The adenovirus E4orf4 protein targets PP2A to the ACF chromatin-remodeling factor and induces cell death through regulation of SNF2h-containing complexes

The adenovirus E4 open-reading-frame 4 (E4orf4) protein regulates the progression of viral infection and when expressed individually it induces non-classical apoptosis in transformed cells. Here we show that E4orf4 associates with the ATP-dependent chromatin-remodeling factor ACF that consists of a sucrose non fermenting-2h (SNF2h) ATPase and an Acf1 regulatory subunit. Furthermore, E4orf4 targets protein phosphatase 2A (PP2A) to this complex and to chromatin. Obstruction of SNF2h activity inhibits E4orf4-induced cell death, whereas knockdown of Acf1 results in enhanced E4orf4-induced toxicity in both mammalian and yeast cells, and Acf1 overexpression inhibits E4orf4′s ability to downregulate early adenovirus gene expression in the context of viral infection. Knockdown of the Acf1 homolog, WSTF, inhibits E4orf4-induced cell death. Based on these results we suggest that the E4orf4–PP2A complex inhibits ACF and facilitates enhanced chromatin-remodeling activities of other SNF2h-containing complexes, such as WSTF–SNF2h. The resulting switch in chromatin remodeling determines life versus death decisions and contributes to E4orf4 functions during adenovirus infection

The Cytosolic Tail of the Golgi Apyrase Ynd1 Mediates E4orf4-Induced Toxicity in Saccharomyces cerevisiae

The adenovirus E4 open reading frame 4 (E4orf4) protein contributes to regulation of the progression of virus infection. When expressed individually, E4orf4 was shown to induce non-classical transformed cell-specific apoptosis in mammalian cells. At least some of the mechanisms underlying E4orf4-induced toxicity are conserved from yeast to mammals, including the requirement for an interaction of E4orf4 with protein phosphatase 2A (PP2A). A genetic screen in yeast revealed that the Golgi apyrase Ynd1 associates with E4orf4 and contributes to E4orf4-induced toxicity, independently of Ynd1 apyrase activity. Ynd1 and PP2A were shown to contribute additively to E4orf4-induced toxicity in yeast, and to interact genetically and physically. A mammalian orthologue of Ynd1 was shown to bind E4orf4 in mammalian cells, confirming the evolutionary conservation of this interaction. Here, we use mutation analysis to identify the cytosolic tail of Ynd1 as the protein domain required for mediation of the E4orf4 toxic signal and for the interaction with E4orf4. We also show that E4orf4 associates with cellular membranes in yeast and is localized at their cytoplasmic face. However, E4orf4 is membrane-associated even in the absence of Ynd1, suggesting that additional membrane proteins may mediate E4orf4 localization. Based on our results and on a previous report describing a collection of Ynd1 protein partners, we propose that the Ynd1 cytoplasmic tail acts as a scaffold, interacting with a multi-protein complex, whose targeting by E4orf4 leads to cell death

Long Wave Infrared Type II Superlattice Focal Plane Array Detector

The XBn/XBp family of barrier detectors enables diffusion limited dark currents comparable with HgxCd1-xTe Rule-07 and high quantum efficiencies. SCD’s XBp type II superlattice (T2SL) detector contains InAs/GaSb and InAs/AlSb T2SLs, and was designed for the long wave infrared (LWIR) atmospheric window using k · p based modeling of the energy bands and photo-response. Wafers are grown by molecular beam epitaxy and are fabricated into focal plane array (FPA) detectors using standard FPA processes, including wet and dry etching, indium bump hybridisation, under-fill, and back-side polishing. The 640 × 512 pixel, 15 μm pitch, detector goes by the name of ‘Pelican-D LW’ and exhibits a quantum efficiency of ~ 50 per cent with background limited performance at an operating temperature of 77 K. It has a cut-off wave length of ~ 9.5 μm, with a pixel operability of above 99 per cent. The detector gives a very stable image with a residual non uniformity of below 0.04 per cent over its useful dynamic range. A new digital read-out integrated circuit has been designed so that the complete detector closely follows the configuration of SCD’s MWIR Pelican-D detector

Program analysis is harder than verification: A computability perspective

We study from a computability perspective static program analysis, namely detecting sound program assertions, and verification, namely sound checking of program assertions. We first design a general computability model for domains of program assertions and correspond- ing program analysers and verifiers. Next, we formalize and prove an instantiation of Rice\u2019s theorem for static program analysis and verifica- tion. Then, within this general model, we provide and show a precise statement of the popular belief that program analysis is a harder prob- lem than program verification: we prove that for finite domains of pro- gram assertions, program analysis and verification are equivalent prob- lems, while for infinite domains, program analysis is strictly harder than verification

Guided self-assembly of lateral InAs/GaAs quantum-dot molecules for single molecule spectroscopy

We report on the growth and characterization of lateral InAs/GaAs (001) quantum-dot molecules (QDMs) suitable for single QDM optical spectroscopy. The QDMs, forming by depositing InAs on GaAs surfaces with self-assembled nanoholes, are aligned along the [] direction. The relative number of isolated single quantum dots (QDs) is substantially reduced by performing the growth on GaAs surfaces containing stepped mounds. Surface morphology and X-ray measurements suggest that the strain produced by InGaAs-filled nanoholes superimposed to the strain relaxation at the step edges are responsible for the improved QDM properties. QDMs are Ga-richer compared to single QDs, consistent with strain- enhanced intermixing. The high optical quality of single QDMs is probed by micro-photoluminescence spectroscopy in samples with QDM densities lower than 108 cm−2

S100A7 (Psoriasin), highly expressed in Ductal Carcinoma In Situ (DCIS), is regulated by IFN-gamma in mammary epithelial cells

<p>Abstract</p> <p>Background</p> <p>The aim of the present work was to explore signal transduction pathways used in the regulation of S100A7 (psoriasin). Members of the S100 gene family participate in many important cellular functions. Psoriasin, S100A8 (calgranulin A) and S100A9 (calgranulin B) are expressed in ductal carcinoma <it>in situ </it>(DCIS), as well as in the hyperproliferative skin disease, psoriasis. In the latter condition, a disturbance in the STAT pathway has recently been reported. This pathway is implicated in the regulation of IFN-gamma, widely recognized as a key cytokine in psoriasis. IFN-gamma also exerts anti-tumor action in a number of tumor cell types, including breast cancer. We therefore examined the effect of IFN-gamma and STAT-signaling on the psoriasin expression.</p> <p>Methods</p> <p>We established a TAC2 mouse mammary epithelial cell line with tetracycline-inducible psoriasin expression (Tet-Off). Viability in cell culture was estimated using MTS assay. Protein and gene expression were evaluated by Western blotting and quantitative real-time PCR. Statistical analyses were assessed using a one-tailed, paired t-test.</p> <p>Results</p> <p>We report the downregulation of psoriasin by IFN-gamma in the MDA-MB-468 breast cancer cell line, as well as the downregulation of psoriasin induced by anoikis in cell lines derived from different epithelial tissues. In contrast, IFN-gamma had no suppressive effect on calgranulin A or calgranulin B. IFN-gamma is an important activator of the STAT1 pathway and we confirmed an active signaling pathway in the cell lines that responded to IFN-gamma treatment. In contrast, in the SUM190 breast carcinoma cell line, IFN-gamma did not suppress the expression of endogenous psoriasin. Moreover, a reduced phosphorylation of the STAT1 protein was observed. We showed that IFN-gamma treatment and the inhibition of the transcription factor NFkappaB had a synergistic effect on psoriasin levels. Finally, in TAC2 cells with tetracycline-induced psoriasin expression, we observed the increased viability of psoriasin-expressing cells after IFN-gamma treatment.</p> <p>Conclusion</p> <p>Our data support the possibility that psoriasin expression is transcriptionally suppressed by IFN-gamma and that this effect is likely to be mediated by the activation of the STAT1 signaling pathway. The increased viability of psoriasin-expressing cells after IFN-gamma exposure suggests that psoriasin expression leads to the development of an apoptosis-resistant phenotype.</p

Marked alveolar apoptosis/proliferation imbalance in end-stage emphysema

BACKGROUND: Apoptosis has recently been proposed to contribute to the pathogenesis of emphysema. METHODS: In order to establish if cell fate plays a role even in end-stage disease we studied 16 lungs (9 smoking-associated and 7 α1antitrypsin (AAT)-deficiency emphysema) from patients who had undergone lung transplantations. Six unused donor lungs served as controls. Apoptosis was evaluated by TUNEL analysis, single-stranded DNA laddering, electron microscopy and cell proliferation by an immunohistochemical method (MIB1). The role of the transforming growth factor (TGF)-β1 pathway was also investigated and correlated with epithelial cell turnover and with the severity of inflammatory cell infiltrate. RESULTS: The apoptotic index (AI) was significantly higher in emphysematous lungs compared to the control group (p ≤ 0.01), particularly if only lungs with AAT-deficiency emphysema were considered (p ≤ 0.01 vs p = 0.09). The proliferation index was similar in patients and controls (1.9 ± 2.2 vs 1.7 ± 1.1). An increased number of T lymphocytes was observed in AAT-deficiency lungs than smoking-related cases (p ≤ 0.05). TGF-β1 expression in the alveolar wall was higher in patients with smoking-associated emphysema than in cases with AAT-deficiency emphysema (p ≤ 0.05). A positive correlation between TGF-βRII and AI was observed only in the control group (p ≤ 0.005, r(2 )= 0.8). A negative correlation was found between the TGF-β pathway (particularly TGF-βRII) and T lymphocytes infiltrate in smoking-related cases (p ≤ 0.05, r(2 )= 0.99) CONCLUSION: Our findings suggest that apoptosis of alveolar epithelial cells plays an important role even in end-stage emphysema particularly in AAT-deficiency disease. The TGFβ-1 pathway does not seem to directly influence epithelial turnover in end-stage disease. Inflammatory cytokine different from TGF-β1 may differently orchestrate cell fate in AAT and smoking-related emphysema types

Differential Cytokine Gene Expression According to Outcome in a Hamster Model of Leptospirosis

Leptospirosis is a widespread bacterial infection that is transmitted by soil or water contaminated by the urine of infected animals, or directly from these animals. It has highly diverse clinical presentations, making its differential diagnosis difficult. Though most cases are minor and self-resolving, there are also severe forms that include a sepsis pattern and multiple organ failure, and have possible fatal outcomes. Predictors of disease evolution and outcome are scarce, yet they would be very valuable to clinicians as well as to better decipher disease pathogenesis. In this study, we used a hamster model of leptospirosis to evaluate if immune genes were differentially expressed between individuals and if their expression levels could help forecast the outcome of the disease. We found that hamsters that later died from leptospirosis had significantly higher expression levels of both pro- and anti-inflammatory mediators compared to survivors. These results suggest that expression levels of these immune effectors might be helpful predictors of outcome in leptospirosis and that septic shock contributes to fatal leptospirosis

Mycosis fungoides: is it a Borrelia burgdorferi-associated disease?

Mycosis fungoides (MF) is the most frequently found cutaneous T-cell lymphoma with an unknown aetiology. Several aetiopathogenetic mechanisms have been postulated, including persistent viral or bacterial infections. We looked for evidence of Borrelia burgdorferi (Bb), the aetiologic agent of Lyme disease (LD), in a case study of MF patients from Northeastern Italy, an area with endemic LD. Polymerase chain reaction for the flagellin gene of Bb was used to study formalin-fixed paraffin-embedded lesional skin biopsies from 83 patients with MF and 83 sex- and age-matched healthy controls with homolocalised cutaneous nevi. Borrelia burgdorferi-specific sequence was detected in 15 out of 83 skin samples of patients with MF (18.1%), but in none out of 83 matched healthy controls (P<0.0001). The Bb positivity rates detected in this study support a possible role for Bb in the aetiopathogenesis of MF in a population endemic for LD