Listeria monocytogenes induces host DNA damage and delays the host cell cycle to promote infection

Listeria monocytogenes (Lm) is a human intracellular pathogen widely used to uncover the mechanisms evolved by pathogens to establish infection. However, its capacity to perturb the host cell cycle was never reported. We show that Lm infection affects the host cell cycle progression, increasing its overall duration but allowing consecutive rounds of division. A complete Lm infectious cycle induces a S-phase delay accompanied by a slower rate of DNA synthesis and increased levels of host DNA strand breaks. Additionally, DNA damage/replication checkpoint responses are triggered in an Lm dose-dependent manner through the phosphorylation of DNA-PK, H2A.X, and CDC25A and independently from ATM/ATR. While host DNA damage induced exogenously favors Lm dissemination, the override of checkpoint pathways limits infection. We propose that host DNA replication disturbed by Lm infection culminates in DNA strand breaks, triggering DNA damage/replication responses, and ensuring a cell cycle delay that favors Lm propagation.     

Insulin/IGF-I Signaling Pathways Enhances Tumor Cell Invasion through Bisecting GlcNAc N-glycans Modulation. An Interplay with E-Cadherin

Changes in glycosylation are considered a hallmark of cancer, and one of the key targets of glycosylation modifications is E-cadherin. We and others have previously demonstrated that E-cadherin has a role in the regulation of bisecting GlcNAc N-glycans expression, remaining to be determined the E-cadherin-dependent signaling pathway involved in this N-glycans expression regulation. In this study, we analysed the impact of E-cadherin expression in the activation profile of receptor tyrosine kinases such as insulin receptor (IR) and IGF-I receptor (IGF-IR). We demonstrated that exogenous E-cadherin expression inhibits IR, IGF-IR and ERK 1/2 phosphorylation. Stimulation with insulin and IGF-I in MDA-MD-435 cancer cells overexpressing E-cadherin induces a decrease of bisecting GlcNAc N-glycans that was accompanied with alterations on E-cadherin cellular localization. Concomitantly, IR/IGF-IR signaling activation induced a mesenchymal-like phenotype of cancer cells together with an increased tumor cell invasion capability. Altogether, these results demonstrate an interplay between E-cadherin and IR/IGF-IR signaling as major networking players in the regulation of bisecting N-glycans expression, with important effects in the modulation of epithelial characteristics and tumor cell invasion. Here we provide new insights into the role that Insulin/IGF-I signaling play during cancer progression through glycosylation modifications.     

Prediction of Complex Human Traits Using the Genomic Best Linear Unbiased Predictor

Despite important advances from Genome Wide Association Studies (GWAS), for most complex human traits and diseases, a sizable proportion of genetic variance remains unexplained and prediction accuracy (PA) is usually low. Evidence suggests that PA can be improved using Whole-Genome Regression (WGR) models where phenotypes are regressed on hundreds of thousands of variants simultaneously. The Genomic Best Linear Unbiased Prediction (G-BLUP, a ridge-regression type method) is a commonly used WGR method and has shown good predictive performance when applied to plant and animal breeding populations. However, breeding and human populations differ greatly in a number of factors that can affect the predictive performance of G-BLUP. Using theory, simulations, and real data analysis, we study the performance of G-BLUP when applied to data from related and unrelated human subjects. Under perfect linkage disequilibrium (LD) between markers and QTL, the prediction R-squared (R²) of G-BLUP reaches trait-heritability, asymptotically. However, under imperfect LD between markers and QTL, prediction R² based on G-BLUP has a much lower upper bound. We show that the minimum decrease in prediction accuracy caused by imperfect LD between markers and QTL is given by (1−b)², where b is the regression of marker-derived genomic relationships on those realized at causal loci. For pairs of related individuals, due to within-family disequilibrium, the patterns of realized genomic similarity are similar across the genome; therefore b is close to one inducing small decrease in R². However, with distantly related individuals b reaches very low values imposing a very low upper bound on prediction R². Our simulations suggest that for the analysis of data from unrelated individuals, the asymptotic upper bound on R² may be of the order of 20% of the trait heritability. We show how PA can be enhanced with use of variable selection or differential shrinkage of estimates of marker effects.     

Ultrasonication of insulin-loaded microgel particles produced by internal gelation: Impact on particle's size and insulin bioactivity

Alginate-dextran sulfate (ADS) microgel has been used to protect insulin from gastrointestinal attack and as a carrier to promote insulin permeation through intestinal epithelium. The throughput of ADS submicron particles generation by emulsification/internal gelation is limited by its wide size distribution.     

Severe abnormalities in the oral mucosa induced by suprabasal expression of epidermal keratin K10 in transgenic mice

Previous studies have demonstrated that keratin K10 plays an important role in mediating cell signaling processes, since the ectopic expression of this keratin induces cell cycle arrest in proliferating cells in vitro and in vivo. However, apart from its well known function of providing epithelial cells with resilience to mechanical trauma, little is known about its possible roles in nondividing cells. To investigate what these might be, transgenic mice were generated in which the expression of K10 was driven by bovine K6beta gene control elements (bK6(beta)hK10). The transgenic mice displayed severe abnormalities in the tongue and palate but not in other K6-expressing cells such as those of the esophagus, nails, and hair follicles. The lesions in the tongue and palate included the cytolysis of epithelial suprabasal cells associated with an acute inflammatory response and lymphocyte infiltration. The alterations in the oral mucosa caused the death of transgenic pups soon after birth, probably because suckling was impaired. These anomalies, together with others found in the teeth, are reminiscent of the lesions observed in some patients with pachyonychia congenita, an inherited epithelial fragility associated with mutations in keratins K6 and K16. Although no epithelial fragility was observed in the bK6(beta)hK10 oral epithelia of the experimental mice, necrotic processes were seen. Collectively, these data show that the carefully regulated tissue- and differentiation-specific patterns displayed by the keratin genes have dramatic consequences on the biological behavior of epithelial cells and that changes in the specific composition of the keratin intermediate filament cytoskeleton can affect their physiology, in particular those of the oral mucosa.     

FAS/FASL Expression Profile as a Prognostic Marker in Squamous Cell Carcinoma of the Oral Cavity

FAS/FASL altered expression may cause tumor protecting immunomodulation, with a direct impact on patient prognosis. FAS expression was studied in 60 squamous cell carcinomas of the oral cavity. FAS expression did not show a significant association with tumor histopathological characteristics, but was significantly associated with lymph node positivity. FAS expression was significantly associated with disease specific death and negative FAS expression was an independent risk factor, increasing risk 4 times when compared to positive expression. When FAS and FASL expression results were combined, we were able to define high, intermediate and low risk profiles. Disease-free and disease-specific survival were significantly correlated with FAS/FASL expression profiles. The high risk category was an independent marker for earlier disease relapse and disease-specific death, with approximately 4- and 6-fold increased risk, respectively, when compared to the low risk profile. Risk profiles based on FAS/FASL expression showed that high risk was significantly associated with increased disease relapse and death, as well as shorter disease-free or disease-specific survival. This categorization, added to patient clinical data, may facilitate the choice of therapy, minimizing treatment failure and increasing disease control.     

Genome-wide evaluation of histone methylation changes associated with leaf senescence in Arabidopsis

Leaf senescence is the orderly dismantling of older tissue that allows recycling of nutrients to developing portions of the plant and is accompanied by major changes in gene expression. Histone modifications correlate to levels of gene expression, and this study utilizes ChIP-seq to classify activating H3K4me3 and silencing H3K27me3 marks on a genome-wide scale for soil-grown mature and naturally senescent Arabidopsis leaves. ChIPnorm was used to normalize data sets and identify genomic regions with significant differences in the two histone methylation patterns, and the differences were correlated to changes in gene expression. Genes that showed an increase in the H3K4me3 mark in older leaves were senescence up-regulated, while genes that showed a decrease in the H3K4me3 mark in the older leaves were senescence down-regulated. For the H3K27me3 modification, genes that lost the H3K27me3 mark in older tissue were senescence up-regulated. Only a small number of genes gained the H3K27me3 mark, and these were senescence down-regulated. Approximately 50% of senescence up-regulated genes lacked the H3K4me3 mark in both mature and senescent leaf tissue. Two of these genes, SAG12 and At1g73220, display strong senescence up-regulation without the activating H3K4me3 histone modification. This study provides an initial epigenetic framework for the developmental transition into senescence.     

Effect of Cattle on Salmonella Carriage,Diversity and Antimicrobial Resistance in Free-Ranging Wild Boar (Sus scrofa) in Northeastern Spain

Salmonella is distributed worldwide and is a pathogen of economic and public health importance. As a multi-host pathogen with a long environmental persistence, it is a suitable model for the study of wildlife-livestock interactions. In this work, we aim to explore the spill-over of Salmonella between free-ranging wild boar and livestock in a protected natural area in NE Spain and the presence of antimicrobial resistance. Salmonella prevalence, serotypes and diversity were compared between wild boars, sympatric cattle and wild boars from cattle-free areas. The effect of age, sex, cattle presence and cattle herd size on Salmonella probability of infection in wild boars was explored by means of Generalized Linear Models and a model selection based on the Akaike’s Information Criterion. Prevalence was higher in wild boars co-habiting with cattle (35.67%, CI 95% 28.19–43.70) than in wild boar from cattle-free areas (17.54%, CI 95% 8.74–29.91). Probability of a wild boar being a Salmonella carrier increased with cattle herd size but decreased with the host age. Serotypes Meleagridis, Anatum and Othmarschen were isolated concurrently from cattle and sympatric wild boars. Apart from serotypes shared with cattle, wild boars appear to have their own serotypes, which are also found in wild boars from cattle-free areas (Enteritidis, Mikawasima, 4:b:- and 35:r:z35). Serotype richness (diversity) was higher in wild boars co-habiting with cattle, but evenness was not altered by the introduction of serotypes from cattle. The finding of a S. Mbandaka strain resistant to sulfamethoxazole, streptomycin and chloramphenicol and a S. Enteritidis strain resistant to ciprofloxacin and nalidixic acid in wild boars is cause for public health concern.