Phosphorylation of histone H2AX (cH2AX) is known to be the earliest indicator of DNA double-strand breaks. Recently, it has been shown that mouse embryonic stem cells (mESCs) have very high basal levels of cH2AX, even when they have not been exposed to genotoxic agents. As the specialized role of high basal cH2AX levels in pluripotent stem cells is still debated, we investigated whether H2AX phosphorylation is important in maintaining selfrenewal of these cells. Here, we report that not only mESCs but also mouse-induced pluripotent stem cells (miPSCs), have high basal levels of cH2AX. We show that basal cH2AX levels decrease upon ESC and iPSC differentiation and increase when the cells are treated with selfrenewal-enhancing small molecules. We observe that selfrenewal activity is highly compromised in H2AX2/2 cells and that it can be restored in these cells through reconstitution with a wild-type, but not a phospho-mutated, H2AX construct. Taken together, our findings suggest a novel function of H2AX that expands the knowledge of this histone variant beyond its role in DNA damage and into a new specialized biological function in mouse pluripotent stem cells.

Targeting of human cancer stem cells (CSCs) requires the identification of vulnerabilities unique to CSCs versus healthy resident stem cells (SCs). Unfortunately, dysregulated pathways that support transformed CSCs, such as Wnt/β-catenin signaling, are also critical regulators of healthy SCs. Using the ICG-001 and CWP family of small molecules, we reveal Sam68 as a previously unappreciated modulator of Wnt/β-catenin signaling within CSCs. Disruption of CBP-β-catenin interaction via ICG-001/CWP induces the formation of a Sam68-CBP complex in CSCs that alters Wnt signaling toward apoptosis and differentiation induction. Our study identifies Sam68 as a regulator of human CSC vulnerability.

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Generally, in order to detect shallow archaeological features, such as tombs, cavities, walls, etc., ground penetrating radar (GPR) data are acquired along parallel profiles. In some cases, the data collected using the GPR method are difficult to interpret owing to the presence of low signal‐to‐noise (S/N) ratio. These signals can be generated by several factors that significantly influence the radar profiles. To enhance the interpretation of radar sections, three‐dimensional data acquisition, radar signal processing and time‐slice representation are used. The archaeological investigated as a test site was the Sabine Necropolis (700–300 BC) at Colle del Forno (Montelibretti, Roma), believed to contain unexplored underground dromos chamber tombs. The measurements were carried out along parallel profiles in a test area, using Sir System 10 (GSSI) equipped with different antennas operating at 100, 300 and 500 MHz. The spatial interval used during the survey was 20 cm. To enhance the S/N ratio, a band‐pass filter and subtraction of an average trace on the field data has been applied; furthermore, the two‐dimensional migration technique on all profiles collected was used in order to move diffraction effects. A time‐slice representation technique was adopted to obtain a planimetric correlation between anomalous bodies at different depths. The results indicate that the three‐dimensional data acquisition, processing and the time slice representation can help determine the location, depth and shapes of buried features.

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Highly bright and photostable cyanine dye-doped silica nanoparticles, IRIS Dots, are developed, which can efficiently label human mesenchymal stem cells (hMSCs). The application procedure used to label hMSCs is fast (2 h), the concentration of IRIS Dots for efficient labeling is low (20 μg mL(-1) ), and the labeled cells can be visualized by flow cytometry, confocal microscopy, and transmission electron microscopy. Labeled hMSCs are unaffected in their viability and proliferation, as well as stemness surface marker expression and differentiation capability into osteocytes. Moreover, this is the first report that shows nonfunctionalized IRIS Dots can discriminate between live and early-stage apoptotic stem cells (both mesenchymal and embryonic) through a distinct external cell surface distribution. On the basis of biocompatibility, efficient labeling, and apoptotic discrimination potential, it is suggested that IRIS Dots can serve as a promising stem cell tracking agent.

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Ataxia telangiectasia (A-T) is a progressive neurodegenerative disease with onset in early childhood, caused by mutations in the ATM (ataxia-telangiectasia mutated) gene. Diagnosis relies on laboratory tests showing high levels of serum alphafetoprotein, cell sensitivity to ionizing radiation (IR) and absence or reduced levels of ATM protein.Many tests, however, are not sufficiently sensitive or specific for A-T, have long turnaround times, or require large blood samples. This prompted us to develop a new flow cytometry method for the diagnosis of A-T based on the measurement of histone H2AX phosphorylation. We established normal ranges of histone H2AX phosphorylation after 2 Gy IR by testing T-cell lines, lymphoblastoid cell lines (LCLs) and/or peripheral blood mononuclear cells (PBMCs) or both from 20 genetically proven A-T and 46 control donors. To further evaluate the specificity and sensitivity of the test, we analyzed cells from 19 patients suspected of having A-T, and from one Friedreich Ataxia, one Ataxia with Oculomotor Apraxia type 2, and one Nijmegen Breakage Syndrome patients. Phosphorylated histone H2AX mean fluorescence intensity of irradiated A-T cells was significantly lower than that of healthy donors. The intrastaining, intraassay, and interassay imprecisions were 13.22%. Sensitivity and specificity were virtually 100% when the test was performed on PBMCs.