The analysis quantifies the enormity of the clinical and economic burdens of NAFLD, which will likely increase as the incidence of NAFLD continues to rise. (Hepatology 2016;64:1577-1586).
The p53 tumor suppressor interacts with its negative regulator Mdm2 via the former’s N-terminal region and core domain. Yet the extreme p53 C-terminal region contains lysine residues ubiquitinated by Mdm2 and can bear post-translational modifications that inhibit Mdm2–p53 association. We show that, the Mdm2–p53 interaction is decreased upon deletion, mutation or acetylation of the p53 C-terminus. Mdm2 decreases the association of full-length but not C-terminally deleted p53 with a DNA target sequence in vitro and in cells. Further, using multiple approaches we demonstrate that a peptide from p53 C-terminus directly binds Mdm2 N-terminus in vitro. We also show that p300-acetylated p53 binds inefficiently to Mdm2 in vitro, and Nutlin-3 treatment induces C-terminal modification(s) of p53 in cells, explaining the low efficiency of Nutlin-3 in dissociating p53-MDM2 in vitro.
It is well established that p53 contacts DNA in a sequencedependent manner in order to transactivate its myriad target genes. Yet little is known about how p53 interacts with its binding site/response element (RE) within such genes in vivo in the context of nucleosomal DNA. In this study we demonstrate that both distal (5′) and proximal (3′) p53 REs within the promoter of the p21 gene in unstressed HCT116 colon carcinoma cells are localized within a region of relatively high nucleosome occupancy. In the absence of cellular stress, p53 is prebound to both p21 REs within nucleosomal DNA in these cells. Treatment of cells with the DNA-damaging drug doxorubicin or the p53 stabilizing agent Nutlin-3, however, is accompanied by p53-dependent subsequent loss of nucleosomes associated with such p53 REs. We show that in vitro p53 can bind to mononucleosomal DNA containing the distal p21 RE, provided the binding site is not close to the diad center of the nucleosome. In line with this, our data indicate that the p53 distal RE within the p21 gene is located close to the end of the nucleosome. Thus, lowand high-resolution mapping of nucleosome boundaries around p53 REs within the p21 promoter have provided insight into the mechanism of p53 binding to its sites in cells and the consequent changes in nucleosome occupancy at such sites.DNA binding | DNA damage
We reported previously that when cells are arrested in S phase, a subset of p53 target genes fails to be strongly induced despite the presence of high levels of p53. When DNA replication is inhibited, reduced p21 mRNA accumulation is correlated with a marked reduction in transcription elongation. Here we show that ablation of the protein kinase Chk1 rescues the p21 transcription elongation defect when cells are blocked in S phase, as measured by increases in both p21 mRNA levels and the presence of the elongating form of RNA polymerase II (RNAPII) toward the 39 end of the p21 gene. Recruitment of specific elongation and 39 processing factors (DSIF, CstF-64, and CPSF-100) is also restored. While additional components of the RNAPII transcriptional machinery, such as TFIIB and CDK7, are recruited more extensively to the p21 locus after DNA damage than after replication stress, their recruitment is not enhanced by ablation of Chk1. Significantly, ablating Chk2, a kinase closely related in substrate specificity to Chk1, does not rescue p21 mRNA levels during S-phase arrest. Thus, Chk1 has a direct and selective role in the elongation block to p21 observed during S-phase arrest. These findings demonstrate for the first time a link between the replication checkpoint mediated by ATR/Chk1 and the transcription elongation/ 39 processing machinery.[Keywords: Chk1; Chk2; S-phase checkpoint; p53; transcription elongation] Supplemental material is available at http://www.genesdev.org.
Patients with chronic hepatitis C (CHC) exhibit reduced work productivity owing to their disease. Historically, most regimens indicated for CHC genotype 1 (GT1) patients were administered with pegylated interferon (Peg‐IFN) and/or ribavirin (RBV), which further compromised work productivity during treatment. The aim of this study was to model the impact of LDV/SOF (ledipasvir/sofosbuvir), the first Peg‐IFN‐ and RBV‐free regimen for CHC GT1 patients, on work productivity from an economic perspective, compared to receiving no treatment. The WPAI‐SHP (Work Productivity and Activity Index–Specific Health Problem) questionnaire was administered to patients across the ION clinical trials (N = 1,923 U.S. patients). Before initiation of treatment, patients with CHC GT1 in the ION trials exhibited absenteeism and presenteeism impairments of 2.57% and 7.58%, respectively. Patients with cirrhosis exhibited greater work productivity impairment than patients without cirrhosis. In total, 93.21% of U.S. patients in the ION trials achieved SVR; these patients exhibited absenteeism and presenteeism impairments of 2.62% (P = 0.76, when compared to baseline) and 3.53% (P < 0.0001), respectively. Monetizing these data to the entire U.S. population, our model projects an annual societal cost of $7.1 billion owing to productivity loss in untreated GT1 CHC patients. Our model projects that, when compared to no treatment, treating all CHC GT1 patients with a regimen with very high viral eradication rates (LDV/SOF) would translate to annual productivity loss savings of $2.7 billion over a 1‐year time horizon. Conclusions: Patients with untreated HCV impose a substantial societal burden owing to reduced work productivity. As a result of improvements in work productivity, treatment of CHC GT1 patients with LDV/SOF‐based regimens is likely to result in significant cost savings from a societal perspective, relative to no treatment. (Hepatology 2015;61:1471–1478)
CH-C negatively affects work productivity (WP), creating a large economic burden. The aim of this study was to model the impact of sustained virologic response (SVR) on WP in CHC genotype 1 (GT1) patients in five European countries (EU5). Work Productivity and Activity Index-Specific Health Problem questionnaire was administered to patients across the ION clinical trials (n = 629 European patients). The analysis modelled a population of GT1 CHC patients over one year, who had been either not treated or treated with LDV/SOF. Sensitivity analyses assessed the possibility that CHC patients' labour costs were lower than the general population's and presented results by fibrosis stage. Before initiation of treatment, EU patients with CHC GT1 exhibited absenteeism and presenteeism impairments of 3.54% and 9.12%, respectively. About 91.8% of EU patients in the ION trials achieved SVR and improved absenteeism and presenteeism impairments by 16.3% and 19.5%, respectively. Monetizing these data, treatment with LDV/SOF resulted in an annual productivity gain of €435 million and a weighted average per-employed patient (PEP) gain of €900 in the EU5. PEP gains from treatment are projected to be higher in cirrhotic than in noncirrhotic patients. If CHC patients are assumed to earn 20% less than the general population, gains of €348 million (€720 PEP) annually are projected. CHC results in a significant economic burden to European society. Due to improvements in WP, SVR with treatment could provide substantial economic gains, partly offsetting the direct costs related to its widespread use.
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