A5034714480- Alzheimer's disease research and treatments
- Lipid Membrane Structure and Behavior
- Receptor Mechanisms and Signaling
- Advanced Fluorescence Microscopy Techniques
- Cholesterol and Lipid Metabolism
- Ion channel regulation and function
- Cellular transport and secretion
- Nicotinic Acetylcholine Receptors Study
- Amyloidosis: Diagnosis, Treatment, Outcomes
- Monoclonal and Polyclonal Antibodies Research
- Cell Image Analysis Techniques
- Fungal and yeast genetics research
- Neuroscience and Neuropharmacology Research
- Lysosomal Storage Disorders Research
- Photoreceptor and optogenetics research
- Advanced Electron Microscopy Techniques and Applications
- Sphingolipid Metabolism and Signaling
- Calcium signaling and nucleotide metabolism
- Plant Molecular Biology Research
- 14-3-3 protein interactions
- Metabolomics and Mass Spectrometry Studies
- Optical Coherence Tomography Applications
- Nuclear Receptors and Signaling
- X-ray Diffraction in Crystallography
- Rabbits: Nutrition, Reproduction, Health
Columbia University Irving Medical Center
2016-2023
Columbia University
2023
Institut du Cerveau
2009-2022
Inserm
2009-2020
Sorbonne Université
2003-2015
Centre National de la Recherche Scientifique
2003-2015
Université Paris Cité
2014
Pitié-Salpêtrière Hospital
2010-2012
Allen Institute for Brain Science
2011
Communication, Information, Médias
2010
Abnormalities in neuronal cholesterol homeostasis have been suspected or observed several neurodegenerative disorders including Alzheimer's disease, Parkinson's disease and Huntington's disease. However, it has not demonstrated whether an increased abundance of neurons vivo contributes to neurodegeneration. To address this issue, we used RNA interference methodology inhibit the expression 24-hydroxylase, encoded by Cyp46a1 gene, hippocampus normal mice. Cholesterol 24-hydroxylase controls...
Amyloid peptide (Aβ) is generated by sequential cleavage of the amyloid precursor protein (APP) β-secretase (Bacel) and γ-secretase. Aβ production increases after plasma membrane cholesterol loading through unknown mechanisms. To determine how APP-Bacel proximity affects this phenomenon, we developed a fluorescence lifetime imaging microscopy-Förster resonance energy transfer (FLIM-FRET) technique for visualization these molecules either epifluorescence or at only using total internal...
It is suspected that excess of brain cholesterol plays a role in Alzheimer's disease (AD). Membrane-associated was shown to be increased the individuals with sporadic AD and correlate severity disease. We hypothesized an increase membrane could trigger early phenotypes.We thus acutely loaded plasma cultured neurons reach 30% observed brains. found changes gene expression profiles are reminiscent stages. also cellular phenotypes. Indeed we enlarged aggregated endosomes using confocal electron...
Abstract The late endosome/lysosome (LE/Lys) lipid bis(monoacylglycero)phosphate (BMP) plays major roles in cargo sorting and degradation, regulation of cholesterol intercellular communication has been linked to viral infection neurodegeneration. Although BMP was initially described over fifty years ago, the enzymes regulating its synthesis remain unknown. first step biosynthetic pathway is conversion phosphatidylglycerol (PG) into lysophosphatidylglycerol (LPG) by a phospholipase A2 (PLA2)...
Abstract Small GTPases play a critical role in membrane traffic. Among them, Arf6 mediates transport to and from the plasma membrane, as well phosphoinositide signalling cholesterol homeostasis. Here we delineate molecular basis for link between homeostasis using an inducible knockout (KO) model of mouse embryonic fibroblasts (MEFs). We find that accumulation free late endosomes/lysosomes KO MEFs results mistrafficking Niemann–Pick type C protein NPC2, cargo cation-independent...
The phosphoinositide phosphatase synaptojanin 1 (SYNJ1) is a key regulator of synaptic function. We first tested whether SYNJ1 contributes to phenotypic variations in familial Alzheimer's disease (FAD) and show that polymorphisms are associated with age onset both early- late-onset human FAD cohorts. then interrogated levels could directly affect memory. increased autopsy brains from adults Down syndrome (DS/AD) inversely correlated synaptophysin levels, direct readout integrity. further...
The novel, functionalized heteropolymolybdate [(O2CCH2PO3)2Mo5O15]6- (1) has been synthesized and characterized by IR 31P NMR spectroscopy elemental analysis. Single-crystal X-ray analysis was carried out on Rb4KNa[(O2CCH2PO3)2Mo5O15]·H2O, which crystallizes in the monoclinic system, space group P21/n, with a = 10.146(2) Å, b 13.704(3) c 20.577(4) β 94.88(3)°, Z 4. title polyanion consists of ring five MoO6 octahedra four edge junctions one corner junction. This nonplanar arrangement is...
Classical FRET (Förster Resonance Energy Transfer) using two fluorescent labels (one for the donor and another one acceptor) is not efficient studying homodimerization of a protein as only half homodimers formed can be identified by this technique. We thus resorted to homoFRET detected time-resolved Fluorescence Anisotropy IMaging (tr-FAIM). To specifically image plasma membrane living cells, an original combination tr-FAIM Total Internal Reflection Lifetime Imaging Microscope (TIRFLIM) was...
Venoms are a rich source of ligands for ion channels, but very little is known about their capacity to modulate G-protein coupled receptor (GPCR) activity. We developed strategy identify novel toxins targeting GPCRs.We studied the interactions mamba venom fractions with alpha(1)-adrenoceptors in binding experiments (3)H-prazosin. The active peptide (AdTx1) was sequenced by Edman degradation and mass spectrometry fragmentation. Its synthetic homologue pharmacologically characterized using...
The snake toxin MT7 is a potent and specific allosteric modulator of the human M1 muscarinic receptor (hM1). We previously characterized by mutagenesis experiments functional determinants MT7-hM1 interaction (Fruchart-Gaillard, C., Mourier, G., Marquer, Stura, E., Birdsall, N. J., Servent, D. (2008) Mol. Pharmacol. 74, 1554–1563) more recently collected evidence indicating that may bind to dimeric form hM1 (Marquer, Fruchart-Gaillard, Grandjean, O., Girard, le Maire, M., Brown, S., (2010)...
Elevations in neuronal cholesterol have been associated with several degenerative diseases. An enhanced excitability and synchronous firing surviving neurons are among the sequels of death these diseases also some epileptic syndromes. Here, we attempted to increase levels, using a short hairpin RNA suppress expression enzyme cytochrome P450 family 46, subfamily A, polypeptide 1 gene (CYP46A1). This protein hydroxylates so facilitates transmembrane extrusion. A CYP46A1construction coupled...
The most common form of neuronal ceroid lipofuscinosis (NCL) is juvenile CLN3 disease (JNCL), a currently incurable neurodegenerative disorder caused by mutations in the gene. Based on our previous work and premise that affects trafficking cation-independent mannose-6 phosphate receptor its ligand NPC2, we hypothesised dysfunction leads to aberrant accumulation cholesterol late endosomes/lysosomes (LE/Lys) JNCL patients' brains.An immunopurification strategy was used isolate intact LE/Lys...
Monoiodinated, Met35-oxidized muscarinic toxin 7 (MT7ox) was synthesized, and its affinity constants for free or <i>N</i>-methyl scopolamine (NMS)-occupied hM<sub>1</sub> receptor were measured directly by equilibrium kinetic binding experiments. Identical values obtained with the two types of assay methods, 14 pM 0.9 nM in NMS-liganded states, respectively, highlighting a strong negative cooperativity between this allosteric NMS. results indirect experiments [<sup>3</sup>H]NMS using ternary...
Muscarinic MT7 toxin is a highly selective and potent antagonist of the M<sub>1</sub> subtype muscarinic receptor acts by binding to an allosteric site. To identify molecular determinants which interacts with this in its free NMS-occupied states, effect on potency alanine substitution was evaluated equilibrium kinetic experiments as well functional assays. The determination crystallographic structure MT7-derivative (MT7-diiodoTyr51) allowed selection candidate residues that are accessible...
The idea that GPCRs (G-protein-coupled receptors) may exist as homo- or hetero-oligomers, although still controversial, is now widely accepted. Nevertheless, the functional roles of oligomerization are unclear and gaining greater insight into mechanisms underlying dynamics GPCR assembly and, in particular, assessing effect ligands on this process seems important. We chose to focus our present study MT7 (muscarinic toxin 7), a highly selective allosteric peptide ligand, state hM1 (human M1...
In the past fifteen years notion that cell membranes are not homogenous and rely on microdomains to exert their functions has become widely accepted. Lipid rafts membrane enriched in cholesterol sphingolipids. They play a role cellular physiological processes such as signalling, trafficking1,2 but also thought be key players several diseases including viral or bacterial infections neurodegenerative diseases3. Yet existence is still matter of controversy4,5. Indeed, lipid raft size been...
Abstract Excess brain cholesterol is strongly implicated in the pathogenesis of Alzheimer’s disease (AD). Here we evaluated how presence a cholesterol-binding site (CBS) transmembrane and juxtamembrane regions amyloid precursor protein (APP) regulates its processing. We generated nine point mutations APP gene, changing charge and/or hydrophobicity amino-acids which were previously shown as part CBS. Most triggered reduction amyloid-β peptides Aβ40 Aβ42 secretion from transiently transfected...
Circumventing the limit imposed by diffraction is a major issue in instrumental development to realize finer resolutions biological samples. With STED microscopy, we exploit molecular transitions of fluorescent marker image well below Rayleigh criterion. Also combination with STED, propose use an alternative technique for optically sectioning emitters close water-glass interface selectively filtering supercritical emission at pupil plane. We discuss such system and its other imaging techniques.