Importantly, several known target genes of Roxadustat order FoxO3 changed expression during days 1 and 2 of liver regeneration (Bcl6, cyclin D1, cyclin G2, sirtuin 1, and superoxide dismutase 2; Supporting Table 3).32Foxo3 expression gradually returned to the time zero level on day 4 after PH (Fig. 6A); final adjustments of the regenerating liver tissue restored a normal liver/body weight index by 7 days in the mice (data not shown). No significant difference in Foxo3 expression was observed after sham surgeries in comparison with time zero (Fig. 6B). Gene expression is associated with an active chromatin structure [e.g., dimethylation of histone H3

at lysine 4 (H3K4me2) and acetylation of histone H3 at lysine 9 (H3K9), histone H3 at lysine 14 (H3K14), and several lysines of histone H4]. Using ChIP analysis of liver tissue collected 1 day after PH and sham surgeries, we tested whether histone modifications,

associated with active chromatin, decreased with a loss of p53 and TA-p73 binding in the Foxo3 p53RE region. We observed decreased levels of H3K4me2 and H3K14Ac (Fig. 7A) and a decrease in global H4 acetylation (Supporting Fig. 5) without a significant change in H3K9 acetylation (data not shown) at the Foxo3 p53RE in the regenerating liver on day Selleck Palbociclib 1 versus day 4 and the sham-operated mice. Although several methyltransferases and acetyltransferases modify H3K4, H3K14, and H4 residues, p53 and p73 are known to recruit CBP/p300 (lysine acetyltransferase Bcl-w 3A/3B [KAT3A/KAT3B]) to activate the transcription of target genes.33, 34 Using an antibody against p300, we observed a significant decrease in p300 binding to the Foxo3 p53RE region of chromatin in the quiescent liver of p53−/− mice (Fig. 7B). Binding of p300 to the Foxo3 p53RE decreased even further in the regenerating liver of WT mice on 1 day post-PH (Fig. 7C), and this suggests that both p53 and p73 contribute to the recruitment of p300 to activate expression of Foxo3 in the quiescent liver. Recruitment of p300 was restored on day 4 after PH along with p53

and p73. A genome-wide evaluation of p53-bound and p73-bound sequences by ChIP/chip analysis, using cultured cells, has shown that 72% of p53-bound sites are also bound by p73.35 In the current study, we uncovered 158 genes bound by TA-p73 in normal quiescent liver cells. Ten genes were known p53 targets, with the remainder not previously connected to p53/p73-mediated transcriptional regulation. In a recent review, Riley et al.36 identified stringent criteria for bona fide p53 target genes and generated a list of 129 genes containing at least one p53RE per gene. In our ChIP/chip experiments, we identified a similar number of TA-p73 target genes and confirmed binding of both p53 and TA-p73 to the p53REs of four target genes: Foxo3, Jak1, Pea15, and Tuba1a.