UHRF1 is a genome caretaker that facilitates the DNA damage response to γ-irradiation

10.1186/2041-9414-1-7Genome Integrity1

BRAFΔβ3−αC^{Δβ3-αC} in-frame deletion mutants differ in their dimerization propensity, HSP90 dependence, and druggability

In-frame BRAF exon 12 deletions are increasingly identified in various tumor types. The resultant BRAF$^{Δβ3-αC}$ oncoproteins usually lack five amino acids in the β3-αC helix linker and sometimes contain de novo insertions. The dimerization status of BRAF$^{Δβ3-αC}$ oncoproteins, their precise pathomechanism, and their direct druggability by RAF inhibitors (RAFi) has been under debate. Here, we functionally characterize BRAF$^{ΔLNVTAP>F}$ and two novel mutants, BRAF$^{delinsFS}$ and BRAF$^{ΔLNVT>F}$, and compare them with other BRAF$^{Δβ3-αC}$ oncoproteins. We show that BRAF$^{Δβ3-αC}$ oncoproteins not only form stable homodimers and large multiprotein complexes but also require dimerization. Nevertheless, details matter as aromatic amino acids at the deletion junction of some BRAF$^{Δβ3-αC}$ oncoproteins, e.g., BRAF$^{ΔLNVTAP>F}$, increase their stability and dimerization propensity while conferring resistance to monomer-favoring RAFi such as dabrafenib or HSP 90/CDC37 inhibition. In contrast, dimer-favoring inhibitors such as naporafenib inhibit all BRAF$^{Δβ3-αC}$ mutants in cell lines and patient-derived organoids, suggesting that tumors driven by such oncoproteins are vulnerable to these compounds

Aryl Hydrocarbon Receptor Repressor and TiPARP (ARTD14) Use Similar, but also Distinct Mechanisms to Repress Aryl Hydrocarbon Receptor Signaling

The aryl hydrocarbon receptor (AHR) regulates the toxic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The AHR repressor (AHRR) is an AHR target gene and functions as a ligand-induced repressor of AHR; however, its mechanism of inhibition is controversial. Recently, we reported that TCDD-inducible poly (ADP-ribose) polymerase (TiPARP; ARTD14) also acts as a repressor of AHR, representing a new player in the mechanism of AHR action. Here we compared the ability of AHRR- and TiPARP-mediated inhibition of AHR activity. TCDD increased AHRR mRNA levels and recruitment of AHRR to cytochrome P450 1A1 (CYP1A1) in MCF7 cells. Knockdown of TiPARP, but not AHRR, increased TCDD-induced CYP1A1 mRNA and AHR protein levels. Similarly, immortalized TiPARP−/− mouse embryonic fibroblasts (MEFs) and AHRR−/− MEFs exhibited enhanced AHR transactivation. However, unlike TiPARP−/− MEFs, AHRR−/− MEFs did not exhibit increased AHR protein levels. Overexpression of TiPARP in AHRR−/− MEFs or AHRRΔ8, the active isoform of AHRR, in TiPARP−/− MEFs reduced TCDD-induced CYP1A1 mRNA levels, suggesting that they independently repress AHR. GFP-AHRRΔ8 and GFP-TiPARP expressed as small diffuse nuclear foci in MCF7 and HuH7 cells. GFP-AHRRΔ8_Δ1-49, which lacks its putative nuclear localization signal, localized to both the nucleus and the cytoplasm, while the GFP-AHRRΔ8_Δ1-100 mutant localized predominantly in large cytoplasmic foci. Neither GFP-AHRRΔ8_Δ1-49 nor GFP-AHRRΔ8_Δ1-100 repressed AHR. Taken together, AHRR and TiPARP repress AHR transactivation by similar, but also different mechanisms

Educating medical trainees on medication reconciliation: a systematic review

Abstract Background Effective medication reconciliation is critical in reducing the risk of preventable adverse drug events. Medical trainees are often responsible for medication reconciliation on admission, transfer and discharge of the most vulnerable patients; therefore, it is important that trainees are educated on this aspect of quality care. Methods We conducted a systematic review using MEDLINE and EMBASE databases to identify education initiatives targeted at improving trainee skill and knowledge in carrying out medication reconciliation. Studies published in English or French between July 1980 and July 2013, where the primary focus of the article was the role of medical trainees in conducting medication reconciliation, and where trainee-specific data was reported, were included. Included articles must have reported trainee-specific data. Given the anticipated heterogeneity and array of outcomes, we were unable to employ a specific tool in assessing the risk of bias across studies. Results Seven studies met pre-specified eligibility criteria, indicating the lack of published education initiatives targeted towards improving trainee knowledge and experience. Four described an education intervention targeted towards students completing internal medicine clerkship, while the remaining 3 were implemented among residents. Although no two interventions were the same, 5 out of 7 included an experiential component. Conclusions Varying success was achieved with medication reconciliation education interventions. While some noted improved competence and/or confidence amongst trainees, namely undergraduate medical students, others noted little effect resulting from the intervention

Countercurrent Distribution of Iron and Copper in Acetylacetone-Butyl Acetate System

The aryl hydrocarbon receptor (AHR) mediates the toxic effects of dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin; TCDD), which include thymic atrophy, steatohepatitis, and a lethal wasting syndrome in laboratory rodents. Although the mechanisms of dioxin toxicity remain unknown, AHR signaling in hepatocytes is necessary for dioxin-induced liver toxicity. We previously reported that loss of TCDD-inducible poly(ADP-ribose) polymerase (TIPARP/PARP7/ARTD14), an AHR target gene and mono-ADP-ribosyltransferase, increases the sensitivity of mice to dioxin-induced toxicities. To test the hypothesis that TIPARP is a negative regulator of AHR signaling in hepatocytes, we generated Tiparpfl/fl mice in which exon 3 of Tiparp is flanked by loxP sites, followed by Cre-lox technology to create hepatocyte-specific (Tiparpfl/flCreAlb) and whole-body (Tiparpfl/flCreCMV; TiparpEx3-/-) Tiparp null mice. Tiparpfl/flCreAlb and TiparpEx3-/- mice given a single injection of 10 g/kg dioxin did not survive beyond day 7 and 9, respectively, while all Tiparp+/+ mice survived the 30-day treatment. Dioxin-exposed Tiparpfl/flCreAlb and TiparpEx3-/- mice had increased steatohepatitis and hepatotoxicity as indicated by greater staining of neutral lipids and serum alanine aminotransferase activity than similarly treated wild-type mice. Tiparpfl/flCreAlb and TiparpEx3-/- mice exhibited augmented AHR signalling, denoted by increased dioxin-induced gene expression. Metabolomic studies revealed alterations in lipid and amino acid metabolism in liver extracts from Tiparpfl/flCreAlb mice compared with wild-type mice. Taken together, these data illustrate that TIPARP is an important negative regulator of AHR activity, and that its specific loss in hepatocytes is sufficient to increase sensitivity to dioxin-induced steatohepatitis and lethality

Performance Artists Talking in the Eighties

With a particular interest in the connection of childhood experiences to an artist’s production, Linda Montano interviewed over 100 performance artists from 1979 to 1989 on the themes of sex, food, money, fame, ritual and death. Grouped according to these thematic categories, each section of interviews is accompanied by a short essay. A general introduction by A. Festa discusses art and everyday life, the autobiographical voice and talking performances, vis-à-vis Montano’s work and the history and nature of performance art. K. Stiles’s afterword considers this era of performance art in relation to certain social conditions of the times, with examples of performance art’s influence on other art forms and on society. Includes subject index and brief biographical notes on artists and authors. 71 bibl. ref

UHRF1 is a genome caretaker that facilitates the DNA damage response to γ-irradiation

Abstract Background DNA double-strand breaks (DSBs) caused by ionizing radiation or by the stalling of DNA replication forks are among the most deleterious forms of DNA damage. The ability of cells to recognize and repair DSBs requires post-translational modifications to histones and other proteins that facilitate access to lesions in compacted chromatin, however our understanding of these processes remains incomplete. UHRF1 is an E3 ubiquitin ligase that has previously been linked to events that regulate chromatin remodeling and epigenetic maintenance. Previous studies have demonstrated that loss of UHRF1 increases the sensitivity of cells to DNA damage however the role of UHRF1 in this response is unclear. Results We demonstrate that UHRF1 plays a critical role for facilitating the response to DSB damage caused by γ-irradiation. UHRF1-depleted cells exhibit increased sensitivity to γ-irradiation, suggesting a compromised cellular response to DSBs. UHRF1-depleted cells show impaired cell cycle arrest and an impaired accumulation of histone H2AX phosphorylation (γH2AX) in response to γ-irradiation compared to control cells. We also demonstrate that UHRF1 is required for genome integrity, in that UHRF1-depleted cells displayed an increased frequency of chromosomal aberrations compared to control cells. Conclusions Our findings indicate a critical role for UHRF1 in maintenance of chromosome integrity and an optimal response to DSB damage

The Epstein-Barr Virus-Encoded BILF1 Protein Modulates Immune Recognition of Endogenously Processed Antigen by Targeting Major Histocompatibility Complex Class I Molecules Trafficking on both the Exocytic and Endocytic Pathways ▿ † ‡

Despite triggering strong immune responses, Epstein-Barr virus (EBV) has colonized more than 90% of the adult human population. Successful persistence of EBV depends on the establishment of a balance between host immune responses and viral immune evasion. Here we have extended our studies on the EBV-encoded BILF1 protein, which was recently identified as an immunoevasin that functions by enhancing degradation of major histocompatibility complex class I (MHC-I) antigens via lysosomes. We now demonstrate that disruption of the EKT signaling motif of BILF1 by a K122A mutation impairs the ability of BILF1 to enhance endocytosis of surface MHC-I molecules, while subsequent lysosomal degradation was impaired by deletion of the 21-residue C-terminal tail of BILF1. Furthermore, we identified another mechanism of BILF1 immunomodulation: it targets newly synthesized MHC-I/peptide complexes en route to the cell surface. Importantly, although the diversion of MHC-I on the exocytic pathway caused a relatively modest reduction in cell surface MHC-I, presentation of endogenously processed target peptides to immune CD8+ effector T cells was reduced by around 65%. The immune-modulating functions of BILF1 in the context of the whole virus were confirmed in cells lytically infected with a recombinant EBV in which BILF1 was deleted. This study therefore extends our initial observations on BILF1 to show that this immunoevasin can target MHC-I antigen presentation via both the exocytic and endocytic trafficking pathways. The results also emphasize the merits of including functional T cell recognition assays to gain a more complete picture of immunoevasin effects on the antigen presentation pathway