Multiple apoptotic pathways induced by p53-dependent acidification in benzo[a]pyrene-exposed hepatic F258 cells

Polycyclic aromatic hydrocarbons (PAH), such as benzo[a]pyrene (B[a]P), are ubiquitous genotoxic environmental pollutants. Their DNA-damaging effects lead to apoptosis induction, through similar pathways to those identified after exposure to other DNA-damaging stimuli with activation of p53-related genes and the involvement of the intrinsic apoptotic pathway. However, at a low concentration of B[a]P (50 nM), our previous results pointed to the involvement of intracellular pH (pHi) variations during B[a]P-induced apoptosis in a rat liver epithelial cell line (F258). In the present work, we identified the mitochondrial F0F1-ATPase activity reversal as possibly responsible for pHi decrease. This acidification not only promoted executive caspase activation, but also activated leucocyte elastase inhibitor/leucocyte-derived DNase II (LEI/L-DNase II) pathway. p53 appeared to regulate mitochondria homeostasis, by initiating F0F1-ATPase reversal and endonuclease G (Endo G) release. In conclusion, a low dose of B[a]P induced apoptosis by recruiting a large panel of executioners apparently depending on p53 phosphorylation and, for some of them, on acidification.     

The diversity of aging models

Most of the signalling pathways involved in aging regulation have been recently found well conserved at various levels throughout the evolution. Taking this into account, a diversity of model organisms, including worms, rodents, and lemurs as well, allows to address different questions: how to understand the interactions between genetic and environmental factors while challenging theories of aging, to preserve hearing integrity, to fight against senescence of neural stem cells, or to explore brain fitness from gene expression to cognitive and social behavior? Here are the main issues that can be considered, stressing the complementarities of the models. The differentiation of aging physiological aspects from those induced by age-related pathologies will also be specified. By emphasizing recent ability of technologies to promote new aging insights, we discuss towards a better understanding of mechanisms governing aging.     

Milk fermented by Propionibacterium freudenreichii induces apoptosis of HGT-1 human gastric cancer cells

Background

Gastric cancer is one of the most common cancers in the world. The “economically developed countries” life style, including diet, constitutes a risk factor favoring this cancer. Diet modulation may lower digestive cancer incidence. Among promising food components, dairy propionibacteria were shown to trigger apoptosis of human colon cancer cells, via the release of short-chain fatty acids acetate and propionate.

Methodology/Principal Findings

A fermented milk, exclusively fermented by P. freudenreichii, was recently designed. In this work, the pro-apoptotic potential of this new fermented milk was demonstrated on HGT-1 human gastric cancer cells. Fermented milk supernatant induced typical features of apoptosis including chromatin condensation, formation of apoptotic bodies, DNA laddering, cell cycle arrest and emergence of a subG1 population, phosphatidylserine exposure at the plasma membrane outer leaflet, reactive oxygen species accumulation, mitochondrial transmembrane potential disruption, caspase activation and cytochrome c release. Remarkably, this new fermented milk containing P. freudenreichii enhanced the cytotoxicity of camptothecin, a drug used in gastric cancer chemotherapy.

Conclusions/Significance

Such new probiotic fermented milk may thus be useful as part of a preventive diet designed to prevent gastric cancer and/or as a food supplement to potentiate cancer therapeutic treatments.     

A Rhodococcus qsdA-encoded enzyme defines a novel class of large-spectrum quorum-quenching lactonases

A gene involved in N-acyl homoserine lactone (N-AHSL) degradation was identified by screening a genomic library of Rhodococcus erythropolis strain W2. This gene, named qsdA (for quorum-sensing signal degradation), encodes an N-AHSL lactonase unrelated to the two previously characterized N-AHSL-degrading enzymes, i.e., the lactonase AiiA and the amidohydrolase AiiD. QsdA is related to phosphotriesterases and constitutes the reference of a novel class of N-AHSL degradation enzymes. It confers the ability to inactivate N-AHSLs with an acyl chain ranging from C(6) to C(14), with or without substitution at carbon 3. Screening of a collection of 15 Rhodococcus strains and strains closely related to this genus clearly highlighted the relationship between the ability to degrade N-AHSLs and the presence of the qsdA gene in Rhodococcus. Bacteria harboring the qsdA gene interfere very efficiently with quorum-sensing-regulated functions, demonstrating that qsdA is a valuable tool for developing quorum-quenching procedures.     

Block copolymer-oligonucleotide conjugates for genotyping on microarrays

Polymer-oligonucleotide conjugates were synthesized from the amphiphilic block copolymer poly(tert-butylacrylamide-b-(N-acryloylmorpholine-co-N-acryloxysuccinimide)) using an original solid-phase DNA synthesis strategy. This method provided conjugates highly functionalized with oligonucleotides throughout the polymer chain. After purification, block copolymer-oligonucleotide conjugates were spotted on a multidetection microarray system developed by Apibio using a standard nanodroplet piezo inkjet spotting technique to develop the oligosorbent assay (OLISA). Two genotyping models (HLA-DQB1 and platelet glycoproteins [GPs]), which are particularly difficult to study with standard systems, were evaluated. For both models, block copolymer-oligonucleotide conjugates used as capture probes amplified the responses of in vitro diagnostic assays. The detection limit reached by using conjugates was estimated at 15 pM for a 219-bp DNA target (HLA-DQB1 model). Moreover, single nucleotide polymorphism was detected in the platelet GPs genotyping model. The use of polymer conjugates led to a significant improvement in both sensitivity and specificity of standard hybridization assays even when applied to complex biological models.     

Ginkgo biloba extract EGb 761 protects against mitochondrial aging in the brain and in the liver.

According to the free radical theory of aging, oxygen-derived free radicals causes the age-associated impairment at the cellular and tissue levels. The mitochondrial theory of aging points to mitochondria, and specially mitochondrial DNA, as the major targets of free radical attack upon aging. Thus, oxidative damage to mtDNA accumulate with age in human and rodent tissues and also is inversely related to maximum life span of mammals. Mitochondrial deficits, such as a decrease in mitochondrial membrane potential, occur upon aging due to oxidative damage. The age-related mitochondrial oxidative stress may be prevented by late onset administration of certain antioxidants, such as Ginkgo biloba extract EGb 761. These antioxidants may also delay the physiological impairment associated with aging.     

18F-FET MicroPET and MicroMRI for Anti-VEGF and Anti-PlGF Response Assessment in an Orthotopic Murine Model of Human Glioblastoma

BackgroundConflicting data exist for anti-cancer effects of anti-placental growth factor (anti-PlGF) in combination with anti-VEGF. Still, this treatment combination has not been evaluated in intracranial glioblastoma (GBM) xenografts. In clinical studies, position emission tomography (PET) using the radiolabeled amino acid O-(2-¹⁸F-fluoroethyl)-L-tyrosine (¹⁸F-FET) and magnetic resonance imaging (MRI) add complementary but distinct information about glioma growth; however, the value of ¹⁸F-FET MicroPET combined with MicroMRI has not been investigated preclinically. Here we examined the use of ¹⁸F-FET MicroPET and MicroMRI for evaluation of anti-VEGF and anti-PlGF treatment response in GBM xenografts.MethodsMice with intracranial GBM were treated with anti-VEGF, anti-PlGF + anti-VEGF or saline. Bioluminescence imaging (BLI), ¹⁸F-FET MicroPET and T2-weighted (T2w)-MRI were used to follow tumour development. Primary end-point was survival, and tumours were subsequently analysed for Ki67 proliferation index and micro-vessel density (MVD). Further, PlGF and VEGFR-1 expression were examined in a subset of the xenograft tumours and in 13 GBM patient tumours.ResultsAnti-VEGF monotherapy increased survival and decreased ¹⁸F-FET uptake, BLI and MVD, while no additive effect of anti-PlGF was observed. ¹⁸F-FET SUV_max tumour-to-brain (T/B) ratio was significantly lower after one week (114±6%, n = 11 vs. 143±8%, n = 13; p = 0.02) and two weeks of treatment (116±12%, n = 8 vs. 190±24%, n = 5; p = 0.02) in the anti-VEGF group as compared with the control group. In contrast, T2w-MRI volume was unaffected by anti-VEGF. Gene expression of PlGF and VEGFR-1 in xenografts was significantly lower than in patient tumours.Conclusion¹⁸F-FET PET was feasible for anti-angiogenic response evaluation and superior to T2w-MRI; however, no additive anti-cancer effect of anti-PlGF and anti-VEGF was observed. Thus, this study supports use of ¹⁸F-FET PET for response evaluation in future studies.     

Molecular genetics of the transcription factor GLIS3 identifies its dual function in beta cells and neurons

The GLIS family zinc finger 3 isoform (GLIS3) is a risk gene for Type 1 and Type 2 diabetes, glaucoma and Alzheimer's disease endophenotype. We identified GLIS3 binding sites in insulin secreting cells (INS1) (FDR q < 0.05; enrichment range 1.40–9.11 fold) sharing the motif wrGTTCCCArTAGs, which were enriched in genes involved in neuronal function and autophagy and in risk genes for metabolic and neuro-behavioural diseases. We confirmed experimentally Glis3-mediated regulation of the expression of genes involved in autophagy and neuron function in INS1 and neuronal PC12 cells. Naturally-occurring coding polymorphisms in Glis3 in the Goto-Kakizaki rat model of type 2 diabetes were associated with increased insulin production in vitro and in vivo, suggestive alteration of autophagy in PC12 and INS1 and abnormal neurogenesis in hippocampus neurons. Our results support biological pleiotropy of GLIS3 in pathologies affecting β-cells and neurons and underline the existence of trans?nosology pathways in diabetes and its co-morbidities.     

Cell wall chitosaccharides are essential components and exposed patterns of the phytopathogenic oomycete Aphanomyces euteiches

Chitin is an essential component of fungal cell walls, where it forms a crystalline scaffold, and chitooligosaccharides derived from it are signaling molecules recognized by the hosts of pathogenic fungi. Oomycetes are cellulosic fungus-like microorganisms which most often lack chitin in their cell walls. Here we present the first study of the cell wall of the oomycete Aphanomyces euteiches, a major parasite of legume plants. Biochemical analyses demonstrated the presence of ca. 10% N-acetyl-D-glucosamine (GlcNAc) in the cell wall. Further characterization of the GlcNAc-containing material revealed that it corresponds to noncrystalline chitosaccharides associated with glucans, rather than to chitin per se. Two putative chitin synthase (CHS) genes were identified by data mining of an A. euteiches expressed sequence tag collection and Southern blot analysis, and full-length cDNA sequences of both genes were obtained. Phylogeny analysis indicated that oomycete CHS diversification occurred before the divergence of the major oomycete lineages. Remarkably, lectin labeling showed that the Aphanomyces euteiches chitosaccharides are exposed at the cell wall surface, and study of the effect of the CHS inhibitor nikkomycin Z demonstrated that they are involved in cell wall function. These data open new perspectives for the development of antioomycete drugs and further studies of the molecular mechanisms involved in the recognition of pathogenic oomycetes by the host plants.