Proper repair of oxidatively damaged DNA bases is essential to maintain genome stability. 8-Oxoguanine (7,8-dihydro-8-oxoguanine, 8-oxoG) is a dangerous DNA lesion because it can mispair with adenine (A) during replication resulting in guanine to thymine transversion mutations. MUTYH DNA glycosylase is responsible for recognizing and removing the adenine from 8-oxoG:adenine (8-oxoG:A) sites. Biallelic mutations in the MUTYH gene predispose individuals to MUTYH-associated polyposis (MAP), and the most commonly observed mutation in some MAP populations is Y165C. Tyr165 is a ‘wedge’ residue that intercalates into the DNA duplex in the lesion bound state. Here, we utilize single molecule fluorescence microscopy to visualize the real-time search behavior of Escherichia coli and Mus musculus MUTYH WT and wedge variant orthologs on DNA tightropes that contain 8-oxoG:A, 8-oxoG:cytosine, or apurinic product analog sites. We observe that MUTYH WT is able to efficiently find 8-oxoG:A damage and form highly stable bound complexes. In contrast, MUTYH Y150C shows decreased binding lifetimes on undamaged DNA and fails to form a stable lesion recognition complex at damage sites. These findings suggest that MUTYH does not rely upon the wedge residue for damage site recognition, but this residue stabilizes the lesion recognition complex.

Summary The canonical Wnt pathway regulates numerous fundamental processes throughout development and adult physiology, and is often disrupted in diseases [1, 2, 3, 4]. Signal in the pathway is transduced by β-catenin, which in complex with Tcf/Lef, regulates transcription. Despite the many processes that the Wnt pathway governs, β-catenin acts primarily on a single cis-element in the DNA, the Wnt-Responsive Element (WRE), at times potentiated by a nearby Helper site. In this study, working with Xenopus, mouse, and human systems, we identified a cis-element, distinct from WRE, that β-catenin and Tcf act on. The element is 11-bp long, hundreds of bases apart from WRE, and exhibits a suppressive effect. In Xenopus patterning, loss of the 11-bp negative regulatory elements (11-bp NREs) broadened dorsal expression of siamois. In mouse embryonic stem cells, genomic deletion of the 11-bp NREs in the promoter elevated Brachyury expression. This reveals a previously unappreciated mechanism within the Wnt pathway, where gene response is not only driven by WREs, but also tuned by 11-bp NREs. Using EMSA and Chip, we found evidence for the NREs binding to β-catenin and Tcf – suggesting a dual action by β-catenin as a signal and a feedforward sensor. Analyzing β-catenin Chip-Seq in human cells, we found the 11-bp NREs co-localizing with WRE in 45–71% of the peaks, suggesting a widespread role for the mechanism. This study presents an example of a more complex cis-regulation by a signaling pathway, where a signal is processed through two distinct cis-elements in a gene circuitry.

IntroductionThe volume of adverse events (AEs) collected, analysed, and reported has been increasing at a rapid rate for over the past 10 years, largely due to the growth of solicited programmes. The proportion of various forms of solicited case data has evolved over time, with the main relative volume increase coming from Patient Support Programmes. In this study, we sought to examine the impact of the pooling of AE report data from solicited sources with data from spontaneous sources to safety signal detection using disproportionality analysis methods.MethodsTwo conditions were explored in which disproportionality scores from hypothetical drugs were evaluated in a simulated safety database. The first condition held occurrence of events constant and varied solicited case volume, while the second condition varied both proportion of occurrence of events and solicited case volume.ResultsIn the first setting, where all AE terms have the same probability to occur with any drug, increasing volumes of solicited cases while keeping occurrence of events constant leads to reduced variability in disproportionality scores, consequently reducing or eliminating identified signals of disproportionate reporting. In the second setting, varying both case volume and reporting rates can mask true safety signals and falsely identify signals where there are none.ConclusionsThis analysis of simulated data suggests that pooling AE data from solicited sources with spontaneous case data may impact the results of disproportionality analyses, masking true safety signals and identifying false positives. Therefore, increased volumes of safety data do not necessarily correlate with improved safety signal detection.

Background: Over the past decade, the volume of adverse events (AEs) reported to marketing authorization holders and regulators has been rapidly increasing each year, which has led to significant challenges in patient safety assessment. Three data sources that have largely contributed to the expansion in adverse event reports are patient support programs (PSPs), market research programs (MRPs), and social media. In this study, we sought to further understand the contribution of these safety data sources to the characterization of a product’s safety profile. Methods: Three separate approaches were taken that, when combined, can be used to evaluate each data source. The first identified any core company data sheet changes or drug safety label changes. The second evaluated the similarity of information through proportions of AEs between each solicited data source and spontaneous sources. Lastly, the completeness of information reported was evaluated through vigiGrade and compared across each data source. Results: One drug safety label change was identified from a patient support program, which involved regular contact with health care providers. No label changes were identified from market research programs or social media. Patient support programs, market research programs, and social media report similar proportions for HLGT as spontaneous sources. Market research programs and social media display very low vigiGrade scores. When broken down by subtype, traditional PSPs display high vigiGrade scores, while patient assistance programs display lower vigiGrade scores that were program dependent. Conclusions: This study did not demonstrate that certain data sources such as market research programs, social media, and patient assistance programs meaningfully contributed to the further understanding of the characterization of a product’s safety profile.

No abstract