No requirement of reactive oxygen intermediates in Fas-mediated apoptosis

AbstractFas is a cell surface molecule that mediates apoptosis, but the intracellular mechanisms leading to apoptosis are not well understood. It is known that diethylmaleate (DEM)-induced cell death can be blocked by substances with antioxidant activity. Here we have studied whether antioxidants have any effect on Fas-mediated apoptosis and show that they are not able to block Fas-mediated apoptosis. Therefore, it seems that reactive oxygen intermediate (ROI)-dependent and -independent mechanisms which lead to apoptosis do exist. Fas-mediated apoptosis probably proceeds via a ROI-independent pathway

CPP32/Yama/apopain cleaves the catalytic component of DNA-dependent protein kinase in the holoenzyme

AbstractDNA-dependent protein kinase (DNA-PK) is composed of a 460-kDa catalytic component (p460) and a DNA-binding component Ku protein. Immunoblot analysis after treatment of Jurkat cells with anti-Fas antibody demonstrated the cleavage of p460 concomitantly with an increase in CPP32/Yama/apopain activity. Recombinant CPP32/Yama/apopain specifically cleaved p460 in the DNA-PK preparation that had been purified from Raji cells into 230- and 160-kDa polypeptides, the latter of which was detected in anti-Fas-treated Jurkat cells. The regulatory component Ku protein was not significantly affected by CPP32/Yama/apopain. DNA-PK activity was decreased with the disappearance of p460 in the incubation of DNA-PK with CPP32/Yama/apopain. These results suggest that the catalytic component of DNA-PK is one of the target proteins for CPP32/Yama/apopain in Fas-mediated apoptosis

Oncogenic fusion gene CD74-NRG1 confers cancer stem cell-like properties in lung cancer through a IGF2 autocrine/paracrine circuit

The CD74-Neuregulin1 (NRG1) fusion gene was recently identified as novel driver of invasive mucinous adenocarcinoma, a malignant form of lung cancer. However, the function of the CD74-NRG1 fusion gene in adenocarcinoma pathogenesis and the mechanisms by which it may impart protumorigenic characteristics to cancer stem cells (CSC) is still unclear. In this study, we found that the expression of the CD74-NRG1 fusion gene increased the population of lung cancer cells with CSC-like properties. CD74-NRG1 expression facilitated sphere formation not only of cancer cells, but also of nonmalignant lung epithelial cells. Using a limiting dilution assay in a xenograft model, we further show that the CD74-NRG1 fusion gene enhanced tumor initiation. Mechanistically, we found that CD74-NRG1 expression promoted the phosphorylation of ErbB2/3 and activated the PI3K/Akt/NF-κB signaling pathway. Furthermore, the expression of the secreted insulin-like growth factor 2 (IGF2) and phosphorylation of its receptor, IGF1R, were enhanced in an NF-κB-dependent manner in cells expressing CD74-NRG1. These findings suggest that CD74-NRG1-induced NF-κB activity promotes the IGF2 autocrine/paracrine circuit. Moreover, inhibition of ErbB2, PI3K, NF-κB, or IGF2 suppressed CD74-NRG1-induced tumor sphere formation. Therefore, our study provides a preclinical rationale for developing treatment approaches based on these identified pathways to suppress CSC properties that promote tumor progression and recurrence. © 2016 American Association for Cancer Research

Auxin-induced rapid degradation of inhibitor of caspase-activated DNase (ICAD) induces apoptotic DNA fragmentation, caspase activation, and cell death:a cell suicide module

Caspase-activated DNase (CAD) is a major apoptotic nuclease, responsible for DNA fragmentation and chromatin condensation during apoptosis. CAD is normally activated in apoptosis as a result of caspase cleavage of its inhibitory chaperone ICAD. Other aspects of CAD regulation are poorly understood. In particular, it has been unclear whether direct CAD activation in non-apoptotic living cells can trigger cell death. Taking advantage of the auxin-inducible degron (AID) system, we have developed a suicide system with which ICAD is rapidly degraded in living cells in response to the plant hormone auxin. Our studies demonstrate that rapid ICAD depletion is sufficient to activate CAD and induce cell death in DT40 and yeast cells. In the vertebrate cells, ectopic CAD activation triggered caspase activation and subsequent hallmarks of caspase-dependent apoptotic changes, including phosphatidylserine exposure and nuclear fragmentation. These observations not only suggest that CAD activation drives apoptosis through a positive feedback loop, but also identify a unique suicide system that can be used for controlling gene-modified organisms

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements