Coordinate 5′ and 3′ endonucleolytic trimming of terminally blocked blunt DNA double-strand break ends by Artemis nuclease and DNA-dependent protein kinase

Previous work showed that, in the presence of DNA-dependent protein kinase (DNA-PK), Artemis slowly trims 3′-phosphoglycolate-terminated blunt ends. To examine the trimming reaction in more detail, long internally labeled DNA substrates were treated with Artemis. In the absence of DNA-PK, Artemis catalyzed extensive 5′→3′ exonucleolytic resection of double-stranded DNA. This resection required a 5′-phosphate, but did not require ATP, and was accompanied by endonucleolytic cleavage of the resulting 3′ overhang. In the presence of DNA-PK, Artemis-mediated trimming was more limited, was ATP-dependent and did not require a 5′-phosphate. For a blunt end with either a 3′-phosphoglycolate or 3′-hydroxyl terminus, endonucleolytic trimming of 2–4 nucleotides from the 3′-terminal strand was accompanied by trimming of 6 nt from the 5′-terminal strand. The results suggest that autophosphorylated DNA-PK suppresses the exonuclease activity of Artemis toward blunt-ended DNA, and promotes slow and limited endonucleolytic trimming of the 5′-terminal strand, resulting in short 3′ overhangs that are trimmed endonucleolytically. Thus, Artemis and DNA-PK can convert terminally blocked DNA ends of diverse geometry and chemical structure to a form suitable for polymerase-mediated patching and ligation, with minimal loss of terminal sequence. Such processing could account for the very small deletions often found at DNA double-strand break repair sites

Projet MANOE, Maîtrise Allergène NutritiOn Enfant. Etude de la réactivité de patients allergiques à des faibles doses d'allergènes (blé, œuf, lait, arachide). Détection et quantification des allergènes présents à faibles doses dans des matrices alimentaires complexes

Ce numéro comprend les articles correspondant aux présentations du Colloque Allergies, intolérances et hypersensibilités alimentaires, qui s’est tenu à Paris le 17 juin 2016.In the absence of validated clinical thresholds and of subsequent regulatory thresholds, allergen risk management is not satisfactory for all stakeholders. For industry a real risk of cross contamination at a low level have to be labelled even though most of the allergic people might tolerate this low dose. On their side, patients faced multiple and inconsistent advised labels on food packaging. The MANOE project addressed this threshold issue to explore: 1/if it is possible to identify allergic children who tolerated low amount of allergen; 2/ how allergic people can be informed about their tolerance to low amount of allergen; 3/if commercial analytical methods are sensitive and quantitative to guaranty a risk of contamination below a threshold. An oral challenge with low doses of peanut, milk, wheat or egg was designed and enabled the identification of patients who tolerated low amount of allergen and it facilitated acceptance of a less restricted diet. Analytical methods detected all contaminations at 10 mg/kg but were not accurate for quantification of egg, milk and peanut notably in processed foods.En l’absence de seuils cliniques reconnus et de seuils réglementaires qui en découleraient, la gestion du risque allergène est insatisfaisante pour tous les acteurs concernés. Pour les industriels un risque avéré de contamination croisée à une dose très faible se doit d’être étiqueté même s’il apparait de plus en plus clairement que la plupart des patients allergiques pourraient consommer cette dose sans y réagir. De leur côté, les patients se trouvent confrontés à de multiples messages d’avertissement sans consistance. Le projet MANOE s’est placé dans un contexte de seuils, cliniques et analytiques, pour voir : 1/ S’il était possible d’identifier les enfants tolérants de petites doses d’allergène ; 2/ Comment cette information de tolérance de faible dose d’allergène pourraient être transmise au patient ; 3/ Si les méthodes analytiques commercialisées permettaient de détecter et de quantifier une contamination à une faible concentration. Appliqué à l’arachide, au blé, au lait et à l’œuf, un test oral de réintroduction a permis d’identifier les patients tolérants de petites doses et de faciliter l’acceptation d’un assouplissement de leur régime alimentaire. Les méthodes analytiques commercialisées se sont montrées capables de détecter des contaminations de 10 mg/kg mais pas de les quantifier dans le cas du lait, de l’arachide et de l’œuf

Sustained Effects of Nonallele-Specific Huntingtin Silencing

Objective: Huntington's disease (HD) is a fatal autosomal dominant neurodegenerative disorder caused by a polyglutamine expansion in the huntingtin (htt) protein. No cure is available to date to alleviate neurodegeneration. Recent studies have demonstrated that RNA interference represents a promising approach for the treatment of autosomal dominant disorders. But whether an allele-specific silencing of mutant htt or a nonallele-specific silencing should be considered has not been addressed

Polycaprolactone / bioactive glass hybrid scaffolds with controlled porosity

International audienceInorganic-organic hybrids appear as promising bone substitutes since they associate the bone mineral forming ability of bioactive glasses (BG) with the toughness of polymers. In such hybrids, the main challenge concerns the incorporation of calcium into the BG silicate network, which plays a major role in biomineralisation. Hybrids comprised of polycaprolactone (PCL, M n = 80,000 g/mol) and SiO 2-CaO BG were produced by a sol-gel process and built into porous scaffolds with controlled pore and interconnection sizes. PCL was chosen as the polymer because its slow degradation in vivo makes it a suitable candidate for bone filling. The calcium incorporation, apatite-forming ability, mechanical properties and degradation rate of the hybrid scaffolds were evaluated

Polycaprolactone / bioactive glass hybrid scaffolds with controlled porosity

International audienceInorganic-organic hybrids appear as promising bone substitutes since they associate the bone mineral forming ability of bioactive glasses (BG) with the toughness of polymers. In such hybrids, the main challenge concerns the incorporation of calcium into the BG silicate network, which plays a major role in biomineralisation. Hybrids comprised of polycaprolactone (PCL, M n = 80,000 g/mol) and SiO 2-CaO BG were produced by a sol-gel process and built into porous scaffolds with controlled pore and interconnection sizes. PCL was chosen as the polymer because its slow degradation in vivo makes it a suitable candidate for bone filling. The calcium incorporation, apatite-forming ability, mechanical properties and degradation rate of the hybrid scaffolds were evaluated

Polycaprolactone / bioactive glass hybrid scaffolds with controlled porosity

International audienceInorganic-organic hybrids appear as promising bone substitutes since they associate the bone mineral forming ability of bioactive glasses (BG) with the toughness of polymers. In such hybrids, the main challenge concerns the incorporation of calcium into the BG silicate network, which plays a major role in biomineralisation. Hybrids comprised of polycaprolactone (PCL, M n = 80,000 g/mol) and SiO 2-CaO BG were produced by a sol-gel process and built into porous scaffolds with controlled pore and interconnection sizes. PCL was chosen as the polymer because its slow degradation in vivo makes it a suitable candidate for bone filling. The calcium incorporation, apatite-forming ability, mechanical properties and degradation rate of the hybrid scaffolds were evaluated