Characterization of POC16/WDR90 Proteins in Centriole Integrity

Les centrioles sont des organites essentiels aux processus de division cellulaire et de signalisation de nombreux organismes eucaryotes. Ils sont caractérisés par une organisation de neuf triplets de microtubules, polarisés longitudinalement en trois régions distinctes : proximale, centrale et distale. Précisément, la région centrale est définie par la présence d’une charpente interne hélicoïdale macromoléculaire, ancrée à la jonction interne des microtubules A et B du triplet, décrite comme « connexion en Y ». Sa composition moléculaire et sa fonction n’ont pas été décrites à ce jour. Nous avons identifié la protéine POC16 comme l’un des premiers composants de la partie centrale du centriole. Il a été suggéré que qu’elle compose la « connexion en Y ». J’ai entrepris une analyse fonctionnelle et structurelle de POC16 chez Chlamydomonas et Paramecium, ainsi que de son homologue humain WDR90. J’ai mis en lumière son importance ainsi que celle de la charpente interne dans le maintien de l’intégrité de la paroi de microtubules qui préservent l’architecture et les fonctions du centriole

Simple and fast HPLC method for simultaneous determination of retinol, tocopherols, coenzyme Q10 and carotenoids in complex samples

International audienceThe effects of fat-soluble vitamins (such as vitamins A and E) and lipid microconstituents (such as carotenoids) on human health are now well established. However, high-performance liquid chromatography (HPLC) methods able to detect these molecules in simultaneous runs are often difficult to set up. We report here a 35-min reversed-phase HPLC method using a single C30 column kept at 35 degrees C with a gradient system of methanol, methyl-tert-butyl ether and water at a flow-rate of 1 mL/min. This method resolves 11 carotenoids, retinol, alpha- and gamma-tocopherol from complex matrixes such as food samples, human plasma and human adipose tissue within 35 min. The method is also able to separate coenzyme Q(10). The intra-day and inter-day coefficients of variation are suitable for routine clinical and scientific applications for the determination of lipid micronutrients from various sample types

In vitro and ex vivo metabolism of diallyl disulfide, a characteristic sulfur compound of garlic, in rat.

International audienc

Métabolisme du disulfure de diallyle, un composé anticancérogène de l’ail

National audienc

CCDC15 localizes to the centriole inner scaffold and controls centriole length and integrity

Centrioles are microtubule-based organelles responsible for forming centrosomes and cilia, which serve as microtubule-organizing, signaling, and motility centers. Biogenesis and maintenance of centrioles with proper number, size, and architecture are vital for their functions during development and physiology. While centriole number control has been well-studied, less is understood about their maintenance as stable structures with conserved size and architecture during cell division and ciliary motility. Here, we identified CCDC15 as a centriole protein that colocalizes with and interacts with the inner scaffold, a crucial centriolar subcompartment for centriole size control and integrity. Using ultrastructure expansion microscopy, we found that CCDC15 depletion affects centriole length and integrity, leading to defective cilium formation, maintenance, and response to Hedgehog signaling. Moreover, loss-of-function experiments showed CCDC15’s role in recruiting both the inner scaffold protein POC1B and the distal SFI1/Centrin-2 complex to centrioles. Our findings reveal players and mechanisms of centriole architectural integrity and insights into diseases linked to centriolar defects.</p

Exosomes surf on filopodia to enter cells at endocytic hot spots and shuttle within endosomes to scan the ER

Exosomes are nanovesicles released by virtually all cells which act as intercellular messengers by transfer of protein, lipid and RNA cargo. Their quantitative efficiency, routes of cell uptake and subcellular fate within recipient cells remain elusive. We quantitatively characterize exosome cell uptake which saturates with dose and time and reaches near 100 % ‘transduction’ efficiency at picomolar concentrations. Highly reminiscent of pathogenic bacteria and viruses, exosomes are recruited as single vesicles to the cell body by surfing on filopodia, as well as filopodia grabbing and pulling motions to reach endocytic hot spots at the filopodial base. Following internalization, exosomes shuttle within endocytic vesicles to scan the endoplasmic reticulum before being sorted into the lysosome as their final intracellular destination. Our data quantify and explain the efficiency of exosome internalization by recipient cells, establish a new parallel between exosome and virus host cell interaction and suggest unanticipated routes of subcellular cargo delivery

Management of Severe Bleeding in Patients Treated with Direct Oral Anticoagulants

International audienceThe use of prothrombin complex concentrates and the role of plasma concentration of anticoagulants in the management of bleeding in patients treated with direct oral anticoagulants are still debated. Our aim was to describe management strategies and outcomes of severe bleeding events in patients treated with direct oral anticoagulants.METHODS:We performed a prospective cohort study of 732 patients treated with dabigatran, rivaroxaban, or apixaban hospitalized for severe bleeding, included prospectively in the registry from June 2013 to November 2015.RESULTS:Bleeding was gastrointestinal or intracranial in 37% (212 of 732) and 24% (141 of 732) of the cases, respectively. Creatinine clearance was lower than 60 ml/min in 61% (449 of 732) of the cases. The plasma concentration of direct oral anticoagulants was determined in 62% (452 of 732) of the cases and was lower than 50 ng/ml or higher than 400 ng/ml in 9.2% (41 of 452) and in 6.6% (30 of 452) of the cases, respectively. Activated or nonactivated prothrombin complex concentrates were administered in 38% of the cases (281 of 732). Mortality by day 30 was 14% (95% CI, 11 to 16).CONCLUSIONS:Management of severe bleeding in patients treated with direct oral anticoagulants appears to be complex. The use of prothrombin complex concentrates differs depending on bleeding sites and direct oral anticoagulant plasma concentrations. Mortality differs according to bleeding sites and was similar to previous estimates