The human homologue of Caenorhabditis elegans CED-6 specifically promotes phagocytosis of apoptotic cells

AbstractA key feature of the process of programmed cell death (apoptosis) is the efficiency with which the dying cells are recognized and engulfed by phagocytes [1]. Apoptotic cells are rapidly cleared either by neighbouring cells acting as semi-professional phagocytes or by experts of the macrophage line, so that an inflammatory response is avoided [2]. The Caenorhabditis elegans gene ced-6 is required for efficient engulfment of apoptotic cells [3] and is one of a group of genes that define two partially redundant parallel pathways for the engulfment process [4,5]. These pathways may be conserved across evolution, as two other engulfment genes have human homologues. A CED-5 homologue is part of a human CrkII–DOCK180–Rac signaling pathway proposed to mediate cytoskeletal reorganization [6–8] and a CED-7 homologue is similar to the ABC transporters [9,10]. Here, we report the cloning and characterization of human CED-6, a human homologue of C. elegans CED-6. The 34 kDa hCED-6 protein is expressed in most tissues, some human cancer cells, and in primary human macrophages. We developed an assay that quantitates the phagocytic activity of mammalian macrophages: the number of apoptotic cells that have been internalized is measured by the uptake of lacZ-positive apoptotic cells by adherent transgenic macrophages. The results of this assay demonstrate that overexpression of hCED-6 promotes phagocytosis only of apoptotic cells and suggest that hCED-6 is the mammalian orthologue of C. elegans CED-6 and is a part of a highly conserved pathway that specifically mediates the phagocytosis of apoptotic cells

Inside out: the role of nucleocytoplasmic transport in ALS and FTLD

Neurodegenerative diseases are characterized by the presence of protein inclusions with a different protein content depending on the type of disease. Amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) are no exceptions to this common theme. In most ALS and FTLD cases, the predominant pathological species are RNA-binding proteins. Interestingly, these proteins are both depleted from their normal nuclear localization and aggregated in the cytoplasm. This key pathological feature has suggested a potential dual mechanism with both nuclear loss of function and cytoplasmic gain of function being at play. Yet, why and how this pathological cascade is initiated in most patients, and especially sporadic cases, is currently unresolved. Recent breakthroughs in C9orf72 ALS/FTLD disease models point at a pivotal role for the nuclear transport system in toxicity. To address whether defects in nuclear transport are indeed implicated in the disease, we reviewed two decades of ALS/FTLD literature and combined this with bioinformatic analyses. We find that both RNA-binding proteins and nuclear transport factors are key players in ALS/FTLD pathology. Moreover, our analyses suggest that disturbances in nucleocytoplasmic transport play a crucial initiating role in the disease, by bridging both nuclear loss and cytoplasmic gain of functions. These findings highlight this process as a novel and promising therapeutic target for ALS and FTLD.status: publishe

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Development of a Cradle-to-Grave Approach for Acetylated Acidic Sophorolipid Biosurfactants

International audienceMicrobial production of biosurfactants represents one of the most interesting alternatives to classical petrol-based compounds due to their low toxicity, high biodegradability, and biological production processes from renewable bioresources. However, some of the main drawbacks generally encountered are the low productivities and the small number of chemical structures available, which limit widespread application of biosurfactants. Although chemical derivatization of (microbial) biosurfactants offers opportunities to broaden the panel of available molecules, direct microbial synthesis is still the preferred option and the use of engineered strains is becoming a valid alternative. In this multidisciplinary work we show the entire process of conception, upscaling of fermentation (150 L) and sustainable purification (filtration), application (foaming, solubilization, antibacterial), and life cycle analysis of acetylated acidic sophorolipids, directly produced by the Starmerella bombicola esterase knock out yeast strain, rather than purified using chromatography from the classical, but complex, mixture of acidic and lactonic sophorolipids

A clinical prediction rule for the diagnosis of coronary artery disease: validation, updating, and extension

Aims The aim was to validate, update, and extend the Diamond-Forrester model for estimating the probability of obstructive coronary artery disease (CAD) in a contemporary cohort. Methods and results Prospectively collected data from 14 hospitals on patients with chest pain without a history of CAD and referred for conventional coronary angiography (CCA) were used. Primary outcome was obstructive CAD, defined as ≥50% stenosis in one or more vessels on CCA. The validity of the Diamond-Forrester model was assessed using calibration plots, calibration-in-the-large, and recalibration in logistic regression. The model was subsequently updated and extended by revising the predictive value of age, sex, and type of chest pain. Diagnostic performance was assessed by calculating the area under the receiver operating characteristic curve (c-statistic) and reclassification was determined. We included 2260 patients, of whom 1319 had obstructive CAD on CCA. Validation demonstrated an overestimation of the CAD probability, especially in women. The updated and extended models demonstrated a c-statistic of 0.79 (95% CI 0.77-0.81) and 0.82 (95% CI 0.80-0.84), respectively. Sixteen per cent of men and 64% of women were correctly reclassified. The predicted probability of obstructive CAD ranged from 10% for 50-year-old females with non-specific chest pain to 91% for 80-year-old males with typical chest pain. Predictions varied across hospitals due to differences in disease prevalence. Conclusion Our results suggest that the Diamond-Forrester model overestimates the probability of CAD especially in women. We updated the predictive effects of age, sex, type of chest pain, and hospital setting which improved model performance and we extended it to include patients of 70 years and olde

Phase Separation of C9orf72 Dipeptide Repeats Perturbs Stress Granule Dynamics

Liquid-liquid phase separation (LLPS) of RNA-binding proteins plays an important role in the formation of multiple membrane-less organelles involved in RNA metabolism, including stress granules. Defects in stress granule homeostasis constitute a cornerstone of ALS/FTLD pathogenesis. Polar residues (tyrosine and glutamine) have been previously demonstrated to be critical for phase separation of ALS-linked stress granule proteins. We now identify an active role for arginine-rich domains in these phase separations. Moreover, arginine-rich dipeptide repeats (DPRs) derived from C9orf72 hexanucleotide repeat expansions similarly undergo LLPS and induce phase separation of a large set of proteins involved in RNA and stress granule metabolism. Expression of arginine-rich DPRs in cells induced spontaneous stress granule assembly that required both eIF2α phosphorylation and G3BP. Together with recent reports showing that DPRs affect nucleocytoplasmic transport, our results point to an important role for arginine-rich DPRs in the pathogenesis of C9orf72 ALS/FTLD

Magnetic resonance imaging of the third molars: developing a protocol suitable for age estimation

Purpose: To develop a clinically feasible MRI protocol – using standard commercial 3T MR hardware – to visualize all four third molars for age estimation, with particular attention to distinguishing the highest developmental stages. Materials and methods: In vivo scans of eight volunteers aged 17 – 24 years and ex vivo scans of porcine jaws were performed to make a stepwise selection of adequate sequences. A bilateral four-channel flexible surface head coil was used. The maximum acceptable acquisition time was set at seven minutes. Two observers evaluated the suitability of the images. Results: T2-weighted images were preferred to T1-weighted images. To clearly distinguish root apices in (almost) fully developed third molars a spatial resolution of 0.30 x 0.30 mm² was necessary. Within the limited acquisition time only a TSE T2 sequence generated images with sufficient resolution. Thin slice TSE T2 and TSE 3D T2 sequences could not generate the desired resolution. A UTE sequence was tried, but could not be completed in vivo by the used hardware. Conclusion: Three Tesla MRI of the third molars is a feasible technique for age estimation, in which a TSE T2 sequence can provide the desired spatial resolution within a clinically acceptable acquisition time

Inside out : the role of nucleocytoplasmic transport in ALS and FTLD

Neurodegenerative diseases are characterized by the presence of protein inclusions with a different protein content depending on the type of disease. Amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) are no exceptions to this common theme. In most ALS and FTLD cases, the predominant pathological species are RNA-binding proteins. Interestingly, these proteins are both depleted from their normal nuclear localization and aggregated in the cytoplasm. This key pathological feature has suggested a potential dual mechanism with both nuclear loss of function and cytoplasmic gain of function being at play. Yet, why and how this pathological cascade is initiated in most patients, and especially sporadic cases, is currently unresolved. Recent breakthroughs in C9orf72 ALS/FTLD disease models point at a pivotal role for the nuclear transport system in toxicity. To address whether defects in nuclear transport are indeed implicated in the disease, we reviewed two decades of ALS/FTLD literature and combined this with bioinformatic analyses. We find that both RNA-binding proteins and nuclear transport factors are key players in ALS/FTLD pathology. Moreover, our analyses suggest that disturbances in nucleocytoplasmic transport play a crucial initiating role in the disease, by bridging both nuclear loss and cytoplasmic gain of functions. These findings highlight this process as a novel and promising therapeutic target for ALS and FTLD