Figure 5.

Restoration of H3K56 acetylation is necessary for recovery from UV-induced cell-cycle checkpoint arrest. (A) ASF1A-deficient cells exhibit cell-cycle checkpoint recovery defect. OSU-2 cells were arrested in G1 phase of the cell-cycle by serum starvation for 48 h. The arrested cells were transfected with ASF1A shRNA and after 24 h irradiated with 5 J m⁻² UV and released into the cell-cycle by addition of media containing serum. Transfection with ASF1A shRNA was performed again to maintain the knockdown up to 50 h. Cells were harvested at the indicated times, fixed with 70% ethanol and the DNA content determined by FACS. (B) H3K56R mutant cells are defective in recovery from UV-induced cell-cycle checkpoint arrest. H1299-H3.1 and H1299-H3K56R cells were synchronized by serum starvation for 24 h. Cells were then irradiated with 10 J m⁻² UV and released into the cell-cycle by addition of media containing serum. Cells were harvested at the indicated time points, fixed and DNA content determined by FACS.