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. 2011 Jul 15;6(7):e22088. doi: 10.1371/journal.pone.0022088

Figure 7. Involvement of SIRT1 in regulating the expression of S-phase specific histone genes.

Figure 7

(A) H2B expression pattern of HeLa cells released from HU treatment. HeLa cells were synchronized at G1/S border with HU and then released into S phase. Cells were harvested at 2 hour interval and were analyzed with FACS and RT-PCR. 0 hour, G1/S border; 2 hours, early S-phase; 4 and 6 hours, mid-S-phase; 8 and 10 hours, late S-phase; 12 hours, S/G2 border; 16 hour, G2/M phase. (B) Enhanced H2B expression by HDAC inhibitors. HeLa cells synchronized at G1/S transition with HU were released and concomitantly treated with 2 µM TSA or 40 mM NAM for 2 hours. H2B mRNA level at 2 hours post release was set as 1, n = 4. (C) Increased H2B promoter activity as a result of inhibiting SIRT1. n = 3. (D) The efficacy of SIRT1 knockdown. Western-Blot was used to determine the SIRT1 protein level. The level of Sti1 serves as a control. (E) Up-regulated H2B and H4 expression in SIRT1 knockdown cells, n = 3. (F) Repressed H2B expression upon SIRT1 activation. HeLa cells were transfected with SIRT1 specific siRNA for 45 hours and then treated with 20 µM of resveratrol for additional 3 hours, n = 3. RSV, resveratrol, was dissolved in ethanol. Comparison between RSV treated groups with or without siSIRT1 transfection was analyzed with unpaired t test.