Exome sequencing identifies rare damaging variants in ATP8B4 and ABCA1 as novel risk factors for Alzheimers Disease

The genetic component of Alzheimer’s disease (AD) has been mainly assessed using Genome Wide Association Studies (GWAS), which do not capture the risk contributed by rare variants. Here, we compared the gene-based burden of rare damaging variants in exome sequencing data from 32,558 individuals —16,036 AD cases and 16,522 controls— in a two-stage analysis. Next to known genes TREM2, SORL1 and ABCA7, we observed a significant association of rare, predicted damaging variants in ATP8B4 and ABCA1 with AD risk, and a suggestive signal in ADAM10. Next to these genes, the rare variant burden in RIN3, CLU, ZCWPW1 and ACE highlighted these genes as potential driver genes in AD-GWAS loci. Rare damaging variants in these genes, and in particular loss-of-function variants, have a large effect on AD-risk, and they are enriched in early onset AD cases. The newly identified AD-associated genes provide additional evidence for a major role for APP-processing, Aβ-aggregation, lipid metabolism and microglial function in AD

Exome sequencing identifies rare damaging variants in ATP8B4 and ABCA1 as risk factors for Alzheimer’s disease

Alzheimer’s disease (AD), the leading cause of dementia, has an estimated heritability of approximately 70%1. The genetic component of AD has been mainly assessed using genome-wide association studies, which do not capture the risk contributed by rare variants2. Here, we compared the gene-based burden of rare damaging variants in exome sequencing data from 32,558 individuals—16,036 AD cases and 16,522 controls. Next to variants in TREM2, SORL1 and ABCA7, we observed a significant association of rare, predicted damaging variants in ATP8B4 and ABCA1 with AD risk, and a suggestive signal in ADAM10. Additionally, the rare-variant burden in RIN3, CLU, ZCWPW1 and ACE highlighted these genes as potential drivers of respective AD-genome-wide association study loci. Variants associated with the strongest effect on AD risk, in particular loss-of-function variants, are enriched in early-onset AD cases. Our results provide additional evidence for a major role for amyloid-β precursor protein processing, amyloid-β aggregation, lipid metabolism and microglial function in AD

DERIVATION PORTOCAVE CHIRURGICALE POUR ASCITE REFRACTAIRE SUR CIRRHOSE (ANALYSE D'UNE SERIE DE 32 CAS)

RENNES1-BU Santé (352382103) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

4,5,5-Trimethyl-2,5-dihydrofuran-Based Electron-Withdrawing Groups for NIR-Emitting Push–Pull Dipolar Fluorophores

International audienceIn the context of molecular engineering of push−pull dipolar dyes, we introduce a structural modification of the well-known electron-accepting group 2-dicyanomethylidene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (TCF). Introduction of a (benzo-[d]thiazol-2-yl) moiety failed, and unexpected structures were obtained. On the other hand, phenylthio and phenylsulfonyl entities were successfully introduced at position 3 of the 2-(dicyanomethy-lidene)-2,5-dihydrofuran ring, giving access to new electron-acceptor groups and dipolar fluorophores displaying near-infrared emission in solution or in the solid state, brighter than their TCF analogues

Tuning the solid-state emission of small push-pull dipolar dyes to the far-red through variation of the electron-acceptor group

International audienceSeries of solid-state emitters based on the D-π-A dipolar structure and featuring various electron-donor and electron-acceptor groups were designed, and their spectroscopic properties studied. From weak emission in dilute solutions, intense emissions in aggregated state (AIE) and in the crystalline state were obtained. Analysis in light of crystal structures obtained by X-ray diffraction revealed specific crystal packing and presence of long chain of emitting aggregates. This simple molecular engineering around the D-π-A dipolar structure provides easy access to a wide range of effective solid-state emitters allowing modulation of emission wavelengths up to the near infrared (λem reaching 735 and 768 nm for compound 2f and 3f bearing the strongest electron-withdrawing group)

Photo-SRM: laser photo-dissociation improves detection selectivity of selected reaction monitoring mode

National audienceSelected Reaction Monitoring (SRM) carried out on triple quadrupole mass spectrometers coupled to liquid chromatography has been a reference method to develop quantitative analysis of small molecules in biological or environmental matrices for years and is currently emerging as a promising tool in clinical proteomics. However, sensitive assays in complex matrices are often hampered by the presence of co-eluted compounds that share redundant transitions with the target species. In the present work we document for the first time the potential interest of substituting classical gas-collision activation mode by laser photodissociation to track chromophore-derivatized target peptide absorbing at 532 nm diluted in a whole plasma trypsin hydrolysate. We anticipate that this technique coined photo-SRM, combined with chromophores endowed with reactivity towards generic chemical groups, might significantly improve the limit of quantification of classical SRM-based assays. The present presentation focused on the development of a new technique dedicated to quantification, called photo-SRM, where non-discriminating collision-activated dissociation mode has been replaced by a more specific photo-dissociation process governed by the absorbing properties of a targeted compound. The first example photo-SRM experiments has been developed in-house on a conventional triple quadrupole mass spectrometer. Proof of principle of SRM-based monitoring by laser-induced dissociation instead of classical collision activated mode was carried out with the chromophore-derivatized-Oxytocin as a model molecule diluted in whole plasma trypsin hydrolysate. This preliminary investigation clearly demonstrates that both the selectivity and detection level may markedly be improved during SRM monitoring by replacing the classical mode of activation by gas collision by a photon excitation providing a judicious overlap between the absorbing properties of the target molecule and the excitation wavelength of the laser beam. The lack of cross contamination within the transition channel between the target molecule and co-eluted endogenous interferences results here in a 50-fold improvement of the limit of quantification. The question rises now about how photo-SRM might be further optimized and extended to molecules that do not exhibit natural or specific light absorption. Novel aspect: First demonstration of Photo-SRM tool for analytical quantificatio

Red Emitting Neutral Fluorescent Glycoconjugates for Membrane Optical Imaging.

International audienceA family of neutral fluorescent probes was developed, mimicking the overall structure of natural glycolipids in order to optimize their membrane affinity. Nonreducing commercially available di- or trisaccharidic structures were connected to a push-pull chromophore based on dicyanoisophorone electron-accepting group, which proved to fluoresce in the red region with a very large Stokes shift. This straightforward synthetic strategy brought structural variations to a series of probes, which were studied for their optical, biophysical, and biological properties. The insertion properties of the different probes into membranes were evaluated on a model system using the Langmuir monolayer balance technique. Confocal fluorescence microscopy performed on muscle cells showed completely different localizations and loading efficiencies depending on the structure of the probes. When compared to the commercially available ANEPPS, a family of commonly used membrane imaging dyes, the most efficient probes showed a similar brightness, but a sharper pattern was observed. According to this study, compounds bearing one chromophore, a limited size of the carbohydrate moiety, and an overall rod-like shape gave the best results

Optical properties of a visible push-pull chromophore covalently bound to carbohydrates: solution and gas-phase spectroscopy combined to theoretical Investigations

International audienceThe use of visible absorbing and fluorescent tags for sensing and structural analysis of carbohydrates is a promising route in a variety of medical, diagnostic, and therapeutic contexts. Here we report an easy method for covalent attachment of nonfluorescent push-pull chromophores based on the 4-cyano-5-dicyanomethylene-2-oxo-3-pyrroline ring to carbohydrate moieties. The impact of sugar grafting on the optical properties of the push-pull chromophore in the gas phase and in solution was investigated by absorption and action spectroscopy and theoretical methods. The labeled sugars efficiently absorb photons in the visible range, as demonstrated by their intense photodissociation in a quadrupole ion trap. A strong blue shift (-70 nm) of the gas-phase photodissociation intensity maximum is observed upon sugar grafting, whereas no such effect is visible on the solution absorption spectra. Molecular dynamics simulations of labeled maltose in the gas phase describe strong interactions between the sulfonated chromophore and the carbohydrate, which lead to cyclic conformations. These are not observed in the simulations with explicit solvation. Time-dependent density functional theory (TD-DFT) calculations on model molecules permit us to attribute the observed shift to the formation of such cyclic conformations and to the displacement of the negative charge relative to the aromatic moiety of the chromophore

Photo-SRM: laser-induced dissociation improves detection selectivity of Selected Reaction Monitoring mode.

International audienceSelected Reaction Monitoring (SRM) carried out on triple-quadrupole mass spectrometers coupled to liquid chromatography has been a reference method to develop quantitative analysis of small molecules in biological or environmental matrices for years and is currently emerging as a promising tool in clinical proteomic. However, sensitive assays in complex matrices are often hampered by the presence of co-eluted compounds that share redundant transitions with the target species. On-the-fly better selection of the precursor ion by high-field asymmetric waveform ion mobility spectrometry (FAIMS) or increased quadrupole resolution is one way to escape from interferences. In the present work we document the potential interest of substituting classical gas-collision activation mode by laser-induced dissociation in the visible wavelength range to improve the specificity of the fragmentation step. Optimization of the laser beam pathway across the different quadrupoles to ensure high photo-dissociation yield in Q2 without detectable fragmentation in Q1 was assessed with sucrose tagged with a push-pull chromophore. Next, the proof of concept that photo-SRM ensures more specific detection than does conventional collision-induced dissociation (CID)-based SRM was carried out with oxytocin peptide. Oxytocin was derivatized by the thiol-reactive QSY® 7 C(5)-maleimide quencher on cysteine residues to shift its absorption property into the visible range. Photo-SRM chromatograms of tagged oxytocin spiked in whole human plasma digest showed better detection specificity and sensitivity than CID, that resulted in extended calibration curve linearity. We anticipate that photo-SRM might significantly improve the limit of quantification of classical SRM-based assays targeting cysteine-containing peptides