H3K4me3 demethylation by the histone demethylase KDM5C/JARID1C promotes DNA replication origin firing

DNA replication is a tightly regulated process that initiates from multiple replication origins and leads to the faithful transmission of the genetic material. For proper DNA replication, the chromatin surrounding origins needs to be remodeled. However, remarkably little is known on which epigenetic changes are required to allow the firing of replication origins. Here, we show that the histone demethylase KDM5C/JARID1C is required for proper DNA replication at early origins. JARID1C dictates the assembly of the pre-initiation complex, driving the binding to chromatin of the pre-initiation proteins CDC45 and PCNA, through the demethylation of the histone mark H3K4me3. Fork activation and histone H4 acetylation, additional early events involved in DNA replication, are not affected by JARID1C downregulation. All together, these data point to a prominent role for JARID1C in a specific phase of DNA replication in mammalian cells, through its demethylase activity on H3K4me3.     

Optimization of Drug Delivery by Drug-Eluting Stents

Drug-eluting stents (DES), which release anti-proliferative drugs into the arterial wall in a controlled manner, have drastically reduced the rate of in-stent restenosis and revolutionized the treatment of atherosclerosis. However, late stent thrombosis remains a safety concern in DES, mainly due to delayed healing of the endothelial wound inflicted during DES implantation. We present a framework to optimize DES design such that restenosis is inhibited without affecting the endothelial healing process. To this end, we have developed a computational model of fluid flow and drug transport in stented arteries and have used this model to establish a metric for quantifying DES performance. The model takes into account the multi-layered structure of the arterial wall and incorporates a reversible binding model to describe drug interaction with the cells of the arterial wall. The model is coupled to a novel optimization algorithm that allows identification of optimal DES designs. We show that optimizing the period of drug release from DES and the initial drug concentration within the coating has a drastic effect on DES performance. Paclitaxel-eluting stents perform optimally by releasing their drug either very rapidly (within a few hours) or very slowly (over periods of several months up to one year) at concentrations considerably lower than current DES. In contrast, sirolimus-eluting stents perform optimally only when drug release is slow. The results offer explanations for recent trends in the development of DES and demonstrate the potential for large improvements in DES design relative to the current state of commercial devices.     

EPIMIC: A Simple Homemade Computer Program for Real-Time EPIdemiological Surveillance and Alert Based on MICrobiological Data

Background and Aims

Infectious diseases (IDs) are major causes of morbidity and mortality and their surveillance is critical. In 2002, we implemented a simple and versatile homemade tool, named EPIMIC, for the real-time systematic automated surveillance of IDs at Marseille university hospitals, based on the data from our clinical microbiology laboratory, including clinical samples, tests and diagnoses.

Methods

This tool was specifically designed to detect abnormal events as IDs are rarely predicted and modeled. EPIMIC operates using Microsoft Excel software and requires no particular computer skills or resources. An abnormal event corresponds to an increase above, or a decrease below threshold values calculated based on the mean of historical data plus or minus 2 standard deviations, respectively.

Results

Between November 2002 and October 2013 (11 years), 293 items were surveyed weekly, including 38 clinical samples, 86 pathogens, 79 diagnosis tests, and 39 antibacterial resistance patterns. The mean duration of surveillance was 7.6 years (range, 1 month-10.9 years). A total of 108,427 Microsoft Excel file cells were filled with counts of clinical samples, and 110,017 cells were filled with counts of diagnoses. A total of 1,390,689 samples were analyzed. Among them, 172,180 were found to be positive for a pathogen. EPIMIC generated a mean number of 0.5 alert/week on abnormal events.

Conclusions

EPIMIC proved to be efficient for real-time automated laboratory-based surveillance and alerting at our university hospital clinical microbiology laboratory-scale. It is freely downloadable from the following URL: http://www.mediterranee-infection.com/article.php?larub=157&titre=bulletin-epidemiologique (last accessed: 20/11/2015).     

Inheritance and QTL Mapping of Leaf Nutrient Concentration in a Cotton Inter-Specific Derived RIL Population

Developing and deploying cotton cultivars with high nutrient uptake, use efficiency and tolerance to nutrient related soil stresses is desirable to assist sustainable soil management. Genetic variation, heritability, selection response and quantitative trait loci (QTLs) were investigated for five macronutrients (P, K, Ca, Mg, S) and five micronutrients (Fe, Mn, B, Zn, and Cu) in a recombinant inbred line (RIL) population from an inter-specific cross between Gossypium hirsutum cv. Guazuncho 2, and G. barbadense accession VH8-4602. Na and K/Na ratio were also studied as the imbalance between Na and other nutrients is detrimental to cotton growth and development. The concentrations of nutrients were measured for different plant parts of the two parents and for leaf samples of the whole population collected at early to peak flowering in field experiments over two years in a sodic Vertosol soil. Parental contrast was large for most nutrient concentrations in leaves when compared with other plant parts. Segregation for leaf nutrient concentration was observed within the population with transgression for P, K, K/Na ratio and all micronutrients. Genotypic difference was the major factor behind within-population variation for most nutrients, while narrow sense heritability was moderate (0.27 for Mn and Cu, and 0.43 for B). At least one significant QTL was identified for each nutrient except K and more than half of those QTLs were clustered on chromosomes 14, 18 and 22. Selection response was predicted to be low for P and all micronutrients except B, high for K, Na and B, and very high for K/Na ratio. Correlations were more common between macronutrients, Na and K/Na ratio where the nature and strength of the relations varied (r=-0.69 to 0.76). We conclude that there is sufficient genetic diversity between these two tetraploid cotton species that could be exploited to improve cotton nutrient status by introgressing species-unique favourable alleles.     

Multiple roles of the nuclear receptors for oxysterols liver X receptor to maintain male fertility

Oxysterol nuclear receptors liver X receptor (LXR)alpha and LXRbeta are known to regulate lipid homeostasis in cells exposed to high amounts of cholesterol and/or fatty acids. In order to elucidate the specific and redundant roles of the LXRs in the testis, we explored the reproductive phenotypes of mice deficient of LXRalpha, LXRbeta, and both, of which only the lxralpha;beta-/- mice are infertile by 5 months of age. We demonstrate that LXRalpha-deficient mice had lower levels of testicular testosterone that correlated with a higher apoptotic rate of the germ cells. LXRbeta-deficient mice showed increased lipid accumulation in the Sertoli cells and a lower proliferation rate of the germ cells. In lxralpha;beta-/- mice, fatty acid metabolism was affected through a decrease of srebp1c and increase in scd1 mRNA expression. The retinoid acid signaling pathway was also altered in lxralpha;beta-/- mice, with a higher accumulation of all-trans retinoid receptor alpha, all-trans retinoid receptor beta, and retinoic aldehyde dehydrogenase-2 mRNA. Combination of these alterations might explain the deleterious phenotype of infertility observed only in lxralpha;beta-/- mice, even though lipid homeostasis seemed to be first altered. Wild-type mice treated with a specific LXR agonist showed an increase of testosterone production involving both LXR isoforms. Altogether, these data identify new roles of each LXR, collaborating to maintain both integrity and functions of the testis.     

Enhanced anti-proliferative effects of combinatorial treatment of delta-tocopherol and resveratrol in human HMC-1 cells

The tocopherols (alpha, beta-, gamma-, and delta-tocopherol) and resveratrol are phytochemicals with alleged beneficial effects against atherosclerosis, vascular diseases and different cancers. They both can act as antioxidants, but they also modulate signal transduction and gene expression by non-antioxidant mechanisms. Here we wanted to determine whether the combined treatment of mast cells with the two compounds inhibits cell proliferation more efficiently when compared to individual treatments. Both compounds inhibit HMC-1 mastocytoma cell proliferation and reduce the activity of Protein Kinase B (PKB/Akt) by inhibiting its Ser473-phosphorylation. The combination of 50 microM delta-tocopherol and 50 microM resveratrol inhibits proliferation of HMC-1 cells more efficiently when compared to single treatments. In line with this, PKB Ser473-phosphorylation is inhibited best by delta-tocopherol and resveratrol combinatory treatment. Resveratrol acts more efficiently as an inhibitor of PKB phosphorylation than alpha-, beta-, gamma-tocopherols, whereas delta-tocopherol shows a stronger inhibition possibly as a result of its apoptotic secondary effects. Our data suggest that delta-tocopherol and resveratrol can act additively in reducing cell proliferation and PKB phosphorylation. The combination of phytochemicals with relatively broad specificity on enzymes involved in signal transduction and gene expression may increase their activity in disease prevention by modulating several different molecular targets.     

Novel chiral isoxazole derivatives: synthesis and pharmacological characterization at human beta-adrenergic receptor subtypes

Isoxazole derivative (+/-)-4 and the three pairs of stereoisomeric 3-bromo-isoxazolyl amino alcohols (S,R)-(-)-7a/(R,R)-(+)-7b, (S,R)-(-)-8a/(R,R)-(+)-8b, and (S,R)-(-)-9a/(R,R)-(+)-9b were synthesized and assayed for their affinity and efficacy at human beta(1)-, beta(2)-, and beta(3)-adrenergic receptors (beta-ARs) in membranes from Chinese hamster ovary (CHO) cells stably transfected with the respective receptor subtype. Whereas derivative (+/-)-4 did not bind at all three beta-ARs, stereoisomers (S,R)-7a-(S,R)-9a behaved as high-affinity ligands at beta(1)- and, particularly, at beta(2)-ARs (K(i) 2.82-66.7 nM). The K(i) values of isomers (R,R)-7b-(R,R)-9b at beta(1)- and beta(2)-subtypes were about 30-100 times higher than those of their (S,R)-7a-9a counterparts, indicating a sizable stereochemical effect. The affinity at beta(3)-ARs was negligible for all the investigated compounds. When submitted to a functional assay, the three stereoisomeric pairs showed a comparable pattern of efficacy at all three beta-AR subtypes. The highest value of efficacy (75-90%) was observed at beta(2)-ARs, whereas all compounds behaved as partial agonists (30-60%) at the beta(3)-subtype. The lowest degree of efficacy (15-35%) was found at beta(1)-ARs. The affinity/efficacy profile of the derivatives under study has been compared with that of the two model compounds, Broxaterol [(+/-)-1] and BRL 37344 [(+/-)-6].