKO) +DKO H2A.Z1 or DKO +H2A.Z1ΔC mutant H2A.Z protein containing cell lines. One experiment was performed per sample.